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Home My WebLink About3.2 Suplemental448 9'1:8-0;-34,00: ww EIH�n�aor Santa Clara County Onsite Systems Manual This onsite Systems Manual (also "Onsite Manual" or "Man and technical details for implementation of the provision Wastewater Systems Ordinance, codified in Sections 1311,6 County Code. Section B11-73 provides further that: ),provides the policy, procedural %'he Santa Clara County Onsite rough B11-95 of the Santa Clara The Onsite:Systems Manual shall be develop d and maintained by the Department of Environmental Health, and shall1provide a�e sonable process for�seeking input from the affected public and OWTS practitioners` n. connection with its develo 'ment and when changes are made. The Onsite Systems M6nualand any amendments shall be subject to approval by the director and by the San Francisc&Bay,and Centra[Coast Regional Water Quality Control Boards in accordance with applitabl&Stte requirements and policies for onsite wastewater treatment. the former'`Bulletin A and,''incorporates new and updated information This Manual replaces regarding design det ils a d guidel l es related t 6 both conventional and alternative .systems, operation and monitonng.;requirements.and related,procedural matters. It is expected that the Onsite Manual will be�re`vie ed and updated from time -to -time, typically ,,> annually t keep pace Milli neew issues, policies; procedures and technologies affecting the use and manage .+ent of onsite'systems The Onsite MahUdVis divided mtoA ive main sections as follows: k Section 1. Policies anc!Admmistrative Procedures Section 2: Site EvaluaMon Methods and Investigation Requirements Section 3: General and Conventional OWTS Requirements Section 4: Guidelines:for Alternative Systems Section 5: Operation, Monitoring,.and Maintenance Onsite Systems Manual - Introduction Page 1 SANTA CLARA COUNTY ONSITE SYSTEMS MANUAL f . PART 1 `f P 0 L I Ct-,ES AND=DMINISTRATIVE +F Al", `vD 11 RES C� � FTQ Onsite Manual - Part 1 . ' Page 1 PART 1 POLICIES AND ADMINISTRATIVE PROCEDURES A. OVERVIEW . Part 1 of the Onsite Systems Manual covers DEH policies d clarification of various Ordinance provisions along with ad General requirements,and applicability for subdi fi lots, remodeling projects, and system repairs; for explanation and/or ,fe procedures, such as: construction on existing Construction permit process, including yapplication, fees, site," review process, installation and inspection, and final approval; Operating permit requirements and procedbrr ssfoi systems; • Application forms and fees; andti" •Policy and procedure foraamendments to n=site information, design anual. dispersal B. INSTALLATION PERNfiT REQU1:REMENTS A A permit %st �bde otainefrom,the Departure t vironmental Health (DEH) to construct, reconstruct, or repair an individual no site wast ester treatment and dispersal system. Permits will only be sisued in those reas of the, o' unty where a sanitary sewer is not available within 300 feet. of the�p,operty line (or ithin 100 feet of the building in some cities).: OWTS cannot be used if soil conditions, topography, high groundwater or other factors indicate this method of X sewage disposal is unsu t� able , I Y" � '. To obtain a permit, five (5)";sets of the site plan showing the proposed OWTS; and any required supporting documents, must be submitted to DEH for review and approval. z, Onsite Manual - Part1 Page 2 C. FEES Fees, as prescribed by Resolution of the Board of Supervisors of the County of Santa Clara, are payable separately to the Department of Environmental Health for services described, throughout this Manual. D. DEVELOPMENT REQUIREMENTS Land use and building permit applications are evaluated for=a:deO'uate sewage disposal and domestic water supply. Other conditions such as hazardous n aterials storage or use, illegal dumping or illegal uses on the property may also be evaluated during field inspections. Evaluation/testing of any existing septic systems may also be required to determine condition .. and adequacy: 1. Site Approval - Individual Parcels, Subdivisions and Use Permits To determine feasibility and size of asepticsystem, a�ite assessment, soil profile, and percolation test are, required for sites for which septic syst s are proposed. An approved potable. water supply is req'ui d�as a o_ndition `6f4 roval for building sites,: pP g subdivisions, and most use permits ProA. f adequa a potable�domestic water for subdivisions may be required prior to _deerni gthe applrclon complete iwater availability is unknown or poor. Otherwise, pro" 0 of an adequate domestic w,afer.suppl�r=is required prior to -map recordation. Individua4welis or water systemsiiith up to 14 connections are regulated by DEH. The Californ a Department of Publc Healt�i, Drinking Water Division, regulates all other water systems. 2. Bui4h g Additions and-Acces pry Structures a. Min r' uildin additio u to 500 square feet and Accessory Structures barns g �p q ) N , detached garages, swimmng pools, cabanas, etc) Due to thevanabi ity, ing6lved, these projects are evaluated on a case-by-case basis. The construction of an- rtional septic tank/drainfield may be required if the existing system is undersized, shows evidence of failure, consists of;a Cesspool or other substandard septic system, or if there is intensification of use to the septic system (typically the addition of bedrooms). b. Major Building Additions (over 500 square feet) These. projects require that the existing septic system meet current standards as defined by the Santa Clara County Sewage Disposal Ordinance. Current standards require the Onsite Manual - Part 1 Page 3 minimum of a 1,500 gallon septic tank and a dual drainfield (primary and secondary drainfields) sized and sited to meet current code. Building additions/accessory structures will not be approved in situations where it would result in a reduction in size of the drainfield(s) or any required reserve drainfield area. c. Secondary Dwellings Each secondary dwelling shall be served by an This may be a separate OWTS serving only the may be connected to the main house system, capacity. Attached secondary dwellings must have dire secondary dwelling. Breezeways, porches; eti attached secondary dwellings, the septic tanN footage of the house (plus secondary dwellin the number of bedrooms for both he,main h E. ALTERNA To provide awb,roader ran repair/replacement-4 tua with certain general pr`o\ 1. G a ,,alternative s and'specif s= conforms to current code. ing, or the second dwelling e is treatment and dispersal access from the`'main house to the do not constitutedirect access. For vill Wsized based oh,the total square an{d_the. drainfield will beysized. based on ase: nd secondary dwelling. ent anddispersal options for new construction and t conventional OWTS may be used in accordance requirements as follows: a. Alternative systems may he permitted by the Director of Environmental Health for the repair or upgrading of `any existing OWTS and for new: construction on any legally - created parcel where -(a) it is determined that sewage cannot be disposed of in a sanitary manner byaa conventional OWTS; or, (b) the Director determines that an alternative system would provide equal or greater protection to public health anal the environmentthan a conventional OWTS. b.: Alternative systems are not to be used as the basis approval of creation of new lots (subdivisions). c. Types of alternative systems permitted are limited to those for which .siting and design standards have been adopted and incorporated in the Ordinance and this Manual. Onsite Manual - Part 1 Page 4 d. All alternative systems must be..installed by a contractor duly licensed by :the Contractors State License Board of the State of California to install OWTS. 2. Specific Requirements a. Design and _Installation Permit. Alternative OWTS . require design by a licensed professional and completion of site evaluation and installation permitting as required for conventional OWTS. Additional engineering and design requirements applicable to different types of alternative OWTS are contained in Parti of this Manual. M b. Operating Permits. A.County-issued operating permit is required for all alternative systems. Operating permits are intendedto serveasthe basis for verifying the adequacy of alternative system performance and ens -ring on-going maintenance, including_ requirements for system inspection monitoring and reporting of results.to the DEH, along with the requirement forl6p rmit renewal, typically: t DEPARTMENT OF ENVIRONMENTAL HEALTH CONSUMER PROTECTION DIVISION 3 1555 Berger Dr. Ste 300,.• San Jose CA 95112 :Coiiray,cP5atiwc a Telephone: 408 918-3400 • Fax 408 258-5891 ❑ Repair Failing Sys www.ehinfo.o�o ( Building: ❑ Single Family Dwelling Land Use Service. Application Form PLEASE NOTE: Submit. an initial site plan (scale 1 "=20) showing existing and proposed improvements. Scope: ❑ Vacant Parcel F1 Developed Parcel ❑ % 20Slope : El > 20% Slope j ❑ New Septic Sys ❑ Upgrade Existing Septic ❑ Repair Failing Sys ❑ Abandon Tank ( Building: ❑ Single Family Dwelling ❑ Secondary Dwelling ❑ Accessory Structure ❑ .Commercial ❑ Minor Remodel -<500 sgft ❑ Major Remodel >500 sgft. ❑ New Structure ❑ New Plumbing Existing # Bedrooms: Proposed # Bedrooms: Existing: sgft : : Proposed: sgft Project: ❑ Barn/Cabana/Gazebo/Solar: ❑ Deck/Paving/Landscaping ❑ Swimming Pool/Spa ❑ Other: I APN: Lot. Size (acres): Street Number Direction Street Name Street Type Cross Street: City. Zip: Phone#• Domestic Water Supply: Proposed Well ❑Existing Wel(s) — Oty? Water Source: Access Restrictions: ❑ Locked Gates ❑ Dogs -[]None ❑ Other: Property Owner: Address: Phone #: City: E-mail Address: Contact Person (Desig State• Zip: Fax#• Business Name (if any): E-mail Address: Address: Phone #: State Zi Fax #: ❑ Same as Property Owner By signing this application, authorization is granted to agents of the Department of Environmental Health to enter the property during normal business hours to conduct any necessary investigations related to this application. Owner/Authorized Agent*Signature Print Name Date ** Office Use Only ** Comments: Owner ID: Facility ID: UU Specialist Name: Plan Type: ONO #: City Code: Submitted: Name Date Received By: Assigned To: Amount Paid: Check Number: Account ID#: Invoice M Plan submitted by: ❑ Owner ❑ Architect ❑ Contractor ❑ Designer ❑ Other Project ID#: SRO Program Element(s): 02113 y � DE.�QR7R1ENT4F�NVIRONMEt�i'Al.Fil=t1LT(i � �;` EONSURIEE3PROTEGTIQNBIviStoN' =Count *.5 ntad3m 7555BergerDr;`Suite50R,SartJosue,CA95412274& ,:. _ _ . _ _ _, {4Q8),918 346(1:..FAX {408)'258-5851 •,�urw.EHatioari� !,'CEASE N07F ; Atlach3�srteplans shQr�ing fhe proposed work Pe{itrt rs yard for � year from tlate, of rsstlance O l7Pro>p %.-.: r orma#lora v z tuner 5,+.i.,.>�a ,. y�ln �f W z z ry' . r. Will -'Add resa _. ._ - Stte Address Crty2ip.- -Cityp .; PhoneStreet; µ F„,J J - - Square;Footage of,Restdence., - Totai,Nprnborof Bedrooms: ❑ New system Existing Dratnfietd to be used ❑lees No Cj Repat hiodiN ewsting system Neu Tank ❑;:Yes, - ,. Na:. T�tew'.Dralneltl : Linear Feet �' TankSize/Manufaciui er : .., -- --._ ;_ .. ... m °° Rock Opptt ;'below pipe.. Inches 1�1eVv Diversiori'Vaive:'sQ.Yes,[} No Chainbersystelrt._0 Yes No " 'r•i'eaS"A','+.. Ai- 1 v te:''i ,� ,."4-'dY '{^ .off".,"': 'r,ro»i .Ye..•..:v".is.t '.. y,( f.._M a R «. f+ "�'4'S 2f h7c '3's 'i t£taft'yi iyrE_Y .J •,. �,- Owner willf provide :the laborand tnatenals for consirucftc�n of the proposed septic system, lm#ial h4r to confttm that the owper has reads the Owner Buttcter tnforniattort, see reverse side of this form ; _,i ), . _ .... . ,andwilt abide b->tiiea'e. uirements -.... _, _: _.. :; 4 ;® Oti+finer has contracted with the following person _9ffipar y to provrd: the con 'ti uctio Addie"ss Contractor's License .: lVofe, No€Ifjrfhe pEH dr_strrctspeclalrsia mrnimum of 1 tvorkirg dayprror#ofhe starofsepftt: sgsteininsfallafrort,; `t agreeahat ail'work is to be completed per stamped, approved plansunlessmodfied during construction bythe Uepartment'of Environrrier tal Hei lth..As-owner or autt oriied agent,.;l represent, #f :at the nformaf►on_herein aubiitided is'correct;to the<tiest:of. my knowledge. . "_Owner/AuthonzedAgenf Sign ature — Pnnt'Narne Date ?ago 1;of'2 SepUo System PerRntP?pftcaifon ?J08,. 0W .1 Fl- . D?ER.INFOkMAT ON "th'&'b6il.ddr'-.`of the, riffa 1 6 tor . s_are required by lawA6. be, l6eqs64;q4b 6 8 6 th- a,: bu'sflhie'�s I! bense-frbhi, on e e: Stato� bi _61 .city tM th dl- d Pr:_qouh.y.-, thpis,�� yttamcons c. ok.am., I "t.60uire' by law epai,r;prip� a po;� Environmental, s pp P*p Septic System DUPIElh to do Y,6urown-worki.,wiihi'th6exception ..'of'. b-- t 4 -you" plan osu cson r'a should following tnformatton;.for yourb en d p-pfq7qff • e, engage, any personst er than your tmrriiedta#efamtly, and the vrork {treludmg: materials and other lf-ypq,,,�pMo :-or.otherwib costs} is $5l}Cl or more for the: entire project, ,thd;personslare:n6t ii'c""ens-e"8.'inr` 't---' kap, ors or subcontractors, on May, bean ;,om, p to er y • yate'- over pdari emD I re stbe,'withlhi4,satean Pm, n6vpmmphf'm-,,.,sry PmnlnxjPr'mnN um vz;rsw ,W9ftr qqmpQnqaV6nin urzncb,.,disabjlityih�dtahc elists andunemploymentnpldymen compensattonrcoritniarafions. There may bq:arlciai.'� y obligati -ns,, "1 -and hese nsks are especraliyserrous_wirh ,resp, wor�qpmpensab' HEALTHCALIFORNIA AND SAFETY., CODE 'S ECTION.S1983049832.1 1983.1i Abity candi536 pec 9832, A; city id city or -60d h rs;requttred to give notice pursuani to Sectton>'19�30_;.shall'attach tosuch notice, and, as:a, 3;cation 48�e q6p6rm#j, 0.0;, -th pqqMp :T r the 1ption.jaro,ypp p return; A ri- 0 6hbf6l lawchartered, ---'.shall" transmit the: rioti "d,*0u Section 19836 icq:rp. qqjrq A ltron'required pursuan: o ection! 983 by miito.theproperty pWper_appljop 0',Prjhe rmay ,provide .,t e-hotjic"ei—,pr'thee V_deidatlah-ln' p4§bnto-the pbrsowappying fobthe sept,ic resents identification ftierit-to iddhtify hkns�61f or he rsel 'asAhO prd(Pery The.return: :,)n.. l,.0e..a co,NRIon, pre, .8eniiio. , issuance, of'lhe-,septic; permit:: its fhe.,Iruih:oraocuracy of the declarations' I h' 9 pyee§�,s n'p )n.-,pnd &tdry,lfabilit ynq.M9h m it of, and,cause of action ford6mageqagz!lnst ' on :verifyilue fa 0 tem p t - ion J09° iY Policy Number: CPD f=~i3 02 9P w a" Ora 1[ial fire laces _` Y Revision Pre aced By.:. GLS T. �n�� ATMENVO errvrROMME tT�HNstr Reviewa3d f3 RN , A rovetlCf3' „ A rovaf,Date PoUcy Name DEFINITION t)F A BEDROOM FOR THE PU�tpSE OF Cd3ND1T10NING A'SEPTi, SYSTEM ... 4. 1`... Purpose::and-Scooe .._, K. This' _q 1py memo<v 'I ass�sfi land use staff �n. determmVg in►hat consfi utes a .betlroom or a potertral bedroom when revEewing house'oor plans., 11 Polrcv; k Rooms goare designated as,craff rooms bonus roorrrs, bffrces, :etc, on house floor plans; must ftre eYaluated jfor their po#entrap, use as ;a bedroom:, -, Such rooms fhat *,d f or convenient access to a full bahrooni are te xnect a beatroom for purposes of sizing the drarntrelal; 1=orxarrrpte; rf sers a;.ful! bathroom rn a'i�iallway beside or a few afoor� tloriirn from an; "once»af office room would be cons.afered:as a potenfal.bedroom:, .The: presence: or, absence of;a closet rots nfhe tlefnrngj;feafure of what constitutes a betlroornlpotendd adroom: .Same rooms; wh'ch:,take the_ rr access direct!} from; a ,!suing room 'or entryway,do not hare a bathroom; maybe exempt:,:. : ;111:.: Procedures prior tv stamping the septic design pians for septic permit issuance., a and` use sta0-m At closely review„ the house floor plan to.ensure that 't agrees With the scope of'te prosect {conditions set during building site approval or ` subdiv�s�on); A11 ;theedrooms and pofental bedrooms mist be accurately�denified.�, IV_ Distribution:; AIIi:EnvironmentaltHealth .taff:and Intranet Ct?.U:NTY, OF::SANTA tLARA DEPAI2TAIENT OF EtdVIRONMEtMT�it HE!!ii,tFi Policy?Name ;SiZlNGDE SEPTfC S1fSTENIS;i�R.RESIDi=HTIALCARE FACt_tTiES: :- Poli: Number; cPaw o2 7t?-. =a1: "III;Procedurest! The:folfowirg `represents;themih�murtr suing requirements for residen�iat care=facilities: . Iy when ho addition to the house is proposed The size of the system;;must them be modified to meef 'the minimum [engtode tirequirements: A repaiC peCmit wil[ be requu d to install a larger #ahk, acid any` „tadditionalieachbnesas required,, -- ., _... _ b) septic systems foC'-stew constructron must be conditioned usmg=the5requited site assessment, test,pit, and percolat►on test. lb tests such as we`t weather testing, . 4 Fnayatso lse_requ�ree'; _ c)When: the septic system is old, or when a major modificaUbn orartenscation o#use:; is.proposed,_the sepfic system must be reviewed and conditioned as anew system.; septic system 'design, for a residential care facility with between ix and twelve ambuiatoryresidents; and at least two caregivers will ire sued with at least a 3000 gallon tank„antl a' teachfietd sized to accommodate the number of resident .bedrooms plus the •bedrooms'for�careg�uers,. -. . _..... z...:. ......, a) The ”"size ofAhe leachfietd �7tust meet the current code requirements rf the leacitffetd Is existing tt' musf tie evaluated tzy a iteensed sep',...' System contractor or pumper: This ;applies a0 septic sysfems that{are relatively nw,. and when no atltlt6ort 'bduseils,proposed .', .,A"-' -'I"- -,T�pa r oe and';any .Sbo -StL_M5 or,ne,wton!uAl6rnu"s"t".be'-'t'-p' ndito'n'td"using';-h'ereq rbed "si� assessment test pit, tifid�g fW616h test' Oth&,;Ag W,dhr`a�-wod 6, ertda ...When the septic .system is^old, �orwh when a.,-,.mayor modification Jdflht6hNfl blil"9, of use eptiotp AZlelT,5.requirements:- - -: ,f6eldWb6tfb'lcare -"-facilities ---tlh _ti.',kW more non am -b'u - a o residents shalld6 bir�iQ,&t4;b'bTh-tank—be at t66 0 0 gallons for those facilities that are expected to hhifi- thari'normat volume of waste kTM LEACHFIELMSY EMS designThe "Sidewinder' prow. -dd'it.qna"Fihflft& I,-are--''a-".Atthe"s idd IL Tide suing pp", tationrequlr qrylqn. Is�j"AWuse e*. any :,�,� rem, in : lnfltrator;,motlett nso fth-As lll'a`� JR P.: 1 -D'.00 -6P-7 AM F p �pp kTM LEACHFIELMSY EMS designThe "Sidewinder' prow. -dd'it.qna"Fihflft& I,-are--''a-".Atthe"s idd IL Tide suing pp", tationrequlr qrylqn. Is�j"AWuse e*. any :,�,� rem, in : lnfltrator;,motlett nso fth-As lll'a`� Pollc 'Nu mber CPD -LD o2=2P-A, Policy Name APt`+�tI�VED CHAMBER MAC HING,!§Y-,,t S 1.; Aur�ose acrd Scorse. affP, nV-P 11" '-d A te t, leaching If continues to ;be lh '57 PQpor-f�e, ft lo�_ ,�,pprpv66 Y 'o''APd �nsta/la#torr of only PrAy; RM4 that prov s p aapacy ine "Pr iiii 60 iOV4 �t ich- hp�oi- in S,"--S'te or .y I p '�dl "of 6, 199RY Four ,.,.,n w" u1. Santa Clara Ise.. -9- pp is ro lhe'. owl e _0 . d. - _p - —d Hancox Standard h wf .6. bdii4 ro hgth same eusso,o'.1 ;all _�j any; sizinglaflibn� requirements s remain the per,inch is n, -Qt.,,,a Policy Number, CPD=LD-.0Z.3P: OriBttaal "Iacsa ` LD:P_ PreparadBir, GLS< lAkk A F-_ aep�trna�wra��nv�ar�rta _ ,. ... ,. - ARM APPr+Dvaf_Date. Poh Came. Subdlvlslon cy , ,lplicai�on Processing-Sepitc:Systems: l ; ,Pur aoswand Scone: v Thal informai�on is an uptlate of the procedar for processing land; use applicat�nrs for subdivs�onsof-`iand:.: - . t# eon#�nues fo: 6ethe policy of thrs Departmen# to'evalua#e �x�sfingsepfic: ' sysfem(s� and esfab/rs�t septic system _condlfrons fornewly-tcreafetl parcels asp part of the`subdtv�s�orr process: ' 111_ Proceduress Each parcel m:fhe proposed sti 1sron-must be evaluated=separately : Sept[c system cond►dons must be established for each uritleveloped; parcel , Each; . developed parcel �nr�lle evaluated fo cleEemnihe, if. the existing septic rsystem{s) meets thecequied .sefbacks,,and~whetherthe system,is funettornngadegctately,;" Existing septic systems that rneef the setback regdIremer',b are found functioning adequately, but do no{ tree current sewage ordinance requirements may. continue to`be used without matlificafion provided theca �s si�ffcientarea;for expabsron_in„case of failure of .remodel :to:-the.:hause lY Distnbufion = A!t_ Win 0nmental k WiffilSpecialists_and'DEi l kand r :T Policy Numberr GPD LD Q2 5f' a Original -_ Replaces Revision '#"1 OF SANU Cl. Pre staid B GLS _ Rev�ee�►ed B "R+IF A.... 1oVeii Approvai Dafe. l� 3l �0z Policy Narne Cornptirt�ora of spt,c systefn as-buiifs I: Purp'ose.aft ci_tS M lit tiely compte#lon, fte,ptic system :as bunts ensures `:that necesaiy �r►formatton .w�tl be a�a�labte for review It is essential, that the conplated system as built be; :available soon after,system comptetton Ready`access to the cvmpptd as biiit cMl facila# venfication that the Sys#em has ,been finalted, such as might be required for `final occupancy sign off, and pro'I mprovetl ,tum aropnd time ;for septic :clearance for future projects.; such_as`.eswlmmIb g pool mstallattonr anc�lary �sfructures,tetamtrg walls,, ate 1t: :Policy. D�stnct staff mus complete the septrc system as buil# w�#hrn0 working days.o' f he compiePion and,frost `of.the; sys`tm.- Proceci&es'; `Land' use staff will comprete the as bujtt, organize the septic permit file in#orrnat�on, and submit the completed work to ilia distr�c# office srfpervasor within 1Q marking days. of fhe:f nal, oi" the .septic system., Iff Distribution: All Environmental Health Spec�ahsts; and, DEH liirartiet. COUNTY OF :SANTA CLARA DEPARTMENT OF ENVIRONMENTAL HEALTH Policy Name: Pump systems Policy Number: CPD-LD:04-04P Original Replaces Revision: LD:91-3 Prepared By: GLS Reviewed BY:: RJF Approved By:: Approval Date: L Purpose and. Scope: As the number of easily developed parcels dwindles it becomes increasingly important to ensure that septic systems are constructed in the safest manner possible for the protection of public health and safety. This policy establishes revised guidelines for the approval and installation of.effluent pumping systems. II. Policy: All land use staff must use the effluent pumping guidelines when reviewing an effluent pumping system. The packet should_ also be distributed to owners/designers for use in proper system design. Ill. Procedures: Field staff will use the work sheet to ensure.that.the proposed pumping. system meets all the design criteria. The checklist may -be used to determine if all required materials have been submitted, and all issues related to the pumping system have been addressed. Once the field specialist has completed his/her review all the pump' ystem materials are given to the Supervising Environmental Health Specialist for review and approval. Once the septic system plans and the pump system have been approved, the field specialist will stamp the septic design plans with a -conditional approval. The Supervising Environmental Health Specialist then signs the plans, and the plans are stamped (supervisors should use the existing_ stamp) indicating that the qualified designer and a DEH representative must be on site: during the pump system testing. IV. Distribution: All Environmental Health Specialists and DEH Intranet SANTA CLARA COUNTY ONSITE SYSTEMS MANUAL PART 2 SITE EVALUA NVESTIGAT ODS AN® 'LEMENTS : Onsite Systems Manual - Part 2 (9/2013) Page 1 SITE EVALUATIONS FOR ONSITE WASTEWATER TREATMENT SYSTEMS A. GENERAL Prior to approving the use of an OWTS, a site evaluation is required in all instances to allow proper system design and to determine compliance with the site�`suitability criteria identified in the Ordinance and this Onsite Systems Manual. f, For new divisions of land, soil profiles, percolation test 'andgroundwater determinations will be required on every parcel unless the director termines, on a case by -case basis, that such testing isnot necessary due to -the availability ofifficient information,to,demonstrate conformance with applicable siting criteria for all -proposed OWTS location's Site evaluations shall be.conducted by a -.qualified p accordance with the following requirements and rE For sites where a conventional OWTS is'apparophat( evaluation may be conducted entirely by Col staff terrain): and for anyFs to req ing th,,e use of'a'- to system design will require the involvement of a'n 0'. geologist, or registered�environmental health speci percolation "testing -shall be oc nducted by'or,der consultant�.,Where.,t a work is conducted by ikon: site evaluation to coordinate withand allow forgiver N- and evaluationsshall be made in :achments. the site assessment and soil profile For more difficult sites (e.g., steeper dative OWTS, the site evaluation and ITS consultant (civil engineer, professional list), who is retained by the owner. All ie direct supervision of a qualified OWTS Jtant, the DEH shall be notified prior to the :ication by department staff. - B. SITE ASSESSMENT The first step in the site evaluatio°process is a preliminary review of the physical features of the site by DEH staff,4ncluding the slope of the land, proximity to cuts, steep slopes, watercourses and dramag--swal s, wells, and other features that may limit the available .4 =: dispersal area.' Prior to conducting the site assessment, a Land Use Application form must be completed,.along with a preliminary site plan. This form must be signed by the owner of the property in order to gain access to the parcel. Site features determined by the field inspection and review of available maps and file information include: Onsite Systems Manual - Part 2 (9/2013) Page 2 (1): Land area available for treatment components and for primary and secondary/reserve dispersal fields. (2) Ground slope in the primary and secondary/reserve dispersal area(s).,. (3) Location of cut banks, fills, or evidence of past grading activities, natural bluffs, sharp changes in slope, soil landscape formations, and unstable land forms within 50 feet of the primary and secondary/reserve dispersal area(s). (4) Location of wells, watercourses, drainage swales and,.oth`er bodies of water within 150 feet of the primary and secondary/reserve dispersal area(s). (5) To the extent possible, the location of existing�OWTS within 100 feet of the primary and secondary/reserve dispersal area(s). Following the site assessment, a written report describe any limitation to development of the s C. SOIL PROFILES - After the initial site assessment, soil condition` require evaluation through oil profile observz backhoe excavation or soil boringAo a depth e bottom. For conventional OWTS; the backhoe below trench bottom;�for alternativ, OWTS t trench bottom. The purpose of the soil a -r He is to be provided by DEH ,The report will briefly isine an OWTS. �area(s)dbn,�tified for the dispersal field soil profile*typically consists of a gbeloyu the anticipated dispersal trench tion should extend a minimum of 5 feet h may be reduced to 3 to feet below (1) Determine the suit l i ty of the oils for absorption of wastewater in the dispersal `orae trench�zone- and N (2) Verify that`there, will be adequate vertical separation between the bottom of the dispersaltrench an , _, d bedr, ck, groundwater, or impermeable soil strata. F A minimum of one excavation in the primary dispersal :field and one in the. secondary/reserve area shall be required for this purpose. Additional soil profiles may be required if the initial two profiles show conditions which are dissimilar to the extent that they do not provide sufficient information for design and/or determination of code compliance. Auger test holes may be an acceptable alternative to backhoe excavations where the DEH determines either that: Onsite Systems Manual — Part 2 (9/2013) Page 3 (1) the use of an excavation. vehicle is impractical because of access or because of the fragile nature of the soils; or (2) it is necessary only to verify conditions expected on the basis of prior soils investigations; or (3) it is done in connection with geologic investigations. Also, where groundwater separation of more than 5 feet is required (e.g., for conventional OWTS in areas of rapid percolation rates), additional (deeper) subsurface exploration maybe required for groundwater determination; and this can bed, ne with an auger boring rather than backhoe. excavation. The following factors should be observed and reported from groui soil profile: o. Thickness and coloring of soil layers, soil structure, and States Department of Agriculture (USDA):classific`4tion Depth to a limiting conditior� uch as.,hardpan, rock strz A." saturated soil conditions. ® Depth to,obse d groundwateK., to the bottom of ing to United ta, impermeable soil layer, or Depth to an`d d'escription�of soil mottling (redoximorphic features). • Other prominent soil,features�th, whimay affect site suitability, such as coarse fragments,tp;15istence zroots and"pores, and moisture content. X Soil profilleinspections should follow guidance provided in manuals such as: (1) IJSDA,Natural Resources Conservation Service. _ "Field Book for Describing and ,l Sampling Soils"�\Septem be r 2002. (2) USEPA "Design Maanual - Onsite Wastewater Treatment and Disposal Systems". 1980. (pages 28-38). Various aids for soil profile observations and logging are provided in Attachment A. D. DEPTH TO GROUNDWATER DETERMINATION The anticipated highest level of groundwater in the primary and secondary/reserve area shall be estimated either: Onsite Systems Manual - Part 2 (9/2013) Page 4 (a) As the highest extent of soil mottling observed in the examination of soil profiles; Or (b) By direct observation of'groundwater levels during the time of year when the highest groundwater conditions are expected or known to occur, i.e., wet weather testing period as defined by the DEH. Where there is a discrepancy between soil profile indicators (mottling) and direct observations, the direct observations shall govern. If there are site characteristics or historical docum is likely to occur during the rainy season, a wet we required. This investigation must be conductedfdi conditions in accordance with DEH policy and.;proi be contacted early in the site evaluation processii observations are likely to be required for a partcu E. PERCOLATION TESTING M*,� Percolation testing.is conducted to confirm the'gr proposed site and to determine the size of the dis must hire a consultant to'cond ctthe percolation oversight to be provided during the testing \P,erc accordance with proced,u'res detailed in Attachme With m testinel (1) Contracting with an`OWTS cc upAelpercolation test holes OWTS'',consultant; V- } moi- •� .Y: entationrindicating that a shallow water table atl er&groundwater investigation will be it g normal wet weather ground water e ures (see Attac'h'ment B). DEH staff should determine if wet weather groundwater lar\site and'to coordinatethe work. -applicant is; idwater separation requirement for the sal field for"tKepro ject. The applicant 'ts DEH -will determine the level of tion testi6 shall be completed in C. esoonsible for: ctor or other qualified individual to excavate and set - cations designated by the DEH and/or the applicant's (2) Contracting -with an OWTS?design consultant to. run the percolation tests; (3) Making necessary arrangements to assure that adequate water is available for the required .24-hou pre soaking and for refilling during testing. Percolation testing will noriim'ally be conducted at the time of or shortly following the soil profile investigation. However, if the soil profile observations indicate the presence of expansive -soils with high shrink -swell characteristics, percolation testing during the normal wet weather season will be required. This is because expansive, high shrink -swell soils may exhibit suitable soil percolation rates during the dry season due to shrinkage cracks in the soil; but, when they become wet, the same soils may swell to the point of providing little or no percolation. Field judgment of the need for wet weather percolation testing will be made based on: (a) visual evidence of soil shrinkage cracks; and/or (b) soils exhibiting high clay content (e.g., exceeding 40 percent) in combination with massive, columnar or angular blocky soil structure. Onsite Systems Manual - Part 2 (9/2013) Page 5 F. GEOTECHNICAL REPORT/SLOPE STABILITY ANALYSIS For any site where the ground slope in the proposed dispersal field area exceeds 20%, and for recommended reduction in horizontal setbacks from cuts, embankments, steep slopes or.an unstable land mass, additional geotechnical evaluation of slope stability, drainage, and other factors shall be required to verify that the proposed dispersal system will not degrade water quality, create a nuisance, affect soil stability or present a threat to the public health or safety. The requirements pertaining to this additional geotechnical ev l ation are further detailed in Attachment D. G. CUMULATIVE IMPACT ASSESSMENT For certain projects, typically non-residential and large flow OWTS,�the-completion of additional technical studies, termed "cumulative impact. s' ssment, may re"be `' u ri ed. This is to address q the cumulative impact issues (mainly groundwater'mounding'and nitrogen:, loading) from OWTS that can result from such factors as the con stituerit;levels, in th°e; wastewater gf, nitrogen content), the volume of wastewater flow, the density'of OWTS discharges in a given area, and/or the sensitivity and beneficial uses -of water resourcesNn a particular location (e.g., proximity to vernal pools). These issues are not necessarily`addressed by conformance with standard OWTS siting and -design criteria r > Cumulative impact or more.- �ssment is. man Cumulative.impact assessi type of/system (conventio director -for, certain:situa"d The requirements and gui detailed in Attachment E. H. REPORTING wit wastewater flows of 2,500 gpd ent is `not required for`nor7nal residential OWTS, regardless of the al or\alternative);,except-as-may otherwise be designated by the ns of geographical areas of the county, elines,pertaining cumulative_ impact assessments are detailed in All site evaluation information, including soil profile and percolation test results (and map) for primary and secondary/reserve dispersal areas, geotechnical report (if required), and cumulative impact assessment (if required) shall be submitted _to the DEH with the OWTS permit application. Onsite Systems Manual - Part 2 (9/2013) Page 6 DEPARTMENT OF ENVIRONMENTAL HEALTH A ? CONSUMER PROTECTION DIVISION J J 1555 Berger Dr. Bldg., Suite 300, San Jose, CA 95112-2716 County of Santa Clara (408) 9183400 • FAX (408)2585891 a www.EHinfo.org SITE ASSESSMENT REPORT Site Address: Assessment Date: City/Zip Code: ON#: APN: ❑ Existing Septic Permit (SP#: ) Items marked below represent constraints to designing a septic system or information that is required to determine the feasibility for designing a septic system on this property. This report represents a preliminary review based on a visual inspection of the property. It should be used only as a guide for more in-depth evaluation of the property for development. 17, 1Before proceeding with.soils investigations, it must be demonstrated on a site plan that at least + lineal feet of drainlines (plus 100% expansion area for properties in Lexington Basin) could be installed. This is the minimum system (for a 3 bedroom house) that can be installed if very good percolation test results are obtained.. Percolation studies may dictate a larger system, which may preclude development.. E:12. It appears that the slope on a portion of the property exceeds 50%. Drainfields may not be installed on slopes that exceed 50%. In South County areas, approval by the California Regional Water Quality Control Board - Central Coast Region is required for drainfield located in areas that exceed 30% slope. Submit a topographical map and survey showing 2 -foot contours. . ❑ 3. It appears that the slope in the proposed drainfield area will exceed 20%. Approval for the use of a septic system will be contingent upon, submittal of an engineered plan and a geotechnical report that demonstrates that the specific septic system design will not result in soil instability, surfacing effluent, contamination of water or creation of a nuisance. ❑ 4. Existing or.proposed easements or rights-of-way (driveway, roadway, etc.) may limit the available drainfield area. ❑ 5. Soils test pits and percolation tests must be conducted under the oversight of this Department. The results of these investigations will determine the suitability of the soil for a septic system and will determine the required drainfield size. F16. Cuts and steep banks (for driveway; house, retaining walls,roads, etc) downslope from the proposed drainfield (either on the subject or adjacent property) may limit the available drainfield area. ❑ 7: Wells located on the subject or adjacent property flay limit the available drainfield area. ❑ 8: The watercourse/drainage Swale on the subject or adjacent property may limit the drainfield area. . ❑ 9. Large trees on the property may limit the available drainfield area. Maintain a setback of at least 15 feet between leachlines.and trees over 18 inches -diameter (when measured at a height of 48 inches above the ground). . ❑ 10. The proposed drainfield may be subject to seasonal high groundwater. A wet weather groundwater test may be required. Contact the DEH Land Use Senior at 408-299-5748 to be placed on the wet weather groundwater testing window notification list. ❑ 11. There appears to be considerable surface drainage onto the proposed drainfield area. ❑ 12. There is fill in the proposed drainfield area. A maximum of 1 foot of fill is allowed over a drainfield.. . E3.13. Subject property is located in: ❑Lexington Basin Subarea ❑Los Altos Hills ❑South County ❑ 14. There may be unpermitted or illegal structures on the subject property. ❑ 15. Other: For more information regarding the septic system approval process and design requirements, please see Bulletin A, available on our website or at our office. . Specialist Date Sent to ❑Mail 1 [:]Fax/ DE -mail 4109 L .! Sandylotim 0,10a iooft) OaY TABLE 3`=4; WPM �'P_ its single graj Jh_ y. po , ► p fe-el, hand, the apart" pressure -d Aggregates -- :r very #arnt+elrrety f 4g, 1- A - I n i J, a, rubbing tht, grlttyfoe Eng, of sand and. -soon. dppqptps�- b4b't.: rha"_ _Y b h d� -'d moderate_''`- pressure I. Clods are firm to hard. Smooth, flour like feel dominates when pulverized:. :crush ng by hand':; di it' ""Nm has :a ,g,r t►ke:atextu:re due to. the har�'fi f OU Oi n:6$s of numerous= very;, small aggregates: ._-V tch: , Squeezed1h It .... . �', hand, forms � -cast which whtouched.en Does; not.forrn -l-, p"J'Ab., 9- b9iWYPIPP, PRib and;: 'T .�q - r. Forms a casf .which... bears; careful. handling without, rq�a pjng Does not farm :a j ribbon tetwee.n thurrib and . �fojrefinger,, Cast ears b l5 4i�qs�."19P;-,b' handled` ft :," quit e freely —H h't t' � t§11 9_1 tendency �t, ribbon between thumb anet fo�reftnger,Rubbed surface. I r Cast'31 -It �6 b ij without break ng Sight z.)9_ tendency�,.,,§tp,,:T 66.6n thumb d fo�r;ef►nger Rubbed,; surface has a -bi or iud;handl_ng Pinched`.: and ?ems. a P, pil mogv PJI when dampened Iles; ess:ily; As scan .`4ew, ;co*l.,de,Ob'(..e� dIijjg';.wi.lho'ut bre kjP A 'g' ob, 71 ns :a J:l'e-Xlb.l,e-, rl6hqq veer ,thumb; ,and forefi1mg.-er me onga e f- - . has ;�a very;. in ,feeling:. Sti`dky.-:4h6n, ,:puddled::; Sand., A %. ATTACHMENT. B Department of Environmental Health Consumer Protection Division 1555 Berger Drive, Suite. 300 San Jose, CA 95112 .408-918 4400 COUNTY OF SANTA CLARA Of VMTYg_trt OR EYneOrtY ENLU. YlFLTH SANTA CLARA COUNTY INET WEATHER GROUNDWATER INVESTIGATION Background The Santa Clara County Sewage Disposal OR investigations be conducted on each building �4 sewage disposal (septic) system. One�fiunetio determine if there will be adequate separation leachfields and seasonal high groundwater for ordinance requires groundwater to be at least that exhibit moderate percol tlon`rates, and 2( For alternative OWTS a.2 to foot separation Itriancerequires that soil lite to be seined by an onsite i of these sollAnvestigations is to between the bottom of the. conventional systems'. The 5�fedt-b low the leachfiel�d in soils �feet,ifhighly permeable soils. t&d*ndwater is required. Failure to provide the required septi ationto seasonal�ilgh groundwater may, potentially result in'gr ndwater contamination from the eptic system or failure of the septic sys{emitself'septic system fail& e cid manifest itself, among others, by effluenturfacingg,60on the grou nstandand/or sewage backing up into the house fixtures. Illing a septic systernon a site that appears to have adequate separation. to groundwater�rn the dry season- but experiences shallow groundwater _durmg therain season may result in a septic system which functions property only pa ofthe year:, The Department of Eftirenmental H, ealth (DEH) has developed a policy that describes -the we. weather groundwater investigation process. This process is used to identify., sites witi�_el'evated seasonal groundwater tables which may preclude development using onsite _sewage disposal systems. . A seasonal groundwaierjable may suspected where 1) previous soil investigations have iridicated evidence of high groundwater (soil mottling); 2) the site is at the base of a hill, near a creek or otherwise located where water is likely to accumulate;:3) riparian type plant life is present indicating prolonged soil moisture; 4) the Santa Clara Valley Water District (SCVIND) records indicate higK groundwater conditions in the area; and/or 5) the presence of any other condition that may indicate a seasonal high groundwater table. Page 1 of 2 Wet Weather Testing Rev. 2-17-09 Wet Weather Investigation Process A typical wet weather investigation will consist of a test pit, or with the approval of DEH, a test boring witnessed by DEH. The.test must be conducted when sufficient rainfall has occurred in the area to establish the normal seasonal groundwater table. Prior to. conducting the wet weather groundwater investigation, the percolation rate of the soil should be determined by DEH in order to assure that the wet weather investigation is conducted at the proper depth. DEH uses data from four SCVWD rainfall -monitoring stations to determine when sufficientrainfall has occurred. The testing window will open for. a 30 -day period when at least 60% of historical seasonal average rainfall has occurred, and -14% of that average has occurred in the last 30 days. The window will be extended for two-week periods provided that at the end of each testing period at least 14% of historical seasonal average rainfall has occurred in .the previous 30 days. In lieu of test pits or borings, the applicant may: choose to construct at least two test wells in locations specified by DEH. The wells must be constructed to the same depth as: would be required for the test pit. The wells must be constructed by an individual or company knowledgeable in the proper construction of these wells; and approved by DEH. The casing must be perforated from four feet below the surface to the depth of the well and the annular space at the surface must be sealed to prevent the introduction of surface water into the well. DEH will monitor the well during the wet weather investigation window. The District Environmental Health Specialist should be consulted to determine whether a wet weather groundwater investigation wouldbe required on a specific site. Appropriate fees must be paid to DEH prior to conducting the wet weather investigation. Wet Weather Test Alternative As an alternative to conducting the wet weather: test, the applicant may elect to retain a hydrogeologist to. investigate the site for evidence of seasonal high groundwater and submit'a written report to the Department of Environmental Health. The investigation must include a field examination of test borings or excavations in the drainfield area and must address the topography and drainage of the area, including surface and subsurface drainage. Borings and excavations must be extended from 2 to 20 feet belowthe bottom of the proposed drainfield (based on the percolation rate of the soil and the type of OWTS proposed). The report must be submitted to the Land Use Senior who will request that the County Geologist review the'report and comment. The County Geologist charges a fee :for this review. Contact the County Geologist at 408-299-5774 for the fee schedule. These requirements should be discussed with the Land Use Senior at 408-299-5748 prior to conducting the investigation. A fee is also required by DEH for review of the hydrogeologist's report. Page 2 of 2 Wet Weather Testing Edited 8-20-13 ATTACHMENT C ENVIRONMENTAL RESOURCES AGENCY DEPARTMENT OF ENVIRONMENTAL HEALTH CONSUMER PROTECTION DIVISION 1555 Berger Dr. Bldg., Suite 300 • San Jose CA 95112-2716 County of Santa Clara 408 918-3400 • FAX 408 258-5891 • www.EHinfo.org SANTA C LA RA COUNTY DEPARTMENT OF ENVIRONMENTAL HEALTH PERCOLATION TEST PROCEDURES CONSULTANT CONDUCTED TESTS The person verifying the validity of the percolation tests must attest, .in writing, that the test was set up and conducted in accordance. with county standards, including the presoak procedure that he/she personally observed the site and at least a portion of the tests. - Test results shall be submitted on forms provided -by or equivalent to those provided by the Department of: Environmental Health. Aug 2013 Edits ATTACHMENT C General Information Percolation tests must be conducted by or under the supervision of a California state registered environmental health specialist, a California state registered civil engineer, or a California state professional geologist. The-.Dbpartment of Environmental Health will review and approve the number of percolation . holes, their depths, and locations. Department of Environmental Health staff may elect to witness the installation of the percolation holes,.verify presoaking, and be present during all or part of :the testing. Upon satisfactory review -of the data, department staff will determinethe appropriate leachfield length. A base rate will be charged for the first IY2.hours. Extended service will -be charged at an hourly rate. Contact this department or visit our website at www.ehinfo.orq for our current fee schedule. The consultant shall notify the :appropriate Department of Environmental Health office at least 24 hours prior to installing the percolation holes and 48 hours prior to conducting the percolation tests. Percolation tests may be conducted Tuesday through Friday. Test readings are to be submitted on forms approved by the Department of Environmental Health. Hole construction (seethe attached diagram) Diameter —12 -inches Pipe Size — 4 -inches Depth as determined by the Department of Gravel Size -'/2 to % inch clean washed:drain Environmental Health. rock. Number — the minimum number of percolation holes shall be 6 per site. Additional holes will be charged at the same rate as the initial 6 holes. Only those holes agreed upon prior to the test will be used to determine the leaching system requirement. Check with your local Department of Environmental Health office for more details. Pre-soak Percolation hole locations must be reviewed and approved by Department of Environmental Health staff prior to presoaking: A site map, showing :the location of all percolation holes must be maintained by the consultant and submitted with all percolation test readings. All percolation holes must be pre-soaked :before the test begins. Pre-soaking is to consist of filling each percolation hole to at least 6 -inches above the test fill level, two times (once in. the morning.and once in the evening) the day before the test. Filling each percolation hole is best accomplished by adding water through the pipe rather than into the gravel. Materials Adjacent to each percolation hole there should be a hose connected to a plumbed water source or a water filled container of 5 -gallons or larger. Fifty (50) gallon drums or garbage cans are often preferred for faster percolating soils. A water =truck or other water source is to be available for refilling containers -as needed during the course of the percolation test. During the percolation test, holes may best be filled and re -filled- to 6 -inches above the gravel bottom by using a small, easily managed bucket of/2 to.1-gallon capacity. ATTACHMENT C Test Procedures (for use with attached percolation test form) 1. On the day of the test, if more that 6 inches of water above'the gravel bottom remains in any test' hole. This constitutes a failure; and no further testing of the hole is warranted. If less than -6 inches of water remains in the test hole, proceed with steps 2 through 7. 2. Carefully fill the holes to 6 inches of water above the gravel bottom. 3. .Measure the distance from the top of the pipe to the water surface with a 1/8 -inch accuracy. This is water surface measurement A ("Start"). Record the measured distance. Record the time. 4. Allow 30 minutes to pass. 5. Measure the distance from the top of the.pipe to the water surface with a 1/8 -inch accuracy. This is water surface measurement B ("Finish"). Record the measured distance. Record the time. 6. Determine water level drop. The water level drop is the difference in inches between water surface measurements A and B ("A INCH"). Determine the amount of time between Start and Finish readings ("0 MIN"). Calculate the rate in minutes per inch (MPI) as the product of "0 MIN" divided by "0 INCH". 7. Refill each hole to 6 inches of water above the gravel bottom and repeat the procedures of steps.3 through 6 above. 8. Continue these water refill and water level drop measurement procedures fora period of at least two (2) hours and until the water level drop (step 6) stabilizes and three (3) consecutive water level drop determinations are within 10% or 1/8 inch of each other. Note: The water level must be readjusted to 6 inches above the gravel bottom after each reading. 9. If after one hour the water level is dropping so rapidly to make 30 -minute readings infeasible, switch to 10 -minute readings. Refill the hole to 6 inches above the gravel bottom and repeat the water level drop measurement procedures (steps 3 through 6) using a 10 minute interval instead of 30 minutes. Continue these 10 -minute tests for at least one hour and until the water level drop stabilizes and three (3) consecutive water level drop determinations are within 10% or 1/8 -inch of each other. 10. All readings are to be reported in minutes per inch-.. 11. Complete calculations at the bottom of the percolation test form. by: (a)entering the final stabilized rate .for each test hole; (b) multiplying the stabilized rate by 1.4 to adjust for the displacement of water by the gravel=pack; and (c) calculating the average adjusted stabilized rate as the sum of the individual results divided by the total number of tests completed. 12. The average percolation rate determined per step 11 is used as the basis for dispersal system design and for determination of applicable groundwater separation requirements. See Additional Notes for dealing with individual outlier percolation values; including excessively fast, excessively slow or out -right failures. 1 13. Data for all percolation holes must be submitted to the Department of Environmental Health for evaluation. This data is to be included with a copy of the site map showing the location of the numbered percolation holes. ATTACHMENT C Additional Notes on Percolation Testing. Number/Depth of Test Holes: • Minimum of 6 tests in dispersal field area (spread over primaryand secondary/reserve) for system design; 6 tests total for each parcel in new subdivisions. • Minimum of 3 tests. at proposed trench bottom; others within sidewall infiltration zone Presoak Procedure: • Required on the day -prior to testing, except: during wet weather period when the presoak may occur on the same day as testing. • Fill test hole to 12 inches above gravel bottom and maintain for 4 -hr period, refilling approximately once per hour. Alternatively, presoaking can be divided into 2 -hr morning, 2 -lir afternoon period or other schedule to achieve 4 -hr total presoak period. Use and Interpretation of Results • Apply 1.4 gravel adjustment factor to determine final rate for each test hole. • Calculate ,average mpi of all test holes • If there is one failing test result, three options are available: 1) Include the failirig result in the calculated average and design the system accordingly; 2) Exclude the area represented by the failing test hole, and design the: system according to the average of the other test holes. Split the difference between the failing and nearby passing test holes to determine the area to be excluded. 3) Conduct additional testing in an alternate area or to refine the exclusion area represented by the failed test result. • . If there are two or more failing test results, additional testing will be required to define the limits of acceptable soil areas for,the dispersal system. xonslper5/00 ERC ATIONTESTRECORDED'. in, _ONVINMI CAM— �'LOCATION7- ...... COWT :..PHONE..:... )DATE', StAfflied'SIPT s e -u A t d Stabia'da-Wil- gq Av�g AOistw sfdbilii cry 00MR. -MY14-1 b.W" r;. nSANTA if Ct]1.1i91:Y .. DEF Y'i Ei�iY' +'ENV Itt)N1YfEN .HEALT]Elk MM "Op TIO 1 Z:. Handiauger 9'r macli ne-Aumpr a 12_ nch hole., 2 5caiiiy the glaze`dewall, it any. 3, Inert the perforatecipipe �n the center ofttee 12 mch hale; 4 GrtaveI-pack the hole around the pipe vnth,!% finch to'l. inch clean; washed:, ravei to:tl e grour►d' surface: Clean wast ed Grgyef Pape Presoi k-10- Tift Il`l- Tesf 4 "s DEPTH TO1�E.APPRb'�Eb - filllevel` .. ri :PYEHS h 14"`:mir% 12:1D',r _c ,St�l!tTr�iG'L�AC�t D�P�R�'-1VlEi�T_�►l' ENi��PNT�13G 1�EA�,TI An TJEIOD OF Ct)O ' ' Y3+CTYO 1 a lslrllorial fee wi11 ke- charged for this:method,o conso(Apn. ;t2. Backhoe excavattcn wsth the iiottom of the .cxcavation;no greater Shan 5 feet: in depth:, 3. Haul aumor mnchihe :auger a i2-mch hole:., �. Scarif�r the ;glazed'siflewali; sf any,,= _ .:5' Inserttt�e perforated pipe iii the center of the 12 :inch dote: 5 Gravel pack the hole around t}ie pipewith %z inch to'l-inch clew n wasW grafi 1. 1'The: eatcavaf ort, shall be:tiack ,filled prior°to conducting ihc.percolation'tct, ; y" r, v21.5', . '�DEPT`H TO -094p Coupler =► 1 fZ" 3Xd" , : - + ,Pxesoak fill level, C�eau Fvashed.gravel �; a PerToraded pipe rr Test fill �Ieve� r, ` �rS��ai i ' • �=� k 1�" 111111,, . 3 L Ptrc7.ppt(5tt)(i}q ATTACHMENT D Geotechnical Report & Engineering Installation Plan Requirements for: Slopes Exceeding 20% ➢ Reduction of Horizontal Setbacks When it is proposed to install an.OWTS on slopes over 20% the County OWTS Ordinance, Code Section BII-83, .requires that it be demonstrated "through a geotechnical repot and complete engineering: installation plan ... that use of the subsurface: dispersal system will,Xnotpermit sewage effluent to: surface, degrade water quality, create a nuisance, affect soil stability, or present a threat to the public health or safety. The geotechnical report shall include, but not be limited,,to soil percolation rates, contours, soil depth, seasonal groundwater elevation(s),location o all a&ting ori ,ro osed round cuts, rock P 8�' f ,, g Pg formations, soil stability, drainage, and other data as, determined by the director and the County geologist. Also, under Section B]1-67(i)(6):regarding horizontal'setback distances betwee"W the dispersal field and cut banks, embankments, steep slopes and unstable land masses the Code allows for (•eduction of the required setback distance "... in accordance with recommendations provided in a geotechnical report by a registered civil engineer or professional:g ologist... The following are the minimum requirements for`the pieparation'of the geotechnical report and engineering installation plan pertaining to &h above provisions of the Code. 1. The geotechnical report -nu pbe prepared by a stag regist reds evil engineer or a professional geologist certi-fi an engineering geologist or%havmg similar geotechnical expertise as determined by the,County geologist. The eiiguieering installation plan must be prepared by a state registered civil, ngmeer professional geologist, or registered environmental health: specialist The xeport`and plan maybe p epared by different authorized professionals. 2. `Engineering Installation Plan Requirements:'.� a) The plan must be�Wet stamped by the designer and initialed or signed.. b) The plan must mchi& cross section(s) through the dispersal field that show dispersal line depthi and details; add any benching that will be necessary to install the system. c) Any OWTS'prdposed for installation on slopes between 30% and 40% shall require the use of pressure distribution methods, designed in accordance with applicable guidelines in Part 4 of the Onsite Systems Manual. d) Any OWTS proposed for installation on slopes between 40% and 50% shall require the use of subsurface drip dispersal methods, designed in accordance with. applicable guidelines in Part 4 of the Onsite Systems Manual. e) The plan must include an erosion control plan, incorporating measures consistent with guidelines and requirements contained in Division C12, Chapter 1H.6f the Santa Clara County Code (County Grading Ordinance). 1 ATTACF9ME6VT D f) The plan shall incorporate applicable recommendations.contained in the geotechnical report regarding the avoidance or mitigation of slope stability concerns, including, as applicable, recommended horizontal setback distance(s) from cut banks, embankments, steep slopes, or any identified unstable land mass within 100 feet the dispersal field. 3. Geotechnical Report Requirements: a) The report must specifically reference the en future date, the dispersal field is appreciably submitted that references the modified plan. b) The geotechnical report must discuss the. ge'( soils, groundwater, drainage,.petcolahon:rat, pertinent site features. ' . c) The report shall include any recomrnendatio. mitigate potential slope stability, drainage, o installation or on-going4,operation of the prof recommended horizontal setbacks) from an any identified unstable land mass d) The teport must state specifically i the cont other wordinW`_such as not likelv'to. riskis 1)"� Permit sewage effluent tallatioji plan. If, at some amended report must be and seismic hazards, vegetation and other ppropriate or necessary to icerns associated with either the i, including, 6§applicable, embankments, steep slopes or on that the proposed OWTS will'not (or ow, etc:):: to the public health or safety nuisance e) The geotechnical report shall be wet -stamped and signed by the responsible licensed professional. 2 GUIDELINES FOR CUMULATIVE IMPACT ASSESSMENT (Draft -August 2013) A. General Provisions. Code section B11-74 authorizes the director to require the completion of additional technical studies ("cumulative impact assessment") for OWTS proposals in situations where cumulative impacts on groundwater and/or watershed conditions are of potential concern. Cumulative impacts from OWTS may occur due to such factors as the constituent levels in the wastewater(e.g., nitrogen content), the volume of wastewater flow, the density of OWTS discharges in a given area, and/or the sensitivity and beneficial uses of water resourcesf(e g.,<proximity to vernal pool). Cumulative impact assessments to address potential'`concerns shall be conducted in accordance with the requirements outlined in these guidelines. The results of the assessment shall be submitted for review by,,the Director and may be the basis for denial, modification or imposition of specific conditions for the OWTS proposal, in addition to other siting and design criteria.-\ B. Cumulative Impact Issues. The -primary issues.to beaddressed in cumulative impact assessments will normally include he following 1. Groundwater Mounding A rise\in the water table`; referred to as "groundwater mounding ",,m y occur beneath"or clow greent of bWTS as a result of the concentrated or hFgh,,.Vblume of�hyd,raulic loading from one or more systems in a limited area.::: 2. Groundwater Nitrate Lo d ni g Discharges from OWTS contain high concentrations ;ofnitrogen that may contributeto rises in.the nitrate level of local and regional aquifers. For individual cases, the;Director may identify and require analysis of cumulative impact issues other than thosei isted above which, in his/her judgment could pose potential water quali y public hea"'k or safety risks. C. Qualifications. Cumulate a impactassessments required for alternative system proposals shall be p6,�f6rmed by or under the supervision of one of the following licensed professionals: 1. Registered Civil Engineer 2. Registered Environmental Health Specialist 3, Registered Geologist 1 Fol ATTACHMENT E Additionally, the licensed professional assuming responsibility for the cumulative impact assessment should have training and experience in the fields of water quality and hydrology. Cases Requiring Cumulative Impact Assessment. Cases where cumulative impact assessments shall be required are. listed in Table 1. Additionally, the Director reserves the right to require the completion of a cumulative impact assessment in any case Where, in his/her opinion, special circumstances: related to the size, type, or location of the OWTS warrant such analysis. Table 1 Projects Requiring Cumulative !nt* *Note: Director may also require cumulative impact assessment based on project or site. specific conditions. ** The hydrological and water quality analysis requirements may be modified depending on site specific conditions and the extent to which the OWTS discharge contributes flow to catchment area supporting the vernal pool. 2 `esign Nitrate Type. of Geographic Lot Size T`� Groundwater Project Location (acres) Wastewater *_ 'a �' MoundingaAnaI sis Loading Flow'¢gpd) Analysis Individual CountywideNo No Residence Residence Countywide_ - No No with Second ``� Unit San Martin;Area < 5' �`,_w No Yes f' f . - < 1 �` �'r No Yes Y Countywide - #1500+ Yes _ No Multiunit, � � 2;500+ Y t Yes Yes and Non ^ `~ z residential �'> < 5 Yes r San Mar M- r ` - Per Countywide` Yes "` `5+ 1,000+ requirements above {: 2 5+ _ No No Subdivisions -; Countywide)� a <2.5 _ No Any OWTS ` <200 feet 6 Countywide - - Yes** Yes* from a ,° s vernal pool *Note: Director may also require cumulative impact assessment based on project or site. specific conditions. ** The hydrological and water quality analysis requirements may be modified depending on site specific conditions and the extent to which the OWTS discharge contributes flow to catchment area supporting the vernal pool. 2 ATTACHMENT E E. Methods 1. Groundwater Mounding Analysis a. Analysis of groundwater mounding effects shall be conducted using accepted principles of groundwater hydraulics. The specific. methodology shall be described and supported with accompanying literature references, as appropriate. , b. Assumptions and data used for the groundwater mounding analysis shall be stated along with supporting information fA map of the project site showing the location and dimensions of the proposed, ystems) and the location of other nearby OWTS, wells and relevant hydrogeolog c features (e.g., site topography, streams, drainage channels, subsurface drains, etc:)�hall be provided. c. The wastewater flow used for gr"oun dwater.mounding analyses shall be the design sewage flow, unless suppo ted adequately by other do umentation or rationale. d. Groundwater mounding an`alysesrshall be 6s -ed -,to predict the highest rise of the watertable and shall account fo`rkbackground"groundwater conditions during the wet weather -.season. e. All relevant calculatio s necessary for:reviewingthe groundwater mounding analysis�shall accomp, ny the submittal. f AA 777 asures°p op sed t mitigate o\rr reduce the groundwater mounding effects hall be presented and'described as to their documented effectiveness elsewhere; special maintenance or monitoring requirements or -other relevant k \factors. g. For`OWST located:<200 feet and within the catchment area of a vernal pool, an annual water�balance analysis will also ordinarily be required to assess the extent of potential OWTS impacts on vernal pool hydrology. 2. Nitrate Loading a. Analysis of nitrate loading effects shall,: at a minimum, be based: upon construction of an annual chemical -water mass balance. The specific methodology shall be described and supported with accompanied literature references as appropriate. b. Assumptionsand data for the mass balance analysis shall be stated, along with 3 ATTACHMENT E supporting information. Such supporting information should include, at a minimum: (1) climatic data (e.g., precipitation, evapotranspiration rates); (2) groundwater occurrence, depth and flow direction(s); (3) background groundwater quality data, if available; (4) soils conditions and.runoff factors; (5) wastewater characteristics (i.e., flow and nitrogen content); and, (6) other significant nitrogen sources in the impact area (e.g.; livestock, other waste discharges, etc.) ... c. A map of the project siting showing the;location and dimensions of the proposed system(s) and the location of other nearby OWTS wells and relevant hydrogeologic features (e.g., site,to.pography, streams :drainage channels, subsurface drains, etc.) shall be provided. d. The wastewater flow (average) used?fo nitrate loading ana"ly es shall be as follows, unless adequately supported .by otherdocumentation'`or °rationale: L (1) For individual residential systems: 75 god/bedroom; (2) For multi -family residential systems and othernon-residential systems: average morithly�wastewa'ter,flow for the proposed OWTS- e. Mini murn,values used for the total nitrogen concentration of septic tank effluent .,\ k_'A ,.. K - shall be`as follows, uriless supported adequately by other documentation or _rationale: (1) Residential wastewater: 50 mg/ ' (2) No esid`ential wastewater: as determined from. sampling of comparable ';system(s) or from literatu a values. t The. -Director may require the use of more conservative values than cited above if, in`his/her opiiPion, the values are not likely to be representative of the proposed system;(s). f. All relevantcalculationsnecessary for reviewing the nitrate loading analysis shall accompany the submittal. - g. Any measures proposed to mitigate or reduce the nitrate loading effects shall be presented and described as to their documented effectiveness elsewhere, special maintenance or monitoring requirements or -other relevant factors. 4 ATTACHMENT E F. Evaluation Criteria 1. Groundwater Mounding.. The maximum acceptable rise of the water table for short periods of time (e.g., one to two weeks) during the wet weather season, as estimated from groundwater mounding analyses, shall be as follows: a. General Requirement for all OWTS. Groundwater mounding shall not result in more than.a 50 -percent reduction in the required minimum depth to seasonally high groundwater per section B11„67 or B11795, as applicable, for �M. the type of OWTS and site conditions. For -example, where a 3 -foot vertical .- separation to the native groundwater WVOJ required, a short-term "mounding rise of the water table,to within"A5 feet of trench bottom would be acceptable during peak.wet weather conditions. b. Requirement for Large Systems,- Notwithstanding ),above, for all OWTS of 2,500 gpd or more (i.e., "large systems"), the groundwater mounding analysis shall demonstrate that the minimum required groundwater -separation, per :611-67 or B11-95,as applicable, will �be'rnai t ined beneath,tHe system during peak wet Weather.,condition!i , The Director reserves the groundwaterclearance (" protection,of public healt recommendations of`the Criteria for assessing,hvd F -` case_by�case basis: -Th '-.,,',,,-Control Board'�staff or` ,retaining a third party t. `,applicant: <� .,`,,yam 2. Nitrate Loading. Midi from proposed OWTS a. For Areass Serrvi quire,in any individual case, up to 24 inches of coedit ons_) where deemed necessary for h, or basedupon soecif ccrequi'rements or \: applicable California Regio.n'al Water Quality Control Board. r`olb,gical impacts to vernal pools will be considered on a i ctor may�rely,upon rely upon Regional Water Quality d-pa rty<con'sultant to assist in the review. Costs for sultant would be the responsibility of the project m criteria for evaluating the cumulative nitrate loading II be as follows: By Individual Water Wells. (1) Existing Lots of Record: New OWTS on existing lots of record shall not cause the groundwater nitrate -nitrogen concentration to exceed 7.5 mg- N/L at the nearest existing or potential point of groundwater withdrawal (e.g., water well location); and 5 ATTACHMENT E (2) New Subdivisions: The total loading of nitrate from new subdivisions shall not result in an average groundwater nitrate -nitrogen concentration over the geographical extent of the subdivision that exceeds 7.5 mg-N/L. b. For Areas Not Served by Individual Water Wells. (1) Existing Lots of Record: OWTS installed on existing lots of record shall not cause the groundwater nitrate -nitrogen concentration to exceed 10 mg-N/L at the.nearest existing or potential point of groundwater withdrawal (e.g., water well location),, #'' and (2) New Subdivisions. The total loading,of. nitrate from new subdivisions shall not result in an averageegroundwater°nitrate-nitrogen concentration over the geographical extent of'the subdivision�that exceeds 10 mg-N/L. The Director reserves the rightt6fequire, in any individual'case, more stringent nitrate -nitrogen compliance criteriarwhere deemed necesary for protection of public health, or based, ,upon specific'requirerents or recommendations of the applicable California'Regfonal Water Quality -'Control Board. Criteria for assessing nitrate or otherywater qda ity impacts to vernal pools will be considered -on a case -by., -,case basis'., The director may rely upon rely upon Regional. Water Q�ii a,lity Control,Board staffor ard p thiarty consultant to assist in i � .7 "- the re)/iew. Costsofor retaining a thir-`d-party consultant would be the responsiy of the project appka fit. .,� L Santa Clara County Onsite Systems Manual Ge.ne 4 of n �v,n t 1®`h~a,1 0W.1 L ~ 4 Y Requirements Onsite Systems Manual -Part 3 (9/2013) 'Page 1 I - 1. GENERAL REQUIREMENTS A. OWTS SITE PLANS Site plans must include the following information and details: 1. Show all proposed and any existing OWTS drawn accurately to a scale of at least 1 inch = 20 feet. Large parcels must also show the entire site in a larger scale. . P.•y 2. If the slope of the lot is less than 10%, indicate directionjand percent of slope with an arrow. If the slope exceeds 10%, show elevation contour lines at 2 -foot intervals. Note: If a 'grid' dispersal system is proposed, one foot�contou ,•,are required to ensure the dispersal area does not exceed 5%.slope. 3. Note the assessor's parcel number (APN), site.address, County File,Number (if applicable), and any subdivision, tract or,lot�numbers;, 4. Show the -North arrow and scale-., 5. Show the location of all wells, springs, creeks, drainage, swales and/or watercourses on the property or within 100 feet of the p pe?ty,lines. � 6. Show all existing and proposed structures,/driveways culverts, patios,.decks, paved areas, swimming --pools, largoArees, wateraines, etc. 7. Show,all existing and propo�5,'e"d cuts, slopes or embankments over 50% gradient, slides -. and flood plam.boundane5. 8. Include the -name, ad`d,ress, and\telephone number of the legal owner and/or applicant. 9. Show thename Ofadjoining g property owners. 10. Show the property boundaries and their recorded lengths. 11. Show all recorded'easements and right-of-ways and their purpose. 12. Indicate the name of the water company or the domestic water source (individualwell, shared well, mutual water system, etc). 13. Show all existing or proposed OWTS within 100 feet of an;existing or proposed well. 14. Show the location of all components of the OWTS (septic tank, diversion valve, dispersal trenches, etc). Onsite Systems Manual -Part 3 (9./2013) Page 2 B. OWTS INSTALLATION REQUIREMENTS 1. The approved, permitted OWTS site plan (wet -stamped by the Department of Environmental Health) must be available at the job site. 2. Per County Ordinance, the contractor must hold the appropriate contractor's license and be registered with the Department of Environmental Health. 3. The appropriate Environmental Health Office or Specialist must be notified at least 48 - hours prior to starting work. f a.. Main Office (1555 Berger Drive, San Jose) 408-918-3400 b. South County Office (16450 Monterey Road, Morgan Hifl-)' 408-779-0631 (call between 8:00 am and 10:00 am)'' 4. Trenches must not be excavated when th"e soil iswet'r so that the soil,compaction.and/or smearing of the trench walls.occur.. Compaction=andsmearing are problematic in .clay soils and can cause reduce&dispersal field efficiency 5. No part of the septic tank or dispersal field may be co`) red without approval from:the Department of Environmental Health V", Onsite Systems Manual -Part 3 (9/2013) Page 3 C. WASTEWATER FLOWS FOR OWTS DESIGN A. Single Family Residences and Second Units. Wastewater flows used for design of OWTS for single family residences and second:units shall be based on:a:factor of 150 gal/day per bedroom for the first three (3) bedrooms, plus 75 gal/day for each additional bedroom, as indicated in Table 3-1. The design flows for a primary residence and secondary dwelling unit shall be determined independently, regardless of whether the flows are treated separately or combined in a single OWTS. Table 3-1. z Wastewater Design Flows for Single Family Residences and Second Units t Design Flow No` of'Bedrooms (gal%daY) . 150 v 2 300 5.25 5 6 675 _„-,->6 `w,. .� pea. + 75.r bedroom B. Multiunit Residences of OWTS-for,multiunit full consideration of�p guidelines for use m;e 2 the wastewater desi reference +; s-(e.g., US EPA)`fo _ % '; flow; monitoring data for a t adjustment t6the, li wastewater flowtmonitorin' technical information tojsul above, minimum design' -J]6, 6 -'residential Fac'itities. Wastewater flows used for the design ices and'n n -residential projects shall be developed based on I activities occupan y; and facilities. Table 3-2 provides `� .. . ij design wastewater flows. For facilities not listed in Table 3- � shall be estimated based on either: (a) appropriate literature ;he type of facility proposed; or (b) documented wastewater reparable facility. Additionally, the director may consider e4d in Table 3-2 for specific facilities based upon documented Data. In all cases, the design proposal shall include sufficient ort the proposed design flow estimate. Notwithstanding the for any OWTS shall not be less than 150 gpd. Onsite Systems Manual -Part 3 (9/2013) Page 4 Table 3-2. Wastewater Design Flow Guidelines Multiunit and Non-residential Facilities pDesign,'Flow Tye of Business'oriFacility . - (gallons�per day) _ . Assisted living/rest home - per resident bed space 100 - per employee 15 Camps (per person) - day use 10 - overnight use, with flush toilets, no sh:oers 25 - overnight use, with flush toilet and shower"s\ 35 Churches and.assembly halls (per y - without kitchen , fes` ' 5 - with kitchen s -°°, ', . 15 Country clubs, , - per resident member. or caretaker-~ ,,:m,✓' 75 - per guest' ' 25 - per employee ?; 15 Day care :(per patron, employee)`�� , 15 . Detention center - , p7,resident�bed space.. r 100 \� `�', `' -� per employees ._.i 15 Factories and industrial Buildings (toilet wastes only) _� without shlowers (per employee) 15 .with showers (per employee) 35 Motels or -m- otels \,` - . per,guest� 50 - per employee 15 x=i additionahfor restaurant, spa or.other facilities case-by-case Laundromat, with self;service washing machines `N<,,per machine 500 - per customer 50 Mobile home parks (per space) 250 Multiunit residential. housing - apartments, per bedroom 150 - boarding.house and farm labor housing, per bed 50 Offices and stores (per employee) 15 Parks with picnic areas (per person) - with flush toilets 5 - with flush toilets and showers 10 Onsite Systems Manual -Part 3 (9/2013) Page 5 Type of Business or Facih#y Design=Flow ,(gallons pier day) Recreational vehicle parks - without individual sewer hook-ups (per space) 50 - with individual sewer hook-ups (per space) 100 Restaurants and Food Service - - toilet and kitchen wastes (per patron) 10 - kitchen wastes only (per meal served) 5 - additional for bars (per patron) 2 -: per employee 15 Service Station - per vehicle served , - 10 - per employee ,, '°„/ ,: 15 Schools, boarding` 1 y - student andlive-in staff:(per'person)� 75 - daily staff (per person) 15 Schools, day `� r - without cafeteria or showers°(per student),) 15 - with cafeteriaj' r'student) ��.� 20 - with cafeteria and`showers (per student). 25 - staff (per person)\ _ � � a -�, 15 g ls ~, -, Swimming poo a per -patron' 10 peemployee, 15 Theaters��::°ti i per`'seat 5 per employee .� 15 %Wineries'(sanitary w'as eonly) w tasting, \oom,�per visitor 2.5. per employee`;` 15 special events case-by-case C. Flow Equalization. Flow equalization may be used.for non-residential and mixed use facilities that experience significant, regular and predictable fluctuations in wastewater flows. Examples of applicable facilities include, but are not limited to: i Churches • Schools ® Special event venues Onsite Systems Manual -Part 3 (9/2013) Page 6 Flow.equalization is the process of controlling the rate of wastewater flow through an OWTS by providing surge capacity storage and timed -dosing of the incoming flow. Installed following the septic tank, it allows peak surges in wastewater flow (e.g., from a weekend event) to be temporarily stored and metered into.the treatment system and/or dispersal field at a relatively even ("average") rate over an extended number of days (e.g., during the subsequent week). This generally aids OWTS performance. Where flow equalization is.proposed to be incorporated in an OWTS the following apply: 1. the septic tank capacity shall be sized based on the peak daily flow for the facility; 2. the design flow used for sizing supplemental treatmen'tunit(s) and/or the dispersal field may be based on the equalized ("average") flow. rate. rather1than the peak daily flow rate for the facility; 3. engineering calculations and specifications must be submitted substantiating the proposed design and operation of the flow equalizati6n,system; and 4. an operating permit (per e secti 11-92) will be req Onsite Systems Manual -Part 3 (9/2013) Page 7 2. CONVENTIONAL OWTS REQUIREMENTS A. DESCRIPTION Per Santa Clara County OWTS Ordinance, a "Conventional OWTS" means a type of OWTS consisting of a septic tank for primary treatment of sewage followed by a system of drainfield trenches for subsurface dispersal of effluent into the soil. A conventional OWTS may utilize gravity flow or a pump system to convey effluent from the septic tank to the drainfield. B. SITING CRITERIA The following minimum siting criteria must be met o approval of...any conventional OMITS: 1. Soil Depth. Minimum.depth of permeable,soil beneath the bottom:of the proposed v dispersal field shall be 5 feet. Permeable bikis defined,as having a�percolation rate of 120 minutes: per inch or faster or having a clay content of less than 66.percent, and shall not include rock formations,that'contain continuous,channels, cracks or`fr'actures. 2. Soil Fill. Maximum depth of soil ;fill covering any porfiion,of the area proposed for installation of a dispersal system shall noftxceed twelve inches.in depth. 3. Vertical Groundwater Separation. Mi\ atnimum4equired vertical separation distance between trench bottom and`groundweter shall be determined according to the soil percolation rate ais-follows; 1 " N Anr "` PeGcolation Rate* Vertical,Distance av Less thanI. , , ' Not Permitted � 1-5 `\ '�� `� 20 6-30 `,: 8 31-120 Mor`ethan 120",Y Not Permitted *averag&.,;.�` 4. Areas of Flooding. OWTS shall not be located in areas subject to flooding as defined by the limits of the 10 -yr floodplain, determined or estimated from published floodplain maps or on the basis of historical evidence acceptable to the director. New OWTS that are to be located in areas of special flood hazard, as identified in division C12 of the County Code, must comply with all: relevant provisions of division C12. 5. Ground Slope. Maximum ground slope in the dispersal field area shall not exceed thirty percent. Additionally, for any site where the ground slope exceeds twenty percent, Onsite Systems Manual -Part 3 (9/2013) -Page 8 approval shall be dependent upon completion of a geotechnical report. as provided in Ordinance section B11-83. See Part 2 of this Manual for geotechnical report requirements. 6. Horizontal Setbacks. Minimum horizontal setback distances from various site features to OWTS components shall be as listed in Table 3-3: Table 3-3. Minimum Horizontal Setback Distances 1 For areas tributary to and upstream of water supply intake; setback distance measured from high water mark. Exceptions allowed per SWRCB OWTS Policy, as follows: (a) for replacement OWTS, comply to the maximum extent practicable and incorporate supplemental treatment unless director finds no impact or significant threat to water source; (b) for new. OWTS on pre- existing lot of record (pre=May 2013), comply to maximum extent practicable and incorporate Onsite Systems Manual -Part 3 (9/2013) Page 9 Minimum Setback Distance (feet) Site Feature To To `: ,Dispersal Field Septic Tank rit`, All wells and spngs .. 100 100 t r Public water supply wells, 150`, 150 Watercourses ~\� 0 General (from top of bank) ``, .'r 100 100 • Between 1,200 to 2,500-feet`from a public`Water, 200 = 100 system intake' . Within 1,200 feet from a public'water-system 400 100 intake': Reservoirs (from highwater mark) `•, � ' ; � �� \' "' 200 General, IN ��` a Within i 200 from 200 400 400 �, eet .,a public watd'r'supply VI,= intake' <' \.. ! nK. Cuts orsteep embankments.(from-top\ f cut'�, 23 4 X h 10 feet Steep slopes-(frohbreak of sl pe)° s\ ? '.. 4 X h23 10 feet Unstable land mass" ti� ' 100 100 Drain .geway/drainage'Swale (from.ed'ge of flow path) 50 50 Foundation. 10 5 Property line ,rj 10 10 Septic tanks �;�'� 6 N/A Swimming pool. 25 25. Road easement, pavement, or driveway 5 5 1 For areas tributary to and upstream of water supply intake; setback distance measured from high water mark. Exceptions allowed per SWRCB OWTS Policy, as follows: (a) for replacement OWTS, comply to the maximum extent practicable and incorporate supplemental treatment unless director finds no impact or significant threat to water source; (b) for new. OWTS on pre- existing lot of record (pre=May 2013), comply to maximum extent practicable and incorporate Onsite Systems Manual -Part 3 (9/2013) Page 9 .BASED ON;PERC01:ATION RATE supplemental treatment for pathogens per sections 10.8 and 10.10 of SWRCB OWTS Policy as detailed in the .Onsite Systems Manual. z h equals the height of cut or embankment, in feet. The required setback distance shall not be less than twenty five feet nor more than one hundred feet. 3 Setback distance may be reduced in accordance with recommendations provided in a geotechnical report prepared by a civil. engineer or professional geologist consistent with section B11-83 and guidelines contained in the Onsite Systems Manua/. 4 Steep slope is considered to be land with a slope of >50%and distinctly steeper (at least 20% V. steeper) than the slope of the adjacent tank or dispersa,Hield;area. 7. Soil Percolation Rate. The average soil percolation'r`ate in the proposed dispersal field area shall not be faster than one minute per'inchF(1 rn i nor slower than one hundred twenty minutes per inch (120 mpi), deter'mr ed in accordance with procedures prescribed by the director in Part 2 of,'this Manual. 8. Location and Accessibility. OWTS shall be situ's ed on the'same propertyas the building(s) being served and shall be located to be easily accessible for maintenance andl,Tpairs. C. SEPTIC TANK REQ/U�Ie-R.�E+IVIENTS 1. Minimum Capacity._.Septic tanks must have -4 min m'um capacity of fifteen hundred (1,500) gallons or twice thb,peak daily *wa`stewater flow or the facility served, whichever is greater..; 2. Two Compartments. Sept c'tariks must be.oftwo-compartment construction, with the first compartment equal to' wo`-thirds the total tank volume. The compartments must tie se a arated�b~ L k p y, baffle`o:requivalent-arrangement. 3. Materials. Septic tanks:musfbe. watertight, properly vented and constructed of reinforced concrete, heav\yweightreinfo rced concrete blocks, fiberglass or other durable,.,non-corrodiblematerials as approved by the director. Septic tanks shall be designed to,,mithstand any anticipated weight placed above it. All septic tanks shall be listed and approved by IAP.MO or an ANSI accredited testing organization: exception to this requiremen`t,ma:be granted where structural design calculations for the septic tank are provided by a California registered civil engineer. 4. Access Openings. Access to each septic tank compartment must be provided by a manhole opening at least twenty inches in diameter. 5. Access Risers. A riser must extend from each manhole opening to or. above the surface of the ground.. The riser must be of a size larger than the manhole opening, be both gas - and water -tight, be constructed of durable material and equipped with a secure cover. 6. Effluent Filter. The outlet of the septic tank shall be fitted with an effluent filter capable of screening solids in excess three -sixteenths (3/16) of an inch in diameter and Onsite Systems Manual -Part 3 (9/2013) Page 10 p, W�;TERTIGHTACCIwSS R. ISER SECURE. GAS TIGHT'IRON OR AP�'RED:CUAAL.{TP)' MAHOIE AR3FAEY XiSTIVG: OU GRADE' I n MIN. N-1 GROUT. SANI IARYTEE. QR Ef f LUCNT FILTER . FLEXIBLE CQUPLING ♦: jos ♦ o". = a ..ate.,.. Q It . WITH .S:S. CLAMPS _ " , '24iVENT V�lhTCRTIGHT SE'4L & INET FLC1W LINE TO CJESPOSAL +r tai�'�jsq-iio�P..i —r��R "p Qu 'u� ViViWCtnv: i SEAh1NITH:- t-iYpRAULIC WATER r SCUtirS: STOP -;OR THOROUGH LAYER OUTLET uT° .- . a" AR E:: tNLEi' C MPAR*lTMENT a PIPE 2f3;SEPTfCTANK CAPACfTY' .SANITARY. 7"AT SOt.IDS i AGGUiv1ULATION , d 1..PRF---CAST CONCRET- E: 'F ---S DTIC 'I"ANI< � 0Cl7'C:�7CO11,�fP'ME'NT,•, T1aA 'KCAPACI�Y / ti} V' 1. " 4, a/`•.r•\/ ! P -:.,�\ ,/..f'a.�r ,/'a �'+ a \/v%Y,,/. 'ti' !'\,t°�f`* � J. `-�\ j - \ , 3 G.OMPACTED�;BEDD.ING; .b§ E,..._ - . ,- c - SECTION ' fICUf�E. a conforming to NSF/ANSI Standard 46 or as otherwise approved by the director. 7. Tank Connections. All connections from building to septic tank must conform to construction standards as required by the County building official. D. PIPE REQUIREMENTS 1. Solid pipe, joints and connections. Solid (non -perforated) pipe for OWTS must conform to the standards of the most recent edition of the Uniform Plumbing Code, which is adopted by reference into the county's building ordinances. Pipe diameter must be four inches. All solid pipe joints and connections must berglued, cemented or made with an elastomeric seal so as to be watertight. X_ 2. Distribution pipe. Perforated pipe for conventional OWTS dispersal systems must conform to the most recent edition.of the Uniform Plumbi"hg Code, which is adopted by reference into the county's building ordina ces. The pipe diameter\must be four inches. E. DISPERSAL SYSTEM REQUIREMENTS 1. Trench Specifications. A conventiona1s.ubsurface°dispersal system must consist.of a series of trenches meeting thespecificat of ns in Table�3 4.. ;Table 3-4. Conv ration al OWTS DispersalTT ench Design Parameter-_' w„ Tom' Requirement Determined based on design flow and Trench-Nnigth, \�� percolation rate; see below r4�`"v.`"�, `: Recommended maximum of 100' per trench Trench width 18 inches minimum; 36 inches maximum Trer Depth <. 3 feet minimum; 8 feet maximum Minimum cover over rock; in inches* 12inches f __J Depth of rock u d'er pip[�(minimum) * 12 inches Depth of rock over pip (minimum)* 2 inches Size of rock * % to 2%: inches 2 times the depth of rock below pipe; Spacing of trenches, center to center, in 6 feet minimum, plus 1 -foot additional spacing feet, minimum for every 5% increase in dispersal area ground slope above 20% Onsite Systems Manual -Part 3 (9/2013) Page 11 1:164:106 i'm SANITARY TEE END VIEW TYPICAL LEACHING TRENCH FIGURE 3 INSPECTION WELL FILTER FABRIC //j NATIVE TOPSOIL �� BACK FILL o - - -- - - -0 -� 0 O 000° . 00 °°'no�O Qap00 °o�O DpO° 0��- Oj0o00 00 w00W p'.doo°800 o p° °°ogo o PIPE g 0 o °8DRAIN .. p .(2 o�o g o 00 0 O ° o 0 0 ° g 00 ° O . �Qp 0°O°�0p DRAIN ROCK SIDE VIEW UTILITY BOX NATIVE TOPSOIL BACKFILL FINISHED GRADE 1:164:106 i'm SANITARY TEE END VIEW TYPICAL LEACHING TRENCH FIGURE 3 2. 3. * Other materials may be substituted for drainrock in the dispersal trenches if it is determined by the director that the material will serve the same function as drainrock as follows: 1).support the trench sidewalls and maintain the integrity of the infiltrative, surface: and 2) provide adequate storage for septic tank effluent surges. The maximum depth and spacing. between trenches may not be modified. Materials approved:as drainrock substitutes must provide equivalent effective infiltrative surface consistent with trench sizing requirements per paragraph E3 below. Reduction in trench sizing: requirements, up to 30%, may be approved by the director for IAPMO-certified dispersal systems. Trench Construction. a. Trenches must be placed in undisturbed earth, in ari accessible area, and shall not be covered by paving or other impermeable or compacted surface. b. The bottom of a trench must be level, 100 lineal feet of trench; trenches sha contours to the greatest extent practi c. Adjacent trenches on slopes must`be ("relief line") in a manner that allows` the depth of the rock before the sewa :ha.variation of no more than 2 inches per e aligned par, NZ to the ground surface I'e. nected with a watertight overflow line h trench4on be filled with �sewage effluent to Flowsto.the:next lower trench. d.. Trenches must not be excava#edwhen the.soil is,so wet that smearing or compaction occurs. e. In clay soils.when_glazing occurs,\the trench-surface5,must be scarified to the depth of the glazing and the,loose material rem. ovecl. L Rock ma erialin the tr n`ch must be washed and�free of fines, and must be covered with an approved filter.fabric silt barrier (geotextile) prior to backfilling with natural earth g�capp'ed_irispection user shall be,installed-within each trench to.provide a means of ,observing the effluent,level, in the trench. h Erosion control measures shall�be implemented following installation per X requirements of Section 1311-83�c) for any conventional dispersal system where: (1) ground slope excee&20%; (2) above -grade cover fill is added; (3) design flow exceed's,-1000 gpd; or (4) a grading and/or drainage permit is required for project site development,per.Division C12, Chapter III of the County Code. The plan submittal for the 011' TS shall include an erosion control plan in accordance with requirements of rdinance section 1311-83(c). Trench Sizing. a. Design Flow. Design wastewater flow used for determining the required square footage and length of dispersal trench shall be determined in accordance with the criteria in Part 3-1C of this Manual. b. Wastewater Application Rates. The wastewater application rate(s) used for determining the required infiltrative surface area and overall trench length shall be Onsite Systems Manual -Part 3 (9/2013) Page 12 based upon representative percolation test results for the soil zone corresponding with trench bottom depth, and: the criteria in Table 3-5. Table 3-5 Wastewater Application Rates for Conventional Dispersal Trench Sizing" Percolaffon.Rate Wastewater Apphcation'Rate` (MPI) (gpd/ftZ): -. 1-5 .\:.. 1.2 10`-0.80 24 '': 0.60 30,: �. 0.56 45 ""0..45 60 ' y'0.35, 90 91-120 0 20 "Interpolate between reference valuesfor"othe'r,;percolation rates; see\ attached table for expanded -listing of interpolated polated values. c. Effective Infiltrative Area. VA 1) Standard Requirement. For\trench sizing;,the�',effective infiltrative area shall be limited to four�(4`)�square fee`per lineal footof trench length, which may include"any"Co mbin. 'ion of trench `bottom area and trench sidewall area below the invert of the perforated distribution pipe. For example, this may be p ised of:,(a) 15'ft widebottom a fea plus two sidewalls of 1.25 feet each; (b) 2=ft wide bottom area plustw` dewalls of 1 foot each; and so on. 2) Deep Trench" Exception: Under certain (favorable) soil and site conditions.where \�\ deep er dispersal,trenchh (e.g•., up to 8 -feet deep) construction is acceptable, the * effective infiltrative surface'may be increased up to a maximum of eight (8) square feet per lineal foot. This exception is applicable to individual residential OWTS�where the'dispersal site meets all conventional OWTS siting criteria, and further limited.WA tes where: (a) ground slope is <20%; and (b) soil percolation rate is in tfie.,range of 5 to 60 mpi. d. Trench Length Calculation. Required trench length for 100% capacity dispersal field shall be calculated as follows: Trench Length, L = Q / (R*A) Where: Q = Design wastewater flow, gpd. Onsite Systems Manual -Part 3 (9/2013) Page 13 R = Wastewater application rate, in gpd/ft2 A = Total infiltrative area per lineal foot of trench, in. ft2 (4 feet standard) e. Dual System Requirement. Total dispersal trench capacity shall be provided for (2) 100% fields (primary and secondary) each sized per (d) above. Both primary and secondary fields shall be installed, and shall be equipped with an approved (manual) diversion device to allow alternating use of the two fields,, typically switching between fields every.6 to 12 months. Onsite Systems Manual -Part 3 (9/2013) Page 14 - - Table 1. Standard Wastewater Application Rates - Septic Tank Effluent Percolation Rate= Application Rate t.. "'(MPI) = u Percolation Rate' Application Rate ; s.(gpolft') Ito 5 1.20 51 0.41 6 f1 12 .52.: '0:40', 7 1.04 53: 0.40 g 0.96 54 9 0.88 55 0.38 11 0.78 57, 0.37 12 '0 77 y 58 13 0.75 59 0.36 J e14 - 0 74 ' { 60 ,. 0.35;<, 15 0.72 61. 0.35 16 : 0-70" 62' 0."$ 17 0.68 63 0.34 -"10'67 j .:......:, 64 == ; 0 34x. 19 0.65 65 0.33.: 20 0 64 66: ° 0.33-'- .21 0.63 67 0.33 22 0.62. .. a 6$ 23 0.61 69 : 0.32 . 32, 25. 0.59 71 0.31 26. 0 59 „ .... ,a...72.::: 27 0.58 73 . 0.31 0:5,7 74 0.30;_ 29 0.57 75 0.30 0.30`: _ 31 0.55 77 0.29 4 0'55 78 0:29 33 0.54 79 0.29 0.53- . _ .. ;; 80 35 0.52 81 0.28 36 0 52 82-: } 0:28`:"} 37 0.51 83. 0.27 0,.27::: 39 0.49 85 0.27 0.26 41 0.48 87 0.26 42_....' - _. OR , ` ., .: 88.. -_ ^ • k . 0.26 j _ 43 0.46' 89 0.25 0' 46 90: 45 0.45 91-120 0.20 :: 46 " 47 0.44 49 0.43 50 SeMce Opening tis ,Inlet : - _ S¢u Layer �ia':� ■eta ..702-0 an .e sit.■®.a■ �r Water Level Sludge: Effluent Find& required at outik- Cement/concrete tanks must -be, Lt ed whenever possible: Alternative materials, are approved on a':site specM -''b"' . hM epartrnent of. Environmental Health maintaihsa list ofapproved sept"ic- tanks: Septic tanks must be a °minirrim of 1S00;ga1{oris with two compartments: The frst compartment must: be two=thlyds:.the'total tank volume. The: cornpattments must b,e. separated Eby a baffle or.egtiivalent arrangement: Septic tanks'mustI be.waterti6ht acid constructed of reinforced concrete; hea, yweight reinforced :concrete blocks,, or'othef li-material5 approved by DEH. Access to each septic tank compartment must be:provided tiy;a manhole at; least 20 inches tn)dlarneter and having a ,durable handle to facilitate: removal_.: A rl§er.must extertd.from eacki.manhole cover to -or above the surface of_the ground The reser must, be of a siie:,larger;•than-the: manhole-coVef.,-be:li'oth gas and:water-t gh_k,.'and. be constructed of:durable rnat&iAL. r 03%0110:. �z :Septic Tank;, Two drainfields, each TDD�lo othe total size: required, shall be,, lhppl!O- n fntercorinected:wrth_an:approved diversion:salve , The Va[Vejhust be capable -of directing"th _bc, efflueht�tb... bh6cJr-aihfle k�-b` these -tank,` Id time'. Drainihe pipes ,s atf�be�6f-apprpypd,,pgr'For�t perforated least hthe §*ih: diameter:, The tightline from tion Valve must beABS or PAP PVC-Joln schedUl o"i OlLfe,....,cemen t' i or -'-el attdmetflcsea, The .dra6llhe-trench ,:b Pttom; m ust be' evel. The ,trpp chos -MUtt:lbeadeast, 18: 166he-sj-wide . and t9:8feef. deep. 1 A :ihchd§'6f died 6,W69"d dr&n-ro6k M'Ust`bep aI- beneath. ced,behea ' drainpipe-and.fiaround ;jnd:xW lfte',pjpe-.at east-2:Jhches.. .-The- draln-ti-pck must-be;covered-: with :fi ter fabrlct6 pr-eve'n;-t'z:'log' ' 9,ng.. !�,r _�,w t -,pn or,to backrulih 9- Oip-14-9 13 DRAINF,IELD"SY STEMOWILEVEL� LAN S 5% SLOB); on center minimum, Av GrW',,S.y9tem:,0 r jLdaicft ds" minimum: pip brQ49IOUt.thL"'gi& -6=fttcredit f6eejds'6f Vzitut6l terfa1h::fn'U!kb"e- 5% br'Jes,-, -To, :,ensure eVent,,Id istri b qVi ont - hrcOghout-the ' `'OHOI the b6tt6fli of 11 :trenches:mustbel' el Dralhllhbs must be 0-foet"ili" ehg!;h'- inlmume ,100.9 n Length 'MUirriurh Oran mid SwAcim 6h Hill#i4j$i- 91 Ir PIQ pjng,,.,and 03/02/10 -15 3. SITE AND DESIGN MODIFICATIONS A. COVER FILL SYSTEMS 1. DESCRIPTION The. term "cover fill' refers to a dispersal trench system where the trenches are excavated entirely below grade, but up to 12 inches of soil fill is placedon top of native grade to provide the required backfill cover over'the pipe and drain rock. The wastewater is dispersed into the native soils, not into the fill soil;`The"p pose is to allow for shallower trench depths where necessary or desirable to.meet'soil ddpthand groundwater separation requirements. It provides for improved use,of the absorption capacity of the near surface soils, which tend to be most permeable and most effective for absorption and treatment of wastewater effluent. This is a design modification for use with a conventional dispersal trench system. Cover fill also be used in conjunction with certain alte native dispersal systems (shallow pressure distrib"ution, pressure=dosdd'sa d trench, and drip%dispersal) presented in Part 4 of this Manual 2. SITING CRITERIA a. Setbacks. All horizont etback siti g,criteria applicable to -conventional OWTS as specified in Ordinance section 611-67 raid -Part 3-213`of pis Manual shall apply to OWTS i tF.A � Y where cover fill,is used. Required setbackdistances for dispersal trenches shall be measured from the edge,of.trench, not from the edge of the installed cover fill. b. Soil Depth; Groundwater` Separation and,Percolation. Soil depth, groundwater .,separation and`percolation;ihall conform,W the requirements applicable to the type and de gn of the dispersaksystem proposed. c. Ground Slope. Maximurri�allowab a ground slope for cover fill systems shall be 20%. 3. DESIGN AND CONTRUCTION REQUIREMENTS 1. Dispersal Trenches.\ -The drain rock and perforated pipe sections shall be installed entirely within native soil, and all other aspects of the dispersal trench design shall be in conformance with requirements for conventional dispersal fields, as specified in Part 3-2 of this Manual or, in the case of an alternative dispersal system, in accordance with requirements for the particular type of system (e.g., shallow pressure distribution trench, drip dispersal, etc) and detailed in Part 4 of this Manual. Onsite Systems Manual -Part 3 (9/2013) Page 15 2. Site Preparation. Prior to placement of fill material, all vegetation shall be removed and the ground surface ripped or ploughed to a depth approximately 6 to 10 inches to permit good mixing of native soil and fill material. 3. Fill Material. The soil used for fill shall be similar in texture to the native surface soil in the dispersal field area. Sand, gravel or rock do not qualify as acceptable material for cover fill. Particle size analysis (hydrometer method) of the dispersal site soils and fill soil shall be required for DEH review and acceptance of the proposed fill soil, except in cases where -the fill is obtained from similar soils at theSroiect site. 4. Sequencing. The fill shall be placed prior to dispe`rsal)jt'rench excavation and installation of dispersal piping and appurtenances..,, S. Areal Coverage. The fill shall be continuqus and constructedsto,provide a uniform soil cover of at least 12 inches over the dispersal trenches. The fill shall. extend a minimum distance of 15 feet from the edge of trench`in the down-slope direction and 10 feet in the upslope and side -slope Orections. Ona 1 vel sitedthe fill shall extend a minimum of 10 feet in all directions. The�toe_of�,the fill shall`be tapered at no less than a 3:1 grade, beginning at the above required I!foot-or 10 -foot distance, as applicable. Where the N primary and secondary dispersal=fields are,adjacent to one,another, the cover fill should be continuous over.both-fields. 6. Fill Comoaction:-Fill shall be`placed ins layers "lifts") of Piot more than six (6) inches and compacted to comp c on pr j imu ante With ;re( J civil engine lyrthe same drydensity as the native soil. Normal achieve this requirement shall consist of track -rolling each Alternative"compaction procedures may be'allowed by DEH z.� endations and supporting technical data supplied by a. 7. Revegetation and Erosion Control. Following system installation, measures shall be l taken to revegetate theJsoilfill and adjacent disturbed areas, and to apply othererosion control measures as`needed, such as straw mulch, silt fencing, straw wattles, and hay bales. The plan submittal for the OWTS shall include an erosion control plan in accordance with requirements of Ordinance section 611-83(c). Onsite Systems Manual -Part 3 (9/2013) Page 16 10' MIN. (UPSLOPE AND SIDESLOPE DIRECTIONS) 3 V 1�- ORIGINAL GRADE; STRIP VEGETATION AND PLOUGH OR RIP PRIOR TO PLACEMENT OF SOIL COVER FILL DISPOSAL TRENCHES; INSTALL FOLLOWING FILL PLACEMENT REVEGETATE SOIL FILL W/ GRASSES OR OTHER GROUND COVER FOLLOWING PLACEMENT AND COMPACTION SOIL COVER FILL; SIMILAR TO NATIVE SOIL TEXTURE; PLACE AND COMPACT IN.LIFTS OF 6".OR LESS; COMPACT BY TRACK -ROLLING, TWO (2)' PASSES MIN. 15' MIN. (DOWNSLOPE DIRECTION) NATIVE GROUND SLOPE, 20% MAX. APPLY EROSION CONTROL MEASURES, SUCH AS STRAW WATTLES, AS NEEDED 1 COVER FILL SYSTEM FIGURE CROSS-SECTION 4 B. CURTAIN DRAINS 1. BACKGROUND Controlling surface water and shallow perched groundwater may be an essential part of protecting the integrity and performance of.OWTS dispersal fields in certain situations. A particular situation of concern is in areas where rainfall readilypercolates through very permeable surface soils and perches along the contact with the less permeable substrata. Dispersal trenches can act as a collection area for this transient subsurface water flow, and in the worst case. may be flooded during. heavy rain events=b7•,throughout the rainy season. This reduces the dispersal capacity during the wet season ;;and it can also contribute to a long-term decline in the dispersal system effectiveness and potential surface failures'. One of the most effective drainage measures is a curtain'drbin. \ (also called subdrain or french drain ),which consists of a gravel filled trench installed uphill of a drainfield system, designed to intercept shallow perclfed groundwater flow and divert it away from or around the dispersal field. le' 2. SITING CRITERIA a. Setbacks. Santa Clara County Codb does not contain explicit regulationsor specifications for the use or design of curtain drains.\ Howe~ver, based `on criteria contained in the RWQCB Basin Plans and requirements follow`ed.in other counties in the\S.F. Bay Area the following horizontal setbacks'shall.applyto curtaindrains'�. Horizontal Setbacks Reauirements for Curtain Drains * measured from edge -'of dispersaktrench to edge of curtain drain trench (perforated pipe section) b. Site Investigation. Prior `to approval of a curtain drain installation, a site investigation shall be conducted to: (1) document the presence or strong probability of groundwater perching on.bedrock or a clearly definable restrictive/impermeable soil layer; and (2) determine appropriate depth and location for curtain drain and outlet point, based on soil, groundwater, and othersite conditions. Onsite Systems Manual -Part 3 (9/2013) Page 17 Reference'Location, Y Horizontal Setback Distance* ,'Uphill ofthe,dispersal field.' ; �� *' �' 15 6ateral of the dis' p.ersal field ,(a`to.ng slope contour) 25 . Downhill of the dispersal field',`.. 50 * measured from edge -'of dispersaktrench to edge of curtain drain trench (perforated pipe section) b. Site Investigation. Prior `to approval of a curtain drain installation, a site investigation shall be conducted to: (1) document the presence or strong probability of groundwater perching on.bedrock or a clearly definable restrictive/impermeable soil layer; and (2) determine appropriate depth and location for curtain drain and outlet point, based on soil, groundwater, and othersite conditions. Onsite Systems Manual -Part 3 (9/2013) Page 17 3. DESIGN AND CONSTRUCTION REQUIREMENTS A curtain drain shall consist of a gravel -filled trench constructed as shown in the attached schematic diagram and designed in accordance with the following specifications: a. Trench Width: 12 inches minimum. b. Trench Depth: Shall extend to a depth of at least 6 inches into the underlying impermeablelayer. C. Filter/Backfill Material: Filter material shall be elean;'durable 3/4 to 1% -inch drain rock, extending from trench bottom to within 6 to 12 nclh` s oftgrade; backfill to grade with 5.tif ; native soil.! d. Filter Fabric: A geotextile "filter fabek','-envelope shall surround\the;drain rock. e. Perforated Collection Pipe: Collection pipallconsis�of 4 -inch diameter perforated drain pipe, oriented with holes down and instalie.lob top- of the drain rock, approximately 2 to 4 inches above trench bottom f. Outlet Pipe: The outlet pipe shall cons si t'ofminimum 4 inch diameter solid (norr- per forated) dram pipe` g. Cleanouts. Provide clean6ds to grade,:. _'(6)' at the ups op end of the drain; (b) at bends of 450 or greate ;}aod (c) at� least every 4001'feet along the length of the drain. h.. Slope:-Tch and pipe sh be=sloped for'gravity flow at a minimum 1% gradient throughout the trench ank.'&ending tort}' a outlet point. L Outlet Protection. Protect downslope outlet against blockage or damage through the use of screeninr,g, rock cover, junction box or other suitable means. 12 ..� . j. Erosion Control; Provide Jrosion protection at drain outlet point. * Onsite Systems Manual -Part 3 (9/2013) Page 18 SURFACE DIVERSION DITCH GRANULAR SLOP PROTECTION; 4" RIPRAP NATIVE TOP SOIL BACKFILL;. MOUND 6" TO 8" TO FORM CONTINUOUS DRAINAGE BERM, NON -PERFORATE DRAINPIPE CROSS SECTION OUTLET DETAIL FILTER FABRIC; MIRADRAIN ;�v" 12" OR APPROVED EQUAL v DRAINFIELD TRENCH >o� o� 3/a" - 1YZ" DRAIN ROCK?o°g° B° oo c °p° ° oo ° ° 0 0geo 00 o ° 0 0°8 0q, 3� o 0. ° o ° � oOd o� o ° °.° °° ° °°d° ° ° o °° 0 o°o°o°c� 6" MIN. 3" OR 4" PERFORATED 12 \ PLASTIC DRAINPIPE; LAY INVERT ON DRAIN ROCK; 2" 15 MIN. �— ABOVE TRENCH BOTTOM`�`�� \\ CROSS SECTION IMPERMEABLE LAYER CURTAIN DRAIN SCHEMATIC DETAIL C. PUMP SYSTEMS The pump systems used in the connection with either conventional or alternative OWTS shall be: (a) appropriate for sewage applications; (b) of the size and type to meet the hydraulic design requirements; and (c) designed and constructed in accordance with attached pump:system design requirements. Z- � t t I Onsite Systems Manual -Part 3 (9/2013) Page 19 EFFLUENT PUMPING SYSTEMS DESIGN GUIDELINES General Requirements Effluent pump systems may be considered. when they offer a better alternative for the protection of public health and safety or the only safe opportunity for parcel .development. Due to the problems inherent in mechanical devices, pump systems are to be considered only after gravity feed options have been explored and shown to be infeasible. Design Requirements Drainlines must meet all requirements as set forth in the sewage ordinance. Both primary and secondary fields must be fed by the pump. The system must be designed by a qualified state Registered Civil Engineer or Registered Environmental Health Specialist. Upon installation the designer must inspect and test the pump system- in the presences of the Department's -Environmental Health Specialist. Upon completion the designer must submit a written statement to the Department of Environmental Health certifying that the system has been installed and operates according to the design criteria. The Department's Environmental Health Specialist will sign the final occupancy section of the building permit only upon satisfactory final inspection of the pump system and receipt of the designer's statement of final inspection. Float switches must be used and installed such that the float switches -or wires do not become entangled. Clamps must be of non -corrosive material. A Check valve is required at the pump. Reauired Materials and Details Provide specification sheets for the pump tank, tank risers, and pump, including the pump performance curve. State the elevation of the pump and drainfield pipe at the highest elevation. Show the calculations for total dynamic head through the effluent piping and valve on the Pump System Work Sheet provided by this department. Provide specification sheets and show the placement of float switches indicating the 1 Y2 days storage capacity, audio/visual alarms and any other materials proposed for use. Sizing Criteria Septic Tank Septic tank must be sized as required for the projected wastewater load. A pump system does not require the use of different sizing methodologies. Updated 10/12/04 Pump Tank The pump tank must have sufficient capacity to hold the following: the dosing volume 1'/2 days storage capacity above the "on" switch pump displacement volume �• sufficient distance from the tank bottom to pump inlet to allow space for any solids to settle without. interfering with the pump operation As a general rule, the pump tank volume will be the same as the septic tank volume. See Diagrams 1 and. 2, Pump Sizing The proposed pump -must be able to provide the required gpm at the designed head. See Pump System Work Sheet and friction loss tables provided by this Department. DEFINITIONS Dose Volume: Pump.on to pump off. The amount of wastewater pumped in one cycle. High Water Alarm: Float set 2 inches above pump.on alerts user of pump failure, both audio and visual alarms. Pump On:: Float set to .turn pump on. Pump Off: Float set to turn pump off. Lowest water level in pump tank. Pump Tank:, A septic tank without a mid -tank baffle. Use this figure to calculate the appropriate: setting for pump switches and alarms. Storage Capacity: Volume of the pump tank from high water alarm to tank outlet invert. Total Dynamic Head: A combination of: 1. the difference in elevation from pump `off'to pipe invert at the beginning_of the highest drainfield. 2: and the .friction loss of delivery pipe and fittings. . Updated 10/12/04 2 To Coard,1. Paile�j To Dra ofiel.,d tank:1% utcly l] �. ..' O Dosing Volume }. ! '1i;,. 411 ep i' licit#utn o:l't Kik Diagram 1 TO Gone '61 Panel + Yo:" Dra nfiold Fro t•5epk�c� lw. 4 . tank, ----$— ° 'l '' Ovs Storni-ye - f Dosing Valume - j :� 4T,F Diagram 2 Updated 10/12/04 3 PUMP SYSTEM WORKSHEET Applicant Date Owner File No. Site Address City APN Designer (RENS or RCE). Number of bedrooms Total square footage of living space Septic tank size Installed drainfield Expansion drainfield Elevation of highest drainfield (ft) Elevation of pump off (ft) Total lift (Ft Head), _ (A) TIGHT LINE Diameter of tight line (inches) Length of tight line from pump to upper drainfield (ft) (B) 21211II[ ;CR CALCULATIONS: Friction Loss in Pipes and Fittinas: (D/100 ft) x (friction loss per chart) _ (E) Head in Feet Required Pump Size: (A) + (E) _ (F) Total Pumping Head in Feet Pump Size: (F) versus GPM = Pump Size (refer to pump curve) Pump Model:. (Attach Pump Curve) GPM at (G) (ft of head: from pump curve) Manufacturer/Model Reauired Capacity in Gallons Dosing Volume Storage Capacity (1 % days) Pump Displacement Volume from tank bottle to pump base Total tank capacity Pump Tank Information Manufacturer Updated 10/12/04 Size Gallons per inch 4 Pipe Length Total Pipe No. of Fittings Equivalent (ft) Equivalent (ft) See chart 900 standard elbow X = standard elbow X _ _450 _900 long radius elbow X _ _other fittings X = _gate valve (fully open) . X = check valve x = (conventional swing) TOTAL= (C) Total Length of Pipe = B + C = (D) CALCULATIONS: Friction Loss in Pipes and Fittinas: (D/100 ft) x (friction loss per chart) _ (E) Head in Feet Required Pump Size: (A) + (E) _ (F) Total Pumping Head in Feet Pump Size: (F) versus GPM = Pump Size (refer to pump curve) Pump Model:. (Attach Pump Curve) GPM at (G) (ft of head: from pump curve) Manufacturer/Model Reauired Capacity in Gallons Dosing Volume Storage Capacity (1 % days) Pump Displacement Volume from tank bottle to pump base Total tank capacity Pump Tank Information Manufacturer Updated 10/12/04 Size Gallons per inch 4 Friction Loss per 100 feet of Plastic Pipe In.feet of head Gn M1 e Diameter 1/2 in. 2 in. 2 1/2 in. 3 in. 4 in. 5 in. 1 2:08 0.51 4:16 1.02 0.55 0.1'4 0.07 . 23.44 5.73 1.72 0.44 0.22 0.066 0.038 0.015 43.06 10.52 3.17 0.81 0.38 0.11 0.051 0.021 �F77 10 82.02 20.04 6.02 1.55 0.72 0.21 0.09 0.03 15 42.4.6 12.77 3.28 1.53 _ 0.45 0.19 .0.07 20 72.34 21.75 5.59 2.61 0.76 0.32 0.11 0.03 25 �� 32.88 8.45 3.95. 1:15 0.49 0.17 0.04 30 �� 46.08 11.85 5.53 1.62 0.68 0.23 0.06 0.02 35 �� 15.76 7.36 2.15 0.91 0.31 0.08 0.03 40 �� 20.18 9.43 2.75 1.16 0.40 0.11 0.03 45 �� 25.10 11.73 3.43 1.44 0.50 0.13 0.04 50 �� 30.51 14.25 4.16 1.75 0.60 0.16 0.05 60 19.98 5.84. 2.46 0.85 0.22 0.07 70�� 7.76 3.27 1.13 0.30 0.10 75 3.71 1:28 0.34 0.11 80 �� 9.94 4.19 1.44 0.38 0.13 90 �� 12.37 5.21 1.80 0.47 0.16 100 125 �� 9.58 3.31 0.88 0.29 150 E71�� 13.41 4.63 1.22 0.40 175 6.16 1.63 0.54 200 250�� 11.93 3.15 1.05 300 4.41 1.46 Updated 10/12/04 5 Friction Loss in PVC Fittings The follow table lists friction loss in PVC pipe fittings as a measure of the amount of friction in an equivalent length (ft) of straight pipe. VC., Parte Normal Pipe Size in 1/2" 3/4" 1" 11/4" 11/2" 2" 21/2" 3" .4" 90° elbow, standard I1.5 2.0 2.25 45° elbow, standard 0.75 1.01 .4 1.75 2.0 2.5 3.0 4.0 5.0 Insert Coupling 0.5 0.75 F170 1.25 1.5 2.0 3.0 3.0 F470 Gate Value ®m 0.6 0.8 1.0 1.5 1.6 2.0 3.0 Male -Female Adapter I .1.0 1.5 2.0 2.75 3.5 4.5 6.5 9.0 Tee -Flow through Run 1.0 1.4 1.7 2.3 2.7 4.3 5.1 6.3 8.3 Tee -Flow through Branch 4.0 . 5.0 6.0 7.0 8.0 12.0 15.0 16.0 22.0 Updated 10/12/04 6 SEPTIC PUMP SYSTEM WORKSHEET SANTA CLARA COUNTY ONSITE SYSTEIVIS MANUAL PART 4 d Ix Onsite Systems Manual- Part 4 Page 1 GUIDELINES FOR ALTERNATIVE SYSTEMS INTRODUCTION "Alternative System" means a type of OWTS that utilizes either a method of wastewater treatment other than a conventional septic tank and/or a method of wastewater dispersal other than a conventional drainfield trench for the purpose of producing a higher quality wastewater effluent and improved performance of and siting options for effluentzdispers-al. This partof the Onsite Systems Manual provides guidelines -`f& the design. and application of various alternative onsite wastewater treatment and ,disposal technologies suited to the conditions and constraints in Santa Clara County. b These guidelines provide the technical criteria and`r-standards provided by Santa Clara County Code Section B11790.throul followed for both new development and -repair situations;: x provide for the use of alternative OWTS as the basis`fo Schematic and cross-section diagrams are included to illustr� type of system."`.`` ALTERNATIVE TREATMENT SYSTEMS Guidelines are provided for the follow • Intermittentrand RE Proprietary Treatm • Other,.a.lternative tre rcula x the use of alternative OWTS as ,B1•1--95, and are ntended to be rota Clara County Code does not new lot creation (subd ivisions). the key design features of each U ing alternative treatment systems: Sand Filters..,> is approved by the director and the appropriate California Regional-WateY Quality Control Board(s). -" ALTERNATIVE DISPERSAL SYSTEMS . Guidelines are\provided for the following types of alternative dispersal systems. ® Shallow Pressure Dist`ritution i Mound �' {/ �V i At -Grade + Pressure-Dose&S nd Trench Raised Sand Filter Bed Drip Dispersal, and * Other alternative dispersal systems approved by the director and appropriate California Regional Water Quality Control Board(s). Onsite Systems Manual - Part 4 (9/2013) Page 1 SITING CRITERIA All requirements specified in section B11-67 of Santa Clara County Code for conventional OWTS also apply to alternative OWTS,with the following clarifications and exceptions. Horizontal Setbacks. Horizontal 'setback requirements for alternative treatment systems are the same as those specified in section Bll-67 for septic tanks. Horizontal setback requirements for alternative dispersal systems are the same.as those specified in section B11-67 for conventional dispersal systems. it Areas of Flooding. Alternative OWTS shall not be located in areas subject to flooding as defined by the limits of the 10 -yr floodplain, determined or, estimated from published floodplain maps or on the basis of historical, evidence acceptable to the director. Alternative OWTS shall be located and designed to avoid contamination of or: damage from inundation by floodwaters during a,1'00 -year flood event. As`kapproprjate, such measures shall include: 1) protecting ATS supplemental treatment, pressure distribution and/or drip dispersal components;from`JJ6od�damage using structural tie - downs and/or elevating critical components 'above the 100 -year flood level; 2) preventing discharge of wastewater into flooded dispersal areas from pump systems (e.g., using flood -activated float ``swit hes to override%disable. pump: operation during high water conditions); ), and 3 ) providing -additional emergency storage capacity for flood periods. Ground Slope. ,fVlaximumground slope for different types of alternative wastewater dispersal systems are as follows: Maximum Ground,Slo _e for Alternativ&,Wastewater Dis ersal Sys ms T... pe of Dis osal System ----_,200/a/ 30% 40% 50% ex/Mound;�<• X '+ At -Grade � n • .,Raised Sand Filter Bed X i Shallow Pressure'Oistributio6/ • Pressure -dosed Sand Trench X • Subsurface Drip Dispersal X Related Requirements: /Any disposal system located on a slope greater than 20 percent shall require the completion;and approval of a geotechnical report per Code section .B11-83. Vertical Separation to Groundwater. Where alternative OWTS are used, minimum vertical separation distance to groundwater, measured from the bottom of the dispersal system to the seasonal high water table, may be reduced from the requirements that apply to conventional OWTS (per section 611-67 of the County Code), as specified in the table below. See specific requirements for the type of alternative OWTS for additional restrictions on groundwater separation distances that may apply based on system size (L.P., volume of wastewater flow) or for particular site conditions or geographic areas. Onsite Systems Manual - Part 4 (9/2013) Page 2 Minimum Vertical Separation Distance to Ground Water for Alternative OWTS (feet)' 'Measured from the bottom of the dispersi Soil Depth. Minimum depth of pe`rmea shall be as specified in the table�,b Permeable soil is defined as having a�K or having a cla contentof less tha system to th6 seasonal high water table. le soil beneath thebottom of the dispersal field low for different,titypes of alternative OWTS. rcolation it td, . ,120 minutes per inch or faster ;60 percent shall not include solid rock formations or,, those that`;"�ontain continuous channels, cracks or fractures. Design �; requirements4for'•alternaive OWTS prescribed in the Onsite Systems Manual may impose additional soil depth requirements based on system size (i.e., volume of wastewater flow) or for p titular site R f;✓ Mmrmum SoilZDepth Bene V �hditions or geographic locations. Alternative OWTS (feet)' Percolation Vertical Separation to Type of OWTS Rate Groundwater (feet):L 2' 3' 5' 8' • Shallow Pr0ssure,'tDistribution Trench (PD) (MPI) ® Conventional Trench w/ Supplemental Treatment 1-5 6-30- X X 31-120 X • At -Grade w/Supplemental Treatment Shallow Pressure Distribution (PD) 1-5 X X At -Grade 6-120 x,:," f �. X 0 Raised Sand Filter Bed, w/Supplemental Treatment & Drip Dispersal Shallow PD w/Supplemental Treatment . At -Grade w/Supplemental Treatment' Mound ��, 15i X Pressure -dosed Sand Trench (PDST). 6;120- X Raised Sand Filter Bed - Subsurface Drip Dispersal w/Supplemental%' Treatment ?. "IN Raised Sand Filter Bed, w/Supplemental 1-5.Aa X �f{ Treatment & Drip Dispersal 6420 X 'Measured from the bottom of the dispersi Soil Depth. Minimum depth of pe`rmea shall be as specified in the table�,b Permeable soil is defined as having a�K or having a cla contentof less tha system to th6 seasonal high water table. le soil beneath thebottom of the dispersal field low for different,titypes of alternative OWTS. rcolation it td, . ,120 minutes per inch or faster ;60 percent shall not include solid rock formations or,, those that`;"�ontain continuous channels, cracks or fractures. Design �; requirements4for'•alternaive OWTS prescribed in the Onsite Systems Manual may impose additional soil depth requirements based on system size (i.e., volume of wastewater flow) or for p titular site R f;✓ Mmrmum SoilZDepth Bene V �hditions or geographic locations. Alternative OWTS (feet)' 1 Measured from the bottom of the dispersal trench, bed or piping (drip dispersal only). Onsite Systems Manual - Part 4 (9/2013) Page 3 Minimum Soil Depth Type of OWTS feet ' 2• 3, .: i • Conventional Trench` w/ Supplemental Treatment • Shallow Pr0ssure,'tDistribution Trench (PD) X • At -Grade ® Shallow: Pb"w/Supplemental Treatment • At -Grade w/Supplemental Treatment • Mound • Raised Sand Filter Bed (Open Bottom Sand Filter) X • Subsurface Drip Disposal w/Supplemental Treatment 0 Raised Sand Filter Bed, w/Supplemental Treatment & Drip Dispersal 1 Measured from the bottom of the dispersal trench, bed or piping (drip dispersal only). Onsite Systems Manual - Part 4 (9/2013) Page 3 SITE EVALUATION, DESIGN AND CONSTRUCTION REQUIREMENTS Site evaluation, engineering plans, operation and maintenance guidelines, and other permitting requirements for alternative systems shall conform to all requirements for conventional OWTS as well as any additional requirements specified in this Manual for the type of alternative system proposed. Design and construction of alternative OWTS shall be in conformance with requirements in the this Manual. F /: � y � NA xy - f� �r s �0a r I Onsite Systems Manual - Part 4 (9/2013) Page 4 GUIDELINES FOR INTERMITTENT AND RECIRCULATING SAND FILTER SYSTEMS A. DESCRIPTION Intermittent sand filters (ISF) and recirculating sand filters (RSF) are used to provide supplemental treatment of septic tank effluent prior to discharge to•,tFie dispersal system. They are used to improve or restore the capacity of the dispersal field;,reduce pathogenic bacteria and can provide additional nitrogen removal.:.,,, Sand filtration is well established in sanitary engineering,,pra`cf ce for more than 100 years as a passive, reliable treatment process. An ISF consists .df -'a packed -bed filter,'of medium=grained sand, designed for single pass-through treatment of septic tank effluent; it is sometimes referred to as a "single pass filter". `� t•.' An RSF utilizes coarse-grained sand and a recirculation system, usually controlled by a timer that causes the effluent to pass through tWsand media several° -t mes prior to final dispersal. RSFs have the ability to produce effluent quality similar to ISFs, except that they are less effective in bacteria removal. However, RSFs typically provide;greater nitrogewremoval than ISFs, on the order of 50 percent reduction as compared with conventional septic tank effluent. Effluent from sand filters,may be discharged to',conventional'leachfields and to any type of alternative dispersal ,system identified in this Onsite Systems Manual. Effluent from an ISF or RSF designed and op'e`rated,.in accordance with these -guidelines will be considered to meet the criteria for "su lementaI treatment" B. CDNSTRAINTS,,ADDRESS li",- Used in combination withthe appropr ate"type of dispersal system; sand filters can be applied to addressthe following onsitewastewater constraints: 1. Hi h roundwater j 2. Shallow soil over fractured rock or coarse alluvium; 3. Shallow soil over impermeable soil or bedrock; 4.. Slow percolation at standard leachfield depths; 5. Steep slope; 6. Limited dispersal area; and Onsite Systems Manual - Part 4 (9/2013) Page 6 7. Nitrogen limitations (RSFs) C. SITING CRITERIA 1. Sand Filter Treatment Unit. All siting criteria for septic tanks, as specified in Santa Clara County Code Chapter 1311-67, shall also apply to intermittent and recirculating sand filters and associated tanks and pumping units. 2. Dispersal Systems Receiving Sand Filter Effluent. Dispersal systems,receiving sand filter effluent are subject to all siting criteria for conventional septic tank -dispersal trench systems, except as modified in accordance with adop 4: type of alternative dispersal system proposed, inclu.di incorporation of supplemental treatment. Allowa ce include reduced vertical separation distances,;or incre Refer to the adopted guidelines for the specific type c !dl"requirements for the specific . Eany allowances for the for supplemental treatment may ed wastewater•applica ion rates. dispersal system for dpplicable requirements ana suppiementai irea-cment aiiowances� D. DESIGN CRITERIA 1. Septic Tank Pretreatment. Sand fiilter`treatment units shallx b&preceded by a septic tank, sized for the projected sewage flow for the :structure &Jkility being served, determined in accordance wi h sewage flow,e'stima11tion guidelines in Part 3 of this Manual. 2. Pressure Dosing:/Septic-.tank effluent shall be applied to the sand filter treatment unit by pressure dosing; utilizing either an-autorr`iatic dosing siphon (intermittent filter only) or pump. The.pressure distribution system shall',be•designed in accordance with accepted engineeringpractices`to achieve, at a -minimum: (a')—Uniform.dosing of;effluent over the surface application area of the sand filter distribution bed;'\, . (Adequate flow.rate,,screening of effluent and suitable piping.network to ' . preclude solids accumulation in the pipes or clogging of discharge orifices; ,r (c) Suitable, access provisions for inspection, testing and adjustment of the pressu're'distribution system; (d) Dosing volume as follows: (1) Intermittent Sand Filters: Dosing volume to achieve a minimum of 3 to 5 doses per day at design flow conditions; and, (2) Recirculating Sand Filters: Timed dosing to achieve a recirculation rate of approximately 5:1 at -design flow conditions. (e) At least one distribution lateral for every 36 inches of bed width. Onsite Systems Manual - Part 4 (9/2013) Page 7 Additional requirements for the design and construction of pressure distribution systems contained in "Guidelines for Pressure Distribution Systems" shall also apply. 3. Wastewater Application Rate. The wastewater application rate used for sizing the surface area of the sand filter shall be as follows: (a) Intermittent Sand Filters: (1) 1.2 gpd/fti for individual residential OWTS Z (2) 1.0 gpd/ft for all commercial, industrial, msti itional, and multi - residential OWTS (b) Recirculating Sand Filters: (1) Maximum of 5.0 gpd/ftz for individual�r sidential O TSS,\ i (2) Maximum: of 4.0 gpd/ft for`all commercial] industrial, institutional, and multi-residentialOWTS" T Reduction in the above wastewater loading rates or other provisions to insure the long- term integrity and performance of. eh sand filter may required for high strength waste flows, such as those from restaurants . 4. Containment Liner. The sand filter shall be provided with an impermeable containment liner•to�.preent leakage out "o or into th`effilter. The liner shall consist of either: (a) 30 milplastic, (b)reinforced poured -in -placed concrete; or (c) an equivalent impermeable"structure or 6arner. J S. Finished Grade ,The finishedgrade of the and filter shall be at or above the surrou ding ground elevation. AboViez ound installation shall be structurally supported withre arcing--�wall(s), as reglured. Shape. The sarid filter shall not''be restricted as to its shape in plan view. 7.'Multiple Units. The sand filter may be divided into compartments or multiple units. 8. Sand Filter Mediap_,y (a) SandSp ecification. The sand media shall be a medium to coarse sand that 4a meetsthe gradation specifications in Table SF -1: (b) Sand Depth. The minimum sand depth below the.gravel distribution bed shall be 24 inches. Onsite Systems Manual -Part 4 (9/2013) Page 8 Table SF -1. Sand Specifications Sieve:Size Percent Passing Intermittent Sand Filter Recirculating Sand Filter* 3/8 100 100 #4 907-100 70-100 #10 62-100 5-78 #16 45-62 0-4 #30 25-55 -:%0-2. #50 5720 960 0-10 0-1 #160 0-4 0-1 #200 0-2 1. *Additional sand specifications for RSF Effective size of sand/gravel, Dlo 1.5 to 2.0 mm a Uniformity coefficient, Ur: X25 Documentation of laboratory sieve analysis results for the proposed sand fill material shall be supplied to DEH to verify'•onformance with the above, specifications, as applica6l1&, 9. Gravel Distribution Bed (a) Material. The distribution bed shall consist of 3/8 -inch double -washed pea gravel; substantially free of fin " ' , (b),¢ ---Depth. Pea�gravei``shall -extend-a°`minimum of 6 inches below the invert and 2 rw :. ,. inches above the top of the distribution piping. If the distribution piping is installed with cha bers,.the pea gravel depth below the distribution pipe may be reduced from 6 orches to 4 inches, and the 2 -inch pea gravel cover may be �. .. eliminated ,, w 10. Silt �Barrier. For an/ intermittent sand filter, the gravel distribution bed shall be, covered in its',entiretjf with a geotextile ("filter fabric") silt barrier. Filter fabric shall be either poly es ter,; nylon or polypropylene, or any combination thereof, and shall be suitable for.underdrain- applications. Filter fabric shall be non -woven, shall not act as a wicking agent and shall be permeable. Recirculating sand filters do not require a silt barrier. 11. Cover. (a) Intermittent Sand Filters: (1) Material. A soil cover shall be placed over the distribution bed, consisting of a medium, loamy -textured soil. Onsite Systems Manual - Part 4 (9/2013) Page 9 (2) Depth. Soil cover depth shall be a minimum of 12 inches and a maximum of 18 inches over the top of the distribution bed. Soil cover shall be crowned or sloped to promote rainfall runoff. (b) Recirculating Sand Filters: (1) Material. A granular media cover shall be placed over the distribution bed, consisting of clean gravel that. may range in size from 3/8 -inch pea gravel to 2 Y2—inch rounded rock. (2) Depth. Cover depth shall be a minimum of 12 inoies and a maximum of 18 inches over the top of the distribution bed, Y a 12. Underdrain (a) Material. The underdrain beneath the sand media shall consist of 3/8" washed pea gravel with 4 -inch diameter perforated drain pipe, installed,with perforations oriented down.° E. (b) Depth. The pea gravel underdrain shall3h�minimum depth of 9 inches. (c) Grade. The underdrain 'slall-be constructed and'the drain pipe set with a minimum grade of 1% tovvard*e-outlet point ` e (d) Watertight Outlet "Boot". The sand filter underdrain shall be equipped with a watertight- 'outlet "boot" for c nn'ection of piping to the dosing tank. An exceptiontothis. is for intermittent sand filters that are equipped with an internal'pump systm for direct�dosing to the disposal field (see paragraph #15 (e)=Clean out Riser F,or clean ourand inspection purposes the upslope end of the perforated, drain p peen the underdrain shall be equipped with a vertical riser constructed'of non -perforated pipe of equal diameter. The riser shall extend to 1,, 1, y finished grde of the and filter. 13 Air anifold. An air manifold shall be installed within the pea gravel underdrain for the purpose,ofAntroducing forced air to into the sand filter media, as needed, for maintenance''o:r'drainage rehabilitation. The air manifold shall consist of small diameter PVC piping, wits drilled perforations (pointed down), and positioned above the perforated underdrain pipe. The manifold shall be connected to a vertical leader pipe that extends to the surface of the sand filter, fitted with a threaded pipe cap or plug at the top where a portable air line can be connected. 14. Inspection Wells. An inspection well shall be installed in the gravel distribution bed of each sand filter compartment. The inspection well shall extend from finished grade to the pea gravel -sand interface of the distribution bed and shall be perforated in the pea Onsite Systems Manual - Part 4 (9/2013) Page 10 gravel zone only. Inspection wells shall be 2 -inch to 4 -inch diameter plastic pipe and fitted with a wrench -tight cap or pipe plug. Perforations shall consist of hacksaw slots at nominal 1" spacing; alternatively, commercially slotted pipe may be used. For. intermittent sand filters, inspection wells shall -be sealed against surface infiltration with a bentonite or concrete annular seal through the soil backfill zone. 15. Internal Pump System (ISF only). In lieu of gravity flow from the sand filter to the dispersal field (or dispersal field dosing system), an internal pump system may be installed within the intermittent sand filter for dosing directly to..the dispersal field. In such applications: (a ) pump chamber shall be seated at or below,the"bottom of the underdrain; C,,,- t' (b) pump operating depth shall be entirely within,the depthof,the uhderdrain; and, . :'f `• (c) storage volume equal to 50 pe cent.of--the disposal field dose vbume shall be provided in the network of perforated drain pipe within the underdrain. E. ENGINEERING PLANS AND CONSTRUCTION 1. Reference Guidelines. In addition to\.the requirements set'forth herein, design and construction of sand filter systems shall utiliie-applicab.le.guidelines contained in the following references:--, r +' a. "Onsite Wastewater Tr. eatment_Systeims Manual", U.S. Environmental Protection Age ncy,c ebruary 20021and as amended b. "Design -Manual=, Ons ite`Wastewater,Treatment and Disposal Systems", U.S. Environmental` Protection Agency, October 1980. 2 •:Engineering Plans:- Engineeeing,;plans for sand filter systems shall include: a. "'Allrelevant elevation data and hydraulic calculations; b. Specific'step-by-step construction guidelines and notes for use by the installer; c. Recommended make and model of all components; a � d. Recommended pump system components, with cut -sheet depicting float settings; e. Control panel programming; and f. An inspection schedule listing critical control points. 3. Construction Inspection. At a minimum, inspection of the sand filter system installation should include the items listed below. Joint inspection by the designer, contractor, and DEH may be required. Onsite Systems Manual - Part 4 (9/2013) Page 11 Pre -construction inspection where the construction staking or marking of the sand filter is provided and construction procedures.discussed; Water tightness of septic tank and dosing -(pump) tank; Sand filter dimensions, structure and liner; Underdrain piping and filter rock; yt ,` Sand quality and placement; _N . 1 Piping installation and hydraulic ("squirt") test,of\th•e,distribution�system; Functioning and setting of all control devices; and r� � �•.� Vii'`` y: Final Inspection to verify that all construction elements are in confor ace with the approved plans and specifications, all inspection,wells are installed; and erosion control has been com leted.` — �+ � ''E� F. MANAGEMENT REQUIREMENTS. Recommended minimu'rh-procu edieAes and fre and reporting activities for intermittent and Table SF -2. ncy for inspection, maintenance, monitoring rculating sand filter systems are outlined in Onsite Systems Manual - Part 4 (9/2013) Page 12 Table SF -2. Intermittent and Recirculating Sand Filter System Management Requirements f Onsite Systems Manual - Part 4 (9/2013) Page 13 Work Frequency Inspection ■ Observe surface conditions on and around filter for effluent leakage, According to permit conditions, drainagetinfiltration, erosion or other problems. typically every 6 to 12 months, ■ Checklmeasure water level in inspection wells in filter bed. depending on system size, ■ Perform all inspection work as recommended by designer or usage, and history. equipment manufacturer. ■ Perform inspection protocol for pump chambers (see Guidelines for ;.• Dosing Pump Systems). .r'''te ■ Record observations.J` Maintenance ■ Purge laterals. ; `-� According to permit conditions, ■ Perform squirt and balance laterals. j` typically every. 6 to 12 months, ' depending on system size, ■ Exercise valves to ensure functionality. , usage, arid.history. ■ Perform all maintenance work as recommended by designer oar equipment manufacturer. % Responsive�'maintenance as necessary. ■ Record work done. ?, • W". Water ■ Report observation findings and maintenance actions including According to permit conditions, Monitoring & notation of problems and corrective actions. ' ' -; if applicable. Sampling ■ Record dose.counter and elapsed time metecreadings from control panel. ,= _ �`. Reporting ■ Repot f ndings to DEH`perfpermit requirements. According to permit conditions, ■ Standard report to describe findings, analyze performance, and typically every 1 to 2 years, detail action`taken. s depending on system size, f e ". Report°emergency or_failure conditions;to�DEH immediately. � ti usage, history, location. f Onsite Systems Manual - Part 4 (9/2013) Page 13 30 MIL PVC LINER, (TYP.) TO GRADE SECURE TOP EDGE BY PVC GATE VALVE pot FASTENING TO'BOARD UTILITY BOX (TYP.) (TYP.) \\ CLEANOUT WITH Co-� 0 0 Ilr—i Oa THREADED CAP (TYP.) A — -oo° ab pC'P dtPoD q, dtPoD Ro O D4�bo 12" TO 18" (TYP.) goo OCP dlfbo o° o° - pp O oD O fb O -lb%O 24" TO 36" (TYP.) OD OC Op _ OD Ql Dw- % Q& db%o DO 2" PVC END J MANIFOLD CLEAN OUT WITH THREADED CAP (TYP.) 2" PRESSURE LINE FROM PUMP CHAMBER #1 PLAN VIEW STANDARD ORIFICE SHIELD OR CHAMBER OVER EACH LATERAL (TYP.) 4" SCH.40, PVC SLOTTED COLLECTION PIPE INTERMITTENT SAND FILTER PLAN VIEW INSPECTION RISER (TYP.) TO GRADE o aINSPECTION WELL (TYP.) pot UTILITY BOX (TYP.) Co-� 0 0 Ilr—i Oa 4" SCH.40, PVC SLOTTED COLLECTION PIPE INTERMITTENT SAND FILTER PLAN VIEW INTERMITTENT SAND FILTER WITH INTERNAL PUMP BASIN PEA GRAVEL DISTRIBUTION BED; 6" MIN. BELOW PIPE, 2" DISCHARGE MIN. ABOVE PIPE HOLES W/ INSPECTION WELL SHIELD, OR FILTER FABRIC END RISER & FLUSH EQUAL (TYP.)* SILT BARRIER PORT UTILITY BOX INTERNAL (TYP.) PUMP BASIN, 4" UNDERDRAIN 30" DIA. PVC CLEANOUT MANIFOLD (-pip) PERIMETER RETAINING r i / STRUCTURE 12" (TYP. �/ T OIL —ATO DISPOSAL FI i i (TYP.) a- rrpo,.j °-uaw �8 4 30 MIL PVC �r �� LINER OR PRESSURE e, w o.° ° ° ° ° 6 wg g�� e ° o °a as€ EQUAL LINE FROM �° "Mlo a DOSING PUMP =- PERFORATED PVC ? t AIR INJECTION LATERAL MEDIUIM COURSE SAND 24" MIN. DEPTH i MANIFOLD; W/ SHUT-OFF VALVE CONNECTION PORT AT SAND DISTRIBUTION FILTER SURFACE LATERAL DOUBLE WASHED PEA 4.00 ° vso�° °�°o�q,�„°��°°� °°;° FOR PORTABLE :: _ _ _- BLOWER 4 SLOTTED?SLOP` UNDERDRAIN `—E x'•02 � �` g *NOTE: DISCHARGE HOLES SAND BEDDING` om MAY BE SHIELDED WITHIN A ..«.: (TYP.) CONTINUOUS PLASTIC CHAMBER, OR THEY MAY BE ORIENTED DOWN WITHOUT THE NEED FOR ANY SHIELD. INTERMITTENT SAND FILTER WITH INTERNAL PUMP BASIN PRESS LINE F DOSING P LATERALS DISTRIB LA PEA GRAVEL DISTRIBUTION BED; 6" MIN. BELOW PIPE, 2" MIN. ABOVE PIPE FILTER FABRIC SILT BARRIER UTILITY BOX (TYP.) MANIFOLD —i DISCHARGE HOLES W/ SHIELD, OR EQUAL (TYP.)" INSPECTION WELL END RISER & FLUSH PORT 4" ,UNDERDRAIN CLEANOUT PERIMETER oma- $�� - .-- --•- _ : - SLOPE A.02\ SLOTTED UNDERDRAIN SAND BEDDING,. (TYP.) RETAINING STRUCTURE (TYP.) ' 30 MIL PVC LINER OR �— EQUAL ' PERFORATED PVC AIR INJECTION MANIFOLD;.W% CONNECTION PORT AT SAND FILTER SURFACE FOR PORTABLE BLOWER NOTE: DISCHARGE HOLES . CONTINUOUS PLASTIC p CHAMBER, OR THEY MAY BE O 0O `:Do po0'g0o 'o0 o°c 0 O opo o°°o °0 o°coo?,00. RETURN LINE TO THE NEED FOR ANY SHIELD. RECIRCULATION TANK p o$0 I p p oo$ 0c 1 RIVER RUN ROCo0�a'80 p$�o �o1 o •°D. 11..^dar dVIow c c�''.o ° °°•9 LIREws -.-}r• ✓°Odd' -DOS D OD° D °y„g� oD �$ •'° ROM JMP HUT -OFF 'MEDIUIM COURSE SAND 24" MIN. DEPTH VALVElo JTION u n ( °°$M ° DD° &�' o DOU LE ASHED P_E� GRAVEL° p=�a=o DD gg �q � ° °D°"`1Dp°°°4orYXo° FERAL QQQQ�D 8l 8 0° ride � o oma- $�� - .-- --•- _ : - SLOPE A.02\ SLOTTED UNDERDRAIN SAND BEDDING,. (TYP.) RETAINING STRUCTURE (TYP.) ' 30 MIL PVC LINER OR �— EQUAL ' PERFORATED PVC AIR INJECTION MANIFOLD;.W% CONNECTION PORT AT SAND FILTER SURFACE FOR PORTABLE BLOWER RECIRCULATING SAND FILTER NOTE: DISCHARGE HOLES MAY BE SHIELDED WITHIN A CONTINUOUS PLASTIC CHAMBER, OR THEY MAY BE ORIENTED DOWN WITHOUT . RETURN LINE TO THE NEED FOR ANY SHIELD. RECIRCULATION TANK RECIRCULATING SAND FILTER GUIDELINES FOR PROPRIETARY TREATMENT UNITS A. DESCRIPTION Propriety treatment units cover a category of manufactured or "package" systems specifically developed for residential and other small-scale sewage treatment applications. Most proprietary designs currently available fallinto two general categories: (fyaerobic treatment units (ATVs) and (2) media filters. 1. Aerobic Treatment Units (ATVs). ATUs utilize forcediair�to oxidiz °the wastewater, promoting aerobic decomposition of the wastewater�solids. These'systems provide supplemental treatment of wastewater for iri provement in dispersal' field performance; they also provide varying degrees of nitrogen. emoval. In.general, ATUs co/n,6e relied on to produce secondary quality effluent, better.than`30 mg'/L BOD and TSS. ATUs are generally not as effective in reducing pathogen levelsassystems that incorporate media filtration. However, some'ATUs,provide reduction •in\nitrogen levels equal to or greater than that provided by sand,filtersnd.other media;filtes. 2. Media Filters. This includes proprietary designs "that'funetion similar to sand filters. In these systems the" is replaced with\\ h'�alternate;!, "edia; peat, gravel or textile are a few examples.'il xtile and. `other media filters have been found to produce effluent quality reasonabl :similar to)recirculatin sancapabilities Pd=filters, and provide similar abilities in overcoming various Sol hand -site constraints. Effluent,from propriet6ry-treatrheht,units may be discharged to conventional dispersal trenches and to'any type of alternative dispersaFsystem identified in this Onsite Systems Manual. Effluenf'from proprietary treatment units designed and operated in accordance with these guidelines will be considered'to meet he criteria for -"supplemental treatment". B. CONSTRAINTS'•ADDRESSEW/ Used in combination with `the appropriate type of dispersal system, proprietary treatment units can be applied to address the following onsite wastewater constraints: 1. High groundwater; 2. Shallow soil over fractured rock or coarse alluvium; 3. Shallow soil over impermeable soil or bedrock; 4. Slow percolation at standard leachfield depths; Onsite Systems Manual - Part 4 (9/2013) Page 14 5. Steep slopes; 6. Limited dispersal area; and 7. Nitrogen limitations. C. SITE CRITERIA 1. Treatment Unit. All siting criteria for septic tanks, as sp Code Chapter B11-67, shall also apply to proprietary tre tanks and pumping units. 2. Dispersal Systems Receiving Proprietary Treatr receiving effluent from a proprietary treatment conventional septic tank -dispersal trench sysfer with adopted requirements for the specific typE proposed, including any allowances.for the inco Allowances for supplemental treatment may in( distances, increased wastewater application rat to the adopted guidelines for the spe if `type c requirements and supplemental treatment.,61W D. DESIGN AND CONSTRUi 1. NSF Standard 40 Sanitation Found evaluation, or..ha Standard 40 per�f ,'- installed in accord NSF`Standard 40. flows IREMENTS n'Santa Clara County units and associated �ht,Effluent Dispersal systems . nit are subject to all,ysiting criteria for except as modified in; ccordance )f�alteeri' iue dispersal system )oration of supplemental treatment. r ide`reduced vertical separation � F > or modified slope restrictions. Refer dispersal system for applicable eThe proprietary treatment -unit shall be listed by the National anon (NSF) as meettng the/NSF.Standard 40, Class 1 performance ve certification by a -third -party listing agency as complying with NSF ormance recjuirements. The treatment unit shall be manufactured and ance with the de ign specifications used to determine compliance to THis specification is applicable to.treatment units for wastewater to 1,500 gpd and is based on compliance with .US EPA standards for secondary trbatment`d municipal wastewater, including 30 -day average effluent limits of 25 mg/L for_CBOD5 and 30 mg/L for TSS. Treatment units for flows=in excess of 1,500 gpd will require%certification by a third -party listing agency of equivalent performance. 2. Design Sewage Flow. Sizing and design of proprietary treatment units shall be based on the projected sewage flow for the structure or facility being served, determined in accordance with sewage flow estimation guidelines in Part 3 of this Manual. 3. Tanks. All tanks housing a proprietary treatment unit shall be structurally sound, water- tight and capable of withstanding 1,000 pounds of weight. Onsite Systems Manual - Part 4 (9/2013) Page 15 4. Controls. Control panels shall be designed and configured in such a manner that, in the event of a treatment unit malfunction, an alarm system will be triggered and discharge from the treatment system to the dispersal field will be interrupted until the treatment unit malfunction is rectified. At a minimum, the alarm system shall include an audible and visual alarm located -within the building served by the. system. 5. Compliance with Manufacturer Requirements. The designer and installer shall follow the proprietary manufacturer's design, installation, construction, and operations procedures. 6. Engineering Plans. Engineering plan submittals for proprietarytreatment units shall provide documentation of compliance with manufacturer requirements and sufficient design analysis to verify the appropriateness of -the -treatment unit f& -the proposed application. Engineering plans shall contain,specific step-by-step construction guidelines and notes for use by the installer,.including anymanufacturer instructions. 7. Installer Requirements. Anyone installing a propretai and certified by the system manufacturer. Documentz' this requirement shall be provided_to DEH prior to syst 8. Maintenance Contract. The applica t\must demonstrate that a written maintenance agreement with a qualified service provider'has beWbbtained for the proposed proprietary. treatme t un t to ensure satisfactory post -construction operation and maintenanee�A rnaintena'n a agree ment'must,be maintained valid for the life of the treatment unit N �' 1 9. Constructiorn;lnspection The following minimum inspections prior to commencing /constructionor covering any elements of the system shall be required. Joint inspection Eby the designer, installer, and�SA 'Clara County DEH maybe required. ,k ti `E°f a P're-construction inspection where the.construction staking or. marking of the ti=e mr,ent unit; s to be placed and installation procedures are discussed; treatment unit shall be trained Op verifying conformance.to n�mstallation. b. Testingofthe treatment unit: L Function and setting of all control devices and alarms. ii. Water -tightness of septic tank, treatment tank(s), and dosing tank, as applicable. c. Final Inspection: Onsite Systems Manual -Part 4 (9/2013) Page 16 L A letter from the designer that the treatment unit has been installed and is operating in conformance with design specifications shall be provided. ii. A valid, signed maintenance agreement between the applicant/property owner and service provider shall be provided. E. MANAGEMENT REQUIREMENTS Recommended minimum procedures and frequency for inspection, maintenance, monitoring and reporting activities for proprietary treatment systems are outlin' elnTable P-1 below. f Table P-1. Proprietary Treatment System Management Requirements Onsite Systems Manual — Part 4 (9/2013) Page 17 Work : _ Frequency Inspection Inspection to be in accordance with manufacturer specifications., According,to per7f ft conditions, �* typically every 6 to 12 months, ''' depending'on system size, usage, and history. Maintenance Perform all maintenance as regwred and in accordance with''_ ■ ' According to permit conditions, equipment manufacturer specifications � , typically every 6 to 12 months, s? 7 depending on system size, z usage, and history. Water Monitoring to be in accordance with manufacturer speafications` If required, according to permit Monitoring & Sampling conditions, typically. every 6 to 12 months, depending on system size, usage, and history. Reporting Report findings"t6 DEH oer permit.requirements% According to permit conditions,. ■ ZStandard report 'to descfibe findings analy e'performance, and typically every 1 to 2 years, detait6dtiions taken` depending on system size, f, r Report cns�s or,failure conditions toJDEH immediately. usage, history, location. Onsite Systems Manual — Part 4 (9/2013) Page 17 GUIDELINES FOR SHALLOW PRESSURE DISTRIBUTION SYSTEMS A. DESCRIPTION Shallow pressure distribution (PD) systems are a variation of a_ conventional gravity drainfield system that use a pump and small -diameter pressure piping to achieve broad, uniform distribution of wastewater in the shallow soil zones for improved soil absorption and better treatment of percolating effluent. This type of design, especiallyin conjunction with . supplemental treatment, is well suited for steeper terrain and shallow soil conditions. B. CONSTRAINTS ADDRESSED ;= 1. High groundwater; 2. Shallow soil over impermeable soil or bedrock; 3. Shallow soil over fractured rock or coarse alluvium;, 4. Slow percolation at standard dispe sal,trench depths; and 5. Steep terrain.` : f C. SITE CRITERIA 1. Setbacks. Hor'iizontal setback requirements f6r_shallow PD systems shall be those applicable to conventional dispersal fields, as}specified in Santa Clara County Code section 2. Vertical Separation Requirements. to GrouriclWater. i.Minimum depth to seasonal high groundwater for \,shallow PD systems, as measured from trench bottom, shall vary according to soil percblation rate'as shown in Table PD -1. b. Soil Depth. Minimum depth of soil, as measured from trench bottom to impermeable soil or rock, for shallow PD systems shall vary according to soil percolation rate and the level of treatment provided as shown in Table PD -1,: 3. Percolation Rate. Average percolation rate for shallow Pb systems shall be within the range of 1 to 120 minutes per inch (MPI), as determined in accordance with standard percolation requirements for conventional dispersal trenches. Onsite Systems Manual - Part 4 (9/2013) Page 18 Table PD -1 Minimum Vertical Separation Requirements for Shallow PD System (feet, below trench .bottom) Percolation Rate Depth to Groundwater Soil Depth Primary Supplemental Primary Supplemental (MPI) Treatment* . Treatment* Treatment** Treatment** 1-5 5 3 3 2 6-120 3 2 3= 2 * Provided by a septic tank sized and constructed in accordance�witfi`requirements in Part 3 of this Manual. ** Provided by an approved alternative treatment system idenfified in this Manual 4. Ground Slope. a. Maximum ground slope in areas used',,fo shallowIPD systems sha111,.6ea,40 percent. b. Any shallow PD system located.on slopes greater th'ai 20 percent shall require the completion of a geotechnical report and slope -stability analysis as specified in Santa Clara County Code section 611-83., 5. Dual System. Per Santa Clara County `Code section B,,-67(d);„two shallow PD dispersal IA fields, each one hundred percent of the4totaksiz requ ired for the design sewage flow, shall be installed and interconnected ith=an approved: I w diversion device (pressure - rated), intendedrto'allow alternate use of th'e two fields. D. DESIGN CRITERIA 1. Treatm nt The following treatment requirements shall apply in connection with the use of shallow PD systems, P'ri;mary (septic,tank) treatment shall be the minimum level of treatment, and shall b"e acceptable where applicable vertical separation distances are met per Table PD1: b. Supplemental treatment, using an approved alternative treatment system identified'in this Manual, may be used to allow compliance with reduced vertical separation distances as provided in Table PD -1. 2. Design Sewage Flow. Shallow PD systems shall be designed on the basis.of the projected sewage flow for the structure or facility being served, determined in accordance with sewage flow estimation guidelines in. Part 3 of this Manual. Onsite Systems Manual - Part 4 (9/2013) Page 19 3. Pressure Dosing. Septic tank effluent shall be applied to the shallow PD system by pressure dosing, utilizing either an automatic dosing siphon or pump system. The pressure distribution system shall be designed in accordance with accepted engineering practices to achieve, at a minimum: a. Uniform dosing of septic tank effluent throughout the system of shallow PD trenches; b. Adequate flow rate, screening of effluent and suitable piping network to preclude solids accumulation in the pipes or clogging of discharge orifices; c. Suitable access provisions for inspection, testing and adjustment of the pressure distribution system; and •. d. Dosing volume to achieve minimum of 3 to 5 dosk,per day at design flow conditions.` 4. Dispersal Trenches. Shallow PD trenches shall' conform to the same design"and , construction requirements as conventionai,,trenches, perrPart 3 of this Ma l"" with the exception that the piping system shall consist of ress.y4a,piprn rather thar'jgravitY piping. g• 5. Pressure Distribution Piping. a. Pressure -Rated Pipe Material: All�. pipe, fittings ari'dAlves shall be pressure - rated PVC pipe, minimum 15O,.psi. b. Solvent Welded., All joints in the, pressure pipingstem shall be solvent welded. C. Pipe Siiing. All pressure distribution pipes and fittings, including transport . lines; manifblds, laterals and valves`; must be adequately sized for the design flow, and sha-Il berdesigned-to minimize frictional losses to the maximum extent 7 - Thrust Thrust Blocks:,, Concrete -th'r'ust blocks, or equivalent restraint, shall be.provided at sharp changes in pip",!ng directions. e. �' Shut-off Valves.' The distribution lateral for each trench shall be fitted witha sh`ut,off valve'tb adjust or terminate the flow to individual trenches. This valve may be either a ball or gate valve, and shall be located in a utility/valve box. f. Laterel'End Riser. The end of each lateral shall be fitted with a 900 long sweep to facilitate line cleaning and hydraulic testing. The end riser pipe shall also be fitted with a ball valve and/or threaded end cap or plug, housed in a valve box. 6. Pump System.. The pump system shall be: (a) appropriate for sewage applications; (b) of the size and type to meet the hydraulic design requirements; and (c) designed and Onsite Systems Manual - Part 4 (9/2013) Page 20 constructed in accordance with pump system requirements provided in Part 3 of this Manual. 7. Wastewater Application Rates. The wastewater application rates used for sizing the infiltrative surface (trench bottom and/or sidewall area), shall be based upon representative percolation test results for the soilzone corresponding with trench bottom depth, and the loading rate criteria in Table PD -2. Table PD -2. Wastewater Application Rates for Shallow PD Systemi Percolation Septic Tank Supplementa`htreatment Rate Treatment (MPI) Standard Rate Standard Rate2° '---"Enhanced Treatment- (gpd/ft)2 2' .� (gpd/ft.:l 3 Rate ;, 4 'Multiplier,_., (gpd/ft2) 1-5 1.2 '. 10 0.80. ' 0.80 A 1.2_-- 24 0.60 J, ;'\0.60 �`_ 1.2 2 0 30 0.56 NZ 6 fia ` a 1.12 2•:0 45 0.45 0-.,'45T 0.68 15 60 0.35 0 35 , . 0.53 1S 90 0.20' 0.20` 0.25 1'25 91-120 0.200.20 .25 1:25 y Interpolate between reference values for other percolation rateFiAee end of Part 4 for expanded table listing interpolated values.�',� Z Applies where supplemental treatment is'used in.connectidn with reduced depth to groundwater and/or reduced soil depth f. 3Applies wh r standard vertical separation distances are met. 4 Zia. 1 For informatiori oniv. Y , Reduction -in -the above wasteWbter-loading rates or other provisions to insure the long- term -in -e—grity ong- term integrity and;performance of the shallow PD trenches may be required for high strength waste flows„such astfrom restaurants. 8. Trench Sizing. The required square footage of trench infiltrative surface shall be calculated based on the,'design flow and the applicable wastewater application rate per Table PD -2 The required length of trench shall be calculated based on the combined bottom area aricl trenefi sidewalls, up to a maximum of four (4) square feet of effective infiltrative surfa`cesper lineal foot of trench. For example, this may be comprised of: (a) 1.5 -ft wide botto"m area plus two sidewalls of 1.25 feet each; (b) 2 -ft wide bottom area plus two sidewalls of 1 foot each; and so on. 9. Inspection Wells. A minimum of three (3) inspection wells shall be installed within and around shallow PD systems for the purpose of checking groundwater levels, and may also be used for water quality sampling, as needed. Inspection wells shall extend to a depth of 3 feet below the bottom of the PD trenches or to contact with impermeable materials, whichever is less. The inspection wells shall be located and constructed as follows: Onsite Systems Manual - Part 4 (9/2013) Page 21 a. One shall be located. upslope of the dispersal field, typically 10 to 15 away, to serve as a background or control well; b. One shall be located within the dispersal field, typically between trenches near the center of the field;. c. One shall be located down-slope: of the dispersal field, typically 10 to 25 feet horizontally from the lowest trench(es), and positioned to provide a representative point for monitoring the area estimated to be in the probable flow path of percolating wastewater;. d. Inspection wells shall be constructed of 2" to 4" diamet6(pipe, equipped with a wrench -tight cap or pipe plug, and a bottom cap. AII;Wells:shall be perforated beginning at a depth of 18 inches below grade andextending"Jo the bottom of the pipe. Perforations shall consist of hacksaw slo&at nominal 1".,spacing, or equivalent commercially -slotted pipe. To prevent surface water infiltration;.inspection wells shall be sealed with a bentonite or concrete annular seal (or equivalent•) toy a depth of 12 inches, minimum. '� f .1 4 . »\ E. ENGINEERING PLANS AND CONSTRUCTION 1. Reference Guidelines. In addition'to the_requirements set -forth herein, design and construction of shallow PD systems'shall utilize applicableg idelines contained in the following references; a. "Onsite Wastewater Treatment Systems Manual", U.S. Environmental Protection Agency,<,February 2002iand as-amendd&_.,} b. "Design Manual . Ons to Wastewater.T,reatment and Disposal Systems", U.S. Environmental Protection Agencv;-October 1980. 2/—,,`Engineering Plans`.-,, Engineering plans for shallow PD systems shall include: a. i"AII'relevant elevation data and hydraulic calculations; b. Specific�step-by-step construction guidelines and notes for use by the installer; c. Erosion control plan for any site over 20%, utilizing cover fill or with design flow >1,000 gpd:., d. Recommended make and model of all components; e. Recommended pump system components, with cut -sheet depicting float settings; f. Control panel programming; and g. An inspection schedule listing critical control points. Onsite Systems Manual - Part 4 (9/2013) Page 22 3. Construction Inspection. At a minimum, inspection of the shallow PD system installation should include the items listed below. Joint inspection by the designer, contractor, and DEH may be required. Pre -construction inspection where the construction staking or marking of the various system components is provided and construction procedures discussed; * Watertightness of septic tank and dosing (pump) tank; Layout and excavation of dispersal trenches and piping;`<', Y Drain rock material and placement; +� Piping installation and hydraulic ("squirt")gest of the distnbution.,system; �X` 4 Functioning and setting of all control°devices;\and * Final Inspection to verify that all construction elements are in conformance with the approved plans and specificatons,ceall performanwe,lls.are installed; and erosion control has been completed. � f tis F. MANAGEMENT REQUIREMENTS Recommended minimum' procedures and frequency for inspection maintenance, monitoring and reporting activities for�shallow pressure distribution systems are outlined in Table PD -3. Onsite Systems Manual - Part 4 (9/2013) Page 23 Table PD -3. Shallow Pressure Distribution System Management Requirements Onsite Systems Manual - Part 4 (9/2013) .Page 24 Work Frequency. ■ Conduct routine visual observations of disposal field and downslope:area and surroundings for wet areas, pipe leaks or damage, soil erosion, Every 6 to 12 months. Inspection drainage issues, abnormal vegetation, or other problems. ■ Perform all inspections of pump and appurtenances (see Guidelines for Dosing Pump Systems). ■ Purge laterals, squirt and balance. Distribution system ■ Exercise valves to.ensure functionality. maintenance annually. ■ Perform all maintenance work as recommended by equipment •Other maintenance as manufacturer for any special valves or other components. required. Maintenance ■ Investigate and repair erosion, drainage or other disposal field problems as needed. ■ Investigate and perform distribution system corrective wdrk, as�equired.'P'' ,\ ■ Record work done. ■ Measure and record water levels in trench observation wells.�` Measure trench water levels Water : Measure and record water levels in dispersal fieldwells, as annually. ; Monitoring & "monitoring applicable, per permit requirements. `•\ _ %f—=, Other.monitoring according Sampling Obtain and analyze water samples from monitoring wells; as=`applicable, to Permit conditions, as per permit requirements. applicable. et.' ■ Report findings to DEH per permit regwrements. '�, According to permit ■ Standard report to include dates, observation ell.and monitoring'Woll conditions, typically every 1 Reporting readings and other data collected, work performed corrective actions to 2 years, depending on taken, and performance summary. ' 'f:- .. '� '77/ system size, usage, history, \ '/ - ■ Report publichealthlwater quality emergency,,to DEH; immediately. location. Onsite Systems Manual - Part 4 (9/2013) .Page 24 PRESSURE DISTRIBUTION TRENCHES & LATERAL SHUT-OFF/ADJUSTMENT VALVE (TYP.) SUPPLEMENTAL TREATMENT (OPTION) DIVERSION VALVE. SEPTIC TANK PUMP CHAMBER PVC PRESSURE LINE DISTRIBUTION MANIFOLD (TYP.) PRIMARY DISPOSAL FIELD - -0 -O -0 SECONDARY DISPOSAL FIELD -0 END RISER & FLUSH PORT (TYP.) SHALLOW PRESSURE DISTRIBUTION SYSTEM . SCHEMATIC FILTER FABRIC �lv SILT BARRIER i 12" MIN. TRENCH BACKF (NATIVE SOILS) 2" DRAIN ROCK ABOVE PIPE 0 08° cP 00 000 o & D o0 00 X000 .. ..- 0o0°ooOge °OQo of PRESSURE �00.0 ° D �° �° ®° °goo °O°a f DISTRIBUTION PIPE =SIDE ° ° woo 3/4" TO 1 1/2 DRAIN ROC UTILITY BOX - � v FILTER FABRIC 12" MIN, SILT BARRIER o 0080 goy40AC °o°Ocp° , o9. 3/4" TO 1 1/2" DRAIN ROCK g�D00 12" MIN. 18" TO 36" — I *12" WIDTH OK WITH SUPPLEMENTAL TREATMENT END VIEW TRENCH INSPECTION WELL W/ END CAP INSPECTION RISER, W/ THREADED END CAP FINISHED GRADE SWALLOW PRESSURE -DISTRIBUTION .SYSTEM GUIDELINES FOR MOUND SYSTEMS A. DESCRIPTION A mound: system consists of an elevated sand bed with a gravel distribution bed covered by soil fill. Mound systems are intended to raise the soil absorption system°'above grade and provide further 'treatment (sand filtration) of effluent before it reaches`:n e soils. It utilizes the shallow surface soils for broad distribution of effluent, and is used fomitigate high water table and shallow soil conditions on flat or gently sloping terrain. �Mound'`systems can be used -where there are at least two feet of permeable surface soils (ab ove'the water'=ta"ble or restrictive soils) '1 on slopes up to 20 percent, depending upon percolation"ch r cteristics. B. CONSTRAINTS ADDRESSED 1. High groundwater; t, 2. Shallow soil over fractured rock or coarse,,alluvium; 3. Shallow soil over impermeable soil or,bedrock, 4. Slow percolation at standard dispersal t'rench�depth ;and/ 5.- Limited disposalapea. C. SITE CRITERIA 1. Setbacks: Horizontal setback requiremer ts'for mound systems shall be those applicable to conventional disposal.fields, as s`pebfied in Santa Clara County Code section B11-67. 2 Vertical Separation Requirements. a. Depth to Groundwater. Minimum depth to seasonal high groundwater, as measuredlom ground surface, shall vary according to soil percolation- rate as"follows: tion Rate, MPI: Depth to Groundwater 1-5 3 feet 6-120 2 feet b. Soil Depth. Minimum depth.of soil, as measured from ground surface to impermeable soil or rock, for mound systems shall be 2 feet. This soil depth Onsite Systems Manual - Part 4 (9/2013) Page 25 requirement shall apply within the mound fill area and in the adjacent area extending a distance of 25 feet down-slope of the mound system. 3. Percolation Rate. Average percolation rate for mound systems shall be within the range of 1 to 120 minutes per inch (MPI), as determined from testing at a depth of 1 to 2 feet below ground surface. These percolation requirements shall apply within the mound fill area and in the adjacent area extending a distance of 25 feet down-slope of the mound system. Z\, 4. Ground Slope. Maximum ground slope for mound systems sh �l>be 20% where the percolation rate is in the range of 1 t660 MPI. For soils with a percolation rate greater than 60 MPI, maximum ground slope for mound systems'- '6a[F I be\15%. 5. Reserve Area/Dual System. A reserve area havingsuitable site conditions and sufficient area for full, 100% replacement of the primary, ' o`und shall be provided:or-a complete dual primary and secondary mound system. shall,be installed initially. See 4.9`for circumstances requiring the installation of a dual: system:(andapplicable requirements). In determining the necessary space for the primary,and,secondary mound, the required basal area (per D.8) of the primary -and secondary mound shall not overlap. The surplus sand run -out and soil fill may also not overlap unless the primary and secondary mounds ,, j� are installed together as a dual systems -o D. DESIGN CRITERIA.`` 1. Treatment. Them and system shall be preceded by a septic tank sized for the design sewage flowd'constructedin accordance with%requirements contained in Part 3 of this e in r Manual. 2. Desagn Sewage:Flow. The'Yriound system shall be designed on the basis of the projected swage flow -for the" structure or facility being served, determined in accordance with sewage flow estimation guidelines in Part 3 of this Manual. 3. Pressure Dosing. Septic tank effluent shall be applied to the mound system by pressure dosing, utilizing,a pumpsystem. The pressure distribution system shall be designed in accordance with accepted engineering practices to achieve, at a minimum: a. Unifo.rm'dosing of septic tank effluent over the surface application area of the mound distribution bed; b. Adequate flow rate, screening of effluent and suitable piping network to preclude solids accumulation in the pipes or clogging of discharge orifices; c. Suitable access provisions for inspection, testing and adjustment of the pressure distribution system; Onsite Systems Manual - Part 4 (9/2013) Page 26 d. Dosing volume to achieve a minimum of Ito 5 doses per day at design flow conditions; and e. At least one distribution lateral for every 36 inches of bed width. Additional requirements for design and construction of pressure distribution piping systems contained in "Guidelines for Pressure Distribution Systems" shall also apply. 4. Pump System. The pump:system shall be: (a) appropriate for sewage applications; (b) of !. 3, the size and type to meet the hydraulic design requirements, and (c) designed and constructed in accordance with pump system requirements'provided in Part 3 of this Manual. 5. Sand Fill. 4 'N e a. Sand Specifications. The sand media,,shall.:bbe,,a medium to coarse sand which meets the following gradation specifications: fr Sieve Size Percent Passing #4 90' I00\ #10 100 W � 152 —,11 '45:'82. . 257 55 #50 6; ' 5 � 42p \\#60 ,¢, _. O-'10/ 00:=-_ . _0 -'4 ## 0.0� ----:&O - 2 Documentation "4 material shall bE aboratory;sieve analysis results for the proposed sand fill pplied to DEH to verify conformance with the above sp.ecitications. b. Sand Depth. The minimum depth of sand fill, below the gravel distribution bed, shall be 12 inches. T,he minimum depth of sand fill shall be increased to 24 inches for sites where the'ave age percolation rate is between 1 and 5 MPI; such sites also require greater separation to groundwater below ground surface (3 feet rather than 2 feet). c. Lateral Dimensions. The sand shall be placed as a continuous fill extending in lateral dimensions as, necessary to meet the following minimum requirements: (1) Top of the sand fill shall extend horizontally beyond the gravel distribution bed: • 1 foot inthe upslope direction • 2 feet in the down-slope direction Onsite Systems Manual - Part 4 (9/2013) Page 27 • 2 feet in the longitudinal (side) direction (2) Maximum slope of the top -of the sand surface shall be 3 horizontal to 1 vertical. (3) Bottom of the sand fill shall be large enough to meet minimum mound sizing -requirements based upon basal area and linear loading rate criteria per D.8 below. 6. Gravel Distribution Bed ' a. Material. The distribution bed shall consist of 3/8` -inch double washed pea gravel, substantially free of fines. b. Depth. Pea gravel shall extend a minimurn,of 6 inches below the invert and 2 inches above the top of the distribution piping: c. Width. Maximum width of the distributioh;bed�sh SII be510 feet. r' d. Level. The bottom of the distribution bed shall,beNevel; and the down-slope side shall be parallel to the slopeNcontour. 7. Silt Barrier. The gravel distribution bed shall`.be Icovered in its ekirety with a geotextile ("filter fabric") silt barrier. Filter fabric shall either --be polyester, nylon or polypropylene, or any combination there -of, --and shall be sdita6lb for unilerdrain applications. Filter fabric shall be non-woven;`ssh`allnot act as a wicking agent and shall be permeable. S 8. Soil Cover. a. .Mate ari o A;continu.ous soil cover -shall be placed over the entire distribution bed J'and sand fill. The soil'cover shall consist of a medium, loamy -textured soil. b .Depth. Soil cover_depth shall`be a minimum of 12 inches and a maximum of 18 .inches over the top'of the'distribution bed, and 12 inches minimum over the sand fill portion of the mound. Soil cover over the distribution bed shall be crowned to. promote,rainfall runoff. c, Lateral YExtension. The soil cover shall extend a minimum of 4 feet beyond the perimeter edge of the sand fill in all directions. 9. Wastewater Application Rate. The wastewater application rates used for sizing the surface area of the distribution bed and the basal area of the sand fill shall be as follows: a. Distribution Bed. i (1) 1.2 gpd/ft for individual residential OWTS; and 2 (2) 1.0 gpd/ft for commercial, industrial, institutional and multi -residential. OWTS. Onsite Systems Manual - Part 4 (9/2013) Page 28 Reduction in the above wastewater loading rates or other provisions to insure the long-term integrity and performance of the mound distribution bed may be required. for high strength waste flows, such as from restaurants. b. Sand Basal Area. The basal area of the sand fill shall be sized to meet maximum basal wastewater application rates and linear loading requirements as follows: (1) Basal Wastewater Application Rates. • Effective Application Area. F ` ■ For level sites (0 2% slope) the effective basal wastewater application area includes the entti a sand fill basal area. ■ For sloping sites (>2% slope) flie effective basal wastewater application area includes -the sand basal area immediately low and directly down-slope (at right,angles to'the natural slope'contours) of the distribution bed.' • Wastewater Flow. ,The wastewater flow basal area shall be th design sewage flc •_ Application Rates. Theh -the demonstrated perco depth}as shown in Table TableM-4. -4 Basal 2 appli for determining sizing the -the system. :kion rate shall be based on ler 12 to 24 inches of soil ter Application Rates' Percolation Rate ? / Wastewater Application Rate (gpd/ft2) x.:'1;5 1.2 1.2 X24 1.2 30 1.12 . 45 0.68. 60 0.53 90 0.25 91-120. 0.2 1 Interpolate between reference values for other percolation rates; see end of Part 4 for expanded table listing interpolated values. Onsite Systems Manual - Part 4 (9/2013) Page 29 (2) Linear Loading. Requirements a Linear Loading Rate Definition. Linear loading rate is defined as the volume of wastewater flow (in gpd) divided by the effective length of the disposal system measured along the slope contour. Effective Length. The effective length (L) of the mound system for determining the linear loading rate shall be the length of the gravel distribution bed along the down-slope edge. Separate linear loading rate calculations shall be made for the primary and se onda.ry (reserve) systems. The effective length of each mound may overlap for purposes of determining compliance with linear loading rate criteria, since only one system would be in operation at a given time. Wastewater Flow. The wastewater,flo sed for determining the linear loading rate shall be as follows: ■ 100 gpd/bedroom for residential systems; ! ■ Design sewage flow rate for commercial, institutional, industrial and multi-residentiai'systems. Loading Rate Criteria. Mp.fm m linear loading rate for mound systems vary according to ground slope, and percolation rate4indicated in Table M-2. If a variance -from these crite`na,isp`roposed, it,must be supported by detailed groundwater, mounding analysis carried o`u in accordance with accepted methodology an' /or scientificNreferences dealing with water movement in soisand, utilizing site specific hydraulic conductivity (permeability) data. - Table.M_ -2.: -Maximum Linear Loading Rates s(gpd/lineal foot) Soil Depth•, Ground,Slope Percolation Rate (MPI) 1-30 31-60 61-120 0=10 5: 4 3 2 to 2.5 - 0-10 7 6 5 2:5 -to 3.0 11=20 8 7 6 . to/4.0 0-10 9 8 7 3.0 11-20 10 9:..: 8 0-10 11 10 9 > 4.0 11-20' . 12 z 11 Onsite Systems Manual - Part 4 (9/2013) Page 30 9. Dual Mound Systems. a. Dual System Requirement. Dual mound systems shall be required for any system where, due to space constraints, the sand fill run -out of the primary mound overlaps the sand fill run -out area of the secondary mound. b. Distribution Bed Placement. Dual mound systems shall have at least two distinctly separate distribution beds. The beds may be placed within one continuous mound or in separate mounds. The distribution beds may be placed end-to-end or upslope/down-slope of one another subject to meeting minimum sizing requirements for basal and linear loading rates per D.§.b bove C. Distribution Bed Separation. The minimum lateral (i a ,,end,to-end) separation between distribution beds in a dual mound system„shall be siX,feet. d. Effective Basal Area. For dual mound systems-the:.effective basal:"area for sizing the two systems shall not overlap. e.Alternate Dosing. The distribution beds fo"r`dual mound systems shall`fjeldesigned and operated to provide alternate dosing and resting ofthe beds. r°1 w 4� 10. Inspection Wells. A minimum of six"kinspection wells shall,estalled within and around mound systems as follows: a. One shall. be located near the center of th'e-mound, extending from the mound surface to the bottom of the gravel'.distribution bed: b. One shall be'locate&within the effective basal area (outside of the distribution bed), extending from the mound surface to 6`inches into the native soil. c. Four shall be locatedrespectively, midway along each of the four sides of the mound; -near the toe of the slope, -extending from ground surface to a depth of 5 r, -feet or t.&the'depth of:impermeable materials, whichever is less. �` d�\Inspection wells shall be constructed of 2" to 4” diameter pipe, equipped with a �wr\ench-tight cap, or, pipe plug and a bottom cap. All wells shall be perforated beginning at a depth.of 18 inches below grade and extending to the bottom of the pipe , Perforations shall consist of hacksaw slots at nominal 1" spacing, or equivalent commercially -slotted pipe. To prevent surface water infiltration, inspection wells shall be sealed:with a bentonite or concrete annular seal (or equivalent) to a depth of 12 inches; minimum. E. ENGINEERING PLANS AND CONSTRUCTION 1. Reference Guidelines. Construction of mound systems shall be in accordance with guidelines contained in the following references: Onsite Systems Manual - Part 4 (9/2013) Page 31 a. "Design and Construction Manual for Wisconsin Mounds", Small Scale Waste Management Project, University.of Wisconsin, Madison, January 2000, including any amendments. b. "Onsite Wastewater Treatment Systems Manual", U.S. Environmental Protection Agency, February 2002. 2. Engineering Plans. Engineering plans for shallow PD systems shall include: a: All relevant elevation data and hydraulic calculations, j: b. Specific step-by-step construction guidelines and notes for,�use by the installer; C.: Erosion control plan; d. Recommended make and model of all compo,n6ks; e. Recommended pump system components, with cut -sheet depicti`rig_float settings; f. Control panel programming; and r g. An inspection schedule listing critical control points. 3. Construction Inspection. Ata minimum, inspection of;4the.mound system installation should include the following. Joint kinspection by the d signer -,-contractor, and DEH may be required._ • Pre -construction inspection where`the c nstruction'staking or marking of the mound ed and'construction'p�rocedures discussed; system is prr6id i Water tightness of septic -tank and dosing•( ump) tank,- 4 ank; s. �► Clearing:,and ripping/plowing of tliewmound basal area soils; i°«', z� (Sand materia e Pea gravel distribiiti,on bed and piping installation; i o Hydraulic test of the distribution system; i Functioning and setting of all control devices; r . Placement of filter fabric silt barrier and soil cover; Final Inspection to verify that all construction elements. are in conformance with the approved plans and specifications, all inspection wells are installed; and erosion control has been completed. Onsite Systems Manual - Part 4 (9/2013) Page 32 F. MANAGEMENT REQUIREMENTS. Recommended minimum _procedures and frequency for inspection, maintenance, monitoring and reporting activities for mound systems are outlined in Table M-3 below. Table M-3. Mound Svstem Management Reauirements Onsite Systems Manual - Part 4 (9/2013) Page 33 Work ` > Frequency Inspection Conduct routine visual observations of mound and downslope `area Every 6 to 12 months. and surroundings for wet areas, pipe leaks or.damage soilaerosion,' drainage issues, abnormal vegetation; gophers or other problems. ■ Perform all inspections of pump and appurtenances (see Guidelines , '- for Dosing Pump Systems). #`r' Record observations:` Maintenance ■ Purge laterals, squirt and balance. ,._ Distribution system ■ Exercise valves to ensure functionality` ,,, :' maintenance annually. ■ Perform all maintenance work as recommended by equipment ' _" Other maintenance as required. manufacturer for any special valves orother components. j ■ Maintain mound area landscape vegetation, as req'd^ ■ Investigate and repair�rosion, drainage or`other disposal field problems,u n eded { ■ Investigatb,and perfor6dis ork bution:system rrective w, as req!d itr j ■ Record work„done `e Water ■ Measure and record water levels obserrvatiofi wells in distribution Measure mound system water Monitoring.& beds, sand.fillll and around mound—perimeter,,” levels annually. Sampling ; Obtain,6nd analyze water,samples from monitoring wells, as Other monitoring according to applicable; per permit requirements> permit conditions, as ��" ` ` -✓ applicable. Reporting Report findings to [)EH per permit requirements. According to permit conditions, .:; _ t ' ,L Standard report to include dates, observation well and monitoring icalf eve 1 to 2 ears, tYP y every y k'welf7eadings and.`other data collected, work performed, corrective depending on system size, actions.taken,and performance summary. usage, history, location. ■ Repoft p -131—health/water quality emergency to DEH immediately. Onsite Systems Manual - Part 4 (9/2013) Page 33 FLOW LINE t' FILTER INLET OUTLET COMPARTMENT , COMPARTMENT 2/3 SEPTIC TANK js 1/3 SEPTIGTANK SEPTIC TANK PUMP CHAMBER MOUND DISPERSAL FIELD T --GRAVEL BED t� - r� �vM •'iw. �t ��+,_66s'^`��ii.�trr:' {t rs]�: ra�.W'a aC•x'" `r,: ��. —'unR _�_murvN�r�? ,Nin GROUNDWATER TABLE DIAGRAM OF A MOUND SYSTEM 1— GRAVEL DISTRIBUTION BED PRESSURE DISTRIBUTION LAT ERALS(TYP.) SHUT-OFF VALVE 0 PVC PRESSURE LINE FROM DOSING PUMP 1 SOIL COVER SAND FILL; ENTIRE SAND BASAL -�- AREA USED FOR SYSTEM SIZING INSPECTION WELL (TYP.) 4' MIN: INSPECTION/ CLEANOUT RISER (TYP.) MOUND SYSTEM SCHEMATIC LEVEL SITE GRAVEL DISTRIBUTION BED UTILITY BOX (TYP.) FILTER FABRIC INSPECTION/ TOPSOIL COVER CLEANOUT RISER (TYP.) MULCHED OR PLANTED TO INSPECTION WELL (TYP.) NATIVE GRASSES 18" FOLLOWING CONSTRUCTION MEDIUM SAND FILL1 11 10, (TYP.) -:; {� ^' 12" MIN. ,d;• ;rim: .:i{4h,`=: ••�:n'F.ry;:.. �..: 1A111111111111111.i. 1111 l I II " I I ' pll� 111111. II III► �� ..: PLOUGH OR RIP NATIVE --' SURFACE SOILS PRIOR TO SAND PLACEMENT TYP.) 2 ( p10, (TYP.) 11 MIN 111 w, I W MIN. (TYP.) PRESSURE DISTRIBUTION PIPING PRESSURE LINE FROM DOSING PUMP MOUND SYSTEM CROSS-SECTION LEVEL SITE r GRAVEL DISTRIBUTION BED SLOPE SOIL COVER PRESSURE DISTRIBUTION LATERALS (TYP.) SHUT-OFF VALVE (TYP.) PVC PRESSURE LINE '• ' F' � !" , FROM DOSING PUMP IN INSPECTION WELL (TYP.) 4' MIN. SAND FILL _ INSPECTION/ CLEANOUT RISER (TYP.) BASAL AREA FOR SYSTEM SIZING MOUND SYSTEM SCHEMATIC SLOPING SITE GRAVEL DISTRIBUTION BED TOPSOIL COVER; MULCHED OR PLANTED TO NATIVE GRASSES FOLLOWING CONSTRUCTION 10' (TYP.) + 3 lq* 1 -195 UTILITY BOX (TYP.) FILTER FABRIC INSPECTION/ CLEANOUT RISER (TYP.) a� r— MEDIUM SAND FILL 3. . •. Route �� _�.��Y;:•�' ao � 2 111111 II II u,f I �AIllh�uu I III I I . � 1! `�4'^�• .....+.,... PRESSURE DISTRIBUTION PIPING PRESSURE LINE FROM DOSING PUMP PLOUGH OR RIP NATIVE SURFACE SOILS PRIOR TO SAND PLACEMENT INSPECTION WELL / (TYP.) 10' 3 (TYP.) �- �1 1 4 % 4140 11 11111 _ 4' MIN. (TYP.) -� MOUND SYSTEM CROSS-SECTION SLOPING SITE GUIDELINES FOR AT -GRADE SYSTEMS A. DESCRIPTION At -grade systems are similar to mound systems, except that they, do not include the sand bed; the gravel distribution bed is placed directly on the scarified (i.e., plowed) soil.surface. They are often used in conjunction with a supplemental treatment sys#em..,They can be used in the same types of situations as mound systems to overcome shallow soil depths and high groundwater. B. CONSTRAINTS ADDRESSED ��µh 1. High groundwater; L� 2. Shallow soil over impermeable soil or bedrock, Y ,> 3. Shallow soil over fractured rock or coarse alluvium;ad�' 4. Limited dispersal area.ii % a C. SITE CRITERIA 1. Setbacks. Horizontal setback requirements,for At ad gre;systems shall be those applicable to conventional. dispersal fields as specifi6d1n Santa Clara .County Code section B11 67°° 2. Vertical Sepa tiowRequirements. 4 a ,-Depth.to Groundwater:` Vlinirrrum'depth to seasonal high groundwater for At- grMeasy tems, aszm`easured from ground surface, shall vary according to soil 1,1,117 percolation rate and tho leuel of treatment provided as shown in Table AG -1. b`\ Soil Depth IVlinimum,,depth of soil, as measured from ground surface to *,impermeable Soil or rock, for At -grade systems shall vary according to soil 'percolation rate' and the level of treatment provided as shown in Table AG -1. These soil depth requirements shall apply within the dispersal field and in the adjacerit area extending a distance of 25 feet down-slope of the At -grade system on sloping sites, and a distance of 15 feet on all sides on level sites. Onsite Systems Manual - Part 4 (9/2013) Page 34 Table AG -1 Minimum Vertical Separation Requirements for At -grade System (feet, below ground surface). Percolation Rate (MPI.) Depth to Groundwater Soil Depth Primary Supplemental Treatment* . Treatment** Primary Treatment* Supplemental Treatment** 1-5 5 3 3 2 6-60 3 2 ,3 2 61-120 NA*** 2 NA***`� 2 . * Provided by aseptic tank sized and constructed in accordant this Manual.>' ** Provided by an approved alternative treatment system idem ***Supplemental treatment required where percolation' ate is 3. Percolation Rate. Average percolation rate fo At -grade range of 1 to 120 minutes per inch (MPI),�ascl termined' depth below ground surface. Where the percolation rat MPI supplemental treatment shall be required. These,p apply within the dispersal field and,in the adjacent a ea' down-slope of the At -grade system o sloping sites, and On level sites. 4. Ground Slope. Maximum ground sib r•r NA reserve area having suitable site conditions and sufficient rent of the primary At -grade system shall be provided or a secondary At grade system shall be installed initially. See ring' he instaliz tion of a dual system (and applicable ing the note sary space for the primary and secondary gravel distribution bed area (per D.4) of the primary. and rlap. The surplus soil fill run -out may also not overlap )nada y At -grades are both installed (i.e., as a dual system). 5. Reserve Area/Dual Syst area for full: "'o re la complete dual primary DJ for circumstances rE f., (reserve field, the requh f < 1 secondary At -grade shall unless,the primary and`si -A. with requirements in Part 3 of Manual 60 MPI. systems shalhbe*within the from testing at 2-,' 'to -3 feet e is -in the range o 60 to 120 ercolation requirements shall extending a distance of 2S feet a distance of 15 feet on all sides ms shall be 20%. D. DESIGN CRITERIA,!4tr 1. Treatment. The'following treatment requirements shall apply in connection with the use of At -grade systems: a. Primary (septic tank) treatment shall be the minimum level of treatment, and shall be acceptable where the average percolation rate is in the range of 1 to 60 MPI and the applicable vertical separation distances are met per Table AG=1. b. Supplemental treatment, using an approved alternative treatment system identified in this Manual, shall be required where the average percolation rate is Onsite Systems Manual - Part 4 (9/2013) Page 35 between 61 to 120 MPI, and/or to allow compliance with reduced vertical separation distances as provided in Table AG -1. 2. Design Sewage Flow. At -grade systems shall be designed on the basis of the projected sewage flow for the structure or facility being served, determined in accordance with sewage flow estimation guidelines in Part 3 of this Manual. 3. Pressure Dosing. Wastewater effluent, from the septic tank or supplemental treatment system, shall be.applied to the At -grade system by pressure dosing, utilizing a pump system. The pressure distribution system shall be designed;` accordance with accepted engineering practices to achieve, at a minimum:'` £4 a. Uniform dosing of effluent over the surface,,,. li. ation aaof the At -grade distribution bed; , b. Adequate flow. rate, screening of,effluent and suitable piping networkrto preclude solids accumulation in the pipes.or clggging,of dischargeyorifices; c. Suitable access provisions for inspection, testing and adjustment of the pressure distribution system;Ik d. Dosing volume to achieve a minimumfof 3 to 5 -dos s per day at design flow conditions.'and'�,,� �.,•, �`;�' IP e. At least one�distribput on lateral forsevery 36 inches of distribution bed width. Additional -requirements for design a d,construction of pressure distribution piping systems costa ed;in "Guid'el,ines for. Pressure Distribution Systems" shall also apply. NI - 4'' --Pump System. The pump system shall be: (a) appropriate for sewage applications; (b) ohhe'size and type to: meet the hydraulic design requirements; and (c) designed and constructed in accordance with pump system requirements. provided in Part 3 of this i� Manual. S. Gravel Distribu;rtion Bed a. Material. -The distribution bed shall consist of 3/8 -inch double -washed pea gravel, substantially free of fines. b. Depth. Pea gravel shall extend a minimum of 6 inches below the invert and 2 inches above the top of the distribution piping. c. Width. Maximum width of the distribution bed shall be 10 feet. Long, narrow distribution bed configurations are preferred. Onsite Systems Manual - Part 4 (9/2013) Page 36 d. Wastewater Application Rate. The wastewater application rate used for sizing the basal surface area of the distribution bed (i.e., soil infiltrative surface) shall vary according to the soil percolation rate of the native soil and the level of wastewater treatment provided as indicated in Table AG -2. Table AG -2. Wastewater Application Rates for At -grade System" Percolation Rate Septic Tank Supplemental Treatment (MPI) Treatment Standard Rate Standard -" �' Enhanced Treatment (gpd/ftz) Rate 21 Rate Multiplier4 (gpd/ftz){ , (gpd/ftp) 1-5 1.2 0 , 10 0.8 ; 0:8~\, �. 1:2 1:5 24 0.60 ' 0.60 1.2 '--,- ,\ ....._ ' -2.0- . 30 0.56 f._ 0.56 ' 1.12. 12.0 45 0.45 0.,45 ^,' -- ..� 0.68 _�'•� :,1.5- :1.5_60 60 0.35 0.35'x'` 0.53 "_ 1.5 90 NA 0.2O._ NA ": NA 91-120 NA ''` , , 0.20 `., -`, NA ; NA "Interpolate between reference values.-for-,other�percolation rates;;te64nd of Part 4 an expanded table listing interpolated values. �,° 2 Applies where supplemental treatmenij used -i -conne'ction..wifh reduced depth to groundwater, reduced soil depth,:or-for, mitigation of other.site constraint 3Applies where.standard ver tical separation distances are�met. a For reference only. Reduction in the above wastewater loading rates or other provisions to insure the long-term integrityand performance -,6f the.At-grade distribution bed may be ,Jecl ired,for high strength waste flows, such as from restaurants. e. ``Minimum Basal Area Sizing jAt a minimum, sizing of the distribution bed basal area �`'.'sliall be determined,.by dividing the design wastewater flow (in gpd) by the applicable wastewater application rate per Table AG -2. L C Linear1L ceding Rate Requirements. The length of the distribution bed shall be sized to meet m ximum linear loading rate criteria as follows: (1) Linear Loading Rate Definition. Linear loading rate is defined as the volume of. wastewater flow (in gpd) divided by the effective length of the dispersal system measured along the slope contour. (2) Effective Length. The effective length (L) of the At -grade system for determining the linear loading rate shall be the length of the gravel distribution bed measured along the down-slope edge. Separate linear loading rate calculations shall be made for the primary and secondary Onsite Systems Manual - Part 4 (9/2013) Page 37 (reserve) systems; however, the effective length of each field may overlap for purposes of determining compliance with linear loading rate criteria. (3) Wastewater Flow. The Wastewater flow used for determining the linear loading rate shall be as follows: o 100 gpd/bedroom for residential systems; Design sewage flow rate for commercial, institutional, industrial and multi -residential systems. Nab (4) Loading Rate Criteria. Maximum linear load vary according to ground slope and percolai 3. If a variance from these criteria is propo. .detailed groundwater mounding an.alysis`ca X accepted methodology and/or scientific ref( movement in soils and utilizine=site specific Table AG -3. eDd/I ng rates for At -grade systems on rate -as indicated in Table AG - ed, it must be supported by ried out in' c66rdance with rences dealing�with water vdraulic conductivity data. Rates* Soil Depth Ground Slop'er,,,, Percolation Rate (MPI) (ft) (%) 1-30 317jsb 61-120 0-10 `' t 5a �4 3 , 2.0 to 3.0 11 20' `6 "' 5 4 v: 0-107 �` ; ° 6 5 3.0 to 4 0 40-to50 ` 20 is 10 9 0 10 11 10 9 77,—>5, 0 11 20 14 6 Silt'Barrier. The gravei"distribution bed shall be covered in its entirety with a geotextile ("filter fabric") silt barrier! Filter fabric shall either be polyester, nylon or polypropylene, or any combination thereof; and shall be suitable for underdrain applications. Filter fabric shall be non woven, shall not act as a wicking agent and shall be permeable. 7. Soil Cover a. Material. A continuous soil cover shall be placed over the entire distribution -bed. The soil cover shall consist of a medium, loamy -textured soil. b. Depth. Soil cover depth shall be a minimum of 12 inches and a maximum of 18 inches over the top of the distribution bed. Soil cover=over the distribution bed shall be crowned to promote rainfall runoff. c:. Lateral Extension. The soil cover shall extend a minimum of 4 feet beyond the perimeter edge of the gravel bed in the upslope and sideslope directions. In the Onsite Systems Manual - Part 4 (9/2013) Page 38 down-slope direction, the soil cover extension beyond the down-slope edge of the gravel bed shall vary accordingao slope as follows: Ground Slope N Soil Fill Extension (ft) 0-2 4 3-4 6 5-6 8 7-8 10 9710. 12 11-12 14 f 13-14 16 -' 15-16 18 17-20 20 8. Dual At-Grade Systems a. Dual System Requirement. Dual At-gi` de systems s all be required for any system where, due to space constraints, the soil cover run`o t df the primary�t-grade overlaps the soil cover run-out area of the secondary At-grade. b. Distribution Bed Placement4'Dual-At-grade systems s all have at least two distinctly separate distribution beds. The4b`eds ay.be placed with one continuous soil cover fill or with independent soil coverfill The distribution, beds may be placed end-to- end or upslope/down-slope of one another, subject-to meeting minimum sizing requirementsdetermined from basal area and lire r loading criteria per D.5(f) above eaA 'A c. Distributio+.cn Bed,Separation. The minimurri'lateral (i.e., end-to-end) separation between distributioriSeds for -dual At-grade systems shall be six feet. Cl. Afiteinat6Zbsing. The distribution-beds.for At-grade systems shall be designed and operated to�provide alternate dosing and resting of the beds. 9 <Inspection Wells. A minimum of;fh ee (3) inspection wells shall be installed within and around1At`grade systemsas follows: a. One shall be located near the center of the At-grade system, extending from the fill surfaceAto the bottom of the gravel distribution bed. b. One shall b6,16cated 5 to 10 feet upslope of the At-grade system, midway along the length of the At-grade, extending from the ground surface to a depth of 5 feet or to contact with an impermeable substratum, whichever is less. c. One shall be located midway along the down-slope length of the At-grade, within 5 to 10 feet from the toe of the fill slope, extending from ground surface to a depth of 5 feet or to contact with an impermeable substratum, whichever is less. d. Inspection wells shall be constructed of 2" to 4" diameter pipe, equipped with a wrench-tight cap or pipe plug and a bottom..cap. All wells shall be perforated Onsite Systems Manual - Part 4 (9/2013) Page 39 beginning at a depth, of 18 inches below grade and extending to the bottom of the pipe. Perforations shall consist of hacksaw slots at nominal.1" spacing, or equivalent commercially -slotted pipe. To prevent surface water infiltration, inspection wells shall be sealed with a bentonite or concrete annular seal (or equivalent), extending from the ground surface to depth of 12 inches, minimum. E. ENGINEERING PLANS AND CONSTRUCTION A 1. Reference Guidelines. Construction of At -grade systems shall, be in a eordance with guidelines contained in the following references:. a.. "Wisconsin At -grade Soil Absorption System Siting "Design an'd1tonstruction Manual", Small Scale Waste Management Project, University of Wisconsin=Madison, 1990. b. "Onsite Wastewater Treatment Systems Manual", USS. Environmental Protection Agency, February 2002. 4 c. "At -grade Component Using Pressure Distribut!on,Ma al'for Private O' site Wastewater Treatment Systems", State of Wisconsin, Department of Commerce, 1999.` 2. -Engineering Plans. Engineering plansfo`rsliallow PD systems shall include: a. All relevant elevation data and by raulie cal ulations � b. Specific step,by=step construction gUitlelines andrnotes for use by the installer; C. Erosion control,plan- , d. Recommendedmake and model of all components; e Recommended pum s stem cments, with cut -sheet depicting float settings; f. Control panel programming; and g An inspection schedule listing critical control. points. 3. Construction\Inspection.At a minimum, inspection of the at -grade system installation should includebe`following+:Joint inspection by the designer, contractor, and DEH may required. p, + Pre -construction inspection where the construction staking or marking of the at - grade system is provided and construction procedures discussed; + Water tightness of septic tank and dosing (pump) tank; + Clearing and ripping/plowing of the at -grade basal area soils; to Pea gravel distribution bed and piping installation; Onsite Systems Manual - Part 4 (9/2013) Page 40 Hydraulic ("squirt") test of the distribution system; Functioning and setting of all control devices; Placement of filter fabric silt barrier and soil cover; Final Inspection to verify that all construction elements are in conformance with the approved plans and specifications, all inspection wells are installed; and erosion control has been completed. F. MANAGEMENT REQUIREMENTS' ' Recommended minimum procedures and .frequency fp inspection, maintenance,`monitoring and reporting activities for At -grade systems are outlined in"Table AG -4 Table AG -4. At -grade Svstem ManagementRe`auirements yl F_ Work Frequency Inspection Conduct routine visual observations of APGrade fill and downslope X.Every 6 to 12 months. area and surroundings for wet areas; pipe,leak 'or damage, soil �4 r erosion, drainage issues, abnormal vegetation;-gophe .or other problems. '4i M" ■ Perform all inspections of pump and appurtenances (see Guidelines for Dosing,Pump Systems). ■ Record''observations Maintenance Purge laterals; squirt and.iialance )..r Distribution system ._-Exercise valves to ensu�r,.e functionality maintenance annually. �, —Perfor all�maintenance work as recommended by equipment Other maintenance as required. ;v manufacturer for any specialvalves or other components. * Maintain fillar6a fandscape vegetation, as applicable and as needed. 1■ Investigate and repair erosion; drainage or other disposal field °lproblems, as needed: �`S Oestigate and distribution system corrective work, as perform needed. ■ Record;w11, P; ork.done. Water ■ Measureard record water levels in observation wells in distribution ■ Measure dispersal system Monitoring & bed:and round system perimeter. water levels annually. Sampling ■ Obtain and analyze water samples from monitoring wells, as ■ Other monitoring according to applicable, per permit requirements. permit conditions, as applicable. Reporting ■ Report, findings to DEH per permit requirements. - ■ According to permit conditions, ■ Standard report to include dates, observation and monitoring well typically every 1 to 2 years, readings and other data collected, work performed, corrective depending on system size, actions taken, and performance summary. usage, history, location. ■ Report public health/water quality emergency to DEH. immediately. Onsite Systems Manual - Part 4 (9/2013) Page 41 SUPPLEMENTAL TREATMENT (OPTION) SEI INSPECTION WELL (TYP.) AT -GRADE SYSTEM SCHEMATIC UTILITY BOX (TYP.) DISTRIBUTION BED; DOUBLE WASHED PEA GRAVEL MULCHED OR PLANTED WITH NATIVE GRASSES FOLLOWING CONSTRUCTION —� EXISTING GRADE ,yam" ft,mm M=41 DISTRIBUTION MANIFOLD AND.LATERALS BASAL AREA J NATIVE SURFACE SOIL; FOR SYSTEM SIZING STRIP VEGETATION AND PLOUGH OR RIP PRIOR. TO. - PRESSURE LINE FROM GRAVEL AND SOIL DOSING PUMP PLACEMENT 0 . o s INSPECTION RISER W/ THREADED END CAP TYP. FILTER FABRIC SILT BARRIER INSPECTION WELL (TYP.) r— TOPSOIL COVER `SLOPE --� 10'TYP.-----�I AT -GRADE SYSTEM CROSS-SECTION GUIDELINES FOR PRESSURE -DOSED SAND TRENCH SYSTEMS I_101074.11]1q, iilleP Pressure -dosed sand trench (PDST) systems are a variation of a shallow pressure distribution system that utilizes a medium -grade sand in place of a portion of;``tfe gravel backfill in the dispersal trench, to improve treatment of effluent and-normalize,tF a flow of effluent before it reaches the trench bottom. Treatment occurring in the sand;af ll.cap enhance the acceptance rate of native soils beneath the trench. This type of design can}also`be'used with supplemental treatment, and Js well suited for conditions where underlying'•soils are'highl_y permeable and/or groundwater beneath a system is especially'vuInera b'le,to wastewater contaminants. f t l VINtw B. CONSTRAINTS ADDRESSED'. 1. High groundwater; andti 2. Rapid percolation. C. SITE CRITERIA` a 1. Setbacks. Horizontal -setback requirementsfor shallow,PDST systems shall be those applicable to conventional dispersal fields, as specified in Santa Clara County Code \ section B11-67 , 3 2. Vertical Separation Requirements.!' ,.'�.w-a l.Depth„to Groundwater Minimum depth to seasonal high groundwater for PDST systems, as.measured from trench bottom, shall vary according to soil percolation rate, leveliof treatment provided, and sand fill thickness as shown in ;Table PDST 1. r,Soil Depth' :Minimum depth of soil, as measured from ground surface to \' impermeaEle soil or rock; for PDST systems shall be 2 feet. Table PDST-;1 Minimum Groundwater Separation Requirements for Shallow PD System (feet, below sand -soil interface) Percolation Rate Depth to Groundwater (MPI) Primary Treatment - Supplemental Treatment 1-5 31 22 6-120 22 23 1 , c'ruiui nanu uuLMlt:bb 2 12 -inch sand thickness 36 -inch sand thickness Onsite Systems Manual - Part 4 (9/2013) Page 42 3. Percolation Rate. Average percolation rate for PDST systems shall be within the range of 1 to 120 minutes per inch (MPI); as determined in accordance with standard percolation requirements for conventional dispersal trenches. 4. Ground Slope. a) Maximum ground slope in areas used for shallow PDST systems shall be 40 percent. f b) Any PDST system located on slopes greater,tharr-26'p�ercent shall require the completion of a geotechnical report and slope stability,analysis as specified in Santa Clara County Code section 1311-83 - 5. Dual System. Per Santa Clara County Code' section 131126' d), two PDST`-dispersal fields, each one hundred percent of the total size required for`the design.sewag6,flow, shall be . installed and interconnected with an approved flow diversion device (pressure -rated), intended to allow alternate use of -the two fields. D. DESIGN CRITERIA 1. Treatment. The following treatment,requi-rements_shall=apply in connection with the use of PDST systems-!- a. Primary (septic tank) treatment shallbe the minimum level of treatment, and shall be acceptable`where the�applicable verticafseparation distances are met per Table PDST-1. b:1� Supple eh:tal`tr•eatm'ent using an approved alternative -treatment system identified in this Manual, may be used-to%allow compliance with reduced vertical separation ` distances as provided inTable PDST-1. 2. Design Sewage Flow:,PDST systems shall be designed on the basis of the projected sewage flow.,f& the structure or facility being served, determined in accordance with 711 sewage flow estimation guidelines in Part 3 of this Manual. 3. Pressure Dos g Septic tank effluent shall be applied to the PDST system by pressure dosing, utilizing either an automatic dosing siphon or pump system. The pressure distribution system shall be designed in accordance with accepted engineering practices to achieve, at a minimum: a. Uniform dosing of septic tank effluent throughout the system of PDST trenches; b. Adequate flow rate, screening of effluent and suitable piping network to preclude solids accumulation in the pipes or clogging of discharge orifices; Onsite Systems Manual - Part 4 (9/2013) Page 43 c. Suitable access provisions for inspection, testing and adjustment of the pressure d istribution system; and d. Dosing volume to achieve minimum of 3 to 5 doses per day at design flow conditions. Additional requirements for design and construction of pressure distribution piping systems contained in "Guidelines for Pressure Distribution Systems" shall also apply. 4. Pump System. The pump system shall be: (a) appropriate for sewage 'applications; (b) of the size and type to meet the hydraulic design requirements;.and'�(c) designed and constructed in accordance with pump system requirements provided in Part 3 of this Manual.' ' 1 S. Drainfield Trenches. PDST drainfield trenches shall conform t&the°same design and construction requirements as shallow RD trenches,,perthiskManual, with the exception that the trench filter material (below the distribution•,pipe) shall consist of a minimum of 6 inches of double -washed pea gravel underlaitn'by 6,to 24 inches of medium sandjill, per Table PDST-1 and paragraph D.7.b. r' 6. Trench Width. Trench widths for PDST systems be,ps``follows: a. For septic tank effluent:-` 1g``to 36 inches "':N'. =: V\ ..' ' b. With supplemental treatment �` �" 12 to 36,inches 7. Sand Fill. ,. A. - °� a.'Sand Specifications. The sand media shall,be a medium to coarse sand that meets the following gradatioWspecifications �; ' Sieve, Size ` Percent Passing - 3/8 .' `:' 100 90-100 )-i 62-100 \k6 45-82 #30 25-55 2#50 5-20 #100 0-4 #200 0-2 Documentation of laboratory sieve analysis results for the proposed sand fill material shall be supplied to DEH to verify conformance with the above specifications. b. Depth of Sand. The minimum depth of sand below the drain rock shall be as follows: i. For septic tank effluent: Onsite Systems Manual - Part 4 (9/2013) Page 44 8 1-5 MPI percolation: 24" * 6-120 MPI percolation: 12" ii. With supplemental treatment: * 175 MPI percolation: 12" * 6-120 MPI percolation: 6" Wastewater Application Rates. Wastewater application rates used for, system sizing shall include consideration of both the:a ()pea gravel -sand interface; and (b) sand -soil interface, bottom area only. The more restrictive criterion'shall govern system sizing. a. Pea Gravel - Sand Interface. The wastewater.<applicat on, rate used for sizing the pea gravel -sand interface shall be: is 1.2 gpd/ft for individual residential OWTS. ii. 1.0 gpd/ft for commercial, industrial, institutional and multi -residential OWTS. b. Sand - Soil Interface. The.wastewater application,,rate for sizing the sand -soil interface (considering bottom -a er a. only) shall be ba e-d;upon representative percolation test results for the soil zone cor-respondin`g with trench bottom depth as shown in Table PDST Tabl:!P66§T-2. Wastewater Application Rates .Percolaiion Rate 4 ` Wastewater Loading . (MPI)`_- ' r Rate ` - (gPd/ft2) ,N � `1-5 1.2 `10 1.2 . �t 24'' 1.2 30 1.12 45 0.68 60 0.53 90 0.25 91-120 0.2 1 interpolate between reference values for other percolation. rates; see end of Part 4 an expanded table listing interpolated values. Reduction in the above wastewater loading rates or other provisions to insure the long-term integrity and performance of the PDST trenches may be required for high strength waste flows, such as from restaurants. Onsite Systems Manual - Part 4 (9/2013) Page 45 9. Trench Sizing. The required square footage of trench infiltrative surface shall be calculated based on the design flow and the applicable wastewater application rates:per paragraphs 8a and 8b. The required length of trench shall be calculated based on the bottom area only, up to a maximum.of 3 square feet of effective infiltrative surface per lineal foot of trench. 10. Inspection Wells. A minimum of three (3) inspection wells shall be installed within and around PDST systems for the purpose of checking groundwater levels periodically, and may also be used for water quality sampling, as needed. Inspection wells shall extend to a depth of 3 feet below the bottom of the PDST trenches or to contact -with impermeable materials, whichever is less. The inspection wells shall be located and constructed as fnIInmis , a, One shall be located upslope of the dispersal field,"" as a background or control well; b. One shall be located within the dispersal field, typic center of the field; c. One shall be located down-slope of the dispei-sal"fiE horizontally from the lowest tr nch(es), and p sitic point for monitoring -the area "estimated to be in the percolating wastewater; d. Inspection wells shall be constructed of wrench -tight cap -or: pipe plug and a bot beginning at,a-depth,of 18 inches below pipe. Perforations shall consist of hacks commercially- otted pipe. To prevent shall be sealed Wion th,abenfite-or:.,con,c :..N, pically'10 to,1` �L ly between trE away, to serve earthe Id, typically 10 to 25 feet led to provide a representative probable flow path of t&.4"'diameter pipe, equipped with a om cap 'A,11'wells shall be perforated grade and extending to the bottom of the 3w slots at nominal 1" spacing, or equivalent urface water infiltration, inspection Wells ete annular seal (or equivalent) to a depth 11 Trench Inspection Wells A minimum of two (2) inspection wells shall be installed within reach -trench for the `purpose of checking ponded water levels periodically. One well shall extend to the trench b`ottoFn, and a second well shall extend to pea gravel -sand fill interface.- The trench inspection -wells shall preferably be located at the end of each trench. V E. ENGINEERING ,PLANS AND CONSTRUCTION 1. Reference Guidelines. In addition to the requirements set forth herein, design and construction of PDST systems shall generally follow guidelines contained in the following references: a. "Onsite Wastewater Treatment Systems Manual", U.S. Environmental Protection Agency, February 2002 and as amended. b. "Design Manual — Onsite Wastewater Treatment and Disposal Systems", U.S. Environmental Protection Agency, October 1980. Onsite Systems Manual - Part 4 (9/2013) Page 46 2. Engineering Plans. Engineering plans for PDST systems shall include: a. All relevant elevation data and hydraulic calculations. b. Specific step-by-step construction guidelines and notes for use by the installer. c. Erosion control plan for any site over 20%, utilizing cover fill or with design flow >1,000 gpd; d. Recommended make and model of all components; ,r e. Recommended pump system components with cut -sheet depicting float settings; f. Control panel programming; {. g. An inspection schedule listing critical control points 3. Construction Inspection. At a minimum, inspection of the PDST system\installation should include the following. Joint inspecti6h*,by the designer, contractor, anI&DEH may be required. Pre -construction inspection where the construction_ staking or marking of the various system components is and const -r•' tion procedures discussed; ® Water tightness of septic tank ain dosing (pump) tank.Y / Layout and excavationof dispersal tre'nches and piping; Sand and=dr\ain�materialsjand placement;_.3 Piping -installation q,iy-d'raulnc ("squirt") test of the distribution system; f°fFunction ing and'setting o 'all control devices; and 4 ',Final Inspection to,verify that all construction elements are .in conformance with the approved.plans and specifications, all performance wells are installed; and erosion control has been�completed. F. MANAGEMENT'REQUIREM ENTS. Recommended minimum procedures and frequency for inspection, maintenance, monitoring and reporting activities for pressure -dosed sand trench systems are outlined in Table PDST-3. Onsite Systems Manual - Part 4 (9/2013) Page 47 Table PDST-3. Pressure -dosed Sand Trench Manaeement Reauirements Onsite Systems Manual — Part 4 (9/2013) Page 48 Work Frequency Inspection Conduct routine visual observations of disposal field and downslope area and surroundings for wet areas, pipe leaks or damage, soil Every 6 to 12 months. erosion, drainage issues, abnormal vegetation, or other problems. ■ Perform all inspections of pump and appurtenances (see Guidelines for Dosing Pump System). " Maintenance ■ Purge laterals, squirt and balance: f`' ` ■ Distribution system ■ Exercise valves to ensure functionality. a' 'ti. maintenance annually. ■ Perform all maintenance work as recommended by equipment ' "other maintenance as required. manufacturer for any special valves or other components ` = 4, ■ Investigate and repair erosion, drainage or other disposal.field" problems, as needed..` ,ti • ■ Investigate and perform distribution system.correct ve�work, as"\v. .,}5 required. �, ■ Record work done. Water ■ Measure and record water levels,in.(2) types of trench observation Report findings to County per & 11�1Monitoring wells: 1) extending to the pea gravel sand interface; and 2) -� permit requirements. Sampling extending to sand -soil interface. Report any continuous ponding ■ Measure and record water levels in dispersal-field„monitoring wells ) at sand interface that may as applicable, per permit requirements-\ °��.:' `' `l indicate the formation of ■ Obtain and analyze water samples from monitoring wells, as, restrictive biomat. applicable,,perpermit requirements. �r Standard report to include dates, observation well and monitoring well readings and ' other data collected, work performed, corrective actions taken, and performance summary. Report public health/water -- ._A quality emergency to County immediately. Reporting .`Report findings to. DEH per permit requirements. According to permit conditions, `Standard report to:include dates, observation well and monitoring typically every 1 to 2 years, well. eadings and.other data collected, work performed, corrective depending on system size, actions taken Jarid performance summary. usage, history, location. ■ Report public health/water quality emergency to DEH immediately. Onsite Systems Manual — Part 4 (9/2013) Page 48 FILTER FABRIC SILT BARRIER PRESSURE DISTRIBUTIO PIF DOUBLE WASHED PEA GRAVEL INSPECTION RISER W/ rr�r n rrrr..n n 6" MIN. 6" TO 12", SEE BELOW NSPECTION WELLS UTILITY BOX INSPECTION WELL EXISTING GRADE FILTER FABRIC SILT BARRIER O To - DOUBLE DOUBLE WASHED 6" MIN. PEA GRAVEL ;•� :; t ,t•.;;:;• 12" TO 24" MIN. FOR SEPTIC TANK EFFLUENT, 6" TO 12" MIN. FOR SUPPLEMENTAL TREATMENT MEDIUM SAND FILL 12" TO 36" (EFFECTIVE APPLICATION AREA) END VIEW PRESSURE DOSED SAND TRENCH GUIDELINES FOR RAISED SAND FILTER BED A. DESCRIPTION A raised sand filter bed, sometimes referred to as a bottomless sand filter, combines features of an intermittent sand filter and a mound system. It consists of a raised or,terraced sand bed, commonly supported by a low retaining wall or bulkhead, where the bottom surface is even with or slightly below ground surface and forms the absorption surface. This alternative is intended to be used only for repair or replacement OWTS, notxto serve new construction. The system may be designed for use with or without supplementa'I treatmdn.t ahead of the raised sand bed. The raised sand filter bed provides additionaF'— ishing treatment and final dispersal of water into the ground. /f B. CONSTRAINTS ADDRESSED 1. High groundwater; , 2. Shallow soil over fractured rock or coarse alluvia 3. Shallow soil over impe 4. Slow percolation`at stan 5. Moderately steep~siope� 6. Limited dispersal, area. C. SITE'CRITERIA 1. Setback's., Horizontal;sei applicable to,conventior section B11-67,., eable soil or 6 f lard dispersal ,and. _ _- depths; back requirements for raised sand filter beds shall be those al disposal fields, as specified in Santa Clara County Code 2. Vertical Separation Requirements. a. Depth to Groundwater. Minimum depth to seasonal high groundwater shall be 2 feet below ground surface. For percolation rates faster than 5 mpi, depth to groundwater shall be 3 feet. b. Soil Depth. Minimum depth of soil, as measured from ground surface to impermeable soil or bedrock, shall be 2 feet. This soil depth requirement shall Onsite Systems Manual - Part 4 (9/2013) Page 49 apply within the disposal field and in the adjacent area extending.a distance of 25 - feet downslope of the raised sand filter bed. c. Depth to Fractured Rock. Minimum depth of soil, as measured from ground surface to fractured, permeable rock or coarse alluvium, shall be:2 feet. This soil depth requirement shall apply within the disposal field and in the adjacent area extending a distance of 25 -feet downslope of the raised sand filter bed. 3.. Percolation Rate. Average percolation rate for raised sand filter bed systems shall be within the range of 1 to 60 minutes per inch (MPI), as determined'.frrom testing at.2 to 3 feet depth. These percolation requirements shall apply within the disposal field and in the adjacent area extending a distance of 25 -feet downslope of#e raised sand filter bed. . 4. Ground Slope. a. Maximum ground slope for raised san`d.filter beds shall be 30%. y . b. Any raised sand filter bed -system located on`slopes greater than 20 percent shall require the completion of a geotechnical report'and slope stability analysis as specified in Santa Clara CountyCode ection 1311-83. S. Dual System. Per Santa -C beds, each onehun r6i shall be installed and inte to allow alternate use of i . /7 D. DESIGN CRITERIA 1. Treatment. The folic use of'raised sand fili ra County Code`section 81-1-i 7(d), two raised sand filter cent of the total size required for the design sewage flow, netted witK-a\ n approved flow diversion device, intended �'tw�o beds. ng treatment requirements shall apply in connection with the bed systems: a. Primary (septic tank) treatment shall be the minimum level of treatment, and \ "/ shall be.a'cceptable with the design includes sand fill depth of 24 inches. b. Supplemental treatment, using an approved alternative treatment system: identified in this Manual, may be used to allow reduction of the sand fill depth to 12 inches. 2. Design Sewage Flow. Raised sand filter bed systems shall be designed on the basis of the projected sewage flow, determined in accordance with sewage flow estimation guidelines in Part 3 of this Manual. Onsite Systems Manual - Part 4 (9/2013) Page 50 0 3. Pressure Dosing. Wastewater effluent from the supplemental treatment system shall be applied to the raised sand filter bed system by pressure dosing, utilizing a pump system. The pressure distribution system shall be designed in accordance with accepted engineering practices to achieve, at a minimum:. a. Uniform dosing of effluent over the surface application area of the raised=sand filter bed; b. Adequate flow rate, screening of effluent and suitable piping network to preclude solids accumulation in the pipes or clogging?6f-di charge orifices; r.. c. Suitable access provisions for inspection, testing and`adjustment of the pressure distributionsystem; ; ' d. Dosing volume to achieve a minimum of 3"[6,5 doses per''ciay,at design flow conditions; and e. At least one distribution lateral foOevery.36 inches of distribution bed -width. Additional requirements for design and construction ofp"ressure distribution piping systems contained in "Guidelines for Pressure Distribution Systems" shall also apply. 4. Pump System. The pump system shall b' of the size and type to meet the hydrauli constructed in accordance with purrip;sy. -� ^a .Manual. 5. Containment -Liner. The raised sand filte containment line'ral'ong all -sides of the fi appropriate.fo'r-sewage applications; (b) gn-requirements; and (c) designed and requirements provided in Part 3 of this I be provided with an impermeable ��bed to prevent lateral leakage out of or into the -filter. The liner shall-6xtenda;mir Rnum of 12 inches below native grade. The liner shall cons st ;of either >(a) 30 mil plastic; (b) reinforced poured -in -placed concrete; ,or�(c) an equivalent imperriaeable structure. 6.. Finished Grade. The,,finished grade of the raised sand filter bed shall.be above the surrounding ground dleyation. Above -ground installation shall be structurally supported with retaining wall(s);'as required. 7. Bed Width. Nlrrum width of the sand bed shall be 10 feet. 8. Shape. The raised sand filter bed shall not be restricted as to its shape in plan view. 9. Multiple Units. The raised sand filter bed may be divided into compartments or multiple units. 10. Sand Filter Media. Onsite Systems Manual - Part 4 (9/2013) Page 51 Lq a. Sand Specification. The sand media shall be.a medium to coarse sand that meets the following gradation specifications: Sieve Size Percent Passing 3/8 100 #4 90-100 #10 62-100 #16 45-82 - '� #30 25-55 ' #50 5-20 #60 0-10 #100 0-4 #200 0-2 rf y .. Documentation of laboratory sieve analysis results f 'r°the proposed sandXfill material shall be supplied to DEH to verify conformance with the above specifications. b. Sand Depth. The minimum depth -of sand fill, below the gravel distribution bed, shall be 24 inches for septic tank effluent,.and 12 inches for supplemental treatment. 11. Wastewater ApplicationaRate. The wastewater application rate used for sizing the basal area of the sand filter bed (Le., sand -soil interface) shall vary according to soil percolation rate of the native.soil as follows N.r. �-'-T-able RB -1 „y r `' 'BasaCWastew6tA_ Ier Application Rates for Raised Sand Filter Beds 'P;ercolatipo—In ate Wastewater Application Rate . (gpd/ft2) if. ;� 1-5 1.2 10 1.2 24 1.2 30 1.12 45 0.68 60 0.53 90 0.25 91-120. 0.2 ' Interpolate between reference values for other percolation rates; See end of Part 4 for an expanded table listing interpolated values. Onsite Systems Manual - Part 4 (9/2013) Page 52 Reduction in the above wastewater loading rates or other provisions to insure the long- term integrity and performance of the raised sand filter bed may be required for high strength .waste flows, such as from restaurants. 12. Minimum Basal Area Sizing. At a minimum size of the basal area of the raised sand filter bed shall be determined by dividing the design wastewater flow (in gpd) by the applicable wastewater loading rate per Table RB -1. 13. Linear Loading Rate. The length of the raised bed shall be sizeAN omeet maximum linear loading rate criterion as follows: {` a. Effective Length. The effective length (L) of the raised bed,for determining the linear loading rate shall be the total length,of th`e raised`bed,'along the downslope edge. b. Wastewater Flow. The wastewate'rflow.used for•determining theainear loading rate shall be as follows: 100 gpd/bedroom for residentia_'Vseptic systems (note: 150 gpd/bedroom4use&for system design); ;,4 a i design sewage flow rate f r commercidl;institutional, industrial an multi -residential septic systems ,.-, c. Loading Rate Maximum linear loading rates for raised sand filter bed systems sizingshall,yary according to soil depth, ground slope, and percolation rate as �:,-> indicated`in Table ,M2. If a varianc,eefrom these criteria is proposed, it must be supported 6i -detailed-gr uo ndwatefmounding analysis carried out in accordance with;accepted meth movement in soilssa`i Table 2to215 :/ 2.5 to 3 3to4 >4 dology and/or scientific references dealing with water d,.utilizing site specific hydraulic conductivity data. T'2. Maximum Linear Loading Rates (gpd/lineal foot) Onsite Systems Manual - Part 4 (9/2013) Page 53 14. Gravel Distribution Bed. a. Material. The distribution bed shall consist of 3/8 -inch double -washed pea gravel, substantially free of'fines. b. Depth. Pea gravel shall extend a minimum of 6 inches below the invert and.2 inches above the top of the distribution piping. If the distribution piping is installed with chambers, the pea gravel depth below the distribution pipe may be reduced from 6 inches to 4 inches, and the 2 -inch pea gravel cover may be eliminated. 15. Silt Barrier. The gravel distribution bed shall be either polyester; :nylon or polypropylene, or any combination thereof, and shall be suitable,fornderdrain applications. Filter fabric shall be non -woven, shall not act as a wicking ,agent and shall be permeable. 16. Soil Cover. a. Material. A soil cover shall be placed over the distribution bed, consisting of a - medium, loamy -textured soil'.��. b. Depth. Soil cover depth shall b6.a minimum of 12 inches and a maximum of 18 inches over the top of the distribution ed.` oil^cover shall be crowned or sloped to promote rainfall runoff. -f 17. Inspection Wells -A minimum of four (4) inspection wells- shall be installed within and around raised sand filter bed.as follows: .,,�- _._..,mow ' . _ � ----...�_ • a, One shall be -located -near the center of the raised bed, extending from the fill surface to�the bottom of the gravel distribution bed. ;r__•b One shall be located near`the center of the raised bed, extending from the fill surface to the sand'soil interface. C. One:sR ll'be located 5 to 10 feet upslope of the raised bed system, midway along the length of the�at-grade, extending from the ground surface to a depth of 5 feet or to contact,:with,impermeable materials, whichever is less. d. One shallb4 located midway along the downslope length of the raised bed, within 10 to 15 feet from the edge of th bed, extending from ground surface to a depth of 5 feet or to the depth of impermeable materials, whichever is less. e, Inspection wells shall be constructed of 2" to 4" diameter pipe (or equivalent), equipped with a wrench -tight cap or pipe plug and a bottom cap. All wells shall be perforated beginning at a depth of 18 inches below grade and extending to the bottom of the pipe. Perforations shall consist of hacksaw slots at nominal 1" spacing Onsite Systems Manual - Part 4 (9/2013) Page 54 or commercially -slotted pipe. Inspection wells shall be sealed with a bentonite or concrete annular seal (or equivalent) to prevent surface infiltration. E. ENGINEERING PLANS AND CONSTRUCTION 1. Engineering Plans. Engineering plans for raised sand filter.bed systems shall include: a. All relevant elevation data and hydraulic calculations; b.. Design layout and details for sand filter bed -construction-; c. construction-;`c. Specific step-by-step construction guidelines and notes..for,use by the installer; d. Erosion control plan; e. Recommended make and model of all components; f. Recommended pump system components with cut -sheet depicting float settings; g: Control panel programming; and h. An inspection schedule listing critical control points. 2. Construction Inspection. At a minimum,~ nspection of the raised -sand filter bed system installation should include the following:\ Joirit-in p ct on by the'6esigner, contractor, and DEH may be required. ';<;` • Pre-constructio spection where sand filter-bdd{is provided and con • Water -tightness bf dosing=(pump) �; `• : y .., .,,.I Z.,y Raised sand bed dimensions, strut e `z,, 'nd material a construction staking or marking of the raised tion,proceduresdiscussed; re and liner; + Pipin'g it Ystallation"and hydraulic ("squirt") test of the distribution system; • Function and,setting of all control devices. • Final Inspection to verify that all construction elements are in conformance with the approved plans and specifications, all inspection wells are installed, and erosion control has been completed. Onsite Systems Manual - Part 4 (9/2013) Page 55 F. MANAGEMENT REQUIREMENTS Recommended minimum procedures and frequency for inspection, maintenance, monitoring and reporting activities for pressure -dosed sand trench systems are outlined in Table RB -3. Table RB -3. Raised Sand Filter Bed System Management Requirements Onsite Systems Manual — Part 4 (9/2013) Page 56 Work Frequency Inspection ■ Conduct routine visual observations of sand filter bed system and Eve?ry 6 to 12 months. perimeter area and surroundings for wet areas, pipe leaks or damage, structural condition of filter bed, soil erosion, drainage./. . 't issues, abnormal vegetation, gophers or other absorption field/ problems. 1 ■ Perform all inspections of pump and appurtenances' (e_G;uidelines �..y . for Dosing Pump Systems). Record observations. Maintenance Purge laterals, squirt and balance. Distribution'system ■ Exercise valves to ensure functionality. maintenance annually. ■ Perform all maintenance work as recommended by equipment., Other maintenance as required. manufacturer for any special valves -or other components. ■ Maintain sand filter bed surface lands p 'vegetation, as req'd. ■ Investigate and repair erosion, drainage, structural -problems or other problems, as needed. ■ Investigate anddistribution system corrective work,as req'd ,perform F` V/ ■ Record work done.-` i Water ■ Measure and record vubter,levels in observation wells in distribution ■ Measure system water levels Monitoring & bedsand,fill and aroundjsystem perimeter. annually. Sampling ■ Obtain and "analyze water samples from monitoring wells, as ■ Other monitoring according to per permit requirements ' permit conditions, as ,,_,.applicable, applicable. Reporting,."fj ■ Repo&findinds,to DEH-perpermit.requirements. According to permit conditions, ■ Standard report to.include date observation well and monitoring typically every 1 to 2 years, 6`. well readings and other data "collected, work performed, corrective collected, depending on system size, actions taken, ansummary. usage, :history, location. Report.public health%water quality emergency to DEH immediately. . Onsite Systems Manual — Part 4 (9/2013) Page 56 INSPECTION RISER WITH THREADED END CAP (TYP.) INSPECTION WELL (TYP.) 12" MIN. SUiL HLL PEA GRAVEL DISTRIBUTION BED; 6" MIN. BELOW PIPE, 2" MIN. ABOVE PIPE FILTER FABRIC SILT BARRIER STRIP VEGETATION AND o0 og88° $v ,°oao�.m a oa °40° O�ooJyg° °"o C:90 V.��° °° 000 PLOUGH OR RIP PRIOR ° °0 0° ° ° s 4°' ° rPo° °°0° o°p 0 d' °° 0 6°� ao, 00 °o ° Oo '000 0 0 .Oo o ° °o 0 TO PLACEMENT OF SOIL 00 `�� oo0�yo 4sd'a°8a ' ° o � 8o goo °� .0 0 0 0 00000,30 g° 0 0 0 8g o o $ o°�°c9 00°00° $ oon o8 ° ° COVER FILL °�p8 0pmo°oo o °° o o ° 0 0 8 ��o°o ono o°Oo°�o� o°o¢p°B�Qy`�mc 0°S0 o'°OO0000cp°o $o �e °o x'0000 ° 00 a �0 o4ioo o° 0000° o°o °0 Q)o°a 000°0 080 8o 00 00 000 EXISTING GRADE MEDIUM SAND FILL; 12" MIN. EXTEND LINER BELOW GRADE, 12" MIN. PVC PRESSURE LINE FROM DOSING PUMP END CROSS-SECTION _ RETAINING STRUCTURE WITH INTERIOR LINER SECURED TO INSIDE SURFACE (TYP.) PRESSURE DISTRIBUTION PIPING RAISED SAND FILTER BED GUIDELINES FOR SUBSURFACE DRIP DISPERSAL A. DESCRIPTION 11 Subsurface drip dispersal is a method for disposal of treated wastewaterthat uses special drip tubing designed for use with wastewater. The dripline is placed normally 8 to 12 inches below ground surface and makes use of the most biologically active s �I-zone for distribution, nutrient uptake and evapotranspiration of the wastewater. A drip dispersal system is' comprised of small -diameter (%" -1") laterals ("driplines"), usually spaced about 24 incl 'es apart, with small - diameter emitters (1/8") located at 12 to -24 inches on`eenter`along the drli - linel, Effluent is conveyed under pressure to the laterals, normally with timed.doses. Priorto'dispersal.the effluent.requires supplemental treatment. ��%_.; Drip dispersal has several advantages, including: (a) it can,be'effective in very shallow soil conditions since it distributes the wastewater very uniformly�to substantially all of the available soil in the field; (b) it can be installed in multiplb small discontinuous "zones", allowing the hydraulic load to be spread widely rather than concentrated in one main area; (c) installation on steeper slopes causes less soil disturbanc' ,and erosion 'or>slope'stability hazards; and (d) water movement away from -the drip emitters=s.substantially by unsaturated/capillary flow, which maximizes contaet:with-and'treatment byahe soil B. CONSTRAINTS ADDRESSED 1. High.groundwater.; �f X 2. Shallow soil over impermeable soil or bedrock; 3. Shallowsoil over fractured rock;'o'r coarse alluvium; 4. Slow percolation at stan/dard dispersal trench depths; N / 5. Steep slopes;:;.:':' i f` 6. Limited dispersalarea; and 7. Large and/or dense tree cover. C. SITE CRITERIA 1. Setbacks. Horizontal setback requirements for drip dispersal systems shall be.those applicable to conventional disposal fields, as specified in Santa Clara County Code section B11-67. Onsite Systems Manual - Part 4 (9/2013) Page 57 2.. Vertical Separation Requirements. a. Depth to Groundwater. Minimum depth to seasonal high groundwater, as measured from the bottom of the dripline, shallvary according to soil percolation rate as follows: Percolation Rate, MPI Depth to Groundwater 1-5 3 feet* 6-120 2 feet *Note: Where drip dispersal field is combined with a raised sand filter bed, the depth to groundwater may be reduced to 2 feet, as measured`from ground surface. b. Soil Depth. Minimum depth of soil, as measured fr'orh"the bottom of the dripline to impermeable soil or rock, shallybe' 2 feet.1 e' \ . 3. Percolation Rate. Percolation rates for subsurface drip dispersal systems shall be within the range of 1 to 120 minutes p,er-.i ch (MPI); as determined byYt suing at depths of 12" to 24". 4. Ground Slope. a. Maximum ground slo b. Any drip dispersal system le require the_;completion of a specified in Santa\�Clara Cou for drip°dispersal shall be 50 percent. ad<on'slopes gredter than 20 percent shall ifechnica report and slope stability analysis as Code section 1311-83. 5. Dual System. 'Per Santa:Clar_a County Code section 1311-67(d), two drip dispersal fields, -each one iiun r'ed'per-cent,pf.the•iota l size required for the design sewage flow; shall be installed and int re connected with an approved flow diversion device ,�. X, . `(pressure-rated);:••to allow alteerrn ate or combined use of the two fields. D. DESIGN' CRITERIA 1. Treatment: The.following treatment requirements shall apply in connection with the use of subsurface dr odispersal systems: a. Wastewater effluent discharged to any drip dispersal system shall be treated to at least a secondary level through an approved supplemental treatment system, in accordance with applicable guidelines provided in this Manual. b. All drip dispersal systems shall include a filtering device capable of filtering particles larger than 100 microns; this device shall be located downstream of the supplemental treatment system. Onsite Systems Manual - Part 4 (9/2013) Page 58 2. Design Sewage Flow: Subsurface drip dispersal systems shall be designed on the basis of the projectedsewage flow for the structure or facility being served, determined in: . accordance with sewage flow estimation guidelines in Part 3 of this Manual. 3. Wastewater Application Rates: Wastewater application rates used for sizing drip dispersal fields shall be based on soil percolation rate in accordance with the criteria in Table DD -1. In applying these criteria, the wastewater application area refers to the ground surface area encompassed by the drip dispersal field. Table DD -1. Wastewater Application Rates for Subsurface Drip Dispersal Fields *Soil types listed for reference information only 4. Dripfield Sizing: v a. Minimum sizing of the dripfield area shall divided"by the -applicable wastewater ap f shall barb"esed on site-specific percolation data. equal to the design wastewater flow tion rate from Table DD -1. b For sizing purposes; effective: ground surface area used for.drip field sizing calculations -shall be limited no more thane 0 square feet per drip emitter. For example, 200 lineal feet. ofdripline with `'emitters�at�2-foot spacing would provide a total.of 100 emitters (200%2) and could be�'used for dispersal to an effective area of up to 400 ft2 (100 emitters -,x 4 -ft /emitter). Conversely, if wastewater flow and percolation design information:-ndicate',the need for an effective area of 1,000 ft2, the dripline design and layout would have to be configured to provide a minimum of 250 emitters spaced over the required 1,000 ft2 dispersal area. c. Dripfields may be divided into multiple zones which may located in different areas of a site, as desired or needed to provide the required dripfield size. A single continuous dripfield area. is not required. However, any areas proposed for drip dispersal shall be supported by field observations/measurements to verify conformance with soil suitability and other site requirements. Differences in soil conditions and percolation characteristics from one zone to another may require the use of correspondingly different wastewater application rates and dripfield sizing for each zone. Onsite Systems Manual - Part 4 (9/2013) Page 59 e, WastewaterRat Application SoiLType* .Soil Percolation Rate ,e. (MPI) - v (gpd/ftZ)�_ = Coarse Sand 1-4.N\1.4 Fine Sand 1.2 Sandy Loam. 11-20 '�.:, r' 1.0' Loam 21-30�_ 0.7 Clay Loam >31-45 w; 0.6. - Silt -Clay Loam °f ~46-60 0.4 Clay, non -swell \\6140.4„ '` 0.2 Clay, swell 91-120;%' 0.1 *Soil types listed for reference information only 4. Dripfield Sizing: v a. Minimum sizing of the dripfield area shall divided"by the -applicable wastewater ap f shall barb"esed on site-specific percolation data. equal to the design wastewater flow tion rate from Table DD -1. b For sizing purposes; effective: ground surface area used for.drip field sizing calculations -shall be limited no more thane 0 square feet per drip emitter. For example, 200 lineal feet. ofdripline with `'emitters�at�2-foot spacing would provide a total.of 100 emitters (200%2) and could be�'used for dispersal to an effective area of up to 400 ft2 (100 emitters -,x 4 -ft /emitter). Conversely, if wastewater flow and percolation design information:-ndicate',the need for an effective area of 1,000 ft2, the dripline design and layout would have to be configured to provide a minimum of 250 emitters spaced over the required 1,000 ft2 dispersal area. c. Dripfields may be divided into multiple zones which may located in different areas of a site, as desired or needed to provide the required dripfield size. A single continuous dripfield area. is not required. However, any areas proposed for drip dispersal shall be supported by field observations/measurements to verify conformance with soil suitability and other site requirements. Differences in soil conditions and percolation characteristics from one zone to another may require the use of correspondingly different wastewater application rates and dripfield sizing for each zone. Onsite Systems Manual - Part 4 (9/2013) Page 59 5. Pressure Dosing. Secondary -treated effluent shall be delivered to the dripfield by pressure, employing a pump system and timed dosing. The pressure distribution system shall be designed in accordance with accepted engineering practices and manufacturer recommendations for drip dispersal systems to achieve, at a minimum:. a. Uniform dosing.of treated effluent; b. An adequate dosing volume and pressure per manufactures c. Adequate flow rate, final filtering of effluent and suitable p solids accumulation in the pipes and driplines or clogging`ol d. A means of automatically flushing the filter and driplines at e. Suitable access provisions for inspection, to . i.h and' adjust components. Additional requirements for design and construction of pre systems contained in "Guidelines for Pressure Distribution, 6. Pump System: The pump system: shall be: (a) appropriat of the size and type to meet the hyd ar ulic design requires constructed in accordance with pump systemarequiremei Manual. 7. Dripline Material:f•Dripline shall be mannu quality wastewater, with.,mihimum 45 mi inhibitor(s),,,and means oeprotection agai 's guidelines; nng>network to preclude discharge emitters; iegular intervals; and nen of the dripfield and 0 shall also apply. for sewage applications; (b) ents;,,and (c) designed and s_ provided in Part 3 of this ctured ar dIntended for use with secondary abing wall thickness, bacterial growth t root intrusion. 8. Dripfield Layout: The bottor�of`each �driplin6 row shall be level and parallel to the slope 9. Dripl ne Depth:`The driplin&depth shall be installed at a depth between eight and twelve < inches below native°g4cle. Deeper placement of driplines may be considered by DEH on a case=by-case basis. 'E 10. Length of individual driplines: The maximum dripline length.shall be designed in accordan eawith accepted engineering practices and in accordance with the �.., - 'a. // manufacturer'scriteria and recommendations. l 11. Line and EmitteriSpacing: Line and emitter spacing shall be designed as appropriate for soil conditions, slope, and contour. Emitters shall be located.at no less than 12" from the supply and return manifolds. 12. Dual System Operation. Unless exempted by the Director, all drip dispersal systems shall be installed as dual (200% capacity) drip fields, and shall normally be operated with -both fields in use. Doses may be alternated among different zones in both the primary and secondary fields, or all zones may be dosed simultaneously. Secondary drip fields should not be left dormant for long periods of time (e.g., more than a few weeks at a time). Onsite Systems Manual - Part 4 (9/2013) Page 60 13. Inspection Wells. A minimum of three (3) inspection wells, minimum 3 feet in depth, shall be installed for the purpose of monitoring groundwater levels or for water quality sampling within and around subsurface drip dispersal fields as follows: a. One well shall be located within the dripfield area. b. One well shall be located 10 to 15 feet up -gradient of the dripfield. c. One well shall be located 10 to 15 feet down -gradient of the dripfield. d. Inspection wells shall be constructed of 2" to 4" diameter pipe (or equivalent), equipped with a wrench -tight cap or pipe plug and a bottom cap. All wells shall be perforated beginning at a depth .of 12 inches below grade•and extending to the bottom of the pipe. Perforations shall consist of ha:eksavvAots at nominal 1" spacing, or equivalent commercially -slotted pipe. `l nspection,,wells shall be sealed with a bentonite or concrete annular seal (equivalent) to prevent surface infiltration. �. E. ENGINEERING PLANS AND CONSTRUCTION 1. Reference Guidelines. Installation of subsurface drip dispersal systems shall be in accordance with applicable manufacturer guidelines and recommendations. 2. Engineering Plans. Engineering plans,for subsuu fa`ce•,drip dispersal systems shall include: a. All relevant elevation data and hydraulic calcul ons; b. Specific }step by -step construction guidelines and notes for use by the installer; c. Erosion control, planjfgr any site over096, utilizing cover fill or with design flow >1,000 gpd` d Recommended make and model of all components; V `e, Recommend ed"p}ump `system components, with cut -sheet depicting float settings; Control panelprogramming; and g. An:irispection schedule listing critical control points. Construction'I pectipn. At a minimum, inspection of the drip dispersal system installation sho6ld,i6clude the following. This is in addition to inspection work required for the treatmer_ system. Joint inspection by the designer,:contractor, and DEH may be required. Pre -construction inspection where the construction staking or marking of the drip lines, supply and return piping, pump system and appurtenances is provided and construction procedures discussed; o Watertightness of effluent dosing (pump) tank; Onsite Systems Manual - Part 4 (9/2013) Page 61 Drip field layout, piping materials and installation, and all associated valves and connections; *. Hydraulic testing of the drip system; a Functioning and setting of all control devices; and Final Inspection to verify that all construction elements arerin`"conformance with the approved plans, specifications, and manufacture recommendat ons; all inspection wells are installed; and erosion control has been com" oleteil• . F. MANAGEMENT REQUIREMENTS. Y Recommended minimum procedures and frequencq,,for inspection, maintenance; monitoring and reporting activities for pressure -dosed sand trench syste'rns are outlined ir4able DD -2. Table DD -2. Drip Dispersal System Management. -Requirements ^.oaf Onsite Systems Manual - Part 4 (9/2013) Page 62 Work Frequency Inspection Conduct routine_visual observations of drip°field, downslope,76a and Every 6 to 12 months. surroundings for wet'area's, pipe leaks or damage, soil erosion, drainage issues, abnormal ='vegetation, gophers or other problems. ■ Conduct routi.4physical inspections of system',eomponents, - "-� ._ including valves; filters;,and headworks box(es),/, F� Perforin special inspections of drip fieldatime of any landscaping ,e '� work or other digging m drip field area. Perform inspections of dosing''pump(s) and appurtenances (see Guidelines for.;Dosing Pump°Systems). Record observations,.-- bservation;Maintenance Maintenance '■,. Manually remove "and clean filter. ■ Clean filter every 6 months. ■ `Clean,and check,.operation of pressure reducing valves. ■ Other maintenance annually. ■ Cleanflush valves and vacuum release valves. Water Measureand'record water levels in dispersal field monitoring wells, According to permit conditions, Monitoring & as applicable, per permit requirements. if applicable. Sampling ■ Obtain and analyze water samples from dispersal field monitoring wells, as applicable, per permit requirements. Reporting ■ Report findings to DEH per permit requirements. - According to permit conditions, ■ Standard report to include dates, monitoring well and other data typically every 1 to 2 years, collected, work performed, corrective actions taken, and depending on system size, performance summary. usage, history, location. ■ Report public health/water quality emergency to DEH immediately. Onsite Systems Manual - Part 4 (9/2013) Page 62 AIRNACUUM RELIEF VALVE AT HIGH'. POINTS (TYP.) POLYETHYLENE DRIP TUBING; 24" DRIPLINE SPACING;_ EMITTERS @ 24" O.C; 8-12" DEEP (TYP.) DISPERSA L AREA PERIMETER ---------- - - - - - - r .. o-�- - E PVC SUPPLY MANIFOLD o- -1 -a- -a. ---M I PUMP CHAMBER I I I o- o- a- -e- -a -fl I SUPPLEMENTAL TREATMENT o - a- -EB--a -oI SEPTIC TANK o- o- a- -a- -a -0 F I I. - o-a--E�--EM I I r I EM - a- -a- -a -o I -- O O - - - - © „ rg,,1 o- a- -a- -a --a I PVC FLUSH RETURN MANIFOLD FLUSH VALVE, SOLENOID OR PVC FLUSH RETURN LINE MANUAL, NORMALLY CLOSED HEADWORKS, WITH FILTER, VALVES & PRESSURE REGULATION DRIP DISPERSAL SYSTEM SCHEMATIC PRESSURE REGULATOR TO SUBSURFACE DRIP DISPOSAL FIELD FROM PUMP CHAMBER Al .5' SEPARATION VORTEX IS REQUIRED FILTER BETWEENT THE PRESSURE SUPPLY. MANIFOLD. GUAGE AIR VENT AND 1ST DRIP EMMITER FROM SUBSURFACETO SEPTIC DRIP DISPOSAL FIELD TANK SOLENOID FIELD FLUSH VALVE AUTOMATIC HEADWORKS 18" c TO 12" GEOFLOW . . ARV 05 AIR/VACUUM 6 BLANK PVC ELL TO RELIEF ROUND DRIPLINE GEOFLOW PVC TEE COMPRESSION 1/2" PVC VALVE VALVE (TYP.) DRIPLINE (TYP.) ADAPTER (TYP.) COUPLING BOX 1/2" SCH. 80 PVC PVC HEADER NIPPLE (LENGTH SUPPLY MANIFOLD AS REQUIRED) THREE1 BRICK END FEED/ FLUSH MANIFOLD SUPPORTS `""' `'' `' PEA GRAVEL SUMP PVC PIPING 1" AIR / VACUUM RELIEF AND FITTING (PUMPED TO PVC) DRIP DISPERSAL DETAILS EXPAND WASTEWATER APPL TABLE; m � 1 Onsite Systems Manual - Part 4 Page 61 - Table 1. Standard Wastewater Application Rates.- Septic Tank Effluent Percolation Rate Applcatwn Rate r Percolation Rate Application Rate ` MPI 1 to 5 1.20 51 0.41 6 1.12 52, 7 1.04 53 0.40 8 0.96,. 54' .: 0:39:- 9 0.88 55 0.38 10 0 80 .56 0.38,E 11 0.78 57 0.37 12; 077, 13 0.75 59 0.36 074 ,., :`.60.- ": 0:35= . _. 15 0.72 61. 0.35 16-0.70 ,. ``_ '. - -62 17 0.68 63 0.34 64 19 0.85 65 0.33 20..- _ , _ 0.64.. _ x :66.: 0.33 . '.21 0.63 67 0.33 22 0 62 23 0.61 69 : 0.32 24 _ ' : 0 70 25 0.59 71 0.31 -_,,,_26,0.59= =:`.: ; ..:' ;.: = _ . 72:. ': 0 31:. 27 0.58 73 . 0.31 57 . Y 7..4 0:30' _. 29 0.57 75 0.80 30. °. 0.56 76 - 0.30 ,. 31 0.55 77 0.29 0. 33 0.54 79 0.29 - 34 35 0.52 81 0.28 36 37 . 0.51 83' 0.27 0 50.., ` 84:: 0 27 39 0.49 85 0.27 w 40 m 0.49 86' ` 0.26 41 0.48 87 . 0.26 . 42_ 047 ?0:26: 43 0.46 89 0.25 ,0:25 45 0.45 91-120 0.20 44 47 0.44 49 0.43 50 .0 42 r ;;_ Table 2. Enhanced Wastewater Application Rates - Supplemental Treatment Percolation Rate Application Rate MPI 2 F Percolation Rate ; Application Rate__. . MPI 2.., 1-24. 1.20: 61 0.52 25'. , 11:9. 16 26 1.17 63 0.50 27 :. 1 16 . :. :. « X64 28 1.15. 65 0.48 0.47. 30 1.12 67 0.46 32 1.06. 69 0.45 337 _ , _ ° - 70: _ _ 0.44 34 1.00 71 0.43 ' 35; V 0.97 ..` .72 _:� 0 42 ..; 36 0.94 73 0.41 37 0 91 - .. 74 :._:._: `_ .0 40..::4... 38 0.89 75 0.39 39,. :: -0.86 -76: 0.38 40 0.83 77 0.37 0 80 : '` _ 78 . 0.36 42 0.77 79 0.35 74 -0.74- 44 0.71 44 81 0.33 . 45 ...; 0.68: :: ; .. - : .82" . _ `.0 32, 46 0.67 83 0.31 :.:. 47_ .. „ 0 66 ,. _,: 84 0 31 .'. . 48 0.65. 85 0.30 0:29 , 50 0.63 87 0.28 5_( 0.62 :. .' _ 88 52 0.61 89 0.26 Table 4. At Grade System - Wastewater Application Rates (Septic Tank Effluent) Percolation Rate Application Rate MPI s: Percolation Rate ; - Application Rate y MPI , z . a _ �_ .- 53 0.40 54: : 0:39. _' ... .., 55 0.38 - - 5 7 : 8 3 59 0.36 60.. 0:35 :... _ 6 0.35 ;...62 _ .. _ 0.54- 63 0;:34 :° ",64 ;. 3 65 _ ::0:33.. 6 . 0.33 67.. 8 0.32 71 0.31 : 72 ::.. _ 0:31, .73 0.31 74 -300. 75 G,30 - 76 77 79 70:29 _ ,8 °.0:28.: 81 0:28 n = ='., 8 83 - " ° ;0.27 0:27 _ 85 0 ,,-.86 026 . }, 89 90 ., :. - . ' 0:25 91-120 Note: Rates for 61-120 MPI:ohly applicable where supplemental treatment provided. to 7 : 1.04. =8:.;. - ,..: , 0.96 r 9 0.88 0 0:038 11 .78. .12, : -_?..:.: 0.77. 13 0.75 14" 0:74 _ : 15 . 0.72. _ 1,6E 0.70. :.:.._: 17 0.68 18 :: :0:67- .. ° .._ : 19 0.65 ? 6 , 2 0.63 22 7:6 23 0.6 ,.. 25 0.59 26 i :: ,.-0.59 :.4 ,. 27 0.58 29 0.57: 30 0:56 _- 31 0.55 0. 5-78 33 - 0.54:.: 3.4::.:. (, 0:53 ; ,.` 35 0.52 36 0.52.:: :, °: 37 0.51 38:: `. • :. - ' _ 0.50 _ 39 0.49 .40 ::. r. 0:49 .. "::.. ` . 41 0.48 43 0.46 44 0.46. '.:: 45 0.45 _ ........ .... .. 4 ,. . 47 0.44: 0:43. 49 0.43 54 0.59 91- Table 5. PDST Wastewater Application Rates 56 0.57 57 . 0.56 Percolation Rafe, Application Rate, MPI <(alid/ft- z 59 :0;54 'Percol_ition;Rate : Application Rate Z t, MPI 1-24 : 1.20 61 0.52 25 _ 1;19 62 0:51 _ 26 1.17 63 0.50 27 1::16 64 0.49 28 1.15 65 0.48 29 1::13 66 . 30 1.12 67 0.46. ,._31..:%i 1:09. ..,._>:.:' 68 046 32 1.06 69 0.45 1:03 34 1.00 71 0.43 0:9T _ :' 72 . 0:42 36 0.94. 73 0.41 37.`> 0:91 38 0.89 75 0.39 = 39 - �,. 0.86 X76 .. 40 0.83 77 0.37 414 0:80. _ . 78_ 0:36 42 0.77 79 0.35 . 43 .. 0:74 ;r _... _ _ .. '80 0,34 44. 0.71: 81 0.33 45 ;0:68 82 0:32 46 0.67 83 0.31 . 47 :: ° 0".66 48 0.65. 85 0.30 49 ... 064: -, ` 86 0:29 w x 50 0.63 87 0.28 -:0,62'88 0.27 52. 0.61 89 0.26 53. 0:60 >900:25. 54 0.59 91- _ 56 0.57 57 . 0.56 58 0.55 59 :0;54 60 0.53 SANTA CLARA COUNTY ONSITE SYSTEMS MANUAL - -- - -- PART 5 .-0PERA~TI0,N., MONITORING AND MAINTENANCE VA a Onsite Manual - Part 5 (9/2013) Page 1 PART OPERATION, MONITORING AND MAINTENANCE 1. OWTS. PERFORMANCE REQUIREMENTS A. GENERAL PERFORMANCE CRITERIAR` 1. All onsite wastewater treatment systems (OWTS)-shall fun'ctio a) Be sanitary and not create a health hazard or nuisance, b) Prevent backup or release of wastevater�or waste structure(s) being served..by the OWTS; c) Not discharge wastewater,o°r,wastewater effluent�i surface water, or in such a manner tlatgroundwat 2. All OWTS an the specific individual compo nditions and appl 3. All OWTS shall be "& compliant particula t tithe type�of system; the'facil B. CONVENTIONAL SYSTEMS`. r in such a manner as to: luennt into the the ground surface or into ay be adversely impacted. ll'meet the performance requirements for r which thev are aooroved. h applicable performance requirements awed, and the site conditions. 1. All septic tanks shall b&structu ally'sound, watertight, provide clarified effluent, have adequate -space available -for sludge and scum storage, operate in such a manner as to not create od rsXor vecforattraction; be properly vented, and have a functional. baffle(s).`` 2. Dispersal systems shall: (a) have adequate dispersal capacity for the structures and/or uses served, (b) not result in seepage or saturated soil conditions within 12 inches of ground surface in or adjacent to the dispersal field; and (c) be free from soil erosion or instability. 3. Effluent shall not continuously pond, at a level above the invert (bottom) of the perforated distribution pipe in the dispersal trench or serial distribution overflow line, as applicable. Onsite Manual - Part 5 (9/2013) Page 2 4. All components of the OWTS shall be functional and in proper working order. C. SUPPLEMENTAL TREATMENT In addition to meeting criteria in A and B above, supplemental -treatment systems shall comply with the following performance requirements. 1. Effluent Quality. Effluent produced by all supplemental treatment systems shall comply with the following minimum constituent limitationsf,,. *Due to proximity to public water supplywell orurface,water intake per SWRCB OWTS.Policy and Section B-1`1=6\7(1)(6), Santa Clara County Code; wherea-'pp�licable, additional requirements include: (a) minimum 3 -ft separation to groundwater below -dispersal field; and (b) minimum 12 inches of soil cover -over dispersal piping. ` 2. Sand FiltersSand filters sh ,4 _zl b \_4 .a. be operated to mainta_ in uniform effluent distribution throughout the sand filter i .bed; b. not result in continuously ponded effluent on the distribution bed infiltrative surface; c. be operated, and maintained to prevent channeling of flow, erosion of the sand media or other conditions that allow short-circuiting of effluent through the system; d. not result in leakage of effluent through the sand filter liner or supporting structure; and e. conform to applicable requirements for pressure distribution in D.1 below. Onsite Manual - Part 5 (9/2013) Page 3 (2). (3) .For Use with "wFor.,Use with Where Constituent ` Trenches and '. Drip Pathogen At -grade Dispersal Removal 'Systems Systems`\ Required* Biochemical Oxygen Demand (BO.D,), mg/L '30:< ° "f' 20 , \Per (1) or. (2)' ` `•. as applicable Total Suspended Solids (TSS), mg%L ,. •1 30 t 20 Per (1) or (2), �, as applicable Fecal Coliform; MPN/100 ml N/A \ a N/A 200 *Due to proximity to public water supplywell orurface,water intake per SWRCB OWTS.Policy and Section B-1`1=6\7(1)(6), Santa Clara County Code; wherea-'pp�licable, additional requirements include: (a) minimum 3 -ft separation to groundwater below -dispersal field; and (b) minimum 12 inches of soil cover -over dispersal piping. ` 2. Sand FiltersSand filters sh ,4 _zl b \_4 .a. be operated to mainta_ in uniform effluent distribution throughout the sand filter i .bed; b. not result in continuously ponded effluent on the distribution bed infiltrative surface; c. be operated, and maintained to prevent channeling of flow, erosion of the sand media or other conditions that allow short-circuiting of effluent through the system; d. not result in leakage of effluent through the sand filter liner or supporting structure; and e. conform to applicable requirements for pressure distribution in D.1 below. Onsite Manual - Part 5 (9/2013) Page 3 3. Proprietary Treatment Units. Proprietary treatment units shall comply with the following: a. The unit and its components shall be structurally sound, free from defects, be watertight, and not create odor or vector attraction nuisance. b. The unit shall be operated in accordance with the approved manufacturer and certification/listing organization standards. D. ALTERNATIVE DISPERSAL SYSTEMS In addition to the requirements in A and B above,aternative dispersal systems shall also comply with the following.) 1. Pressure Distribution Systems.° k'L a) .Pump tanks, risers and lids -shall be structurally sound, watertight and store wastewater effluent in's,uuch a manner as toknot create odors or vector attraction. b) Pumps, floats -,alarms and`.8sciated,controls sK be in good condition and operatein accordance with designs ecifications. N c) Dispersal field and components`shall: 1)be-9perable andifi�good condition ;3 2) maint`am uniform; distribution of effluent throughout the dispersal field; and ',3),,not result ih: continuously ponded effluent in the dispersal trench to a level above the invert (bottom) of the distribution pipe. 4) in the case of pressure -dosed sand trenches, not result in continuously. ponded,effluent above the sand interface. 2. Mound, At -Grade and Raised Sand Bed Systems. Mound; at -grade and raised sand bed systems shall: a) not result in seepage or saturated soil conditions within 12 inches of ground surface anywhere along the perimeter toe or edge of the system; b) be free from erosion, slumping or damage to the soil cover; Onsite Manual - Part'S (9/2013) Page 4 c) not result in continuously ponded effluent within the gravel distribution bed or in the sand fill (for mounds and raised sand bed systems); and d) conform to applicable requirements for pressure distribution in D.1 above. 3. Subsurface Drip Dispersal Systems. Subsurface drip dispersal systems and components shall: a) not result in seepage or saturated soil conditions above the depth of the dripline within or anywhere along the perimeter of the: dripfield. b) be free from erosion, slumping or otheraoil-disturbance that threatens to expose or cause damage to drip dispersal tubing,.or appurtenances; c) conform to applicable requirem'ents,for pressure distribution in D.1 above; and d) be operated and maintained in accordance with,manufacturer.'--, recommendations. /f-:-^_�-•mss '� � �'•-•u '�� k`'' � NI \ ki S, Onsite Manual - Part 5 (9/2013) Page 5 2. OWTS MONITORING REQUIREMENTS A. GENERAL A monitoring program will be established for each alternative OWTS as a condition of the operating permit at the time of permit issuance, and may be amended at the time of permit renewal. Said monitoring shall be performed to ensure that tt e'alternative OWTS is functioning satisfactorily to protect water quality and public-health and safety. f 4 B. MONITORING ELEMENTS The monitoring requirements will vary d typically including the following: 1. Recoding of wastewater flow=bas' elapsed time meter, in=line flow`i ing\on the specific type of,alternative system, ', � \ - I \ on water rneter'readings, pump event counter, er o\ ther appr,',.ov ed methods; 2. Measurement and recording of water levels' --in inspection/monitoring wells in the dispersal field-" -- r 3. Inspection and&ob`servation of pump operation and other mechanical equipment;. 4. Water quality,-,, selected rtiater-samples take��from points in the treatment process, from groundWater,monitoring wells, or.,.from surface streams or drainages; typical water quality parameters includet t Land fecal coliform, nitrate, BOD, and suspended solids; S. Gene'r-al. review and in'sp ction of t eatment and. dispersal area for evidence of seepage, effluensurfacing, erosion --pr other indicators of system malfunction. 6. Other monitoring,'as recommended by the system designer or equipment manufacturer. C. MONITORING FREC OENCY The required frequency of monitoring for each installation will be established in the operation permit, generally.in accordance with the following minimum schedule: • Years 1 through 4 of operation: semi-annual monitoring • Years 5 and beyond: annual monitoring Onsite Manual - Part 5(9/2013) Page 6 Monitoring frequency may be increased for larger flow OWTS (e.g., >2,500 gpd) or where warranted because of the complexity of the design or sensitive nature of the site. Monitoring frequency may be increased for any system if problems are experienced. D. MONITORING RESPONSIBILITY Monitoring of alternative OWTS shall be conducted by or under the supervision of one of the following: 1. Registered Civil Engineer; J. 2. Professional Geologist; _ as 3. Registered Environmental Health Specialist;pr rte.. ' x 4. Other onsite wastewater maintenance provider registered with the Department of Environmental Health and meeting quadfications ` as established `in this Manual. Registration shall entail: (a)�abcumentation`of required qualifications; -,(b) participation in annual training/review conducte`d,by the director; and (c) payment of an annual fee established by the Board of Supervisors'` ` N Additionally, the/,,director--may require`thirAd-party'or,..Countty inspection and monitoring of any alternative OWTS where\deemed necessary because -of special circumstances, such as the complexity of`'the\systein, {or the sensitive nature of the site. The costs for such -- additional nitorring would` berthe-.responsibility. of the owner. E. REPORTING I, � Monitoring results shall be sub'' � tted to the director in accordance with reporting guidelines provided in this Manual and.as specified in the operating permit. The monitoring report shall be signed by the party`"r-esponsib�le for the monitoring. NotWithstanding.formal monitoring reports, the director shall be notified immediately of any system problems observed during system inspection and monitoring that threaten,p�ublic health or water quality. F. POST -SEISMIC INSPECTIONS In addition to regular inspection and monitoring activities, post -seismic inspection and evaluation of alternative OWTS located in high-risk seismic areas will be required in the event of an earthquake causing significant ground shaking in the region, as determined by the director in consultation with the County geologist. The director will be responsible for Onsite. Manual - Part -5 (9/2013) Page 7 issuing appropriate notices when such inspections are required; those conducting the inspections will be required to reportthe inspection results to the director. The purpose of such inspections will be to assess and document any damage to the OWTS and to implement corrective measures, as needed, in a timely manner. Post -seismic inspection shall be in accordance with the standard inspection requirements specified in the applicable operating permit for each OWTS, along with any additional requirements that may be prescribed by the director, in consultation with the County geologist, based on the intensity, location and other aspects of the particular seismic.event.. G. DATA REVIEW, The director will, from time -to -time, compile a for alternative: OWTS and will provide a summa Central Coast Regional Water Quality ControlE Based on this review, the director may require certain types of alternative OWTS, or general c requirements.r�_ review monitoring and inspection results of results toll e,San Francisco Bay and rds at least once every five (5) years. rrectivefaction for specific properties or iges in monitoring and inspection Onsite Manual - Part 5 (9/2013) Page 8 3. OWTS PERFORMANCE EVALUATION GUIDELINES A. PURPOSE AND PERFORMANCE CRITERIA Santa Clara County. Code section B11-84 (Life extending construction) requires the completion of an OWTS inspection and r)erR changes or additions to an existing building served,Wan,OWTS,,The guidelines to be followed for such inspections. are prescribed below. -These guidelines may also be useful and employed for other: circumstances, such as:OWTS inspections in connection with -property transfers, for lending institutions, etc. { The purpose of these inspections is to -determine, on an individual basis, whether an existing OWTS is functional and meets minimum-s andards of performance established by the County of Santa Clara Department of Environmental,He`alth y(DEH). The,following performance criteria are established as minimum requirements: I. There is no surfacing effluent at anytime. 2. The effluent is not �lischarg cl-directly to groundwater; i.e., the dispersal trenches do not'extend to -or below therseasonal`high groundwater level. 3. t�There is always positive flow to the dispersal field from the septic tank, with no. backup t Fthe.tank or house,plumbingduring high groundwater conditions. 4. There is`=an adequately sized septic tank for -the structure being served and it must be serviceable e:g. accesslisers for maintenance. The septic tank must be watertight and constructed of-aoproved materials. 5. There is no indication'that the existing OWTS is adversely affecting any beneficial uses of surface water or groundwater. The following sets forth procedures for conducting performance evaluations, to assure consistency and thoroughness in verifying the functioning status of existing OWTS. Onsite Manual - Part 5 (9/2013) Page 9 / B. INSPECTION RESPONSIBILITY The inspections shall be carried out by any of the following: 1. Registered Civil Engineer 2. Professional.Geologist (also meeting the requirements of 4a or 4b below) 3. Registered Environmental Health Specialist 4. Other onsite Wastewater maintenance providers registered with DEH and having experience in the construction and/or operation of OWTS as evidenced by either of the following: (a) possession of a valid contractor's license (A, .0 36 r C-42); (b) completion of an onsite wastewater certification training course by a third party entity, such as the California Onsite Wastewater Association (COWA), National Association of Waste Transporters,(AWt), National Sanitation Foundation (NSF), or other acceptable training program.as determined by the director. Registration shall require completion of an application form, demonstrated minimum qualifications, participation=in an annual review/ training session conducted by the director, and payment of an annual fee �Registration�s hall require annual renewal. The individual conducts k,Ahe'`field inspe tion woekil`s all„wbe qualified in the operation and maintenance of OWTS.and trained'specifically'inthetesting<an`'d)inspection procedures outlined in this document. C. BACKGR ND,DATA� Prior to: conducting. theonsite`p 'performance " pection available background information pertains g,to`the property,''structuresyad septic system should be compiled and reviewed. This should include permit information, site plan, "As Built.. drawings of the OWTS, prior inspection results, etc. �' a The site plan should `show the;,location of the septic tank and dispersal, the locations of all buildings, decks, cutbanks,' eks, wells, reserve or failsafe area, direction and percentage of slope, or any other.items which may affect the OWTS. The reserve dispersal field area(s) should be identified and evaluated for any conflicting encroachment by buildings or other site development. D. INITIAL SITE RECONNAISSANCE Initially, the inspector should walk the property to confirm the location of: the septic tank, dispersal field, and other pertinent features of the system. In verifying the dispersal field Onsite Manual - Part 5 (9/2013) Page 10 location; the length of each line and the depth of the drainpipe (below ground surface) should also be determined for comparison with observed groundwater conditions. This may require probing with a metal rod or actual excavation to locate the pipe. . Site reconnaissance should also include a check of setbacks,`between the existing leach field and expansion areas and any man-made structures, e.g:; to"confirm no building foundations recently added within or too close to the existing leach field orexpansion areas. The septic tank and. dispersal field areas should be checked for any obvious signs of existing system problems such a surfacing effluent, `odors,, greywater bypasses;` selective fertility (i.e., lush vegetation in the dispersal field area) or any. other condition that may suggest an existing or impending. problem. .The inspectorshould determine -'if" system has dual dispersal fields and, if.so, locate and check the diyersion.,valve: (a)'to.see that it is functional; and (b) to \ ~�A , determine which field is in service. Alkpbservations shoA-be noted. As part of the initial site reconnaissance`a hand-augured,boring-.,(3'-inch minimum) should also be made within or (adjacent to. the dispersa)\field efor observation of soils and groundwater s` conditions. An initialhreading (Le` 'depth to groundwater from ground surface) should be taken when the boring is made``The;boring .should''then be left open for the remainder of the performance inspection so that. a -final- reading maybe taken after the water level has been allowed- llowed t9/st`abilize for about 1.,hour. The boring should be backfilled before leaving the site. If a hand -auger boring is'-.not� feasibl ?,and the area is known or estimated to have high groundwater. -conditions, a motorizeddrill'rig may be necessary. E. SEPTIC TAN KtINSPECTIOk, After the initial site reconnaissance has been conducted, the detailed inspection of the system should commence. <� 1. Access Risers First, locate the septic tank and determine if permanent access risers have been installed on the septic tank. If the tank is equipped with risers, check their general condition. Ideally, the risers should be properly grouted or sealed to the top -of the septic tank to prevent groundwater and/or surface water intrusion. The lids of the risers should also be properly sealed to prevent odors or the entry of insects, (e.g., flies, mosquitoes, etc.). Any observed defects in the access risers should be noted. If the tank lacks access risers, this information Onsite Manual - Part -5 (9/2013) Page 11 should be so noted; and the property owner should be provided information about access risers and advised to have them installed. 2. Opening the Tank After inspecting the access risers the septic tanklids should be carefully removed. Care must be taken -if gardens and shrubs -are near to prevent damage.and to disturb the yard area as little as possible. Concrete lids are heavy and may be "cemented" in place by silt. A steel bar or other suitable tool maybe needed to assist in opening the lids. During the tank inspection process, personnel should wear protective boots a_nd gloves (neoprene) to guard against infection from pathogenic organisms. 3. Structural Condition Once the tank is open, the inspector shouldobserve erve and probe\the structural condition of the septic tank to check for any obvious signsrof cracking or other'structural defects in the tank: A steel rod is used to probe the walls and bottgnm,okh'e tank. Normally,. the tank will not need to be pumped -out to per -form, -this procedure. The inlet and outlet sanitary "tees" should also be inspected to assure` -that, they a ren\ satisfactory condition, properly positioned, and free of scum accumulation'�r, cks, root matter.or other obstructions. Any problems should Fbe oted and the insptector shoo d assess `whether or not additional tests or observations are necessary to verify the structural integrity of the septic tank. 4. Liquid Level The liquidlevel-in thegank.should be, measured with respect to the outlet pipe. In a properly°"functioning,system``�thhee level in th tank should be even with the invert (i.e., bottom) of the outlet;pipe. If`t 16,1,iquid level is below the outlet pipe, the tank is probably leakin'gs4 _If.the liquid is abo a thepipe;;the dispersal field is either flooded or the line to the field is obstructed or possibly set with an improper grade. The depth of water above or below the out] pipe should be measured and noted. S. Tank Capacity The capacity of the septi_c,tank (in gallons) should be determined from as -built plans or from measurements of the width, length and .depth (below outlet pipe) of the tank. The capacity can then be compared with the established water use/wastewater flow rates for the property. Onsite Manual - Part 5 (9/2013) Page 12 F. HYDRAULIC LOAD TEST 1. General The. inspector should then proceed with the hydraulic load test of the septic tank and dispersal field. The test, as described here, is conducted only for conventional gravity -fed dispersal trench systems, and does not apply if the system utilizes a pump. A separate test to be conducted for pump systems is described in the next section. The hydraulic load test is conducted by surcharging the septic tank with about 150 gallons of water over a 20 - 30 minute period; and then observing the rise of water;=in \the tank and the subsequent draining process. Although not always conclusive, tracer -dye, added to the tank, may be used to assist in investigating the possible contribution of effluent where surface wetness/seepage is suspected or observed. A.,garde hose,dischharging into the outlet side of the tank can .be used to surcharge the tank./The hose outlershould remain at least 12 inches above the water level in the tank` toyprevent cross contain ation. Before starting the test, the flow rate from the hose should 'be determined (i.e., with 5 -gallon bucket and stop watch) to properly gauge the amount;of,�surcharge water added to the tank. Alternatively, a portable water\meter-can be installed, b tween the house faucet and the hose to directly measure the waterolume added.- 2. dded.2. Test Procedures The step -by step;procedures.for the hydraulic load,test; are _then as follows: V` Measure the location of tKe•static water line in the septic tank (at the outlet side) as an initial reference point �,•�.. �' ,' ® /Begin surcharging the tar • Observe any rise in 'the -Iii end offilling. Typically, liquid IeVel should stabili; in a matter bfminutes afi h water•to-start the hydraulic load test. uid level.,at the outlet pipe and measure the water level.at the he liquid. -level will rise from 0.5 -to 1-inch,:at which point the �lfoe the reminder of filling, and then return to the initial level >,r filling is stopped. After the filling cycle-is"finished, the water level decline in the septic tank is observed until the initial level is reached; and the time to achieve this is recorded. If the initial level is not attained within 30 minutes, the test is terminated and the final water level is noted. 3. System Rating Based upon the water level readings during the test, a hydraulic performance rating is then assigned to the system in accordance with the guidelines provided in Table 1. It should be Onsite Manual - Part5 (9/2013) Page 13 -- ' and -special circumstances be fo peoa rcunn nces n�ay cause r 'modifying the evaluation and rat ng.of a particular system. A system receiving a, "Failed" ` rating will likely require upgrading and/or additional investgation to determine the underlying cause(s). H. FINAL LEACHFIELD INSPECTION At the completion of the hydraulic load test the dispersal field area and downslope areas should be checked again for indications of surfacing effluent,,wetness,d If any of these RATING �to,.Tlc TA/NK RESPON�E HYDRAULIC LOADING EXCELLENT,", .'No notic6abl6rise in waf6r,-i'evel during filling. 'Maximum watdr level rise of about 2 inches, with decline to �Mbximum water level rise of about 3 inches, with decline to initi'ai'level within about 30 minutes after end of filling. Water level rise of more than 3 inches, with decline not reaching initial level within 30: minutes after end offilling. Water level rise of more than 3 inches, with no noticeable FAILED decline within 30 minutes after end of filling. Onsite Manual - Part 5 (9/2013) P age 14 I. PUMP SYSTEMS For systems equipped with an effluent pump, the following inspection procedures should be followed: This is in addition to inspection of the septic tank as described under "E. Septic Tank Inspection". 1. General Remove the pump access cover and basin lid, taking care that no soil or other material enters the basin. Note any signs of scum or sludge buildup, indications of previous pump failure (such as scum line above the high water alarm switch), or evidence of soil or roots r' �f entering the basin. Look for any signs of groundwater'infiltration or surface water inflow to the basin. Also, inspect the float controls to see`ihat'they,,have free movement, and check the electrical junction box (if located 'in the: -basin or access riser,) for any obvious signs of corrosion. Measure the dimensions ofith,9,;,pump basin and" -determine the amount of emergency storage capacity for comparison with the system design and County guidelines (1.5 times the daily sewage flow volume). If;the water vel in the basin is normal (i.e., between the high and low water,c ntrols) proceed aw thft sting of the pump system. 2. Pump Test , The pump testis conducted by adding sufficient -v.' to the basin to activate the pump "ON" control, and --observing, the performance;'offtF system,over at least one pumping cycle. The totallarrn nt of'weter added; sh uld'be about 150gallons,ao approximate the same hydraulic: I ad g\of thej_dtspersal, f Id for gravity systems. Using a garden hose, the water -may be added to outlet,side ofOe septic tank, or directly to the pump basin. � If filling the -basin, directly; :care should�.be taken �to minimize turbulence and disturbance of sediment or slude6that may,hAve collected,in the basin. This can be best accomplished by dir eb tinga-the stream of,water against the interior side of the chamber, rather than directly toward the_ bottom of the,pump chamber. Observe the filJngr of the basin, and note and measure the point at which the pump is activated. Immediately stop.the filling. operation and observe the pumping cycle until the pump shuts off. While the.pump is discharging, examine the piping system_ (where exposed) for any leaks. Even small -leaks could be a forewarning of possible breaks in the pressure line at some point in the future; and these. should be corrected as soon as possible. Note and measure the depth at which the pump shuts off, and calculate the volume of water between the "ON" and "OFF" measurements. Compare this dose with. the design dose volume specified for the system. If the dose is too high or too low, float controls should be readjusted to correct the dose. Any adjustments to the pump system should be done by a licensed and properly qualified contractor (not by the inspector, unless so qualified). Onsite Manual - Part.5 (9/2013) Page 15 The pumping cycle (from "ON" to "OFF') level should be timed and the:results recorded on the inspection form. Typically, if the pump is sized and operating properly, pump operation lasts about 1 to 5 minutes per dose.. Pump cycles lasting longer than this may indicate a flooded dispersal field and/or pump or piping deficiencies. If this is observed, it should be noted and further investigation of the.pump and dispersal field should be conducted to determine thespecific cause. Dividing the pump volume (in gallons) by the pump cycle time (in minutes) will give an approximate pump discharge rate (in gpm). The observed pump rate should be checked against the design requirement for the system, and any discrepancy noted. If during filling of the pump basin, the pump high liquid level control (i.e., "ON" float), disci failure, defective float switch or wiring prob competent contractor familiar with these."' be noted, communicated immediately to th'e i corrective action. _ z.l•/ nese not activate when the water reaches the itinue"the `punp test. This indicates a pump m's and will require the repair service of a of systems. The pump system failure should � : \. sident/owner, and followed up with prompt 3. Dispersal Field Inspection 7 , At the completion of the pump test, the dispersal field'are seepage in the same -manner as previously`descr-ibed fc hydraulic loading J. CLEAN UP should be checked for signs of r,'gavity-fed systems following At the completionof the OWTS inspection and testing, replace all access lids.and clean all tools before,[eavirig the site All toolstand equiprrient that come into contact with wastewater should be clearied,and disinfected with a 1:5 bleach s ution, then rinsed with fresh water; and all a `. contamindte-d.'ri�nse water should be disposed of in the septic tank. •` i 1 :r Onsite Manual - Part 5 (9/2013) Page 16 AFTER THEROOD: Septic Tank Failure During a flood or heavy rainstorm, excessive water can accumulate in leach field; leach line, or seepage: pit areas causing the septic system to become sluggish, to back up, or to stop. functioning when toilets are flushed or when other plumbing fixtures ate used. If the septic system was operating properly prior to flooding, household waste water should not overflow onto the surface of the ground ff a sewage backup occurs: When a sewage backup occurs in your residence or business, or when sewage overflows. onto the surface of the ground, the following must be done until the flooding or ground saturation dissipates: if there. is a backup or visible overflow of sewage onto the ground, immediately stop all water usage. 'Once the flooding and groundwater saturation diminishes, the septic system should again operate normally. • if the system is slow or sluggish, but still operating, minimize the amount of liquids and solids put into the system.. If you operate a food facility and experience a septic system failure: immediately contact the Department of Environmental Health at 408 918-3400 for cleanup instructions. ffOn septiciankfsabove the flood point The tank can be pumped by a permitted liquid waste hauler/pumper (see Yellow Pages under "Septic Tanks and Systems'). The septic system can be used as a holding tank and will continue to accept household wastewater and not overflow into leach lines unless.the tank is full — most septic tanks will hold up to 1,000 gallons or more (the amount of waste water per person per day from showers, dishwashing, laundry, etc.; averages 50- 100 gallons every 24 hours–a family of four would, therefore, produce 200-400 gallons each day). What ff sewage has overflowed in W house? • Wash all contaminated areas with detergent and water, then rinse with a sanitizing solution made from one tablespoon household bleach (5.25% sodium hypochlorite) to each gallon of water. (1 tablespoon = 3 teaspoons or % fluid ounce) -• Be sure to clean and sanitize all contaminated areas — pay special attention to cooking utensils, work surfaces, children's toys, and surface areas such as floors and walls which family and pets may come in contact HMO septic system is flooded or the ground is saturated so that waste water fs not accepted �/. Pumping the tank will not be effective since the flooding/saturation will fill the tank as quickly as it is pumped. V/ Use a portable chemical toilet = small units are available from camping, RV, and hardware stores. Larger chemical. toilets, such as those used at construction :sites and festivals may be rented; these units are recommended for apartments, condos, and office buildings (see Yellow Pages under "Toilets -Portable'). The functioning toilet facilities of a motorhome, travel trailer, or a neighboring home can also be used. If portable chemical toilets are unavailable, use large extra -strength trash bags ' (double bagged) as liners in toilets, or contain waste in water tight plastic or metal containers with tight fitting lids. Use household disinfectant (such as bleach) for odor control. Final disposal can be by sanitary sewer (when notified by public officials) or by burial Once flood waters have receded. Consumer Protection Oivision . Department of Environmental health . Santa Clara County. SEW-AGEDISPOSAL "AF411-10 EMERGENCY In an emergency such as a large magnitude earthquake, sewer lines will probably be damaged and become inoperable. Sewage may back up and broken water lines may become contaminated by sewage. If stoppage in sewer lines is suspected or obvious, discontinue discharge of wastewater in house or building sinks and drains, and stop flushing toilets. Avoid contact with any overflowing waste water or sewage. • Large extra -strength trash bags (double bagged) may be placed in water tight plastic or metal containers, with tight fitting lids, or used as liners in toilets. Household disinfectant can be used for odor control. Final disposal can be by burying or by sanitary sewer when notified by public officials. • A dug latrine or trench 2' to Y deep can be used to bury human waste. Spread.a thin layer of powdered lime or dry chlorine bleach and a layer of earth each time it is used. • Portable camp toilets, RV toilets, porta-potties, etc. may also be used. High occupancy complexes such as apartments, condominiums, and office buildings should consider malting arrangements to obtain commercial chemical toilets. • Wash all contaminated areas with detergent and water, then rinse with a sanitizing solution of one tablespoon household bleach (5.25% sodium hypochlorite) to each gallon of water. Be sure to clean and sanitize all contaminated areas —pay special attention to cooking utensils, work surfaces, and other surface.areas such as floors and walls with which your family and pets may come in contact. County of Santa Clara Department of Environmental Health 408-918-3400 PiMW- nePWPW- 1&6070: