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( The backfilled trench should be well tamped and be 'over--filled with 4 inches to 8 inches of earth to prevent depressions due to settling of earth (trench line depressions may collect storm water, leading to premature saturation of the absorption field and possibly to trench washouts). Trucks and heavy grading equipment shall be excluded from the disposal area unless special provision is made • to support the weight. •See Figure 2. Sections of disposal fields located on hillsides at different elevations shall be separated by undisturbed earth dams at least 2 feet across at the ground surface. There shall be a pipe transfer from the .terminus of the trench at one elevation to the inlet of the ztrench at a lower elevation. Section connecting lines or pipe transfers shall be 4-inch tight-joint sewers with connections to the distribution tiles in ,adjacent sections or to:a-drop box. The crown of the transfer shall be at least 2 inches •• below the top of the gravel. Transsfe-r.--lines•shall be so constructed as to insure an undisturbed �l block of earth between sections. The trench connecting the transfer =pipe and the preceding asborption section shall be dug no deeper • than the top of the soil gravel interface. The transfer line shall rest on undisturbed earth and backfill shall be carefully tamped. Inspection. wells consisting of four inch pipe placed vertically • in 'the trench from the bottom to the surface of the ground and provided with a cap or plug shall be placed at the terminus of each trench or/and at such other points as will make possible a check of the water table elevation within the trench at the inspection well points. These sampling wells shall be adequately marked to permit ready location and provide protection from damage. 3. Dosing Chamber: The dosing chamber where employed shall be constructed . of concrete or masonry units and may be an independent structure or a third compartment of the septic tank structure. It -shall have smooth finished walls and bottom at least 4 inches thick. When concrete block or other than approved interlocking blocks or masonry units are used, • -4- •