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Jeanne A. Mabusth <br /> June 15, 1983 <br /> page 3 <br /> table at 4 . 5 ' , 5. 3 ' - shallow trenches - maximum trench <br /> depth 18" into original soil <br /> - Alternate site - slope 6� - mottled at 3 . 8 ' , water <br /> table at 3 .8 ' - modified shallow trenches* - maximum <br /> trench depth 10" into original soil <br /> Lot 4 Block 2 Percolation Rate Average 14 MPI both sites <br /> - Primary site - slope 7$ - mottling at 4 .4 ' , 5 . 5 ' - <br /> water table at 4 .4 ' , 5.6 ' - shallow trenches - maximum <br /> trench depth 17" into original soil <br /> � - Alternate site - slope 5� - mottling at 4 .0 ' - water <br /> table at 6 .4 ' - shallow trenches - maximum trench depth 12" <br /> into original soil . <br /> *Modified Shallow Trenches - where water table or mottling <br /> is between 3 .0 ' and 4 .0 ' below the surface, a standard <br /> 12" rock depth (6" under pipe, 2" over) must be used in <br /> conjunction with an appropriate depth of fill material <br /> to retain a 3 .0 ' separation between the bottom of trenches <br /> and the water table or mottling. Fill should consist of <br /> material ciassified as loamy sand (USDA classification) . <br /> The original soil must be dryer than the plastic limit <br /> before placing fili . The original surface must be scarified <br /> or disced to break up the surface vegetation mat. The <br /> loamy sand fill must be placed over the entire area so that <br /> no trench will be located less than 10 ' from the edge of <br /> the f ill . The depth of fill required will depend on the <br /> allowable depth of excavation into original soil based on <br /> the water table or mottling. � <br /> I recommend that the subdivision be approved as proposed. The <br /> developer should be warned to keep all traffic, fill excavation, <br /> etc. away from the tested drainfield sites. In some cases <br /> where road construction will be near the tested sites, extra <br /> caution must be taken. <br /> MPG: jl <br />