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LOGE 1607: Venice Island Ferry Tender's Residence Page 3 <br /> April 13, 2016 <br /> Percolation Test Summary <br /> Test No., Percolation Percolation Test Duration Comments <br /> Date Tested Test Rate (see notes) <br /> Depth (ft.) (minutes/inch) <br /> P1 <br /> (to the south Rapid perc. <br /> of septic 2.50 <5.0 1 hr. rate <br /> disposal pad) <br /> 4/8/16 <br /> P2 Satisfactory <br /> 4/8/16 2.45 50 4 hr. perc. rate <br /> 4/8/16 4.50 <5.0 1 hr. Raprateid erc. <br /> P4 5.75 --- 4 hr. Slow perc. rate <br /> 4/8/16 <br /> Discussion <br /> The protection of ground water is an important factor to consider when installing septic <br /> system disposal fields in shallow ground water areas. In these sites, engineered septic <br /> systems have sometimes been required by SJCEHD to mitigate potential nitrate <br /> buildups in shallow ground water. <br /> Other times, a standard filter bed or mounded septic system has been used in shallow <br /> ground water areas where satisfactory conditions allow. SJCEHD provides standard <br /> construction details in situations where filter bed systems can be used. For this site, the <br /> soil, ground water, and percolation rates were examined in detail to determine whether <br /> this site may be suitable for a standard-type SJCEHD filter bed system. <br /> The soils at the site were found to be organic (deltaic) soils composed of layers or <br /> combinations of silt, clay, or fibrous peat. The depth to ground water was found to be <br /> 13 ft below the surface. Plate 3 depicts the soil layers, ground water depth, and <br /> percolation rates encountered during this investigation. <br /> The ground water level is 13 feet below the surface and exists within an organic clay <br /> layer exhibiting slow percolation rates less than 60 min/in. These kinds of soils were <br /> observed from about 5 ft to 13 ft and typically act as a low permeable boundary <br /> restricting downward movement of septic field effluent. <br />