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ENCOUNTERED DEPTH TO WATER TABLE AND SOIL MORPHOLOGY <br />FROM THE BACKHOE TEST PIT <br />In compliance with the request ofEHD Unit II Supervisory Staff,a John Deere extend-a-hoe <br />backhoe was used to determine the depth to the water table on the morning of the percolation <br />testing,August 8,2007.After stabilizing for two hours,a depth determination of9.5 feet below <br />existing grade was measured with an electronic water level meter.This depth determination was <br />conducted at the time of the year when the water table can be considered at its theoretical highest <br />due to irrigation recharge.Additionally,the observed water table depth of 9.5 feet allows the <br />installation of a shallow,conventionalleachfield system (9.5 feet minus 3.0 feet (max.leachline depthj] <br />=6.5 feet separation distance between the water table and the soil-effluent interface.The <br />minimum separation distance is five feet. <br />Soil characteristics observed in the backhoe test pit are described using the Unified Soil <br />Classification System (USCS).The surface soil characteristics underlying the property in the area <br />of drilling reveal the soil to be predominately a lean,dark,organic silty clay (ML-CLlOM) <br />containing a fine sand (SM)from the surface down to two feet.Organic matter decomposition <br />from past cropping patterns is probably responsible for the dark soil.Below this stratum,is a light <br />brown clayey silt with a fair degree of permeability,as determined by the perc tests.No cemented <br />silts hardpan and claypan was encountered down to the total backhoe test pit depth of 10 feet. <br />PERCOLATION TESTING <br />Two shallow perc test borings were hand-drilled to 42 inches and 36 inches in depth for two <br />reasons.First,any permeability discrepancies at these two depths would be observed.Test results <br />indicate no changes in the soil strata at these depths.Secondly,these two tests were situated 105 <br />feet from the two aforementioned ag wells so that the two perc tests would cover the entire area <br />between the two wells for the installation of the four septic systems.These 100-foot radius lines <br />are depicted on the Site Plan Schematic. <br />After drilling the two shallow perc test borings,the sidewalls were scored with a pry-bar and the <br />loose material removed.Two inches of pea gravel was placed at the bottom of each boring to <br />prevent scour and three-inch perforated PYC pipe was inserted in both test borings.The test <br />borings were pre-saturated on August 7,2007 at 0800 hrs with 12 inches of clear water in <br />accordance with EHD regulations. <br />On August 8,2007,0800 hrs,percolation testing commenced.Post-soak status for each test boring <br />is illustrated in the Table below.Since no standing water was measured in the test borings,EHD <br />Perc Test Procedure #2 was conducted. <br />The last half hour of the four-hour tests,and the water table depth determination in the backhoe <br />test pit was witnessed by Ted Tasiopoulos,R.E.H.S.of the San Joaquin County Environmental <br />Health Department.The following Table summarizes the relevant data and perc test results at the <br />perc test depths: <br />Page -2- <br />Chesney Consulting