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i <br /> i <br /> f <br /> WHITE FENCE ESTATES <br /> Page No. 3 <br /> V. GROUND WATER DEPTH AND TESTING <br /> According to the San Joaquin County Flood Control and Water <br /> Conservation District ground water depth map, Spring 94, ground <br /> water in the area is between 75 and 85 feet. There is a domestic <br /> water well near the existing house on the subject property, but at <br /> the time of our field work the well was not operational. <br /> Consequently, a water sample was obtained on May 2, 1995 from the <br /> neighbor's well (Hanes) , which is located adjacent to the east side <br /> of the property. The sample was submitted to the laboratory and <br /> tested for the presence of dibromochloropropane (DBCP) and nitrate. <br /> A copy of the test results is contained in the appendix. Test <br /> results indicate that DBCP was not detected and the level of <br /> nitrate was 11 mg/L, which is well below the Maximum Contamination <br /> Level (MCL) of 45 mg/L. <br /> VI. NITRATE LOADING STUDY <br /> A nitrate loading study was performed by using a mass balance <br /> equation to obtain a simplified prediction of groundwater nitrate <br /> buildup from the proposed installation of septic systems. <br /> Assumptions that were made and calculations are contained in the <br /> appendix. Due to the cemented surface soils it was assumed that <br /> ground water recharge was from lateral movement of ground water <br /> rather them deep percolation of rainwater. Using a background <br /> level of 11 mg/1 for ground water nitrate, conservatively assuming <br /> 100 percent deep disposal of sewage effluent (dry wells) , and the <br /> proposed 1. 94 acre lot density, a resultant average ground water <br /> nitrate level of 12 . 8 mg/1 was obtained. This level is well within <br /> acceptable limits. This calculations also conservatively assumes <br /> that all effluent percolates to the ground water depth of , <br /> approximately 80 feet, which based on the soil profile encountered <br /> in the test holes, is likely not the case. <br /> VII. SOIL PROFILE AND PERCOLATION TESTS <br /> Test pits were previously excavated for our geotechnical <br /> investigation at the site. Cemented soils (hardpan) were <br /> encountered in the test pits at an average depth of 2 feet <br /> throughout the site. The cemented soils have a very low <br /> permeability. It was obvious that shallow percolation tests would <br /> not meet minimum requirements. Consequently deep pit percolation <br /> tests were performed on each of the proposed lots. <br /> =IDE. RS0 <br /> a <br /> � w <br /> P <br /> 4ssoc <br />