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After drilling, two inches of fine gravel was placed at the bottom and three-inch perforated PVC pipe was inserted in each test boring. The borings were pre-saturated with 12 inches of water at 1000 hrs, February 24, 24 hrs before the start of pert testing. SSS§ 6.4, 6.5. On February 25, 2008, percolation testing commenced. No standing water was observed after the 24-hr soak period in either shallow boring. Consequently, EHD Perc Test Procedure 42 was conducted. Testing was done over four hours to induce maximum soil saturation, although because of recent rains, the soil was already very moist. G ` The test results indicate a very slow (failed) percolation rate for the 36 inch test boring, and a relatively rapid Perc rate for the 42 inch test boring. A summary of the Perc test results and related data, with corresponding application rate in gallons of effluent accepted per square foot of soil, per day are found in Table 2: ` TABLE 2 PERCOLATION TEST RESULTS AND RELATED DATA SHALLOW PERC TEST POST SOAK PERC TEST RESULTS APPLICATION RATE IN DEEP PERC TEST PERIOD GALLONS/FV/DAY G �J No Standing 83.3 min/in(FAIL) 0.235 gals/sq ft/day 36 INCHES Water in Hole 42 INCHES No Standing 13.2 min/in 0.757 gals/sq ft/day Water in Hole Application Rates adapted from: Calif—Wa.State GValer Resources•Control Board Guidelinesjou the Desigx of Sewage.5`i.slenrs. � D. GROUNDWATER INFORMATION L l� NLS§ 2.1, SSS§ 4.1. Groundwater depths and elevations throughout San Joaquin County are illustrated on maps published by the County Flood Control and Water Conservation District. The most recent Lines of Equal Depth map indicates the groundwater depth to be approximately 85 feet. The 2003 Lines of Equal Elevation Map illustrates the groundwater directional flow to be generally in a southerly direction. Nearby well logs illustrates varied geological strata of clay, sand and gravel. Groundwater research in the scientific literature suggests there may be significant denitrification potential within aquifers or saturated zones composed of a fine clay soil fraction. NLS§ 2.2, 3.1, SSS§ 2.1, 4.2. Since surrounding properties have been intensely farmed for several r . decades, the potential for nitrate contamination in the underlying shallow groundwater aquifers can be considered significant for shallow wells. It is unknown how deep the on-site well is, but it is assumed to be deep. The required analyses are found in Appendix D, and summarized below in r Table 3. The nitrate and DBCP concentrations in the well water indicate a 12 ppm nitrate (as nitrate) and no DBCP. This may be attributed to sufficient intervening clay layers attenuating the downward migration of nitrate and DBCP, and sufficient denitrification potential within the underlying aquifers, as referenced above. 4 �jj Chesney Consulting I