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• I [3] SOIL PROFILE AND PERCOLATION TESTING The on-site soil consists of a black organic clay surface soil which extends to an approximate depth of two feet where a light brown silty clay soil is encountered. This material extends to six feet below grade. Well Driller's Logs on file at the Environmental Health Department have been included in this report. These well logs illustrate the subsurface soil formations and are accurate since they were used for monitoring well installations. From these logs, it can be noted that there is tremendous variability in the strata of clays,silts and sands which exist under this locale. Sand strata at different elevations also indicate intermittent, confined aquifers. Two percolation tests were conducted on March 24,2000 in the areas denoted on the Plot Map. The perc test procedures were done according to San Joaquin County Department of Environmental Health and E.P.A. regulations. The Field Test Data Sheet with the perc test results can be found in the Appendix. The first perc test,denoted 1-PERC,is the rate obtained in the unsaturated zone at a typical leachline depth of 42 inches. As can be seen,as the soil became increasingly saturated,the perc rate decreased by 66% over the four-hour test period and was marginally acceptable. The second perc test, denoted 2-SAT, are the results of testing within the saturated zone. This is more a measurement of the hydraulic conductivity of this zone than of soil percolation. Test results reveal that the saturated zone will accept water readily which indicates the potential for a comparatively high rate of groundwater flow. [4] LOCAL GROUNDWATER AND SURFACE WATER INFORMATION On March 9,2000,the static water table depth was measured by sounding the on-site well and found to be 5.5 feet below existing grade. The 1998 "Lines of Equal Depth"published by the San Joaquin County Flood Control District does not denote a standing water table depth. A hand-boring on March 8, 2000 in the location of the percolation tests revealed the static groundwater depth to be approximately 4.5 feet below grade. The capillary fringe was encountered at five feet with the zone of saturation occurring at six feet, where the boring was terminated. The two-foot rise in groundwater elevation from the zone of saturation at six feet to the static water level indicates the top groundwater is confined and under pressure. This would be expected given the heavy clay soil above the zone of saturation and the fine soil texture of this zone. A perched water table condition does not exist under the subject property at a higher elevation than the static water level. There appears to be no potential for septic impact to any surface waters, such as irrigation or storm water. According to the attached groundwater"Lines of Equal Elevation"map published in 1992, the groundwater directional flow travels in a north-northeast direction. 2 Valley Ag research