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FDepartinent Application Permits on file with the San Joaquin County Environmental Health shows there have been four Applications for Repairs/Additions to septic systemse mile radius study area, with particular emphasis to houses on Kasson Road.ations were for additional leachline drainage or filter beds. Since the water table is 11 very shallow in this area, seepage pits or sumps are not allowed. Four septic system repairs and, n✓ additions within the study area can be considered a high number considering the extremely low)��51 Y L I i . density housing, and indicates the systems in this area have a definite lifespan. This may be f(l� f attributed to the indigenous heavy clay soil and eventual biomat formation. SOIL PROFILE AND PERCOLATION TESTING The soil from the ground surface to 5 ft is uniform and consists of a medium brown clay, with organic matter and little moisture. There is severe cracking of the soil on the surface which appears to extend downward to approximately three feet. Below 5 ft is a light tan clayey silt soil structure that extends to the water table. The Unified Soil Classification System (USCS) classifies this soil as CL (a lean clay) for the soil down to 5 ft and CL-ML (a clayey silt) for the remaining soil depth to 8 ft. A Log of Boring designating the USCS soil classifications for the percolation test borings is found near the top right-hand comer of the FIELD PERCOLATION TESTING REPORT. A Well Driller's Log for the existing domestic well (as illustrated on the Tentative Map)was not in the microfiche at the Environmental Health Department. Attached monitoring well logs for the Chevron Banta terminal facility which is approximately 2 miles to the northwest illustrates strata variations of clay, sandy clay, sand and clayey sand. Percolation testing was conducted on Parcel 1 for the septic system that will serve the office building and on Parcel 2 that will serve the house. One shallow(42 inches) perc test was done on each of the two Parcels. Perc testing was not done on the Designated Remainder, in accordance with Environmental Health Department regulations. The boring was drilled on August 19, 2001 and scarified and pre-saturated to 75% of test boring capacity on August 26,the day before testing. Readings were taken over a four-hour test period to ensure maximum soil saturation under "worst-case scenario" conditions. The perc test results exhibited comparatively rapid perc rates throughout the four-hour test period considering the high clay content soil. The final perc rate was 30 min/in for Parcel I and 6 min/in for Parcel 2. These perc rates can - probably be attributed to the clay soil cracking at the perc test depth.�L�_ (f t- Page -2- Na(!ey Ag Research