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rF2ndSOIL PROFILE AND PERCOLATION TESTING silt. m 0 inches to 42 inches is uniform and consists of a dark brown clay, with little sand re is significant organic matter, and high moisture content from recent rains within the soil profile. The Unified Soil Classification System (USCS) classifies this soil as CL/CH: a lean-to-fat (high plasticity) clay. A Log of Boring designating the USCS soil classification for the percolation test boring is found near the top right-hand corner of the FIELD PERCOLATION TESTING REPORT. A Well Driller's Log for any nearby domestic wells were not available, but a new well and septic system permit is attached for the adjacent residence at 28809 Mancuso Road, which indicates a clay stratum from 34 to 42 ft and sand from 42 to 95 ft. Percolation testing was conducted on Parcel "I" on the south side of the house at the extreme east end of the existing leachfield. This location theoretically gave the best data for future percolation of septic effluent. A shallow(42 inches)perc test was done because of the high groundwater elevation at approximately 8 ft. Pere testing was not done on the Designated Remainder, in accordance with Environmental Health Department regulations. The boring was drilled, scarified and pre-saturated on November 18, the day before testing. Scarification of the boring sidewalls was extremely important. Readings were taken over a four-hour test period to ensure maximum soil saturation under "worst-case scenario" conditions. The perc test exhibited poor percolation, which was to be expected given the indigenous clay soils. Without soil scarification, the perc test results would almost certainly be zero. The final perc rate for the last 30 minutes of the four-hour test was 125 min/in, and was witnessed by Mike Huggins of the San Joaquin County Environmental Health Department. LOCAL GROUNDWATER AND SURFACE WATER INFORMATION The 1992 Lines of Equal Elevation Map published by the San Joaquin County Flood Control District is the only recent groundwater map available that illustrates the groundwater elevation in this area, and therefore the directional flow. It appears, and is generally accepted, that the groundwater is flowing in a northeast direction, toward the San Joaquin River. Perched water table conditions cannot exist at higher elevations than the static water table since the water table is so shallow. There is no potential for future septic impact to surface waters, provided that for any future systems, applicable distance requirements are followed. There is the possibility of the surfacing of effluent from inundated conditions caused by flooding, as previously referenced. Analysis of water obtained from the Pombo's domestic well reveals a comparatively low nitrate concentration at 5 ppm nitrate(as NO3). The Maximum Contaminant Level (MCL) for NO3 in Page-2- Va!!ey Ag Research