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FCNoell Driller's Logs for any nearby domestic wells were available to illustrate the underlying thology. Perched water table conditions probably cannot exist at higher elevations than the water table since the water table is at a comparatively shallow depth of 28 feet. This static water table depth was measured in the on-site domestic well, which is approximately 80 feet deep. There is no potential for future septic impact to surface waters, provided that for any future systems, applicable distance requirements are followed. There is virtually no possibility of the surfacing of effluent from inundated conditions caused by flooding since the land surface slope and the high degree of porosity of the soil should allow for adequate drainage. A sample from the domestic well on parcel 2 was tested for both nitrate and the agrichemicals DBCP/EDB. Nitrate test results show a concentration of 53 ppm as NO3. The Maximum Contaminant Level (MCL) for NO3 in drinking water is 45 ppm. Considering the intensely farmed land upgradient to this domestic well over the past 60 years, a higher nitrate concentration than 53 ppm would have been expected. Nitrate impact to the shallower aquifers and significantly lower nitrate concentrations in the deeper aquifers is observed often throughout San Joaquin County. The agrichemicals DBCP and EDB were below detection limits (BDL), which is equivalent to non-detect (ND). The depth of the grout seal for the proposed domestic well for parcel 3 will be determined by EHD. Due to proximity to the Tracy Army Depot, a 200 foot grout seal has been required of wells installed within a four mile radius in the past. The domestic well proposed for parcel 3 can be considered one mile cross gradient to the contaminant plume originating from Tracy Army Depot. It is our understanding from information on domestic wells drilled in this locale, that an excellent water quality strata or aquifer exists at approximately 180 feet. If a 200 foot grout seal is required, the seal may impinge upon this strata. CONCLUSIONS The perc test result for Parcels 1, 2 and 3 suggests excellent percolation of septic effluent is to be expected at the maximum and typical leachline depth of 42 inches. As stated by the Mattos's, there have been no problems with the two septic systems on parcel 2. The shallow perc test depth also reveals sufficient distance for "treatment" of septic effluent before it encounters the groundwater table. This distance is normally regarded to be five feet. It was also evident from the perc test that percolative capacity does not necessarily decrease with soil saturation. The leachlines for the new septic system proposed for Randy Mattos's house may be installed high in elevation since the building pad will be raised to prevent flood water inundation. This will take advantage of the indigenous clay soils found in the upper surface soils and possibly enhance the denitrification process and take advantage of evaporative and evapotranspiration capacity during favorable weather throughout the year. The new system must have a 50% standby replacement area incorporated into the design and all related septic system structures Page -3- Chesney Consufting