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(§ 4.0) LOCAL GROUNDWATER AND SURFACE WATER INFORMATION (§ 4.1) The 1999 Lines of Equal Depth Map published by the San Joaquin County Flood Control LA illustrates the groundwater depth to be 70 feet below ground surface(b.g.s.). The 1999 Lines of Equal Elevation Map illustrates the groundwater elevation to be a uniform flow in a northwesterly direction. Two Well Drillers' Logs were found for nearby domestic wells. Underground lithology specific to the subject property cannot be discerned from these logs; however, they do show intervening iL,ti strata of various clay types, sand and gravel. The property is not subject to 100-year flooding. Surface water will be managed by on-site retention basins. (§ 4.3 and 4.5) The domestic well that serves the Frost's residence was sampled from the sink , 'a faucet located in the shed which houses the well. The well pumped for 15 minutes to ensure the sampling of aquifer formation water. (§4.6) A clear plastic bottle was used for the nitrate sample and two amber VOC bottles with preservative were used for the DBCP/EDB samples. The samples were placed in a cooled ice chest and transported under the attached Chain of Custody to A&L Labs in Modesto, California to be analyzed for nitrate, Dibromochloropropane (DBCP), and Ethylene Dibromide (EDB). (§ 4.2 and 4.4) Water analysis reveals a very high nitrate (as nitrate -NO3) concentration of 133 ppm. DBCP and EDB were found to be Below Detectible Limits (BDL). The Maximum Contaminant Level (MCL) for nitrate in drinking water is 45 ppm. This 133 ppm nitrate concentration may be attributed to: 1.) A medium depth to groundwater, 2.) The domestic well 1`( may be shallow (no well log was available), 3.) The property was a dairy for many years prior to purchase by the Frost's, 4.) There may be no, or thin intervening clay soil strata under the well, 3.) Surrounding agricultural production land may be contributing nitrate. (§ 7.0) CONCLUSIONS The perc test results for proposed Parcel 1 and Parcel 2 show acceptable percolation for the management of septic system effluent flows. For these two Parcels, effluent management will occur at the deeper depths representative of sumps, or preferably seepage pits. It will be the determination of E14D to install a deep sump to be excavated with an "extend-a-hoe" in the test locations, or to drill seepage pits to the typical depth of 25 feet. As noted for the shallow tests on the two Parcels, there will be virtually no effluent percolation at the typical leachline depth of 42 inches due to restrictive clay soils and severe cemented silts hardpan. When the soil becomes saturated,percolation will cease and the sumps or seepage pits will manage the effluent flows. As referenced, Infiltrator Chambers should be considered for installation, instead of typical leachlines. Chambers may allow for greater evaporation of effluent from the soil surface. Page-4- Chesney Consulting