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(§ 4.0) LOCAL GROUNDWATER AND SURFACE WATER INFORMATION (§4.1) The 2001 Lines of Equal Depth Map published by the San Joaquin County Flood Control illustrates groundwater depths throughout the County. The map shows the groundwater depth under the subject property to be approximately 105 ft. Written information on the pressure tank from the pump installers indicates the water depth to be approximately 125 ft. Consequently, it appears the water table depth has dropped around 20 ft over the past nine years. The groundwater directional flow is most likely iin a south-southwesterly direction toward the Calaveras River. A Well Drillers' Log for the on-site domestic well was not available. Logs viewed in the microfiche files at EHD for other nearby wells reveal underlying sand, clay and gravel strata. Sanguinetti &Associates determination reveals the property is in Flood Zone C and not subject to 100-year flooding. Surface water runoff from the homesite Parcel is diverted into the surrounding cherry orchard. (§4.3 and 4.5) Located to the southwest of the main residential structure, is the on-site domestic well. The water sample was retrieved from the hose b.ibb at the south entrance to the primary residential � '0 structure. The well pump was operated for 30 minutes to insure that well casing water(which is a significant volume), pressure tank water, and water in the piping had been purged and that aquifer formation water was being sampled. A nitrate water sample was drawn into a one-quarter liter plastic bottle and the DBCP sample was drawn into three VOC glass vials with preservative. (§4.5 and 4.6) All samples were placed in a cooled ice chest and transported to A&L Labs in Modesto under the attached Chain of Custody found in Appendix B. (§4.4) Water analysis results reveal a very low nitrate concentration in the domestic well water at 6 ppm. The Maximum Contaminant Level (MCL)for nitrate in drinking water is 45 ppm. DBCP was found to be (414) Below Detectable Limits(BDL). A summary ofthe'test results are illustrated in Table 2, below. (§4.2) Considering the region has been intensely farmed for the past several decades, higher nitrate concentrations would have been expected in the domestic well. Typically,EHD prefers that any on-site irrigation wells be sampled and tested for nitrate in addition to on-site domestic wells. Unfortunately,the aforementioned irrigation well is nonoperational. It will be repaired before the start of next irrigation r/ season. The low nitrate concentration within the domestic well water shows that downward migration of (r'� nitrate 1.).Is being impeded by intervening clay strata, 2.)Just hasn't reached the water table yet, or 3.)Is diluted by inflow from the adjacent Calaveras River. TABLE 2 WELL WATER ANALYSIS WELL ANALYTE CONCENTRATION MAXIMUM CONTAMINANT FOUND LEVEL(MCL) On-Site Nitrate(As Nitrate) 6 ppm 45 ppm Domestic l Well.Sampled from Hose Bibb at South Dibromochloropropane BDL 0.2 p/L Side Entrance DBCP to House Page -4- Chesney Consulting 4