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i r(§ 4.0) LOCAL GROUNDWATER AND SURFACE WATER INFORMATION (§ 4.1) The 1999 Lines of Equal Depth Map and the 2003 Lines of Equal Elevation Map published by the San Joaquin County Flood Control do not illustrate the groundwater depths in this location of San Joaquin County due to the large variability in depths for this region. Typically, groundwater flow direction follows the topography of the land. According to the USGS Topographical map, the flow direction is theoretically in a northeast direction. It is anticipated that static groundwater is found approxima e�y 60 fe under the property. This is based upon groundwater studies done in the locale of the subs ct perty, specifically on Grant j Line Road. The groundwater elevation was found to be 10 feet below grade at the 50-foot MSL contour line on Grant Line Road, thus making the groundwater elevation 40 feet MSL. The subject property well is at approximately 100 feet MSL, thus making the groundwater elevation 60 feet MSL. Well Drillers' Logs for nearby domestic wells were found in the microfiche files at EHD. The underlying soil lithology consists of alternating strata of sands, clays and silts. i It is my understanding the property is not subject to 100-year flooding, but this final determination will be made by the Land Surveyor for the project, Mr. Chris Johnson, PLS. (§4.3 and 4.5) As referenced, there is one well on the subject property. This well was allowed to pump water for 15 minutes to ensure the sampling of aquifer formation water,with the pump cycling 5 times. The sample wast the hose bibb at the synth e of the house, near the door. This sample was analyzed fo nitrate d the agrichemidyal DBCP. clear plastic bottle was used for the nitrate samples and thr e amb VOC bottles with reservati a were used for the DBCP samples. ' (§ 4.6) 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, and the agrichemical Dibromochloropropane (DBCP). and ) The well water analysis reveals a very hfitrate-NO3) concentration 106 ppm r the domestic well. DBCP were found ton-Detect The Maximum C t Level (MCL) for nitrate in drinking water is 45 ppm. 3 nitrate concentration may be attributed to: 1.) Nitrate concentrations that have percolated down to the deeper aquifers from upgradient agricultural fertilizers, 2.) There may be thin intervening clay soil strata below this locale,which may not attenuate downward nitrate movement, 3.) There is significant gravel strata underlying the region which is allowing nitrification and high nitrate impact to the underlying aquifers, especially at the shallower depths, or 4.) Surrounding septic systems density may be causing the high nitrate. Septic system density could be considered somewhat implausible because most of the on-site septic systems in this locale are theoretically crossgradient or downgradient to the subject property. Page-4- Chesney Consulting