SU0008976 SSNL - Laserfiche WebLink

Home Browse Search

(§ 4.4) LOCAL GROUNDWATER AND SURFACE WATER INFORMATION (§ 4.1) The Spring 2011 Lines of Equal Depth Map published by the San Joaquin County Flood Control District illustrates groundwater depths throughout the County. The map found in . Appendix D, shows the groundwater depth in the location of the property to be approximately 35 ft below grade. The Spring 2011 Lines of Equal Elevation Map, also found in Appendix D, shows the groundwater directional flow to be in a northeasterly direction toward the San Joaquin River. A Well Drillers' Log for the on-site domestic well was not available. Logs for two nearby domestic wells on Durham Ferry Road were found in the microfiche files at EHD. The regional underground lithology consists predominately of clay and gravel. There appears to be a significant clay strata from 62 to 123 feet. The property is in Flood Zone C and not subject to 100-year flooding, which is based on Schack & Company's determination. Surface water runoff from the homesite Parcel is diverted into the surrounding cropland. (§ 4.3 and 4.5) The on-site domestic well is located to the south of the residential structure. The water sample for this Study was retrieved from the hose bibb on the east side of the residential structure. The well pump operated for 20 minutes prior to sampling to insure that well casing water, pressure tank water, and water in the piping had been purged, and that aquifer formation f water was sampled. A nitrate water sample was drawn into a one-quarter liter plastic bottle and the DBCP sample was drawn into two VOC glass vials with preservative. (§ 4.5 and 4.6) All samples were placed in a cooled ice chest and transported to FGL Labs in Stockton under the Chain of Custody found in Appendix B. (§ 4.4) Water analysis test results reveal a high nitrate (as nitrate) concentration in the domestic well at 52.8 ppm. The Maximum Contaminant Level (MCL) for nitrate in drinking water is 45 ppm. DBCP was Non-Detect (ND). A summary of the test results are illustrated in Table 3, below. (§ 4.2) Considering the area has been intensely farmed for the past several decades, this nitrate concentration would be expected in domestic.wells in this locale. It is known that deeper wells in this location have lower nitrate levels which shows the downward migration of nitrate may be impeded by the aforementioned clay stratum. TABLE 3 WELL WATER ANALYSIS WELL ANALYTE CONCENTRATION MAXIMUM CONTAMINANT FOUNDS LEVEL(MCL) On-site Nitrate,(As Nitrate) 52.8 ppm 45 ppm Domestic Well Sampled from Hose Bibb onDibrornochloropropane LD 0.2 /t East Side of DBCP µ House. - Page -4- Chesney Consulting