SU0007116 SSNL - Laserfiche WebLink

Home Browse Search

Well Drillers' Logs for two nearby domestic wells were found in the microfiche files at EHD. The underground lithology surrounding the subject property appears to consist of sand, clay and ravel. There appears to be a significant clay strata from 60 to 70 feet and past 100 feet. The property is in Flood Zone C and not subject to 100-year flooding, which is based on Wong Engineers' determination. Surface water runoff from the homesite Parcel is diverted into the surrounding almond orchard. (§ 4.3 and 4.5) The old and new on-site domestic wells are adjacent to North Ripon Road, near the residential structure. Before the new well was drilled 25 feet east of the old well, the old well was sampled on September 25, 2008. The pump on this well was operated for 15 minutes to insure that well casing water and tank water had been purged. A nitrate water sample was drawn into a one-half liter plastic bottle and the DBCP sample was drawn into three VOC glass vials. After the new well was drilled, a water sampled was obtained under the same sampling protocol on November 10, 2008. (§ 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 Chains of Custod found in Appendix B. (§ 4.4) Water an Its rye. igh nitrate con ntrations in both t e old a new domestic wells at 69 ppm a r60 ppm, he Maximum Contami t Leve CL) for nitrate in drinks r ismT" BCP was also found to be present in both wells, but below the",CL. A summary of the test results are illustrated in Table 2, below. (yjyp/Na�x ,ppltlMu 0,aW (§ 4.2) Considering the area has been intensely farmed for the past several decades, these nitrate concentrations may be expected in the two tested wells. The decrease in nitrate concentration within the deeper new well shows that downward migration of nitrate is being impeded. However, conversely, the DBCP concentration increased by a factor of 3x between the shallow old well at approximately 63 feet in depth and the new well at approximately 215 feet in depth. TABLE 2 ORIGINAL OLD AND CURRENT NEW WELL WATER ANALYSIS EDomestic ANALYTE CONCENTRATION MAXIMUM CONTAMINANT LEVEI, FOUND Nitrate(As Nitrate) 169 ppm 45 ppm ell DBCP 0.044µ/L 0.2µ/L NEW Nitrate(As Nitrate) 60 ppm 45 ppm Domestic Well DBCP 0.12 1,1/1. 0.2µ./L. Page -4- Chesney Consulting