ARCHIVED REPORTS_XR0009569 - Laserfiche WebLink

Home Browse Search

KEI-P89-1104 .R7 December 10, 1990 Page 10 extends to depths below grade of about 53 . 5 to 68 . 5 feet and varying in thickness from about 13.5 to 27.5 feet. This fine- grained sequence is inturn underlain by a second sandy zone consisting predominantly of silt sand and extending to the maximum depths explored in all wells (69 to 75 feet) . Ground water was encountered during drilling in this deeper silty sand zone only in well MW2 and was encountered approximately 2 .5 feet above the silty sand zone in wells MW1 and MW3 and approximately 9 feet above the silty sand zone in MW4 , generally within silt materials. DISCUSSION AND RECOMMENDATIONS Based on the analytical results, KEI recommends implementation of a monitoring and sampling program. The wells should be monitored on a monthly basis, and should be purged and sampled on a quarterly basis. The proposed program should be conducted for a period of 12 months. The results of the monitoring program will be documented and evaluated after each monitoring and sampling event. Recommen- dations for altering or terminating the program will be made as needed. In addition, the existing abandoned water well will be destroyed as soon as the special tools required by the drilling consultant are constructed. DISTRIBUTION A copy of this report should be sent to Mr. Harlin Knoll of the SJCPHS, and to the RWQCB, Central Valley Region. LIMITATIONS Soil deposits and rock formations may vary in thickness, lithology, saturation, strength and other properties across any site. In addition, environmental changes, either naturally-occurring or art if icially-induced, may cause changes in ground water levels and flow paths, thereby changing the extent and concentration of any contaminants. Our studies assume that the field and laboratory data are reasonably representative of the site as a whole, and assume that subsurface conditions are reasonably conducive to interpolation and extrapolation.