ARCHIVED REPORTS_XR0002145 - Laserfiche WebLink

Home Browse Search

groundwater monitoring well construction conformed to the standards recommended by San Joaquin County and the Regional Water Quality Control Board. The wells were completed at a depth of approximately 25 feet below grade. Well completion depths were based on setting of the well screen approximately 15 feet below the top of the saturated zone. The wells were constructed of 2 inch diameter F480 threaded FVC screen/casing. No glues or solvents were used. Screen slot size is 0.010 inch. Sand pack material is 2/12 pre- washed silica sand. A 1-1 1/2 foot bentonite seal was Placed prior Lo grouting with a cement/sand slurry. A field- prepared cement/sand slurry was prepared at the direction of the San Joaquin Count; staff inspector, Actual completion depths were determined in the field based upon hydrologic conditions encountered. Actual well, construction is shown on well/boring logs contained in Appendix II . 3.2 Soil sampling Drill cuttings were logged continuously for characterization of contamination and soil type by an experienced staff civil engineer using the Unified Soil Classification System. Descriptions of soils encountered are presented on the well/boring logs in Appendix II . Soil samples were collected from each boring at f+ve foot inte_vals to groundwater. Sampie collection began at a depth of five feet. Soil samples submitted for analysis were selected based on obvious signs of contamination (i.e. soil discoloration or odor) . Samples were collected, preserved, and transported under chair,-of-custody in accordance with WaterWork' s Soil Sampling Protocol (Appendix III. Two samples were collected from monitor well one (MW1 ) and three (MW3 ), but only one was collected from monitor well two (MW2) due to the second sample being saturated. Detection limits for TPHG a--e 30 ppm, and for BTEX they are 0.30 ppm. A representative sample from each five foot sample was tested, with the photoaonization detector, for total organic vapors (Table 3) . }Drill cutting, were placed in the contaminated soil pile underlain by and covered with v.isqui.ne. Contaminated soils will be disposed in an appropriate manner after review of analytical results and obtaining agency approvals. 3.3 Groundwater sampling After allowing .rater levels to stabilize f-)r over 24 hours, groundwater was monitored in accordance with WaterWorks QA/QC plan (Appendix III ) . A survey mark tied to a common datum was established on each wellhead for determining groundwater gradient direction Surveyi+ g was performed 3