ARCHIVED REPORTS XR0010884 - Laserfiche WebLink

Home Browse Search

3.0 PROBLEM ASSESSMENT ' On July 3, 1995, W.W. Irwin, Inc. directed the drilling, logging, and sampling of Hydropunches'HP-7, HP-8, HP-9, and HP-10. HP-7 and HP-8 were completed as monitoring wells MW-7 and MW-8 after ground-water samples collected for "rushed" analyses of gasoline and diesel analytes at Sherwood Labs in Hilmar were found nondetectable. The new monitoring wells were drilled, sampled, and completed in order to determine the horizontal and vertical extent of soil and ground-water contamination. The new monitoring well locations are initially depicted on the Site Plan, Figure 2. 3.1 Drilling Operations Prior to the start of drilling operations, Underground Service Alert (USA) marked the locations of underground utility lines in the vicinities of the proposed borings so that the hidden conduits would be avoided during drilling activities. The required well installation permits were procured, and the SJCPHS-EHD was notified 48 hours prior to the planned drilling date. A copy of the multiple Hydropunch'/monitoring well installation permit is included as Appendix A. The borings were drilled by Mitchell Drilling & Environmental Corporation (Mitchell) (C-57 License No. 672617) of Rancho Cordova, California. Mitchell utilized a Mobile B-57, truck- mounted drilling rig equipped with 8- and 10-inch O.D., hollow-stemmed augers. All drilling equipment was thoroughly steam-cleaned prior to drilling in order to prevent contamination from t off-site sources, and also between borings to prevent cross-contamination. 3.2 Soil Sampling Undisturbed soil samples were collected at 5-foot intervals to 15 feet bsg in HP-7 and HP-8, and to 20 feet bsg in HP-9 and HP-10 during drilling operations in order to identify the soil types within the vadose (unsaturated) and capillary fringe of the water table. The samples collected at 15 and 20 feet bsg were submitted for analysis. Soil samples were logged by the W.W. Irwin, Inc. field geologist using the Unified Soil Classification System. Drilling data and the depths at which the water table was encountered were noted on all boring logs, which are included as Appendix B. The stratigraphy penetrated when advancing the borings consisted of primarily of black-gray, organic, clayey silts. Cuttings have been stockpiled on-site for later treatment and/or disposal at the discretion of Village West Marina management. The soil samples were collected by driving a two-inch diameter, California-modified split-spoon sampler utilizing a 140-pound hammer from a rig height of 30 inches (per ASTM Standard 1586). Blow counts required to obtain each sample were recorded on the respective boring logs. W.W. Invfn, Inc. Project No. 33016.05&.06 %' August 1995 6