ARCHIVED REPORTS XR0010082 - Laserfiche WebLink

Home Browse Search

I construction were pursuant to standards recommended by San Joa- quin County, the State Department of Water Resources and the Regional. Water Quality Control Board (RWQCB) . The wells were completed to a depth of approximately 25 feet below grade. Well completion depth was based on placement of the screened interval five feet above and fifteen feet below the M. static water Mable without penetration of any stratum of five continuous feet of relatively impermeable material encountered below the zone of saturation. The well was constructed of 2 inch diameter F480 threaded PVC screen/casing. No glues or solvents were used. Screen slot size is 0.010 inch. Sand pack material is No. 2/12 pre-washed silica �. sand. A minimum two foot bentonite seal was placed prior to grouting with a 1:1 cement-sand grout. Actual completion depths " and construction details were determined in the field based on , hydrogeologic conditions encountered and are shown on well/boring logs contained in ,Appendix 11. Drill cuttings were lagged continuously for characterization of ` contamination and soil type by an experienced staff geologist using the Unified Soil Classification System. Descriptions of soils encountered are recorded on boring/well logs and included � in Appendix II. Soil samples were collected from each boring at five foot intervals. The samples were collected using a two-inch � diameter by 18-inch long split spoon sampler lined with 6-inch long thin-walled brass tubes. The sampler was driven its entire length into undisturbed soil by a 140-pound drop hammer. Sample collection began at a depth of five feet. No samples were col- lected for laboratory analysis below the water table which was encountered at 10 feet below grade. Soil samples collected at 6 feet were submitted for laboratory analysis, due to their posi- tion above the capillary fringe. Samples were collected , preserved, and traiisported under chain-of-custody in accordance with WaterWork's Quality Assur- ance/Quality Control (QA/QC) Plan (Appendix III) . The samples were analyzed for benzene, toluenes, sthylbenzene, and xylenes (BTEX ) and total petroleum hydrocarbons as diesel (TPHD) by appropriate EPA and DHS methods. Applied Analytical (DHS certi- fication No. 1211 ) performed the analyse ;. Soil cuttings were placed on and covered with 6 mil plastic on- site. Soil cuttings and groundwater will be properly disposed of in a timely and appropriate manner after reviewing the analytical results and obtaining agency approval. MW2 and MW3 were moni.,ored in accordance with WaterWork 's QA/QC Plan. Su`:sequent to installation and well development, split water samples were collected from the monitoring wells MW2 and MW3 after purging a minimum of four well volumes (casing and sandpack) from each well . Stabilization of EC, pH, and tempera- ture was checked after purging and before and after sample col- lection to ensure samples collected were representative of forma- i4