ARCHIVED REPORTS_XR0012192 - Laserfiche WebLink

Home Browse Search

3.0 FIELD INVESTIGATION Work at the site during this phase of investigation was performed in accordance with the MCA work plan dated July 5, 1994. San Joaquin Environmental Health Division approved the work plan in a letter dated July 18 , 1994 . 3. 1 Site-Specific Health and Safety Plan/Background I Review/Permitting MCA prepared a Site-Specific Health and Safety Plan (HSP) as required by the Occupational Health and Safety Administration (OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910. 120) . The HSP was prepared by MCA personnel following a review of site conditions with the project manager. The document was reviewed by all MCA pro]ect and field personnel and subcontractors performing work at the site. 3. 2 Soil Borings and Sampling Prior to the start of drilling a utility locator was employed to clear the boring locations. on September 12, 1994 a geologist from RESNA Industries (RESNA) of Escalon, California observed Spectrum Drilling of Stockton, California (a licensed California well driller) drill two soil borings (MW-7 and MW-8) using a truck- mounted drill rig equipped with 8-inch diameter hollow-stem augers. The locations of the borings are shown on the Figure 1. Soil borings MW-7 and MW-8 were drilled to depths of approximately 78 feet below ground surface (bgs) , which was approximately 13 feet below the first saturated zone encountered during drilling.. Both I recent and previous soil boring depths are summarized in Table 1. During the drilling of borings MW-7 and MW-8 soil samples were collected at five foot intervals, when changes in lithology were observed. The field geologist logged the materials encountered during drilling using the ASTM Standard Practice for Identification € of Soils (ASTM D-2488) . Logs of borings are presented in Appendix t A. Drill cuttings generated during drilling of the borings was stockpiled adjacent to the existing on-site soil stockpile and F covered with plastic sheeting pending characterization and disposal. MCA will submit a separate waste disposal plan for previously existing soil stockpiled on-site, and soil generated E during this investigation. 3. 3 Monitoring Well Construction Previous and current monitoring construction details are summarized in Table 1. On-site monitoring well MW-7 and off-site monitoring well MW-8 were constructed with schedule 40, flush-threaded, 2-inch diameter blank casing and well screen with 0. 020-inch slots. The well screen was installed at depths ranging from approximately 58 4 I J