ARCHIVED REPORTS_REMEDIAL INVESTIGATION REPORT 2000

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3.0 INVESTIGATION PROCEDURE 3. 1 Soil Borings From November 2 through 6, 1989 , 18 soil borings were drilled for the purpose of determining sub-surface conditions. Sixteen of the borings were advanced to six feet below grade. Two borings were advanced to 40 feet to install ground water monitoring wells. The borings and well locations are shown on Figure 2. The two monitoring wells were located near the former diesel storage area and paint storage area. The shallow borings are spaced to cover the remainder of the site. Drilling was conducted by Osterberg and Stewart (CA license #C57-446670) using an Ingersol/TH-10 rig with 8 and 10-inch (O.D. ) hollow stem augers. The drilling was performed under the direction of a field geologist who maintained a continuous log of the materials encountered using the Unified Soil Classification System (Appendix I ) . Soils were sampled at 5.5 feet below grade in the 16 soil borings and at 5 foot intervals in the 2 monitoring wells. The samples were collected in 2-inch diameter by 6-inch long brass tubes using a California Modified Sampler. The samples were collected, preserved and transported under chain-of-custody requirements in accordance with standard EPA Protocol. The samples were delivered within 48 hours of collection to Sequoia Analytical Laboratory, a State certified hazardous waste laboratory. The laboratory composited the samples from borings 1-7, 8-14 and 15-16 into three samples for the analysis. The sample collected at the water table interface from each deep boring were submitted for analysis. The five samples were analyzed for priority pollutant metals and volatile organics by EPA Method 8240. 3.2 Monitoring Wells The two deep soil borings (MW1 & MW2) were completed as 2- inch diameter monitoring wells. Specific details of the well completion/construction are included on the boring log S (Appendix I ) . After completion, the depth to groundwater in the monitoring wells was measured using a conductivity probe. The two monitoring wells were developed by pumping at a rate of 1.4 gallons per minute (gpm) for a period of 45 minutes in order to remove at least four well volumes (casing plus sandpack ) . Groundwater samples were collected using a teflon bailer with a bottom emptying device. The samples were contained, preserved and transported to Sequoia Analytical Laboratories, a state certified hazardous waste laboratory, in accordance with EPA protocol. The samples were analyzed for priority pollutant metals and volatile organics by EPA Method 8240. 2