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Subsurface Investigation Report Installation of Wells MWS,MW6, and MW7 640 N El Dorado Street, Stockton, CA I 2.0 PROCEDURES FOR ADDITIONAL INVESTIGATION 21 Permitting and Protocols I Prior to initiating fieldwork, well installation permits were obtained from E14D All fieldwork was performed in accordance with Ground Zero's Site Safety Plan and Quality Assurance/Quality Control Plan ' 2.2 Drilling, Soil and Groundwater Sampling Between May 6 and May 23, 2003, Ground Zero personnel supervised the drilling and sampling of three ' soil borings and the installation of three groundwater monitoring wells Fisch Environmental (C57- 683865) conducted the drilling and well installation Three continuous-core pilot borings (SB9, SB10 and SBI I) were advanced using a "direct-push" drilling rig for lithologic logging and subjective ' evaluation of soil and groundwater contamination Three groundwater monitoring wells (MWS, MW6 and MW7) were subsequently installed at the same locations as the pilot borings All fieldwork conducted at the site was performed under the supervision of field geologist Sean Garvey and project ' manager John Lane, a California Registered Geologist Ms Lori Duncan of EHD conducted grout inspections and observed field activities Figure 3 shows the locations of the pilot borings and monitoring wells Borings SB9, SB 10, and SB 11 were advanced to approximately 50 feet below surface grade (bsg) Where possible, soil samples were collected continuously using a 4-foot long core sampler lined with ' new 2 inch diameter polyethylene sleeves A phototonization detector (PID) was used to monitor the presence of VOCs in the soil Discrete groundwater samples were also collected from each boring by driving a groundwater sampling device to the desired depth, then retracting the probe rods to expose the ' screen to the formation A 0 17-inch diameter PTFE tube equipped with a stainless steel check valve was then inserted into the rods to the bottom of the of the sampler Water was extracted from the boring by creating a positive displacement effect within the tubing, forcing the water sample to the surface where it ' was collected directly into the appropriate sample containers Soil_and-groundwater samples selected_for laboratory analyses,_based on field observations and field screening results, were sealed, labeled, and immediately placed in an ice chest cooled to a temperature of ' approximately 4° Centigrade The-samples were submitted under chain of custody protocol to Argon Laboratory(FLAP 2359)or possible analysis ' Each completed direct push boring was backfilled to the ground surface with neat cement grout All drilling and sampling equipment was decontaminated prior to use and between sample collection by washing with a laboratory grade detergent and rinsing with water to minimize the possibility of cross ' contamination Waste soil and water generated during drilling and well installation activities were placed into properly labeled DOT approved storage containers, and were subsequently transported off-site for disposal at licensed facilities The soil was transported to Forward Landfill in Manteca and the water t was transported to the Riverbank Oil Transfer Station Copies of the non-hazardous waste manifests are included in Appendix 1 1 -2- 1