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Mr. Ron Rowe September 4, 1997 Page 4 3.2 Monitoring Well Installation The boreholes will be converted to a groundwater monitoring well upon reaching the desired well completion depth (Table 1). Wells will be completed with 10 to 30 feet of capped, flush-threaded, 2-inch diameter Schedule 40 PVC 0.020-inch machine-slotted well screen from the base of the borehole and completed with blank casing to ground surface. For each well location, filter sand will be placed in the annular space between the wall of the borehole and casing,to a height of two to three feet above the screened interval. Two feet of bentonite pellets will be placed above the sand and hydrated. A cement grout mixture(5%bentonite) will then be place into the remaining annular space to ground surface. A flush-mounted,protective watertight monument cover will then be grouted slightly above ground surface to complete the well installation. The well will also be fitted with a locking watertight well cap. 3.3 Monitoring Well Development,Sampling and Surveying The cement grout surface seals will be allowed to set for a minimum of 48 hours prior to monitoring well development. Prior to well development,SECOR will measure depth-to-groundwater for the new and existing monitoring wells, including Texaco monitoring wells MW-6, MW-8 and MW-14. The new wells will be developed by alternately bailing and surging until the groundwater is reasonably free of sediment and at least 10 well casing volumes are removed. Monitoring well MW-1 will also be purged of at least three well casing volume by bailing. During well development and purging, measurements and observations of pH,electrical conductivity,temperature,color, and turbidity will be recorded. Following well development and purging,SECOR will collect groundwater samples from monitoring wells MW-1,MW-2,MW-3,MW-4,MW-5,MW-6,MW-7,and VE-1 for chemical analysis. SECOR will attempt to coordinate sampling with the Texaco Service Station and other responsible parties for the next quarterly monitoring event in an effort to gather time correlative groundwater elevation and chemical data. Prior to sampling,wells will be allowed to recover to 80%of the initial water level prior to development. Groundwater samples will be collected using a disposable PVC bailer and decanted directly into laboratory-supplied sample containers. Each of the sample containers will be labeled, sealed in plastic bags, and placed in an ice-filled cooler. The samples will be submitted to a California state-certified analytical laboratory along with a completed chain-of-custody record. The newly-installed groundwater monitoring wells and existing wells MW-1 and VE-1 will be surveyed for top of casing elevation relative to mean sea level (msl)by a professional land surveyor and tied into the City of Stockton Benchmark No. 186. 3.4 Quarterly Groundwater Monitoring Following this phase of additional Site investigation,SECOR will initiate quarterly groundwater monitoring and reporting activities for the seven Site monitoring wells. Groundwater monitoring activities will be coordinated with the SJCEHD so that collected groundwater elevation and chemical data can be obtained on the same day as the data collected from the surrounding properties with petroleum hydrocarbon-impacted groundwater. Groundwater monitoring activities will include well sounding,purging and sample collection, HASFFB\STOCKTON\S FFB W KP.RPT