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' above the sand, and hydrated to restrict entry of cement into the sand pack. The remaining annulus was backfilled with neat cement grout. A cast iron utility box with a steel apron was placed over the monitoring well and set in concrete at a level slightly above the surrounding grade. The well head was fitted with a locking expansion cap to help protect it from infiltration. Well construction details are illustrated on the well construction diagram in Appendix A. 3.5 Monitoring Well Development ' Prior to the emplacement of the bentonite seal, V&W developed the monitoring well by surging it with a vented surge block for about 10 minutes. After surging activities, the sand pack dropped about 9-inches. Following surging, the 9-inch drop in the sand pack was re-filled with ' more sand. ' 4.0 GROUNDWATER MONITORING 4.1 Groundwater Sampling Activities JJW commissioned Del-Tech to conduct groundwater monitoring and sampling activities on September 10 and 13, 1999. Prior to purging the five wells and collecting groundwater t samples, the depth to static groundwater was measured and recorded in the four of the five wells (excluding MW-2). The current groundwater gradient and flow directions are presented in Table I and Figure 3. Following water depth measurements, a 12-volt DC pump was used to ' purge the groundwater monitoring wells until at least two or more of the readings for temperature, pH, conductivity, and oxidation-reduction potential (ORP) approximately stabilized. Approximately 6 to 39 gallons were purged from each well, which corresponded to ' three well volumes. Following well purging and recharge, ground-water samples were collected with polyethylene, well-dedicated, disposal bailers and poured into precleaned 40 milliliter glass vials and one liter amber glass jars. Following collection, the water samples ' were immediately placed on ice in a cooler. Specific site conditions and sampling parameters can be found in the Well Sample Field Logs included in Appendix C. Del-Tech did not experience any ambient petroleum-like odors above the monitoring wells. ' The groundwater samples were transported under chain-of-custody to BSK Analytical Laboratories, a State of California certified analytical laboratory (Certification No. 1180). BSK analyzed the groundwater samples for the following parameters per the San Joaquin County ' directive: - Total petroleum hydrocarbons as gasoline (EPA method 8015 modified); - The aromatic volatile fuel components BTEX and MTBE (EPA method 8020); Additionally, groundwater samples MW-2 and MW-5 were also analyzed for the following biodegradation parameters: - Ammonia (method SM 4500-NH3-F); ' - Nitrate (method SM 4500-NO3-F); - o-Phosphate (method EPA 300.0); • - Heterotrophic Plate Count (method SM 9215). ' 3 JJW GEOSCIENCES Inc.