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V Mr, R.W. Conlon 202J1 50-4150 October 9, 1990 Page 10 augers. Monitoring wells were constructed with 4-inch diameter, 0.020-inch machine slotted PVC well screen,which was placed within the waler-bearing zone. Four-inch diameter b!ank PVC casing extends from the well screen to the surface in each well. A well pack consisting of appropriate grain-size sand, was placed in the annulus between the borehole and the casing to approximately 2 feet above the screened intervals in each well. The wells were completed with a one foot bentonite seat above the sand pack,and a sand/cement slurry which extends to the surface. Traffic-rated street boxes and locking caps were installed for access to each well, Well construction details are presented an the drill logs in Appendix 11, 3.6 PETROLEUM RECOVERY MWA was first gauged on June 26, 1989 and 4,78 feet of separate-phase petroleum was observed floating on the water lat;e. To stcre the petroleum recovered from the water table,a temporary compound was built to house a 650-gal;on containment tank. The appropriate permits were obtained from the Iccal fire department to temporarily store petroleum in the compound. Beginning July 25, 1989, petroleum was recovered by hand bailing methods and then transferred to the storage tank three times a week. As petroleum thickness decreased,the interval between bailing dates increased. In the months of November and December the petroleum thickness had decreased to 0.30 and 0.40 foot,respectively. On February 8, 1090,the storage tank was vacuumed out by licensed waste haulers and the tank was removed from the site. Approximately 45 gallons of petroleum had been recovered between May 1989 and February 199.1. Table I presents the gauging data of the petroleum thickness in MW-1. 3.7 SURVEYING The site was surveyed to locate the monitoring wells and determine their elevations. Elevations of the tops of the PVC well casings and street boxes were surveyed to the nearest 0.01-fool. Elevations were corrected to mean sea level datum as indicated by the United States Geological Survey. The bench mark used in the survey is the City of Stockton bench mark number SS-22 located on the north side of West Charter Way at the approximate center line of French Camp Turnpike Road. The resulting site plan is shown an Figure 6. Well elevations are presented in Table 2. GROUNMATIER TwINOLOGY,INC.