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CLOSURE REQUEST 5-31-94 the 30 to 60 foot depths . Two more ground water monitoring wells were installed on August 8 and 9, 1990 (MW5 and MW6) . MWS is a 4 inch, F480 Sch 40 PVC with 0 . 02 inch machine slot from the 30 (28 feet true vertical) to the 65 (61 feet true vertical) foot depths, was installed into a 10 inch hollow stem augered boring that was slant drilled beneath the store at approximately 21 degrees off of vertical . MW6 is a two inch F480 Sch 40 PVC well, with 0 . 02 inch machine slot from the 30 foot to the 60 foot depths installed into a 8 inch hollow stem augered boring The last ground water monitoring well installed for this site, was the off-site well MW7 . MW7, installed on July 21, 1992, is a four inch, F480 Sch 40 PVC with 0 . 01 inch machine slot from the 50 foot to the 70 foot depths and was installed into a ten inch hollow stem augered boring. The selection of well sites was based on the earlier sample results from the tank excavation and review of local and regional ground water gradient maps . Historic ground water elevations as measured from the monitoring wells show that the screened intervals for all wells was properly selected, see Appendix F for boring/construction logs and Tables 1 and 2 for ground water measurements Monitor Well Development and Sampling • Well development for MW1, MW2 , MW3 and MW4 occurred on December 11, 1989, three days after completion of MW4 . Monitor wells MW5 and MW6 were developed on August 15, 1990 and Monitor well MW7 was developed on July 24 , 1992 Prior to development depth to ground water measurements were obtained form a reference point notched into the top of the casing (all wells were surveyed by a California Licensed Surveyor on October 1, 1992, prior to that time a WEGE geologist surveyed the well casing evevations with a transit and rod and projected a contour elevation from the USGS topographic map, Figure 2 , to well MW4 as a datum) Once the depth to water measurements were obtained from all of the wells, a two inch swabber or four inch swabber was used to agitate the sand pack adjacent to the screened section of the well exposed to the ground water. Each well was swabbed for approximately 15 minutes . After the wells were swabbed the well was purged until depletion or until the well water came clear, using a pneumatic down hole pump, except for MW7, a vacuum lift pump was utilized. Sampling of the initial wells (MW1 - MW4) occurred on January 4 , 1990 . Prior to sampling the monitor wells, depth to ground water is measured by lowering a water interface probe into the well . Then the well is purged, to remove stagnated water, until the pH, conductivity, and temperature stabilizes, ie . approximately five to 15 gallons per well . A sterile disposable bailer is then lowered into the well to collect the ground water sample . The water is then slowly poured into EPA protocol cleaned glass containers (1 liter Boston round and four 40ml VOA vials) , capped, . labeled, and placed in an ice chest on ice and cooled to 40C. The samples are then chain of custody hand delivered to a Department pagel0