WORK PLANS - Laserfiche WebLink

Home Browse Search

FLUOR DANIEL GTI TASK 3: WELL CONSTRUCTIONIDEVELOPMENTISAMPLING Groundwater extraction wells will be constructed of 6-inch Schedule 40 poly-vinyl-chloride (PVC) casing with flush threads and 0.020-inch-slot well screen. Well screen will be installed from approximately 4 to 15 feet BGS. -foot length of blank ca sin will be installed below the bottom of the screened interval from 15 to 20 feet BGS. The annular space will be filled with bentonite from 20 to 16 feet BGS, and sand from 16 feet BGS to 1 foot above the top of the well screen. The well will�r sealed with 2 feet of bentonite, followed by a neat-cement grout to grade containing a mixture of 95 pounds of Portland Type Illi cement to 5 gallons of clean water.The extraction well will be protected by a traffic rated, 17 inch by 30 inch by 24 inch deep vault. Following installation,the recovery wells will be developed by using a surge block and bailing to remove fine-grained sediments from the well and filter pack. Water from the development process will be placed in DOT-approved 55-gallon drums pending treatment through the existing groundwater remediation system . At least 48 hours after development,the groundwater extraction well will be gauged to measure static liquid levels. Liquid levels will be monitored using an ORS Environmental Equipment INTERFACE PROBEm Well Monitoring System,which consists of a dual optical sensor and electrical conductivity probe that distinguishes between water and petroleum products. The top of casing of the two wells will be professionally surveyed relative to existing wells at a later date. TASK 4: TRENCHING AND GROUNDWATER EXTRACTION Two trenches for the groundwater extraction system piping will be excavated to connect the newly installed groundwater extraction wells with the existing GWES piping (Figure 2). A 2-inch diameter PVC line for GWE and two 1-inch diameter PVC lines for power and pump controls will installed in the new trenches and run into the five extraction well vaults. A down hole electrical submersible pump will be installed in the tank pit well to extract groundwater and determine recovery rates. The pump will be operated at maximum sustainable rates to monitor influence in wells MW-8, MW-9, and MW-10. TASK 5: INSTALLATION OF FUTURE EXTRACTION LINES In addition to pump control and GWE lines, one soil vapor extraction line for future use will be installed in the trenches, run into the five extraction vaults and capped. A horizontal PVC screen will be installed into the two trenches to allow for future recovery of soil vapor. C23142.wkp{Sthl-51} -. - _ .-- -•- -----_-- --- Addendum to Work Plan for Groundwater Extraction Well Installation July 5,1996 The Southland Corporation,455 Grant Line Road,Tracy,CA 3