ARCHIVED REPORTS_XR0010741 - Laserfiche WebLink

Home Browse Search

• Closure Report 3 The Southland Corporation,9110 Thomton Road, Stockton,CA December 5, 1995 ■ Depth to groundwater at the site has fluctuated historically from approximately 30 to 50 feet BGS Historical and current groundwater flow at the site is towards the east or southeast Potenbometric surface maps for February 23, 1987,July 26, 1988, June 1, 1990,April 2, 1993, and September 6, 1995 are provided as Figures 4 through 8 Fluctuations in groundwater elevation are illustrated on Figure 9 ■ In January and February 1993, nine confirmation soil borings (A-G, I,J) were advanced to depths of 45 feet below ground surface (BGS) In August 1995, seven additional soil confirmation borings (K- Q)were advanced Results of soil confirmation bonngs are discussed in Section 4 2 of this report Boring logs are provided in Attachment 4 12 Remediation Pilot Tests 1.21 Groundwater Extraction In March 1988, a 24-hour aquifer pumping test was performed to acquire data with which aquifer parameters were estimated for the groundwater remediation wells A constant rate pump test at an extraction rate of 5 gpm from RW-1 resulted in a calculated Transmissivity (T)value of 5200 gpd/ft Capture distances were calculated using the following expressions • r= (229'0)1(T'I) r,= r'1 6 with r= Downgradient distance to stagnation point(ft) rc= Crossgradient distance to stagnation point(ft) Q = Extraction Rate (gpm) T= Transmissivity (gpmtft) I = Stabc groundwater gradient Using an extraction rate of 5 gpm, a T of 5200 gpd/ft, and a gradient of 0 002,downgradient and crossgradient groundwater capture distances of 110 and 180 feet were calculated The calculated capture zone at 5 gpm is illustrated on Figure 10 122 Soil Vapor Extraction On January 13, 1994, a soil vapor extraction (SVE) test was conducted to determine if hydrocarbons were present in subsurface soils,to estimate radius of capture of vapor extraction, and to estimate potential hydrocarbon mass extraction rates Tests were conducted on mondonng wells MW-1 through MW-5, MW-8, MW-10, MW-12, primping wells PW-2 and PW-3, and vadose wells VP-1,VP-2 and VP-3 (Figure 2) cb,,,,e2 rvasn+L-45 5) OFIC GROUNI)ll-XI l,lt TI;CHNOLOG)