|
SITE HISTORY
<br /> 1985 and 1986 Subsurface Investigations: Wells MW-1 through MW-12 were installed
<br /> during July 1985, and wells MW-13 through MW-22 were installed during April 1986.
<br /> Wells MW-1 through MW-19 were installed as part of Shell Oil Products US's (Shell's)
<br /> internal program to monitor groundwater near plant facilities. Wells MW-20, MW-21,
<br /> and MW-22 were installed to monitor groundwater down gradient of a separate-phase
<br /> hydrocarbon(SPH)plume identified at well MW-1.
<br /> 1987 SPH Recovery: During 1987, an SPH recovery program was initiated, and product
<br /> was recovered from wells MW-1, MW-15, and MW-17. Extracted fluids were
<br /> transported to Shell's Martinez refinery for recycling.
<br /> 1991 and 1992 Subsurface Investigations: Harding Lawson Associates (HLA) installed
<br /> well MW-23 during August 1991 and well MW-24 during December 1992.
<br /> 1993 Subsurface Investigation: Three phases of plume assessment were performed
<br /> during February and September 1993 (HLA, October 15, 1993). The scope of work
<br /> included completing 33 HydroPuncho borings (1,2,3,5, 6,9,10,14,16,18,20,25,26,28,
<br /> 30,31,32, 34,35,36,38 through 43,47,and 49 through 54),installing three shallow zone
<br /> groundwater monitoring wells (MW-25, MW-26, and MW-27), and installing one deep
<br /> zone well(DW-1).
<br /> 1993-2005 Groundwater Extraction (GWE) Operations: GWE began at the site in early
<br /> 1993. The pumping wells were MW-1,MW-23, and MW-24. The GWE system was shut
<br /> down after two months of operation due to limitations placed on the treatment of
<br /> wastewater at the Shell refinery.
<br /> A surface water discharge permit was obtained, and the GWE system was restarted
<br /> during November 1994. Two additional extraction wells, MW-11 and MW-16, were
<br /> added to the system. Treated groundwater was discharged to the Stockton Deep Water
<br /> Channel under a National Pollutant Discharge Elimination System (NPDES) permit.
<br /> During April 1995, well MW-17 was added to the GWE system. During the third
<br /> quarter 2000, well MW-13 was added to the GWE system. During April 2001, the
<br /> system was shut down due to more stringent NPDES permit requirements.
<br /> During October 2003, the GWE system was restarted and discharge to the sanitary
<br /> sewer began. The pumping wells were MW-10, MW-15, and MW-16. The system
<br /> operated intermittently until March 9, 2005 and has not discharged to the sanitary sewer
<br /> 241748(33) A-1 CONESTOGA-ROVERS&ASSOCIATES
<br />
|