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Groundwater Monitoring <br /> Well Installation and <br /> ARCADIS Sampling Work Plan <br /> PG&E McDonald Island <br /> Compressor Station <br /> 2. Background <br /> The following sections provide a description of the site and a summary of previous site <br /> investigations. <br /> 2.1 Site Description <br /> The site is located on a man-made island in the Sacramento-San Joaquin Delta. The <br /> nearest main surface water body to the site is the Whiskey Slough,which is located <br /> approximately 0.75 miles southeast of the site.The site was formerly a natural gas <br /> production field and has been used by PG&E since the 1960s as a below ground, <br /> natural gas storage facility.An aerial photograph of the site is presented in Figure 2. <br /> Equipment on the island includes gas compressors that push natural gas into ground <br /> storage, gas wells that retrieve natural gas, and processing equipment that returns the <br /> gas to consumer quality.This equipment includes gas dehydrators and odorizers and <br /> assorted equipment needed to transmit the gas into the transmission and distribution <br /> system. <br /> 2.2 Previous Site Investigations <br /> 2009—Site Renovations and Initial Discovery <br /> PG&E discovered apparent petroleum-impacted soil during renovation activities at the <br /> site in December 2009.Approximately 90 cubic yards of soil were excavated from the <br /> C-51 aboveground tank site area. Soil samples were collected from the excavation <br /> area and were found to contain concentrations of total petroleum hydrocarbons(TPH) <br /> as gasoline(TPH-g)and diesel(TPH-d), benzene, ethylbenzene and xylenes. These <br /> impacts were thought to be related to the lube oil storage tank or gas condensate <br /> storage tank that were formerly located in that area of the site.The excavation was <br /> stopped pending additional soil characterization to delineate the area of impacts. The <br /> excavation boundaries are shown on Figure 3. <br /> 2010—Soil Boring Installation <br /> In April 2010,ARCADIS conducted additional soil sampling activities in accordance <br /> with the Site Sampling and Soil Removal Work Plan(ARCADIS 2010a).A total of 18 <br /> soil borings(SB-01 through SB-18)were advanced in the vicinity of the excavation. <br /> Soil samples were collected and analyzed for TPH-g,TPH-d, TPH as motor oil(TPH- <br /> m), and benzene, toluene, ethylbenzene and xylenes(BTEX). Soil results were <br /> Mcdonald Island Addtl MW Installation Work Plan.Do 2 <br />