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Soil Sampling Workplan Former Manufactured Gas Plant—Lodi,California oil tanks of which one was connected to a four-inch oil supply line in the northeast quadrant of the Site (Figure 3). Historical documents indicate the four-inch oil supply line trended east-west and was used to convey crude oil brought to the Site by rail to the oil storage tanks. In 1926 PG&E acquired ownership of the Site including Parcels A and B and continued operation of the MGP until 1928 when natural gas became available to the City of Lodi. Subsequently, the MGP ceased operation in 1928. The generator and boiler building were demolished in 1931 and the three gas storage holders were removed in 1934 and 1956. In 1958 PG&E sold Parcel A (the 25- foot wide section in South Sacramento Street located adjacent to the Site's west property limit) to the City of Lodi for street widening and Parcel B to the Central California Traction Company (CCTC). Beginning in 1958, Parcel A was used by the City of Lodi for street improvements and widening and Parcel B was used primarily for storage by CCTC. Circa 1970 Parcel B was used for warehousing by the California Fruit Exchange. In 1988 Parcel B (Site) was sold to the Reynolds Packing Company, and in 1992 the Site was reacquired by CCTC. In 2006, PG&E reacquired ownership of the Site (Parcel B) from CCTC for the purpose of investigation and remediation. The City of Lodi remains the owner of Parcel A. In 2008, the general shop and store room building (meter house) was demolished. In 2009,the two former water supply wells were abandoned in-place under permit with the San Joaquin County Environmental Health Department. 2.3 SITE GEOLOGY The City of Lodi is underlain by alluvial soils of the Modesto Formation (Quaternary) deposited by runoff from surrounding mountain ranges. The alluvial layers are part of the major aquifer system that runs the length of the valley. The aquifer is recharged by the Mokelumne River which borders the City of Lodi to the north. Subsurface investigations conducted to date have identified soils at the Site to consist primarily of dark yellow to dark brown fine-grained sand and silty sand, which grades to sandy silt and clay at various depths and locations. Significant deposits of sandy clay (greater than 5 feet thick) were encountered at borings SB-9, SB-10, SB-15, and SB-16 located in the central portion and southeast quadrant of the Site, and within the footprint of former gas holder #3 situated in the southwest quadrant of the Site. Within the footprint of the former oil tank (boring SB-6) fill material consisting of sandy gravel with petroleum hydrocarbon staining and debris was encountered to 12.5 feet bgs,and was observed to be underlain by wood at approximately 13 feet bgs. A geophysical investigation conducted during the RI (Stantec, 2010a) identified the following subsurface features at the Site: concrete foundation of former gas holder#3 in the southeast corner of the Site; debris within the footprint of the former oil tank in the central section of the Site; an east-west trending four-inch diameter cast iron inactive pipeline located one feet bgs between the former oil tank and the Site's eastern property limit; concrete footings suspected to be associated with the former generator and boiler building in the central section of the Site; several unidentified utility conduits in the northwest corner of the Site within the footprint of the former general shop and storeroom building (meter house); two ten-inch diameter steel inactive historical gas distribution lines located two feet bgs that extend 12-feet into South Sacramento Street from the former general shop and storeroom building (meter house); several linear features suspected to be utility conduits TERRA PACIFIC GROUP Page 7 October 19, 2012