SITE INFORMATION AND CORRESPONDENCE 1995-2004

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• 0 8.3 Characterization of Site and Potential Receptors 8.3.1 Summary of Physical Description of Area The Stockton MGP site is known as the PG&E Stockton gas load center and service yard located at 535 Center Street, in a commercial, industrial, downtown area of Stockton, California (Figure 2-4). The layout and surrobnding land uses are described in Section 2.1 of this report. Selected information is repeated below for the consideration of this environmental assessment. The Stockton former MGP site is identified as Areas I, II, and III (Figure 8-1). PG&E currently owns Areas I and II. Morton Paint Company currently owns Area III. Area I is used as a gas load center and service yard; it is completely paved with asphalt. Area II currently houses Station A Electrical Substation and the communications facility; the entire area is covered with compacted gravel with the exception of a paved driveway and parking lot. The parcel referred to as Area III is currently used as a paint manufacturing facility. The entire area is paved with asphalt and contains three buildings. The absence of suitable habitat in all three areas limits plant and animal diversity. The nearest surface water is south and west of the site. The Stockton Deep Water Channel, a man-made and dredged extension of the San Joaquin River, is located ap- proximately 2,500 feet northwest of the site (Figure 8-1). Mormon Slough is located 300 feet south of the site and drains into the Stockton Deep Water Channel. Lower Mormon Slough is tidally influenced from the Stockton Deep Water Channel up to Commerce Street where it had an elevation of 0.29 feet msl. Lower Mormon Slough is connected to upper Mormon Slough by an underground 8-inch corrugated pipe that lies transverse to Commerce Street. Upper Mormon Slough, the nontidally influenced portion of the slough east of Commerce Street, had measured elevations of -0.19 to 4.9 feet msl. Because water does not normally reach the level of the 8-inch pipe, the amount of moisture in upper Mormon Slough is dependent on surface water runoff. Surface water runoff from the site (with the exception of the transformer storage yard in Area II) generally enters the City's storm drain system and eventually discharges into the slough. In Area I, the southern half of the yard is drained by sheet runoff to the south. Surface water runoff from Area I enters one of two storm drain systems. The northern half of the site drains to storm sewers on the corners of Commerce and Church Streets and Church and Center Streets. A storm drain on the eastern side of the site that drains approximately the middle 20 percent of Area I is a part of this system (PG&E, 1990) (Figure 4-1). These storm drains eventually discharge into lower Mormon Slough, west of the site (Figure 4-1). Runoff from the southern portion of the site drains to a storm sewer inlet on Hazelton Avenue at the Center Street overpass, and discharges to upper Mormon Slough. Surface water runoff from Area II flows through a collection system and is collected in a sump with a capacity of approximately 1,932 cubic feet (Figure 4-1). The sump is 10010427.SFO 8-2