ARCHIVED REPORTS XR0000240 - Laserfiche WebLink

Home Browse Search

PROBLEM ASSESSMENT REPORT AND CORRECTIVE ACTION PLAN 1.0 BACKGROUND 1_1 Site Description and History The project site consists of the Caltrans District 10 Stockton Yard maintenance facility located at 1604 South B Street in Stockton, California. The four acre site is part of Caltrans' District 10 Headquarters complex and is utilized as an equipment refueling, maintenance and storage facility. The approximate site location is depicted on the Vicinity Map, Figure 1. The project boundaries are shown on the Site Plan,Figure 2. The Stockton Yard maintenance facility was constructed in approximately 1955. Refueling facilities including gasoline and diesel underground storage tanks (USTs) were previously located within the northwest portion of the site. It is understood that one 5,000-gallon diesel UST one 10,000-gallon unleaded gasoline UST,two pump islands and associated product piping were removed from the site by Placer Tractor in December 1989. 1.2 Previous Environmental Studies The following documents were reviewed to aid in the preparation of this Problem Assessment Report and Corrective Action Plan(PAR/CAP): • Preliminary Site Investigation, Stockton Maintenance Station, prepared by Alton Geosciences dated July 9, 1992. • Site Investigation Report(s)for Stockton Yard, prepared by Geocon Environmental Consultants, Inc. (Geocon), dated June 29, 1995 and April 19, 1996. • Groundwater Monitoring Report - Fourth Quarter 1996, Stockton Yard Facility, prepared by Geocon,dated November 27, 1996. In March 1992, Alton Geosciences advanced two soil borings (SB-1 and S13-2)to a depth of 66.5 feet below the ground surface (bgs), constructed three monitoring wells (MW-1, MW-2 and MW-3) to a depth of 79.5 feet bgs,and collected soil and groundwater samples for chemical analyses. Site investigation work performed by Geocon between May 1995 and January 1996 was designed to provide additional information regarding the vertical and lateral extent of petroleum hydrocarbon impacts to soil and groundwater. Geocon performed one soil boring(SB-3)to a depth of 21.5 feet bgs, installed nine groundwater monitoring wells (MW-4 through MW-12) to depths between 75 and 81.5 feet bgs,constructed two vapor wells(VW-I and VW-2)to a depth of 75 feet bgs and collected soil and groundwater samples for chemical analyses. Project No.58100-06-11C -1- December 17, 1996