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SITE-SPECIFIC HEALTH AND SAFETY PLAN FOR PHASE II ENVIRONMENTAL SITE ASSESSMENT Site Background and Chemical Hazards July 7, 2023 ,i7E BACKGROUND AND CHEMICAL HAZARDS The Site is located at the southeast corner of West Lane and Alpine Avenue in Stockton, California. The site is further located in Township 2 North, Range 6 East, Section 30 Mount Diablo Base and Meridian (Stockton West Quadrangle, 7.5-Minute USGS Topographic Series, 1968, photo revised 1987), in a topographically flat area at an elevation between 5 and 10 feet above mean sea level. The San Joaquin County Tax Assessor's Office lists the site's boundaries as Parcel 17 on Map 080 in Book 117 (APN 117- 080-17). (AGE, 2009) This site is currently an abandoned Pacific Pride commercial fueling station which had an open case with the San Joaquin Environmental Health Department(Case# 1288);the case was closed on January 5, 2010 Prior to 1985, the site was utilized as a retail fueling station. In approximately 1995, the site was converted to a commercial card-lock fueling station (Pacific Pride) until approximately 1998. While operating as a commercial card-lock fueling station, Pacific Pride utilized two 10,000-gallon gasoline and one 10,000- gallon diesel USTs (Figure 2). The USTs were removed from the site in February 1999. AGE has no knowledge of property usage prior to 1985. Two UST Unauthorized Release (Leak)/Contamination Site Reports (UAR) were filed by San Joaquin County Environmental Health Department(EHD)on 01 March 1989 and 17 May 1999; as a result,the EHD directed that a subsurface investigation be performed beneath the UST area. Two 10,000-gallon gasoline and one 10,000-gallon diesel USTs were removed from the site on 24 February 1999. Soil samples were collected from beneath the tank pit and product piping and were submitted to a California Department of Public Health (CDPH)-certified laboratory for analysis of petroleum hydrocarbon constituents. Total petroleum hydrocarbons quantified as gasoline, diesel and motor oil (TPH-g,TPH-d and TPH-mo, respectively)were not detected in soil samples collected beneath the former USTs; however TPH- d and TPH-mo was detected beneath the product piping samples at concentrations as high as 15 milligrams per kilogram (mg/kg) and 92 mg/kg, respectively. Benzene, toluene, ethylbenzene and xylenes (BTEX compounds) were detected in samples collected beneath the USTs and product piping at concentrations ranging as high as 7.3 mg/kg xylenes. Methyl tertiary butyl ether(MTBE)was detected in samples collected from stockpiled soil, piping and the UST pit at concentrations as high as 3.5 mg/kg. Total lead was detected in samples collected beneath product piping at concentrations ranging as high as 40 mg/kg. Subsequently, the EHD required an assessment of the lateral and vertical extent of the hydrocarbon impact. Based on the analytical results of soil samples collected during the above February 1999 UST removal event, a preliminary site investigation was required by the EHD by letter dated 03 June 1999. The following is a brief summary of the site assessment investigations conducted at the site to date: • 31 August 1999 - Six soil borings (P-1 through P-6)were advanced at the site to depths of 35 feet bsg (Figure 2). Laboratory analysis of soil samples detected TPH-g from borings P-1, P-3 and P-4 at concentrations as high as 60 mg/kg; TPH-d was detected in the same borings at concentrations as high as 110 mg/kg. BTEX compounds were detected in soil samples collected from P-3 and P-4 at concentrations as high as 4.4 mg/kg; MTBE was detected in soil samples collected from P-1, P- 3, P-4 and P-5 at concentrations as high as 39 mg/kg. Analytical results of soil samples are summarized in Tables 1 and 2. Field procedures and sample results were outlined in Preliminary Investigation and Evaluation Report, dated 11 November 1999. • 05 and 06 June 2000 - One soil boring (P-7)was advanced to 65 feet bsg and three ground water monitoring wells (MW-1, MW-2 and MW-3)were installed at the site to depths of 60 feet bsg (Figure 2). A total of seventeen soil samples were collected from MW-1, MW-2, MW-3, P-7 and submitted for laboratory analysis of TPH-g, TPH-d, BTEX, MTBE, ethyl tertiary butyl ether (ETBE), tertiary Stantec 3.2