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Q Limited Phase 11 Subsurface Investigation Report 902-908 East Scotts Avenue Stockton,California a ntea g ro u p Antea Group Project No. UPR82572A Groundwater,to address worker safety during potential construction activities on the site. 3.3.1 Volatile Organic Compounds (VOCs) The laboratory tested a total of 16 soil samples for VOCs. Only two of the samples submitted (1.0-1.5 feet bgs in borings B3 and 137) had detections of VOCs greater than the laboratory reporting limits(LRLs). All of the detections were well below their respective RSLs and SSLs. At both locations where VOCs were reported, Antea Group submitted a deeper sample (4.5-5.0 feet bgs) for VOC analyses, and no concentrations above the laboratory reporting limits(LRLs)were detected. The reported VOC compounds coincide with the higher PID readings noted during this investigation, and they appear to be closely related to the petroleum constituents that were also reported in both borings (see Section 3.3.4, below). Table 1 includes a summary all VOCs testing results. 3.3.2 Polynuclear Aromatic Hydrocarbons (PAHs) Antea Group submitted a total of 16 soil samples for PAH analysis. One or more PAH compounds were reported in over half the soil samples analyzed at locations scattered across the site. PAH detections at concentrations greater than the LRLs were reported only in samples collected from depths of 1.0 to 2.5 feet bgs. The sample collected from 1.0-1.5 feet bgs in B10 was the only sample with industrial RSL exceedances for five constituents (benzo(a)- anthracene, benzo(a)-pyrene, benzo(b)-fluoranthene, dibenz(a,h)-anthracene, and Indeno(1,2,3-cd)-pyrene). The concentration of benzo(a)-pyrene (1.500 milligrams per kilogram (mg/kg)) was the only constituent equal to the Direct Exposure SSL and greater than the RSL. Table 2 includes a summary of the PAH analytical data. The highest overall PAH detections at B10 coincide with other contaminants reported in B10 (hydrocarbons) and may be indicative of a release in that area and not of a site-wide condition. Overall,the minor impacts of PAHs appear to be scattered at varying low concentrations across the site, indicative of a possible background condition of the shallow fill beneath the site. This is not uncommon at properties such as this,which has been occupied industrially dating back to the 1800 and over a large time span where coal was used for fuels. 3.3.3 Total Metals Antea Group requested metals analyses for the list of 17 California metals (commonly referred to as "Title 22" metals) in 18 soil samples. The analytical data reported detections of 15 metals (antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, thallium, vanadium, and zinc) in soil samples collected as part of this investigation. The laboratory reported three metals (arsenic, chromium, and vanadium)at concentrations exceeding EPA's Region 9 RSLs for an industrial setting. Arsenic and barium were the only two metals detected above the Direct Exposure SSLs. Table 3 includes a summary of the total metal analytical data and provides a comparison of detections to SSLs, RSLs,and background reference concentrations. 7 www.anteagroup.com