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. l Phase I Environmental Site Assessment City of Stockton Multi-Modal Station/Shopping Center Page 38 ` 1 Two USTs were removed from Valley Motors at 800 E Mani Street in 1990 Since the tank removals, groundwater quality has been monitored Laboratory analyses have indicated the presence of TPH-G, MTBE, and benzene Condor considers the site to be a de minimis condition as the site is approximately 500 feet and cross-gradient from the site • The sites at 601 and 647 E Miner Avenue both had USTs in the past and are currently being monitored Laboratory analyses of groundwater samples from 601 E Miner Avenue have indicated the presence of TPH-G, MTBE, and benzene Laboratory analyses of groundwater samples from 647 E Miner indicate the presence of MTBE at levels close to the California Public Health Services Maximum Contaminant Level of 143 Rg/L Condor considers these sites to be a de minimis condition as the sentinel monitoring well at 647 E Miner Avenue has only indicated the presence of MTBE The properties are also cross-gradient from the site 8.0 OPINION There are a number of issues concerning this area There are many sites that pose some degree of environmental risk, but these sites do not necessarily have enough known information to be considered recognized environmental conditions This area has many types of businesses, both presently and in the Z past, that use materials which if they were handled according to past standards that are no longer acceptable, which they are more likely to have been due to the long history with a lack of environmental regulations, this mishandling could present environmental Iegacies when they are discovered with future development Sites such as auto repairs shops may have used petroleum products such as gasoline, diesel, motor oil, crank case oil, gear oil, gear lube, and grease They also may have used solvents and parts washers Businesses like auto body shops many times use paints and solvents How these solvents were disposed of in the area in the past is unclear As well, there are the underground storage tanks in the area Some tanks are better documented than others, but these tanks may also provide sources of large volumes of potential contaminants Therefore, the area is at some degree of risk for widespread contamination if these materials were not handled according to now acceptable practices came into contact with groundwater and have been mobilized and transported 4 9.0 CONCLUSIONS While the area that this Phase I ESA was conducted in did include a large number of former residential units, there was still enough mixed commercial and light industrial use to warrant concern Of special concern are businesses like auto repair shops, auto body shops, and service stations, with underground storage tanks, that may have had large quantities of hazardous materials or waste that could be potential sources Our approach in evaluating this area is to start with the largest environmental concerns and to work towards the smallest On the large end of the scale would be potential source of contaminants that, si if released and discovered, could achieve the status of a site with extensive groundwater contamination in an area large enough to affect several parcels We believe the chances of a site of this magnitude are unlikely Next on the scale would be those sites that can contribute to large scale and costly groundwater remediation issues This area has some risk of that and there are potentially three to ten properties that could have had large enough source and composition of materials to have produced widespread negative impacts to groundwater On the small end of the scale would be the historical handling of common auto- maintenance materials like motor oil removed from vehicles and disposed of in the back of even a residential yard Taken on a whole, it is difficult to believe this area doesn't have some degree of environmental concerns The question for the client is to what degree they choose to pursue further 0 investigation to ascertain the potential environmental impacts and resulting costs of any cleanups t� CONDOR