ARCHIVED REPORTS_XR0006733 - Laserfiche WebLink

Home Browse Search

I Canepa`s Car Wash 6230 Pacific Avenue, Stockton, California April 28, 1994 Phase 17 Site Characterization Page: 7 the alluvial flood and delta plains of the mayor rivers and tributaries of the region The region persisted as a lowland or shallow marine embayment during the entire Cenozoic period The surface of the Valley is composed of unconsolidated Quaternary sediments The hthologic units encountered in these borings were interbedded inorganic micaceous clayey silts and silty clays with numerous sands and silty, clayey sands of varying thicknesses This is typical of the valley fill deposits in the region 7.0 Hydrology California and Federal Governments have mandated that virtually all groundwater is beneficial for current or future use unless it can be demonstrated that no beneficial use is known This aquifer is considered to be of beneficial use and as a result, must be protected from contamination Those identified uses include agriculture and industrial, as well as potential use for animal or human consumption ■� &0 Conclusions and Recommendations A soil contamination plume exists down to the groundwater table under the former fuel dispensing islands, which is in the same area as the present fuel island canopy The projected limit of soil contamination is shown as contours of depth below ground level to the top of the plume (Figure 10) There is a network of nine soil vapor extraction wells installed under the dispenser island, and a combustion system designed to treat the soil contamination problem has been installed and is awaiting the final operating permit ;-.A- Groundwater has been impacted m monitoring wells MW-1, 2, 5, 7, & 8 (Figure 10) Wells MW-3, 4, & 5 are ND (None Detected), and NfW-8 is new the limits of groundwater ' contamination The plume is defined to the northeast, east and near to the southeast limits Definition is not complete to the west and southwest, as monitoring wells would have to be installed under Pacific Avenue(a major 4-lane thoroughfare)and a restaurant The groundwater gradient mound anomoly (Figure 11, 3130194) can only be caused by revharge into the ground,vater 'rhe previo,.:s grnrl,Pnt maps of 1111, 1217 and 12/29/93 did not have sufficient data to reveal the whole mound There are three probable sources of recharge 1 )the car wash recycles wash water through a pit system under the building, 2) a lealang or broken sewer line that crosses the area, and 3 )a leaking water supply line, although this should have become evident at the surface by now