ARCHIVED REPORTS XR0005965 - Laserfiche WebLink

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. 1.0)INTRODUCTION Upgradient Environmental Consultants (Upgradient) is under contract to William Peters to perform site assessment and quarterly monitoring of groundwater contamination at the Kwikee Foods Mart on Country Club Boulevard in Stockton, California. The site is included in the Local Oversight Program of San Joaquin County Department of Health Services, Environmental Health Division (PHS/EHD), under the supervision of Michael Infurna, REHS. In early April, 1998, Mr. Infuma approved an amended work plan to assess the extent of soil contamination at the site. This assessment was performed in May, 1998, and the purpose of this report is to present the results of the assessment and related groundwater monitoring. 2.0 BACKGROUND INFORMATION 2.1 Site Location and Description The project site is located at 2081 Country Club Boulevard in west-central Stockton. The location of the site is shown in Figure 1, and the site facilities are shown in.Figure 2. The site is located in a residential/commercial area, and the local topography is flat. A Chevron' gasoline station was formerly located across Franklin Street from the site, but has been demolished and is presently undergoing monitoring of soil and groundwater contamination resulting from activities at that site. 2.2 Previous Work A groundwater monitoring well was installed near the dispenser island in 1990. This well was originally labeled MW-1, but has been renamed KF-3 in this investigation. It is our understanding that Geological Technics performed routine groundwater monitoring of this well in April 1990. Total petroleum hydrocarbons in the gasoline range (TPH-g)'were detected at a concentration of 81,000 µg/1 (ppb), and benzene was detected at a concentration of 2,107 ppb. Toluene, ethylbenzene, and xylene were also detected at elevated levels. Subsequently, monitoring wells KF-1 and KF-2 were installed by Soils Exploration Service under the supervision of Upgradient in December 1994. Neither well encountered significant soil contamination, but gasoline and aromatic hydrocarbons were detected above reporting limits in groundwater samples from both wells. Groundwater monitoring since 1994 has confirmed that all three on-site wells are contaminated with gasoline-range hydrocarbons, and concentrations have tended to increase over time in the well that is farthest from the underground storage tanks (KF-2). In March, 1998, both 10,000-gallon unleaded storage tanks were removed,'along with the related plumbing. Holes were found in both tanks, and soil and groundwater in the excavation were contaminated. The results were reported by Upgradient in late March, at which time we recommended the soil investigation that is discussed in this report. 3