SITE INFORMATION AND CORRESPONDENCE FILE 1

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INVITATION FOR BID and BID SPECIFICATIONS Nomellini Construction Co. 1045 West Charter Way, Stockton, California I. INTRODUCTION Nomellini Construction Co. is requesting bids from qualified environmental consultants for design, installation, operation and monitoring of a hydrocarbon-impacted soil and ground water remediation system at 1045 West Charter Way in Stockton, California. The approximate location of the site is illustrated on Figure 1 . A plan of the site is illustrated on Figure 2. 11. BACKGROUND The following is a summary of investigation work previously performed at the site: • In August 1988, two 1 ,000-gallon gasoline underground storage tanks (USTs) were removed from the site. Following tank removal activities, soil samples were collected beneath both tanks and submitted to a state certified laboratory for analysis of petroleum hydrocarbons. Analytical results of soil samples collected from beneath the USTs indicated that substantial petroleum hydrocarbon concentrations 1,vere present in soil samples. • The tank area was re-excavated in November 1988 . Soil was removed from the former UST area to a depth of approximately 19 feet below site grade (bsg). Soil samples were collected from the excavation and screened for organic vapors using a photo-ionization detector (PID). Organic vapor readings indicated that petroleum hydrocarbons were present at depths in excess of 19 feet bsg. As a result, the excavation was backfilled and a preliminary site assessment initiated. • Between May 1989 and December 1994, a total of nineteen soil borings were advanced at the site; nine of the nineteen soil borings were completed as two-inch diameter monitoring wells (MW- 1 through MW-9). Extensive petroleum hydrocarbon-impacted soil and ground aa water, including free product, was encountered during assessment of the site. • In July 1995, one dual-purpose soil vapor extraction/ground water extraction well (EW4 ), and two soil vapor extraction wells (VW. 1 , VW-2) were installed at the site. In August 1995 , an 8-hour soil vapor extraction (SVE) pilot test was conducted at the site. The pilot test was performed to provide vapor extraction data for proper system design of a remediation system. • Between February 1991 and February 1997, eleven ground water monitoring/sampling events were performed at the site. During this time, concentrations of dissolved petroleum hydrocarbons indicated an increasing trend from the "core" area wells, and decreasing a trend from the perimeter wells.