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... Wright <br /> Environmental <br /> Services, Inc. <br /> May 9, 1995 <br /> MAY 12 1995 <br /> M & M Automotive <br /> 60 East Tenth Street <br /> Tracy, CA 95376 ENVIRONMENTAL PR � EICESLT <br /> Attn: Mr. Larry McLean <br /> Subject: Proposal for Supplemental Groundwater Investigation <br /> M & M Automotive Facility <br /> 60 E. 10th Street, Tracy, CA 95376 <br /> Dear Mr. McLean, <br />' Thank you for the opportunity to provide environmental services to further define <br /> the extent of soil and groundwater contamination from the area of- the- former <br /> underground gasoline storage tanks at the above referenced site. This proposal <br /> details the procedures and estimated -cost to collect a maximum of eight soil and <br /> groundwater samples from survey probes to be excavated in an- apparent <br /> downgradient direction of the former underground tanks. Included in this proposal <br /> is the preparation of work plan, detailing the methodologies and procedures of the . <br /> supplemental investigation. Preparation of a workplan has been requested by San <br /> Joaquin County Public Health Service-Environmental Health Division (PHS-EHD) <br /> following their review of recent subsurface work performed at the site. <br /> BACKGROUND <br /> One 550-gallon underground gasoline tank gasoline, one 285-gallon underground' <br /> gasoline tank, and the associated pump and piping were removed from the site on <br /> November 12, 1991 by Tank Protect Engineering. Analyses of soil samples collected at <br /> approximately, 9 feet below ground surface at the bottom of each underground <br /> storage 'tank (UST) detected a maximum of 7,400 parts. per million (ppm) of total <br /> petroleum hydrocarbons as gasoline (TPHG) and 44 ppm benzene. Approximately 8' <br /> cubic yards of soil was excavated. The excavation was then backfilled and resurfaced <br /> with asphalt. - In December 1994, Wright excavated seven exploratory soil borings and <br /> installed three groundwater monitoring wells in an effort to determine the lateral <br /> and vertical extent of contamination in the area of the former tanks. The results of <br /> the subsurface investigation indicated that an estimated 130 cubic yards of soils in <br /> and around the former tank area appeared to be affected (Figure 2). Groundwater' <br /> was also found to be impacted with petroleum hydrocarbons around the former tank <br /> area. The limit of contamination appears to be defined to the east, west, and south of <br /> the former tank area. However, the 'extent of contamination to the north of the <br /> former tanks (into and across 10th Street) has not been defined. The three existing <br /> monitoring wells are currently being monitored on a quarterly basis.. <br /> SCOPE OF WORK- TECHNICAL APPROACH <br /> The extent of soil and groundwater contamination needs to be further defined in the <br /> area north of the former tanks extending into and quite possibly across 10th Street. <br /> The scope of work will include revising a Site-Specific Health and Safety Plan, <br /> obtaining the appropriate permits from PHS-EHD, install up to eight soil boreholes <br /> d <br /> using direct push and Hydropunch'�' technology; and collecting and analyzing the. <br /> soil and groundwater samples from selected locations using the attached Wright <br /> 4220 Commercial Dr. #5 • Tracy, California 95376 <br /> Telephone (209) 833-0758 • Fax (209) 832-5152 <br />