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i 133 WA Ce^[er Varknay, iwle 100 P PdSdn'Jn, ~~? Environmental Site Investigation report, dated August 11, 2008, identified total ~asoe-3.o. petroleum hydrocarbons in the diesel range (TPHd) in a groundwater grab sample p~9zsasa noo from the first (shallow) encountered aquifer at a concentration of 49,000 micrograms }1925 ~aa sa3s per liter, and recommended collection and analysis of soil and groundwater samples kleinfelder.com from four additional soil borings at the Site. ACEH approved the recommendations and requested an addendum to the August 11, 2008 report to include one additional soil boring to a minimum depth of 60 feet in order to assess the vertical extent of hydrocarbon impacts to soil and/or groundwater. SCOPE OF SERVICES Kleinfelder proposes to perform an additional environmental site assessment in order to assess the extent of TPHd concentrations in soil and groundwater. Addendum to Environmental Site Investigation Kleinfelder will prepare an addendum to the Environmental Site Investigation report dated August 11, 2008, describing the methods to be used to collect a groundwater __ grab sample from a deeper aquifer beneat# the- Site:- The- methods. employed- wilF - minimize the possibility of down-hole movement of groundwater and cross contamination of deeper water-bearing zones. Permitting and Coordination Kleinfelder will schedule site access with the City, and will coordinate the field work with our subcontractors (e.g. analytical laboratory, and drilling subcontractor). We will obtain drilling permits from the Zone 7 Water Agency for the soil borings. Kleinfelder will notify Underground Service Alert (USA) of our soil boring locations at least 48 hours prior to the start of field work. We will also retain a private utility .locating company to check for underground utilities in the vicinity of the soil boring locations. Kleinfelder will update an existing site-specific health and safety plan for the proposed Additional Environmental Site Assessment. Soil and Groundwater Sampling Soil and groundwater samples will be collected from five soil borings utilizing atruck- mounted direct-push (GeoProbe) drilling rig. Four borings will be continuously cored to a depth of approximately 40 feet below ground surface (bgs). One groundwater grab sample will be collected from each boring using the methods described below. One boring will be continuously cored to a depth of approximately 60 feet bgs using the dual tube system to isolate the first encountered aquifer and avoid cross contamination of the lower aquifer. Discrete groundwater grab samples will be collected from the upper and lower water-bearing zones. In the event that a total depth of 60 feet bgs cannot be reached using the above-described methods, the 01002PROP / (PLEBP294.doc) /jmk Page 2 of 9 November 11, 2008 Copyright 2008, Kleinfelder