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GENESIS ENGINEERING&REDEVELOPMENT 1.0 INTRODUCTION Genesis Engineering& Redevelopment, LLC ("GE&R")prepared this Additional Groundwater Investigation Work Plan ("Work Plan")on behalf of the William DePaoli Family in response to the California Regional Water Quality Control Board, Central Valley Region's("RWQCB")April 30, 2009 letter requiring a plan for defining the vertical and lateral extent of the groundwater impacts observed in the vicinity of Monitoring Well MW-5. This additional information, along with a statistical analysis of background concentrations for the Site, is then to be used to prepare a Proposed Groundwater Monitoring Plan for the Site. In October 2008, GE&R submitted the Site Investigation Report(GE&R 2008)to the RWQCB. Groundwater monitoring conducted as part of the Site Investigation, as well as subsequent quarterly groundwater monitoring at the Site, indicate that a number of non- metallic inorganic constituents, specifically alkalinity, calcium, chloride,potassium, sodium, sulfate,total hardness, TDS, and field electrical conductivity concentrations in downgradient Monitoring Well MW-5 consistently exceed background levels. The RWQCB has requested that the extent of the impacts identified in Monitoring Well MW-5 be defined. The DePaoli property consists of the southern 3.5 acres of the former Arcady Disposal Facility located in Stockton California("Site"). The Site location and layout are shown on Figures 1 and 2. 2.0 GEOLOGY AND HYDROGEOLOGY The DePaoli Property is located within the delta complex of the San Joaquin River. The Site is situated between the San Joaquin River proper and a distributary named the Middle River. Whiskey Slough,the water body adjacent to the Site, is connected to the river system and exhibits tidal fluctuation. 2.1 Geology The Quaternary sediments at the Site were deposited on flood plains between distributaries. At times when channels were in close proximity to the site, sediments consisting of micaceous clays, silts and sands were deposited. The suite of minerals in the sands indicates a Sierra Nevada source load. At other times the Site was remote enough from major channels so that soil deposition was minimal and peat bogs flourished. This has resulted in a stratigraphic sequence consisting of clastic sediments interbedded with I-to 3-foot thick horizons of peat. William DePaoli Property I of 7 Additional Groundwater Investigation Work Plan June 2009