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Downgradient Water Well Sampling Plan Austin Road Landfill,San Joaquin County Page 2 shallow zone. A shallow zone groundwater flow map based on December 2008 data is included as Figure 1. The direction of groundwater flow in the deep zone can be determined using the recently-installed deep monitoring wells combined with data from previously-existing wells AMW-6 and AMW-7, which have screened intervals of+ 160 feet below ground surface and therefore monitor the deep zone. Attachment 2 provides a brief summary of drilling and monitoring well installation activities associated with the installation of four new deep zone monitoring wells. Using December 2008 water level data, the direction of groundwater flow in the deep zone is toward the north(Figure 2). To help identify all downgradient water wells within 4,000 feet of the point of compliance, Herst & Associates, Inc., on behalf of Forward, Inc., completed a California Department of Water Resources (DWR) Well Completion Report Release Request (Request) for water supply wells in the vicinity of the Austin Road Landfill. Pursuant to DWR procedures,well completion reports may only be released as a part of an environmental study conducted pursuant to a regulatory agency order, and a Request therefore requires the authorization of the agency that ordered the study. Accordingly, on December 3, 2008, Herst & Associates, Inc. submitted the completed Request to the California Regional Water Quality Control Board (RWQCB), Central Valley Region in order to obtain the authorizing signature. Herst&Associates,Inc.received the signed Request from Howard F.Hold with the RWQCB on December 8, 2008. Herst & Associates, Inc. submitted the signed Request to the DWR on December 8,2008. To provide an overly conservative database of wells,Herst&Associates, Inc.requested from DWR records for all wells,regardless of use,within a 1-mile radius encircling the Austin Road Landfill. Herst & Associates, Inc. received a response from DWR consisting of TIF files of historical well completion reports on CD-ROM. A copy of the CD-ROM provided by the DWR is provided in Attachment 3. The data provided on the CD-ROM were used to locate water wells. Those wells located within 4,000 feet downgradient of the Austin Road Landfill (that is, north or northeast of the Landfill) are shown on Figure 3. According to the DWR records, there are three irrigation wells located within 4,000 feet downgradient of the Austin Road Landfill (Figure 3). However, as shown on the Water Well Drillers Reports (Attachment 4), all three wells are registered as irrigation only, not domestic. Accordingly,they would not be used as a source of drinking water. Although not identified in the information provided by the DWR, there are two additional known domestic wells within 4,000 feet downgradient of the landfill. These are identified on Figure 3 as wells 7898 and 8106A(which represents their street addresses). Although neither well was identified by the DWR and therefore are apparently unregistered, these wells are sampled on a regular basis by Austin Road Landfill,and the homeowners at these locations are provided with replacement drinking water by the City of Stockton. In summary,there are no additional domestic or municipal water supply wells located within 4,000 feet downgradient of the Austin Road Landfill that are not already sampled and not already provided with replacement drinking water by the City of Stockton. Accordingly, the CAO provisions for providing access request notices to nearby well owners, sampling and analyzing additional domestic wells, and supplying replacement water to affected well owners do not apply. A sampling report as specified in the CAO is therefore not required. Pursuant to the CAO,a copy of this Plan will be placed in the facility's Operating Record. •