SITE INFORMATION AND CORRESPONDENCE

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Section 2 Groundwater Monitoring Well Installation 2.1 MONITORING WELL LOCATIONS AND RATIONALE The purpose of groundwater monitoring is to provide a measurement of compliance with regards to the State Antidegradation Policy and with respect to wastewater treatment and disposal activities. An effective groundwater monitoring network will provide at least one clearly "up- gradient" and a minimum of two "down-gradient"wells. Furthermore,the monitoring network should be designed to allow for normal seasonal fluctuations in groundwater elevation and horizontal groundwater gradient direction,while taking into account water quality effects associated with dilution, such as wells of large diameter and/or with excessive lengths of well screens. Additional wells are sometimes required when strong seasonal changes in groundwater gradient are suspected and when hydrogeologic boundaries, or other conditions, are encountered. Such wells must be designed and located to provide representative samples of groundwater beneath the wastewater treatment, storage, and disposal sites and not create a vertical conduit for contamination of deeper groundwater. Figure 2-1 illustrates the location of the proposed monitoring wells (PMW-5,PMW-6, and PMW-7),positioned such to augment the exiting groundwater monitoring network and provide an effective means of measuring facility compliance with regards to potential groundwater degradation. These well locations were chosen based largely on groundwater flow direction, known accessibility constraints, location of surface water features, and historical effluent irrigation disposal operations, as well as,the recommendations presented in the July 6, 2007 technical memorandum Woodbridge Sanitary District Hydropunch Investigation Summary Results, (Appendix A). Woodbridge Sanitary District April 2008 Groundwater Monitoring Well Installation Workplan WBSD07-002 2