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September 30, 2015 Monitoring Well Abandonment and Installation Workplan 4. Monitoring Well Design As stated in the WDRs,groundwater monitoring wells are to be designed and sited to ensure that water quality at storage pond sites and land application areas is adequately characterized and any potential water quality impacts from the discharge are detected.The wells shall yield samples representative of the uppermost portion of the first encountered groundwater underlying the proposed monitoring site. General monitoring well design is illustrated in Figure 4(above ground completion).This design is consistent with SJCEHD and State of California Monitoring Well Standards.A description of the monitoring well design includes: (1) the well casing,perforated over the targeted depth interval for monitoring; (2) the annular spacing between the perforated well screen and borehole,filled with a filter pack; (3) a transition seal placed on top of the filter pack;and, (4)a sanitary seal which extends upwards from the top of the transition seal to land surface.Additional details on monitoring well casing,filter pack,seals,and completions are described below. 4.1. Well Casing The well casing will be ASTM,API and/or AW WA approved.The casing diameter will be 4 inches to provide adequate clearance for water-level measuring instrumentation,either electronic sounders or pressure transducers,and submersible pumps to collect water samples.8 The perforated length (well screen) shall be selected to provide samples representative of the uppermost portion of the first encountered groundwater and produce sufficient yield for adequate purging and sampling.The well slot size (perforation size)shall be selected based on water-bearing sediment texture encountered,but shall not be smaller than 0.010 inch slotted screen.All well-casing joints will be flush-threaded and watertight. The bottom of the well will include a minimum 1-foot solid casing sump,sealed with either a flush-threaded or slip cap (if a slip-cap is utilized it shall be secured with threaded stainless steel screws). 4.2. Filter Pack The annular spacing between the well casing and formation will be filled with clean filter pack material matched to the slot size of the well screen (#212 sand,which was used for the existing monitoring wells located at the site).The objective for the filter pack material is to exclude the entrance of fine silts,sands,and clays into the monitoring well yet provide sufficient well-yield for effective well purging and sampling.Filter pack material will be nonreactive,not degrade or consolidate after placement,and obtained from clean sources and properly packaged for handling,delivery,and storage. s Quarterly water-level and water sampling equipment and procedures are described in the Crossroads W WTF quarterly monitoring reports submitted to the RWQCB. HydroFocus, Inc. 7