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July 6, 2017 Monitoring Well Installation Workplan 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). 3.2. 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. Filter pack material will be placed in the well boring to a depth of 1-foot above the top of the well screen. The filter pack depth will be checked, and the volume of filter pack material considered for verifying that no bridging of filter-pack materials occurred. Each well will be gently surged during filter-pack installation (i.e., surging will occur after the filter-pack is poured into the annulus between the casing and borehole wall, but prior to the installation of the transition and sanitary seals). 3.3. Transition and Sanitary Seals The remaining annular space will be filled with a transition seal (minimum thickness of 2 feet) set on top of the filter pack, followed by a neat-cement based sanitary seal to land surface (minimum thickness of 10 feet). Bentonite will be used for the transition seal. For depths greater than 30 feet, and where water is present in the borehole, the material will be installed by use of a tremie pipe or equivalent. Where bentonite exists in the borehole in dry form, potable water will be added and sufficient time allowed for the bentonite to properly hydrate before placement of the sanitary seal. The sanitary seal will be placed within the annular space between the top of the transition seal to land surface. Sealing material shall be neat cement. Drilling fluid or cuttings from the borehole will not be used as the sealing material. All water used for sealing mixtures shall be potable. 8 Quarterly water-level and water sampling equipment and procedures are described in the Consolidated Treatment Facility semi-annual monitoring reports submitted to the RWQCB. HydroFocus, Inc. 6