2023-07-12_PERMIT FILE - M2022048 (2)

Home Browse Search

ENVIRONMENT, INC. PAGE 5 L.G. EVERIST, INC.-WEST FARM RESERVOIR ADEQUACY RESPONSE 02 JURY 10,2023 lowest numerical standard for that analyte in those tables. Justification must be provided for removing any analytes from the baseline sampling program. DRMS certainly does not object to the collection of additional parameters(such as alkalinity, calcium, magnesium,potassium and sodium as included in Table 3) which may be useful for the purposes of groundwater chemistry. Responses to points 22a thru 22n have been addresses in the revised Groundwater Sampling Plan (GSP) and the Groundwater Monitoring Plans . Copy attached. A revised Map Exhibit 61 - Water Wells within 200 ft. making the well designations uniform is attached. 23a) Based on the information provided in the Groundwater Elevation Model, and the shallow pre-mining depth to groundwater(less than 5'b.g.s. in MW7), DRMS will require the installation of an underdrain as depicted in Figure 5 of the Groundwater Elevation Model along the southeast area of the permit to maintain the prevailing groundwater levels in this area. Please provide detailed design/installation specifications for this underdrain and a commitment to install the underdrain in conjunction with the slurry wall installation for Cell 1. L.G. Everist will commitment to installing the under drain in conjunction with the slurry wall installation for the Phase 1 reservoir from the base of the terrace to the east along the southeast side. The approximate location of the under drain is shown on the Exhibit F - Reclamation Plan Map revised 7-06-2023. It is premature to actually provided the design and installation specifications until the exact location of the slurry wall will be known . The design information will be provided as a Technical Revision prior to installation of the under drian. In general the plan is to use a 12 inch diameter perforated PVC pipe that will be placed along the outside of the slurry wall at an elevation consistent with the average historic groundwater elevation along the south side of the proposed slurry wall. The pipe will be surrounded with gravel bedding and then covered with native backf ill. The pipe will be sloped so it drains to the east and either empties into the river or the irrigation return flow ditch that will run north along the east side of the Phase 1 slurry wall, emptying into the river. 24a) DRMS concurs with the placement of the additional groundwater monitoring wells shown in Exhibit G, and the Groundwater Quality Monitoring Plan. Please commit to providing well construction diagrams for all currently installed wells, and proposed wells upon installation. A Typical Monitoring Well diagram for the existing monitoring wells is attached. L.G. Everist will commit to providing well construction diagrams for the proposed monitoring wells when they are installed.