4.6 PCSR 01-14-2014 - Laserfiche WebLink

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January 10,2014 Page 2 of 8 property south of 221st, the anticipated groundwater elevation should range from 954 on the east and 951 on the west. The "Excavation Plan", C2 should be modified to reflect these anticipated groundwater elevations. The applicant should also address the use of the historic high groundwater levels in establishing the excavation base grades. Response: Updated information from the Elk River Landfill, Inc.has been evaluated to update the groundwater section of the permit application and the associated Plan Sheets. Groundwater table elevations from seven monitoring wells constructed as part of the hydrogeologic study and groundwater monitoring network associated with the Elk River Landfill. Water level data was available for most of the wells for a period ranging from December 31,2002 to October 17, 2011. The location of the monitoring wells used in this evaluation,the range of water levels,and the average water table elevation for the period of record at each well is now indicated on Sheet CI, Existing Conditions. The range in groundwater table elevation was identified and the highest recorded elevations of record were used to establish the proposed minimum mining elevation. Excavation grades were revised accordingly on Sheet C2,Excavation Plan. The high water table elevations vary from approximately 957 feet above mean sea level(msl)in the east to 954.52 feet above msl in the west. Groundwater was found to fluctuate four to five feet during the period of data collection. The high water table elevations were just over two feet above the average water level over the same time period. Proposed reclamation grades are indicated on Sheet C3,Reclamation Plan.Reclamation grades have been established at a minimum of five feet above the high water table elevation and range from 5-20 feet above the high water table. (8)The plan of operation,including processing,if any,the nature of the processing and equipment, location of the processing plant, source of water,disposal of water,reuse of water,and use of explosives. Comment: The information is provided on page 5 of the application. The plan of operation does not identifi)where the phasing of mining (and reclamation) will occur and the timing for each phase. The Site should be excavated in an orderly fashion to reduce the area of open mining at any one time. In particular, it is recommended that the northern portion of the Site be reclaimed prior to initiation of mining in the new parcel proposed for the expansion. The future location of the main operations area and once, now located in the southeast corner of the northern parcel, should be identified on the (phasing)Excavation Plan, C2. The Excavation Plan should also show the locations of topsoil and backfill soils which will be used in reclamation. The soil volumes of the anticipated phases should be indicated in the application and on the Excavation Plan. Screening berms are indicated on the Excavation Plan. During the Site visit, Mr. Caron indicated that the screening plan was not completely detailed on the Excavation Plan, C-2. The details for screening berms on the north side of 221st Street should be provided. The suitability of the berms for site screening should be further demonstrated by the applicant. Details have not been provided on security fencing for the new parcel in the southern portion