2010-12-20_HYDROLOGY - M1987049 - Laserfiche WebLink

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Mr. David Bird December 15, 2010 Page Four of Five The Applicant responded as Follows: Like the Division, the Applicant also believes ground water mounding is a valid issue. The Applicant will continue to monitor ground water elevations until released from this requirement by the Division. The Applicant will use an abandoned ground water well located on the west end of the Spier's property to monitor ground water elevations under their property (see Exhibit "C-2" Sheet 2 of 7 for the location of the Spier monitoring well). Ground water monitoring data from the Spier well will be included with the rest of the ground water monitoring data and reported to the Division in the Annual Reclamation Report. Upon completion of mining and reclamation of the area around the Spier property the elevation of the reclaimed ground, including the slurry wall west of the McCann Ditch, will be on average 15 feet lower than Spier's property. Therefore, ground water mounding if any will not impact the Spier's property. Most recently, you and Tony raised concerns about ground water mounding in the context of RMCC's plans to install a low permeabilitkground water barrier along the west permit boundary line adjacent to Brighton Road. As mentioned above, the primary purpose of installing the barrier along the west side of Brighton road is to maintain alluvial ground water elevations on the east side of Brighton Road. To mitigate possible ground water mounding, RMCC will excavate a drainage ditch along the west side of Brighton Road that will act to intercept ground water. In the event that ground water intersects the invert elevation of the drainage ditch, water will drain, via the ditch, to onsite irrigation return flow ditches designed to discharge water to the McCann Drainage Ditch on the west side of the ARA property. As you know, RMCC will install a slurry wall along the west side of the newly constructed McCann drainage ditch which will act to mitigate ground water mounding east of the slurry wall. The invert elevation of the McCann drainage ditch will be approximately 20 feet lower than the Spier's home. In addition, all of the sand and gravel between the Spier's property and the slurry wall will be excavated and the pit will be backfilled with overburden to the finished grade shown on the approved reclamation plan. Tony also expressed concern about possible adverse impacts to the Spier's leach field caused by groundwater mounding. In response to that concern, RMCC will discuss with the Spier's how best to insure that their leach field continues to function properly both during mining and after reclamation. RMCC and the Spier's executed an agreement (see enclosed) in August 2009 whereby RMCC agrees to repair or replace, at its expense, any damage to their property due to its sand and gravel mining operation as approved by