2009-07-07_REVISION - M1987049 (3)

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MEMORANDUM To: Jared Ebert CC: Tony Waldron From: David Bird Date: 7 July 2009 Subject: Bromley Lakes Mine; Ready Mixed Concrete Company; M-1987-049 Review of AM -02 and McCanne Ditch Company Objection If the information provided by the McCanne Ditch Company (MDC) regarding their water right is true and correct, then it appears that MDC has a valid concern, because mining "wet" while conducting active dewatering can certainly depress the water table and could adversely impact the availability of ground water as a source of water to the ditch. It does appear that MDC has the right to protection against impairment of their water right. This problem may be compounded in the future by the Operator's intention, described in the Mining Plan, to mine on either side of the relocated ditch, then backfill east of the ditch using overburden from the various Ready Mixed mining operations in the area. If overburden material is used as backfill, it may create a situation (similar to that which occurred recently at the Speer Mining Resource site) where the backfill is lower permeability than the pre-existing gravel that will be mined out. This might create a situation at the Bromley Lakes site in which the fill inhibits the ground water flow into the ditch, necessitating some sort of augmentation to maintain the minimum flows in the ditch. If the MDC water right trumps all and the Operator if required to protect the MDC water right, then the Operator may have to revise the mining and reclamation plans to ensure that the backfill material upgradient of the ditch has adequate permeability so as not to restrict ground water flow to the ditch. Here are some options that can be considered. There may be more options than this list, and the 2nd option is a short-term option for use during mining rather than in the post -mining situation, but this is what I have come up with so far: 1) Require the Operator to provide augmentation to MDC for as long as needed. This may be impractical because the augmentation may be needed in perpetuity, and the Operator probably wants to release the site after mining and reclamation are complete. However, if post -mining land use includes water storage, perhaps a portion of the impounded surface water could be diverted to provide augmentation. 2) Require the mine to operate without a slurry wall and mine wet, such that dewatering would be required during mining, for which a Substitute Water Supply Plan would likely be needed from the State Engineer during and after mining. This scenario would allow the ground water to flow