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<br />-3- <br />Towards the end of mining in the west pit, much more <br />to whether or not the pit will fill with water after <br />_ may be useful to wait until that time to evaluate the <br />1~ ~ demonstrated at that time that the water-bearing zone <br />dewatered thoroughly, then the reclamation plan will <br />presently proposed. However, if it appears that the <br />been depleted and will fill the pit, then one of two <br />`J <br />data will be available as <br />dewatering eeases. It <br />se data. If it can be <br />around the pit has been <br />probably work as <br />local aquifer has not <br />things should be done: <br />1. Areas around the anticipated final water level should be backfilled to <br />3H:1V slopes for five feet above water to 10 feet below, as would be <br />required of any ground-water lake; or <br />2. The pit should be backfilled to above the anticipated water level with <br />waste rock, retopsoiled, and revegetated. <br />One of these contingency plans should be bonded for. <br />Also, the pit is located out of the 100-year, 24-hour floodplain. However, <br />the pit is located little more than 100 feet from the present channel of the <br />Rito Seco and is probably within the 500-year floodplain. If ar,c when the <br />Rito Seco breaches into the pit, the creek water would probably :,~t exit the <br />pit but rather would fill it to a higher level. The creek therefore would no <br />longer provide water to downstream users and aquifers. This would be a <br />significant impact to the local hydrologic balance. I suggest that the county <br />road relocation which will separate the Rito Seco floodplain fror~ the pit area <br />be built to withstand a more substantial flood event, such as a :-00 year <br />storm. The road foundation could be built and/or reinforced with waste rock <br />from the west pit. I assume that continued maintenance of the county road <br />would ensure the effectiveness of this reinforcement after reclamation is <br />complete. <br />2263E/pcm <br />