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ENVIRONMENTS INC. MARCH 26, ZOO 1 l~I PAGE 7 11) and the specific yield of 0.2 when calculating the stream depletion numbers for the well permit for this site. Under the gravel is a layer of shale that seals it from underlying aquifers. 24. This was stated because P56G knows they will have to mitigate any impacts cause prevailing hydrologic balance. Attached is a report from Greg Roush with Leonard Rice Consulting Engi- neers addressing this request. Their analysis is very thorough and recommends methods PS&G will follow during dewatering. This report does not include an analysis of installing up gradient recharge facilities. That will be done and submitted to the Division prior to dewatering larger areas. 25. As the Division knows, gravel mines have been located in the floodplain of the South Platte River for many years and they have had little impact on the floodplain's ability to carry flood waters. The amount of gravel stored at any one time has a very small footprint in comparison to the amount of hole created by mining. The hole between the natural ground level and the groundwater table on a 50 acres portion of this site could absorb approximately 13,068,000 cu-ft of flood waters that would enter the mine. If on the other hand, one assumes the material stockpiles covered 10 acres of the plant site area and the flood depth was 3.0 feet (flood elevation 4753 feet, Plant Site elevation 4750 feet) then the stockpiles have a 1,306,8000 cu-ft foot print in the floodplain leaving a difference in our favor of 11,761,200 cu-ft. The property would actually retain more water than it does now, and actually reducing the impact a regional flood would have on surrounding land. The reclamation map shows that the internal lake separations will not be elevated above their existing grade and there are no plans to build a berm along the river. No new berms or dikes will be built on the site to impede flood waters entering or leaving it. Weld County requires PS&G to have a Floodplain Permit prior to mining the area that will address these issues. Pickett Engineering is evaluating the effects the floodplain would have on the mining operation and a copy will be submitted when available. This analysis will be the basis for the designing the protection needed on any east-west lateral divider. initially there will be no lateral dividers in the mined area, it isn't until mining ends in the Sharkey's Lake area that armoring would be necessary. 26. Using the qualifier came about because of problems I have had with the Division in the past. I was very careful to state at the setbacks along the river are Mining Setbacks so that PS&G would not be responsible for acts of nature (bank erosion) that would be very expensive to mitigate at the time of reclamation. This has happened to me before when it is time