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~. ! • Request for Review of Limited Mining Proposal at the Haldorson Sand and Gravel Mine M-2003-037 1. Introduction The Haldorson Sand and Gravel Mine was initially applied for as a 112 permit May of 2003. The pit is planned to mine a dry terrace deposit of gravel west of the Uncompahgre River 2-1/2 miles northwest of the town of Montrose. Protests were received and the primary issue became the hydrology of the site and the possibility of the mining affecting the hydrologic balance. In particulaz, there was a concern that the hydrology was not fully explained and that the pit could encounter water during irrigation season. The permit did not allow for ground water exposure. A Board meeting was conducted on October 30, 2003, which granted the permit but did not allow mining until one yeaz of monitoring the ground water levels through various piezometers to be installed on site. This request will review the known information that is available regazding the ground water regime on tha site and show that mining a total depth of 13 feet (10 feet of gravel and 3 feet of soil/overburden) in Phase 1 is absolutely safe and could not in any way negatively affect the users of the water upstream or downstream of the site. Z. General Ground Water Hydrology and Geology The proposed Haldorson Mine is located on a thick and extensive terrace of post- Durango gravels of Pleistocene age on what is known as Spring Creek Mesa. These gravels, as well as the entire azea, aze underlain by the extremely thick impermeable layers of the Mancos Shale. In the immediate floodplain of the Uncompahgre River, alluvial gravels of recent age are found overlying the shale and the post-Durango gravels do not exist in this area. Spring Creek Mesa has an elaborate network of irrigation canals and has been irrigated for over a century. During irrigation season, water from the ditches as well as the irrigated ]and itself enters the gravels and due to their high porosity and permeability. The water travels lower until it encounters the shale layers through which it cannot travel, such as the Mancos Shale. It will then travel along the dip of the shale to the lower terrace floodplain of the river and eventually enter the river system. After irrigation is shut off and the gravels are allowed to drain, it is likely that the entire Mesa becomes dry to the Mancos Shale. This is based on observations at other similaz sites throughout western Colorado. The levels that the water reaches above the shale depends on the porosity and permeability of the gravel, the dip of the shale, the amount of water that is