Laserfiche WebLink
Coulson Excavating Company, Inc. -Stroh Gravel Pit <br />Exhibit G -Water Information <br />The proposed pit is located on the northeastern border of the Big Thompson Watershed <br />Basin. The local tributary watercourse is the Big Thompson River, which runs <br />immediately north and east of the site. Several irrigation trenches run through and around <br />the site, and an imgation ditch (Hillsboro ditch) runs south of the proposed area. In <br />addition, a shallow unconfined aquifer occurs at the site and adjacent properties at <br />approximately 7 ft to 8 ft depth from the surface extending down to approximately 20 ft <br />to 25 ft below ground surface. The local groundwater flow direction is north. See Exhibit <br />C for the location of the river and ditches. <br />The operation is expected to affect the groundwater/surface water system by exposing a <br />small amount of groundwater to the atmosphere. The only other water loss from the <br />operation will be pore water taken with the mined product. <br />Water pumped from de-watering trenches will be piped to asediment-settling pond <br />located at the northwest border of the project area. Pump rates for the dewatering <br />trenches are expected to be approximately 0.15 - 0.72 MGD. The water will be allowed <br />to naturally seep into the Big Thompson River and a siphon will account for any <br />overflow. The dewatering effluent will be regularly sampled as mandated by National <br />Pollutant Discharge Elimination System (NPDES) protocol. Soil stockpiles will be <br />seeded, crimped, mulched, and bordered by silt fences to avoid soil erosion and <br />degradation of Big Thompson River water quality. See Exhibit D for structure locations. <br />Coulson Excavating Company has applied for a NPDES permit from the Water Quality <br />Control Division at the Colorado Department of Health for gravel mining operations of <br />this pit. <br />H:\Project Data\Gravel Projects\Stroh\word\DMG\Exhibit G.doc <br />