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0 <br />TETRA TECH RMC <br />Page 2 <br />Ms. Kate Pickford <br />March 20, 2003 <br />SEED MIX LOCATION AREA (ACRES) <br />Mesic Areas Reservoir shoreline 34.7 acres <br />Water's Edge Pond shoreline 3.3 acres <br />Wet Meadow Wetland areas - only if necessary. It <br />is anticipated the wetland vegetation <br />will establish without any seeding. 2.2 acres <br />Upland Future development areas and land <br />outside of slurry wall. 10.9 acres <br />6. Hall-Irwin intends to bond for 100% of the slurry wall around pod 2. Hall-Irwin <br />has submitted a temporary substitute water supply plan and well permit <br />application to the Office of the State Engineer (SEO) for review and approval. <br />This will allow Hall-Irwin to dewater and mine pod 1 (which has no slurry wall), <br />process the material and expose groundwater for wash ponds in pod 3. <br />Rule 6.4.7 Exhibit G -Water Information <br />Hall-Irwin will acquire the NPDES permit prior to discharge of any water from <br />the site. <br />8. Hall-Irwin will install approximately 9 monitoring wells or piezometers located <br />strategically throughout the site (refer to Mining Plan Map for locations) and <br />check them monthly both before and after mining has commenced to establish a <br />baseline. <br />9. This site is within the Big Thompson alluvial aquifer. The dewatering of pod 1 <br />may result in the lowering of the water table in the surrounding alluvial aquifer. <br />(The remaining pods will have slurry walls and will not cause a cone of <br />depression.) Hal]-Irwin will obtain agreements with all well owners within 600' <br />of the site and commit to fix any well production problems that arise as a result of <br />the mining operation. <br />During mining, the water table just outside the mining area is lowered to near the <br />bottom of the pit. The water Cable rises away from the pit. At some distance <br />from the pit, the water table returns to its background level. The distance from <br />the edge of the pit to the water table's background level is known as the "zone of <br />influence." The distance of the zone of influence is a function of many factors, <br />including: saturated thickness of the aquifer, hydraulic conductivity of the <br />aquifer, and the presence of sources of recharge such as irrigation ditches, rivers, <br />lakes, irrigated fields, sources of discharge (wells), or impermeable barriers such <br />as bedrock, valley walls, and lake liners. Precise measurements of the zone of <br />influence are difficult to obtain because of the variability (seasonality) of <br />