Laserfiche WebLink
Rifle Gravel Pit#1 August 2021 <br /> 8.0 Exhibit G - Water Information <br /> Exhibit G, Figure 18 depicts the rivers, creeks, water courses, and ditches on the site and <br /> adjacent lands. <br /> Mining of an aggregate deposit like the Rifle Pit will involve affecting local groundwater and <br /> surface water. During active mining operations, local dewatering efforts will pump <br /> groundwater to allow for aggregate mining. <br /> Scott Contracting, Inc. will support the mining dewatering needs using 1 to 3 wells (plus <br /> temporary drains and pumps to capture incidental inflows). <br /> 8.1 Pit Dewatering <br /> Exhibit D1, Figure 10 depicts a typical cross-section during mining, including the use of a <br /> dewatering floor trench and dewatering pump to remove water from the pit floor during <br /> mining. Water pumped from the pit floor will be discharged to the dewatering pipeline. <br /> Scott Contracting, Inc. negotiated a temporary license agreement with the owner of the <br /> neighboring Shideler property (Parcel 217908100527) to the east that will allow Scott <br /> Contracting, Inc. to bury a 12" dewatering pipeline that will collect and convey pumped <br /> dewatered water to the Colorado River. This pipeline will have an energy dissipation <br /> structure upstream of the discharge point to the Colorado River and an armored outfall to <br /> prevent erosion and sedimentation discharges into the Colorado River. <br /> Scott Contracting, Inc. will apply for coverage under Permit No. COG603000 (Discharges <br /> Associated with Subterranean Dewatering or Well Development) or Permit No. COG608000 <br /> (Discharges to Surface Water from Well Development and Pumping Test Activities) to <br /> manage dewatered water. The specific permit will be determined once the water is sampled <br /> and analyzed. <br /> The trenching and installation of the proposed dewatering pipeline will create temporary <br /> impacts to federally jurisdictional wetlands located on the Shideler property (Parcel <br /> 217908100527) and will also require a permanent outfall structure on the bank of the <br /> Colorado River, which will constitute a permanent impact to that jurisdictional water. A range <br /> of alternatives has been considered for this project and every effort has been made to avoid <br /> the discharge of dredged or fill material into waters of the United States. However, there are <br /> no practicable alternatives that avoid a minor and temporary filling of wetlands, which have <br /> been minimized to the extent possible by careful selection of the proposed pipeline route. <br /> An aquatic resources report and wetland delineation will be submitted to the ACOE in <br /> support of a nationwide permit application 39 (NWP 39) for Commercial and Institutional <br /> Developments. The NWP 39 application will encompass the initial pit development stages <br /> (Stages 1-2) and the dewatering pipeline. All impacts from the dewatering pipeline are <br /> temporary; in accordance with NWP 39 conditions, during installation in wetland areas <br /> heavy equipment will work on mats to minimize surface disturbance, and topsoil will be <br /> segregated and reapplied following pipeline installation. No changes are proposed to the <br /> existing hydrologic conditions on the Shideler property; therefore, the wetland conditions will <br /> quickly re-establish in the pipeline route. The NWP 39 will be acquired prior to construction. <br /> 41 <br />