2005-04-22_REVISION - M1977526 - Laserfiche WebLink

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Exhihi(G -Wafer installation of the bank stabilization, mining activities will be conducted no closer than 100 feet from the armored and stabilized bank crest without UDFCD approval. The effects of the project- related ground disturbances within the floodplain will be short-term, temporary and minimal. The proposed mining operation will conform to the requirements and guidelines provided in UDFCD's Technical Review Guidelines for Gravel Mining Activities Within or Adjacent to 100- Year Floodplains (Wright 2004). Because the operation will follow these guidelines and standard mining practices, the proposed project will result in minimal or no adverse impacts from the extraction of gravel within the floodplain. No mining activities will be performed in the South Platte River. No off-site drainage patterns will be altered and the flood storage volume will not be reduced by the proposed project. Because the new bank armor will be designed by UDFCD, no long-term adverse effects to the floodplain or floodway are anticipated to result from implementation of the proposed project. The floodway limits both upgradient and downgradient of the site are unlikely to be adversely affected by the mining operation. Wetlands and Waters of the U.S. The U.S. Department of Army Corps of Engineers (DA) performed ajurisdictional determination for the proposed Expansion Area under the Clean Water Act. The results of the jurisdictional determination (JD) were provided in a letter dated February 4, 2005 (File No. 200580059). A copy of the DA response letter is provided in this exhibit. The approved JD concluded "the DA does not have the authority to regulate work at the site, which includes the existing open water gravel pit. This pit is not waters of the US. and therefore non jurisdictional. No permft or other authorization by the DA is required for work on this property or in the existing gravel pit." The existing lake in the Expansion Area North is an artificial lake created by previous mining activities. During the biological field survey conducted on March 10, 2005, no wetlands were observed within the Expansion Area North and little wetland soil development has occurred near the existing lake. The western and eastern portions of the Expansion Area North had significant stands of woody vegetation. The western portion was previously a meander of the river. The eastern portion appears to be a depression that previously held water. Both of these areas are now dry due to the lowered water table. The biological field survey conducted on March 30, 2005 indicated a small wetland riparian area on the southwestern corner of the Expansion Area South. With the exception of this small area, no wetland soils or hydrology are present within the Expansion Area South. Soils are extremely sandy with little organic matter. Prior to installation of the bank stabilization at the Expansion Area North, no mining activities will be conducted closer than 400 feet from the top of bank of the South Platte River. After the bank stabilization is completed, the proposed mining activities will be conducted no closer than 100 feet from the armored and stabilized bank crest. Therefore, effects of the project-related ground disturbances within wetlands and riparian habitat adjacent to the South Platte River will be short-tern, temporary and minimal. ]898-Frei 112 Exhibits_(42Q05).doc Ci-4