Laserfiche WebLink
PERMANENT IMPOUNDMENT DOCUMENTATION <br />• ]n conjunction with Ted~nical Revision TR-79, approved January 11, 2000, the CDMG approved <br />retention of Sedimentation Ponds A, B, D, and E as permanent impoundments to suppoa the <br />postmining uses of rangeland and wildlife habitat. Under applicable provisions of Rule 4.05.9(]3), <br />permanent impoundments must meet the following criteria: <br />a) The quality of the impounded water shall be suitable on a permanem basis for its intended <br />use, shall meet applicable state and federal water qualiq~ standards, and discharge of water <br />from the impoundment shall meet applicable state and federal effluent limitations and shall <br />not degrade the quality of receiving water below applicable stream standards; <br />b) The ]eve] of water shall be sufficiently stable, and the configuration of the pond shall be <br />adequate to support the intended use; <br />c) Adequate safety and access to the impounded water shall be provided for proposed water <br />users; <br />d) Water impoundments shall not result in diminution of the quality or quantity of water <br />available to water rights holders for agricultural, industrial, recreational, or domestic uses <br />except in accordance with applicable state law; <br />e) The size of the impoundment shall be adequate for its intended purposes; <br />f) The impoundment shall be suitable for the approved postmining land use. <br />• The following sections provide the required demonstration under Rule 4.05.9(13) for the approved <br />permanent impoundments. <br />ai Water Quality Suitability <br />Typical water quality for the proposed permanent impoundments can best be projected based on <br />historical pond discharge monitoring data. Active mining operations ceased in )anuarv 1993 and final <br />reclamation of mine disturbance areas was completed in 1995-]996. With renewal of the CDPS <br />Discharge Permit in July 7997, discharge monitoring requirements were reduced to flow, pH, and <br />settleable solids. Based on review of water quality monitoring records for 1995 through 2003, <br />maximum TSS and total iron values exceeded ^orma] operational effluent limits under CDPS <br />Discharge Permit COG-850037 in ]995, 7996, and 1997. In all cases, however, potential exceedances <br />occurred under documented storm-flow conditions (i.e.: > 10-year, 24-hour storm event). Under <br />these conditions, the "Active Mining Alternative Irmitauons" are applicable. Under the alternative <br />effluent limitations, the normal effluent standards for TSS and iron are suspended and compliance is <br />evaluated on the basis of a settleable solids limit of 0.5 mg/1. In all cases, discharge water quality was <br />in compliance wi[h the applicable effluent standards. Table 7 summarizes available water monitoring <br />data for the sedimentation ponds for the period 7995-2003 and provides applicable effluent limits for <br />reference. <br />Runoff water quality for newly reclaimed areas typically improves as vegetation is reestablished, since <br />increasing vegetative cover reduces erosion and sediment transport. This is consistent with the <br />findings of the Hydrologic Reclamation Evaluation previously prepared and submitted in support of <br />Kerr's Application for Partin] Phase I and Phase Il Bond Release (9/6/00, copy attached for <br />• reference). The Hydrologic Reclamation Evaluation was based on the results of revegetation success <br />monironng completed by ESCO Associates m ]999. Given the available water quality momtonng <br />data and the results of the Hydrologic Redamadon Evaluation, current and future runoff <br />contributions to the proposed permanem impoundments should meet applicable effluent standards. <br />Since the CDPS effluen[ limits are based, in part, on receiving stream standards, degradation of the <br />receiving waters has not occurred and is not reasonably anticipated to occur in the future. Reasonabh <br />