2010-09-13_HYDROLOGY - M1981185 - Laserfiche WebLink

Home Browse Search

Inspection Report Page 2 of 4 ildcat Mining Uorporanon) during the inspection, together with documentation provided by SJBHD, DRMS and R Incorporated, indicate that the disturbed area associated with construction activities conducted by Wildcat Mining Corporation exceeds one acre. Stormwater discharge permit coverage is required for any construction activity that results in land disturbance equal to or greater than one acre, or is part of a common plan of development of sale that will disturb more than one acre. Wildcat Mining Corporation did not apply for permit coverage under the CDPS General Permit for Stormwater Discharges Associated with Construction Activity (the construction stormwater discharge permit) for the land disturbing activities observed during the inspection. The Division expects that Wildcat Mining Corporation provide a written explanation for conducting land disturbing activities at this facility without permit coverage under the construction stormwater discharge permit, and submit an application for permit coverage to Division. A copy of the permit application form is enclosed with this inspection report. The application requires that a Stormwater Management Plan (SWMP) be prepared for the facility. A guidance document on the SWMP preparation is also enclosed. Site Inspection All Best Management Practices (BMPs) mentioned in the following findings must be selected, installed, implemented and maintained according to good engineering, hydrologic and pollution control practices. These BMPs must be adequately designed to provide control for all potential pollutant sources associated with construction activity to prevent pollution or degradation of State waters. 2. It was observed during the inspection that the land disturbing activities conducted by Wildcat Mining Corporation exceeded one-acre, as provided in a, b and c, below. a. Construction of new access road o„(' County Road 124 (1.5 acres disturbed) As provided by Mr. Clements, construction of a new road for access to the May Day Mine and Mill Site facilities and the Idaho Mine was conducted in July 2008. During the inspection, Mr. Clements indicated that the portion disturbed by Wildcat Mining Corporation started approximately 148 feet from County Road 124, and ended approximately 563 feet prior to the bridge over the La Plata River. Information provided to DRMS by R2 Incorporated on behalf of Wildcat Mining Company (Idaho Mine 1210 permit amendment application I IM98851 - dated March 19, 2010: Access Easement & Area of Disturbance) indicates the total area associated with this road construction is 1.76 acres (see Attachment A). Excluding the area Mr. Clements indicated was not constructed or otherwise improved by Wildcat Mining Corporation, the resulting area of disturbance was approximately 1.5 acres (1.76 acres - [711 ft x 16 ft]/43,560 ft2). Stormwater runoff from the disturbed road flows downgradient along the path of the road until it turns to run along the La Plata River, at which point stormwater flows both downgradient along the path of the road and ultimately to the La Plata River (State waters), or is directed down the fill slope from the road construction (north side of road) to the adjacent La Plata River and wetlands area. b. Disturbance of existink access road to Mav Day No. I (Level 1) (1.3 acres disturbed) During the inspection, the inspector noted that vehicle traffic on the existing road used by Wildcat Mining Corporation to transport equipment and materials to the May Day No. 1 (Level 1) facility had created an erodible condition on the road. Vehicle traffic that increases the rate of erosion of a road surface is considered construction activity. This construction activity is contiguous and related to that documented in Finding 2.a above; therefore, it is considered part of a common plan of development or sale. As determined from maps provided by RZ Incorporated (see Attachment B), the area of this road disturbance, from the bridge over the La Plata River to the Level 1 facility, was approximately 1.3 acres [(3500 ft x 16 ft)/43,560 ft2]. The disturbed existing road is steeply sloped-the road gains approximately 600 ft in elevation from the bridge crossing of the La Plata River, to the Level 1 facility (see Attachment B). Stormwater runoff from the disturbed road flows downgradient along the path of the road or off the edge of the road to either Little Deadwood Gulch (tributary to the La Plata River) or to the La Plata River (State waters).