2008-12-16_REVISION - C1981022 (3)

Home Browse Search

Elk Creek Mine TR-60 2nd Adequacy Review 16 Dec 2008 Page 2 of 9 Division requests that the presence and quantity of groundwater inflow into the shaft be measured and reported to the Division on a monthly basis during, if possible, and after construction of the shaft.. 3. The text at the beginning of Section 9 of the TR-60 submittal states that the entire Bear Creek fan site is a small area exemption (SAE). However, the hydrology designs presented in TR-60 designate only three portions of the disturbed area as SAES. Other disturbed areas, such as the cut slopes and pad area, are not designated as an SAE on Map 2.05-El-BCA2, nor are there any Sedcad designs for them. Please revise Map 2.05-El-BCA2 to indicate that the entire disturbed area is designated as an SAE and provide appropriate Sedcad designs for the remaining disturbed areas. In the November 26, 2008 submittal, Oxbow stated that the cut slope was considered part of the recently added proposed light use road construction and, therefore, does not need small area exemption designs per Rule 4.05.2(3). As mentioned in item number 4 below, Oxbow also considers the fill areas at the inlet and outlet of the Bear Creek culvert to be part of the light use road construction and, therefore, do not need small area exemption designs either. However, the Division still requests small area exemption sediment control designs for all of the disturbed areas at this site. Rule 4.05.2(1) requires runoff sediment treatment for all areas designated as "disturbed areas". Rule 4.05.2(4), in part, excludes from the definition of "disturbed area" those areas that only consist of roads. Referring to drawing number 2.05-E1-BCA2, the light use road does not exist alone but is part of the facilities pad. Therefore, the Division considers the cut slope and fill areas at the culvert inlet and outlet to be part of the disturbed area for the facilities pad. Therefore, the runoff from all disturbed areas needs to be addressed per Rule 4.05.2. Please provide SAE designs for all disturbed areas, including the cut slope and the inlet and outlet disturbed areas of the Bear Creek culvert BCC-1. 4. Please explain why there is no small area exemption area at the south or outlet end of the Bear Creek fan site culvert, as was done at the north or inlet end of the culvert. As explained in item number 3 above, the Division requests that all disturbed areas be included in the small area exemption designs, including the cut slope and the Bear Creek culvert inlet and outlet disturbances. 5. There are no hydrology and sedimentology Sedcad designs for the proposed check dams in drainage channel BCCD-1 to show that the check dams can handle the flow and meet the settable solids limit of 0.5 ml/l. Please provide these Sedcad designs.