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~' <br />,4 <br />-2- <br />appear to be culverts located throughout the site which are not <br />accounted for in the permit document. Examples are the culverts <br />shown at the upper diversion ditch, the powder magazine, the <br />southwest branch of the culvert system, the bulk rock dust bin, the <br />culverts near the breaker buildings, and the parking area north of <br />Pond 'rib-1 , etc. <br />In summary, the operator should conduct a detailed survey of all <br />site culverts. A technical revision should be submitted which <br />updates all locations, sizes, gradients and calculated peak flows. <br />All culverts should be shown on a single drainage control map. <br />2. Please submit, as part of the above-referenced technical revision, <br />a detailed drainage control map. The map in our possession does <br />not appear to be an approved permit document. Our review of the <br />permit has not identified any official comprehensive drainage <br />control map. Please be sure to include all ditches, culverts, <br />berms, ponds, etc. which are located on site. Also, ensure that <br />all structures have corresponding designs to be included within the <br />permit. <br />3. The operator should provide an update on the maintenance status of <br />the upland diversion ditch which has been subject to mass <br />movement. Please provide a plan to ensure continuous function of <br />the ditch. <br />4. Please provide design details for the extra ditch located at the <br />rock storage area, along the east side of the Lower Refuse Pile <br />Area. <br />5. Based on a brief review of the permit documents, and a discussion <br />with Kathy Welt, it appears that there are no small area exemptions <br />at this site. The operator should verify that there are no such <br />exemptions. If same exist, we would appreciate a reference as to <br />the location(s), both on the ground and in the permit. It will be <br />necessary to assess the demonstrations associated with any approved <br />exemptions. <br />6. It is our understanding that all of the site sediment ponds have <br />separate principal and emergency spillway systems. According to <br />Kathy Welt, the operator is currently evaluating all pond designs <br />to ensure compliance with the new sediment pond and impoundment <br />performance standards. Your response to our renewal adequacy <br />review should report the findings of the pond evaluation. <br />VII. Bonding <br />1. Additional information is required to more accurately calculate the <br />bond. Please provide the dimensions (height, width, and depth) of <br />each of the existing structural facilities and the type of <br />construction i.e.: wood frame, concrete block, metal etc. If <br />available, also please provide the dimensions of the concrete <br />footers and the thickness of the concrete floors. <br />4687E <br />