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However, in the absence of actual discharge samples, the Division relies on <br />pond performance estimates to ensure that water quality is maintained. This <br />information is typically included in the permit application and is developed using <br />accepted hydrologic and engineering principles. The Division was unable to <br />locate any information in the permit application that estimates sediment effluent <br />concentration resulting from a storm event. Quantitative data available in the <br />permit application only gives an estimate of total sediment delivered to the pond <br />and total storage (active and passive) volume available in the pond. <br />Given the difficulty in collecting actual discharge samples, the Division requires <br />that calculations estimating pond performance during and after a storm event are <br />included in the Raton Creek permit application. Given the as-built condition, the <br />Raton Creek sediment pond will discharge during and after a storm event. Using <br />the as-built pond configuration, please submit the necessary calculations <br />estimating the efFluent concentration for settleable solids from the 10-year storm <br />event. This permit material should be submitted under the pending permit <br />renewal no. 4 (RN-04) and in the form of permit text, SEDCAD or other <br />documentation, and maps as required. <br />2. Also, regarding the sediment pond at the site, the permit application states on <br />page 350 that "modification to the pond will be made to meet the appficabfe <br />regulations for permanent retention." The regulatory requirement is Rule 4.05.17 <br />Postmining and Rehabilitation of Sedimentation Ponds, Diversions, <br />Impoundments, and Treatment Facilities. Please review this Rule when <br />addressing the issue of pond performance and sediment storage and cleanout. <br />3. The fieldwork that EFMC committed to complete by August 31, 2002 was not <br />entirely completed, The south access road ditch grading and the straw bale <br />repair at the west end of the 100-year ditch was noted as incomplete during the <br />August 29, 2002 inspection. This work must be completed by the end of <br />September 2002 to avoid enforcement action. <br />Please submit information requested no later than September 30, 2002. If you have <br />any questions, please call me. <br />Sincer ly, ~Q~ <br />Kent Gorham <br />Environmental Protection Specialist II <br />CC: Dan Hernandez <br />