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<br />29. Assuming a "worst case" catastrophic leak or spill at the site, please provide a hydrogeologic <br />analysis and/or model to determine the fate of all plausible alluvial-groundwater contaminants, <br />ie: fuel, lubricants, solvents, antifreeze, salt, etc. that may be stored or used at the pit, and <br />whether or not and how quickly ground water quality standazds may be exceeded at the permit <br />boundary. The analysis should consider such factors as dilution, attenuation, soil adsorption, and <br />dispersion of the contaminant. The Division requests that your analysis and/or modeling include, <br />buC not be limited to the following scenazios: <br />a. Ruptured tank and 100% release of fluids stored in the lazgest diesel or fuel tank located on <br />site. This can be from either a storage tank or an equipment fuel tank. <br />b. Punctured radiator and 100% release of antifreeze stored in the lazgest piece of heary <br />equipment used on site, or from a drum if antifreeze will be stored at the site. <br />c. Hydraulic line break and 100%o release of hydraulic fluid from the lazgest piece of heavy <br />equipment used on site, or from a drum if hydraulic fluid will be stored on site. <br />d. Punctured oil pan and 100% release of oil from lazgest piece of heary equipment used on site, <br />or from a tank or drum if oil will be stored on site. <br />30. The applicant will need to propose a monitoring plan, in accordance with Rule 3.1.7 that will <br />chazacterize ambient alluvial-groundwater quality and detect contamination prior to adverse <br />impacts to surface and/or groundwater users outside the permit area. The applicant will need to <br />describe, in general terms, how the operator will contain and clean up alluvial-groundwater <br />contamination if it is detected. <br />31. The applicant will need to provide a spill containment and countermeasures plan to be <br />implemented in the event of leaks or spills. Also, please provide the notification procedures to <br />be followed in the event of a spill or leak. Discuss the measures to be taken both in the event of <br />lazge spills and also housekeeping measures to be applied in the event of minor leakage or spills. <br />32. The applicant will need to provide the details of a Stormwater Management Plan for the <br />Mamm Creek Sand & Gravel Pit and any Best Management Practices (BMP's) to be employed to <br />minimize sedimentation of exposed alluvial-groundwater. This should include, at a minimum, <br />the location of the in-pit holding ponds and upland diversion ditches. Such features should be <br />shown on a revised copy of Exhibit C or a Water Features Map as specified in Rule 6.4.3(f). <br />33. The applicant states that "The operator intends on filing for a National Pollutant Dischazge <br />Elimination System (NPDES) permit from the Water Quality Control Division at the Colorado <br />Department of Health. The applicant will need to provide a commitment to demonstrate <br />approval of an NPDES permit prior to any offsite dischazge from the Mamm Creek Sand & <br />Gravel Pit. <br />RULE 6.4.10 EXHIBIT J - Ve¢etation Information <br />