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Mr. Steve Renner • The field conditions are the same as in the New Elk Ten-Day Letter (fDL) 91-02-370-003. In that TDL there were five ponds listed; some were smaller than these cited and one was larger. As in this case, some had designs that the structures were constructed to in order to contain a specified precipitation event. The Director decided in your appeal of that case that the structures were indeed subject to the regulations. To quote from the decision: "* * * it is not necessary to resolve the question of whether the structures referenced in the TDL are sediment ponds. There is no dispute in the record that these five structures are built to retain water and sediment. In this regard, I find that they clearly fall under the definition of 'Impoundment' under Colorado Rule 103(11)(64) and, thus, are subject to the applicable design and construction requirements under the Colorado Impoundments Rule at section 4.05.9. The fact that these sediment control structures are used in connection with a small area drainage exemption or that they are designed to totally contain runoff without discharge off the permit area does not alter their need to be classified as impoundments. Indeed, Colorado rules at section 4.05.6(6) and 4.05.9(2) governing both sediment ponds and temporary impoundments speak to total containment structures by authorizing their use and allowing alternative design techniques based on demonstrations by the operator and certifications by a qualified registered professional engineer." 2 • DMG regulations require all drainage to pass through sedimentation ponds or a treatment facility. These ponds are not considered treatment facilities under the regulations. The only exemption from this requirement is for small area exemptions (SAE). This regulation requires the operator to demonstrate that drainage from the disturbed area will meet effluent limitations and water quality requirements without passing through a sedimentation pond or treatment facility. DMG is calling these areas SAE's because the drainage will meet effluent limits as a result of total containment in the sedimentation ponds. The purpose of an SAE is to exempt the drainage area from sedimentation ponds. Since the drainage must be contained in order to meet the water quality parameters, the areas do not meet the criteria for an SAE exemption, and the structures must be considered sedimentation ponds. • The fact that the ponds are excavated does not eliminate the need to comply with the design and certification requirements. The sedimentation pond regulations clearly require certification by a qualified registered professional engineer of both pond design and construction. These requirements are found at Colorado Rule 4.05.6(10) and 2.05.3(4)(a,b, and c).