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09/09/94 15:19 <br />. <br />$505 7882809 <br />• <br />OS)d ALBUO FO ++~ CO/DMG ~ 002/004 <br />• <br />Technical Interpretation-- Dozer Basins <br />Western Support Center, August B, 1994 <br />The regulations at 30 CFR 701.5 state that the definition of <br />impoundment means "all water, sediment, slurry or other liquid or <br />semi-liquid holding structures and depressions, either naturally <br />formed or artificially built." In this context, it would appear <br />that dozer basins meet this definition and therefore would have <br />to meet the requirements of 30 CFR 780.25, 816.49 and perhaps <br />816.46 in certain circumstances. <br />This definition of impoundments is broad and does not include a <br />size or a function criterion. The regulations at 30 CFR 81G,56 <br />(POStmining rehabilitation of sedimentation ponds, diversions, <br />impoundments, and treatment facilities) also apply the definition <br />broadly; it states: "(a] small depression which is capable of <br />holding water would be an impoundment" in a reclaimed area, and <br />would have to meet permanent impoundment requirements (48 F12 <br />x4002). <br />However, it would appear that other regulations would allow the <br />regulatory authority (RA) to consider the purpose of the <br />structure when making a decision as to whether or not it is <br />regulated as an impoundment. FoY example, the preamble to the <br />final rule 30 CFR 816.45 (4a FR 15158) described "sediment <br />control measures to be utilized in conjunction with sedimentation <br />ponds as best technology currently available to achieve and <br />maintain the water quality standards of the Act" suggesting that <br />sediment control measures (SCM's) should be considered something <br />other than impoundments (emphasis added). The rule contains a <br />list of SCM's that includes check dams and dugout ponds, measures <br />that inherently impound water and would otherwise meet t]te broad <br />definition of an impoundment, <br />Thfs discretion is also supported by the preamble discussion <br />contained in the September 26, 1983, rulemaking, approving the <br />definitions o! Impoundments and Sedimentation Ponds (48 FR <br />43996). With respect to sedimentation ponds, this fina] r~lle <br />stated that "the definition (of sediment pond) has been <br />simplified .by rewording, removing reference to 816.46 [Hydrologic <br />Balance: Siltation structures], which was unnecessary and <br />removing the list of secondary sediment control structure::, <br />Secondary sediment control structures, such as straw dikes, <br />riprap, check dams, or mulches, are not impoundments and thus are <br />not sediment ponds under the new definition, even with an express <br />exc]usion." This listing oP secondary measures as well as dugout <br />F,ondo-:, sediment filters ar.d other measures that reduce overland <br />flow velocity, reduce volume or. trap sediment are now Contained <br />in 30 CFR 81G.a5, Hydrologic balance: Sediment control measures. <br />'To be consistent with the°:e L'ulc:s, dozor. basins should be treatec <br />as a SCM only so long as they meet the above stated rcquir~ement.s:. <br />