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COLORADO DEPARTME;VT OF PUBLIC HE-ILTH AND ENVIRONMENT, Water Quality Control Division
<br />Amendment No. 4 -Rationale. Page 3, Permit rVa. CO-0038776.
<br />• • A presedimentarian basin, The basin will consist of nvv cells for redundancy. The cells will be baffled to pretertt
<br />short-circuiting. Sludge collected will be periodically washed to the sludge drying lagoons.
<br />• A finishing pond, Ibis pond will provide polishing of the wastewater prior to discharge. This pond will be an
<br />earthen impoundment lined wit/t a geomembrane maten'a[ ro ensure water tightness.
<br />• A decant return basin and pump station. Liquid decant from the sludge drying lagoons will go to the decant re[urn
<br />basin, which serves as an equalization basin ro return this flow to the head of the facilities (the presedimentation
<br />basin).
<br />• Two sludge drying basiru. These basins will be earn/ten basins lined with concrete «rtderlain by a geomembrane
<br />material ro ensure water tightness. Since tl:e sludge will be non-toxic it can be disposed of in t/te on-site refuse pile.
<br />As stated above, supernatant will go ro 1/re decant return basin,
<br />• A srorm}vater runoff pond. This pond will receive stormsvater from the immediate disturbed area. Zlre pond will be
<br />si;,ed to contain the 25-year, 2J-hoar storm event equivalent volume. Because this pond may, on occasion,
<br />discharge ro state }voters, such discharges must be authorized under this permit. For this reason, the outfa[I will be
<br />assigned outfall number 013. It is the Division's understanding t/tat dtere will normally be no discharge from this
<br />point. Ihus, typically, reporting of this status will be the only permit requirement, unless of course discharge does
<br />occur. In such case, monitoring as specified in the permit would be necessary.
<br />These two actions, addition of outfal[ 016 and addition of outfall 017, may appear to conflict. However, it is a matter of
<br />timing. Outfal1016 will be put irsto use immediately upon approval by the permittee so that additional capacity in the
<br />two ponds is regained, ottrfall 017 will be put into service when the ,NWTF is on line. That will not occur «rttll
<br />construction is completed in early to late summer, /998. For permitting ecpediencv, both arrtfal[s are being authorized
<br />under this one permit amendnrersr even though the ,YIWTF may not be up and running jot a few months. 77ten, at a point
<br />• after the b/1VIF is operational, the permitree is ecpecred to request a permit amendment to delete mine water as a source
<br />to all systems now authorized to discharge mine water. That amendment will be handled separately at the appropriate
<br />time. After that subsequerst amendment is issued, the only outfall from which mine water will be discharged would be
<br />outfall Ol J.
<br />TV. RECEIVIeVG STRE.~41
<br />A. ldentifcation, Classification, Standards and .4ntidegradation
<br />1. /dentr~cation: T/tis facility discharges to the North Fork of the Gunnison River, Lorse Pine Gulch, Sylveste.-
<br />Grtlch ,the West Fark of Sylvester Gttlch and Minnesota Creek. The North Fork of the Gunnison River is
<br />within segment 2 of the rVortlr Fork of the Gunnison River Sub-basin of the Gunnison River Basin. Minnesota
<br />Creek is within segment S of the North Fork of the Gunnison River Sub-basin of the Gunnison River Basin.
<br />Lone Pine Gulch, Sylvester Gulch and Pre West Fork of Sylvester Gulch are within segment 6 of the North Fork
<br />of the Gunnison River Sub-basin of the Gunnison River Basin.
<br />2. lac cation: Segments 2 and S are ctassifred for the following uses: Recreation, C!¢rs 1: Aquatic Life, Class
<br />1 (cold), Water Supply; Agriculture. Segment 6 is desrgnared Use Protected and classified far the following
<br />uses: Recreation, Class 2; Aquatic Life. Class 2 (warm), Water Supply; Agriculture. A recent (June, 1997)
<br />Colorado Water Qtutlity Control Commission (CWQCC) hearing resulted in reclassification of segment 6 to
<br />include the tivater supply classification. Ibis resulted in several related standards, primarily far meraLs, being
<br />added at the same time.
<br />3. Namerir Standards: The carnplete list of standards which have been assigned in accordance with the above
<br />classification can be forted in Classifications and ,Vumenc Standards for the Gunnison River Basin (S CCR
<br />1002-35), as amended Julv 1 ~, 1997. The only water quality based standard of concern jot this action is total
<br />• recoverabfe iron, for which rite chronic standard is 1.0 mg/Q Jor segments 2 artd S.
<br />4. Anrideyradation: A review of the nett' outfalls (016, 017 and 013) for compliance with state antidegradation
<br />regulations was performed. Ourfalls UI J and 018 are etempted because the receiving water, the West Fork of
<br />Sylvester Gulch, is within segment 6 which is Use Protected: thus no further review is required. Outfall 016
<br />goes [o the North Fork of rl:e Gunnison River via a mine road culven.
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