2001-12-11_PERMIT FILE - C1982056A (3)

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COLOP.ADO DEPARTMENT ~ . HEALTH, Woter Quality Control Division Rationale, Amendment No. 1 Pagt 2 Permit No. CO-0027154 • IIL RECEIVING STREAM.• A. Identjfieation, C/ass(jlcation and Standards Identification: The facility discharges go to Foidel Creek, Fuh Creek, and Middle Creek These receiving waters, including TYout Creek, are within segment 13b of the Yampa River subbasin, Upper Colorado River basin. 2. Classification: Segment 13b is classified jot skit following uses: Recreation, Class 1; Aquatic Life, Class 1 (Cold); Agriculture. 3. Numeric Standards: The applicable standards far segment 13b which have been assigned in accordance with the above classiflcatians can be found in 3.3.0 Classifications and Numeric Standards for the Upper Colorado River Basin (S CCR 1002-8J. Refer to the previous renewal rationale for junkier discussions regarding the applicablc water quality standards. IV. PURPOSE OF A.MENDMENT.• This amendment it being made ro: I) change the compliance point for collection of grab samples for outfall 005 from the flume to the end of the discharge culvert; and 2J include an additional wastewater source, mine drainage water, to outfall 007. • V, DISCUSSION OF AMENDMENT: In a letter dated April 12, 1993 from Marcus Middleton of Cyprus Yampa Valley Coa! Corporation (CYVCC), the permittee requested that the two above changes for outfatls 005 and 007 be mod fled in this permit. These two requesu are discussed in mare detail following. CYVCC requested that the compliance point for collection of grab samples be changed ro the to the end of the discharge culvert far autfall 005. This will avoid any potential effecu from the adjacent small area aemptaon flow drainage sources upon samples collected at this outfall The small area etemption waters are drainages from the adjacent rock falter, haul road(s), and embanbnent areas. The durance that the sampling location wilt be moved from the flume to the culvert u approximately 30 to 40 feet. CYVCC also requested that the permit be amended to allow for the discharge of mine drainage via outfall 007. Mine drainage it currently either discharged via outfall 005, or u diverted ro the spoil aquifer adjacent to outfall 007 and recycled far use underground. Thu amendment would allow for the routing of overflow containing mine drainage from the spoilt aquifer to outfa11007, along with direct roaring of mine dscharge to outfall 007. Essentially, the only difference between the existing limitations for outfalu 005 and 007 it that limitations exist for potentially dissolved silver for outfall 005, and monitoring for this parameter u required for oaufali 007. This was based upon previous comments prior to issuance of the renewal permit (refer to pages 25-26 of the renewal rationale, dated February • S, 1993). Since the previous monitoring data for silver at outfall 007 has had concentrations much below the silver permit limiu far 005 (with most 007 concentrations below or at the minirmun detection level used), this permit amendmem will cominue with monitoring for potentially dissolved silver at outfall 007. Also, since it is likely that the actual