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;OLORADO DEPARTMENT OFPUBLIC HEALTH AND ENVIRONMENT, Water Qua7iry Control Division 'niiona/e -Page 7, Perini[ No. CO-0038776 For Outfail 017, with the change stream standards, chronic WET would now apply. Previously, MCC was required to monitor fgoqr acute WET using Dapphnia magna and Pime hales romelus~ they were consistently compliant with this ~onducted accelerated testse Thosegtests re~ulted in failure for Daphnia magna, and established a pattern oftoxicm~lee MCC had Wright Water Engineers (WWE) determine the factors(s) causingg the ppattern ojtoxicity for Daphnia magna. Sampling and analysis was erformed for metals, inorganics, semi-volatile/vo7atile organics, and the resulu did not indicate toxicz from an of~he ammeters measured. MCC completed the Preliminary Toxicity Identifcation (PTI) in November 2002, the results o~which were inconclusive, but suggested chat the toxicity was due to elevated levels in TDS, and alkalinity in particular. To further investigate the issue, split samples were collected by MCC, and sent to separate laboratories for parallel Toxicity Identification Evaluations (TIE), and additional tests to be conducted by one the labs to assess whether alkalinity could be responsible for [he toxicity. The conclusion of the study identified TDS/alkalinity as the significant factor in the mortality of Daphnia. Addirionally, Mountain Coal Company conducted an Aquatic Impairment Study (Februazy, 2003) on the North Fork of the Gunnison River to determine the impacts to this stream from Outfall 017. The finding was that the results of the study did not reveal any significant impacts resulting from this discharge. The current implementation of WET testing in permits allows (or consideration of various approaches to rovide some relief from routine WET testing when if is demonstrated the WET test failures are caused by TDS and where there are na signiffiicant impacts to the receiving water. Relief from WET testing requirements can be considered when TDS remova[from an effluent may not be cost effective. Based upon this information, the Division considers this request o{WET testing from chronic to acute using Daphnia magna, appropriate. To further attest to the presence of TDS/alkalinity, the test method for ou fall 017 will remove alkalinity as an interference; because with a high alkalinity, other causes of toxicity cannot be determined. This renewal permit continues the exemption from WET testing for Outfalls 004 and 016 when discharges consist of only surface runoff water. When surface runoff water only was discharged, such shall be noted on the appropriate DMRs. iii. Acute WET Limits: Because of demonstrated toxicity in mine water discharged by several permirtees, the Division e laves t ere is reasonable potential for the discharge io interfere with attainment of applicable water quality classi cations or standards. Therefore, an acute toxicity limit has been continued in the permit for Outfalls 004, 011, 012, 113, 016, and 017. The permittee is required to conduct quarterly monitoring consistent with the freqquency specifications in the Colorado Water uali Control Division Biomonitorin Guidance Document dated July 1, 1993, the results of which arm re orte as an a, w is is t e concentration at w is o or more of the or anums die. If the LCsa occurs in a concentration of Isess than or equal io 100% effluent, the permittee is require [o comply with the specificatiorzs identified in Part I.A. of the permit. Alkalinity will be ad usted to a level < 1,500 mpp//ll~~ which will correspond to a maximum "no effects" level based the breakpoint b(mortality for Da hnia ma a. AlCother conditions of the Acute WET test will remain consistent with the guidance. -This applies only tot is species, and not Pimephales oromelus. iv. General Information: The permittee should read the WET testing section of Part LA. of the permit carefully. The permit out Ines t e test requirements and the required follow-up actions the permittee must take 1o resolve a toxicity incident. The permittee should read, along with the documenu listed in Part LA. of the permit, the Colorado Water all Control Division Biomonitorin Guidance Document dated July 1, 1993. his document out tines t e criteria use y t e ivision in suc areas as grarsring re tie om WET testing modzlving Zest methods and changing test species. The permittee should 6e aware that some of the conditions outfzned a-bhove may be subjecl to change if the facility experiences a change in discharge, as outlined in Part ILA.2. of the permit. Such changes shall be reported to v. Outfalls 005, 007, 008, 009, 014, 01 S and 018 at the West Elk Mine facility do not receive a significant volume of toxic or industrial wastes and, in accordance with Regulation No. 61 Section 61.8(21(b)(i)(B) of the "Colorado Discharge Permit System Regulations", the discharges do not have the reasonable pofennal to cause, or measurably contribute to, an excursion above any narrative standards for water quality. Therefore, WET tesfing is not a requirement for these Outfalls. However, the Division reserves thhe right to reopen the permit to include WET testing, should facility conditions change or if new information becomes available. StarmWaler: stormwater from active or over ur en, raw material intermediate p. operations is required to ~i'e covered by a waters. This covesgge may be obtained u Discharge Permit. h'or facihaes that havf rovisions can then be included in individ pElk Mine, CDPS permit (No.. CO-003877( portion, and are set out in Part ID.2 0 Compan , LLC will be authorized to di Colorado. coal hat been in wish any e of such 1 to State er a CDIsS Industridl Wastewater Discharge Permit or a c,vr~ ~:ormwarer ial CDPS permits for discharge of rocess water, any applicable stormwater S permits. The individual permit or discharge of process water for the West is stormwater provisions that di er {tom the provirzons of the process water init. Under the terms of the combined individual permit, Mountain Coal stormwater associated xnih industrial activity into waters of the Slate of The terms and condirions of this permit, as related to stormwater discharges, include: a. Se re anon o stormwater Dischar es: All discharges covered by the stormwater portion of this permil shall be composed entire y o stormwater except as iscussed at Part LD.2.d. ofthe permit). stormwater, which mixes with process water, u subject to process wafer controls. Discharges from sources other than stormwater must be addressed by the process water controls in this CDPS permit. l.art Revisrd: 4/1920D4