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~OLORADO DEPARTMENT OF PUBLIC HEALTHAND ENVIRONMENT, Wier Quality Control Division Rationale -Page 7, Permit No. CO-0038776 For Outfall 017, with the changge stream standards, chronic WET would now apply. Previously, MCC was required to monitor for acute WET using Da hnia magna and Pime hales romelus they were consistently compliant with this permit requirement until the final quarter of 2002, a test ai a or ap nia magna. With this failure, the permittee conducted accelerated tests. Those tests resulted in failure for Daphnia magna, and established a pattern of toxicity. MCC had Wr~ht Water Engineers (WWE) determine the factors(s) causing the pattern of toxicity for Daphnia magna. Sampling an analysis was erfornzed for metals, inorganics, semi-volati e/vo able organics, and the results did not indicate toxicity from any of the ammeters measured. MCC completed the Preliminary Toxicity Identifcation (PTI) in November 2002, the results o~which were inconclusive, but suggested that 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 Identi~icapon Evaluations (TIE), and additional rests to be conducted by one the labs to assess whether alkalinity could be responsible for the toxicity. The conclusion of the study identified TDS/alkalinity as the significant factor in the mortality of Daphnia. Additionally, Mountain Coal Company conducted an Aquatic Impairment Study (February, 2003) on the North Fork of the Gunnison River to determine the impacts fo this stream from Outfall 0/7. The ftndmg was that the resulu 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 provide some relief from routine WET testing when it is demonstrated the WET test failures are caused by TDS and where there are no significant impacts to the receiving water. Relief from WET testing requirements can be considered when TDS removalfrom an effluent may not be cost effective. Based upon this information, the Division considers this request of WET testing from chronic to acute using Daphnia magna, appropriate. To further attest to the presence of TDS/alkalinity, the test method for outfall 017 will remove alkalinity as an interference; because wish a high alkaliniy, other causes of toxicity cannot be determined This renewal permit continues [he 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 6e noted on the appropriate DMRs. iii. Acute WET Limits: Because of demonstrated toxicity in mine water discharged by several permittees, She Division e [eves t ere is reasonable potential for the discharge to interfere with attainment of applicable water quality classi fr~ications or standards. Therefore, an acute toxicity limit has been confinued in the permit for Outfalls 004, 011 012, b13, 016, and 017. The permittee is required to conduct quarterly monitoring consistent with the freqguency spectfications in the Colorado Water Ouality Control Division Biomonitorin Guidance Document, dated July 1, 1993, the results of which arm reporte as an a, w is Is t e concentration at w is o or more of the organisms die. If the LCso occurs in a concentration of lsess than or equal to 100% effluent, the permittee is required to comply with the specifications identified in Part I A. of the permit. Alkalinity will be ad'usted to a level <.1,500 mp~/~ which will correspond to a maximum "no effects" level based the breakpoint o(mortal'ity for Da hnia ma a. Al?"other conditions of the Acute WET test will remain consistent with the guidance. This applies only to f is species, and not Pt'meohales oromelus. iv. General Lnformation: The permittee should read the WET testing section of Part LA. of the permit careful!}c The permit ou~est requirements and the required follow-up actions the permittee must take to resolve a toxicity tncident. The permittee should read, along with the documents listed in Part IA. ojthe permit, the Colorado Water uali Control Division Biomonitorin Guidance Document dated July 1, 1993. This document out fines t e criteria use y 1 e ivision in sec areas as granting re fie om WET testing modifying test methods and changing test s ecies. The,permittee should be aware that some of the conditions outftned a~-bbove may be subject to change if the facility experiences a change in discharge, as outlined in Part II.A.2. of the permit. Such changes shall be reported to v. Dutfalls 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(2)(b)(i)(B) of the "Colorado Discharge Permit System Regulations", the discharges do not have the reasonable potential to cause, or measurably contribute to, an excursion above any narrative standards or water quality. Therefore, WET testng is not a requirement for these Outfalls. However, the Division reserves t e right to reopen the permit to include WET testing, should facility conditions change or if new information becomes available. 3. Stormwater: Stormwater from active or inactive coal mining operatioti~ over ur en, raw material, intermediate products, finished products, bypro operations is required fo be covered by a Colorado Discharge Permtf Syste waters. This covesgge may be obtained under either a CDPS Industrial Wi Discharge Permit. For,facikhes that have individual CDPS permits for dis. provisions can then be Included in individual CDPS permits. The individua Elk Mme, CDPS permit (No. CO-0038776) contains stormwater provisions portion, and are set out in Part LD.2 of the permit. Under the terms I Company, LLC will be authorized to discharge stormwater associated v Colorado. hat has been contaminated by contact with any cts or waste produce located on the site of such (CDPS) yermit in order to be discharged to Stare ewater Discharge Permit or a CDPS Stormwater arge of rocess water, any applicable stormwater permit or discharge ofprocess water for the West at di er om the rovisions of the process water the tom fined individual permit, Mountain Coal h industrial activity into wafers of the State of The terms and conditions 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 permit shall be composed entire y o stormwater except as iscussed at Part LD.2.d. of the permit). Stormwater, which mixes with process wafer, is subject to process water controls. Discharges from sources other than stormwaier must be addressed by the process wafer controls in this CDPS permit. Las(Revised: 4/19/2004 ~O3 6G tl sus Vic-' C~sT rak