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iii iiiiiiiiiiiii-ii <br />Memorandum <br />To: Dan Hernandez, and Dave Berry <br />From: Janet Binns <br />Date: 08/18/00 <br />Re: Twentymile oal Company Petition to raise pH limits on NPDES Permit CO-0042161 <br />File: C:/jhb/C82056/dmr's/CO0042161 pH change <br />Twentymile Coal Company is petitioning the Colorado Department of Public Health and Environment to <br />raise the upper pH limit on CDPS permit no. CO-0042161, Outfall No. 001. TCC is requesting to raise the <br />pH limit to 10.0 s.u. 40 CFR Section 434 sets the limit at 9.0 s.u. When 1 spoke to Rick Mills about <br />meeting the 40 CFR Sec. 434 requirement of 9.0 s.u., he indicated that Empire had standards higher than 9.0 <br />pH at the Eagle 5 & 9 Mine. <br />I looked into the Eagle 5 & 9 CDPS Permit CO-0034142. In 1995 they had a pH limit at Outfall No. 023 <br />of 6.5-9.7 s.u. for "Alternate Limitations" (greater than 10 yeaz 24 hour precip. event). However, the permit <br />CDPS Issued (not dated) ,exp. 12/31/98, defines the pH limits for Outfall No. 023 as 6.5-9.0. (no newer <br />permit was on file for the Eagle 5 & 9 mine) Page 13 of the CDPS permit references applicable Federal <br />Effluent Guidelines and standards as 40 CFR 434 and states the pH limits as 6.0 s.u. and 9.0 s.u. Page 14 of <br />the CDPS permit further explains the rational of the standards and states, <br />For Outfalls 023 and 024, the previous permit had a pH limit of between 6.5 s.u. and 9.7 s.u. <br />Although a pH of 9.7 in the dischazge does not impact the instream pH of the Williams Fork River, <br />as indicated in the previous permit rationale, the petmitee must comply with the technology-based <br />standards. Therefore, a pH limitation of between 6.5 s.u. and 9.0 s.u., (6.5 based on water quality <br />and 9.0 s.u. based on federal standards), will be included in the proposed limit. <br />So, the point of this memo, after having spoken to Rick Mills regarding the Division's concern with <br />compliance with rule 4.05.2(7), and the appazent conflict raising the pH limit would have with 40 CFR 434, <br />do you want me to write a letter to Jon Kubic of CDPH&E? I have held off until I have direction from <br />either one of you. The close of the Health Departments public comment period is September 4, 2000. <br />Please let me know prior to that date what direction we propose to take. <br />Thank You <br />