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<br />Interoffice Memorandum <br /> <br />November 6, 2018 <br /> <br />From: Leigh Simmons <br />To: Zach Trujillo <br /> <br />Subject: Colowyo Mine (Permit No. C-1981-019) <br /> TR-125 <br /> <br />You requested that I review the material submitted by Tri-State Generation and Transmission <br />Association Inc. (Tri-State) on behalf of Colowyo Coal Company (CCC) with the TR-125 <br />application. <br /> <br />TR-125 seeks to address the requirements of Stipulation 7, and in the cover letter submitted with the <br />application Tri-State specifically requests that Stipulation 7 be removed from the permit. <br /> <br />Stipulation 7 was added to the permit on May 4, 2007, and reads: <br />THE COLOWYO COAL COMPANY SHALL SUBMIT A TECHNICAL REVISION TO THE DIVISION WHICH <br />PROVIDES AN ANALYSIS OF GROUNDWATER POINTS OF COMPLIANCE AT THE COLOWYO MINE <br />PURSUANT TO RULE 4.05.13(1). THIS ANALYSIS WILL BE DONE IN CONSULTATION WITH THE DIVISION <br />AND WILL INCLUDE A WRITTEN DETERMINATION OF THE NEED FOR GROUNDWATER POINTS OF <br />COMPLIANCE AT THE MINE. IF DEEMED APPROPRIATE, BASED ON THIS ANALYSIS, COLOWYO SHALL <br />ESTABLISH ONE OR MORE POINTS OF COMPLIANCE FOR THE COLOWYO MINE. <br /> <br />The materials submitted with TR-125 include several revised pages of text and two revised maps, as well <br />as a new exhibit: Exhibit 7 Item 15, which comprises a 2018 report by AECOM and a 2015 report by <br />Petersen Hydrologic. <br /> <br />My review is based on the content of proposed Exhibit 7 Item 15, which is, in turn, based on a single <br />rule: 4.05.13(1)(b). With this in mind, my memo is organized by topic rather than by rule citation. <br /> <br /> <br />Groundwater classification and standards <br /> <br />The conclusions of the AECOM report appear to be predicated on a misinterpretation of Regulation 41 - <br />THE BASIC STANDARDS FOR GROUND WATER [1]. Reg 41, which was promulgated under the Colorado <br />Water Quality Control Act, has been notoriously difficult to interpret. Following amendments to the Act <br />in 1989, with Senate Bill 181, a Memorandum of Agreement (MOA) was entered into between the <br />various concerned state agencies to clarify the responsibilities and authority of each [3]. <br />The MOA states that: <br />The WQCC [Water Quality Control Commission] is to remain solely responsible for the adoption <br />of water quality standards and classifications for state waters. Each implementing agency is to