2015-10-28_HYDROLOGY - C2010089 - Laserfiche WebLink

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TRI-STATE GENERATION AND TRANSMISSION ASSOCIATION, INC. HEADQUARTERS: P.O. BOX 33695 DENVER, COLORADO 80233-0695 303-452-6111 August 4, 2015 Ms. Kelly Morgan Water Quality Control Division Colorado Department of Public Health and Environment WQCD-B2-CWE 4300 Cherry Creek Drive South Denver, Colorado 80246-1530 RE: Upset Conditions Notification of TSS at Outfall 001 New Horizon North Mine CDPS Permit Certification #COG -850062 Dear Ms. Morgan: In accordance with Colorado Discharge Permit System (CDPS) Regulation 61.8(5)(e), Tri-State Generation and Transmission Association, Inc. (Tri-State) is providing the required written Upset Conditions notification within 5 working days for the Western Fuels -Colorado, LLC New Horizon North Mine, for flows at Outfall 001 in July 2015. This facility is authorized to discharge under CDPS Certification #COG -850062. Tri-State is the parent of Western Fuels -Colorado, LLC. While we believe that the flow was not a discharge regulated by the permit and that the sample taken of this flow was not a representative sample of a regulated discharge, we are submitting this letter notification to preserve the right to the affirmative defense of upset conditions, if necessary. On July 28, 2015 at 10:54 am, Tri-State received the lab results for the sample collected on July 15th from Outfall 001. The lab reported a concentration of 111 mg/L total suspended solids (TSS) for this sample. The permit limits for TSS are 35 mg/L (30 -day average) and 70 mg/L (daily maximum), based on federal effluent limitation guidelines. Tri-State provided the required 24-hour verbal notification of Upset Conditions on July 29, 2015 at approximately 9:45AM, based on Part II.7.b of the Permit. The source of the water flow at Outfall 001was water from an irrigation pipe that transports water from the San Miguel River for crop irrigation and other uses by local farmers. The irrigation pipe has a control valve to allow release prior to the next irrigation delivery point, minimizing the potential for flooding in nearby agricultural fields. The valve is adjacent to a public road and accessible to the public (including neighboring farmers). The irrigation water release pipe from the valve is currently connected to the Pond 001 primary spillway discharge line. The mine has not had any discharges from mine activities from Pond 001 to date. The irrigation water that flows via the valve and primary spillway discharge line does not come into contact with any industrial activities conducted at the mine. Therefore, the Upset Conditions notification is based on the lack of control over the irrigation water quality (San Miguel River). Quarterly monitoring of the upstream irrigation water indicates that water quality ranges up to 200 mg/L TSS. As noted above, Tri-State also believes that the flow that was sampled was not a discharge regulated by the permit, and that the sample taken of this flow was not a representative sample of a regulated discharge. The flow from the irrigation pipe was extremely low (between a trickle and 0.5 gpm) and the valve had to be partially opened in order to collect a sample. As the sample was from AN EQUAL OPPORTUNITY/AFFIRMATIVE ACTION EMPLOYER CRAIG STATION ESCALANTE STATION NUCLA STATION P.O. BOX 1307 P.O. BOX 577 P.O. BOX 698 A Touchstone Energy Cooperative /may CRAIG, CO 81626-1307 PREWITT, NM 87045 NUCLA, CO 81424-0698 970-824-4411 505-972-5200 970-864-7316