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TETRA TECH <br />350 Indiana Street, Suite 500 <br />Golden, Colorado 80401 <br />Tel (303) 217-5700 Fax (303) 217-5705 <br />www.tetratech.com <br />Technical Memorandum <br />To: Raymond Lazuk From: Daryl Longwell <br />Environmental Manager -Climax Mine Andrew Harley <br />Doc Richardson <br />Keith Thompson <br />Company: Climax Molybdenum Company a Date: March 22, 2016 <br />Freeport-McMoRan Company (CMC) <br />Re: Eagle Park Reservoir Chemical Loading Project#: 114-910345 <br />and Mixing Analysis <br />cc: File <br />Overview <br />A mass balance mixing model has been developed to evaluate the loading of potential chemical <br />constituents to Eagle Park Reservoir (EPR) if groundwater quality equaled proposed Numeric <br />Protection Level (NPL) values to be submitted by Climax to DRMS in a revised Water Quality <br />Monitoring Plan. The mass balance mixing model was developed using available groundwater <br />quality and calculated flux values of groundwater flow to the reservoir. The geochemical mixing <br />model was constructed using PHREEQC, version 3.0.6 (Parkhurst and Appelo, 1999). This <br />modeling platform is able to process multiple equilibrium and mixing reactions that include the <br />prediction of final chemical speciation. PHREEQC is capable of performing a variety of aqueous <br />geochemical calculations, such as speciation, saturation indices, mixing of solutions, mineral and <br />gas equilibrium, and surface complexation reactions. <br />Model Development and Inputs <br />Setting <br />The attached Figure 1 provides a map of the area that identifies the monitoring locations and <br />physical features in the vicinity of EPR, including Robinson Lake, the Climax Mine process water <br />storage facility. The Robinson Lake system is considered an Environmental Protection Facility <br />(EPF). Operation of this storage system is covered under the Robinson Lake Operating Plan, <br />approved as part of TR -18, to prevent a release of water from the reservoir which could impact <br />Eagle Park Reservoir. The Robinson Lake Seepage Pump System (also an EPF) is located in the <br />primary drainage below Robinson Lake Dam, above EPR. This system, consisting of a concrete <br />Climax Molybdenum Company Page - 1 - <br />