1996-05-06_HYDROLOGY - M1977378 (3)

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Attachment SP Page SP - 3 Pemit No.CO-0044768 Description of Project The purpose of this project will address the following: 1) Force the mine pool to physical equilibrium at an accelerated rate. 2) Force the mine pool towards chemical equilibrium from a basic pH and avoid acid conditions. 3) Speed up the chemical equilibrium process by minimizing the initial oxygen dependent reaction with metal sulfides. 4) Provide alkaline solution to counteract the initial lowering of pH in the pool as oxygen is consumed. The procedure for the project is to pump alkaline waters using either caustic soda or lydrat'd lim_e�supply alkalinity, into and through the hydraulic seal at the Terry Tunnel.Should the pool elevation raise higher than expected then the project will be moved to Sunnyside Basin and the alkaline injection will be pumped through an old ventilation raise above the 2200 ore pass. The mixture will flow into the ore pass and mix with waters that flow towards the Terry Tunnel and be diverted to the 2200 ore pass. The 2200 ore pass is connected to six different levels of the mine and is the major conduit for water to spread into the workings. See attached drawing. The schedule for pumping of alkaline waters is limited due to avalanche conditions in the winter at the Terry Tunnel(11,500'elevation)and the short summer runoff period in Sunnyside Basin,typically July and August,and because of limited access to the 12,000'plus site(elevation). At The Terry Tunnel the extended injection time will typically be from June until November.The pumping rate will be set between 600 and 1200 gallons per minute due to stream flows,will allow for 129 million plus gallons to be added per season. At Sunnyside Basin during high flow conditions approximately 12 million plus gallons of water can be added to the pool per season. Pumping could continue untiCphysical equilibrium is established. Annual evaluation will determine if continuation after the initial year is warranted. It will take an estimated 195 million, 4.UQAs QIm WwJW eqpilibn . Based on — -- — - water treatment experience,to rrLL �**■ 5-W 9.5 will require the addition of at,least 200 to of lime for quality of water at expected equilibrium. SGC would add additional lime or caustic soda to counteract acidity generated by thl -_ co=M&Wits-s�'ofVggen. -The p�je&L9711tacg�a.gl.�of approximately 9 0 to 10 0 in the pool The_infection pH will be periodically adjusted �� v i based on bench scale testing to achieve a target injection pH level of 12.0. _ '' , Q Work 1 1) Once the Terry Tunnel is accessible a pipe line will be strung from McCarty Creek and combined with an injection pipe to the Terry Tunnel hydraulic seal at which a one way valve will be installed.The line will be used to pump water and pH adjusting fluids through the Terry Tunnel hydraulic seal and into the orepass. 2)Pumping will be ongoing as long as there is water available and access to the Terry Tunnel is safe.The injection would be ongoing until it appears that the mine pool is reaching physical equilibrium. 3)Once the mine pool reaches equilibrium the piping will be disassembled. 4)Reclamation of the area is addressed as part of SGC's MLR Permit(M-77-378). An&sis Pumping of high pH waters with buffering capability will enhance the following aspects of the hydraulic seal project. 1)Will speed the process of achieving physical equilibrium and allow the physical system to be evaluated over a shorter time period than would occur naturally.