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final capacity of the system. However, as stated in TR -21, Climax has determined that a <br />spillway capacity of about 500 cfs with five feet of hydraulic head would provide an adequate <br />spillway to pass the PMP event while maintaining adequate operational storage capacity in the <br />TSF. The use of a 500 cfs target provides Climax with additional flexibility regarding the size of <br />the operational water pool (decant pond) on the Mayflower TSF. The tunnel section itself has <br />been designed based on constructability criteria and will have a much greater flow capacity than <br />the anticipated PMP. <br />As stated in TR -21 the nominal pumping capacity of the reclaim barge pump system is 10,000 <br />gpm with the two active -duty pumps in operation. The 30 -inch reclaim pipeline from the barge <br />pump system to Supply Canal No. 2 was designed to accommodate flows up to 12,000 gpm, <br />based on flow velocity design criteria, however, the pressure rating of the pipe could <br />accommodate higher flows. <br />The 60 -inch Supply Canal No. 2 pipeline has a flow capacity of approximately 34,000 gpm. As <br />described in TR -21, this pipeline will carry water delivered through the 30 -inch reclaim pipeline <br />to the north portal of Tenmile Tunnel, plus water diverted from Searle Gulch on an occasional <br />basis. Flows from Searle Gulch will be metered into the system through the Searle Gulch <br />diversion structure. <br />Based on our previous telephone conversations, you also requested additional information <br />regarding the closure costs for the tunnel and additional explanation regarding the coverage of <br />these costs under the current reclamation bond. This information is provided below. <br />Tunnel Closure: As described in Sections 2.1 and 2.3 of TR -21, the Mayflower Flood Bypass <br />Tunnel will daylight at Inlet Portal No. 4 at an approximate elevation of 10,820 feet which <br />coincides with the planned approximate crest elevation of 5 Dam. Inlet Portals 1 through 3 will <br />be used during operation as the emergency flood bypass inlets to the tunnel. Together with the <br />Outlet Portal below 5 Dam, Inlet Portal No. 4 is intended to provide a second point of <br />ingress /egress to the tunnel. Inlet Portals 1 through 3 will be sequentially closed as the elevation <br />of the TSF rises over time. Near the end of active TSF operations, Inlet Portal No. 3 will be <br />closed and Inlet Portal No. 4 will serve as a temporary bypass inlet until the overflow weir to the <br />surface spillway is constructed for emergency flood control. The weir will be constructed at an <br />elevation below the elevation of Inlet Portal No. 4 such that water from the Mayflower TSF can <br />never reach the portal. Inlet Portal No. 4 will then remain permanently open to provide access to <br />the tunnel when needed. The ultimate closure of the tunnel therefore will require only one <br />additional bulkhead (Mass Concrete Plug) within the main tunnel to control seepage, as <br />described in Section 2.9 of TR -21. <br />Reclamation Costs for Tunnel Closure: The approximate cost to close the Mayflower Flood <br />Bypass Tunnel at the end of operations is $530,000. There is sufficient financial assurance for <br />this cost already in place as a result of changes being made to the post - closure East Side Channel <br />and Pipeline. <br />The AM -06 site closure concept contemplates parallel systems to convey both impacted and <br />fresh water along the east side of the Robinson, Tenmile and Mayflower TSFs, roughly parallel <br />2 <br />