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(Page 2) <br /> MINE ID # OR PROSPECTING ID # Mom ;-378 <br /> INSPECTION DATE 7-27-93 INSPECTOR'S INITIALS ACS <br /> OBSERVATIONS <br /> This inspection was conducted primarily in relation to TR-14, the proposal to install <br /> bulkhead seals within the underground workings of the Sunnyside Mine to eliminate discharge <br /> from the Terry Tunnel, and limit discharge from the American Tunnel to those inflows that <br /> occur outby of the Sunnyside Gold property line. To that end, the four proposed bulkhead <br /> locations within the workings were visited, as well as the location of an existing water-door <br /> that is tied into the ribs with concrete. <br /> American Tunnel Bulkhead Location <br /> The approximate location of the proposed American Tunnel bulkhead has been marked with spray <br /> paint, but the precise upstream and downstream ends of the bulkhead have not been determined. <br /> The ribs in the American tunnel are heavily coated with diesel exhaust residue. There is <br /> very little inflow in the form of seeps, etc. for a considerable distance in either direction <br /> from the proposed bulkhead. The observed hydrologic conditions in the American Tunnel <br /> corroborate the conditions detailed in the Simon Hydro-Search report submitted with TR-14, <br /> i.e. once you are approximately .5 miles inby of the portal, overburden pressure is <br /> sufficient to essentially close off the joints and fractures within the rock mass to any flow <br /> of water. Almost all flows entering the American Tunnel inby of the approximately .5 mile <br /> point are from discrete veins or shear zones with enhanced permeability. The following <br /> observations apply not only to the American Tunnel bulkhead location, but to the other three <br /> locations as well: <br /> 1. The tunnel walls at the bulkhead locations are dry. <br /> 2. The only geologic structures observed at the bulkhead locations are <br /> joints. At least three sets of very tight extension joints were observed <br /> at each location. Thorough scaling at the bulkhead locations will be <br /> necessary to remove any (observed to be few) loose rocks that have resulted <br /> from near surface intersection of the joint sets. <br /> 3. The ribs at each bulkhead location are irregular, as would be expected, <br /> and appear to easily exceed the criteria for irregularity required to cause <br /> the concrete shear strength to be the controlling shear parameter for <br /> bulkhead performance, however, it was agreed that the operator would <br /> prepare two orthogonally opposed long-sections depicting tunnel <br /> irregularity at each bulkhead site once the locations are cleaned and <br /> scaled. In addition, the bulkheads will be sited in such a way that the <br /> downstream ends will coincide with inward tapering tunnel dimensions. <br /> 4. The intermediate composition volcanic rock that occurs at all bulkhead <br /> locations is extremely competent as evidenced by a ringing sound emitted <br /> when struck with a hammer. This observation is born out by the uniaxial <br /> compression test results submitted with TR-14. <br /> I-level Water Door <br /> This location was visited because it offers an opportunity to examine a concrete structure <br /> installed within the mine over 50 years ago. The concrete water-door frame was submerged for <br /> about 25 of those years, and, obviously, was not constructed with a concrete mix with the <br /> level of sophistication of that proposed for the impounding bulkheads. The old concrete was <br /> observed to be in good condition, and could probably serve the purpose for which it was <br /> installed even today. There is some degradation of the concrete at its edges, but the seal <br /> between the concrete and the ribs is still quite good. <br /> B and F-level Brenneman-Sunnyside Connection Bulkhead Locations <br /> The operator has requested partial approval of TR-14 to permit installation of these <br /> bulkheads prior to resolution of certain obstacles to approval of the American and Terry <br /> Tunnel bulkheads. Mucking out of the floor has been initiated at the F-level site, and the <br /> same observations regarding rock competency, geologic structure, etc. mentioned previously, <br />