2001-03-15_REVISION - M1977378 (3)

Home Browse Search

JOHN F. ABEL, JR. MINING ENGINEER Mr. Larry Perino Sunnyside Gold Corp. P.O. Box 177 Silverton, CO 81433 Dear Larry: 310 LOOKOUT VIEW COURT GOLDEN, CO 80401 303- 279 -4901 FAX 278 -8183 JFAbe12OHome com October 1, 2000 Rec MAR 1 2 2041 — *Ivo,ra M Fie/ of d pry• mere), ice This is the letter report you requested concerning my Geo /ogy inspection on September 27, 2000 of the completed preparations for filling the second Terry Tunnel Bulkhead. I inspected the bulkhead for 1) the spacing and location of the bars, 2) the irregularities present on the back ribs and floor, 3) soundness of the exposed rock and cleanliness of the bulkhead form and 4) the thrust collar and water stops on the bypass pipe. The bulkhead forms and the rebar installed equal or exceed the designs detailed in my August 17, 2000 letter report. I arrived at the bulkhead location at 9:00 a.m. and entered the bulkhead for the inspection. The bulkhead will occupy a length of 7 feet 3 inches, 3 inches longer than specified. The rebar cages were constructed as designed. The #10 bars had been tied into the airside cage at the minimum 3.5 inches from the bulkhead forms. The #10 tension bars were on 6 -inch centers, as specified, with the exception on the three bars that had not been tied in order for final access, inspection and filling. These bars were hanging above the access and inspection hole, ready for installation when the concrete pour reaches that elevation. The #6 temperature and shrinkage bars were tied into the waterside cage on the specified 12 -inch spacing and, the #6 bars had been tied into the waterside cage at the minimum 3 inches from the bulkhead forms. The rebars were individually cut to fit, no splices used in either rebar cage. Removal of loose rock from the tunnel roof, walls and floor has resulted in a tapered bulkhead. The shape of the rock adjacent to the bulkhead is optimal for resisting movement under the design hydraulic thrust. The irregularities present in the roof, ribs and floor are, by themselves, more than adequate to prevent the bulkhead from being forced down the Terry Tunnel. In fact, The rock irregularities will tighten the bulkhead concrete against the adjacent latite rock when the fluid pressure is applied.