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iii iiiiuiiniii iii 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1313 Sherman 81.. Room 215 Denver, CO 80203 Phone: 17031 A66-3567 FAx: (303) 8328106 DATE: October 30, 1992 T0: Susan MorriSOn FROM: Jim Pendleton _~ RE: Seneca II-W Mine, Haul Road G Certification (Permit C-82-057) of cow N~`' b `. ~ o. ~~~G i ~,yt .f ~ rB'!6 ~ Rov Romer Governor M¢hael e. Lonq Division Director I have reviewed the Haul Road G Construction Summery report, including the engineering certification by Mr. Thomas J. Mr. Wainwright, Colorado Registered Professional Engineer No. 28482. Attached to Mr. Wainwright's summary is a density testing report prepared by Northwest Colorado Consultants, Inc. The density summary includes individual summaries of daily visits to the Haul Road G and the Sediment Pond 005 construction sites, including brief comments regarding any substandard density tests or questionable material conditions observed by the technicians. In general, the construction summary is a clear and thorough rendition of the pertinent aspects of the construction project. I commend Mr. Wainwright on the format of the report. The daily density testing reports clearly relate instances in which verification Ccheck) proctor tests were completed to determine whether the materials encountered had varied from the materials for which the proctor standards had been determined. In these cases additional pror.tor tests we r? completed to provide appropriate standards fcr density comparison. This is the appropriate methodology, which very few previous certification reports clearly describe and document. I recommend that we laud htr. Wainwright and Northwe<.t Colorado Ccnsultants for their report format. Several comments included within the daily density reports document that substandard density results occurred or that a questionable soil property was noted by the technician. i did not find any subsequent follow up comments addressing whether the substandard area had been reworked and retested or the noted condition had been investigated to determine whether it required remedial tr?atment. I recommend that you direct Mr. Wainwright to provide any documentation that may exist regarding the following density report observations: (1) On .June 18, 1992 three tests were performed and the technician noted that "the material tested generally did not meet project specifications". The technician also noted that a sample (k3) was collected to complete an additional proctor standard test. The densities ~.+e re determined to be 88% at Station a5+00 end 89': at Station 45+20. Apparently they? was a