Dames & Moore, 1999 - USDA Forest Service

1977 An Environmental Analysis report, including three alternatives for tailings pile
rehabilitation, was completed by USFS.
1982 A Decision Notice and Finding of No Significant Impact was signed by USFS to
address the planned reclamation plans. A Preliminary Assessment (PA) was
prepared by USEPA to assess potential environmental issues at the Site.
1986
A Preliminary Assessment (PA) was completed by Ecology to assess potential
environmental issues at the Site.
1989 Pacific Northwest Laboratory (PNL) with CH2M Hill, under contract to USFS,
characterized site conditions and developed a remedial design. A contractor (Del
Hur) was selected for site work; the contractor started field work.
1990-9 1 Field work was conducted by Del Hur under the oversight of USFS. The principal
work efforts completed 'included the covering of the tailings piles with gravel,
filling in a depression near the center and removing tailings material from the
edges of tailings pile 1, regrading tailings piles 2 and 3, establishing surface water
run-on diversion and runoff ditches on the tailings piles, establishing revegetation
plots on the surfaces of the piles, plugging of decant towers in the tailings piles,
ripping of portions of the Railroad Creek substrate, and placement of rip-rap
streambank protection along Railroad Creek. PNL also installed groundwater
monitoring wells after construction was completed.
1995 The U.S. Bureau of Mines (USBM) installed additional groundwater monitoring
wells across the Site for the USFS.
1996 Dames & Moore conducted an initial site visit on the behalf of Alumet, Inc., and
completed Existing Data Evaluation and Data Needs Assessment.
2.4 PREVIOUS INVESTIGATIONS AND STUDIES
Table 2.4-1 is a summary of documented investigations and studies completed at the Site from the time of
mine closure to present. The table focuses on those studies which were disclosed to contain data potentially
of use for Site characterization. The quality of the data in terms of potential use for characterization of the
Site is also presented. As noted in Table 2.4-1, a number of the studies were conducted prior to the Site
restoration efforts completed by the USFS between 1989 and 1991; these studies are, therefore, not
considered suitable for RI characterization because they are not representative of current Site conditions. A
more detailed discussion of most of the information summarized hereafter is presented in the report prepared
by Dames & Moore in September 1996, titled Existing Data Evaluation & Data Needs Assessment, Holden
Mine Site. Chelan Counry, Washington. Section 11.0 References includes the complete list of documents
noted in Table 2.4- 1 by author and year. .
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17693-005-019Uuly 19. 1999;2:22 PM;DRAFT FINAL RI REPORT