Dames & Moore, 1999 - USDA Forest Service

The Forest Service implemented site reclamation plans between 1989 and 1991 by covering the tailings
piles with gravel to address dust generation, regrading the surfaces of the piles to improve surface water
drainage, placement of streambank protection to reduce the risk of delivery of tailings materials into
Railroad Creek, and the partial removal of cementation in the bottom of the Railroad Creek bed. Water
flowing from the underground mine workings, or'the portal drainage, was directed around the mill area and
into Railroad Creek. A series of 52 groundwater monitoring wells were installed by the Pacific Northwest
~aboratories (PNL) and the US Bureau of Mines (USBM) in 1991 and 1995, respectively, within the
tai~in~s.~iles, as well as upgradient and downgradient of the piles.
An excavation within tailings pile 1 was used as a municipal dump and intermittent sewage disposal area by
both Howe Sound and Holden Village; the area was filled and covered with tailings andlor soil during the
1989 to 1991 site reclamation effort. Efforts to revegetate the surfaces of the tailings piles were initiated
after the reclamation effort was completed. The southern portion of tailings pile 1, which was not disturbed
during the 1989 to 1991 effort, has vegetation which dates back to studies completed in the 1960s.
Approximately 50 to 60 full-time staff currently reside in Holden Village. The village receives as many as
400 visitors daily during the summer months. The village uses the maintenance yard, initially established
by Howe Sound near the mill building, for operation and maintenance of equipment. A hydroelectric plant
is located north of the mill building and utilizes water from a diversion of Copper Creek above the site.
Potable water is also provided by a diversion of Copper Creek above the Site. The Glacier Peak Wilderness
boundary is about one mile west of the village.
REMEDIAL INVESTIGATION METHODOLOGIES
The scope of work completed during the Phase I through III RI is described in the Draft Work Plan and
Sampling and Analysis Plans, and included:
• Review of historical data, including the results of studies completed from the 1960s through
1996
• Sampling and analysis of surface water, groundwater, seeps, soil, and tailings which were
performed during four sampling events in April, MayIJune, July, and September, 1997
• A geophysical survey, including both seismic refraction and electromagnetic (EM) methods
• An assessment of seismic (liquefaction), mass wasting, and erosion potential in terms of the
tailings piles
• Ecological surveys to assess the presence or absence and types of terrestrial and aquatic
wildlife
• An investigation of the mine-related above-ground and underground features
• An evaiuation to identify possible sources of rip rap and granular soil
• An inventory of underground storage tanks in the Winston Home Sites area and
excavations to assess the presence or absence of petroleum hydrocarbon fuel products in
soil
• Sampling of sediment near the mouth of Railroad Creek in Lake Chelan
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11693-005-019Uuly 28.1999;12:16 PM;DRAFT FINAL RI REPORT ES-3