Dames & Moore, 1999 - USDA Forest Service

The test pits were excavated utilizing a track-mounted backhoe. The excavations were completed to a
maximum depth of 19 feet bgs. The test pits allowed for the sampling of the subsurface materials for
laboratory testing to assess engineering characteristics. The samples were also collected for analytical
laboratory testing to characterize the metals concentrations. The results of the analytical testing are
presented in Section 5.2.6.2.
Additional test pits (DMTP3E-4 through 6) were completed to the east of tailings pile 3 to assess the area
as a potential source of granular soil for remedial activities. Test pits (DMTPIS-1, DMTP2S-I and
DMTP3S-1) were completed to the south of each tailings pile to assess the presence or absence of glacial
till soils. The results of the borrow source evaluation are presented in Section 4.2.8.
One test pit (DMTP1 E-1) was completed near the toe of the northeast comer of tailings pile 1, west of the
confluence of Railroad Creek and Copper Creek, to assess ferricrete formation in Railroad Creek. Three
additional test pits (DMP3E-1 through -3) were completed near the toe of the northeast comer of tailings
pile 3 also to assess ferricrete formation. The results of the ferricrete assessment are presented in Section
4.3.9.
Winston Home Sites
Seven test pit excavations (DMTPW-I through -7) were completed by a track-mounted backhoe in the
Winston home sites area. The purpose of the test pits was to assess the presence or absence of petroleum
hydrocarboris associated with the underground storage tanks (USTs) inventoried as part of the RI, and
discussed in Section 4.1.2.6. One test pit was located immediately downgradient of each of the seven
tanks identified at the downslope extent of the Winston home sites area (Figures 3.1 -2 and 3.1-5). Due to
the Winston home sites area being part of the Holden Mine Historic District (USFS, 1991), the test pits
were excavated immediately outside the mapped boundary.
Test pits were not completed cross gradient to the area as the east and west boundaries of the Winston
home sites Historic Area are not clearly defined. The characteristics of the subsurface soils were
documented, as well as the presence or absence of petroleum hydrocarbons based on visual and olfactory
indications. The program included the sampling of soil in the event that indications of petroleum
hydrocarbons were observed; however, no indications of petroleum hydrocarbons were noted and,
therefore, no laboratory analyses were conducted. A discussion of the geologic conditions is presented in
Section 4.2.3.
3.1.4 Borrow Source Evaluation
A borrow source evaluation was conducted with the objective of identifying possible and likely sources of
rock "riprap" (rock used for streambank erosion protection) and granular soil within the Site vicinity.
Referring to Figure 3.1-6, the study area was limited to those portions of the Railroad Creek watershed
outside the Glacier Peak Wilderness and Holden Village areas which were considered to be a reasonable
distance from the existing roads, and not constrained by physiographic features such as Railroad Creek
and steep slopes. Site visits to the areas identified during a literature and aerial photograph review were
completed to map and sample the outcrops of rock and/or deposits. Materials currently on the Site were
evaluated for potential use as a borrow source in addition to materials in other areas of the Railroad Creek
drainage. The mapping focused on the rock type, competency, fracturing and weathering characteristics,
and potential quantities of overburden and material. The relative character of.the rock was determined
G:\wpd.la\O05hponlUlaldcn-2\riU-O.doc 3-5 DAMES & MOORE
17693-005-019Uuly 19. 1999;2:07 PM:DRAFT FINAL RI REPORT