Dames & Moore, 1999 - USDA Forest Service
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Dames & Moore, 1999 - USDA Forest Service

Dames & Moore, 1999 - USDA Forest Service Dames & Moore, 1999 - USDA Forest Service

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native soil is of higher permeability than the tailings materials, the water is relatively confined, creating a hydrostatic head pressure in the groundwater beneath a portion of the tailings piles. The pressure likely forces some of the groundwater upward into the tailings materials during the spring months. However, as the snowmelt diminishes and groundwater flow decreases, the hydrostatic head decreases and eventually diminishes. By September, and for the remainder of the fall and winter months. the groundwater is assumed to generally flow from the tailings materials into the groundwater beneath the piles. Data loggers installed in seven of the groundwater monitoring wells in May-June 1997 will allow further confirmation of this phenomenon during the winter months. 8.2.5 Other Physical Site Features 8.2.5.1 Mine and Honeymoon Heights The underground mine features were evaluated by reviewing maps completed during and after the mining was conducted. The mine was not entered as part of the RI due to safety considerations. The review of the mine maps indicated the presence of over 56 miles of underground workings. The majority of underground workings below the 1500-level main portal were backfilled with tailings during the operation of the mine. The workings above the main portal level are reported to be open and were not backfilled. The mine includes 16 primary levels and approximately the same number of secondary levels which are connected by two shafts and a series of inclines. The lowest level in the mine, the 2500 'level, is approximately 800 feet below the Railroad Creek valley floor at the Site. The uppermost level of the mine, the 300 level, is approximately 1,400 feet above the valley floor. The majority of the mine workings were completed in the area generally beneath the 1100- to 300-level portals; the horizontal distance of the majority of the mine workings is approximately 3,000 feet. The north westernmost extent of the underground mine workings is on the 2325-level that was terminated beneath the 1500-level ventilator portal, and is approximately 800 feet below the valley floor. The south easternmost extent of the mine is on the 1500-level that was terminated approximately 13,600 feet from the 1500-level ventilator portal, and is approximately 700 to 800 feet below Copper Creek Basin. No near-surface stopes are noted to exist on the mine and geologic maps below the 1000-level portal. The transverse faults which intersect both of the 1500-level tunnels are noted to be covered with glacial till below the 1100-level mine portal. 8.2.5.2 Mill, Mine Support Area, and Waste Rock Piles The interior of the mill facility was not evaluated in depth due to safety considerations and because the USGS had completed an assessment earlier. A sample of wall insulation was collected during the RI to assess the presence or absence of asbestos-containing inaterials (ACMs); no ACMs were found. Some unprocessed ore-(less than approximately 20 cub'ic yards), as well as limited quantities of concentrate, are located in the remains of the mill building. The maintenance building is located northwest of the mill building. The initial building was constructed by Howe Sound Company and was utilized to maintain vehicles. The building was lost to a fire but was replaced in the 1970s by Holden Village for maintenance of the transport vehicles and other equipment. Petroleum hydrocarbons in the form of fuel products and lubricants are utilized in the operations. A newer \U)M~SEAI\VOLI\COMMOMWP\WPDATA\005\REPORTSWOLDEN-2W\B4.dw 8- 1 7 17693-005-019Uuly 28. 1999;10:24 AM;DRAFTFINAL RI REPORT

maintenance building, which also houses the Holden Village potable water treatment system, was constructed in 1998 to the east of the older maintenance building and to the north of the mill structure. 8.2.5.3 Winston Home Sites Underground Storage Tanks a The assessment of the underground storage tanks (USTs) in the Winston Home Sites area documented the presence of approximately 38 USTs and 2 above-ground storage tanks (ASTs). Test pit excavations completed immediately down slope of eight USTs and the Winston home sites area did not detect petroleum hydrocarbons in soil. The tanks are not regulated under State of Washington or federal UST regulations because they are less than 1,000 gallons in size and have been used for home-related fuel storage for home heating. It has been reported by individuals who were at Holden Village as volunteers during the 1960s that the majority of fuel product in most, if not all, of the tanks was removed for use in Holden Village. 8.2.5.4 Potential Borrow Source Areas The borrow source evaluation included the assessment of a rock quarry located in the eastern portion of the Railroad Creek drainage near Dan's Camp. The quarry was utilized as the source for the rip rap placed along the banks of Railroad Creek in 199 1. The rock exposed in the quarry was evaluated visually and with rock soundness testing method. The rock was determined not to be of sufficient quality to be utilized in the future as riprap. An alternative source of rip rap was investigated in a talus slope approximately one mile east of Holden village near the existing road to Lucerne. This potential source was evaluated by the USFS in 1989 as part of the tailings pile rehabilitation project. The rock was found to be of adequate quality to be used as riprap. This was supported by the findings of Dames & Moore in 1997. The source was reportedly eliminated for consideration by the USFS due to potential dangers associated with rock fall. However, it would appear feasible to remove the rock by incorporating all safety considerations in the design. A source of granular borrow material was discovered in the slope immediately southeast of tailings pile 3. Thk amount of material for future site activities, if necessary, will need to be hrther evaluated during design in order to determine if the source is of sufficient size and quality. 8.2.6 Ecological Conditions 8.2.6.1 Aquatic Biota The aquatic biota were evaluated by collecting both fish and benthic macroinvertebrates (aquatic insects) from selected reaches of Railroad Creek and control areas, or reference reaches, both in the Railroad Creek watershed and outside the watershed. Five sampling locations were selected within the segment of Railroad Creek adjacent to and downstream of the mine tailings piles. Two sampling stations were established upstream as control or reference sites for comparison to the reaches of Railroad Creek adjacent to and immediately downstream of the mine tailings piles. Three reference stations, Bridge Creek, South Fork of Agnes Creek, and Company Creek, were established in the Stehekin watershed, outside the Railroad Creek watershed, for comparison to reaches of the downstream segment (between RC-5 and RC- 10) and the mouth of Railroad Creek (RC-3). 17693-005-019Uuly 28. 199910:24 AM;DRAFT FINAL RI REPORT

maintenance building, which also houses the Holden Village potable water treatment system, was<br />

constructed in 1998 to the east of the older maintenance building and to the north of the mill structure.<br />

8.2.5.3 Winston Home Sites Underground Storage Tanks a<br />

The assessment of the underground storage tanks (USTs) in the Winston Home Sites area documented the<br />

presence of approximately 38 USTs and 2 above-ground storage tanks (ASTs). Test pit excavations<br />

completed immediately down slope of eight USTs and the Winston home sites area did not detect petroleum<br />

hydrocarbons in soil.<br />

The tanks are not regulated under State of Washington or federal UST regulations because they are less than<br />

1,000 gallons in size and have been used for home-related fuel storage for home heating. It has been<br />

reported by individuals who were at Holden Village as volunteers during the 1960s that the majority of fuel<br />

product in most, if not all, of the tanks was removed for use in Holden Village.<br />

8.2.5.4 Potential Borrow Source Areas<br />

The borrow source evaluation included the assessment of a rock quarry located in the eastern portion of the<br />

Railroad Creek drainage near Dan's Camp. The quarry was utilized as the source for the rip rap placed along<br />

the banks of Railroad Creek in 199 1. The rock exposed in the quarry was evaluated visually and with rock<br />

soundness testing method. The rock was determined not to be of sufficient quality to be utilized in the future<br />

as riprap.<br />

An alternative source of rip rap was investigated in a talus slope approximately one mile east of Holden<br />

village near the existing road to Lucerne. This potential source was evaluated by the USFS in 1989 as part<br />

of the tailings pile rehabilitation project. The rock was found to be of adequate quality to be used as riprap.<br />

This was supported by the findings of <strong>Dames</strong> & <strong>Moore</strong> in 1997. The source was reportedly eliminated for<br />

consideration by the USFS due to potential dangers associated with rock fall. However, it would appear<br />

feasible to remove the rock by incorporating all safety considerations in the design.<br />

A source of granular borrow material was discovered in the slope immediately southeast of tailings pile 3.<br />

Thk amount of material for future site activities, if necessary, will need to be hrther evaluated during design<br />

in order to determine if the source is of sufficient size and quality.<br />

8.2.6 Ecological Conditions<br />

8.2.6.1 Aquatic Biota<br />

The aquatic biota were evaluated by collecting both fish and benthic macroinvertebrates (aquatic insects)<br />

from selected reaches of Railroad Creek and control areas, or reference reaches, both in the Railroad Creek<br />

watershed and outside the watershed. Five sampling locations were selected within the segment of Railroad<br />

Creek adjacent to and downstream of the mine tailings piles. Two sampling stations were established<br />

upstream as control or reference sites for comparison to the reaches of Railroad Creek adjacent to and<br />

immediately downstream of the mine tailings piles. Three reference stations, Bridge Creek, South Fork of<br />

Agnes Creek, and Company Creek, were established in the Stehekin watershed, outside the Railroad Creek<br />

watershed, for comparison to reaches of the downstream segment (between RC-5 and RC- 10) and the mouth<br />

of Railroad Creek (RC-3).<br />

17693-005-019Uuly 28. <strong>1999</strong>10:24 AM;DRAFT FINAL RI REPORT

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