Holden Mine Site Cleanup

Okanogan - Wenatchee National Forest

Update on Site Cleanup Activities

Summer 2009

[This update is also available as a 20-page PDF file - 430 kb]

 

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Summer 2009 – Additional field activity

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Site Conditions and Background

Howe Sound Company's Holden Mine was one of the largest copper mines in the United States during its productive life, from 1938 to 1957. The mine and mill facilities produced approximately 212 million pounds of copper, 40 million pounds of zinc, 2 million ounces of silver, and 600 thousand ounces of gold from approximately 10 million tons of ore. During the operation, about 57 miles of underground workings were excavated. About 8.5 million tons of mill tailings, which consist of the ground rock remaining after minerals with economic values were removed, were placed on National Forest System lands near Railroad Creek, covering approximately 90 acres. Another 1.5 million tons of tailings were put back into the mine. Several large piles of waste rock are located near the mine portal and at various locations. The waste rock is rock removed from the mine that was determined not to have sufficient concentration of metals to warrant processing in the mill. The total area of disturbance from mining is approximately 120 acres, and contamination extends downstream to the mouth of Railroad creek where it enters Lake Chelan. The lower portions of the mine are flooded up to the 1500 level and acidic mine drainage is currently flowing out of the 1500 level portal. The mine employed approximately 450 people during several crucial economic periods, such as the latter part of the Depression and World War II. The mine abruptly closed in 1957 when the profitability of copper mining declined.

After Howe Sound closed the mining operation, the mining interests, including the Holden townsite, were deeded to the Lutheran Bible Institute. Holden Village incorporated in 1962 for the purposes of managing the Holden townsite as a nonprofit and interdenominational retreat center, which is its status today. Holden Village is the largest retreat center in the nation operating under a special use permit from the United States Department of Agriculture - Forest Service (Forest Service).

From 1989 - 1991, the Forest Service undertook a major project (called an interim action) to stabilize the physical movement of contaminants associated with the mine tailings. This project successfully reduced erosion of tailings into Railroad Creek, essentially ended wind-blown transport of tailing dust, and was the start of several attempts to establish vegetation on top the tailings.

Although these interim actions did much to prevent the physical movement of contaminants, several potential threats to human and environmental health still existed at the site. These include:

• Risk to human health due to direct contact with the tailings, other wastes at the Site, and groundwater that exceeds federal and state drinking water standards;
• Leaching of metallic contaminants which degrade surface water quality and reduces aquatic life in Railroad Creek;
• Cementation of isolated portions of Railroad Creek's streambed, further reducing aquatic life;
• Risk to terrestrial receptors due to exposure to tailings, contaminated soils, surface water, and other wastes; and

Continuing potential for a sudden loss of tailings into Railroad Creek during a seismic or flood event.

1975 aerial photo of the Holden Mine site including
tailings, waste rock piles, and Railroad Creek.

 

Chronology (Milestones) of the Cleanup Project

During 1996 and 1997, Federal (Forest Service & EPA) and State (WA-Dept. of Ecology, referred to as Ecology) agencies, lead by the Forest Service, conducted discussions with Intalco (successor to Howe Sound Company) about performance of a study of the inactive Holden Mine under authority of the Superfund Act (CERCLA) and the State of Washington Model Toxics Control Act (MTCA).

On April 11, 1998, the Agencies reached agreement with Intalco directing Intalco to perform a detailed cleanup study of the Holden Mine Site. The agreement is known as an Administrative Order on Consent and defines the scope of the cleanup study or Remedial Investigation/Feasibility Study (RI/FS). The overall study will characterize contamination and potential injuries to natural resources at the site (Remedial Investigation) and evaluate cleanup and restoration options (Feasibility Study). The Forest Service is the lead agency directing the performance of the cleanup study by Intalco.

 

In conjunction with the cleanup study, the Forest Service, as lead Natural Resource Trustee, is also directing natural resource damage assessment (NRDA) activities at the site under CERCLA. (For more detail see the following Section on the Natural Resource Damage Assessment process at the Holden Mine Site)

 

Intalco conducted the Remedial Investigation (RI) between 1997 and 1999. The RI included the sampling and analysis of soil, surface water, groundwater, and sediments, and documentation of other Site information. Limited ecological and human health risk assessments were conducted as part of the Remedial Investigation. The Draft Final Remedial Investigation (DRI) was submitted on July 28, 1999. Dames & Moore, 1999 - PDF: 77mb

 

In October of 1999, the Forest Service, EPA and Ecology sponsored a very successful Acid Rock Drainage Workshop at the Holden Mine with participants coming from all over the US and Canada.

 

The initial phases of the Feasibility Study (FS) began in 1999, even as Intalco was still working on the Remedial Investigation.

 

As part of the Feasibility Study, Intalco re-established approximately 100 feet of the previously collapsed main tunnel into the mine and re-entered the 1500 Level Main Portal of the Holden Mine during the fall of 2000. The purpose of the mine entry was to assess conditions within the mine workings that will assist the Agencies and Intalco in evaluating various proposed remedial actions.

 

During 2001, several field activities were completed at the Mine Site that included: installation of a series of permanent groundwater monitoring wells across Railroad Creek down gradient of tailings pile #3, installation of remote-monitoring devices for bats on the 300, 1100 and 1500 levels within the Holden Mine, sediment sampling at the Lucerne Bar on Lake Chelan for use in conducting bioassays, and excavation and sampling of several test pits and borings of the tailings piles for geotechnical and geochemical purposes.

 

On February 8, 2002 , the Draft Remedial Investigation was accepted as final by the Agencies [ Forest Service, 2002 - PDF: 60kb ] . Acceptance was based on the expectation that as part of the Feasibility Study, additional information would be subsequently developed by Intalco to resolve a considerable number of comments on the Draft Remedial Investigation . Key Findings from the Remedial Investigation:

• Exceedances of groundwater and surface water quality criteria;
• Reduction in benthic macroinvertebrate and fish populations;
• Tailings pile slope stability risks from earthquake event or erosion from a major storm event;
• Soils in the maintenance yard, lagoon area, and other portions of the Site exceed MTCA cleanup levels; and
• Near shore sediments at Lucerne Bar (an area of at least 10 acres) exceed Washington State Freshwater Sediment Quality Value (FSQV) guidance for zinc

 

On June 12, 2002, the Draft Feasibility Study (DFS) was delivered to the Agencies and Trustees for review. There were 8 alternatives (7 action & 1 “no action”) with 12 sub-alternatives analyzed in the Draft Feasibility Study (DFS).

 

In February 2003, based on the Agencies input, Intalco revised the list of alternatives by replacing Alternative #6 with a new alternative and modifying Alternative #8. There were a combined total of 16 alternatives and sub-alternatives analyzed in the Draft Feasibility Study.

 

During the fall of 2003, Intalco conducted some early work related to Remedial Action Design work. This work consisted of installation of monitoring wells and geotechnical borings and completing a detailed topographic survey of the site.

 

The October 2003 flooding in North Central Washington caused damage at the Holden Mine Site that warranted immediate action to avoid further damage to the environment. Of particular concern was the damage to riprap protection along the toe of the tailings piles, as well as gully formation across tailings pile No. 1. Therefore, the Forest Service approved an Action Memorandum on November 12, 2003 for a time-critical removal action to be conducted under the existing CERCLA Administrative Order on Consent between Intalco and the Agencies. The time-critical removal action began on November 14, 2003 and was successfully completed before November 25, 2003. (See related 2003-2004 Flood Damage Story)

 

On February 19, 2004, the Draft Final Feasibility Study (DFFS) [ URS, 2004 - PDF: 111mb ] was delivered to the Agencies and Trustees for review. There were a total of 16 alternatives and sub alternatives analyzed in the Draft Final Feasibility Study, including one that was incorrectly referred to as “no action”. These are summarized below in the Section below on “Overview of Cleanup Alternatives Evaluated in the Draft Final Feasibility Study ”.

 

In 2004 additional stream bank protection and stabilization of the Railroad Creek channel at and upstream of the vehicle bridge was required to prevent further erosion of stream bank sediments that could potentially lead to release of contaminants to the environment. Furthermore, replacement of the damaged Holden Village Vehicle Bridge was urgently needed in order to provide the necessary health and safety support should an emergency situation develop within the underground mine workings of the Holden Mine. It was important to complete this work without delay due to the potential for high water during winter storm events and spring 2005 snowmelt exacerbating rerouting of Railroad Creek above the vehicle bridge. Therefore, the Forest Service approved an Action Memorandum on August 23, 2004 for a time-critical removal action under the existing CERCLA Administrative Order on Consent. This time-critical removal action began on October 4, 2004 and was successfully completed before October 25, 2004. (See related 2003-2004 Flood Damage Story)

 

During the spring and summer of 2005 following Intalco’s submittal of the Draft Final Feasibility Study, the Agencies’ concluded that none of the Alternatives 1 through 8 would meet the threshold criteria, based on information provided in the Draft Final Feasibility Study. The threshold requirements under CERCLA are protection of human health and the environment, and compliance with applicable or relevant and appropriate requirements (ARARs). MTCA has similar threshold requirements, a detailed discussion of the threshold requirements is presented in the Supplemental Feasibility Study (Forest Service 2007). The Draft Final Feasibility Study alternatives that failed to satisfy the threshold requirements for selection of a permanent remedy under CERCLA and MTCA cannot be considered as a final cleanup action for the Site. Upon this determination, the Agencies proposed that a new alternative, referred to as the Agencies Proposed Remedy (APR) be considered. The APR combined elements of some of the alternatives described in the Draft Final Feasibility Study and included a partially penetrating barrier to contain groundwater for collection and treatment.

 

On September 1, 2005, the Agencies transmitted the APR to EPA’s National Remedy Review Board [ Hart Crowser, 2005a - PDF: 71mb ]. This alternative was later designated as Alternative 10 and evaluated by the Agencies in the Supplemental Feasibility Study [ Forest Service 2007b - PDF: 46mb ]. (For a summary of this alternative see the Section below on “Overview of Cleanup Alternatives Evaluated in the SFS”).

 

On November 18, 2005, Intalco submitted an additional remedial alternative identified as Alternative 9 [ URS 2005 - PDF: 1mb ]. (For a summary of this alternative see the Section below on “Overview of Cleanup Alternatives Evaluated in the SFS”). The Agencies also developed Alternative 11 in order to eliminate deficiencies in alternative 10, and Alternative 12, which is a true “no-action” alternative as required under CERCLA. Alternatives 9, 10, 11 and 12 were evaluated in the Supplemental Feasibility Study.

 

During the spring of 2006, high water in Railroad Creek and Copper Creek resulting from rapid snow melt caused additional erosion of tailings on Tailings Piles 1 and 2, thus necessitating more erosion repairs. Therefore, the Forest Service approved an Action Memorandum on August 28, 2006 for a time-critical removal action under the existing CERCLA Administrative Order on Consent. This time-critical removal action began on September 27, 2006 and was successfully completed by October 1, 2006. (See related 2006 Flood Damage Story)

 

On September 13, 2007, the Agencies completed its review of Intalco’s Draft Final Feasibility Study, dated February 19, 2004. The Agencies’ review of the Draft Final Feasibility Study determined that none of the alternatives it contained would meet the threshold requirements for a final remedy under CERCLA or MTCA. The Agencies accepted a final Feasibility Study [ Forest Service 2007d - PDF: 300kb ] that consists of:

• the Draft Final Feasibility Study and Intalco’s Alternative 9 Description as modified and supplemented by the Agencies’ Comments on the Draft Final Feasibility Study [ Forest Service 2007a - PDF: 200kb ]
• the Agencies’ comments on Intalco’s Alternative 9 Description [ Forest Service 2007c - PDF: 100kb ]
• the Supplemental Feasibility Study [ Forest Service 2007b - PDF: 46mb].

These documents are all included in the Administrative Record for the Site.

On October 15, 2007, Intalco submitted a new remedial option, Alternative 13 (Intalco 2007 - PDF: 16.5 mb ), for consideration by the Agencies before a Proposed Plan is announced. Alternative 13 features the relocation of Railroad Creek and use of the existing creek bed to collect contaminated groundwater from the tailings piles instead of using a barrier wall and collection trench, as specified in Alternative 11 (See the Agencies 2007 Supplemental Feasibility Study for description of Alternative 11). Additional field investigations and technical evaluations were performed at the mine site during the 2008 field season to supplement data in the administrative record regarding components of Alternative 13. Final reports and evaluations resulting from the 2008 investigations are anticipated to be delivered to the Agencies before the end of July 2009. Intalco has submitted work plans for continuation of surface and ground water quality monitoring, installation of new groundwater sampling wells, test pits/trenches on the tailings piles, pilot testing of the water treatment system, and rock source investigations during the 2009 field season.

 

The Natural Resource Damage Assessment Process at the Holden Mine Site

CERCLA provides a process for determining the degree of injury to natural resources due to the release of hazardous substances. Under CERCLA, the injured natural resources must be restored, and/or the public (represented by Trustees) may be compensated for loss of the injured resources. On February 15, 2002, Intalco delivered a Draft Injury Determination Report to the Trustees for review. The natural resource trustees for the Holden Mine Site consist of:

• USDA-Forest Service (lead trustee),
• State of Washington,
• USDOI – Fish and Wildlife Service, and the
• Yakama Nation.

In the Administrative Order on Consent for the Holden site, it was intended that the Natural Resource Damage Assessment (NRDA) process follow a parallel track to the Remedial Investigation/Feasibility Study (RI/FS) process, so that decisions on selection of the cleanup remedy and off-site natural resource restoration projects occur simultaneously.

• The habitat equivalency analysis (HEA) process is being used as a tool for facilitating Natural Resource Damage Assessment (NRDA) settlement discussions between the parties.

• The habitat equivalency analysis (HEA) is used to determine the amount of restoration (credit) that is required to compensate for past, current, and future (i.e. residual to any cleanup) injuries (debit).

• The habitat equivalency analysis (HEA) provides a means to evaluate whether settlement options meet the Trustees’ statutory obligation to “make the public whole”

• Potentially injured Natural Resources to be addressed at the Holden Mine site include:
• Railroad Creek instream habitat
• Railroad Creek riparian habitat
• Wetlands habitat
• Upland habitat
• Lacustrine habitat of Lake Chelan
• Groundwater

The Trustees compiled a list of potential restoration projects that can be used as compensation for natural resource damages caused by the Holden Mine. The list of potential restoration projects was narrowed down to 21 potential restoration projects, which will serve as the basis for settlement discussions.

 

The Trustees used the following criteria to select potential restoration projects:

• Location near the area of injury (w/in Railroad Creek drainage preferred, followed by the north part of the Chelan Basin).
• Location on public lands (or potentially private lands acquired into public ownership as part of this process).
• Restoration of similar habitat or resources as those that were injured.
• Mitigation of perpetual release of hazardous substances.
• Projects that would improve the environment and are consistent with the Trustees regulatory responsibility but would not otherwise be funded.
• Projects that are technically feasible
• Projects that provide appropriate compensation for injured resources and services

 

By early spring of 2005, the Natural Resource Trustees completed the Holden Mine habitat equivalency analysis (HEA) and began natural resource damage (NRD) Settlement discussions with Intalco. However, these Settlement discussions were suspended until after release of the Remedial Action ROD.

 

Elements Common to Most of the Alternatives Evaluated in the DFFS and SFS

The following elements are common to Alternatives 2 through 11, and some of them were included in Alternative 1.

 

Institutional Controls. Institutional controls, such as proprietary controls on private property or land use restrictions, would be implemented to limit future exposures to groundwater and source materials that could impact human health and terrestrial ecological receptors and also to ensure remedy components are not compromised by human activity.

Upon the Forest Service’s request, the Bureau of Land Management (BLM) has withdrawn the area around the Holden Mine Site from mineral entry. This withdrawal includes approximately 1,265 acres of National Forest System lands from location and entry of new mining claims under the United States mining laws. A legal description of the mineral withdrawal is provided in BLM Public Land Order No. 7533 [67 FR 50894]. Institutional controls would be adopted through administrative procedures on lands under the control of the Forest Service. Documented and recorded institutional controls would also be applied to land owned by Holden Village Inc., as determined necessary for implementation of the remedy. The Agencies anticipate documentation and recording of institutional controls during remedial design and remedial action implementation. This is likely to include restrictions that would prevent disturbance of hazardous substances that are capped and left in place (e.g., in the maintenance yard), as well as any changes in land use that would impair collection and treatment of groundwater or surface water that exceeds proposed cleanup levels.

 

Mine Access and Airflow Restrictions. Gates restricting mine entry would be maintained and monitored to control access to the mine. Debris and metal precipitates would be removed and mine supports in the Main Portal will be annually inspected and maintained for safety. Air restrictions would be installed within open portals to reduce oxygen transport through the mine on the premise that this would slow the release of metals in the Main Portal drainage.

Hydraulic Bulkheads. Excluding Alternatives 1, 2a, 3a, 6a, and 12, the remaining alternatives include hydraulic bulkheads installed in the Main Portal and Ventilator Portal to control and equalize flow discharging from the Main Portal. The bulkheads also provide a means to control a surge of mine water that may be released following subsidence of the underground workings.

Consolidation and Capping Impacted Soils. Soils above proposed cleanup levels at various locations at the Site (e.g., the former mill, lagoon area, ventilator portal detention area) would be excavated and consolidated to a permanent containment area on the tailings piles under most alternatives. In the maintenance yard, soil exceeding proposed cleanup criteria would be capped with a concrete or asphalt slab.

Copper Creek and Copper Creek Diversion Modifications. Modifications to the Copper Creek channel would be performed to reduce potential future channel migrations that would erode the tailings. The Copper Creek Diversion would be placed into a lined channel or culvert from the hydroelectric plant to Railroad Creek, to avoid seepage through tailings in this area.

Tailings Actions. Alternatives 2 through 11 all include some form of improvement of the tailings pile stability and revegetation, but the degree of improvement differs as discussed for each alternative. This includes incidental closure of an existing decant tower (possible preferred seepage pathway) on TP-1.

Upgradient Water Diversion. Under most alternatives, upgradient water diversion swales or French drains would be constructed south of the tailings and waste rock piles and maintained in perpetuity to reduce the amount of clean water run-on that would otherwise contact the tailings and waste rock materials.

Construction Material Source Development. Remediation would require development of a quarry to provide a source of riprap for stream channel stabilization. Some of the alternatives would also require obtaining soil and gravel from an existing Forest Service borrow pit (Dan’s Camp) or developing a new borrow source as part of the remedy. Locations of potential quarry sites and borrow sources will be determined as part of remedial design. The volume of construction materials needed, and the extent of source development, would differ from one alternative to another.

Railroad Creek Bank Protection. Riprap for stream bank protection would be placed to mitigate potential erosion of the tailings piles and other areas where channel migration could threaten the remedy. The extent of riprap protection varies among the different alternatives.

Water Treatment Facility. Alternatives 3 though 11 include one or more facilities for treating groundwater and surface water from different parts of the Site, to reduce metals concentrations below the proposed cleanup levels. However, the areas where groundwater and surface water would be collected for treatment, as well as the location and size of the treatment facilities, vary substantially from one alternative to another. The treated water would be discharged to Railroad Creek for all alternatives that include water treatment.

Electric Power. Most of the alternatives provide for some form of water treatment at the Site. Water treatment and management of the resulting sludge will require electric power. There is no commercially available power at the Site. Holden Village generates hydroelectric power for its needs, but does not have excess capacity that could be used to run a treatment plant. While the alternatives that include water treatment all require electricity, the amount of power required varies from one alternative to another, primarily due to differences in the amount of water that would be treated and where the water is collected. While the Agencies prefer hydroelectric generation for long-term operations, the cost analyses for the comparing alternatives assumed the use of diesel fuel to power a generator at the Site. The means for generating electricity needs to be further considered during remedial design.

Monitoring. The alternatives all include some degree of surface water and groundwater monitoring to assess effectiveness of the remedy, stability of the tailings and waste rock piles, condition of stream bank riprap, and performance of other components of the remedy.

Natural Attenuation. All the alternatives rely to some degree on passive processes that are expected to reduce the magnitude of metals released over time. These processes include a) source depletion, which is not an acceptable part of a remedy under either CERCLA or MTCA; and/or b) natural attenuation, which may be an acceptable part of a remedy provided certain conditions are met. The Draft Final Feasibility Study refers to both processes jointly, and incorrectly, as “monitored natural attenuation” (MNA).

Source depletion refers to the major source of contamination at the Site: the chemical oxidation of sulfide minerals in rock within the underground mine, tailings, and waste rock. Oxidation of the sulfide minerals releases metals and produces acidic conditions that increase solubility of the metals in groundwater at the Site. Over time, as the sulfide minerals and resulting contamination enters the environment, the quantity of remaining sulfide minerals available to cause future contamination will decrease and the ongoing release of acidic drainage and metals to groundwater will diminish. However, this source depletion of sulfide minerals does nothing to mitigate the maximum potential adverse effects of metals already or continuing to be released to the environment. Like allowing a barrel of waste to leak until empty, relying on source depletion is a “no action” approach.

Natural attenuation processes “include a variety of physical, chemical, or biological processes that, under favorable conditions, act without human intervention to reduce the mass, toxicity, mobility, volume, or concentration of contaminants in soil or groundwater.” For metals at the Site, these natural attenuation processes may include dispersion, dilution, and sorption, although these processes have not been quantified in the Remedial Investigation or the Feasibility Study.

Neither CERCLA nor MTCA allow a remedy to rely on source depletion. CERCLA and MTCA allow an alternative to include natural attenuation provided certain conditions are met.

 

 

Overview of Cleanup Alternatives Evaluated in the Draft Final Feasibility Study (DFFS)

A summary description of Alternatives 1 through 8 is provided below. The Draft Final Feasibility Study provides more detailed descriptions of the alternatives. It should be noted that components of the different alternatives are not necessarily cumulative; for example, components of Alternative 3 are not automatically included in Alternative 4.

 

Alternative 1—No Action/Institutional Controls

Total Estimated Project Cost per the DFFS: $2.73 million

This alternative was intended to represent baseline conditions for comparison to other alternatives, but it does not really represent “no action”. Under this alternative, groundwater, surface water, and seeps would continue to flow into Railroad Creek and contaminated soils would remain in place. Under this alternative, institutional controls and physical access restrictions as outlined in the previous section would be implemented. Surface water and groundwater monitoring would be performed. Tailings slopes and riprap would be visually monitored annually to evaluate potential slope failure and accidental release of tailings into Railroad Creek. Within the Main Portal of the 1500 Level, debris and metal precipitates would be removed as needed and disposed of on site to reduce the potential for accidental release.

 

Alternatives 2a and 2b—Water Management

Total Estimated Project Costs per the DFFS: $17.3 to 18.8 million

Alternative 2 mainly relies upon monitored natural attenuation (MNA) for cleanup of the site. The Main Portal drainage would continue to flow into Railroad Creek. Under two possible sub-alternatives discharge from the Main Portal would either remain unchanged (Alternative 2a), or hydrostatic bulkheads would be placed on the 1500 Level to control flow rates from the underground mine (Alternative 2b).

 

Alternatives 3a and 3b—Water Management and Low Energy West Area Treatment

Total Estimated Project Costs per the DFFS: $27.1 to 28.2 million

Discharge from the Main Portal and select seeps would be collected for treatment prior to discharge to Railroad Creek. An upper barrier wall and groundwater collection system would be placed in the West Area of the site along the toe of the waste rock piles and mill building. Intercepted groundwater and seeps would be treated prior to discharge to Railroad Creek. Collected water would be treated by chemical addition, precipitation, clarification, and media filtration in unlined treatment ponds. Under Alternative 3a, flow from the Main Portal would remain unchanged, or under alternative 3b, hydrostatic bulkheads would be placed to control of flow rate from the underground mine.

 

Alternatives 4a, 4b, and 4c—Water Management and East Area Collection and Treatment (Low Energy Treatment)

Total Estimated Project Costs per the DFFS: $34.4 to 67.5 million

Alternative 4 focuses on collection and treatment of groundwater and seeps associated with the tailings piles. Alternative 4a limits collection to Tailings Piles 1 and 3, whereas Alternative 4b extends collection to include Tailings Pile 2. For both Alternatives 4a and 4b, a barrier wall is installed between collection trenches and Railroad Creek to enhance collection efficiencies and decrease losses of Railroad Creek to collection trenches. For Alternative 4c, Railroad Creek would be relocated from approximately Tailings Pile 1 to downstream of Tailings Pile 3, and the abandoned creek channel would be modified to collect seepage and groundwater. For all these Alternatives, collected groundwater and seeps would be treated prior to discharge to Railroad Creek.

 

Alternatives 5a, 5b, 5c, and 5d—Water Management and East/West Area Collection and Treatment (Low Energy Treatment)

Total Estimated Project Costs per the DFFS: $ 40.4 to 74.3 million

Alternative 5 includes remediation components as a combination of Alternatives 3b and 4. Under Alternative 5, as in Alternative 3b, an upper barrier wall and groundwater collection system would be placed along the toe of the waste rock piles and mill building. Alternative 5d includes the addition of a LWA barrier wall and groundwater collection system along Railroad Creek extending 1,300 feet upstream from the west end of Tailings Pile 1.

 

Remediation components for these four sub-alternatives include varying the extent of groundwater collection for treatment. Alternative 5a limits collection to Tailings Piles 1 and 3, whereas Alternative 5b extends collection to include Tailings Pile 2. For both Alternatives 5a and 5b, a barrier wall is installed between collection trenches and Railroad Creek to enhance collection efficiencies and decrease losses of Railroad Creek to collection trenches. For Alternatives 5c and 5D, Railroad Creek would be relocated from approximately Tailings Pile 1 to downstream of Tailings Pile 3, and the abandoned creek channel would be modified to collect seepage and groundwater.

 

For all Alternatives, collected groundwater and seeps would be treated prior to discharge to Railroad Creek. Collected water would be treated by chemical addition, precipitation, clarification, and media filtration in unlined treatment ponds.

 

Alternatives 6a and 6b—Water Management and West/East Area Collection and Treatment (Mechanical Treatment)

Total Estimated Project Costs per the DFFS: $74.5 to 77.4 million

Alternative 6 includes components of Alternatives 3 and 4c with the addition of two components. A LWA barrier wall and groundwater collection system along Railroad Creek extending upstream 3,500 linear feet from the west end of Tailings Pile 1. Unlike Alternatives 3 and 4c, collected groundwater and seeps would be treated by chemical addition with a mechanical water treatment system, which would include aeration, pumping, clarification, and other components.

 

As in Alternative 3, the Main Portal could remain unchanged (Alternative 6a) or hydrostatic bulkheads could be placed on the 1500 Level to control flow from the underground mine (Alternative 6b).

Alternative 7—Capping, Consolidation, Water Management, and West Area Treatment

Total Estimated Project Costs per the DFFS: $100 million

Alternative 7 would include water management and treatment components as outlined under Alternative 3b. Tailings Piles 1, 2, and 3 would be consolidated onto the approximate footprint of Tailings Pile 2. A low-permeability cover would be installed on the consolidated tailings pile and the tops of the main east and west waste rock piles to reduce surface water infiltration. However, Alternative 7 does not address closure of the waste rock piles in the area of the Site referred to as Honeymoon Heights. Riprap would be placed along the toe of the consolidated tailings pile to reduce the potential for contact with Railroad Creek.

 

Alternative 8—Source Control and East/West Area Treatment

Total Estimated Project Costs per the DFFS: $113 million

Alternative 8 would include those actions summarized as part of Alternative 7 with additional actions. Both main east and west waste rock piles would be relocated to the consolidated tailings pile; however Alternative 8 does not address closure of the waste rock piles in the area referred to as Honeymoon Heights. The Main Portal drainage and flow from seep SP-23 and SP-12 would be collected and treated. The Draft Final Feasibility Study says groundwater and seeps in the Upper West Area (UWA) along the former main waste rock piles and mill building would “likely not be collected” since these waste rock piles would be relocated to the consolidated tailings pile.

 

A 3,500-foot-long groundwater collection and barrier wall system would be installed along the northern toe of the consolidated tailings pile. Collected groundwater would be treated by chemical addition, precipitation, clarification, and media filtration in unlined treatment ponds.

 

 

Overview of Additional Cleanup Alternatives Evaluated in the Supplemental Feasibility Study (SFS)

Alternative 9 —

Estimated Total Project Cost (including 30 percent contingency) per Intalco: $36.3 million

Estimated Total Project Cost per the Agencies: $37.1 million

 

A summary of Alternative 9 is provided below. A more detailed description is provided in the Supplemental Feasibility Study [ Forest service 2007b - PDF: 46 mb ] and a document prepared for Intalco titled Alternative 9 Description and Focused CERCLA-MTCA Feasibility Evaluation [ URS 2005 -PDF: 1 mb ].

 

In addition to the common elements listed above under the Draft Final Feasibility Study, Alternative 9 includes the remedial components from Alternative 3b, including collection and treatment of the Main Portal drainage and Honeymoon Heights seeps SP-12 and SP-23, and installation of a groundwater barrier and collection system in the UWA to collect groundwater impacted by infiltration at the former mill building and adjacent waste rock piles.

 

Alternative 9 also includes installation of four pumped wells for groundwater extraction below TP-1 and a seep interception system to collect flow from seeps SP-1 and SP‑2. Except for the wells and seep collection noted above, Alternative 9 is the same as Alternative 3b. Alternative 9 would rely on source depletion and natural attenuation to reduce releases of metals to groundwater and surface water from the LWA, a portion of TP-1, and all of TP-2 and TP- 3. Alternative 9 would include limited regrading and revegetation of portions of the tailings piles but would not include closure in accordance with potential ARARs.

 

Alternative 10 — Formerly identified as the APR

Estimated Total Project Cost per the Agencies: $53.8 million

Estimated Total Project Cost (including 30 percent contingency) per Intalco: $70.6 million

 

A summary description of the Alternative 10 is provided below. A more detailed description of Alternative 10 is included in the Supplemental Feasibility Study (and also in the EPA NRRB Holden Mine Site Information Package where it is referred to as the APR [ Hart Crowser, 2005a - PDF: 71 mb]. As presented to the NRRB, the APR included contingent measures that are not incorporated in Alternative 10.

 

In addition to the common elements previously described, Alternative 10 includes installation of a partially penetrating groundwater barrier and collection system in the LWA along Railroad Creek from the existing Main Portal discharge point into Railroad Creek to the Copper Creek Diversion, and along both TP-1 and TP-3 adjacent to Railroad Creek. Unlike Alternatives 3 through 9 and 11, which include fully penetrating groundwater barriers (keyed into glacial till or bedrock below the surficial aquifer), Alternative 10 includes a groundwater barrier that penetrates only part of the saturated thickness of the shallow aquifer in the Railroad Creek Watershed. A detailed hydrologic analysis of the effectiveness of this partial barrier is included in Appendix F of the Supplemental Feasibility Study.

 

Alternative 10 also included collection and treatment of discrete seeps, SP-3 and SP-4, on the northern edge of TP-2. Alternative 10 would not include the collection and treatment of groundwater below TP-2 but would rely on natural attenuation pending additional monitoring to determine whether or not the remedy is protective. Although the APR included the contingency that actions such as extending groundwater collection along TP-2, or a fully penetrating cutoff might be added later based on results of monitoring, these potential contingent actions were not analyzed as part of Alternative 10. Without these contingencies, and on the basis of existing information, Alternative 10 would not satisfy all the requirements for a remedy to rely on natural attenuation. This alternative would not provide source control to the maximum extent practicable (i.e. along TP-2); and therefore cannot be shown to eliminate threats to the environment, on the basis of existing information.

 

Alternative 10 would include regrading approximately 580,000 cubic yards of tailings and 160,000 cubic yards of waste rock to improve stability of these piles, as well as closure of the main east and west waste rock piles, and the tailings piles through placement of a soil cap to support vegetation. The APR included a planned analysis during remedial design to determine whether a 1-foot-thick soil cover would be protective, or whether the waste pile covers would need to be improved to meet the presumptive closure requirements for a limited purpose landfill. However, as analyzed, Alternative 10 does not include the contingent action of improving the cover. Alternative 10 does not address closure of the waste rock piles in the area referred to as Honeymoon Heights

 

Alternative 11— Estimated Net Present Worth Total Project Cost (Agencies Estimate): $85.8 million

Alternative 11 combines some elements of Alternatives 5, 6, and 10, and includes the common elements previously described. The distinguishing features of Alternative 11 are summarized below. A detailed description of Alternative 11 is found in the Supplemental Feasibility Study [ Forest Service 2007b - PDF: 46 mb ].

 

Alternative 11 will collect and treat groundwater and surface water that exceeds proposed cleanup levels. Metal hydroxide sludge produced as a byproduct of treatment would be disposed of in a limited purpose landfill constructed on the Site in conformance with state standards. Treated water would be discharged into Railroad Creek. Alternative 11 uses a groundwater barrier extending along the LWA and the three tailings piles to contain groundwater that would otherwise enter Railroad or Copper Creeks. A continuous barrier that intercepts all the sources of groundwater that are above proposed cleanup levels is an important part of the remedy and would prevent the release of contaminated groundwater into the creeks, thereby improving surface water quality to protect aquatic life. Groundwater barriers are a proven technology for containment of groundwater that cannot readily be cleaned up, e.g., groundwater that is below waste rock and tailings piles that are left in place.

 

Alternative 11 includes regrading the tailings piles and moving the edge of the piles away from the Railroad and Copper Creeks to reduce the risk of releasing wastes into the creek from future slope failures. Alternative 11 includes removal of the Honeymoon Heights waste rock piles and impacted soils in the ventilator portal detention area, and other measures (e.g., re-vegetation of areas disturbed during remedy implementation, within Riparian Reserves) to conform with potential applicable or relevant and appropriate requirements (ARARs). Alternative 11 will also close existing tailings and waste rock piles by capping them in accordance with state landfill standards to protect human and terrestrial ecological receptors and reduce impacts to groundwater and surface water. The cap would consist of 2 feet of soil and a geomembrane (the presumptive cover prescribed by state regulations), unless analyses during remedial design indicates an alternative cover would satisfy performance standards in the regulations.

 

Alternative 11 includes institutional controls to limit future human exposure to groundwater, waste materials, and contaminated soils; and to prevent changes in Site use that could impair the effectiveness of the remedy. Alternative 11 includes removal of ferricrete from Railroad Creek. Alternative 11 also includes a terrestrial ecological risk assessment to determine the final soil cleanup requirements and the extent of soil cleanup required in the LWA and north of Railroad Creek. Results of the terrestrial ecological risk assessment may also enable modification of the proposed covers for the tailings and waste rock piles.

 

 

Alternative 12 – No Action

The National Contingency Plan (NCP) requires a “no action alternative” to be developed and considered in the analysis of the developed alternatives. The no action alternative would leave the Site untouched. Under this alternative, groundwater and surface water would continue to flow into Railroad Creek without collection and treatment, and contaminated soils would remain in place, at the Site. Releases of metals into groundwater and surface water would slowly decrease over time through source depletion and natural attenuation. Metals concentrations in the tailings are expected to decrease over time as a result of source depletion and groundwater transport. Metals concentrations in soils may decrease over time due to natural attenuation, but the effect of this on bioavailibility and protectiveness of human health and the environment has not been assessed in the Draft Remedial Investigation or Draft Final Feasibility Study. No institutional controls, treatment technology, or engineering controls would be used to prevent the release of hazardous substances under this alternative.

 

 

Criteria Used in Detailed Analysis of Alternatives
(The first two are considered “Threshold” Criteria)

• Overall protection of human health and the environment
• Compliance with applicable or relevant and appropriate requirements (ARARs)
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, or volume through treatment
• Short-term effectiveness
• Implementability
• Cost
• Two additional criteria, state acceptance and community acceptance, are then evaluated based on comments received during public comment on the Proposed Plan.

 

Remedial Action Objectives (RAOs)

The Agencies’ proposed Remedial Action Objectives, to describe the requirements that must be met by the selected Site remedy, include:

• Reduce surface water concentrations of hazardous substances to levels that are protective of aquatic life and satisfy applicable or relevant and appropriate requirements ( ARARs) in Railroad Creek and Copper Creek.
• Remove ferricrete in Railroad Creek to support aquatic life, and monitor sediment quality in Railroad Creek, Copper Creek, and at the Lucerne Bar in Lake Chelan , to determine whether any further action is needed to protect aquatic life and satisfy applicable or relevant and appropriate requirements ( ARARs).
• Contain contaminants of concern in groundwater, mine discharge, and stormwater within an on-site waste management area to prevent migration of contaminants, protect aquatic life, and satisfy applicable or relevant and appropriate requirements ( ARARs).
• Reduce exposure to hazardous substances in soils, tailings, and other wastes to protect terrestrial organisms and satisfy applicable or relevant and appropriate requirements ( ARARs). Prevent future releases of tailings and other wastes into surface water that would increase surface water and sediment concentrations of hazardous substances.
• Protect human health and satisfy applicable or relevant and appropriate requirements ( ARARs) by reducing risks of human exposure to hazardous substances through direct contact with soils, tailings, and other wastes; and through groundwater as a drinking water resource.
• Implement the remedial action in a manner that satisfies applicable or relevant and appropriate requirements ( ARARs) and protects human health and the environment, including the Holden Village residential community during and after construction.

 

Project Next Steps - Schedule

The major next steps for the Holden Mine Cleanup Project are displayed below.  Before the Proposed Cleanup Plan (Proposed Plan) can be finalized, technical evaluation of results from the 2008 field investigations will be performed.  The Proposed Plan will likely reflect a combination of remedy components from Alternatives 11 and 13.  At this time, we anticipate that the Proposed Plan will be released before the end of calendar year 2009.  Therefore, the schedule for the remaining steps are projected based on an orderly and systematic advancement of the CERCLA and MTCA processes, assuming a cooperative interaction among the parties.

• July 2009 – Final reports and evaluations of data from the 2008 field investigations.
• Fall/Winter 2009 – Proposed Cleanup Plan (Proposed Plan) released for public      review (4 public meetings: Wenatchee, Chelan, Seattle and Holden Village)
• Early 2010 – Natural Resource Damage Settlement discussions resume, possibly in conjunction with Remedial Action negotiations.
• Spring 2010 – Record of Decision (ROD) for Remedial Action
• Summer 2010 - Begin Consent Decree negotiations for the Remedial Action
• Summers 2010/11 – Remedial Design, background monitoring, and possible early actions
• Field Season (2012) – Remedial Action Construction Begins (2-3 year construction period

 

Public Participation

The Forest Service, U.S. Environmental Protection Agency, and the Washington Department of Ecology are the three government oversight agencies responsible for cooperatively directing the cleanup project at Holden.

The Agencies will welcome comments from the public on what should be done to clean up the mine site. Though there are numerous competing values and interests in this process, we hope to balance both scientific knowledge and social values in the cleanup plan when it is adopted.

We are committed to making the clean up process both accessible by and responsive to the public. Toward that goal, our public participation activities are guided by a community relations plan. We encourage questions, comments and other forms of dialogue. You may contact any of our Agencies and we will respond to you as needed.

Issuing the Proposed Cleanup Plan for the Site is the next step.  The Proposed Plan is currently undergoing development and should be released for public review and comment before the end of calendar year 2009. 

The public will have a specified period of time to submit comments on the Proposed Cleanup Plan. After evaluating these comments, the Agencies will choose the appropriate plan to clean up the Holden Mine site.

Documents related to this project can be viewed at the Okanogan-Wenatchee National Forest headquarters office in Wenatchee, Washington and the Washington Department of Ecology office in Yakima, Washington. You may call Norman Day for project details.

 

Where We Can Be Reached...

Norman Day Holden Cleanup Project Manager Okanogan - Wenatchee National Forest 215 Melody Lane Wenatchee, WA 98801 (509) 664-9304
David Einan U.S. EPA Hanford Project Office 309 Bradley Boulevard, Suite 115 Richland, WA 99352 (509) 376-3883	Valerie Bound Toxics Cleanup Program Department of Ecology 15 W. Yakima Ave, Suite 200 Yakima, WA 98902-3401 (509) 454-7838

 

 

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Okanogan and Wenatchee National Forests
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