Holden Mine Site Cleanup Conditions and Chronology

Orginal Holden Mine in Operation


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.

Chronology (Milestones) of the Cleanup Project 

  • 1996 and 1997, Federal (Forest Service & EPA) and State (WA-Dept. of Ecology, referred to as Ecology) agencies, 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).
  • April 11, 1998, the Agencies reached agreement with Intalco directing Intalco to perform a detailed cleanup study of the Holden Mine Site. 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
  • 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./li>
  • 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.
  • 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.
  • 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 macro-invertebrate 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
  • 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).
  • 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)
  • 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 ”.
  • 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.
  • 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”).
  • 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.
  • 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)
  • 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.

  • 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.
  •  2008 and 2009, Intalco performed additional field investigations to address data gaps that the Agencies had identified.  Based on the initial results of these investigations, Intalco revised Alternative 13, designating the new alternative as Alternative 13M.  Intalco presented the results of the additional investigations, including an evaluation of Alternative 13M and Alternative 11, the Draft Alternative 13M Evaluation Report (Intalco 2009 - PDF: 26.6 mb).
  • June 2010, the Agencies completed the Addendum to its 2007 Supplemental Feasibility Study (ASFS) (Forest Service 2010a- PDF: 30 mb) to present relevant information not included in the Draft Alternative 13M Evaluation Report, update the remedial action objectives (RAOs), describe three remedial alternatives developed after the 2007 Supplemental Feasibility Study (Alternatives 11M, 13M, and 14), and evaluate these three additional alternatives.  As part of preparing the ASFS, the Agencies developed a new alternative (Alternative 14) to address certain Alternative 13M deficiencies (related to protection of surface water and remediating soils to achieve soil cleanup standards), and also refined Alternative 11 (termed Alternative 11M) to reflect the additional date collected in 2008 and 2009.
  • Holden Mine Proposed Cleanup Plan Released to the Public for Review on June 23, 2010.
    • This Proposed Plan (Forest Service 2010c) identifies the Preferred Alternative for contaminated soils, groundwater, and surface water at the Holden Mine Site (Site).  Discussion includes the Site background, information on the nature and extent of contamination, and the rationale for the Preferred Alternative.  This Proposed Plan also summarizes the other remedial alternatives considered during the Remedial Investigation/Feasibility Study (RI/FS) process. The Forest Service and EPA are issuing this Proposed Plan as part of their public participation responsibilities under the federal Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) Section 117(a) and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR § 300.430(f)(2). 
  •    The Record of Decision, approved on January 27, 2012,  identifies the remedial action selected to clean up environmental contamination at the inactive Holden Mine. The chosen remedy is based on the Preferred Alternative in the Proposed Plan presented to the public for comment in 2010. After reviewing all the comments submitted during the comment period, the Agencies selected a remedial action with no significant changes from the Proposed Plan.


  •  To facilitate a 2-year period of major construction for the first phase of the cleanup remedy the would begin in 2013, substantial infrastructure development and early consturction was approved for the 2011 and 2012 field seasons. 


    2013 began the first season of heavy construction in the Railroad Creek Valley.