Site Location and Discovery
The Coeur d'Alene Basin cleanup is known as the Bunker Hill Mining and Metallurgical Complex Superfund site. It is located in Northern Idaho and Eastern Washington. It Is one of the largest historical mining districts in the world and is approximately 1,500 square miles and 166 river miles. Mining operations began in 1883 and are continuing today. The property was known to have lead, Zinc and Silver making it a popular area for mining to take place. The mining facility disposes of tailings which end up in the rivers and streams. The mining facility due to the lack of proper disposal of waste, led to contamination throughout the flood plain of the South Fork Coeur d'Alene River, contaminants also come from large waste piles, waste rock and past air emissions from smelter operations. After tailings were released into the rivers and floodplains the nearby soil, sediment, groundwater and surface water became contaminated with heavy metals such as lead. This mining operation began in 1885 and ran for 95 years. The site only had a few workers, once the site was known to have a lot of Zinc, Lead and Silver the company employed more workers. From 1902-1912 the company employed 7,000 workers with about 460 men working in the mine in 1912. The site was a lead metal mine with silver and zinc produced as a by-product. It produced over 42M tons yielding more than 165M ounces of silver, 3.6M tons of lead and 1.4M tons of zinc. The Bunker Hill mine closed in 1991 but other operations continue to happen today in the surrounding area.
Preliminary Assessment/ Site Investigation
This site was addressed using several stages: Initial actions and three long terms of remedial phases focusing on cleanup. Initial actions included visiting the site and checking the mines surrounding areas, they had partners from the Idaho Department of Environmental Quality, Basin Environmental Improvement project Commission, Panhandle health district, other cleanup properties, mine and mill sites, where people recreate and where metals pose a environmental and health risk. They took samples from groundwater, sediment, surface water and soil to check the lead content and make a plan for the health of the people.
Contaminants
Some of the Contaminants found on site included:
- Lead
- Zinc
- Silver
- Cadmium
- Arsenic
- Manganese
NPL Ranking and Listing
The Bunker Hill Mining Site was placed on the NPL list by the Department of Environmental Protection Agency (EPA) on September 8th, 1983 with a site score of 54.76
Remedial Investigation/ Feasibility Study
The initial Site assessment was completed on August 13th, 1982. It was proposed on the NPL list on December 30th, 1982 and finalized on the NPL list September 8th, 1983. The remedial investigation began on January 2nd, 1985 and the remedy selected was completed on August 30th, 1991. Remedial action started January 31st, 1994 and construction has not yet been completed. This site has not been deleted off of the NPL list by the EPA and the most 5 year recent plan was updated on September 30th, 2021. This site is not able to return back to normal operations due to contamination still being at a high and present. During cleanup activities the superfund sites are usually broken up into multiple distinct areas called operable units. Bunker Hill was broken up into three operable units.
OU2 completed three remedial investigation and feasibility studies on
- OU1- Populated areas of the Bunker Hill box
- OU2- Non populated areas of the Bunker Hill box
- OU3- Includes areas mining related contamination outside of the Bunker Hill box in broader river basin, includes mining contaminated areas in the Coeur d'Alene River corridor, Adjacent floodplains, downstream water bodies, tributaries and fill areas.
OU2 completed three remedial investigation and feasibility studies on
- September 24th, 1985-May 13th, 1987 (EPA performed)
- May 13th, 1987-September 22, 1992 (PRP performed, EPA over sited)
- July 31, 1998-December 10, 2001 (EPA performed)
Record Of Decision (ROD)
The site consist of three operable units, so there are three records of decisions for each operable unit. Theres also a fifth year review attached of all operable units as well as a residential soil record of decision.
- Operable Unit One was published in September of 1992
- Operable Unit Two was published in October 2005
- Operable Unit Three was published in September of 2002
Remedial Design and Action
Remedy Selection
Operable Unit 1: The Primary goal of OU1 is to reduce children's intake of lead from soil and dust sources. The 1991 OU 1 ROD, 1992 OU 2 ROD and the 2012 Upper ROD Basin Amendment used remedy and remedial action objectives. The major Components of this response is:
Operable Unit 2: The following are the major components of the Selected Remedy within the Bunker Hill Box (OU 1 and OU 2) identified in the 2012 ROD Amendment
Operable Unit 3: OU 3 consists of the mining-contaminated areas in the Coeur d’Alene Basin outside of OU 1 and OU 2, primarily the following
This response will identify where the contamination has spread and what transects need to be looked into further. This will give the surveyors a good boundary on where to start immediate remedial processes and cleanup.
- Less than 5 percent of children with blood lead levels of 10 micrograms per deciliter (μg/dL) or greater
- Less than 1 percent of children with blood lead levels of 15 μg/dL or greater.
- Including localized drainage improvement actions that will protect those portions of the existing remedy that are in areas at risk from localized tributary flooding and heavy precipitation.
Operable Unit 2: The following are the major components of the Selected Remedy within the Bunker Hill Box (OU 1 and OU 2) identified in the 2012 ROD Amendment
- Actions to reduce the flow of contaminated groundwater entering the SFCDR and Government Creek
- Conveyance of effluent from the CTP in Kellogg (i.e., clean, treated water) directly to the SFCDR in a pipeline to prevent recontamination through contact with contaminated subsurface Box soil
- Groundwater collection and treatment and water management actions to reduce the flow of contaminated discharges near the Reed and Russell Adits
- CTP expansion and upgrade to treat collected water from OU 2, consistently achieve discharge requirements, allow for operation in high-density sludge mode, and reduce the volume of waste sludge generated
- Continued implementation of the ICP to protect human health
Operable Unit 3: OU 3 consists of the mining-contaminated areas in the Coeur d’Alene Basin outside of OU 1 and OU 2, primarily the following
- The floodplain and river corridor of the Coeur d’Alene River (including Coeur d’Alene Lake) and the Spokane River
- Those areas where mine wastes have come to be located because of their use for road building or for fill and construction of residential or commercial properties.
This response will identify where the contamination has spread and what transects need to be looked into further. This will give the surveyors a good boundary on where to start immediate remedial processes and cleanup.
Current Site Status
This site is no longer operable and has been closed since 1991. Remedial action is to be completed on site as of September-November of 2023.