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Q: How many sites are included in the Carson River Mercury Superfund Site (CRMS)?
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A: The CRMS is one Superfund site. It does have many source areas of contamination (currently estimated to be approximately 250). Historic Comstock mill sites represent the contamination source areas
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Q: What are the contaminants at the CRMS?
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A: The Contaminants of Concern (CoCs) at the CRMS include mercury, arsenic and lead.
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Q: Have there been documented negative health impacts directly attributed to contaminants from this site?
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Q: Is there evidence of groundwater contamination at the CRMS?
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Q: Why was the CRMS made a Superfund site?
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A: Mercury in specific areas was found to be elevated in site soils, surface water, sediment, fish and some waterfowl. Lead and arsenic were also found to be elevated in site soils and sediment.
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Q: Is the site a health risk?
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A: The EPA conducted a health risk assessment in 1994 and determined that incidental ingestion of soil particles could cause negative health impacts to small children. Also, ingestion of fish and waterfowl from the CRMS could cause negative health impacts.
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Q: I heard the EPA cleaned the site up back in the 1990's?
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A: The EPA conducted five removal actions where soil with high levels of mercury were excavated and replaced with clean soil. These actions were only taken where high levels of mercury were directly associated with residential development. No action was taken where high levels of mercury were found not associated with land in residential use.
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Q: Will the site ever get cleaned up?
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A: Since the scale of the contamination encompasses such a vast area, there are no current plans for complete site cleanup. Complete cleanup would simply cost too much and disturb too much area. However, as areas are developed and sampled for contaminants, additional areas may undergo cleanup in the future.
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Q: Where did the mercury come from? Is it in the Comstock ore?
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A: While there is a very small amount of naturally occurring mercury in the Comstock ore, the mercury that is causing the contamination issue was imported from mercury mines in California. The mercury was hauled to Nevada, and then used during the ore milling process. Some mercury escaped during the milling process and some was incorporated into the tailings left-over after the milling process.
The tailings were historically disposed of directly to the environment. Over one hundred and fifty subsequent years of erosion, seasonal runoff and flooding events have redistributed the mercury down drainages and the Carson River system all the way to the Carson Sink.
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Q: Where did the arsenic and lead come from?
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A: Arsenic and lead are contained within the Comstock ore at levels that are not typically dangerous to human health. However, once the ore goes through the milling process the arsenic and lead can become concentrated in the tailings at levels which may present a health concern.
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Q: Should I worry about living on the CRMS?
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A: No, however, extra care should be taken to limit any incidental ingestion of soil/dust particles (especially by small children). A few simple measures can greatly decrease soil ingestion rates, like washing hands and dusting and vacuuming regularly. Care should also be exercised with the amount of fish and waterfowl that are taken and eaten from the Carson River, Lake Lahontan, Indian Lakes, Big and Little Washoe Lakes and the Stillwater Wildlife Refuge. Follow NDOW guidelines. Remember that smaller fish typically have less mercury than larger fish and that eating small portions over a broader time presents less risk than eating large portions over short time periods.
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Q: Who manages the CRMS, the State of Nevada or the EPA?
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A: The EPA divided the site into two Operable Units. Operable Unit 1 (OU-1) is the upland (dry land) portion of the site, while Operable Unit 2 (OU-2) is the part of the site consisting of or covered by water. While the entire CRMS is a federally listed Superfund site, after the removal actions were completed the EPA designated the State of Nevada - Division of Environmental Protection (NDEP) as the lead agency to manage the OU-1 portion of the site and activities conducted thereon. The NDEP and EPA work under a cooperative agreement, remaining in contact with regard to the CRMS and collaborating as necessary. The OU-2 portion of the CRMS remains under direct EPA management.
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Q: What has been done on the site since EPA conducted the removal actions back in the 1990's?
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A: After the removal actions were conducted, the NDEP and the EPA developed a Long-Term Sampling and Response Plan (LTSRP) for the OU-1 portion of the site. The EPA designated NDEP as the lead agency to implement the LTSRP and the NDEP has been managing the site based on LTSRP guidance ever since.
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Q: I heard that the LTSRP has been recently updated?
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Yes it has. The LTSRP was updated to include better sampling strategies to help ensure that all property development undergoes a consistent sampling program and will not present human health risks for the intended development use.
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Q: I have heard that the EPA is doing more work at mill sites on the Comstock right now?
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The NDEP (in conjunction with the EPA) is conducting an archaeological study of mill sites on the Comstock in a further attempt to document all mill site history and locate all original source areas of contamination.
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Q: I hear that the State of Nevada and the EPA are looking to expand the size of the Superfund site or restrict activities conducted on it.
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A: No, the intent of the work being done is to shrink the size of the CRMS. Due to the incredible size of this site, no formal site boundary was developed during the investigation phase (1990's) to show exactly what the location and dimensions of the site were. The NDEP has done a lot of research and has developed a site boundary and now looks to refine that site boundary further. The NDEP only wants the site boundary to include land truly impacted by contaminants from historic mining/milling activity and specifically wants to exclude land not impacted by those activities.
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Q: Are any of the activities currently being conducted by the NDEP or EPA on the CRMS a result of the mining activities being proposed by Comstock Mining Inc.?
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Q: Why doesn't the EPA or the NDEP stop Comstock Mining Inc. from disturbing the CRMS?
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A: Comstock Mining Inc. did not create the Superfund site nor cause the historic contamination. As long as Comstock Mining Inc. operates in a responsible manner and satisfies NDEP rules, requests and guidance related to their activities while operating within the CRMS, Comstock Mining Inc. will not be deemed a PRP.
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Q: What is the State of Nevada (NDEP) requiring Comstock Mining Inc. to do with regard to the Superfund site?
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A: Comstock Mining Inc. (CMI) is working with the NDEP to prepare a Sampling and Analysis Plan (SAP) and a Standard Operating Procedures (SOP) document that will identify how CMI will sample for mercury, arsenic and lead and what action(s) will be taken should high levels of these metals be found while operating within the CRMS.
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Q: Is the historic Comstock era mine waste considered hazardous waste under the Resource Conservation and Recovery Act (RCRA)?
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Q: Will Comstock Mining Inc. stir-up contamination while operating in the CRMS?
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A: While there is some potential for that to happen, the Sampling and Analysis Plan and Standard Operating Procedures document will provide a mechanism to mitigate and minimize the disturbance of CRMS contamination and reduce potential negative health risk.
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Q: Will Comstock Mining Inc. operations on the Comstock lead to more contamination?
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A: Current mining laws and regulations will be enforced to help ensure modern mining practices protect human health and the environment.
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Q: Is NDEP and the EPA concerned about CMI's mining activities within the Superfund site?
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A: Yes. The NDEP is working with CMI to prepare plans to help ensure appropriate sampling and earth moving practices are utilized so the mining operation does not negatively impact human health and/or impact the CRMS by enlarging the site or exposing or moving historic contamination to areas where it does not currently reside.
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Q: Can CMI's operations within the CRMS in any way be a good thing?
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A: There is the possibility that some material with historic contamination may be reprocessed by CMI and result in a reduction of site contaminants in those areas. Also, if CMI conducts appropriate sampling of their area of impact, more data will be generated and more will be known about CRMS contamination and its distribution in general.
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