SEMS-RM DOCID # 100035136 APPENDIX B SULPHUR BANK MERCURY MINE OU-1 RECORD OF DECISION - RESPONSIVENESS SUMMARY November 2023 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary EPA received verbal and written comments during the formal comment period on the SBMM OU-1 Proposed Plan. Verbal comments were captured in formal transcripts during two public hearings. Written comments were provided on comment cards during public meetings or sent to EPA via email or post mail. The transcripts of verbal comments as well as all written comments have been entered into the administrative record and are accessible electronically directly from the site webpage or in hardcopy at one of the site repositories indicated on the webpage. To access the electronic administrative record or review repository locations, please visit the site website: www.epa.g o v/s u p c rfu n d/s u 1 p h u rb an k m c rc u rv In this Responsiveness Summary, EPA: • organized verbal and written comments based on the topic being addressed with verbal comments first, • paraphrased comments to make this content easier to review and to combine comments addressing the same topic, • presented public comments and EPA responses in side-by-side columns. I. National Historic Preservation Acts and Tribal Disenfranchisement (Page 3) a. EPA 2006 Cleanup Violations and Tribal Lawsuit b. Destruction of Tribal Identity, History and Artifacts, and Creation of Trauma c. Tribal Disenfranchisement d. Tribal Communications and Trust Building Moving Forward II. Tribal Resources, Dances and Ceremonies (Page 6) a. Impacts to Tribal Resources and Traditional Lifeways b. Tribal Community Involvement Moving Forward III. Human Health and Environmental Risk Monitoring, Reduction, and Communications (Page 8) a. Cleanup Human Health Risk b. Northwest Rock and Waste Piles Movement c. Soil d. Air and Climate Change e. Water Quality f. Traffic IV. Next Steps for Cleanup Decisions, Community Involvement, and Other Operable Units (Page 14) Tribal Focused Public Hearing Konocti Vista Casino and Resort 2755 Mission Rancheria Rd, Lakeport, CA 95453 Tuesday, February 28th, 2023 - 6:18 - 8:06 p.m. Whole Community Public Hearing Highlands Senior Center 3245 Bowers Ave, Clearlake, CA 95422 Wednesday, March 1st, 2023 - 6:15 - 8:05 p.m. VERBAL Public Comment Topics a. Next Steps and Cleanup Decisions b. Superfund Job Training Initiative c. Timeline and Other Operable Units b. a. 1 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary WRITTEN Public Comments I. National Historic Preservation Acts and Tribal Disenfranchisement (PAGE 18) a. EPA 2006 Cleanup Violations and Tribal Lawsuit Destruction of Tribal Identity, History and Artifacts, and Creation of Trauma b. Tribal Disenfranchisement c. Environmental Justice and Federal Indian Trust Responsibility II. Tribal and Natural Resources, Dances and Ceremonies (PAGE 21) a. Impacts to Tribal and Natural Resources and Traditional Lifeways b. Tribal Community Involvement Moving Forward III. Human Health and Environmental Risk Monitoring, Reduction, and Communications (PAGE 23) a. Cleanup Human Health Risk b. Northwest Rock and Waste Piles Movement c. Soil d. Air and Climate Change e. Water f. Traffic IV. Next Steps for Cleanup Decisions, Economics, Community Involvement, and Other Operable Units (PAGE 27) a. Next Steps and Cleanup Decisions (split into 13 specific technical comments) b. Proposed Plan Technical Issues (split into 11 specific technical comments) c. Economics and Superfund Job Training Initiative d. Timeline and Other Operable Units VERBAL PUBLIC COMMENTS I. National Historic Preservation Act and Tribal Disenfranchisement a. EPA 2006 Cleanup Violations and Tribal Lawsuit b. Destruction of Tribal Identity, History and Artifacts, and Creation of Trauma c. Tribal Disenfranchisement d. Tribal Communications and Trust Building Moving Forward e. Tribal Community Involvement Moving Forward a. EPA 2006 Cleanup Violations and Tribal Lawsuit Public Comment EPA Response Public commenters stated that during EPA's 2006 Elem Indian Colony (EIC) cleanup action, EPA: • Did not follow NHPA's Section 106. • Neglected to comply with cultural resource protection procedures. • Failed to identify potential cultural resources beneath mine waste being excavated, meaning excavation below mine waste was performed to 2-4 feet without additional monitoring for resources potentially present in that material. EPA acknowledges and appreciates the comments regarding the impact of past EPA actions at the Site. In 2006, EPA collected soil samples from across the Elem Indian Colony, and in 2007 implemented a non-time critical removal action (NTCRA) to remove identified contamination with the aim of reducing the risks posed by the Site to human health and the environment. The 2007 cleanup: • removed mine waste and highly contaminated soil (about 29,500 cubic yards), 2 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Caused more than $30 million in damages to cultural resources. • Destroyed Tribal identity, history, and artifacts, causing trauma for the EIC community. Commenters also stated that after the 2006 cleanup violations, EPA: • Claimed it was exempt from the NHPA that it could not change its approach because it did not want to set a precedent for future projects. • Did not comply with the Superfund law's requirement to evaluate monetary evaluation damages to natural or cultural resources, and the necessary compensation including the purchase or preservation of similar resources in different areas. • Ignored the EIC's lawsuit against the federal government for cultural resource impacts. • Coordinated only with an unrepresentative Tribal government that was not supportive of the lawsuit. • Did not consider the cultural resource inspection report from an archeologist hired by the Tribe that uncovered the extent of tribal- cultural resources in the affected area, including a 22,000-year-old Obsidian knife. • replaced seven homes, • cleaned up or refurbished six homes, • demolished and removed several dilapidated structures, • reconstructed 3,700 ft of roadway and sidewalks, and • reconstructed the water supply system in the area. The community's recollections and feedback will be used to inform the implementation of the remedial action described in the OU-1 Record Decision. EPA is deeply committed to ensuring transparency and, where possible, mitigation for unavoidable impacts of the selected remedy on historic properties, tribal-cultural resources and tribal lifeways. Moving forward, EPA will seek to coordinate early and often with tribal leaders and community members regarding the planned action, incorporate community voices into the planning and implementation of the remedy, and formally consult with tribes potentially affected by the planned undertaking. EPA anticipates developing a memorandum of agreement with the Advisory Council on Historic Preservation and the State Office of Historic Preservation. A Tribal Communities Action Plan was developed in spring of 2022 that presents EPA's ambitions and intent with regard to coordination with the tribal community potentially affected by the SBMM Site. This plan can be found in the Administrative Record available on the SBMM webpage or at one of the AR repository locations noted in the Proposed Plan. b. Destruction of Tribal Identity, History and Artifacts, and Creation of Trauma Public Comment EPA Response Commenters stated that the destruction of cultural resources in 2006/2007 harmed the Tribal community by: • Causing a loss of EIC history and cultural identity upon the land that ties them to their ancestors and where their creation story began. • Creating lasting negative impacts on the mental health of community members. • Preventing Tribal people from living a subsistence lifestyle. The commenters requested that EPA should: • Address the trauma and destruction of cultural resources. • Support Tribal people's physical and mental health. EPA acknowledges the comments and input. EPA places high priority on Environmental Justice (EJ) and weighed EJ issues in its selection of the remedy described in this ROD. The selected remedy is consistent with Executive Order 12898 on federal actions in that it is intended to address the disproportionately high and adverse effects of the SBMM Site on EIC community members and other nearby residents. (For more information on EPA 's Environmental Justice program, please visit: www.epa.2ov/environmentalnistice/aboiit-ej-2020) The selected remedy will further reduce the burden of contamination that the community has borne due to the SBMM Site by cleaning up most contaminants on the EIC to the naturally occurring background concentrations that would have been present in the area had the SBMM never been mined. 3 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Engage the Tribal community in cleanup planning. • Collaborate to ensure the practice of Tribal traditional lifeways is Please also see the response to comment 1(a) above. As noted, EPA intends to not disrupted by future actions. coordinate closely with all parts of the community potential affected by the selected • Respond to environmental justice concerns. remedy to minimize the impact of the remedy on community members. c. Tribal Disenfranchisement Public Comment EPA Response Commenters stated that EPA's actions caused or contributed to the disenfranchisement of EIC tribal members in the following ways: • The Department of Justice lawsuit against the Bradley Mining Company and BIA, to which the EIC was a party, was not negotiated with EIC representatives that truly represented all EIC members/re sidents. • The eventual settlement eliminated the EIC's ability to sue the federal government for any matter related to the Site and eliminated the Tribe's right to any further reimbursement for natural resource damages associated with the Site. • Through this process, EPA and BIA allowed a non-representative group of EIC members to establish a government that does not have contact with those living on the colony. • The agencies" disregard for the EIC residents" subsequent lawsuit led to the disempowerment of 79 Tribal resident still living on the land. Commenters stated that Agency actions included: • Preventing EIC residents from getting justice because it may have uncovered government corruption. • Empowering close-minded Agency staff that didn't listen to what the community wanted. Staff communicated in a nasty manner, disrespected EIC residents, and caused them to feel dehumanized and treated as ""less-than." • Exclusively communicating with the Tribal government based outside of Lake County in Santa Rosa, Sonoma County. • Not ensuring EIC residents are aware of EPA communications. • Refraining from making site information publicly available. • Holding Tribal meetings off colony only with the Tribal government. • Facilitating loss of Tribal resident's civil rights, such as the ability to vote in elections and to apply for Tribal membership. Please see response 1(a) above. EPA acknowledges and appreciates these comments. EPA is committed to a government-to-government consultation with EIC, as appropriate. Also, EPA's responsibility under the Superfund law is to involve and engage with all sectors of the potentially affected community. Since 2020 EPA has substantially increased its engagement and coordination with EIC residents and other representatives of the Lake County tribal community in part to respond to community concerns about representation in the Superfund process. As described in the 2022 Tribal Communities Action Plan, EPA is committed to maintaining open lines of communication with affected community members to ensure accessibility and transparency of information about planned actions and their basis. EPA acknowledges the EIC's recent and ancestral history in the area of the SBMM Site. As noted above, EPA will seek to coordinate early and often with both tribal leaders and community members regarding the planning and implementation of the selected remedy. EPA anticipates developing a memorandum of agreement with the Advisory Council on Historic Preservation and the State Office of Historic Preservation to ensure appropriate handling of potential impacts to historic properties and tribal-cultural resources. 4 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Burdening EIC elders and parents with the dilemma and need to inform children and future generations about the disenfranchisement process and its effect on Tribal way of life. • Withholding an understanding of the human health risks and cultural impacts for future generations from the Tribal community. Commenters noted that despite these issues, the Elem Indian Colony and its residents: • Have never been relocated, even though this meant remaining on contaminated land. • Have offered support to EPA's cleanup to facilitate progress. • Have not waived their sovereignty as individuals, family members, community leaders, or as cultural traditional practitioners. • Are committed to ensuring future generations are not affected by the contamination at the Site. • Believe the Tribe has a bright future. d. Tribal Communications and Trust Building Moving Forward Public Comment EPA Response Commenters stated that EPA must have conversations and offer reconciliation to Tribal people. Through this process EPA can build trust with the whole Tribal community and not just governments. Commenters request that, during current and future cleanup activities, EPA should: • Consult with on colony Tribal residents as indigenous Tribal members. • Increase engagement with Tribal people in Clearlake, Clearlake Oaks, and Lakeport, because they are the most directly impacted and have been blocked out of this process through Tribal politics. • Identify and mark cultural sites in and around the colony to ensure they can be protected by Tribal monitors with area specific knowledge. Their monitoring will prevent ancestral artifact from being stolen. • Facilitate more communication and awareness about cultural resource monitoring and make impact reports available for Tribal people. EPA acknowledges the input and recognizes the need to support conversations, facilitate ongoing Tribal communications, and make every possible effort to build trust and reduce the potential impacts of the remedy on tribal lifeways, such as ceremonies and dances. EPA's recent efforts towards improving engagement with the community includes: • Creating a Community Liaison position to ensure open communication between EPA and Tribal residents. • Providing agreed upon notification to the Elem residents about colony access activities, such as sampling, and clearing vegetation. • Providing for and coordinating activities with Tribal monitors to ensure their availability to oversee ground disturbing work that might affect tribal-cultural resources. • The development of the Tribal Community Involvement Action Plan to hold EPA accountable to its commitments to tribal engagement. • The initiation of a Superfund Job Training Initiative program to provide training that would help community members qualification for upcoming Site-related job opportunities. • Conducting government-to-government consultation with the Elem Indian Colony Tribal government as appropriate, including before the formal cleanup decision. 5 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Offering government-to-government consultation to other area tribes. • Meetings between senior EPA management and community members to ensure there is understanding of the community's needs into the senior levels of the agency. With regard to NHPA Section 106 protections for historic properties and tribal-cultural resources, EPA is developing a Cultural Resources Assessment Report that is being developed based on field work performed in 2023 under the oversight of community- based tribal cultural monitors. This report will be used to inform engagement with the community and tribal leaders on potential impacts of the selected remedy on resources covered by the NHPA. EPA anticipates developing a memorandum of agreement with the Advisory Council on Historic Preservation and the State Office of Historic Preservation to ensure appropriate handling of potential impacts to historic properties and tribal-cultural resources. This agreement will solidify the scope and extent of mitigation required to protect these resources and is expected to include provisions such as requirements for tribal cultural monitors, handling and storage requirements for historic and tribal-cultural resources disturbed, procedures in the event that human remains are encountered, etc. To build trust moving forward, EPA needs collaborate with all Tribal people on NHPA Section 106 processes and decisions in the following ways: • Conducting historic resource evaluations before the project starts. • Ensuring availability of soil disturbing work timelines. • Performing core sampling around waste pile perimeters. • Collaborating with the Tribal community to select the locations to bury mine waste and engineers soil covers. • Including the right professional people and resources, such as Tribal monitors, historians, archaeologists. • Evaluating roadways to effectively decide on truck pathways. II. Tribal Resources, Dances and Ceremonies a. Impacts to Tribal Resources and Traditional Lifeways b. Tribal Community Involvement Moving Forward a. Impacts to Tribal Resources and Traditional Lifeways Public Comment EPA Response As EPA prepares to move forward with the cleanup, commenters requested that the Agency: • ensure Tribal residents are safe and represented in the process, • maintain effective communication, • ensure protection of Tribal resources and traditional lifeways, • reduce invasive colony access, and • avoid taking actions on dates or in locations that would impede the tribe ability to hold ceremonies, dances, and other events of religious or cultural significance. Commenters stated that the EIC residents" traditional practices have been greatly impacted by mine contamination and EPA's slow progress towards a more comprehensive cleanup action. Concerns expressed related to tribal lifeways included: During the cleanup planning, EPA will work closely with the Tribal community to conduct Tribal resource evaluations and develop cleanup methods to address community concerns and ensure the ongoing practice of traditional lifeways. The selected remedy is intended to be fully protective of traditional tribal lifeways on the Elem Indian Colony and to be protective of limited tribal use of the mine site (restrictions based upon the need to limit use of some areas where engineered caps, etc would be vulnerable to damage from foraging, etc). In some cases, the selected remedy for OU-1 may not be able to fully address an identified risk or impact on traditional lifeways, as this remedy is not able or intended to address the impacts of the site on the other Operable Units (OU2: Clear Lake and OU4: the North Wetlands [OU3 was previously incorporated into OU1]). Vegetation samples and results contained in the existing Human Health Risk Assessment were: 6 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Acorn trees on the reservation, their arsenic levels, and if they are safe to eat. Surface water flowing off the mine and potentially contaminating trees on the reservation or near the shoreline. Whether or not EPA can revitalize access to acorns, plant new trees, or ensure soil is healthy for traditional practices in the future. The need for modeling and predictions of how the land is going to look in 200 year or 300 years from now; to create realistic expectations for future generations. Uncertainty about the safety of other traditional foods and therefore the need for EPA to perform additional testing - For example, fish, Tules, crawdads, clams, and deer. The risks related to making baskets and putting Tules in the mouth if soil/sediment contamination may be stuck to them. Traditional vegetation sampling time, locations, and results. Acknowledgement that the site affects the entire Tribal community, including from Elem to Lower Lake all the way to Big Valley and Robinson Rancheria. • Gathered from oak trees and other deep-rooted vegetation in mine waste piles. They will need to be removed as a part of the cleanup, and not be allowed to reestablish because of the potential for their roots to break through the caps. • Evaluated from trees on the colony and in the surrounding area. Results indicated a minimal impact from storm water and other site contaminants. • Used to ensure cleanup planning reduces other resource and health impacts. This includes diverting preventing the formation of contaminated stormwater by covering waste piles and designing caps to allow clean stormwater to flow into the lake. Moving forward, tribal input will be used to: • Coordinate with the Tribal Liaison for site access to reduce potential impacts on dates/locations of cultural importance. • Inform where additional sampling for traditional tribal plants is performed. This sampling will be used for EPA's evaluation of the nature and extent of contamination for other Operable Units of the Site. • Inform education regarding safe and unsafe foraging areas. • Tailor the seed mixes, and in some case seedlings, used to revegetate areas during and following the remedy to best suite the community's needs. b. Tribal Community Involvement Moving Forward Public Comment EPA Response Commenters stated that the Tribal community needs to be involved throughout the process. Regardless of what happens, there is a need for EPA to plan out the phases and schedule to ensure the tribal residents can assist and support the work. Historic communication with EPA and the BIA emphasizes the need for EPA's additional effort to efficiently move the cleanup forward. Tribal residents: • want to help and reduce impacts and concerns about past, present, and future exposures to site contaminants, and • are committed to facilitate ongoing site work, to prevent delays, and to move the cleanup forward, as smoothly as possible. Commentors requested that EPA should: • Ensure an open and consistent line of communication. • Inform all Tribal members and government officials of upcoming meetings, cleanup updates, and site activities. • Ensure all residents are aware of EPA staff and contractors present in or around the colony. See responses to the comments above, particularly 1(a) and 1(d) which address the subject of community engagement surrounding the remedial design and remedial action. As noted, EPA has made commitments to community engagement for the design and implementation of this remedy and has several initiatives underway or planned to facilitate this including: • Establishment of a Tribal Community Liaison position • Provision of technical assistance through the Technical Assistance Serving Communities (TASC) program • The establishment of a Tribal Community Involvement Action Plan • The Superfund Job Training Initiative Program - The program ensures interested tribal residents can receive job training and build necessary skills to be a part of cleanup or qualify for other environmental jobs in the area. There was already a program hosted that trained Tribal people in summer 2023. • The Thriving Communities Technical Assistance Centers Program - The program helps build capacity to access federal and local grant resources. EPA Region 9 centers are based at San Diego State University and University of Arizona. Specifically, the centers can assist with grant proposal preparation, 7 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Plan for site access by providing Tribal members with training to monitor site work and assuring the community with impact reduction communications. Encourage input and expanding optimal communication channels and coordination opportunities. Increase awareness about important ceremonies occurring each year. Plan for unpredictable following significant events, such as community deaths, and the importance of preventing site work that may interrupt their process. Implementing procedures to postpone site activities when appropriate. Tribal people will not giving up their right to walk through the mine area and use it for traditional purposes. managing federal grants, identifying funding sources, navigating grant portals, and providing capacity to engage with decision making. EPA recognizes the need to support conversations and ongoing coordination with the tribal community in particular to build trust and reduce potential impacts of the remedy on tribal lifeways, such as ceremonies and dances. Accordingly, EPA intends to: • Provide agreed upon notifications to the Elem residents about site access activities, such as sampling, and clearing vegetation. • Engage with Tribal monitors to ensure availability to oversee site work with the potential to impact tribal-cultural resources, where appropriate. • Expand communication channels with EIC residents to ensure their input continues to be incorporated into planning and processes. • Remain open to input from the community on alternative means of addressing the community's needs. • Use a range of available tools to involve residents in the cleanup (see above). III. Human Health and Environmental Risk Monitoring, Reduction, and Communications a. Cleanup Human Health Risks b. Northwest Rock Pile and Other Waste Piles" Movement c. Soil d. Air and Climate Change e. Water Quality f. Increased Traffic a. Cleanup Human Health Risks Public Comment EPA Response Commenters requested that EPA consider impacts for the Elem Indian Colony, all the area's Tribal people, other residential areas including the Oasis Mobilehome Park, Island RV Park, and the neighborhoods to the south of the mine, and the whole Clear Lake community, including from: • moving the Northwest Waste Rock pile and other waste piles, • remedy impacts on air quality and climate change, • remedy impacts on Clear Lake's water quality, and • traffic associated with the remedy. Considering the issue of site-related human health risks, commenters requested that EPA should: • address the fact that the Site presents environmental justice concerns, EPA acknowledges the input. The selected remedy in this ROD is expected to: • Address soil, air, and water-related risks to human health and the environment posed by OU-1 of the Site, including on the Elem Indian Colony, in the neighborhood off Sulphur Bank Mine Road, and on the mine site itself. • Entail covering exposed areas of mine waste and site-impacted soils with clean cover material that will prevent further direct exposure to the contaminants contained in these materials. • Enable safe use of portions of the mine site for traditional practices (such as hunting, wood collection, and other activities that occur on-foot). The 2020 Sitewide Human Health Risk Assessment, (as corrected by the 2023 HHRA Errata) included: • A Traditional Tribal Risk Scenario that considered risks specific to the practice of traditional lifeways. This scenario incorporated activities, such as gathering and 8 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • conduct a more defensible analysis of the remedy's potential impacts, and • develop a more accurate understanding of health risks posed by the site based on the community's actual use of site-impacted resources. They also requested that EPA should: • consider that Elem elders have become sick and even passed away from various illnesses that all had to do with either cancer or organ failure, and • address concerns about carcinogenic materials and health issues caused by the toxins introduced to soil and water. consuming traditional foods, weaving tule baskets, and using lake water for drinking and ceremonial purposes. • An evaluation of health risk for those residents living close to the mine site. • An evaluation historic cleanups' effectiveness and confirmation that they reduced Tribal health risks. During the design of the remedy, site-specific plans will be developed including Dust Management, Traffic Management, and Storm water Management plans that will ensure that these sources of potential risk and impact to human health and the environment are appropriately managed. These plans will be made available to the community for review and input. Further sampling is currently underway to evaluate the nature and extent of contamination within the North Wetlands Operable Unit (OU-4). This evaluation will include collection of additional samples of traditional plants and a reexamination of the risks associated with traditional tribal practices. While EPA evaluates risk to the community from Superfund-related contamination, the Agency for Toxic Substances Control (ATSDR) is the lead agency for direct measurements of the impact of contaminated sites on the health of individual community members. In 1996 ATSDR published a "Revised Site Review and Update" for Sulphur Bank Mine that incorporated data from hair, blood and urine samples collected by the California Department of Health Services. This document is in the Administrative Record for this ROD. If further evaluation of a potential cancer cluster resulting from exposure to site-related contamination is needed, the community can request further evaluation/reevaluation by ATSDR. b. Northwest Rock Pile and Other Waste Piles' Movement Public Comment EPA Response Commenters raised concerns that backfilling of the Northwest pit with mine waste could result in ground water or geothermal water becoming contaminated, creating additional environmental and human health risks. Specific public input included: • EPA's decision to move the Northwest Rock Pile to the fence line or closer to the pit and how far to move it. Other input includes: o There is a junkyard in the area that was replaced with contaminated waste during a historic cleanup, o The waste should be moved on top of another waste pile and sufficiently capped. EPA acknowledges the comments and input. Section 2.12 provides details regarding the selected remedy and the specific requirements that will be incorporated into the design and implementation of the remedy. This includes requirements related to the extent of potential consolidation, engineering of the waste caps, evaluation ofNW Pit backfill, and remedy effectiveness evaluations. For the cleanup of waste piles: • The Record of Decision clearly described the criteria used by EPA to evaluate the range of alternatives, including potential offsite disposal of mining wastes from the site. For the range of reasons indicated, this approach was not incorporated into the selected remedy except for any possible hazardous non-concrete components of the former mining operations buildings, which will be taken offsite for disposal due to 9 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary o It should be completely removed to avoid inadequate action and hiding waste, o The reason for moving it and whether it is to improve environmental habitat or stop the leaching of contamination in the surrounding area. If waste piles are moved, additional precautions should be implemented including separation of groundwater water beyond the necessary requirements. For example, if five feet of separation is required then EPA should double it to ten foot to provide additional protection. Other concerns include: o Consolidating waste piles to locations that avoid geothermal activity. o A preference towards consolidating waste to areas to the southwest where they are further from residents, o The role of "cost effectiveness" in deciding whether/where to move waste piles, o If the biggest cost is bringing in dirt, then why can more waste be taken offsite. o Removal and transport of only one waste pile offsite, but not all of them according to the high cost of 70 - 60 million, o Lack of offsite waste disposal when EPA is already bringing trucks in. If the trucks on the mine site, then waste should be placed on them and moved out. o Transport of mine waste to Nevada creating a potential problem for another community, o Past efforts to cover waste piles being ineffective and creating an ugly eye sore on the site. The area was much more beautiful when it was flat. There should be some evaluation of whether it can be cleaned up and graded to be flat, o Lack of Bradley Mining Company and BIA financial contributions to the cleanup, o Choice of the company to provide clean dirt to cover the excavated areas. o Questions of how geothermal activity would be monitored in the northwest pit their particular characteristics preventing them from being disposed of within the on-mine waste management units. EPA's plans for waste consolidation will consider the impacts/benefits across the range of criteria and the consistency of waste consolidation with the overall remedial action objectives. It is expected that waste consolidation will be planned in a manner that increases the land area available for expected future uses, including traditional tribal practices. No construction contracts for any part of the selected remedy have yet been scoped, advertised or awarded, so questions of construction firm or the details of how such a firm would handle materials cannot be addressed, but will be evaluated during remedy design and monitored during remedy implementation. c. Soil Public Comment EPA Response Commentors stated that there needs to be increased access to EPA's soil studies on the Elem Indian Colony. The Agency needs communicate the soil health risks more effectively to the on-colony residents. Specifically, the arsenic risk communication is lacking, and EPA acknowledges the comments and input. As noted in Section I above, EPA has recently expanded its community involvement activities with the EIC. 10 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary The Pre-Design and Design phases of the selected remedy will entail extensive additional sampling on the Elem Indian Colony (EIC). Specific results will be shared the resident(s) of each lot and general results will be shared with all community members. In response to the public comments on this topic, EPA will incorporate additional detail regarding soil-related risks in future outreach materials for the EIC and non- tribal residential communities near the Site. d. Air and Climate Change Public Comments EPA Response There were multiple concerns about EPA starting the northwest waste rock pile cleanup. Commenters request that EPA should: • Use multiple air and dust units and monitor the area's geothermal activity. • Ensure the Elem Indian Colony Tribal residents are safe and healthy during the clean-up, with special consideration to Tribal residents": o Increased air quality risk from mine waste movement on or near the colony, o Proximity to the mine site and the need for air quality mitigation measures that consider the high levels of contamination. o Suffering though decades of health risk not only in air, but also in the whole area due to soil, vegetation, fish, and other natural resources. o Concerns about the cleanup activities because their family members have passed away at an early age, especially from cancer. o May experience exposure to additional pollutants including excessive particulate matter 2.5 or 10. Commenters requested that EPA's air monitoring should include: • Third-party monitoring to provide assurance that mitigation measures are effective. • Installation of air monitors on colony measuring arsenic levels. • Mitigation measures that reduce dust to zero because of invisible pollutants people may be breathing in as dust settles. The dust may create other risks for people around the mine. • Post cleanup review that goes beyond the typical five-year. It is too long to confirm effective human health management. EPA acknowledges the numerous comments submitted regarding dust control and emissions. The frequency of input on this subject makes clear the extent of community concern and EPA takes that concern seriously. As noted above, a site-specific plan for the prevention and management of dust emissions will be developed during the remedial design process. Given the level of community concern, this plan will be shared with the community (via a mailing list message, fact sheet, and/or community meeting). EPA expects this Dust/Air Quality Management Plan (or similarly titled planning document) to incorporate: • Specific consideration of community concerns on this subject. • All required best practices for construction related dust control measures, such as emission monitoring, application of water/surfactants to reduce dust generation, and use of appropriate Personal Protective Equipment on site to prevent workplace exposures. • Coordination with the community about the need for additional monitoring on or nearby the Elem Indian Colony. • Maximum dust levels which operational practices are expected to be adjusted to in order to prevent excess emissions. • Discussion of the role of outside organizations/agencies (such as the California Air Resources Board) in emissions control and monitoring. In an effort to reduce the selected remedy's potential impacts on air quality, local traffic and contributions to greenhouse gas emissions, EPA is actively evaluating alternative sources of the clean cover/capping material needed for the remedy. As noted in Section 2.12 of the ROD, this includes evaluation of on-site borrow areas and reuse of clean sediments/soil that might be imported to the site across the lake by barge. The design of the remedy will also consider the potential for climate change to affect the effectiveness of the remedy. In part to address this possibility, EPA has selected the 11 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Commenters requested that air quality communication for the Tribal and surrounding communities should include: • Explanation of the mitigation measures in place. • Increased awareness about EPA activity in and around the area. • Advisement for people to stay out of the area or to stay inside to ensure added protection. • Transparency of monitoring results including sharing data before, during, and after intensive soil moving days. • Explanation of risk and the difference of technically safe because contaminant levels are below regulatory limites, and if that creates some risk that may concern the community in the long-term. Also, if contaminant levels are spiking then the community needs a complete understanding of the health impacts. Commenters requested that with Lake County's increase in extreme weather events, EPA needs to: • Consider climate change's effects on the recommended cleanup. • Incorporate alternative cleanup planning and use the best available science to determine if the cleanup will still be effective. • Ensure this remedy is implemented in a way that ensures the agency doesn't have come back in 10 years to perform additional cleanup. e. Water Quality Public Comments EPA Response Commenters stated that surface water flowing downhill from the portions of the mine site near BIA Road 120 flows under/through the waste underlying the road, becomes excessively contaminated and flows into the north wetlands. With this notion in mind, commenter's pointed out that: • EPA needs to prevent water pooling on the side of BIA 120 to prevent contaminated water from flowing north into the wetlands. • The Proposed Plan did not show further cleanup to the roadway along BIA 120, so EPA should consider that the BIA 120 cleanup did not remove all mine waste below the road. • The road section should be cleaned up at the same time as the Northwest Pit and Rock Pile's. This will ensure its contamination spreading with surface and ground water. EPA acknowledges the comments and input. EPA is coordinating very closely with the state's Central Valley Regional Water Quality Control Board (CVRWQCB) and the Department of Toxic Substances Control (DTSC) to ensure: • Appropriate storm water management and protection during the cleanup, • Compliance with all necessary regulations (Applicable or Relevant and Appropriate Requirements - ARARs) for the consolidation, capping, and disposal of Site waste as it relates to the separation from and impact on water resources. • Waste piles' elevation and slope are managed effectively and not causing unacceptable degradation of water quality issues due to issues such as ponding on waste management areas. EPA is developing a storm water management system that will be a major part of the cleanup design. The cleanup design: • Includes best management practices (BMPs) during construction. more extensive Waste Rock Dam excavation approach from within the range presented in the Proposed Plan. 12 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Prevents storm water contacting exposed mine waste areas. • Allows for the discharge of clean and compliant water from management areas offsite. • Does not include excavation of BIA 120 and the Northwest Rock Pile's overlap because it was effectively capped underneath the roadway during the 2010 cleanup. The selected remedy includes measures to control the loading of site contamination (particularly mercury) to Clear Lake via groundwater flow. During the cleanup, the contaminant levels flowing with stormwater and ground water into Clear Lake will be routinely monitored. Regarding surface water impacts to Clear Lake and fish tissue, the selected remedy is necessary to address the sources of contamination to Clear Lake. EPA is continuing to evaluate the extent of contamination in Clear Lake and what remedial alternatives might enable effective control of the risks this contamination poses to human health and the environment. This remedy is a critical first step to any future remedial action for Clear Lake. f. Traffic Public Comment EPA Response Commenters raised concerns regarding traffic-related impacts of the remedy on the community and requested that EPA consider: • Sulphur Bank Drive and Sulphur Bank Mine Road may either need to be repaired or built-out to accommodate the 20-50 trucks per-day that EPA indicates remedy implementation will require. • Evaluation of tire dust risks and mitigation practices. • Communication and effective outreach when trucks will be travelling along the roadway, and potential interruptions to the community's everyday schedule. • The potential need to pause traffic for unpredictable events and the resulting schedule interruptions. • Assurance that the cleanup management will support Tribal traditional lifeways, such as funerals and ceremonies. • The county's policy requiring sheriff escorts for the fire department, ambulance, or other emergency vehicles for access to the Elem Indian Colony. EPA expects a traffic management plan and several other site-specific planning documents will be developed during remedial design and preconstruction planning to address impacts associated with traffic, construction, and local infrastructure needs. During the design process and as site-specific plans are developed, EPA expects to continue ongoing discussions with the local community about potential impacts associated with the remedy, including those from traffic, congestion, noise, dust, emissions, safety, notification, infrastructure, accommodation of cultural events, and risk reduction. • The Proposed Plan indicated that clean stormwater will be directed around the mine waste and into the lake, but EIC residents have observed that stormwater at the site moves through contamination despite the existing storm water management system. • The site areas contaminating surface water are large and could continue to contribute to increasing human health and environmental risks. 13 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary IV. Cleanup Decisions, Community Involvement, and Other Operable Unit Next Steps a. Next Steps and Cleanup Decisions b. Evaluation of Cleanup Options and Decisions c. Superfund Job Training Initiative d. Timeline and Other Operable Units a. Next Steps and Cleanup Decisions Public Comment EPA Response: Commenters presented the following: • Notification to tribal members about the Proposed Plan public meetings, formal contact of Tribal government officials, and future communication. • For the ROD, the community should be involved in a similar engagement process as the Proposed Plan (Q&As, open houses, formal meetings) including post construction decisions and commitments. • All comments being included in the Responsiveness Summary, its availability, and inclusion in the ROD. • Whether or not there will be individual response to comments like getting a letter back explaining the review, the analysis, and what will be done moving forward. • Record of Decision's aggressive timeline for the fall of 2023 and the impact that might have on EPA incorporating comment responses into the ROD. • EPA's post cleanup timeline shown in the Proposed Plan's 40- page clean-up summary, on page 37, does not include all steps of the process. Commenters presented the following concerns about timeline and trust: • EPA should have facilitated time at the beginning of this process in the mid- '90s to talk about the cleanup's complexity when the site was first listed. • There is no trust or faith in EPA as an organization, but the community wants to stay engaged, listen, and understand what's going on. • EPA's site team needs to focus on building personal trust with community members to move the cleanup timeline forward, and to support the needs of the community. The Proposed Plan engagement notification steps included: • coordinating with Tribal nations, partner agencies, community groups and businesses, • emailing 321 contacts acquired through the 2021 Community and Tribal Forums and 2021 - 2023 monthly Tribal meetings, • paper mailing to 960 addresses within a 2-mile radius of the site, • providing event details calendars at the Redbud and Lakeport libraries and county offices, • sharing information with regional partners for social media, • speaking on a local radio show, • including event details in the site's website update and with the posting of a technical presentation on YouTube, • publishing eight public notices in two local papers, and • hosting two online Q&A sessions, two in-person open houses and two hybrid (in- person and virtual) community meetings. Tribal government engagement included: • Sending letters to the seven Tribal governments in 2021 offering representatives engagement opportunities. • Coordinating monthly with Tribal representatives and residents from 2020-2023 to support their review of site documents and comments on the Proposed Plan. • Hosting two Proposed Plan formal consultation meetings with the Elem Indian Colony tribal government. • Sending letters to the Chairpeople of seven Lake County Tribes offering information sessions on the Proposed Plan and National Historic Preservation Act consultations. All comments made during the Proposed Plan public comment period will be: • Incorporated into the Administrative Record and addressed in the Responsiveness Summary portion of the ROD. • Considered in cleanup design planning and sampling, including recent updates to the agency's more robust National Historic Preservation Act approach. 14 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Everyone involved in the cleanup needs to understand the Tribal historic significance for the site, so it is respected and an important part of the cleanup moving forward. Despite the disconnect between Tribe's and EPA there is a need for all stakeholders to come together and move the cleanup forward. Tribal people engaged are the next generation to work with EPA and will continue to coordinate with the agency. • Used to inform community updates that address input and are sent via preferred communication methods. EPA expects to provide regular email updates to the community regarding the design and implementation of the selected remedy. These updates will take the form of mailing list messages, fact sheets, virtual and in-person community meetings, and updates at external public events, such as meetings of the Blue Ribbon Committee for the Rehabilitation of Clear Lake. To sign up for the site's mailing list, please use this link: www.epa.gov/superfund/sulphurbankmercurv b. Evaluation of Cleanup Options and Decisions Public Comment EPA Response Commenters raised specific cleanup decision concerns, including: • EPA regulations predetermining the process. • Evaluation criteria for cleanup decisions. • The level of priority EPA puts on community and state input in the CERCLA process and a suggestion that these should be more heavily weighed. • Human health is not the priority. Economics is, tourism is, and the fishing industry is driving this community. • The Tribal community needs more of a voice in cleanup decisions instead of EPA dictating the plan, cost, and impact for the Tribes. In EPA's final decision, it should check-in with the Tribal community. Then move forward with the decision. In addition, the entire community needs a voice, so the commenters do not have the burden of representing all affected communities. • Reasons for limiting post cleanup Tribal access to the property to twelve hours a week for traditional practices. • Adjusting the large-scale cleanup moving forward and the need to involve the community in the adjustment decisions. Sections 2.9 and 2.10 of the ROD describe how remedial alternatives were composed and compared. Please also see comments above which address the subject of community input in the remedial process and EPA's plans for community engagement moving forward. Moving into the design and implementation for the selected remedy, EPA expects to: • Coordinate with and, when appropriate, formally consult with tribes potentially affected by the implementation of the selected remedy. • Publish publicly releasable remedy design and construction planning documents, for public review on the site's website in the Site Document and Data section. The Record of Decision is expected to kick off intensive engagement with the local community including: • An increased presence of staff on the ground. • Regular communication with all stakeholders. • Focused engagement with the most affected communities. c. The Superfund Job Training Initiative Public Comment EPA Response Commenters raised the following input regarding the Superfund Job Training Init for the remedy: • This program should not be limited just to cultural monitoring The SuperJTI program is generally focused on providing training and qualifications for graduates to be eligible for cleanup-related positions within a three to six week training timeframe. Entry level jobs are generally the types of positions for which three to six 15 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Tribal members who undergo SuperJTI should not just be considered for entry level jobs like safety flagging but also higher-level jobs such as the trucking and equipment operating. • Those who go through the SuperJTI should not be the only Hazardous waste operation trained site workers that understand Tribal cultural sensitivity. Commenters requested that EPA ensure the program: • Be more extensive and offered to the broader community. • Enable community members to get a range of certifications and more employment opportunities. • Increase the understanding of the decision-making process including formal Tribal consultation and how Tribal input affects decisions. d. Timeline and Other Operable Units Public Comment EPA Response Commenters raised concerns about EPA's schedule for work on other parts of the site, cleanup timing for these other site components, and potential risk for community members. These comments/concerns below are organized by site area. For Operable Unit 1 commenters indicated that: • OU-1 s 2025 and 2030 timeline show EPA holding off on cleanup actions for the lake. • In the cleanup plan, EPA does not address the potential need to treat Herman Impoundment's water. Instead, the agency only says it will determine later. • After OU-1 's first phase of cleanup, EPA only anticipates Herman Impoundment's water quality will improve, but does consider if it doesn't improve in Phase 2 planning. • Also, EPA does not address the spring underlying the Waste Rock Dam and the potential need for water extraction. Instead, the agency only says it will determine later. • The post Phase 1 water monitoring results should be shared with community members and EPA should involve them with the related Phase 2 decisions. For Herman Impoundment commenters asked for: EPA acknowledges the comments and input. EPA aims to: • provide ongoing outreach and engagement for all work activities conducted at Superfund sites, • use a variety of communication strategies, • provide the community with resources through meetings, fact sheets and fliers, email communications, and informal on-site discussions, • focus on specific topics, areas of the site, or work activities, and • involve the community with comprehensive information for all aspects of site work. Although this ROD focuses on OU-1, EPA has ongoing activities to define the nature and extent of contamination and potential remedial options for the other site OUs encompassing OUs 2 and 4. EPA intends for progress on these OUs to move forward in parallel with work at OU-1 as the commenters recommended. EPA will continue to provide information about current and future work for other OUs. For more information, please visit the site's webpage: www.eDa.aov/suDerfund/sulDhurbankmercurv weeks of training can be expected to provide needed qualifications and so these are more often the focus of the program. Where community members have experience or existing qualification that might make the further 3 to 6 weeks of training sufficient for them to meet requirements for hiring above entry-level, EPA is fully supportive. If a significant pool of such candidates exist, EPA would be open to tailoring a SuperJTI module to these individuals upon request. The job training initiative: • combines classroom instruction with hands-on training exercises, and • provides graduates with technical skills to work on a broad range of construction projects, other environmental remediation projects and cleanup projects. 16 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Consideration of returning all waste to its original location and placing some of it in the impoundment since there is already existing contamination there. For Clear Lake and the North Wetlands commenters indicated that: • The Elem Indian Colony, Big Valley Rancheria, and Middletown Rancheria Tribal communities should continue to be involved in processes and decisions for all Operable Unites. All area Tribes utilize the lake and its resources. • Hopefully, EPA can manage all Operable Units in parallel, such as planning OU-2 and OU-4 cleanup during OU-l's cleanup implementation. • EPA needs to assure the community that OU-2 and OU-4's cleanups will not be delayed by the Operable Unit 1 cleanup. Written Public Comments I. National Historic Preservation Acts and Tribal Disenfranchisement (PAGE 18) a. EPA 2006 Cleanup Violations and Tribal Lawsuit Destruction of Tribal Identity, History and Artifacts, and Creation of Trauma b. Tribal Disenfranchisement c. Environmental Justice and Federal Indian Trust Responsibility II. Tribal and Natural Resources, Dances and Ceremonies (PAGE 21) a. Impacts to Tribal and Natural Resources and Traditional Lifeways b. Tribal Community Involvement Moving Forward III. Human Health and Environmental Risk Monitoring, Reduction, and Communications (PAGE 23) a. Cleanup Human Health Risk b. Northwest Rock and Waste Piles Movement c. Soil d. Air and Climate Change e. Water f. Traffic IV. Next Steps for Cleanup Decisions, Economics, Community Involvement, and Other Operable Units (PAGE 27) a. Next Steps and Cleanup Decisions (split into 13 specific technical comments) b. Proposed Plan Technical Issues (split into 11 specific technical comments) c. Economics and Superfund Job Training Initiative d. Timeline and Other Operable Units I. National Historic Preservation Acts and Tribal Disenfranchisement a. EPA 2006 Cleanup Violations and Tribal Lawsuit b. Destruction of Tribal Identity, History and Artifacts, and Creation of Trauma c. Environmental Justice and Federal Indian Trust Responsibility 17 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary a. EPA 2006 Cleanup Violations and Tribal Lawsuit Public Comment EPA Response NOTE: EPA received multiple comments about issues with the 2006 Elem Indian Colony Cleanup, the compliance of this action with the National Historic Preservation Act, this action's impact on Tribal resources, and a lack of consideration of Tribal input. These comments were substantially similar to the verbal comments on this subject discussed in the "verbal comments" section above. For this reason, only the parts of these comments that differ from those addressed above are paraphrased below. Commenters stated that future EPA actions at the site should be designed to ensure compliance with the National Historic Preservation Act. Commenters requested that any future EPA action at the site should include: • a program to reimburse the Tribe and public for the loss of cultural resources caused by EPA in the 2006 cleanup, • protection of cultural deposits both within and beneath the mine waste piles, • core sampling of waste rock piles and the Waste Rock Dam to assess resources beneath these piles, • Tribal Monitoring to observe the work, identify all soils beneath mine waste, and recommend waste removal transport routes to move waste in a way that avoids cultural sites or covers and protects them from damage by truck traffic, • Tribal monitoring from the community (living on the Elem Indian Colony) at all times that EPA or its contractors are on the Site. Please see Verbal Comment responses 1(a) through 1(d) above. EPA acknowledges and appreciates the comments regarding the impact of past EPA actions at the Site. The community's recollections and feedback will be used to inform the implementation of the remedial action described in the OU-1 Record Decision. EPA is committed to a robust evaluation of the potential impacts of the remedy on historic properties and tribal-cultural resources under the National Historic Preservation Act Section 106. EPA anticipates developing a memorandum of agreement with the Advisory Council on Historic Preservation and the State Office of Historic Preservation to ensure that the selected remedy is implemented in a manner that provides sufficient protection and/or mitigation for impacts to historic properties, including tribal-cultural resources. It is expected that this agreement will include a provision for tribal cultural monitoring of the remedial action. Pre-Design and Design-related investigations at the site are expected to include robust investigation of the presence of archaeological resources in areas of potential earth moving, including beneath waste piles in some cases. b. Destruction of Tribal Identity, History and Artifacts, and Creation of Trauma Public Comment EPA Response NOTE: Where comments on this subject were substantially similar to the verbal comments address in the "verbal comments" section above, they are not reiterated here. Commenters indicated that the site and land that surrounds it: • has been inhabited by Native Americans for more than 11,000 years, EPA acknowledges and appreciates the comments regarding the impact of past EPA actions at the Site. EPA acknowledges the long history and wide range of impacts for the Sulphur Bank Mine has had on the Tribal community and the EIC in particular. It is EPA's hope that the coordination, cooperation and dialog that is expected associated with the selected remedy in this ROD will provide a pathway to repair some of the harms described by commenters. The agency is committed to: 18 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • endured the "European arrival" and a history of broken promises ensued, • influenced by a treated that was wrongfully set and not updated to reflect the Tribe's right, • faced a slow destruction of the local ecosystem and Elan's way of life, and • its mining resources proved to be a crucial resource to the United States government during both World Wars, and • was used by the government and private industry at the expense of the health of the environment, the Tribe, and the rest of the local community. Commenters provided further details of the history of the EIC including: • By 1949, Elcm's sovereign territory was limited to the Tribe's current 48-acre Reservation (or "the EIC"). • During the 1960s and 1970s, the Bureau of Indian Affairs used mine waste as a construction material when building houses and roads on the EIC, and facilitated contamination spreading into and across the EIC and into the lake, and surrounding plants, animals, soil, and air. • The BIA disregarded the Tribe's numerous accounts of illness and disease affecting EIC residents and the local plants and animals. Commenters stated that the Elem and Tribal community are exhausted from the government's actions at the Site and view of Tribal rights and the devastation faced daily. Bradley Mining Company, the BIA (Bureau of Indian Affairs), and EPA: • made an agreement with the Elem government for them not to pursue litigation for past or future natural resource damage claims, • did not communicate with the Elem community about this agreement despite the greater impact for their day-to-life, • decided EPA would take on the obligation to clean up the site (because of Bradley Mining running out of money), and • slowed down the cleanup progress by deciding the site would be cleaned up using government money. Commenters requested that EPA needs to take the lead to: • correct historic wrong doings, • address the disenfranchisement of Tribal nations, and • correct the government's actions by: 19 • Continuing open dialog and close coordination with a range of Tribal voices in the community to facilitate equity and transparency. • Maintain communication channels with the most affected communities. • Ensure the future actions incorporate protections for historic properties and tribal-cultural resources that inform Tribal identity and history. For additional discussion of EPA's expectations and intentions to address this subject, please see Verbal Comment responses 1(a) through 1(d) above. ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary o repairing trust with Tribe's, o fix the reduction of Tribal power and will, and o provide compensation for the EIC peoples" suffering, the destruction of natural and cultural resources, and limiting the practice of traditional life ways. c. Environmental Justice and Federal Indian Trust Responsibility Public Comment EPA Response Commenters stated that the Elem tribe has experienced a disproportionate share of the environmental consequences from industrial, governmental, and commercial operations at the SBMM site. Commenters stated that this is a textbook example of what EPA would call an "overburdened community" and that the Federal Government has repeatedly failed to uphold its Federal Indian Trust Responsibility obligations. The commenter identified significant points of the site's early history including: • Early 1980s - Elem actively reached out to EPA for assistance to understand and cleanup the site's contamination. • 1983 - Elem invited members of federal, local, and state health agencies to discuss health hazards caused by contamination in Clear Lake, and the need for cleanup. • August 1990 - largely because of Elem's efforts, the was listed on the NPL. At that time however, the Tribe was not treated like a sovereign fighting to restore its lands. • 1990s and early 2000s - Elem had very little voice regarding the path forward for the cleanup. • The last 15 years - Elem has slowly become more involved. However, in part because of how CERCLA was written, still does not have the equal seat at the table with EPA and the State of California which environmental justice would require. The commenter stated that the Elem Tribe is fatigued from more than 30 years of fighting for cleanup of the contamination in their community. The Elem Tribe asserts that EPA: • facilitated a long and frustrating history on EPA's priority list, EPA acknowledges and appreciates these comments. The commenter's frustration regarding the Site's long history on EPA's National Priorities List is clear and understandable. There is a valid sense of urgency among all Stakeholders and the community to see EPA make significant progress at the site. EPA shares this sense of urgency and is working to expedite progress at the site including by moving this Record of Decision forward on an expedited schedule to take advantage of unique potential funding opportunities. Such urgency at this point cannot undo past harms but can hopefully minimize future impacts on the community. Though direct reference to Environmental Justice was erroneously absent from the Proposed Plan, it has strongly informed EPA's selected remedy, including numerous adjustments in approach intended to provide conservatism and increase the protectiveness of the remedy. Included amongst these are: • Use of the EIC's proposed "Reasonable Maximum Exposure Scenario" to represent the traditional tribal use scenario for EIC residents, • Use of the most protective toxicity value between EPA's IRIS database values and the State of California's Toxicity Criteria Rule values, • Use of a conservative bioavailability assumption for arsenic, • Assumption in the management of cumulative risk that the hazards posed by all COCs in soil can be summed, regardless of whether these contaminants are understood to affect the same parts of the body. These conservative/protective decisions collectively led to the cleanup levels identified in this ROD, many of which are set to the naturally occuring background concentration for the subject contaminant of concern. In so doing, EPA's selected remedy provides the maximum level of protectiveness possible while weighing the 9-Criteria in accordance with CERCLA's requirements. EPA is committed to: • continuing to address stakeholders' environmental justice concerns, • facilitating fair treatment, meaningful involvement, and equal access to the decision-making for Clear Lake communities most affected by the Sulphur Bank Mine Superfund site's contamination, and 20 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • is not complying with its obligations for environmental justice and Federal Indian Trust Responsibility, and • has historically failed to live up to those commitments to Elem. The Elem Tribal Government: • shares the widespread support to do what can reliably be done now, • appreciates the need to prioritize the need for financial and support assistance from the current administration, but • has a justified wariness of the way this opportunity and impact on timeline may change in the future. The commenter states that an expedited cleanup cannot satisfy the environmental justice needs of the EIC. Environmental justice goals will be most successfully reached through: • the most successful and protective cleanup possible, and • meaningfully involving all stakeholders and the community in the site cleanup and decision-making process. The commenter points out that the recommended cleanup plan makes no reference to environmental justice nor the longstanding issues for the Tribal people at the site. Despite EPA guidance recommending that Superfund cleanup plans include a discussion of "special community outreach related to environmental justice concerns," and a discussion of how environmental justice concerns influence the selection of the cleanup. using input to ensure the cleanup has the maximum long-term benefits for the Tribal community available under the law. II. Tribal and Natural Resources a. Impacts to Tribal Resources, Traditional Lifeways, and Tribal Community Involvement Moving Forward a. Impacts to Tribal and Natural Resources and Traditional Lifeways, and Tribal Community Involvement Moving Forward Public Comment EPA Response Commenters stated that since being listed on EPA's Superfund list, EPA has taken numerous actions intended to help the EIC community, but efforts intended to help the tribe's situation have also caused substantial additional suffering. To address impacts to the Tribal community, commenters requested that EPA should: • recognize the cleanup fatigue felt by the Tribal community when planning future activities and actions, EPA acknowledge the commenters" concerns regarding the impacts of environmental remediation at the Site. EPA recognizes: • the profound impacts the SBMM site has had and continues to have on the Tribal community, • the area's Tribal significance, • the sovereignty of the Elem Indian Colony, and • that tribes have cared for the land since time immemorial, and • that the area has immense cultural, ancestral, and ecological value. 21 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • compensate the tribe for past wrong doings, • improve protections for cultural resources, • ensure Tribal people can continue to practice their traditional lifeways, • coordinate more closely with Tribal residents, • provide the necessary resources for Tribal engagement in the cleanup process. Commenters request that EPA should: • Test and evaluate the marsh area to the Buckeye area, and • Evaluate where there was a dirt road from mine tailings created to gain access across the marsh to the Buckeye, commonly known as Buckeye Island (the property is part of the reservation land). The agency is committed to: • rebuilding trust to the extent possible with the both the Elem Indian Colony government and on colony residents, • continuing to facilitate and incorporate the EIC community's input into cleanup planning. Vegetation samples and results contained in the existing Human Health Risk Assessment were: • Gathered from oak trees and other deep-rooted vegetation in mine waste piles. They will need to be removed as a part of the cleanup, and not be allowed to reestablish because of the potential for their roots to break through the caps. • Evaluated from trees on the colony and in the surrounding area. Results indicated a minimal impact from storm water and other site contaminants. • Used to ensure cleanup planning reduces other resource and health impacts. This includes diverting contaminated storm water from the colony and allowing compliant water to flow into the lake. Tribal input will be used to: • Inform additional pre-cleanup sampling in close coordination with Tribal residents to target areas where Tules, cat tails, and sediments be more contaminated. • Understand typical foraging locations to communicate accurate human health risks to the Tribal community. EPA does not allow foraging on the mine waste covers because of the increased health risks. Post cleanup it will be safer on the mine site, but it is safest outside of the mine area. • Ensure tribal use of mine site is included in cleanup goals. The cleanup will make it safe for 12-hours per week Tribal use. EPA cannot allow trespassing on the site because of the site's private ownership and its contamination's high health risks. • Ensure that contaminant levels are at or below the area's naturally occuring levels. • Tailor soil cover seed mixes, and in some case seedlings, to facilitate site vegetation best suiting the community. EPA recognizes the need to support ongoing Tribal coordination and make every possible effort to build trust and reduce any impacts for Tribal resources and independence. The selected remedy has been structured with the intent to provided needed flexibility. It will allow new data and stakeholder input to inform the design and implementation of the remedy as the remedy moves forward. b. Impacts to Natural Resources Public Comment EPA Response 22 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Commenters made specific suggestions to allow the community to assess and revitalize the natural resources in the area of the SBMM site, including: • The Clear Lake Keys subdivision of homes across from the mine site is seeking grants to: o revitalize Schindler Creek and the channels, o revegetate the area with native plants, o control and remove invasive species of fish and plants, o dredge sediments, and o purchase land for conservation preservation. Commenters suggested that these projects could align with the recommended cleanup if dredged sediments generated could be used as clean fill to cover mine waste and cleaned up areas, Commenters also suggested that the remedial action could address natural resource impacts by assisting with the purchase wetlands for conservation, sponsoring the monitoring of water quality and wildlife. EPA is supportive of the commcntcr's goals to protect/re vitalize the natural resources of the area. Regarding potential reuse of dredged sediments, EPA has discussed the potential opportunities of such a collaboration with multiple parties, including State and local government. This possibility has been incorporated into the selected remedy, as described in Section 2.12. It is EPA's intention to develop staging areas and cap material stockpile locations early in the remedy implementation schedule to maximize the potential for such collaborations to occur. Specific proposals will be evaluated on their merits as details are provided to EPA. Other commenters have made recommendations regarding the seed mixes and transplants that may be planted on top of remediated areas and have likewise recommended California native species be used. EPA intends to follow this recommendation to the extent possible. Direct actions within Clear Lake or the North Wetlands to address Site impacts OUs 2 or 4 would be the subject of future decision document, but evaluations of remedial alternatives for these areas are likely to include consideration of habitat restoration elements. III. Human Health and Environmental Risk Monitoring, Reduction, and Communications a. Cleanup Human Health Risk b. Northwest Rock and Waste Piles Movement c. Soil d. Air and Climate Change e. Water f. Traffic a. Cleanup Human Health Risk Public Comment EPA Response Commenters requested that EPA should: • consider that Elem elders have become sick and even passed away from various illnesses that all had to do with either cancer or organ failure, and • address concerns that the carcinogenic materials and health issues are caused by the toxins introduced to soil and water. A commenter stated that EPA's Human Health Risk Assessment, provides two risk estimates for nearby residents" exposure to soil: • Non-tribal residents south of the site • Residents of the Elan's Reservation Please refer to comment responses in section III of the Verbal Comments above. As noted, the selected remedy in this ROD is intended to: • Address soil, air, and water-related risks to human health and the environment posed by OU-1 of the Site, including on the Elem Indian Colony, in the neighborhood off Sulphur Bank Mine Road, and on the mine site itself. • Entail covering exposed areas of mine waste and site-impacted soils with clean cover material that will prevent further direct exposure to the contaminants contained in these materials. • Enable safe use of portions of the mine site for traditional practices (such as hunting, wood collection, and other activities that occur on-foot). 23 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary The commenter points out that this evaluation found lower levels of risk (and thus presumably protection during risk management) for the EIC tribal population. The commenter acknowledges that EPA's reasoning for this relates to: • the past cleanups on the Elem Indian Colony, and • its characterizing of the natural soil conditions as being higher in arsenic and mercury (compared to the lower levels off colony when considering the risk for non-tribal residents). The commenter also states that EPA used different risk calculations for the risk assessment and cleanup standards in the following ways: • Risk Assessment - EPA calculated overall risks for different scenarios that people could come-into-contact with site contaminants (exposure scenarios). It found the risk for Tribal and non-Tribal residents to be about the same. • Cleanup standards - EPA used a risk measure called "incremental risk" that estimates risks and hazards by subtracting natural background risk from the overall risk of exposure scenarios. o Nearby nontribal residents - Risk was found to be 200 times higher the health risk level (threshold for concern) and the land qualified for a more protective cleanup standard. The commenter indicates that for Tribal residents the risk was classified as being due to natural conditions and therefore does not need to be cleaned up. Tribal residents were found to have no incremental risk because of the natural background level decision. EPA recognizes and acknowledges the data limitations that affected the findings of the 2020 Sitewide Human Health Risk Assessment, some of which included: • Limited contemporary data on the EIC, • Small sample size for vegetation samples, • Limited sediment data from which to construct a sediment background concentration, In addition, a key error was made in this risk assessment related to incremental risk that the commenter correctly points out. This error has been addressed by an Errata to the Human Health Risk Assessment included in the Administrative Record. In this errata EPA clarifies that the calculation and presentation of incremental risk in this manner is contrary to EPA guidance. While EPA regrets that this approach to risk evaluation was published, it appreciates willingness the Elem Indian Colony's technical team showed to working together to see that the issue was corrected. It is also significant to recognize the difference between risk assessment and risk management. While the approach presented in the risk assessment led to misleading conclusions, EPA does not and did not intend to leave site-related contamination in the residential areas of the EIC at concentrations known to result in unacceptable risk. The risk management decision make cleanup decisions at the scale of the individual residential lot means that much of the findings regarding average risk across the EIC did not result in an erroneous conclusion regarding the potential need for action on the EIC. To further address these and other concerns raised by the Elem Indian Colony, EPA engaged in a facilitated dialog with the EIC and its technical team (as referenced in Section 2.3.1), which led to further clarification to the risk management approach for the selected remedy. EPA appreciates the collaborative attitude brought to this dialog and believes the selected remedy described in this ROD provides the maximum level of protectiveness possible while weighing the 9-Criteria in accordance with CERCLA's requirements. Further, EPA has made specific commitments to the evaluation of Site risks associated with OUs 2 and 4. These will include (but are not limited to): • Collection of additional surface and subsurface soil samples to inform a reevaluation of background concentrations of COCs, • A Human Health Risk Assessment Addendum for OU4 incorporating additional soil, sediment, bird tissue, and vegetation samples, • An Ecological Risk Assessment Addendum for OU4, • Evaluation of the impacts of potential groundwater migration from OU1 into OU4. 24 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary a. North Waste Rock Pile and Waste Piles Movement Public Comment EPA Response Commenters stated that when driving in to the EIC from outside the area, the view is dominated by the massive waste piles on the mine site. They stated that the North Waste Rock Pile is: • an eye sore for the community, • not mentioned as a visual impact required remediation in the proposed cleanup, • should be considered for removal to minimize the waste leading to and from the reservation, recreate the view that the EIC's ancestors enjoyed, and provide more clean land for plants and animals to use. Also, commenters requested that EPA should: • consider the full excavation of mine waste described in Alternative 4, • include excavation of certain site areas and off-site disposal (there is no need to put more waste on waste and then cap it), and • evaluate all waste piles being removed completely or lowered before capping a part of the site. The ROD section 2.9 discussed the remedial alternatives evaluated by EPA. Section 2.10 presents the comparative analysis of these alternatives. Offsite disposal of waste was evaluated in Source Areas Alternative 4, but it is not included in the selected remedy for the reasons described in Section 2.9 and 2.10. In general EPA guidance/policy sets a strong preference against off-site disposal of Site-derived waste due to the tendency this remedial approach to simply move contamination from one community to another, while generating significant impacts related to the excavation, transport and disposal of these materials in the process. For the SBMM site, the offsite disposal Alternative 4 was found to rank poorly relative to other available alternatives when considered against the 9-criteria that EPA uses to evaluate cleanup alternatives. While selected remedy does not include major off-site of waste, EPA intends to implement the in a manner that is respectful of the expected future use of the site as "limited traditional tribal use." For this reason, revegetation of capped areas will aim to use native seed mixes to the extent possible. The selection of seed mixes is expected to be informed by dialog with the EIC community. b. Soil Public Comment EPA Response Commenters requested that EPA should: • evaluate the risk management related to the 1996-1997 Elem Indian Colony residential soils cleanups (EPA states that it removed the most highly contaminated soil and placed clean soil on top and indicates that additional soils cleanup on the Elem Indian Colony was performed in 2007), • communicate if the 1996 - 1997 residential soils cleanup removed all the most highly contaminated soils, both below and outside the building footprints, • clarify whether the most highly contaminated soils were removed from the Elem Indian Colony, and • investigate local sourcing of soil and utilizing it from the Spring Valley project via trucks, and/or dredging material from the Clearlake Oaks Keys via trucks or barge, • include an evaluation of the use of sediments from Schindler Creek and other channels in both the Phase 1 and 2 of the cleanup, EPA acknowledges the comments and input. The records supporting prior removal actions at the SBMM site as well as the complete administrative record for this remedial decision are available on the site webpage, should the public wish to review records regarding the extent of prior removal actions and the data that informed them. EPA's cleanup levels for the selected remedy are substantially more protective in most cases than those used for earlier removal actions. For this reason, data associated with those prior actions would not provide the appropriate basis for delineating the areas of the EIC requiring further remedial action. A substantial additional soil sampling effort on the EIC is anticipated as part of predesign and design activities. These data will be used to determine where and how much excavation and capping is needed in the residential and common areas of the EIC. EPA will continue to work closely with the community, using a variety of outreach approaches, to communicate about health risks associated with the Site and receive feedback regarding preferred approaches to the remedy implementation for individual lots identified as requiring action. 25 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • continue to the 2010 discuss with the keys POA from ten years ago, the study completed in 2009, and the potential need for additional sampling, • coordinate with the Blue-Ribbon Committee about its proposed dredging project and the interest in the dredged materials to address concerns of committee members. As noted in the response to written comment 11(b) above, EPA expects to evaluate the use of dredge sediments as a potential capping material during the design of the remedy and is aiming to sequence work at the site in a manner that maximizes opportunity to reuse clean soil/sediments that might be possible to barge across Clear Lake in order to reduce impacts and costs associated with hauling of soil to the site by truck. c. Air and Climate Change Public Comments EPA Response Commenters stated that the cleanup plan proposes moving large amounts of soil with high truck traffic over a few year period that creates environmental health risks. The commenters requested that EPA should: • Describe dust control and air monitoring measures at the site and along the truck routes including those that are based on the area's high winds, • Evaluate escaping gases; as in H2S, carbon dioxide, etc, • share knowledge and address concerns over the toxic that is invisible, and • reduce airborne risks relate to soils being disturbed from equipment because they are dry and very powdery. Please refer to the verbal comment responses III(c) and 111(f) above. EPA received multiple comments about dust control and air emissions. As indicated, EPA expects to develop site-specific plans to address these potential impacts associated with the selected remedy during the remedial design process. d. Water Public Comment EPA Response Commenters request that EPA should: • account for surface water/storm management, and • evaluate the relatively short distance to the drinking water intake for the Clearlake Oaks water treatment plant. Please refer to the verbal comment response 111(d). A storm water management system will be a major part of the cleanup design. EPA is coordinating very closely with the state's Central Valley Regional Water Quality Control Board (CVRWQCB) and the Department of Toxic Substances Control (DTSC) to ensure: • Appropriate storm water management and protection during the cleanup, • Compliance with all necessary regulations (Applicable or Relevant and Appropriate Requirements - ARARs) for the consolidation, capping, and disposal of Site waste as it relates to the separation from and impact on water resources. • Waste piles' elevation and slope are managed effectively and not causing unacceptable degradation of water quality issues due to issues such as ponding on waste management areas. 26 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Regarding OU-1 potential impacts to the water of Clear Lake and its fish, the agency is: • Conducting the OU-1 cleanup activities to address sources of contamination to OUs 2 and 4, while also continuing to evaluate contamination and remedial alternatives available for OU-2 and OU-4. • Collaborating with federal, state, and local partners including with the US Geological Survey, the Blue-Ribbon Committee for the Rehabilitation for Clear Lake, and Tribes that surround the lake. e. Traffic Public Comment EPA Response Commenters requested that EPA should: • provide information about the clean soil fill sources, • explain truck routes and schedules, • conduct outreach (particularly direct mail to all property owners and residents of Sulphur Bank Rd, Sulphur Bank Mine Rd, Orchard Shores, and Lake Village Estates), • ensure that traffic is routed east of Clearlake Oaks (and not along the Clear Lake north shore of Hwy 20), • place appropriate traffic control signs that indicate truck traffic at either end of Sulphur Bank Drive, • coordinate with Lake County Public Works on a civil engineering and traffic report on Sulphur Bank Road (considering the width of the road and its ability to handle the weight of the trucks), • consider road accommodations and or modifications that may be required to prevent any road maintenance expense from the county (especially related to the repaving of Sulphur Bank Road, and • manage safety related to the use of Sulphur Bank Road (by acquiring land from Dennis Pluth to reconstruct the current dirt road from the entrance of the reservation road to Hwy 20). Please refer to the verbal comment response 111(f). EPA appreciates these recommendations. As noted, site-specific plans, including a traffic management plan, are expected to be developed during the remedy design process. EPA will continue to provide the community updates about these plans and what options are available to mitigate the impacts of remedy implementation on the community. IV. Next Steps for Cleanup Decisions, Proposed Plan Technical Issues, Economics and the Superfund Job Training Initiative, and Timeline and Other Operable Units a. Next Steps and Cleanup Decisions 1. Cleanup Option Evaluations - State Law and Cost Savings - Versus - Sufficiently Protecting Human Health and the Environment 2. Soil Cap Option Evaluation 3. Waste Rock Dam Evaluation 4. Required State Laws (Applicable or Relevant and Appropriate Requirements - ARARs) 5. Cost Evaluation 27 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary 6. State's Unfair Power 7. Law's Lack of Requirement for Tribes' Cleanup Cost Contribution 8. Recommended Cleanup and the Multiagency Team 9. Uncertainty in EPA's Recommended Cleanup 10. Elem's Technical Concerns, Preferred Cleanup, and Reasoning 11. EPA's Obligation to the Tribe and Lack of Responsiveness 12. EPA Decision Shortcomings and Public Suggestions 13. Meaningful Tribal Involvement b. Proposed Plan Technical Issues 1. Contaminant Level Cleanup Goals 2. Natural or Background Contaminant Levels 3. Soil Sampling and Studies 4. Mercury Bioavailability Factor, Speciation Data, and Soluable Fraction's Effect on the Human Health Risk Assessment 5. Sediment Samplings 6. Human Health Risks and Concerns 7. Soil and Rock Cleanup Goals 8. Compliance with Clear Lake Mercury Level Entering Clear Lake with Surface or Groundwater Limit Law 9. Compliance with State Law for Site Surface Water Management Compliance with State Law 10. Compliance with Mine Waste Management Laws 11. Other Technical Concerns i. Possible Ground Water Flow into Clear Lake from Locations other than the Waste Rock Dam ii. No Numerical Cleanup Goals for Ground Water hi. No pH Cleanup Goals iv. No Mercury Flow Monitoring System v. Cleaning Up Parts of the Waste Rock Dam in Place vi. Mine Site and Residential Soils' Cleanup Connection to Clear Lake vii. Herman Impoundment's Mine Waste viii. Possible Contamination Underneath Mine Waste Piles ix. Sources of Mine Waste Contamination x. Recommended Cleanup Glossary of Terms xi. Selection of EPA's Recommended Cleanup c. Economics and Superfund Job Training Initiative d. Timeline and Other Operable Units a. Next Steps and Cleanup Decisions 1. Cleanup Option Evaluations - State Law and Cost Savings - Versus - Sufficiently Protecting Human Health and the Environment 2. Soil Cap Option Evaluation 3. Waste Rock Dam Evaluation 4. Required State Laws (Applicable or Relevant and Appropriate Requirements - ARARs) 5. Cost Evaluation 6. State's Unfair Power 7. Law's Lack of Requirement for Tribes' Cleanup Cost Contribution 28 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary 8. Recommended Cleanup and the Multiagency Team 9. Uncertainty in EPA's Recommended Cleanup 10. Elan's Technical Concerns, Preferred Cleanup, and Reasoning 11. EPA's Obligation to the Tribe and Lack of Responsiveness 12. EPA Decision Shortcomings and Public Suggestions 13. Meaningful Tribal Involvement 1. Cleanup Option Evaluations - State Law and Cost Savings - Versus - Sufficiently Protecting Human Health and the Environment Public Comment EPA Response Commenters stated that EPA's recommended cleanup plan does not: have an accurate evaluation of the nine criteria used to make cleanup decisions (required by the National Contingency Plan, and the Comprehensive Environmental Response and Liability Act, CERCLA, in Section III.F). Thereby leading to the creation of an ineffective cleanup that does not comply with the law. They also state that EPA does not explain the evaluation of two of the nine criteria use to recommend the cleanup (required by law - the National Contingency Plan). They are: • What does the Tribe or state think? • What does the community think? Commenters requested that EPA should: • support the claim, • provide an evaluation of the criteria, • explain when they do not influence the recommendation, or • provide specific basis for the states or the tribe's position and the ways it influenced cleanup decisions. Commenters stated that it seems impossible for the cleanup recommendation to have "taken into consideration" the community's feedback since: • EPA's consideration of public comments happened before the publication of the recommended cleanup plan, and • It did not provide an analysis of the criteria. EPA acknowledges the comment and input. The 2006 Feasibility Study and 2021 Focused Feasibility Study both evaluated remedial alternatives against CERCLA's 9 Criteria. Alternatives that failed to meet the threshold criteria were eliminated from further consideration. The balancing criteria were then used to compare between alternatives. Please refer to Sections 2.9 and 2.10 of the ROD, as well as the Feasibility and Focused Feasibility Studies for further detail. Community input is an essential part of the CERCLA process. EPA is committed to continuing to improve communication, outreach, and coordination with the local community. EPA will continue to provide information about: • site investigations, • identification and evaluation of cleanup alternatives, • health and environmental risks, and • ongoing and future environmental response actions. EPA circulated the OU-1 Proposed Plan for an extended 90-day public participation and comment period (from January 10th to April 11th 2023) in an effort to bring public input into the decision making process. During the community events, question-and- answer sessions, open houses, and formal public hearings hosted by EPA regarding the Proposed Plan, EPA received verbal comments on the Proposed Plan. Written comments were also submitted by numerous parties. State, tribal, and community input on the Proposed Plan has informed numerous adjustments in the planned approach to the remedy including (but not limited to): • Elimination of the 2-Phased structure originally proposed in favor of selection of the larger excavation extent for the WRD to provide greater conservatism and assurance of the success of the remedy, • Adjustments in cleanup levels to provide greater protectiveness for at-risk community members, • Additional requirements for the approach to backfilling of the Northwest Pit, • Additional monitoring requirements for groundwater leaving the site, 29 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Commitments to development of several plans during remedy design including those focusing on traffic management and dust management. 2. Soil Cap Option Evaluation -Evapotranspirative - Deep Rooted Shrubs and Trees Public Comment EPA Response Commenters stated that the evaluation: • indicates risk from past studies (acorns that indicated high levels of arsenic), • may cause roots to grow into the mine waste and uptake contaminants, and • increase health risks. Commenters requested that EPA should: • revise cap evaluation, • increase the minimum 2-foot soil layer, and • consider all risk including future ones from deep-rooted shrubs and trees. The acorns samples for the Human Health Risk Assessment were from trees rooted entirely in mine waste and therefore are expected to represent the high-end of possible risks posed by acorns produced by oaks growing for site-impacted areas. Any such trees growing atop waste piles will need to be removed as part of the remedy in order for the engineered caps to be installed. Where a RCRA-type cap is placed, deep rooted vegetation such as oak trees will not be allowed to become established. The Operations and Maintenance of the remedy will include removal of any oak, grey pine, manzanita and other deep-rooted plant that might germinate on top of these areas. During design EPA will weigh a range of factors to determine where the various capping technologies included in the selected remedy will be used. The possibility that oaks growing on an evapo-transpirative cap might accumulate arsenic in their acorns to concentrations that could cause human health risk will be incorporated into the design of the remedy. In some areas, the expected future use of the mine site of "limited traditional tribal use" may need to include restrictions against the collection of edible plants to ensure protectiveness. 3. Waste Rock Dam Evaluation Public Comment EPA Response Commenters stated that EPA considers doing nothing or no action, and: • states the option will include fencing and site monitoring, and • suggests it will cost zero dollars. They requested that: • revise to include anticipated costs for fencing and monitoring, and • correct any related inaccuracies. The detailed evaluation of WRD alternatives is presented in the 2021 Focused Feasibility Study and is summarized in Section 2.9 and 2.10 of the ROD. As the selected remedy for the WRD was not the "no action" alternative, response to this comment is beyond the scope of this responsiveness summary. 4. Required State Laws (Applicable or Relevant and Appropriate Requirements - ARARs) Evaluation Public Comment EPA Response Commenters stated that EPA cites only two regulations impacting the cleanup recommendation: • California Code of Regulations Title 27, Division 2 - Consolidated Regulations for Treatment, Storage, Processing or Disposal of Solid Waste and California Water; and The commenters confusion is understandable, however the two regulations cited are referred to in this section of the Proposed Plan as the State regulations "most significantly influencing" the need for action and extent of remedial action evaluated for OU-1. This section of the Proposed Plan was not intended to be a comprehensive presentation of the Applicable or Relevant and Appropriate Requirements for this remedy. For a comprehensive presentation of the ARARs and their consequence for the selected remedy, please see Table A-l attached to this ROD. 30 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • Code Section 13240-13243 - Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Mercury in Clear Lake) Commenters requested that EPA should explain, in more detail: • the other ARARs, and • their influence the cleanup decisions. 5. Recommended Cleanup Cost Evaluation Public Comment EPA Response Commenters referring to the cost evaluation for the Proposed Plan indicated that EPA should: • consider that the recommended cleanup improperly prioritizes cost reduction over effectiveness, • ensure the cleanup meets the NCP threshold criteria (overall protection of human health and the environment), • explain if cost or cost savings justifies if the cleanup fails to meet the criteria, • address Elan's serious concern that they will not be met because the cleanup approach is different than those typically implemented that have a long history of success, and assure the community the cleanup is designed to protect human health and the environment, and not to reduce operation and maintenance costs and secure state buy-in. Commenters also noted that both 1.5 percent and 7 percent discount rates are used to evaluate for the long-term operations and maintenance costs for the remedy. This is said to potentially influence the recommended cleanup decision. The 2021 Focused Feasibility Study included a detailed cost evaluation based upon 2016 dollars. These costs, adjusted for inflation, informed the Proposed Plan and, further refined based on the selected remedy, used to inform the cost estimate in Table 2-9 of this ROD. Cleanup cost is a balancing criterion that is considered only after the threshold criteria of protectiveness and ARARs compliance is met. A remedy that achieves cost savings at the expense of meeting the NCP's requirements regarding protectiveness would be considered a failed remedy and the agency would need to evaluate further remedial action to provide sufficient protectiveness. The selected remedy's general approach of source control via consolidation and capping and preventing water from interacting with contaminated waste before leaving the site are both a fundamental approaches to remediating contamination of the sort present at the SBMM site. EPA's intent in selecting this approach is not to minimize costs, but to implement an effective remedy that addresses the sources of contamination, rather than treating waters after they have been impacted. 6. State's Unfair Power Public Comment EPA Response Commenters stated that the State of California has unfair "veto power" under Superfund law (Comprehensive Environmental Response Compensation and Liability Act). It reduces the Elem Tribe's influence on cleanup decisions. The comment references an amendment to the law intended to: • increase tribal participation in the Superfund process, • mandate equal treatment of tribes and states, and EPA acknowledges the substantial role that States play Superfund sites and notably for "fund-lead" NPL sites where the State has a cost-share obligation. The Elem Indian Colony has also played a prominent role in the CERCLA process for the SBMM site over its history. The EIC, DTSC, and CV Waterboard were considered the primary stakeholder agencies with whom EPA worked closely on the Focused Feasibility Study, Pre-Mining Baseline Study, Human Health Risk Assessment, and numerous other site documents that have influenced this remedy decision. EPA will 31 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • required states to pay for post operation and maintenance, and continue to work in close partnership with key stakeholders as the project moves into costs (while Tribes are not); however, it did not actually benefit remedy design and implementation, them. EPA took steps to specifically bring the EIC's input into the decision-making process for this ROD via government-to-government consultation, facilitated meetings regarding EIC comments on the Proposed Plan, and extensive staff-level coordination and collaboration. Please see responses to earlier comments for ways in which the selected remedy was adjusted to specifically address comments and concerns raised by the EIC. 7. Law's Lack of Requirement for Tribes' Cleanup Cost Contribution Public Comment EPA Response Commenters stated that the State: • have unfair power in decision-making, and • can withhold their cleanup approval to prevent its start (if they are not willing to pay the extra cost that may come with a more protective cleanup). This means EPA can: • justify not meetings its obligation to ensure tribes" protection by the most scientifically sound cleanup (Federal Indian Trust Responsibility), and • cleanups can move forward with the cheapest option. Commenters requested that EPA should: • take a leadership role resolving tribal and state preferences, • determine equitable solutions, and • uphold the government's Federal Indian Trust Responsibility. Please see responses above including those for: Verbal Comments 1(a) through (d), and written comments 1(c), and IV(a)6 above. EPA will continue to coordinate closely with all key stakeholders throughout the CERCLA process for the Site. The selected remedy will remediate soils on the Elem Indian Colony to background for all contaminants of concern except thallium (for which the proposed cleanup level at a hazard index equal to 1 already presents significant practical challenges due to equipment detection limits). The selected remedy described in this ROD ensures protectiveness for current and future land uses while weighing the 9-Criteria in accordance with CERCLA"s requirements. 8. Recommended Cleanup and the Multiagency Team Public Comment EPA Response Commenters stated that in the recommended cleanup, EPA inaccurately describes the "Multi-Agency Team" ((EPA, the state, and the Elem Tribe), suggesting this "Team" worked together from a position of equal power when the unfortunate reality was these stakeholders rarely communicated as a group, have substantial disagreements, and often EPA and the state agree, but Elem did not. Commenters requested that EPA should: • do not understate the Tribe's objections, DTSC, the CV Waterboard, and the EIC Environmental Protection Agency participated in over 20 working sessions, some of which were full day meetings, to collaborate on the development and finalization of the 2021 Focused Feasibility Study. Since then, all three of these key stakeholders have been heavily involved in the dialog that informed the Proposed Plan and the eventual selected remedy. It was not EPA's intent to imply that these parties consistently agreed throughout this process, but to document that these three key stakeholders played a major and pivotal role in informing the remedial approach. 32 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary correct the overstated sense of unity implied by the term Multi- Agency Team, and ensure that the inaccurate representation does not sway public option and reduce the Tribe's influence on the cleanup decision. EPA acknowledges the objections raised by the EIC on the Proposed Plan and has continued to work with the EIC to address as many concerns as possible. The ROD includes multiple adjustments to address the EIC's comments. EPA also acknowledges that the EIC's concurrence letter on this ROD has conveyed some ongoing reservations about some elements of the Selected Remedy. EPA has devoted considerable attention to working with key stakeholders to select a protective remediation approach that is consistent with CERCLA remedy selection criteria, including a balanced consideration of diverse input from multiple stakeholders. 9. Uncertainty in EPA's Recommended Cleanup Public Comment EPA Response Commenters stated that EPA has: • created a "wait and see" cleanup approach, • acknowledged uncertainty about the cleanup's potential effectiveness, and • characterized it as unavoidable. Commenters requested that EPA should: • more effectively explain the rationale for the uncertainty, and • what will happen if the cleanup does not work and if will increased future costs may be necessary to correct it. Tribal people, residents, and elders strongly opposed no cleanup at this time, and many are in favor of the most effective and protectible option of complete excavation and off-site disposal (SA Alternative 4). Please see comment responses above such the response to Written Comment V(a)l. As indicated, State, tribal, and community input on the Proposed Plan has informed numerous adjustments in the planned approach to the remedy including (but not limited to): • Elimination of the 2-Phased structure originally proposed in favor of selection of the larger excavation extent for the WRD to provide greater conservatism and assurance of the success of the remedy, • Adjustments in cleanup levels to provide greater protectiveness for at-risk community members, • Additional requirements for the approach to backfilling of the Northwest Pit, • Additional monitoring requirements for groundwater leaving the site, These adjustments were made in-part to increase the protectiveness of the remedy and reduce potential uncertainty. 10. Elem's Technical Concerns, Preferred Cleanup Option, and Reasoning Public Comment EPA Response Commenters stated that if there is uncertainty with the cleanup, the tribe finds it unacceptable to move forward with the cheapest option when there are other more reliable ones. Commenters requested that EPA should not move forward with the cleanup, if it may: • result in failure, • be less protective than required by law, • continue to negatively impact Tribal physical, mental, and spiritual health, • increase the 1 need for additional cleanups and more costs, or Consistent with the Superfund process, EPA makes remediation decisions based on the CERCLA 9-Point Criteria. Cost is one of the nine criteria used in making remedy decisions. As noted in response to previous comments, adjustments to the selected remedy have been made in response to State, tribal and community comments. EPA believes the selected remedy described in this ROD provides the maximum level of protectiveness possible while weighing the 9-Criteria in accordance with CERCLA's requirements. In response to EIC requests for resolution to intractable disputes about elements the preferred remedy, EPA engaged in a 3-meeting series facilitated by a professional facilitation team beginning in July 2023. This meeting series provided a venue for 33 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary 11. EPA's Obligation to the Tribe, and Lack of Responsiveness Public Comment EPA Response • delay the timeline for the site to reach mercury level contributions to several key issues of concern for the EIC to be presented in greater detail. This assisted Clear Lake that allow its full restoration. EPA in making informed decisions on the adjustments needed to the selected remedy to better address EIC's input. The fact that the recommended cleanup includes a third cleanup of "residential soils" on Elan's Reservation suggests that: • past cleanups were completed without the most protective levels now being proposed, • residents have been exposed to unacceptable risk for the last 26 years, • they have already paid the price of failed cost saving techniques, and • government action is contrary to environmental justice and the Federal Indian Trust Responsibility, Commenters request that EPA: • create effective and long-term cleanup goals, • ensure the soils are sufficiently protective, • expand where needed, and • assure the community the cleanup will be maintained. • Address the following timeline showing tribal disagreements: o June 2019 - Elem requested Alternative Dispute Resolution to agree on a technically sound mine cleanup, o October 2019 - Elem entered EPA's proposed Strategic Planning Sessions approach, o December 2019 - Elem raised the same concerns from June 2019 at the first session meeting, o January 2020 to April 2020 - Elem did not have a technical advisor to engage with stakeholders, o Mid-April 2020 - Elem began receiving support from a new technical advisor through EPA's Technical Assistance Services for Communities Program (TASC). o May 2020 to December 2020 - Elem's TASC advisor wrote memos expressing significant technical concerns with the cleanup option evaluation, o April 2022 - The advisor wrote a sixth "TASC memo" to restate the first five memos' concerns. Ultimately, EPA responded in a letter without new sampling, studies, or revisions to technical documents. 34 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Commenters stated that EPA is confronted with the dilemma of: • moving the cleanup forward, • facing the technical disagreements among the stakeholders, • not being able to prevent the state from withholding approval (for various reasons including cost), and • fulfilling its Federal Indian Trust Responsibility to develop a protective cleanup, restore traditional lifeways, and meaningfully involving the Elem Tribe along the way. See comment response V(a)10 above. EPA has sought to address the EIC's concerns to the maximum extent possible under the law. Commenters requested that EPA should: • consider the Tribe's history of unaddressed health hazards, • reduce health concerns with certainty, • assure there will be an end to the Superfund cleanup process, • address the technical concerns and that cleanup decisions are no longer being made based on cost, • future generations will not be burdened with explaining cleanup history to new EPA employees, • communicate the resolve of the Tribe's differing views of the state, and • ensure the Tribe's involvement is "meaningful/' 12. EPA Decision Shortcomings and Public Suggestions Public Comment EPA Response Commenters stated that in cleanup planning, EPA is delaying key decisions until the start of data gathering plans and the design phase. These decisions were: • Unnecessarily deferred to the design stage, • not addressed in the recommended cleanup, and • not subject to public review. Commenters request that EPA should: • Continue sharing knowledge, science policies and procedures, and cleanup decisions that may affect residents (including in coordination with USGS Officials), • follow-up about actions and progress, • address all the complex issues at once including: o cultural resource and heritage protection of tribal, Chinese, and European artifacts (required of contractors and should include youth outreach and education), o obligations to tribe's (including meaningful involvement, and EPA acknowledges these comments. As indicated in prior comment responses, adjustments in remedial approach between the Proposed Plan and ROD have led to the elimination of the 2-phased remedy structure this comment refers to and recommends against. The formal cleanup decision in this Record of Decision: • is critical to cutting off site-related mercury entering Clear Lake, • protects the community and environment from the 2.5 million tons of mine waste and contaminated soil on-site, and • limits mercury entering Clear Lake to allow mercury levels in sediments and fish to decrease overtime, and help EPA determine the cleanup needed for the lake. The selected remedy provides the maximum level of protectiveness possible while weighing the 9-Criteria in accordance with CERCLA's requirements while also aiming to move the cleanup forward for the whole site as urgently as possible. The cleanup will focus on reducing the amount of contamination that leaves the site (source material). EPA has: 35 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary o technical concerns and cleanup uncertainty. • coordinated extensively with affected stakeholders to balance state and local needs, • heard from the community about the need for this cleanup to move forward urgently, and • explained that the cleanup chosen will achieve the necessary balance between: o remaining uncertainties, and o the urgent need to protect Clear Lake and the community from site-related contamination. 13. Meaningful Tribal Involvement Public Comment EPA Response Commenters requested that EPA better explain: • the evaluation of the EIC's preferred cleanup alternatives 8 and 8 A • the applicability of the California Surface Mining and Reclamation Act Regulations, • the potential future need to backfilling of the Herman Impoundment with mine waste in a future cleanup (if the proposed one fails), and • Deferring cleanup decisions and compliance until after the cleanup's completion. Commenters requested that EPA should: • Address the cleanup's uncertainty with: o changes in the formal cleanup decision or a development of a cleanup review plan, o an agreed upon future decision-making role of the Elem Indian Colony government, o explain the impact if the tribe's does not respond or opposes on cleanup decisions, or o establish a committee comprised of tribal members for ongoing progress talks and plan evaluation. • In considering the Elem Indian Colony, EPA should: o not understate Elem's opposition because of the tribe's well- documented technical concerns that have not been responded to, o address the concerns about the portrayal of ""Multi-Agency Team," o consider guidance that the formal cleanup decision should include a summary of the support agency's agreement or disagreements, and o respond to the tribe's concerns the recommended cleanup and past concerns that remain unresolved. • When moving the cleanup forward, EPA needs to: The analysis of EIC tribal alternatives 8 and 8A were incorporated into the final 2021 Focused Feasibility Study. These alternatives were evaluated and found to be infeasible and/or rank poorly against the other FFS alternatives for a range of reasons, most particularly because they would violate (or require waiving of) several State ARARs, be far more difficult to implement that the FFS alternatives and provide no effectiveness benefit supported by current data. The complete evaluation of ARARs is contained in Table A-l. The California Surface Mining and Reclamation Act regulations were found not to be applicable to the SBMM site. The State of California, who has direct jurisdiction over this regulation, concurred with this conclusion. As noted in prior responses, numerous adjustments to the remedial approach were made in response to State, tribal and community input on the Proposed Plan. These changes reduce uncertainty, increase protectiveness, and aim to resolve the concerns/objections of some parties. For response to the comment regarding the sourcing of clean cover material, see the response to comment III(c) above which indicates that remedial design will evaluate this potential source of cap material. 36 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary o continue to study and monitor the long-term effects, o be held accountable for the effects on the people of the Elem Indian Colony, o address issues of officials coming and going that have not facilitated good communication, and o support the tribal government and with a deep connection to the land. • For clean fill soil sourcing, EPA should: o investigate utilizing soil fill from the Spring Valley project and/or dredging material from the Clearlake Oaks Keys via trucks or barge, and o consider local sourcing or barge delivery to decrease air quality issues. b. Proposed Plan Technical Issues 1. Contaminant Level Cleanup Goals 2. Natural or Background Contaminant Levels 3. Soil Sampling and Studies 4. Mercury Bioavailability Factor, Speciation Data, and Soluable Fraction's Effect on the Human Health Risk Assessment 5. Sediment Samplings 6. Human Health Risks and Concerns 7. Soil and Rock Cleanup Goals 8. Compliance with Clear Lake Mercury Level Entering Clear Lake with Surface or Groundwater Limit Law 9. Compliance with State Law for Site Surface Water Management Compliance with State Law 10. Compliance with Mine Waste Management Laws 11. Other Technical Concerns i. Possible Ground Water Flow into Clear Lake from Locations other than the Waste Rock Dam ii. No Numerical Cleanup Goals for Ground Water iii. No pH Cleanup Goals iv. No Mercury Flow Monitoring System v. Cleaning Up Parts of the Waste Rock Dam in Place vi. Mine Site and Residential Soils" Cleanup Connection to Clear Lake vii. Herman Impoundment's Mine Waste viii. Possible Contamination Underneath Mine Waste Piles ix. Sources of Mine Waste Contamination X. Recommended Cleanup Glossary of Terms xi. Selection of EPA's Recommended Cleanup 1. Contaminant Level Cleanup Goals Public Comment EPA Response 37 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Commenters state that, unfortunately, certain parts of EPA's recommended cleanup seem to be guided by the lowest standards permitted by law. When determining cleanup level goals: • it can be difficult to differentiate between possibly high natural levels (background) from those caused by the human activities like mining, and • EPA guidance states that high natural levels should be considered in contaminant risk management. They also stated that EPA's recommended cleanup: • is not protective of human health and the environment, • overestimates what the natural-occuring contaminant levels are before mining (pre-mining background), and • used overestimated natural levels that led to less protective cleanup standards. 2. Natural or Background Contaminant Levels Public Comment EPA Response Commenters stated that for the mine's cleanup, EPA has: • evaluated what natural (background) levels of the contaminants of concern at the site were before the mine had been developed, • had challenges assessing the naturally-occuring contaminant levels because the area is high with metals (common at mining sites), • acknowledged the uncertainty about whether high contaminant levels are from mining or natural conditions, and • communicated it may not be able to completely reduce exposure risks (because it legally) cannot cleanup below natural levels. Commenters requested that EPA should: • do not rely on assumptions of background made in studies that informed the recommended cleanup plan, and • use a more common and protective approach by assuming that elevated levels of mercury and arsenic in water, soil, rocks, and sediment are mine related. EPA acknowledges these comments. The 2021 "Final Baseline Sampling of Surface Soils in Non-mined Areas to Estimate Pre-mining Conditions Technical Memorandum" referred to as the Pre-Mining Baseline Report provides the best available estimate of background levels of COC for the site. Section 2.5.3.4 of the ROD discusses this study and the representativeness of its findings for use as the background concentrations for surface soils. Further, EPA has committed to a further evaluation of background concentrations of our COCs at the site as part of pre-design work for OU-1 and remedial investigation activities for OU-4. The ROD includes language that provides for the potential need to adjust cleanup levels if this further evaluation of background demonstrates a need to do so. 3. Soil Sampling and Background Study Please refer to the response to Written Comment 111(a) above. The selected remedy will remediate soils on the Elem Indian Colony to background for all contaminants of concern except thallium (for which the proposed cleanup level at a hazard index equal to 1 already presents significant practical challenges due to equipment detection limits). The selected remedy described in this ROD provides the maximum level of protectiveness possible while weighing the 9-Criteria in accordance with CERCLA's requirements. Further, EPA has committed to a further evaluation of background concentrations of our COCs at the site as part of pre-design work for OU-1 and remedial investigation activities for OU-4. The ROD includes language that provides for the potential need to adjust cleanup levels if this further evaluation of background demonstrates a need to do so. 38 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Public Comment EPA Response Commenters stated that, considering the mining conditions at the Sulphur Bank Mine: • most of the ore was underground and confined to veins, • there does not seem to be evidence of desirable mining metals at the surface outside of the mine area, and • so, it is unlikely that off-mine naturally-occuring levels would be higher that those of typical California soils. Commenters requested that EPA should: • Evaluate mining considerations by drilling deep through the surface of soil into the bedrock of off-mine areas to evaluate if: o soil is found to have high levels of mercury and arsenic, and o bedrock does not, then o the soil contaminant levels are almost certainly mining-related. • Respond to the Tribe's concerns (from EPA's Technical Assistance Supporting Communities Program) that such a background study (described above): o has not yet occurred, o may be completed as part of the wetland area east of the mine's investigation, and, instead, o will be useful, now, for the mine area and residential soils cleanup decision-making. • Correct the following background study (Baseline Memo) inadequacies: o pre-mining estimates for soil and rock are inaccurate, o soil sampling data is not consistent uncontaminated sample data, o the existing background study does not follow requirements that background sample locations must be in areas: ¦ without site contamination, and ¦ with similar conditions to the site (EPA's Risk Assessment Guidance), o The historic sample locations (Summary of Historic Soil Data - Appendix F) were chosen incorrectly and instead were: ¦ taken "along dirt road, possible waste rock fill," and ¦ labeled as "road fill" or "near discharge from culverts," and ¦ these sample that consist in who or part of road fill or waste rock are not natural soils and not appropriate for the analysis. • Discount any of the potentially compromised samples (such as those described above) and exclude them from the background statistical because they may: EPA acknowledges these comments and has made efforts to address them in the content of the ROD, including in sections 2.5.3.4, 2.8.1, and 2.12. ROD Section 2.5.12 describes the Pre-Mining Baseline Study and the representativeness of its findings. Regarding the possibility that the Pre-Mining Baseline study was biased by site-related releases of contaminants, EPA acknowledges this concern. It was a factor weighed by EPA during the development of that Study. It was determined upon a review of the geologic conditions at the site and a review of potentially similar sites in the area, that the conditions at the site were not well represented by any known off-site proxy location. For this reason, EPA attempted to sample as close to the unique geologic units present at the mine site as possible, while taking steps to try to control for the problem of potential sample bias due to releases from the site. These measures to control for bias were reviewed by the EIC's technical advisor at the time and included: • incorporating EIC technical advisor input into the selection of sampling locations and methodologies, • visual inspection for visible mine waste during sample collection, • elimination of the potentially biased samples, including those the commenter refers to from near roads and culverts, • elimination of high outliners in the dataset under the conservative assumption they represented site-contamination. Acknowledging the limitations of the current dataset, EPA has committed to a further evaluation of background concentrations of our COCs at the site as part of pre-design work for OU-1 and remedial investigation activities for OU-4. The ROD includes language that provides for the potential to adjust cleanup levels if this further evaluation of background demonstrates a need to do so. The EIC and the lead State agencies will be invited to participate in review of this evaluation. Depending on findings and the potential magnitude of any such change to cleanup levels, the appropriate modification to this ROD would be made, if needed (memo to file, notice of significant difference, ROD Amendment, etc). It should be noted that the findings regarding background are not expected to meaningfully influence the comparison of cleanup alternatives because: • for residential areas the cleanup selected is the only available option to ensure that the goals to return contaminant levels to those that are naturally occurring, • cleanup levels set to background will be adjusted equally for all alternatives is background estimates change, and This formal cleanup decision's cleanup goals are only for the mine site and residential soils (Operable Unit One). There will be unique cleanup goals developed for the other 39 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary o inappropriately raise the level used to define background or natural levels of contaminants in the area, and o incorrectly define the area's land as contaminated and not needing cleanup. The Elem Tribe is concerned with both: • background, and • off-site soil samples. For background, the Tribe: • identified sampling issues multiple times (including as early as 2020 in stakeholder planning meetings - Strategic Planning Sessions), • accepted EPA's informally agreement with the concern (despite EPA doing anything immediately to revise existing studies, and • communicated this technical concern and others with EPA without the input being incorporated into technical documents and influencing cleanup processes and decisions. For off-site soils, the Tribe is concerned that: • contaminants may have blown offsite with dust, or • flowed off site with water that contact mine waste. parts of the site (Clear Lake - Operable Unit Two and the North Wetlands - Operable Unit Four). An example 2015 study in Texas: • evaluated windblown contaminant transport from an inactive mercury mine, and • found the area 300 meters from the site (called a halo) had mine- related impacts in shallow soil. Commenters stated that while every site has different wind speeds and local conditions, it is logical EPA can use the study (described above) to: • compare to Sulphur Bank conditions, and • indicate if soil and water samples were likely too close to the mine, • confirm if the samples satisfy background sampling guidance, • respond to the Tribe's technical advisor's presentation regarding inaccurate soil samples, and • make adequate changes to: o the background soil study (pre-mining baseline assessment), and o the evaluation of cleanup options (FFS). 4. Mercury Bioavailability Factor, Speciation Data, and Soluable Fraction's Effect on the Human Health Risk Assessment Public Comment EPA Response 40 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Commenters stated that the following are other factors that result in less protective mercury soil cleanup goals. EPA's uses mercury's bioavailability factor, speciation analysis, and the soluable fraction to understand area conditions" impact on peoples" mercury risks. • Bioavailability factor (the rate mercury can become absorbed by plants, animals, or humans) - 10%: If there is a higher bioavailability factor, then EPA's cleanup would be more protective. It is questionable because of two errors: o A 2021 study as a basis for using the factor for soil. The Elem Tribe previously identifies that the citation refers to an arsenic study, not a mercury study, o A past study (the Engineering Evaluation/Cost Analysis for the Northwest Waste Rock Pile as supporting the 10% bioavailability factor. The Tribe can find no independent analysis of mercury study. • Mercury speciation data (the process by which a species evolves and becomes unique with different properties). EPA's data was not sufficient because there was: o a small number of samples (two soil and two sediment samples), and o an unusually wide range of soluble fractions from 0.6% or 52% (percentage or rate that contaminants dissolve in water or solubility). • Soluable fraction (percentage or rate mercury can become accessible to and absorbed by plants, animals, or humans). The wide range of soluable fraction indicates an unclear: o understanding mercury's solubility and affect for those coming - into-contact with it, and o idea of the appropriate cleanup goals should be (the larger the percentage, the greater the potential human health risk, and the higher cleanup goals would be), and o logic for why EPA chose a lower and far less protective percentage than those allowed under Superfund law. Commenters request that EPA should: • address mercury bioavailability, speciation data, and solubility technical concerns, • correct and explain the errors, • improve understanding of mercury, • set more protective cleanup goals, and • explain how the cleanup goals ensure protection of human health and the environment. EPA tried to evaluate the site-specific speciation of mercury for the SBMM site to derive a site-specific mercury bioavailability, but encountered several issues that rendered these data unusable for the HHRA. For this reason, EPA chose to: • acknowledge the data limitations and laboratory issues, and • make a conservative mercury speciation assumption of 10% mercuric chloride to 90% mercuric sulfide. EPA determined this ratio is conservative and protective based on a review of available data, published literature, and the expertise of technical support personnel with pertinent experience. Further data collected following completion of the HHRA at SBMM has reinforced this conclusion. Preliminary data from work performed by the United States Geological Survey in 2023 found that in 20 composite samples of mining waste from across the Site, mercury bioaccessibility in most samples was less than 1%. In response to public comments, EPA: • revisited the Human Health Risk Assessment assumptions regarding exposure scenarios of people encountering site contaminants, • evaluated cumulative risk to ensure that the cleanup levels being selected reflect real-world scenarios, are protective of the community's health and environment, • revaluated the traditional tribal use and the unauthorized tribal user(s) of the mine site separately, • evaluated the results and determined there was a need, accordance with EPA guidance, to revise (lower) cleanup levels to for multiple COCs in the residential areas and on the mine site - see Table 2-3 of the ROD for the revised cleanup levels, where the cleanup will be performed to background, this is denoted with ""(PMB)" following the identified value. 41 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary 5. Sediment Contaminant Level Cleanup Goals Public Comment EPA Response There are similar inadequacies with EPA's background Clear Lake sediment samples. In the study: • Figure 1 shows the sample locations, • all the background samples were collected from the Oaks Arm of Clear Lake, which is also part of the Sulphur Bank Site, • the shallow sample locations have been proved by researchers (from both UC Davis and the Water Board) to have far higher mercury levels than other parts of the lake, and, so, • the samples most certainly were impacted by the mine's contaminants. Commenters stated that other sample ing inadequacies include: • sample locations seem to be chosen with a specific focus (spatially biased distribution), and • an indication of intentional choose of the number of samples (numerically biased) due to the inclusion of contaminated sediments. Researcher Richardson and others reported on the age and mercury levels and types (sediment cores) in Clear Lake, and: • found that in 1927 there was a significant increase of levels, • connected the increase to a mine technique, • acknowledge that the technique likely introduced more mercury, and • concluded that EPA's mercury levels estimates are less than half of the naturally-occuring levels. Commenters requested that EPA should: • collect more sufficient sediment samples, • provide a more accurate analysis of contaminant levels, and • confirm whether high levels are naturally high or not. The Selected Remedy is: • specific to the mine site and residential soils (Operable Unit One), and • does not include the separate cleanup decision document(s) with unique goals developed for Clear Lake (Operable Unit Two) and the North Wetlands (Operable Unit Four). EPA acknowledges the commenter's concern regarding the HHRA's calculated "ambient" sediment concentrations and the limited dataset it was based upon. Establishing a background sediment concentration in Clear Lake will be further evaluated in the OU-2 Remedial Investigation and/or Feasibility Study. This ROD does not address the contaminated sediments in OUs 2 or 4. EPA continues to evaluate how mercury behaves within the Clear Lake system, including the factors that influence mercury's movement through the lake sediments and within the food chain. This effort is being coordinated with the United States Geological Survey and the state's Blue-Ribbon Committee for the Rehabilitation of Clear Lake. An accurate understanding of the nature and extent of soil contamination in Clear Lake will be essential to making well informed decisions on how to manage mercury levels in the lake (including in the fish within the lake). 6. Human Health Risks and Concerns Public Comment EPA Response Commenters stated that in the Human Health Risk Assessment (HHRA) for the mine site and residential soils, EPA: • characterized pre-mining background levels for environmental media, such as soil, sediment, and water, See responses to verbal comment 111(a) and written comments 111(a), III(c), and multiple within IV(a). 42 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary identified levels nearly as high (or in a few cases, higher) than site related levels, established a higher background mercury level than the state, underestimated people" exposure risk, set cleanup goals (according to background) that does not align with the state's mercury sediment level goal to restore Clear Lake, and implies that the mine's waste somehow made environmental media cleaner than it would be naturally. Commenters requested that EPA should: • Considering soil background levels, EPA should report if: o the range of background levels could be statistically different than site impacted ones, o it followed EPA's guidance (Guidance for Comparing Background and Chemical Concentrations in Soil for CERCLA Sites - 2002), and o it conducted a site impact comparison to determine if data is valid or if it invalidates risk calculations. • Considering EPA's acceptance of higher natural background than site related risk, it: o reevaluate the probable underestimation of tribal exposure to mine contaminants, o communicate if its existing study reduces the cleanup levels to the lowest allowed under Superfund law, and o reconsider its claim that tribal consumption of tule stalks, tule roots and cattails had a higher health risk before the mine existed (shown in the "Ambient Tribal Hazards" category in Table 8-12 of the HHRA). • Considering the issue of high background and low risk: o address the fact that it presents environmental justice concerns, o conduct a more defensible analysis, o develop a more accurate understanding of health risks, and o create a legal reason for a more protective cleanup. EPA agrees that the presentation of incremental risk in the 2021 Sitewide Human Health Risk Assessment was inconsistent with EPA guidance. Text of the document had been edited to eliminate incremental risk from the discussion of findings/conclusions, however the key summary table (Table 8-1) retained the presentation of incremental risk erroneously. A Human Health Risk Assessment Errata was prepared for the primary purpose of correcting this inclusion and was finalized in October 2023. This HHRA Errata is included in the administrative record for this ROD. For the cleanup and soil related human health risk: • it should be noted that there is a difference between the assessment of risk in an HHRA and the management of risk that is evaluated in the Feasibility Study and selected in the ROD. • the HHRA's intent is to identify what contaminants of concern (COCs) warrant EPA cleanup action and for which exposure scenarios. • numeric remedial coals (which become cleanup levels) are then back calculated based on the acceptable risk level for the identified COCs for each exposure scenario. A Focused Feasibility Study Errata was prepared and completed in October 2023 in part to better document how the calculation of risk-based target concentrations were performed for the OU-1 FFS, as these were not clear in the original 2021 FFS. • where a calculated risk-based target concentration is found to be below background, the cleanup level is set to background, as CERCLA does not extend EPA authority to remediate below background. This formal cleanup decision's cleanup goals are: • only for the mine site and residential soils (Operable Unit One), and • not for the other parts of the site (Clear Lake - Operable Unit Two and the North Wetlands - Operable Unit Four) that will have unique cleanup goals developed according to updated evaluation of contamination. EPA's plan for human health risk management and related environmental justice concerns will be robust and include: • Cleanup planning based on community concerns. • All required best practices for construction related dust control measures, such as monitoring emissions, application of water to reduce dust generation, and use of appropriate Personal Protective Equipment on site to prevent workplace exposures. • Collaboration with the Elem Indian Colony and the surrounding community on traffic and dust control management. • Coordination with the community about the need for additional air quality monitoring on or nearby the Elem Indian Colony. 43 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary 7. Cleanup Goals for Mine Site Soil and Rock Public Comment EPA Response Commenters stated that EPA's mercury soil cleanup goal is: • roughly 10 times higher than the background estimate, and • about 100 times higher than the University of California's estimate (Figure 2 in Elem Indian Colony comment letter). They also stated that EPA is: • giving tribes false confidence that their people can safely return to normal lifeways, and • developing cleanup goals that are arguably more dangerous than no cleanup at all. Commenters requested that EPA should: • explain EPA's higher background estimate relative to the state's, • establish a mercury cancer or noncancer risk number (carcinogenic or noncarcinogenic risk - hazard index), • understand risks more accurately to develop a protective cleanup standard, and • address concerns that the cleanup will be safe for anticipated future land uses including for Tribes. See responses to prior comments regarding revisions to the selected remedy in response to public comments. Cleanup levels for each remedial component/action area are based upon the Reasonably Anticipated Future Land Use for that area. See Section 2.6 of the ROD for discussion of the RAFLU. For on-mine soils, the calculated mercury cleanup level being addressed by the commenter is appropriate for the future land use of "limited tribal use," which was defined as 2 12-hour days per week spent on-site engaging in tribal practices (with associated exposure factors). This future land use is informed by the fact that the mine site is privately held land owned by a trust and the EIC tribal government indicated they were not interested in the future purchase of the property. For this reason, the future tribal use of the property is assumed to be "limited" due to both the limitations that will be necessary to impose to protect the integrity of the remedy (e.g. digging or vehicular travel across engineered caps could damage them) and because this future land use is presumed to be "unauthorized" for the foreseeable future. EPA's PMB estimate of background was based upon the data analyzed in the PMB Tech Memo (2021). This document is summarized in section 2.5.3.4 of the ROD. 8. Cleanup Goals' Compliance with Clear Lake Mercury Level Limit Entering Clear Lake with Water Law Public Comment EPA Response Commenters stated that mine contaminants are transported into Clear Lake with water, dust, or other means. Mercury's cleanup goal: • is one of the most important means to substantially reduce mercury entering the lake, and • is greatly influenced by water: o flowing across the site that contacts mine waste, becomes more contaminated and acidic (acid mine drainage) o filling the open mine pit called Herman Impoundment, o moving with shallow groundwater, and o picking up more contamination and entering the lake through the Waste Rock Dam (a structure of earth that separates the lake from the mine site). The State of California requires the development of plans to manage watersheds in a manner that supports environmentally and economically healthy watersheds that benefits the community and are sustainable for future generations. The Basin Plan that include Clear Lake contains a Total Maximum Daily Load requirement for mercury due to the existing impairment of Clear Lake with mercury. This TMDL specifically identifies the SBMM as the primary source of mercury into the lake and sets the indicated 0.5 kg/yr target for groundwater-related contributions of mercury from the mine to Clear Lake. EPA's selected remedy takes a straightforward approach to remediating the loading of mercury from the mine to Clear Lake via groundwater. By removing the waste materials that comes into contact with groundwater and capping the remainder of the 44 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary They stated that EPA's proposed adoption of the state's TMDL for mercury flux at 0.5 kg/year does not mention or include the TMDL's other require of a 95% reduction in mercury inputs from the mine to Clear Lake requirement, nor provide evidence to support the conclusion that the cleanup will meet the 0.5 kg/year target. Commenters requested that EPA: • evaluate the available data and reasonable predictions about site conditions, • determine the cleanup's success. For example, considering the impoundment, EPA can determine whether the cleanup will: o result in levels of mercury entering the lake (post-remedy flux) that will probably be higher than 0.5 kg/yr, o reduce the overall mercury flux by 95%, and o not perform a cleanup that will probably fail (unless there are no other options available), • explain why the cleanup may not achieve the state's mercury levels entering Clear Lake law (TMDL ARAR), and • ensure compliance with state law and the restoration of Clear Lake. Commenters stated that over the years, there have been different estimates of groundwater flow through the Waste Rock Dam from stakeholders. The recommended cleanup includes digging up (excavation) of a portion of Waste Rock Dam (earth structure separating the site and Clear Lake). EPA and the Elem Tribe do not agree on the cleanup's impact. EPA claims it will: • control the water leaving the open mine pit (Herman Impoundment), • prevent its contact with contamination in the dam, and • reduce the release of site contamination into Clear Lake. They also stated that according to the Elem tribe, EPA's groundwater claim is simply inaccurate because: • impoundment water will still contain mercury that can be released after the cleanup, • there may be unmeasurable releases from other sources like ground and surface water, and windblown dust, and • EPA generalizes that the impoundment's higher elevation means that the main natural flow of groundwater is toward the Lake (the Tribe agrees, and emphasizes, at some parts of the site, the change in elevation and slope more significantly controls flow). waste, EPA is cutting off the pathways by which water would accumulate mercury and transport it to Clear Lake. A geochemical mixing model for Herman Impoundment (CH2M, 2016) concluded that once the exposed waste piles surrounding the impoundment are capped, the concentrations of mercury in the impoundment will be sufficiently low that, if this water is prevented from interacting with waste on its way to Clear Lake, the TMDL will be met. Further, by capping the waste surrounding Herman Impoundment and redirecting the clean stormwater that falls on the site to Clear Lake, rather than allowing it to flow into Herman Impoundment, the water level in the impoundment will be reduced, further reducing the movement of groundwater from the site to Clear Lake. Regarding the 95% reduction element of the TMDL, EPA consulted with the Central Valley Regional Waterboard and determined this to be an unrealistically vague requirement. It was not clear what the Board's intended point of reference for this reduction was and therefore it would not be possible to determine when this reduction requirement was met. For these reasons, the 0.5 kg/year total flux via groundwater target included in the TMDL was set as a performance target for the Selected Remedy. Remedial Action Objective 5 specifically addresses the flux of mercury from the mine to Clear Lake via groundwater. This RAO is a commitment in the ROD and therefore failure to meet the specified 0.5 kg/year limit would constitute remedy failure and thereby additional evaluation and potential action by EPA to redress the problem. Accordingly, the flux of mercury from the SBMM site to Clear Lake will be closely monitored and evaluated during pre-design, design, remedy implementation, remedy effectiveness evaluation(s), and in operations and maintenance following the remedial action. Pre-Design investigation of the mercury flux is already underway and will help EPA to further refine estimates of flux and how the selected remedy for the WRD will be applied to provide compliance with RAO 5. In consultation with the Elem Indian Colony, EPA has included several additional provisions in the Selected Remedy that are intended to provide greater assurance of the effectiveness of the remedy and/or specific targets for evaluation of further action if monitoring suggests remedial success is unlikely or is not happening rapidly. These can be found in section 2.12 of the ROD. 45 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Commenters requested that EPA should: • consider that the Tribe's cleanup option (Alternative 8) and its containment of groundwater will eliminate the flow of mercury into Clear Lake, • estimate the post cleanup mercury flow by considering two variables after the cleanup: o the average of groundwater flow through the Waste Rock Dam; and o the average concentration of mercury in Herman Impoundment water, • explain the different understandings of ground water (including between EPA, USGS, the state, and UC Davis), • consider other estimates in flow analysis, • provide clear assessments of why or why not other studies may be applicable, and • ensure analysis gathers important new information and not just indicates expected conditions. Commenters stated that if one of the following actions above does not happen, then EPA's recommended cleanup will not meet the state's mercury level allowed to enter Clear Lake each year. • Herman Impoundment water (the water flow through the Waste Risk Dam) mercury level goes above 2.38 micrograms per gallon. • The groundwater flow rate is higher than 400 GPM. • The reactions picking up contamination (including mercury) in the dam are not completely stopped. Commenters requested that EPA should: • take additional steps to reduce groundwater flow into the lake, and • ensure the cleanup complies with state law. Commenters stated that based on the following, it appears that the cleanup will not comply with state law limiting site mercury levels entering Clear Lake: • Mercury levels in the natural spring water (hydrothermal water) entering the impoundment. • EPA's use of natural mercury flow to justify higher site contributions of mercury that match the hydrothermal levels. 46 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary Commenters requested that EPA should: • evaluate if the mercury flow through the Waste Rock Dam is much higher than its assumption, • consider groundwater influences from other areas or other depths, or soil erosion, and • address the history that if there was no mine, there would be no Herman Impoundment or Waste Rock Dam, and there would be less natural water flow and lower mercury level, • explain why the cleanup goals are below he state's first mercury level requirement for Sulphur Bank, • provide stakeholders an explanation for incompliance with state law • explain the different mercury reduction estimates from the state, • resolve differences before the formal cleanup decision and ensure compliance with state law. 9. Compliance with State Law for Site Surface Water Public Comment EPA Response Commenters stated that stakeholders have continued to disagree about the need for the site's groundwater management. They also stated that EPA believes its cleanup can: • reduce mercury flux to Clear Lake, • allow site groundwater to continue flowing into the lake, and • achieve reductions to satisfy cleanup goals for the lake. The Tribe believes: • EPA's recommended cleanup is not likely to comply with requirements and is not tested, and • the most reliable way to prevent the release of the site's mercury is by pumping and treating site groundwater. Commenters explained that earlier in the Superfund cleanup process, EPA: • supported containing site groundwater, • evaluated pumping of Herman Impoundment groundwater (and even filling it with waste), • received the state's support for the pump and treat approach (in 2004), and • proposed long-term pumping and treating impoundment water (in 2006). Then: Please see response to written comment 111(a) above. As noted, adjustments were made to the Selected Remedy in response to State, Tribal and community comments. Additional provisions help assure that the Selected Remedy will meet the mercury flux requirement of the TMDL in a prompt manner and specific triggers were included should this not occur. See ROD Section 2.12 under the heading of "Waste Rock Dam Excavation and Capping". The scope of the selected remedy does not include the groundwater media, therefore many of these comments fall beyond the scope of this decision document. Ongoing data collection will inform the potential scope of any necessary remedial action for OU-1 groundwater. OU-1 groundwater will be included in a future decision document for the site. EPA is coordinating closely with the state's Central Valley Water Quality Control Board and the Department of Toxic Substances Control regarding the required water quality protections for the selected remedy. The selected remedy will see exposed waste on site capped and clean stormwater diversion systems installed, including reconstruction/improvements to the existing stormwater infrastructure where it is found to be inadequate to ensure stormwater discharges are free for mining-influenced waters. These components of the selected remedy address the commenter's concerns regarding release of site-influenced stormwater to Clear Lake. 47 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • the state advocated for a cleanup that had lower operation and maintenance costs, and • EPA abandoned the pump and treat approach (in or around 2011). (The Elem Tribe believes that groundwater containment is a better, more certain option). Commenters requested that EPA should: • address the Tribe's concerns, • explain the decision to remove the pump and treat option, • reincorporate it into the recommended cleanup plan as a backup option, • effectively evaluate it's potential to remove the lake's fish consumption advisory recommendations, • consider the overwhelming community interest in restoring Clear Lake, • better understand the groundwater flow through the Waste Rock Dam, • assure stakeholders and the affected community of the current cleanup's compliance with state law, • ensure the cleanup is most protective of the community and environment, • avoid being strongly driven by strong state opposition, based on lowering future O&M costs, and • respond to the state's other reason that EPA's pump and treat option relied on an outdated understanding of groundwater. Commenters stated that EPA should not be discharging untreated storm water into Clear Lake. The discharges are regulated by the State Water Resources Control Board's general NPDES permit (Order No. 91- 13-DWQ, General Permit No. CAS000001). Commenters requested that EPA should: • consider the discharge of storm water into surface waters, directly or through the storm water system (but do not consider construction activities), • comply with the law prohibiting discharges of contaminants that cause pollution or nuisance (Section 13050 of the Water Code, and • recognize that stormwater discharges from sources like uncontaminated natural springs are allowed. Commenters stated that EPA's evaluation of cleanup options: 48 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • describes the possible use of limestone gravel in the Waste Rock Dam's water flow (a natural treatment option for pH control that may reduce water acidity and contaminant levels entering the lake), • considers the potential discharge through the dam called point source by the regulations, and • recommends a cleanup option that would not be allowed by law for an impaired water body like Clear Lake anyway. They also stated that EPA's recommended cleanup includes: • diversion of clean stormwater from Herman Impoundment and into Clear Lake, • an inaccurate description of surface water quality and claim that Herman Impoundment's water quality will improve, and • insufficient claims that water quality is improving from stormwater management, o stormwater somehow becomes clean before reaching the lake, and it is reasoning to allow site water discharge without treatment. Commenters request that EPA should: • account for water monitoring reports documenting contaminated site water (acid mine drainage) impacts, • consider the acidic surface water pH measurements (as low as 3.5) and high mercury levels (up to 2.4 pg/L), • include understanding that the surface water is not consistently "clean," • assess surface water discharges into Clear Lake influence, and • comply with the state mercury level limit law. 10. Failure to Comply with California Mine Waste Management Regulations Public Comment EPA Response Commenters stated that EPA's recommended cleanup will not comply with California's mining waste regulations for waste classification. (27 CCR §22470-22510). Commenters request that EPA should: • appropriately classify site wastes, • correct analysis of wastewater quality risk, and • reinterpret and explain state laws allowing for waste classification justifications. EPA acknowledges the commenter's concern about CA Title 27 compliance. EPA coordinated very closely with the state's Department of Toxic Substances Control and Central Valley Water Quality Control Board regarding the Applicable or Relevant and Appropriate Requirements (ARARs) for the selected remedy. Upon discussion of the State's ARARs for this remedy, neither EPA's legal counsel nor the counsel for either lead State agency found that the selected remedy would violate any State ARAR, including CA Title 27. See Table A-l for a complete presentation of the ARARs and their impact on the remedy. 49 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary During remedy design, EPA will perform sampling of the waste on site for classification under Title 27 into waste groups A, B or C. Group A Wastes are expected to be capped with a full HDPE-lined, RCRA-type cap, while Group B Wastes may be capped with a RCRA-type cap or an engineered alternative such as an ET cover. 11. Other Technical Issues of Substantial Concern i. Possible Ground Water Flow into Clear Lake from Locations other than the Waste Rock Dam ii. No Numerical Cleanup Goals for Ground Water iii. No pH Cleanup Goals iv. No Mercury Flow Monitoring System v. Cleaning Up Parts of the Waste Rock Dam in Place vi. Mine Site and Residential Soils" Cleanup Connection to Clear Lake vii. Herman Impoundment's Mine Waste viii. Possible Contamination Underneath Mine Waste Piles ix. Sources of Mine Waste Contamination x. Recommended Cleanup Glossary of Terms xi. Selection of EPA's Recommended Cleanup Possible Groundwater Flow into Clear Lake from Locations Other Than the Waste Rock Dam Public Comment EPA Response Commenters state that for the site it is important to understand the flow of groundwater and containment releases into Clear Lake. They requested that EPA should: • evaluate recent groundwater monitoring reports (EPA is significantly behind in publishing the site's groundwater monitoring reports with the most recent from 2017), • consider contaminated groundwater flow from anywhere else other than the Waste Rock Dam, • assess the previous back-up cleanup option (contingency plan) that controlled shallow groundwater on the north side of the site (it is no longer included in the current plan, and instead, will not be considered until another part of the site's future evaluation of cleanup options), • respond to EPA's and the state's different identification of Waste Rock Dam groundwater flow, and • evaluate other potential sources of mercury (including from Northwest Rock Pile southwest flow under the Elem Indian Colony and into the lake's wetlands - shown in the 2016-2017 groundwater monitoring report maps). EPA acknowledges the commenter's concern. Stormwater and groundwater monitoring reports are available in the administrative record reporting data up through the winter of 2020-2021. Reports up through 2019 were available at the time of the Proposed Plan release. Based upon multiple lines of evidence, EPA has determined that the primary pathway for movement of contaminated ground water from the mine site to Clear Lake is through the Waste Rock Dam. This does not preclude the possibility of groundwater- related releases of mercury and other COCs from other parts of the site, however potentiometric groundwater elevation maps collected over decades of groundwater monitoring suggest that there are fairly strong groundwater gradients pointing towards Herman Impoundment in the areas nearest the impoundment and towards the North Wetlands in the areas on the northern edge of the mine site. EPA's OU4 data suggests that the North Wetlands is a perpetual (or near perpetual) groundwater sink, meaning that it evaporates more groundwater than it receives and thus is not expected to provide a pathway for groundwater related releases from OU-1 to reach Clear Lake. This conclusion is based upon currently available data and will be further evaluated as part of the OU-4 CERCLA process. On the far southwestern corner of the site, the groundwater gradients suggest that there may be flow from areas containing mining waste towards Clear Lake, however 50 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary monitoring data from wells near the Clear Lake shoreline in this area do not show significantly elevated mercury concentrations (see the Annual Groundwater Monitoring Reports 2012 through 2021). To the extent that groundwater flow in this area contributes mercury to Clear Lake, it would be subject to RAO 5, limiting the annual load of mercury via groundwater entering Clear Lake to no more than 0.5 kg/year. ii. No Numerical Cleanup Goals for Groundwater Public Comment EPA Response Commenters stated that the state of California: • classifies most groundwater aquifers with potential public use, and • requires those waters to be maintained "to the maximum extent possible" (non-degradation policy). They also stated that EPA has decided that the site's groundwater: • naturally has poor quality, • does not have public beneficial uses (such as for agricultural or other municipal reasons including for drinking), and therefore, • its cleanup does not have to comply with state law, and instead, will only be monitored. Commenters explained that EPA's cleanup: • describes a cleanup goal of protecting "existing and future beneficial uses of on-site groundwater," • does not evaluate of all options to cleanup and contain groundwater including by pumping, • does not sufficiently consider the Elem Tribe's favored option to pump and treat the water, and • does not include analysis of past groundwater reports indicating the water may be useful for the public (Columbia Geosciences 1988 report that found mercury levels well below the detection limit of 0.2 kg/L). Commenters state that in EPA's 2021 evaluation of cleanup options (Focused Feasibility Study Report) included all the following groundwater cleanup goals. However, EPA's recommended cleanup plan only included the first goal without explanation. • Mercury annual load - 0.5 kg/year (into Clear Lake) • Mercury flow rate - 0.002 milligrams per liter (into the lake) • Iron - 0.3 mg/L (into the lake) • Sulfate flow rate - 250 mg/L (into the lake) • Aluminum flow rate - 0.05 mg/L to 0.2 mg/L (into the lake) ROD Section 2.5.3.1 and 2.6.3 present summary of the existing information regarding groundwater at the site. There are no current users of the groundwater underlying the SBMM mine site. This water is heavily influenced by naturally occuring geothermal constituents. State Water Resources Control Board Resolution No. 88-63 provides for an exception to the default drinking water beneficial use for groundwater where total dissolved solids concentrations exceed 3,000 mg/L. According to the evaluation of background geothermal groundwater quality at the SBMM site, the natural groundwater underlying the site exceeds this threshold. However, until the drinking water beneficial use is de-designated by a Basin Plan amendment, the beneficial use assumption remains in force. EPA is not selecting a groundwater remedy as part of this remedial decision. EPA will continue to monitor groundwater to assess the effect of the selected source control actions on groundwater and will evaluate what further action may be needed to ensure protectiveness and compliance with ARARs. The revised groundwater cleanup levels are in accordance with the scope of the remedial decision EPA is making in this ROD. EPA is not selecting a remedy for the groundwater media. The TMDL will be achieved by removal of source material contributing mercury to ongoing groundwater flow. To the extent that there may be separate groundwater units that require remediation 51 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary They request that EPA should reconsider the conclusion that the site's groundwater has naturally poor water quality (as opposed to having become contaminated by mine-related activities). iii. No Water pH Cleanup Goals Public Comment EPA Response Commenters requested that EPA should: • follow state laws for acidity or pH standards, • consider the national drinking water standards call for pH to be maintained between 6.5 and 8.5, and • include an explanation in the recommended cleanup plan of why or why not these standards are met. EPA has coordinated extensively with key stakeholders concerning applicable or relevant and appropriate requirements (ARARs). EPA explored potential ARARs that might impose a pH requirement on the Selected Remedy. Working closely with the Regional Water Board, EPA determined that no such pH requirement exists. iv. No System for Monitoring Mercury Flow Public Comment EPA Response Commenters stated that EPA does not: • have a reliable method for understanding and monitoring mercury flux levels into Clear Lake, nor • appear capable of determining whether the cleanup complies with state law regulating the mercury levels entering the lake. They also stated that EPA: • acknowledged the mercury flux level uncertainty, • installed new groundwater wells and improved monitoring in 2022,and • informed the Tribe on several occasions that many of the new wells are did not find water and dry, thus do not work. Commenters requested that: • explain mercury will be monitored in surface water, windblown dust, erosion, nor via groundwater by any pathway other than the Waste Rock Dam, • address serious impacts for its understanding of site conditions and how mercury leave the site (EPA's Conceptual Site Model), and • identify a process to measure all mercury flux pathways from the site into the lake, and • ensure the cleanup is effective. EPA acknowledges this concern regarding accurate monitoring of the movement of mercury from the site to Clear Lake. EPA has coordinated extensively with key stakeholders on this matter. EPA continues to evaluate the flux of mercury from the OU1 to OU2 and is incorporating additional groundwater monitoring data and advanced modeling techniques into ongoing work on this subject. The baseline conditions this work provides will be used to inform the remedial design, remedy implementation and remedial action effectiveness monitoring. The results of this study will be made available to the key site stakeholders, including the EIC, and the public once it is available. Mercury releases via surface water, windblown dust, and erosion will all be addressed by the capping of the exposed waste piles (source areas). Once capped, these piles will not generate site-influenced stormwater, fugitive dust emissions, or have the potential to erode directly into Clear Lake. Mercury loading via groundwater pathways outside the WRD warrant additional evaluation during remedial design and may inform remedy implementation. v. Cleaning Up Parts of the Waste Rock Dam in Place Public Comment EPA Response 52 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary California's waste management laws require a minimum 5-foot distance between the highest groundwater levels and the bottom of the mining waste unless they have: • a bottom liner (effective separation tool between at the bottom of the waste), • leachate monitoring and collection system (management of contaminant levels in water leaving the waste), or • impermeable cap (a cover for the mine waste that water cannot pass through). According to EPA's recommended cleanup plan, part of the Waste Rock Dam will: • remain in place with an impermeable cap, but • not a bottom liner nor a leachate monitoring and collection system (described above), and • need to have at least a 5- foot separation between the bottom of the waste and the highest groundwater level (according to state regulations). Commenters requested that EPA should: • document the 5-foot separation requirement, • evaluate if there is a way to reduce groundwater flow through the dam (where mine waste will be removed and the area will be filled with clean material), • provide reasoning for why the cleanup does not have to comply with the waste management law, and • explain why parts of the dam do not have to comply. Commenters state that in 2019, EPA: • planned to relocate the mine waste from the Northwest Waste Rock Pile into the Northwest Pit, • agreed to evaluate the inclusion of a 5-foot base, • met objection from the state Department of Toxic Substances Control (in part because of heated ground water and gas activity that still could contact the waste and release contamination), and • temporarily abandoned the relocation and 5-foot bas option because federal and state officials could not agree on its adequacy of the plan. These same problems may continue and make EPA's current plan for the Waste Rock Dam not possible. EPA has coordinated extensively with key stakeholders on this matter. In evaluating ARARs for the Selected Remedy, EPA and the Regional Water Quality Control Board determined that California Title 27 does not require that existing mining waste piles that will be capped in place to be sited 5 feet above the highest expected groundwater levels. 53 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary vi. Mine Site Cleanup's Connection to Clear Lake's Cleanup Public Comment EPA Response Commenters request that EPA should: • explain the cleanup approach for the whole site, • do not ignore the connection between the mine site and Clear Lake, and • address negative future impacts of the cleanup for the lake (like the potential need for dredging lake sediments (digging up contaminated material at the bottom of the lake that logically would need to be disposed of on the mine site). EPA acknowledges the comments. This ROD focuses on OU-1. A comprehensive remedial strategy for the site cannot be articulated because feasibility studies for OUs 2 and 4 have not yet been developed and therefore any presumption of what these remedies would entail would be both pre-decisional and not well informed. EPA will continue to coordinate with key stakeholders and provide the community with information about current and future work for other OUs. For more information, please visit the site's webpage: www. epa. eov/superfiind/sulphurbankmercurv vii. Herman Impoundment's Mine Waste Public Comment EPA Response Commenters stated that EPA's recommended cleanup plan does not acknowledge that there are an estimated 50,000 to 200,000 cubic yards of contaminated sediments in Herman Impoundment. This material consists of a combination of: • wastes placed in Herman Impoundment during EPA's 1992 cleanup, • erosion of mining wastes from slopes next to the pit, • and contaminants from the hot springs entering the pit. They also stated that according to the evaluation of cleanup options, EPA: • plans to leave the material in place. • May need to follow the 5-foot waste separation requirement (or need to waive the requirement), and • Does not confront the concerns and instead defers it to after the formal cleanup decision. Commenters requested that EPA should: • justify the deferral of an important decision that is inconsistent with its rejection of Elem's Alternatives 8 and 8A (in part because adding mine waste to the impoundment would make require the same 5-foot separation), and EPA acknowledges the comment. In response to this comment EPA has evaluated whether the mine waste that was placed in the northwest corner of Herman Impoundment may need to be removed as part of the selected remedy and has determined that if this material is saturated with Herman Impoundment water, it may need to be excavated and relocated. The question of how much material may need to be excavated and where it would be consolidated to will be evaluated during remedial design. It was determined that this requirement would apply evenly across all action alternatives and therefore does not affect the comparison of alternatives and thus this remedy selection. 54 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary • explain why non-compliance is manageable for EPA's option and not for the Tribe's (that is immediately disqualified). viii. Possible Contamination Under Mine Waste Piles Public Comment EPA Response Commenters stated that the recommended cleanup's planning investigations will include a digging a number small, deep holes called soil borings. They will be used to sample soil and groundwater under waste piles. This is a long-overdue task. The Tribe has warned that: • rainwater flowing into the piles may release contaminants, • contaminants could be inactive and held in the native soils with risk of future release, and • putting of the investigation means that the cleanup will not have the ability to deal with the contamination (if it is found). Commenters requested that if there are unexpected finding in the planning investigations that make the cleanup ineffective, then presumably, EPA should: • withdraw the Proposed Plan, • defer the Record of Decision, start over, and • consider the significant delay of the cleanup. EPA acknowledges this comment. Should pre-design or design investigations come to findings significantly differing from EPA's current understanding of the contaminants and their fate and transport processes (called the conceptual site model), EPA will need to evaluate the extent to which any such findings have bearing on the selected remedy. If determined necessary by EPA, there are modification and amendment processes to make adjustments to the ROD. ix. Source of Mine Waste Contamination Public Comment EPA Response Commenters stated that EPA incorrectly states that all the mine site wastes cannot be reliable contained. In EPA's explanation of the waste source materials, it states that: • they are highly toxic or highly mobile and, in general, cannot be reliably contained, • then EPA states that all mine site source materials are principal threat waste that cannot be reliably contained, and none are low level threat waste, and • the cleanup options that include on-site consolidation and capping of mine waste are containment technologies for managing waste. Commenters request that EPA should: • explain the contradiction of the containment technologies and the statement that all wastes cannot be reliably contained, and • revise the text to remove the discrepancy. The Proposed Plan contained language that was reevaluated prior to the development of the ROD. ROD Section 2.11 presents the "Principal Threat Waste" determination for this remedy, which includes consideration of the toxicity, mobility and ability to contain contaminants at the site. In this Section, EPA finds that the solid media, including mine waste and contaminated soil addressed by this remedy are not highly mobile and can be reliably contained in most cases. The exception to this is the saturated waste within the Waste Rock Dam, which is considered principal threat waste because it is an on-going source of mercury release to Clear Lake. 55 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary x. Recommended Cleanup Plan Glossary of Terms Public Comment EPA Response Commenters stated that Geosynthetic Clay liner (GCL) is incorrectly defined in the Glossary of Terms. The text defines a GCL as "a water- proof capping material that uses sodium bentonite clay to form a hydraulic barrier'. GCLs: • function as a barrier by absorbing water and swelling to further reduce permeability, • likely cannot be considered waterproof, • not only include sodium bentonite clay, the most used material in GCLs," • use other materials/clays to form a hydraulic barrier, and • are used as liners in addition to capping. EPA acknowledges the technical clarification and input. Commenters request that EPA should: • Revise the GCL definition to include the description (above). xi. Selection of EPA's Recommended Cleanup Public Comment EPA Response Commenters stated that EPA's recommended cleanup plan: • states it has selected the best elements of several options' strengths and weaknesses, but • seems to be the fastest and cheapest option for the cleanup. Commenters requested that EPA should: • consider that complete excavation and off-site disposal of all site contamination sources (SA Alternative 4), and • evaluate if it would be the best plan for the environment and the surrounding community (even if it costs $808.1 million). Commenters stated that in the description of SA Alternative 4 EPA states that the option: • results in the permanent removal of the site's contamination source area risks, and • includes substantial impacts to infrastructure and public welfare associated with waste hauling. This screams that the surrounding communities' welfare impact has little regard in the decision. Please see comment response above such as written comment response 111(b). EPA guidance sets a high bar for offsite disposal for a range of reasons, including the fact that off-site disposal of CERCLA waste runs the risk of moving a contamination problem from one community to another. The "Off-Site Rule" describes the circumstances under which CERCLA waste can be disposed of off-site as part of a Superfund site cleanup. This rule is defined in 40 CFR 300.440. Additional information about the Off-Site Rule can be found at httos://www.eDa.20v/suDerfiind/site-rule . Sections 2.9 and 2.10 of the ROD present the alternatives analysis and comparison of alternatives wherein the offsite disposal alternatives are evaluated. While off-site disposal of site waste was found to be potentially effective and compliant with ARARs, it ranked poorly on several of the balancing criteria, including cost, wherein it was found to be approximately ten times more costly than capping waste in-place for the same endpoint regarding effectiveness/protectiveness. 56 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary They also stated that in the alternative or option comparison table, there seems to be an inaccuracy between to options. (1) SA Alternative 4's implementability is listed as medium. (2) SA Alternative 3's implementability is listed as low because of the large volume of clean soil that would need to be trucked to the site. If on-site sources of soils are found, it would be medium. Commenters requested that EPA should: • Explain why the SA 3 ranking is low to truck dirt in, and the SA 4 ranking low to truck dirt out. The recommended cleanup is a combination of SA Alternatives 2 and 3. Commenters requested that EPA should: • include SA Alternative 4 in the cleanup, • consider that parts of the site that can be excavated completely with off-site disposal, and • avoid putting more waste on waste and capping it. c. Economics and the Superfund Job Training Initiative Public Comment EPA Response Commenters requested that EPA should consider: • An outreach program for local businesses involving them with site activities and increasing understanding of the cleanup. • High priority placement on the selection of contractors/subcontractors who have included local sourcing of goods, workers, and services. • Advertisements for local subcontractors in local publications. • Purchase/rental of local goods and services (clean soil, construction materials, fuel, trucks, portable toilets, on-site water). • Local job training programs. • Employing interested and qualified members of the Elem Tribe. • Local hiring such as traffic control, truck drivers, laborers. EPA acknowledges this comment and is recognizes the economic opportunities that can be created by major remedial projects such as the SBMM OU-1 remedial action. EPA's contractor must go through a competitive bidding and selection process in accordance with Federal Acquisition Regulations (FAR). Appropriately qualified contractors will have the opportunity to bid on various elements of the remedial action in accordance with FAR requirements. At other Superfund sites, EPA has found that remedial contractors often use local subcontractors because local contractors are less costly than those that need to travel to the site to perform work and may have experience and expertise in the local area that contributes to their qualification. EPA has a program called the Superfund Job Training Initiative, and we plan to utilize so local people can be trained to do construction-oriented work. EPA is: • supportive of expanding the job training initiative, • is generally focused on providing training and qualifications for graduates to be eligible for cleanup positions, and • advised that the entry level jobs are generally more available and so their qualifications should be the focus of the program. 57 ------- Sulphur Bank Mercury Mine Operable Unit 1 Record of Decision - Appendix B: Responsiveness Summary d. Timeline and Other Operable Units Public Comment EPA Response Commenters requested that EPA should: • Consider the use of acceptably tested dredged material from the Clear Lake Oaks Keys channels. • Discuss use of the dredged material with Elem representatives. • Advise local organizations like the CLO Keys POA or Redbud Audubon Society (or myself) of next steps. • Share the Elem Tribal government preferred cleanup option. • Explain if cleanup options could facilitate the purchase or transfer to the Lake County Land Trust. EPA acknowledges the comments and input. As noted in the response to written comment 11(b), EPA expects to evaluate the use of dredge sediments as a possible capping material. The tribe's preferred alternatives 8 and 8A are presented in the 2021 Focused Feasibility Study available in the Administrative Record for this decision document on EPA's SBMM site webpage. The focus of this ROD is the source materials within OU-1. The acquisition of new lands is not within the scope of this remedy. EPA will continue to provide information about work progress towards the implementation of this remedy and progress on other OUs. For more information, please visit: www.epa.aov/suDerfund/sulDhurbankmercurv 58 ------- |