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Home My WebLink About12-20-22 Correspondence - DEQ - Bozeman Solvent Site 2022 Newsletter D E Montana Department of Environmental Quality Bozeman Solvent Site 2022 Newsletter What is the Bozeman Solvent Site? The Bozeman Solvent Site (BSS) is a State Superfund facility undergoing cleanup pursuant to the Comprehensive Environmental Cleanup and Responsibility Act (CECRA), §§ 75-10-701 through -752, Montana Code Annotated (MCA). The BSS includes the former. Buttrey's Shopping Center (Shopping Center) and extends north of the East Gallatin River. In August 2011, the Montana Department of Environmental Quality (DEQ) issued the Record of Decision (ROD) which selected the final remedy to clean up groundwater, saturated soils, and soil vapors contaminated with tetrachloroethene (PCE) and other chemicals. The final BSS cleanup identified in the ROD includes: • Controlled groundwater area (CGWA) • Land use controls at the Shopping Center • Sub-slab soil vapor extraction system (SVE) for soil vapors at the Shopping Center • Enhanced bioremediation (EB) for residual source area saturated soils and groundwater at the Shopping Center • Monitored natural attenuation (MNA) for off-site groundwater • Connection to city water or replacement wells for contaminated drinking water wells. Who is responsible for the cleanup at the BSS? The City of Bozeman (COB) and CVS Pharmacy (CVS) are responsible for implementing the cleanup of the BSS. What is a CGWA? The BSS CGWA was established under an Order issued by the Montana Department of Natural Resources and Conservation (DNRC). The Order established a permitting process for the installation of groundwater wells within the BSS to prevent exposure to PCE contaminated groundwater and to mitigate movement of PCE contaminated groundwater into areas not contaminated. Information on the BSS CGWA can be found here: http://dnrc.mt.gov/divisions/water/water-rights/controlled-ground-water- areas/bozeman-solvent-site. What are the land use controls at the Shopping Center? Land use controls at the Shopping Center are on file at the Gallatin County Clerk and Recorder's office and limit usage to commercial use (e.g., no residential use), and prevent construction where active remediation is occurring. How does the SVE system work? The SVE system removes PCE contaminated soil vapors from beneath the eastern leg of the Shopping Center building. The removal of these vapors reduces the potential for contamination to move upward and impact indoor air in the Shopping Center building. The vapors are treated prior to discharge to the atmosphere. ( I - t Granulated activated carbon drums to treat vapors inside SVE shed at Shopping Center. How does EB work? An organic substrate was delivered through injection wells to groundwater in the residual PCE source area at the Shopping Center property. The organic substrate stimulates microbial growth and creates anaerobic (e.g., low oxygen) conditions. The low oxygen conditions help break down the PCE. Bozeman Solvent Site PCE Concentration Shallow Wells(2014-2022) Enhanced Bioremediation Implementated in 2014 610 ssa soo , 93 rt EBM-3A ]00 BERM-SA + �.EBM�A e3 3V1 �M-l6 t 1.119 n3N CAI-l] — Pnas 2M i Aso I ( 100 0 Date 2 1W What is MNA? MNA relies on natural processes to breakdown and attenuate PCE contamination and achieve site-specific cleanup objectives within a reasonable time. MNA is used in conjunction with source control (e.g., EB) and long-term performance groundwater monitoring. currently use a groundwater well for domestic purposes (e.g_, drinking). How do I know the water is safe to drink? The federal drinking water standard for PCE is 5 micrograms per liter (Ng/L).Groundwater wells that are currently used for domestic purposes within the BSS are sampled annually and analyzed for PCE. No one using drinking water wells within the BSS has PCE at or exceeding the federal drinking water standard. What happens if my domestic well has PCE greater than the federal drinking water standard? If PCE in a drinking water well within the BSS exceeds the federal drinking water standard and the exceedance is confirmed by a second sample, permanent alternate water will be provided by the COB/CVS. If the drinking water well is within the BSS and in an area where COB water services are available, the COB will connect the user to COB water. DEQ will require the well be disconnected from domestic use, but the well water can still be used for irrigation. DEQ may require the well not be abandoned so the well can be used as a performance monitoring point. If the drinking water well is within the BSS and not in an area where COB water services are available, the COB/CVS will install a deeper replacement drinking water well into an area where groundwater is not contaminated. DEQ will require the old well be disconnected from domestic use, but the old well water can still be used for irrigation. The new well will be added to the performance monitoring program. DEQ may require the old well not be abandoned so it can be used as a performance monitoring point. What permits special requirements do I need to comply with to develop rebuild a property in the BSS? If construction activities are adjacent to or just north of the Shopping Center building, fresh air ventilation is required for workers in excavations of certain sizes. The COB is responsible for enforcing this permit. The Trench/Excavation Ventilation permit form can be found at https://www.bozeman.net/departments/transportation- engineering/engineering. A construction dewatering general permit (CDGP) is required for all construction activities that require dewatering. The DEQ Water Protection Bureau (WPB) regulates the CDGP. If a construction site is within the BSS and requires a CDGP, the WPB will coordinate with the DEQ State Superfund Unit (SSU) to determine if sampling for PCE in the dewatering discharge is required. If PCE sampling is required, SSU requires the CDGP applicant to submit a work plan describing the sampling. More information on the CDGP can be found at https://deq.mt.gov/water/assistance. 3 i Additionally, for any remedial action proposed by a third party within the BSS, a work plan must be submitted to and approved by DEQ prior to such work commencing pursuant to § 75-10-711(9), MCA, and Administrative Rule of Montana (ARM) 17.55.110. A third party is anyone other than the COB and CVS as they are subject to the BSS Administrative Order on Consent. Remedial action is defined by § 75-10-701(20), MCA, and includes "all notification, investigation, administration, monitoring, cleanup, restoration, mitigation, abatement, removal, replacement, acquisition, enforcement, legal action, health studies, feasibility studies, and other actions necessary or appropriate to respond to a release or threatened release". More information on the work plan requirements can be found at https://ruies.mt.gov/gateway/RuIeNo.asp? RN=17%2E55%2E110. What is currently happening at BSS? • Continued operation and monitoring (O&M) of the SVE to capture and treat vapors Short-term O&M of a temporary SVE system while waiting for part replacement • Continued groundwater monitoring to evaluate the EB and MNA • Overall decrease in PCE vapors beneath the former Shopping Center building • Overall decrease in PCE in the groundwater at the source area (Shopping Center) • Increase in PCE in downgradient groundwater wells (this is consistent with groundwater modeling predictions; these wells are not used for drinking water) When will the BSS be delisted? The BSS will be delisted (e.g., removed) from the State Superfund priority list when the site-specific cleanup levels are met and all criteria under ARM 17.55.114 have been met. DEQ will require performance monitoring until site-specific cleanup levels are met. Who do I contact if I have questions about the BSS? Kate Fry DEQ Senior Project Officer kfry@mt.gov 406-444-6426 4