Commerce Street Plume Superfund Site

Public Informational Meeting

August 12, 2015

Town Hall Williston, VT

Agency Contacts

U.S. EPA (Region 1) • Karen Lumino, Remedial Project Manager • Anni Loughlin, ME/VT/CT Section Chief • John Hultgren, Enforcement Counsel

VT DEC • Michael Smith, Hydrogeologist • Trish Coppolino, Environmental Program

Manager

Evening’s Agenda

• Informational Meeting (7 – 7:45) EPA presents proposed cleanup plan, time for Q’s & A’s.

• Formal Public Hearing (8 - ?) EPA accepts verbal comments on the proposed plan.

Comment Period ends September 4, 2015

How to Comment Verbal Comments

• Accepted only during public hearing on August 12, 2015

Written Comments • USPS – must be postmarked by Sept 4, 2015 • FedEx, UPS – must be sent by Sept 4, 2015 • Fax, email – must be sent by Sept 4, 2015

Administrative Record

What is it?

• Collection of documents and information that forms the basis for EPA’s selection of a response action, in this case the proposed cleanup plan.

• Available for public review.

Administrative Record

Where is it?

• Alling Memorial Library (Williston) • EPA’s Records Center (Boston) • Some documents linked to EPA’s website

www.epa.gov/region1/superfund/sites/ commercestreet

Superfund Process

Remedial Investigation Delineate nature and extent of contamination in soil, groundwater, surface water, sediment and indoor air. Complete.

Risk Assessment Evaluate the potential for human health and ecological risks from exposures to contamination. Complete.

Superfund Process (cont)

Feasibility Study Comparative screening of remedial technologies based on cleanup goals developed by EPA in consultation with the State of Vermont. Complete.

Proposed Plan EPA’s preferred cleanup plan; subject to public comment. Ongoing: Aug 6 thru Sept 4, 2015.

Superfund Process (cont)

Record of Decision Document issued by EPA that describes the remedy selected by EPA, with the concurrence of the State of Vermont, after considering all comments received by the public. Planned for September 2015. Includes a Responsiveness Summary in

which EPA addresses in writing all comments received during 30-day comment period.

Superfund Process (cont)

Remedial Design/Remedial Action Environmental engineers/contractors design, build and implement the remedy until the cleanup levels selected in the ROD are met.

Institutional Controls Legal mechanisms (e.g., municipal ordinance) put in place to protect human health until cleanup levels are met.

Groundwater

• 70-acre plume extends from Commerce Street to Kirby Lane to South Brownell.

• Primary contaminant of concern is trichloroethylene (TCE) and to lesser extent, tetrachloroethylene (PCE).

• Contaminant plume is at depth in sandy overburden.

TCE Plume

TCE plume (S-N along Commerce St)

TCE plume (W-East across S Brownell,

Kirby & Commerce St)

Proposed Groundwater Cleanup

• In Situ (“in place”) treatment – inject materials such as hydrogen peroxide, ozone or molasses into the more contaminated portions of the plume to convert contaminants into less toxic by-products and enhance subsurface conditions so that naturally-occurring microbes that digest contaminants can thrive.

Groundwater Cleanup (cont)

• Monitored Natural Attenuation – monitor, track and evaluate the on-going natural degradation in the portions of the plume that are less contaminated.

• Reclassify to non-potable – restoration to drinking water quality is VT’s goal for all groundwater in the state. Until that goal is met, a Class IV designation will prevent drinking and other household uses.

Groundwater Cleanup (cont)

• In situ technologies have a proven track record. Active portion of remedy expected to occur in 4 pulses, each lasting about 3 weeks, over the course of 2 to 3 years.

• Expected to reduce the time to achieve drinking water standards from hundreds of years to decades.

Soil

• Soil in the area of the former wastewater lagoon at 96 Commerce Street (formerly Mitec Systems) is contaminated with chromium (presumed hexavalent), PAHs and arsenic.

Proposed Soil Cleanup

• Excavate approximately 630 cubic yards of contaminated soil for off-site disposal at a licensed facility.

• Backfill with clean soil, re-grade and re-seed.

Soil Cleanup (cont)

• Expected to take a month to complete, will be done during work hours to minimize noise and impacts from small increase in local truck traffic.

• Dust suppression techniques will be used and particulate monitoring will be in place along perimeter of parcel.

Indoor Air/Sump Discharge

• EPA’s indoor air study across the Site confirmed VT’s earlier findings that vapor intrusion is not an area-wide concern, with one exception.

• EPA did not find water in sumps to be contaminated nor was sump discharge impacting surficial soil, with one exception.

Indoor Air/Sump Discharge (cont)

• Vapors emanating from contaminated water in the sump at one property on South Brownell poses a potential health threat to the residents.

• In 2014, VT DEC installed a vapor mitigation system in the home that vents vapors to the outside.

Indoor Air Cleanup

• EPA’s remedy will ensure that a vapor mitigation system to protect the residents at the South Brownell home will continue to operate, and, allows for vapor controls in other structures, if deemed necessary in the future.

• South Brownell sump water will be treated on site prior to discharge to the ground and indirectly to groundwater.

Surface Water/Sediment

• EPA determined that there are no risks to human health from direct contact with surface water or sediment in the unnamed stream that runs parallel to Commerce Street on the eastern side of the Site.

• EPA determined that there are no ecological impacts from Site-related contaminants in the unnamed stream.

Institutional Controls

• Restrictions on the use of groundwater are needed until such time as it no longer poses a risk to residents from ingestion or other household uses, and, to protect utility and other construction workers from direct contact with or inhalation of vapors while working in saturated soils.

• ICs are typically in the form of municipal ordinances and/or deed restrictions.

EPA believes this remedy is…

Protective of human health and the environment.

Uses proven technologies such as excavation and groundwater treatment to reduce toxicity, mobility and volume of contamination.

Achieves cleanup objectives in a reasonable time frame.

And is…

Cost effective.

Total estimated cost is $8.4 million.

Requires a 10% Vermont cost share.

Written Comments on this Plan No later than September 4, 2015, send to:

Karen Lumino EPA Region 1 5 Post Office Square, Suite 100 Mailcode OSRR07-4 Boston, MA 02109 Email: lumino.karen@epa.gov Fax: 617-918-0348