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Frequently Asked Questions


    • Manufactured gas plants produced “town gas” by heating coal, coke, and/or oil in a closed vessel.
    • The gas generated by the process was captured and cleaned of impurities before being stored in large round structures, known as gas holders, and piped locally to users.
    • Town gas was distributed first for lighting streets, homes, and businesses, and eventually gained acceptance for heating and cooking.
    • At its peak use in the first half of the 20th century, approximately 100 manufactured gas plants were operating across Massachusetts.
    • The manufactured gas era ended when natural gas became widely available through the interstate pipeline system.
    • There have been an estimated 50,000 manufactured gas plants that operated in the U.S. between 1851 and 1960. None have operated in the last 50 years.
    • Yes, there was a manufactured gas plant that operated at the southeast corner of Commonwealth Avenue and Mount Hope Street, at 439 Mount Hope Street.
    • This former plant is referred to as the former Mount Hope Street manufactured gas plant, and the cleanup area is referred to as the “site.”
    • The gas plant ceased operations in 1928.
    • The boundaries of the site are shown on the figure below.

    • As with many industrial processes, gas manufacturing produced byproducts and residues.
    • Coal tar is the primary byproduct associated with these former manufactured gas plant sites.
    • When these plants closed, the tar was often left on the property in underground structures. Over the years, the tar and other residues may have impacted the environment.
    • Although manufactured gas plants are believed to have operated under the standards and practices of their times, today we know more about their potential impacts.
    • Liberty, along with its environmental contractor, AECOM, have studied the site extensively.
    • The studies included sampling of soil and groundwater both on the site and in adjacent properties, and sampling of sediment and surface water within the Ten Mile River and Mire Brook.
    • The environmental studies helped identify where residues or environmental impacts are located, and which require attention.
    • The areas which required attention included portions of the former manufactured gas plant property. Remediation work at this area was completed in 2009.
    • The environmental studies also identified portions of the Ten Mile River and Mire Brook and portions of several adjacent properties along Commonwealth Avenue and Towne Street that require attention. Several of these properties have been purchased in recent years by Liberty in anticipation of this work. The properties will be returned to their former use as residential properties upon completion of the Project.   
    • Yes. The environmental cleanup is being done in accordance with the Massachusetts Contingency Plan (MCP) and an Administrative Consent Order issued by the Massachusetts Department of Environmental Protection.
    • Under the MCP, all work is heavily regulated and must meet all relevant environmental laws and regulations.
    • The MCP establishes a road map through the regulatory process beginning with the reporting of an environmental condition to MassDEP, through investigation, assessment, remediation or clean-up, and ultimately site closure.
    • In our activities at the site, we are also working closely with the Town of North Attleboro, including the Town Manager, the North Attleboro Conservation Commission, and the Department of Public Works.  The work will also be performed in accordance with an Order of Conditions issued by the Town’s Conservation Commission and a permit issued by the US Army Corps of Engineers.
    • Drinking water is provided by the Town of North Attleboro, which treats and tests water quality.  There is no reason to believe that the Town’s drinking water sources have been impacted. 
    • The environmental studies were exhaustive and were performed pursuant to the state regulations.  It is the Licensed Site Professional’s opinion that the investigations performed, both at the gas company facility property as well as neighboring properties, have identified the suspected sources and residual impacts associated with former manufactured gas plant operations.
    • Liberty has already completed significant cleanup actions to address environmental impacts at the portion of the site which it owns at the southeast corner of Commonwealth Avenue and Mount Hope Street, including:
      • Removing about 1,700 tons of impacted soil, which was transported to an appropriately licensed facility for treatment or reuse, and
      • Constructing a cover over remaining impacted soil and installed stormwater management systems.
    • Additional actions are planned that will comprise the long-term cleanup project for the site. These actions will aim to restore the environment at the former gas plant site and neighboring properties so that it continues to be safe to use over the long term. These actions include:
      • Removal of impacted soil.
      • Removal of impacted sediment within select areas of the Ten Mile River and Mire Brook.
      • Restoration of river, wetland, and upland areas.
      • Returning adjacent properties to prior use.
    • The site work is scheduled to begin in Summer 2020 and the construction activities will take an estimated 9 to 15 months to complete.
    • This schedule is dependent on several factors, especially weather conditions.
    • Liberty has already completed the design plans and specifications and is in the process of receiving its final environmental permits. The plans detail how the work will be performed and have been discussed in detail with the affected property owners in order to obtain access agreements to facilitate the work.
    • When construction begins, the limits of the construction (or work) areas will be staked, and certain areas will be cleared of brush and vegetation.
    • Temporary dams will be constructed in Mire Brook and Ten Mile River to allow for river/brook diversion.
    • Certain areas of the site will be “de-watered” – so that soil or sediment can be removed “in the dry.” Water collected during this process will be treated in a temporary water treatment system or transported to an offsite treatment facility.
    • Once soil and sediment are removed, the excavated material will be taken off-site to a licensed disposal or treatment facility.
    • Trucks hauling the excavated materials off-site will be covered so material will not be spilled or discharged onto Town roadways.
    • The excavated areas will then be filled with clean soil.
    • Once this work is completed, impacted areas will be restored. Vegetation will be planted, and other wetland mitigation efforts will be employed to restore these resource areas as close as possible to their pre-construction condition. 
    • The restored areas will be monitored and maintained, as necessary, for a period of 10 years to ensure the effectiveness of the restoration. 
    • Liberty’s environmental projects are carried out under plans that are designed to ensure the health and safety of workers and the neighboring community.
    • During the cleanup work, the site will be secured by a fence, and the gates will be locked when the workers are not present.
    • During work on adjacent properties, the work area will be temporarily fenced.
    • At various times, traffic may be managed to permit trucks to enter and leave the site along Commonwealth Avenue.
    • During the work, the air will be monitored for dust and chemical emissions, using equipment that works much like smoke detectors.

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    • Activities related to environmental cleanup projects were included as one of the "COVID-19 Essential Services" in Governor Baker's COVID-19 Order issued on March 23 and that designation was confirmed in Governor Baker’s Order issued on March 31. On May 18, Governor Baker announced his phased reopening plan which included the resumption of additional construction activities which had not previously been deemed a COVID-19 Essential Service. The May 18 announcement by the Baker Administration also included sector specific protocols, including mandatory safety standards and recommended best practices for construction-related projects.

    • Liberty is committed to maintaining good health and safety practices during the course of this work and believes that such commitment is central to the completion of a successful project. To ensure the health and safety of onsite workers and the local community during the ongoing pandemic, Liberty has instituted COVID-19-specific protocols designed to protect the health and safety of its employees and the local community. The contractor performing the work will be required to adhere to all of Liberty’s health and safety protocols and has been instructed to remain current with the Baker Administration’s COVID-19 guidance in general and as relates specifically to the construction industry in the development and implementation of its project-specific health and safety plan.

    • We expect the remediation work may produce noise, typical of any construction site, and odors at times.
    • Coal tar smells very similar to mothballs or roofing tar. Workers will be able to reduce the odors with foam and tarps.
    • Odor suppressing foam will be employed to mitigate air emissions at the Site.
    • It should be noted that despite all precautions, there will be odors emanating from some of the ongoing activity.
    • Our perimeter air monitoring program will provide us with information that we will use to alter our work practices to minimize odors and air emissions.
    • Therefore, it is possible that you will smell coal tar at concentrations that do not exceed any risk or action levels.
    • During the work, the air will be monitored for dust and chemical emissions, using equipment that works much like smoke detectors.
    • Noise levels will also be monitored so that controls can be implemented, if necessary, to minimize impacts to the neighborhood.
    • Operating hours will be in accordance with the Town’s bylaws, and will typically extend from 7:00 a.m. to 7:00 p.m., Monday through Saturday.
    • No road closures are anticipated, but one lane of traffic on Commonwealth Avenue might be limited at certain times to accommodate traffic entering or leaving the site.
    • The structure at 61 Commonwealth Avenue will be demolished to allow for the required excavation activities.
    • The Town will receive rights to a portion of that property for purposes of accessing and maintaining the retaining wall along the Ten Mile River. In addition, Liberty will replace or repair certain portions of the existing retaining wall as part of its project. 
    • Liberty will return the remaining properties along Commonwealth Avenue and Towne Street to their former use once the cleanup program is complete.

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