Since its incorporation in 1912, the Water Supply District of Acton has supplied water to the residents of Acton through a distributed network of wells that pump water from shallow sand and gravel aquifers that were formed at the end of the last Ice Age. The Water District currently extracts water from seven wellfields, operates 4 treatment facilities, and maintains over 135 miles of water main. This system supplies the residents of Acton an average of 1.5 million gallons of water per day.
Until recently, a connection to the Massachusetts Water Resources Authority (MWRA) system, which extracts water from the Quabbin and Wachusett reservoirs, has never been seriously considered in our region. This changed in 2020, when the Massachusetts Department of Environmental Protection (MassDEP) established a 20ppt (parts-per-trillion) drinking water limit for PFAS (Per- and Polyfluoroalkyl Substances). Next year, the federal Environmental Protection Agency (EPA) is likely to impose a more restrictive national limit, which will reduce the allowable levels to about 4ppt. These new drinking water regulations for PFAS compounds are a thousand times lower than any prior water quality standard, and have motivated small towns throughout Massachusetts to question the sustainability of local water treatment. The cost to retrofit and maintain multiple treatment plants is very high, and the technology can be challenging. For this reason, and other issues facing public water systems, a number of MetroWest communities are now exploring an MWRA connection.
The MWRA currently delivers an average of 200 million gallons of water to 61 communities in the Commonwealth. It has substantial excess capacity and is encouraging non-member towns to connect to the system, offering to waive the connection fee for new communities.
In response to questions about connection feasibility, the MWRA funded the engineering consulting firm CDM Smith to perform an initial assessment of methodologies, cost, and timelines. Their report evaluates methods to expand the MWRA system to a group of 21 MetroWest towns that include Acton, Concord, Maynard, and Littleton. This expansion would require the construction of a new water tunnel that would connect to existing infrastructure in Framingham and pass through Sudbury and Concord to provide water to Acton and towns farther north and west (see map).
The detailed report addresses a wide range of engineering issues. The two parameters of greatest interest to the general public are cost and schedule. The total cost for expanding the MWRA distribution system to service 21 MetroWest communities is estimated to be in excess of 1 billion dollars, including a 25% cost increase contingency. The construction of approximately 50 miles of new high-capacity tunnels will require at least 25 years, and may take as long as 40 years.
While these cost and schedule numbers are informative, they don’t directly address the impact on the customers of the Acton Water District. Since Acton lies near the center of the towns within the study region, it is possible that water could be delivered to the Town within 10 or 15 years. With regard to Acton’s cost assessment, a rough estimate can be developed by dividing the $1 billion project estimate by the number of towns that would be serviced by the Metrowest expansion. The number of towns that will elect to take part in this project is currently unknown, but this simple calculation yields a cost projection that is in the range of $50 million to $100 million. For comparison, the current annual budget of the Acton Water District (which is a separate legal entity from the Town of Acton) is only $7 million.
To date, the Acton Water District has already approved more than $15 million towards construction costs to modify its existing treatment plants to comply with Massachusetts’ 20ppt PFAS limit. Capital costs to retrofit the Water District’s treatment facilities may increase further if the more restrictive regulations proposed by the EPA are approved. The long-term operational costs for additional pumping, maintenance, the replacement and disposal of filtration media, and staff time are difficult to predict, but will likely approach $1 million per year. In view of these projections, some stakeholders consider it prudent to investigate the feasibility of connecting to MWRA.
Removing PFAS from Acton’s drinking water will not eliminate the public’s exposure to these contaminants. According to model assumptions used by the MassDEP and the EPA, only about 20% of PFAS exposure is due to drinking water for most consumers. Other PFAS intake pathways include food, food packaging, clothing, upholstery, household products, and personal care products.
Dr. Parenti is a member of the Town of Acton Water Resource Committee and the Acton Water District Finance Committee.
