PFAS Mitigation, Shrewsbury, MA

A PFAS Journey to Determine Effective Management and Treatment Options

Tata & Howard is working with the Town of Shrewsbury, MA to address perfluoroalkyl and polyfluoroalkyl substances (PFAS) in the groundwater. The Town of Shrewsbury water system serves a population of approximately 38,300. The system consists of about 200 miles of main, nine active groundwater wells from three well sites, three pressure zones, six storage tanks, and one water treatment plant. The 7.0 million gallon per day (mgd) Home Farm Water Treatment Facility utilizes biological treatment for removal of manganese.

In 2020, Shrewsbury detected PFAS in the wells. Sampling has indicated that PFAS is present in most of the wells operated by the Town but under the maximum contaminant level (MCL) of 20 nanograms per liter (ng/L) for PFAS6 as regulated by the Massachusetts Department of Environmental Protection (MassDEP) which includes the sum of concentrations for PFOS, PFOA, PFHxS, PFNA, PFHpA, and PFDA. Raw water from one well site, the Sewell Well, has been consistently higher than 20 ng/L; but the finished water from all wells after treatment at the Home Farm Water Treatment Plant has been in compliance and consistently less than 16 ng/L. Most of the PFAS is in the form of PFOA and PFOS which are the two compounds for which the EPA has developed a proposed MCL. The PFOA indicated by the green bar in Table 1 is higher than the proposed Federal MCL of 4 ng/L.

Currently, the Town has been managing the sources to improve water quality and stay under the current MCL of 20 ng/L for PFAS6. A mass balance is utilized to estimate finished water PFAS concentrations based on updated sample results and changes in the operation of the sources. Tata & Howard created the base tool which can be used to see how changes to PFAS levels or flow rates can affect the finished water concentration.

Table 2 represents existing conditions. The numbers used for PFAS are the highest results from each individual well observed in a year of sampling data, showing the finished water level is about 16 ng/L.  As long as the PFAS concentrations in the wells remain consistent, the Town will remain in compliance. If sample results change and they see an increase in PFAS concentration at Sewell, the Town will make adjustments using the mass balance to manage the sources to remain in compliance.

 The Town cannot manage sources like this indefinitely. They decided to move forward with reviewing PFAS treatment options and pilot testing to determine the best course of action if/when treatment is required.

Tata & Howard and the Town considered three treatment options. The first option is anion exchange, which uses a resin with positively charged ions. These are typically single use resins and require one to three minutes of empty bed contact time. The next option is Granular Activate Carbon (GAC) which uses adsorption. This media can be made from different types of carbon sources that can be recycled through thermal reactivations and requires a ten minute empty bed contact time. There are limitations with GAC on some of the short chain PFAS. The third type is novel media, which includes other types of media that do not fall into the first two categories. The novel media piloted uses an adsorption process that is classified as a single use resin and has a two to three minute empty bed contact time.

Pilot System

Shrewsbury’s pilot testing utilized three anion exchange resins from two suppliers (one of which was regenerative), a coal-based GAC, and a novel media. The novel media selected works like GAC since it is not as sensitive to chlorine and chlorides, which can impact the effectiveness of anion exchange resins.

The GAC pilot test utilized two 6-inch columns in series rather than one very tall column to give more flexibility for installation and backwashing. A total of 10 gallons of media were installed with a loading rate of 7.5 gal/ft2 and an empty bed contact time of approximately ten minutes. The anion exchange and novel medias each utilized one 6-inch column with five gallons of media installed, a loading rate of 11.25 gal/ft2, and an empty bed contact time of approximately two minutes.

The water source was a tap on the effluent line from the existing filters using finished water that had been treated for manganese removal but not any of the chemical additions of KOH, phosphate, chlorine, and fluoride. There were control valves so the water only came through the unit when the treatment plant was online, which is typically more than 20 hours per day.

There was an initial baseline water quality sampling event at the start, at the end of week 20, and at the end of piloting. PFAS samples were taken day one, day seven, and then monthly for the duration of the pilot. Samples were taken from the 25% sample tap until breakthrough (50% of the raw water PFAS levels, so between 6 and 7 ppt), then at the 50% tap.

Table 3 shows the result from the different taps at the end of the pilot.  The anion exchange results are from the best performing anion exchange resin. GAC was first detected in week 8 with breakthrough in the 25% tap in week 16 and the 50% tap in week 44. There was a detected amount in the final sample tap in week 64, which was the final week of the testing.

Anion exchange had the longest time to first detect but the 25% breakthrough for all anion exchange and novel media were all within a sample event or so of each other and occurred between weeks 44 and 52. The novel media had breakthrough of the 50% tap at week 60 and was detected in the 100% tap at the final week while the anion exchange was ND in the 100% tap at the end of the pilot.

Table 4 is a summary as to what the permanent filter system may look like. The filters are similar in size but the number of recommended filters differs for each resin. The overall building footprint is similar as well. The anion exchange did perform slightly better than the novel media, however, the overall PFAS removal results over the duration of the pilot was similar. Because of this, construction costs, long term media replacement costs, and operational considerations were included as part of the media selection process.

The Town has not yet made a final decision on media type, but it appears that the novel media may be the best fit for the Town’s needs.  Specifically, the novel media allows for some backwashing and chlorination, reducing the potential of biofilm buildup and potential capacity loss due to increased headloss through the media. Additionally, the novel media has a smaller footprint in comparison to GAC.  The Town of Shrewsbury’s current PFAS levels do contain mostly PFOS and PFOA at concentrations higher than the proposed Federal regulations for those two compounds. Also, based on reviewing the data of the PFAS6 compounds, PFOA was the compound first detected for all media; also, the majority of the detected PFAS6 concentrations in the effluent throughout the pilot were PFOA.

One additional challenge moving forward is the design of the facility so the water goes through the manganese treatment first, the new PFAS treatment next, and finally utilizes the existing clearwell for chlorine contact, with finished water pumping into the system, all while keeping the existing treatment online during construction and start up.  Tata & Howard is currently completing a preliminary design to better estimate costs before completing the final design, permitting, and ultimately construction.

Steele Street Pump Station, New Britain, CT

Steele Street Pump Station

Tata & Howard provided engineering services for modifications to the Steele Street Pump Station including installation of a new constant-run type pump station with variable frequency drives; and design and installation of a new permanent outdoor diesel generator and automatic transfer switch.

In addition, T&H provided construction administration and resident observation services for the modifications to the pump station.

Steele Street Pump Station Standby Generator

Water Infrastructure and Conservation Adjustment (WICA) Water Mains, Hazardville, CT

Tata & Howard provided design, bidding, and construction administration services for approximately 2,600 linear feet of new water main in Enfield, CT.

Approximately 500 linear feet of existing 10-inch asbestos cement water main on Hazard Avenue was replaced with new 12-inch HDPE water main. This water main crosses a ConnDOT 48-inch culvert and the replacement was completed using horizonal directional drilling. Approximately 2,100 linear feet of existing 2-inch steel and 6-inch asbestos cement water main was replaced with new 8-inch ductile iron water main. Wetlands permitting and coordination with the ConnDOT were required to cross the existing 48-inch culvert on Hazard Avenue.

Bidding services and construction administration services with full-time resident project representation and site visits were also provided.

New Hampton Road Water Main Project

Tata & Howard completed design, funding, and construction phase services in the City of Franklin, NH for the $3.5M New Hampton Road Water Main Project. The new 16-inch and 12-inch ductile iron water mains replaced a 1940s era unlined cast iron water main (approximately 14,000 linear feet) with a history of main breaks and extends over three miles from the Babbitt Road Booster Station to the Sanbornton Wellfield.

The water main was identified as a priority in the 2016 Capital Efficiency Plan prepared by Tata & Howard and will provide improved water quality, distribution pressure, and fire protection.

Tata & Howard assisted the City with maximizing the NHDES SRF Loan with the City’s paving program funds to fully reconstruct 9,000 linear feet of New Hampton Road as part of the project.

Auburn, MA Water Storage Tank

Tata & Howard was contracted to provide Design, Construction Administration, and Resident Project Representation services for the construction of the Prospect Street Water Storage Tank in Auburn, MA.

The project consists of the construction of a 1.0-million-gallon capacity glass-fused-to-steel water storage tank with associated piping and appurtenances, electrical work, a tank mixing system, and site work.  Other work included the decommissioning and demolition of the pre-existing 500,000-gallon capacity welded steel water storage tank at the site.

 

 

 

Maher Water Treatment Plant – Groundbreaking Ceremony

On Wednesday, August 7, 2019, the Hyannis Water System and officials from MassDEP held a ceremonial groundbreaking for construction of the new Maher Water Treatment Plant designed by Tata & Howard, Inc.

The $12 million water system upgrade, funded by the MassDEP SRF program, will enable the Town to meet new and stricter federal and state regulations for emerging contaminants. The new plant will treat elevated levels of Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), 1,4-Dioxane, iron, and manganese in the three drinking water production wells at the existing facility.

The water filtration building at the Maher Water Treatment Plant has a design capacity of 1,500 gallons per minute. Using granular activated carbon filtration, the successful removal of PFOS/PFOA will be obtained. Advanced oxidation with peroxide and ultraviolent (UV) light will treat 1,4-Dioxane. Lastly, greensand pressure filtration will not only remove the iron and manganese, but also extend the useful life of the granular activated carbon.

Tata & Howard has been instrumental in the evolution of this project. In December of 2016, Tata & Howard provided a conceptual design report to Barnstable’s Department of Public Works. A pilot test report was submitted in early 2018 and design began shortly thereafter.

The Hyannis Water System currently consists of four water treatment facilities, four storage tanks, 12 well pumping stations, and a 107-mile distribution system. The water system provides drinking water services to approximately 18,000 residents through 7,249 metered service connections to residential and commercial properties.

Waterline Industries Corporation of Seabrook, NH constructed the filtration building, and Tata & Howard provided construction administration and resident observation. The facility was operational in October 2020.

Newton, MA – Lead Service Replacement Program

Tata & Howard was contracted to provide design, construction administration and resident project representation for the replacement of 588 lead services in Newton, MA. Although the water that services the City is not corrosive, replacing lead services is a cautious and preventative measure to avoid lead from potentially leaching into tap water via the service connection which is located from the water main to the meter.

Lead service replacement program in Newton, MA. Excavator and men.

Lead pipes are more likely to be found in older cities and homes built before 1986. As such, the affected lead services in Newton were installed between 1875 and 1915. Of the 588 total services;

  • 318 were full-service replacements (from water main to meter)
  • 266 were partial-service replacements (from curb stop to meter)
  • 4 were street only replacements (from water main to curb stop)

Prior to the construction phase of this project, Newton residents were notified about the City’s Lead Service Replacement Program (LSRP). Although not required, those wishing to participate in the program were able to take advantage of a ten-year, no interest payment plan through the City.
Under the LSRP, the City replaced, at its own expense, the portion of the water service pipe which was within the public way from the street line in front of the homeowner’s property, to the City water main. The homeowner then had the option to replace the portion of the water service pipe that ran from their meter to the property line.

Lead service replacement program in Newton, MA. Newton home with construction cones.

Tata & Howard scheduled construction and coordinated with the residents who elected to participate in the LSRP. Crews from C.J.P & Sons Construction worked to excavate the properties and remove/replace the water service pipes. In most cases, limited excavation of homeowner property was needed.

When the project reached completion, 427 total services had been replaced.

Lead service replacement program in Newton, MA. Excavator and men. Construction worker replacing pipes.

(De)leading the Way – Marlborough, MA

The City of Marlborough, MA (home of T&H headquarters) contracted Tata & Howard for the design, pre-construction services, construction administration and resident observation of approximately 1,200 lead water service connections.
Until 1944, lead was widely used in service lines and is quite common in many of the older cities and towns in Massachusetts.

Lead pipes currently placed between the streets and homes of identified Marlborough residents will be replaced with copper pipes in five phases – each phase consisting of approximately 250 homes.

Tata & Howard will be involved in each phase, reviewing tie cards, attending field surveys to determine what each service placement will entail, and advising contractors on the quantity of pipes to be installed in each location.

Although lead is known to be  a major health risk to children and pregnant women, the supplier of Marlborough’s water, Massachusetts Water Resources Authority (MWRA), treats all water to reduce lead from getting into drinking water.
   
   

Meadow Walk Mixed-Use Wastewater Design / Engineering Services

Tata & Howard provided engineering services for final design and construction documents associated with the design of a wastewater treatment facility utilizing membrane bioreactor (MBR) technology for the 50-acre Meadow Walk development at 526-528 Boston Post Road in Sudbury, Massachusetts. The site is a former Raytheon engineering and R&D facility.

National Development / Avalon Bay mixed-use residential and retail development, Boston Post Road, Sudbury, MA.

Believing the site was well-suited for mixed-use residential and retail development, Sudbury selectmen and residents voted to approve zoning and development plans proposed by National Development and Avalon Bay. The site was in development for two years and is nearing completion. The project consists of several independent components, which collectively comprise a mixed-use development with new open space, retail, and restaurants as well as walkable access to adjacent retail, office, and other services along Boston Post Road. The project also included local roadway improvements, major upgrades to the streetscape and landscaping, wastewater treatment improvements, and improved water quality.

Tata & Howard was contacted initially to prepare studies of existing conditions and proposed modifications to enhance and then upgrade the wastewater facility and disposal area on the site. Additional out-of-scope changes included value engineered alternatives and additional design services. The existing wastewater treatment facility was over 25 years old and required increased discharge limits; conversion to an MBR system to achieve higher removal of BOD, TSS, TN, turbidity, and other wastewater constituents; additional treatment redundancy; upgrades to meet current Massachusetts Department of Environmental Protection (MassDEP) guidelines; increased groundwater recharge; odor control; replacement of old infrastructure with a new pump station, gravity lines, and force main; a change to mixed land/water use to result in wastewater generation that could be more efficiently treated at the new wastewater treatment facility; and a new leaching field.

Upgrades included infrastructure and a new leaching field.

Chamberlain Highway Receives New Water Main Connections

The Chamberlain Highway in Meridan, Connecticut has 536 linear feet of new 16-inch ductile iron main and two new fire hydrants. After Tata & Howard completed several test pits to verify connection locations at each end of the new main, construction work started on May 3, 2018 with the installation of a 16” x 16” tapping sleeve and valve at the north end of the project. This existing water main at the north end connection was originally installed in 1894.

Chamberlain West Main

Work progressed south until the new main was approximately 50 feet away from the other connection point in West Main Street. Connections to the existing main in West Main Street was performed over a 36-hour period due to the complexity and amount of utilities around the service connection, including a live 24-inch water main five feet away and multiple telephone conduits located 6 inches above the replaced main. Tata & Howard personnel on site at all times to observe that work was in performed in accordance to the plans and specifications.

Following the completion of the Chamberlain Highway water infrastructure improvement project, work to replace two water mains on the state-owned bridge crossing Sodom Brook in Meridan will begin.