Funding Assistance Archives

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.

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 chosen to use novel media because it 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 designing the facility which is being funded through the MassDEP State Revolving Fund.

Water Treatment Plant, Amherst, MA

Tata & Howard contracted with the Town of Amherst for design, permitting, and bidding of the 1.5 million gallon per day (MGD) Centennial Water Treatment Plant, to treat surface water from the Pelham Reservoir System. The existing Centennial WTP, located in the Town of Pelham but supplying the Amherst Public Water System, has a history of issues with turbidity, color, and disinfection byproducts in the form of total trihalomethanes (TTHM) and haloacetic acids (HAA5) because of high levels of organics in the Pelham Reservoir System. Due to the age and condition of the existing WTP, the filters which were the primary treatment process at the existing WTP were no longer effective at removing organics, leading to a decrease in finished water quality and total WTP capacity. The existing Centennial WTP has been offline since 2018 due to water quality, as well as infrastructure concerns related to a lightning strike which impacted pumping equipment and communications at the Centennial Water Treatment Plant’s raw water pump station.

Based on the results of the pilot study performed by the Town of Amherst, Tata & Howard completed design of the new Centennial Water Treatment Plant including dissolved air flotation (DAF) clarifiers and granular activated carbon (GAC) filtration for treatment of organics, color, turbidity, and low levels of iron and manganese. The DAF system includes polyaluminaum chloride for coagulation, two rapid mix chambers, and three package DAF units which each include two high rate flocculation chambers, two low-rate flocculation chambers, a saturation tank, effluent collection system, discharge weir, mechanical skimmers and beach, and associated appurtenances and controls. Three dual media filter chambers with a silica sand/course garnet base layer and GAC above are located downstream of the DAF units, prior to final chemical addition.

Additional chemical feed includes a gaseous chlorine system for 4-log inactivation of viruses, gaseous ammonia for chloramine formation, sodium fluoride for dental health, and sodium hydroxide for pH adjustment and corrosion control. The new facility also includes an advanced Supervisory Control and Data Acquisition (SCADA) system for automated control of the water treatment plant. Operators for the Town of Amherst will be able to remotely monitor and control operation of the Centennial WTP, through a recently extended town fiber optic cable network.

The design of the Centennial WTP included provisions to maintain the Amherst water distribution system, as even with the Centennial WTP offline, the clearwell of the existing facility also serves to maintain pressure in a small portion of the water distribution system between the Centennial WTP and a booster pump station. The Centennial WTP feeds the majority of the water system (excluding the portion between the WTP and the booster pump station) by gravity. Since the existing WTP including the clearwell will be demolished prior to construction of the new WTP, design and construction of the new WTP will include a temporary water storage tank to maintain pressure and keep all connections active in the high service area of the Amherst Public Water System.

Permitting for this project included a BRP WS 24 New Treatment Plant application with MassDEP, Site Plan Review with the Pelham Zoning Board of Appeals, and a Request for Determination of Applicability (RDA) with Pelham Conservation Commission.

The Centennial Water Treatment Plant was recently bid and awarded to R.H. White Construction Co. of Auburn, MA for a contract amount of $18,876,000. This project received funding though the Drinking Water State Revolving Fund program, and construction is expected to be completed by the summer of 2025.

Wiscasset Completes Capital Efficiency Plan™ Infrastructure Improvements

The Wiscasset Water District (WWD) completed its final phase of water main replacements for the Town of Wiscasset, ME. In 2007, Wiscasset, a rural coastal town in Maine, embarked on a long-awaited infrastructure improvement program to replace the Town’s century-old waterlines. The Wiscasset Water District, engaged Tata & Howard’s services in 2010, to prepare a Capital Efficiency Plan™ (CEP), to identify areas to the Town’s water distribution system needing rehabilitation, repair, and/or replacement.

The Capital Efficiency Plan™ report which included hydraulic modeling, system criticality, and an asset management plan, provided the Utility with a database and Geographic Information System (GIS) representation for each pipe segment within their underground piping system. The CEP report also prioritized the water distribution system piping improvements and provided estimated costs to replace or rehabilitate the water mains.

In response to the CEP™ findings, the Wiscasset Water District retained the services of Tata & Howard, to perform design, bidding, construction administration, and resident project representation services for a series of water main projects.

Phased over 10 years, the plan included replacing 33,150 feet of 12-inch and 8-inch piping, installation of a water storage tank mixer, SCADA upgrades, and office landscaping improvements.

The final phase of water main replacements is scheduled to be completed during the summer of 2018 and will fulfill all the Priority I water main improvements identified in the 2010 CEP™ report. The projects were funded in part by a combination of USDA Rural Development grants (6 total) and loans (7 total), as well as coordination with the Maine Department of Transportation and Rural Development.

The final phase of water main replacements that was completed during the summer of 2018 fulfilled all the Priority I water main improvements identified in the 2010 CEP™ report. The projects were funded in part by a combination of USDA Rural Development grants (6 total) and loans (7 total), as well as coordination with the Maine Department of Transportation and Rural Development.

Ozone Water Treatment Plant in Franklin, MA

Tata & Howard provided design and construction services for a new water treatment facility that houses a 1.2 mgd ultrafiltration system and completed a pilot test that consisted of an evaluation of two separate ultrafiltration technologies. Franklin Wells No. 1 and 2, located off Hayward Street in Franklin, Massachusetts were installed in the 1940’s with a combined safe yield of 1.2 million gallons per day. Due to high concentrations of iron and manganese in the groundwater, the wells were only used to meet peak water demands during the summer months. The construction of the water treatment facility recaptures the yield from these two sources.

The water treatment facility consists of a main building which houses static mixers, ozone feed equipment, chemical feed equipment, prefilters, membrane filtration equipment, instrumentation and controls. Treatment consists of ozone oxidation followed by membrane ultrafiltration. The project was funded in part by the Massachusetts Water Pollution Abatement Trust through a low interest state revolving fund loan.

The overall treatment scheme is as follows: ozone injection, oxidation of iron and manganese in an ozone contact tank, prefiltration, treatment through two ultrafiltration membrane skids, chlorination prior to a clearwell, and fluoride addition prior to discharge into the distribution system. The plant is designed to recycle backwash water and membrane recirculation water to the head of the plant utilizing two decant tanks. Ozone is produced on site utilizing compressed air, while a LOX tank is available to allow for the production of additional ozone if required in the future.

Water Main in Palmer, MA, funded by a CDBG

Tata & Howard provided design of 1,400 linear feet of 12-inch diameter water main on Griffin Street, High Street, and Stewart Street. Work included the preparation of design plans and specifications, hydraulic modeling to determine main size, and letter and cost estimate to the Palmer Community Development Department. Tata & Howard also provided construction administration and resident observation services. The project was funded by a USDA Rural Development Community Development Block Grant (CDBG).

Funding Assistance for WWTF Upgrade in Lyndon, VT

Upgrade for a 750,000 gallon per day extended aeration wastewater treatment facility to an A/O biological facility. Assistance included acquiring State CWSRF planning grants and USDA Rural Development grant for extensive improvements including separation of combined sewer/stormwater collection systems (CSO), advanced Class A sludge treatment, and reconstruction of original 1970’s treatment facility to new Anoxic/Oxic Treatment System. Total grant funds were $7,275,000.

Water Treatment Facility, Water Mains, and River Crossing Horizontal Directional Drilling

Tata & Howard provided design and construction services for the construction of a 1.44 mgd water treatment facility. The water treatment facility consists of a concrete block masonry building housing filtration equipment, a laboratory and office space, and associated piping, instrumentation and controls. Building components including HVAC, plumbing, and electrical services were incorporated in the facility. Other work included, but is not necessarily limited to, site work, exterior piping systems, and electrical work at an existing well pump station.

Tata & Howard also provided design and construction services for the installation of approximately 5,000 linear feet of new 12-inch high-density polyethylene (HDPE) water main (two parallel pipes at 2,500 linear feet, each) via directional drilling beneath the Pemigewasset River, connecting the City’s Franklin Falls Well Site and the City’s Acme Well Site.

Tata & Howard provided design and construction services for the installation of approximately 2,655 linear feet of 12-inch diameter Class 52 ductile iron water main, water services, and associated valves, fittings, and hydrants on Hill Road (New Hampshire Route 3A) and a service road connecting Hill Road to the City’s Acme Well site; approximately 4,000 linear feet of 12-inch water main, water services, and associated valves, fittings, and hydrants on Lawndale Avenue, Webster Lake Road, and Kimball Street; approximately 3,200 linear feet along Lawndale Avenue; 1,200 linear feet along Webster Lake Road; and 600 linear feet along Kimball Street. The work also included pavement restoration on Lawndale Avenue, Webster Lake Road, and Kimball Street.

The project was funded by NHDES and the USDA Rural Development office.

FEMA Hazard Mitigation Grant in MA

FEMA grant — The exposed water main ran under the bridge on Mechanic Street

Tata & Howard provided engineering consulting services to the Town of Monson, Massachusetts for the relocation of the 8-inch diameter water main on Mechanic Street.

The main was originally constructed in 1897 under the streambed; however, after 117 years in this location, the decrease in surface water elevation had exposed the water main. The water level averaged about one inch below the top of pipe, exposing the top portion of the entire section of main that crossed the brook, approximately 15 linear feet of main. Exposure of the water main made it susceptible to freezing during the winter months, which could have resulted in a break and subsequent lost water or contamination from the brook to the Town’s entire water system, potentially resulting in significant costs to residents and to repair, clean, and disinfect the system. The main provides potable water to approximately fifty residents. There were only two gate valves located at the ends of Mechanic Street. As a result, if the main were to fail at the bridge, the entire street would have to be shut down in order to repair the damage, disrupting water service for the 50 serviced residents.

The Mechanic Street Bridge has a history of failure. As a result of a major flood event in 1955, the bridge failed and was completely replaced in 1956. The bridge ran directly over the water main, which posed an additional threat to the main should the failure reoccur. Although the main was unaffected during the previous failure, its weakened condition made it more susceptible to failure in a similar event.

Tata & Howard provided funding assistance and the project qualified for and received a FEMA Hazard Mitigation Grant for 75% of the cost of the project. The work included the preparation of design plans and specifications for the relocation of the 8-inch water main to a self-supporting beam structure attached to the bridge abutments on Mechanic Street. The project also included bidding, permitting, construction administration, and resident observation.

Water System Improvements and Funding Assistance, VT

Greensboro Fire District No. 1 (GFD#1), situated on the Northern portion of the Green Mountains in Vermont, requested assistance with their water distribution and treatment systems due to deficiencies identified in a sanitary survey conducted by the State of Vermont. This contract addresses these deficiencies and provides the District a more robust covered water storage tank, secure buildings that house controls and chemicals and related equipment, emergency power generation, and water metering.

As part of the project, Tata & Howard helped GFD#1 secure funding that included a 45% USDA Grant for the originally planned project with an estimated budget of $2,900,000. During the design phase, the District lost their primary well source due to an extended drought. Tata & Howard engineers worked with the District to secure a 100% USDA grant for the cost of constructing a new municipal well source and associated emergency generator and related appurtenances.

Tata & Howard provided design, construction administration, and resident observation for the water system improvements project. Construction began in the spring of 2015 with the setup of a temporary water storage system and demolition of the existing water storage tank roof structure. Precast planks and a ballasted membrane roof were then installed, providing safe, quality water. Two new small buildings were constructed to house chemicals and water well piping and controls, along with an emergency generator to provide continuous water in case of interruption to electrical power.

Shared Wastewater Treatment Facility, VT

CLIENT: The Towns of Canaan, VT and Stewartstown, NH

PROJECT: Shared Wastewater Treatment Facility

THE CHALLENGE: The existing wastewater treatment facility was 40 years old, costly to operate, and did not meet state and federal water quality standards. In addition, the Towns had very limited funds with which to upgrade the treatment facility.

THE SOLUTION: Tata & Howard helped the Towns secure a $2.412 million low-interest, long-term loan and $1.69 million in grant funds from the U.S. Department of Agriculture (USDA) Rural Development in order to build the new facility.

Tata & Howard, Inc. provided complete consulting engineering services for the construction of the wastewater treatment facility project which included the complete upgrade of four pump stations as well as the upgraded 0.185 mgd, 3-cell lagoon wastewater treatment facility. In addition, Tata & Howard’s St. Johnsbury, Vermont office, formerly Leach Engineering Consultants, provided full design services for all of the upgrades.

The Towns now enjoy a state-of-the-art, reliable wastewater treatment facility that meets the Effluent Discharge limits to the Connecticut River and provides for a more efficient treatment process. The new influent screening and grit removal processes extend the life of the treatment facility components. In addition, septage receiving provides for additional income and also provides service to the residents of the Towns that are not on public sewer.

The design included numerous energy-efficient features such as variable-frequency drives (VFDs) on aeration blowers, solar-powered lagoon mixers, a wood pellet boiler for heat, energy-efficient windows, and insulated concrete form (ICF) walls, resulting in a reduction in annual operation and maintenance costs. The pump stations were upgraded to eliminate operators entering below grade structures and to allow for future pump replacement that would be lower cost with it would be with the original centrifugal pumps.

PROGRESS: The project is complete, and the Towns celebrated the completion of their shared $4.12 million wastewater treatment facility with a ribbon-cutting ceremony in Canaan, VT.

Services: Funding Assistance