Water Archives - Tata & Howard

Emergency Response Plan in Action at Cherry Valley & Rochdale Water District

While Emergency Response Plans (ERPs) are mandated by the EPA for most water supplies, the reality is that an ERP is a critical component whether mandated or not. The goal of an ERP is to guide and assist a water utility through emergencies, natural disasters, and articulated terrorist acts, and the intent is to present a methodical, sequential process to identify, investigate, and respond to an emergency.

ERPs are divided into two categories: Emergency Action Plans (EAPs) and Incident Specific Emergency Action Plans (ISEAPs). EAPs are broken down into five levels of emergency:

Level I – Routine
Level II – Minor
Level III – Major
Level IV – Natural Disaster
Level V – Nuclear Disaster / Terrorist Threat

ISEAPs are designed to “RIP and RUN,” outlining a specific action plan response:

Description of the event
Facilities affected
Initial notifications
Response actions
Follow-up actions

Water District Background

Cherry Valley & Rochdale Water District (CVRWD) is in the Town of Leicester, Massachusetts. It was originated by a Legislative Act in 1910 and the current population served is 3,700. It is staffed by three operators who also act as a superintendent, clerk, and treasurer. The District receives water from Worcester, MA via an automated interconnection and an 8” transmission main supplying Cherry Valley service area and maintaining operational levels in Cherry Valley storage tanks. Water is conveyed through 8-inch transmission mains from the booster pump station to supply the Rochdale service area and to sustain operational levels in the Greenville water storage tank.

While the transmission main route through the Cherry Valley service area is mainly public roads, most of the transmission mains servicing the Rochdale service area are through wetlands.

The Incident

The CVRWD suffered an incident on Sunday, October 27 in which the District’s ERP came into effect. At 3:30am, the On-Call Operator received a Low Water Storage Tank Alarm at the Greenville Water Tank. The Operator immediately notified the Superintendent. They compared SCADA trends of Greenville and Cherry Valley Tanks to confirm the alarm was for the Greenville Tank and that normal operational levels remained at the Cherry Valley Tank. At this point, they believed there was a leak in the Rochdale service area.

Sunday, October 27, 3:30am: Response and Notifications

Performed leak detection survey from booster pump station towards Rochdale service area, sounding a combination of hydrants and gate valves
Sounded triple gate just prior to the transmission main reentering the wetland and got a hit
Superintendent called first of the emergency contractors, Hydra Tech, to respond and stage at the Town’s Highway Department
Contacted Prowler Leak Detection Services to conduct a survey to pinpoint the leak
Continued to monitor the Greenville Tank level to confirm that Rochdale service area maintained positive pressure
Worked to pinpoint the leak while the Superintendent expanded the notifications
Superintendent of the Leicester Water Supply District (LWSD) discussed establishing a hydrant-to-hydrant (H-T-H) interconnection
Contacted the Town of Leicester Emergency Manager with regard to the evacuation of a Critical Care Facility and Dialysis Facility
Notified Leicester Fire Department to let them know that they had no use of hydrants in the Rochdale service area
Contacted Leicester DPW for permission to use the highway yard to stage equipment
Contacted EJ Prescott to deliver 300 feet of 2-inch water service line for H-T-H interconnection
Contacted Leicester Con Com and explained the emergency and the need to enter wetlands to repair transmission main; permission was granted and they prepared to deliver the Emergency Certificate on Monday, October 28
Superintendent contacted additional contractors to support operations

Sunday, October 27, 12:30pm: Wetland Road Construction

Began constructing road into wetlands to access leak
Road construction consisted of placement of 5’ x 18’ swamp mats which were covered with trap rock to allow construction equipment to build a 600-foot access road to leak location
Construction crews worked through the night to complete the road

Sunday, October 27, 1pm: Interconnection/Notification

Prior to activating H-T-H interconnection, contacted MassDEP (left message)
Activated H-T-H interconnection
Secured police detail to detour traffic
(2-inch water line temporarily ran on top of pavement through intersection)
Met with Emergency Manager and Deputy Fire Chief
Issued a reverse 911 to all three water districts advising of emergency and urging residents to conserve water
MassDEP called at 7pm, provided update, and agreed to call for another update the following morning (Monday)
Leak detection and road building ongoing with difficulty pinpointing leak; believed the leak was further into the wetland than originally expected
Correlation and road building went on through the night and into the next day
Even with H-T-H interconnection, Greenville Tank dropped to an uncomfortable operational level

Monday, October 28: Tanker Shuttle

T&H assisted with response and bulk tanker shuttle to fill the Greenville Tank
Calls to tanker companies posted on the MassDEP approved list resulted in securing three tankers from two companies
Booster pumping system had to be developed to fill Greenville Tank
Contacted Rain-for–Rent for a 21,000-gallon transfer tank, pump, generator and 4-inch quick connect hose which allowed for two tankers to off-load into the transfer tank at the same time
First day, two tankers operated 2pm-9pm
Tankers refilled using designated hydrant in Cherry Valley service area and unloaded at Greenville Tank
While tanker shuttle was in operation, MassDEP required bacteria and HPC samples from all approved coliform sample sites
District required to maintain a 1.0 ppm chlorine residual at the tank during tanker shuttle
Emergency light towers provided by Paxton and Holden Fire and Leicester Police Department
Tanker shuttle ran for 3.5 days and delivered ~300,000 gal of water to Greenville Tank

Tuesday, October 29, 12am: Repair/Return to Normal

Leak located, excavated, and repaired
Transmission main remained isolated and a tap was installed to allow for the addition of a sodium hypochlorite dosage of 300 mg/l
Dosage remained in contact for 24 hours
Main was flushed, water dechlorinated and sampled when achieved residual of 0.5 mg/l
Samples collected and analyzed for bacteria and HPC
All samples passed

Conclusion

The transmission main was back in service at 7:00am on November 1, and the total cost of the repair was $253,000.

There were some lessons learned from CVRWD’s emergency that the District plans to address for greater efficiency in the future:

Design and install fixed piped interconnection between LWSD and CVRWD for future use instead of the H-T-H connection
If necessary, start the Tanker Shuttle sooner
Evaluate options for replacement of 8-inch transmission main from the Booster Pump Station to the Greenville Tank; select best option, design, secure funding, bid, and replace

All in all, the District’s ERP provided the roadmap for a rapid response, clear notification system, and timely repair.

Need help creating or updating your ERP or RRA? We can help! Contact us today.

Well Field PFAS and PCE/TCE Removal, Danbury, CT

Tata & Howard is providing design and bidding of a treatment system for PFAS and PCE/TCE removal from three groundwater wells at the Kenosia Well Field.

PCE/TCE treatment includes using two 37 ‘H air stripping tower which will discharge into the new aerator wet well. Water will then be conveyed from the wet well to the four 12’W granular activated carbon vessels for PFAS treatment. Treated water will be pumped to the West Lake Reservoir for additional treatment.

The project also includes site work, electrical, HVAC and rehabilitation of the three existing groundwater wells.

Capital Efficiency Plan and Asset Management, Shrewsbury, MA

Tata & Howard has been providing engineering services for the Town of Shrewsbury since 2001. In 2014, Tata & Howard provided engineering services associated with the completion of a Capital Efficiency Plan. The hydraulic model was used to identify hydraulic deficiencies, critical customers were identified by the Town through a series of workshops held with utility staff, and the criteria combined with an asset management rating system were used to prioritize improvements to the distribution system.

The topography of the system causes many areas to have very high or very low pressures. In addition to prioritizing water main improvements, the study evaluated areas that should be incorporated into different service areas in order to reduce or increase pressures as needed.

As a result of the 2014 CEP and Asset Management Plan, the Town of Shrewsbury has been able to successfully utilize their budget in the most effective manner, prioritizing critical components and maintaining safe, clean drinking water for their residents. Additional services related to the CEP included a water distribution system study, hydraulic model update, water audit, and alternate water supply study.

Since the completion of the CEP, improvements and upgrades have included a booster pump station, water storage tank, replacement wells, a unidirectional flushing plan, a new water treatment plant for manganese removal, and a PFAS pilot study and design of a PFAS water treatment plant.

Leverett, MA Water Mains

Tata & Howard was retained by the Town of Leverett for design and permitting engineering services to expand the Amherst water distribution system into the Town of Leverett. The project involved the extension of the existing 8-inch water main in East Leverett Road, approximately 1.8 miles, to provide service to homes at the intersection of Cushman Road and Teawaddle Hill Road in Leverett with wells that have been contaminated by the Town of Leverett Landfill.

Tata & Howard reviewed available data with the Town for use in this project including existing GIS mapping, existing utilities, Town specification standards for materials and products, and boiler plate specification sections. Base plans for the project were developed utilizing the Town’s GIS data.

Borings were completed along the project route to determine existing soil conditions and the extent of rock/ledge, if any. In addition, soil borings assisted in determining the amount of needed polyethylene wrapping of the new ductile iron water main due to corrosive soils.

The design included the installation of water service connections to existing homes within the project area from the water main up to and including the curb stop at the property line. New hydrants were spaced every 500 feet and in-line gate valves were spaced no more than 1,000 feet apart. Surface preparation included temporary trench pavement and permanent trench pavement in accordance with the Town of Amherst and Town of Leverett standards. The draft design plans and specifications underwent a series of internal reviews for quality control. Tata & Howard provided the Amherst Public Works with a 50% and 90% draft for review prior to finalizing the project documents.

Barnstable, MA Maher WTP Upgrades

Photo courtesy of Waterline Industries Corporation

Tata & Howard provided engineering services for a completion of a pilot test proposal, pilot testing, and pilot test report to evaluate the use of granular activated carbon (GAC) to treat PFOS/PFOA, advanced oxidation to treat 1,4 dioxane, and LayneOx and greensand pressure filtration to remove iron and manganese from the source waters (Well No. 1, Well No. 2, and Well No. 3) at the existing Maher Water Treatment Plant. Pilot testing was performed, submitted, and approved by MassDEP in July 2017. The pilot test report was prepared and submitted in January 2018 to MassDEP.

Tata & Howard also provided engineering design, permitting, bidding, and construction services for the expansion of the existing Maher Water Treatment Plant. Upgrades include a new 90’ x 90’ pre-engineered metal building, GAC treatment, chemical feed upgrades, electrical upgrades at the existing plant including a new stand-by generator, and miscellaneous piping and site work. The new carbon filtration building include granular activated carbon (GAC) filters designed to remove PFAS. In addition to PFAS, the facility will include treatment processes to treat 1,4 dioxane and iron and manganese in the drinking water.

This project involved Massachusetts public construction laws and procedures.

Everett, MA Lead Service Line Replacement

Tata & Howard assisted the City of Everett, MA with their Lead Service Replacement Project from 2018-2024. Phases 1 and 2 included replacement or material confirmation of approximately 580 services between spring 2019 and fall 2022. Phase 3 of the project addressed an additional 300 services. Tata & Howard provided design, construction administration, and resident project representative services for all three phases of the project.

Design services included attending the kickoff meeting with City and reviewing existing information including tie-cards, the City’s existing GIS database that includes service material, and the City’s master list of services with service material. Each service was field verified to confirm exterior conditions. Each design phase included completion of 50% and 95% design documents, preparation of probable cost estimates, preparation of bid documents and coordination with purchasing agent, attending meetings with City, and providing recommendation to award contract to the lowest qualified bidder.

Construction Administration services for each phase included attendance at progress meetings and site visits, review of submittals, request for information, and purchasing change orders and payment applications. As-built record tie-cards were completed for each address and the master inventory of service material was updated as construction on each phase progressed.

Resident Project Representation services included full time on-site observation during construction, reviewing schedules, serving as Engineers’ liaison with Contractor, completing reports, reviewing pay apps, and issuing certification of substantial completion.

HVWP Water Distribution and Storage Improvement Project

Background

Hooksett Village Water Precinct (HVWP) Phase I Water Distribution and Storage Improvement Project is the first of three major drinking water components of the RTIA Tax Increment Financing (TIF) District economic development initiative sponsored by the Town of Hooksett. The project consisted of the construction of 1,800 linear feet of distribution system improvements in the Vista Drive area, a new 0.40 million gallon capacity glass-fused-to-steel tank, and 350 linear feet of associated transmission main from Daniel Webster Highway to Main Street.

The Precinct has been partnering with the Town, Sewer Commission, local businesses, committees, residents and area developers to encourage TIF-based infrastructure projects. TIF can be used to fund improvements that benefit the whole community by attracting new development, revitalizing blight, and/or enacting quality of life projects. This can significantly expand the tax base and provide more or easier access to services for residents with less financial impact.

Project Details

Hydraulic modeling studies completed in 2020 as part of the Precinct’s asset management program showed that distribution improvements were needed in the Vista Drive area to relieve a bottleneck that was critically restricting flow from the existing Quarry Tank and nearby wells. The Vista Drive area water main replacement/extension was listed as a Top Priority in the Precinct’s March 2021 Asset Management Plan Update. This area is the closest and primary source of water and fire protection for the TIF District, and a direct connection to the area is imperative to efficiently transmit water to the TIF District.

The Thompson Comer Tank is critical to water system hydraulics, not only for fire flow purposes but also for redundancy, emergency resiliency, and operational flexibility. It is inextricably linked to the operation of the Quarry Tank and the TIF District. Unfortunately, it had deteriorated to the point where it needed replacement. The new, slightly larger capacity replacement tank allowed the Quarry Tank to be taken offline as needed for O&M or emergencies; provide backup storage for the TIF district; allow the Quarry Tank to operate at 100% capacity; and improve overall energy efficiency by increasing off-peak operations.

Replacement of the existing Thompson Corner Tank also served as the permanent action plan to address a Significant Deficiency outlined by the New Hampshire Department of Environmental Services (NHDES) in October 2020. The deficiency identified was severe deterioration of the coating on the inside and outside of the tank. NHDES required that funding be authorized by March 2022 and a tank construction contract be awarded by October 2022.

The cost to replace the Thompson Corner tank and install the Vista Drive area water main and associated transmission main was $2,464,000 and was funded by 2021-22 NH Drinking Water & Groundwater Trust Fund (DWGTF) and NHDES American Rescue Plan Act (ARPA) Funds.

And the Winner Is…

Each fall, the Granite State Rural Water Association holds a drinking water taste test at its Annual Operator Field Day and Exhibit. In fall 2024, just after the completion of the project, HVWP had the honor of winning the contest!

Since Hooksett Village Water Precinct won the water taste test contest at Granite State Rural Water Association Operator Field Day this fall, they were able to represent New Hampshire in the National Rural Water Association’s The Great American Water Taste Test, where they won second place out of 43 systems in the National Rural Water Association’s “The Great American Water Taste Test” in Washington D. C. in February 2025. Mike Heidorn, P.G., Superintendent, represented HVWP and accepted the award.

We are very proud of the collaboration and efforts of both HVWP and the Tata & Howard team for the incredible success of our partnership.

Grafton Water District, Trinity Avenue Well Site and Pump Station

Tata & Howard provided engineering services for permitting, design, and bidding of the Trinity Avenue Pump Station at the Trinity Avenue Wellfield (new source) and provided assistance with permitting, design, and reporting to the Massachusetts Department of Environmental Protection (MassDEP) for the proposed Trinity Avenue Well site.

The property was owned by the Massachusetts Division of Fisheries and Wildlife (DFW), and the Grafton Water District swapped land with the DFW to obtain ownership and control of the Trinity Avenue site. Test wells were installed and short-term pump tests were completed on each of the wells. Based on the results of the tests, it was recommended to install a three well configuration of 18-inch x 12-inch gravel packed wells resulting in approximately 840 gallons per minute (gpm). The work under this contract included the completion of the Request for Site Exam and Pump Test Proposal for submission to MassDEP, installation and development of three (3) 18” x 12” gravel packed wells and pitless adapters, installation and development of approximately five 2-1/2” diameter observation wells, installation of two staff gages and piezometers, performing a five-day pump test, and collection and analysis of water quality.

The project also included an evaluation of alternatives for the access road including installation of a bridge or an open bottomed culvert, and Tata & Howard assisted with the preparation of permanent easements for the installation of utilities and roadway to the well site. In addition, Tata & Howard prepared and submitted an NOI to the Grafon Conservation Commission.

Design included double wythe block and interior concrete painted block with wood truss roof and asphaltic shingles. Security included chain link fence, gates, locks, intrusion alarms, and lighting. Tata & Howard also assisted with the coordination of the installation of three-phase power to site. Chemical feed at the station includes KOH for pH adjustment and chlorine gas for disinfection. Standby power was included in an outdoor enclosure. The design also included 900 feet of new 12-inch water main for 4-log removal.

Tata & Howard also provided construction administration and resident observation services.

Rehabilitation of a 130 Year Old Tank, Newton, MA

About the System

The water distribution system in the City of Newton, MA (City) serves approximately 90,000 people and includes 319 miles of water main ranging from 2-inches up to 30-inches. There is a southern pressure zone, a northern pressure zone, and three additional high service areas. All water is supplied by Massachusetts Water Resources Authority (MWRA) and the system utilizes two tanks, the Waban Hill Reservoir and the Oak Hill Tank.

Installation of the 24-inch cast iron piping in 1890

The Waban Hill Reservoir (Reservoir) is located in the Chestnut Hill area of Newton and serves the southern pressure zone. The Commonwealth Avenue Pump Station, operated by the MWRA, serves Newton’s southern pressure zone and fills the Reservoir. The Reservoir has a capacity of approximately 10 million gallons (MG) with four chambers that were built in stages: Chamber 1 was constructed in 1891, Chamber 2 in 1901, and Chambers 3 and 4 in 1917. Each chamber is approximately 2.5 MG. At the center of the reservoir is a gate chamber building that houses the influent and effluent valves and piping to each of the chambers as well as the 90-inch diameter central core standpipe.

As shown in Figure 1, there is a 24-inch diameter common inlet/outlet line that fills the interior standpipe and then overflows equally into all four chambers. When drawing, the 24-inch diameter check valve opens and draws through the effluent lines and out the common inlet/outlet. An additional 24-inch diameter inlet/outlet pipe is located in the corner of Chamber 2 that operates Chamber 2 only if needed. During construction, Chamber 2 was used to feed the system through the secondary inlet/outlet pipe while work was completed on the effluent valves for all chambers. During construction, the effluent pipe from Chamber 2 to the core was plugged so that work could be performed on the piping and valve while keeping Chamber 2 in service.

All chambers have a drain line and valve that manifold into a 24-inch diameter drain line that runs under the existing common inlet/outlet pipe. The bottom of the interior standpipe as well as the standpipe overflow both drain into the 24-inch drain line.

Design

The original scope of the repair project included rehabilitating the 90-inch diameter standpipe, replacing four 24-inch effluent valves, and replacing the asphalt shingle roof.

Prior to construction, it was important to review the impacts of removing Chambers 1, 3, and 4 from service on the distribution system. The existing hydraulic model for the City was used to evaluate pressures and available fire flow throughout the system with just Chamber 2 online. The inlet/outlet pipe for Chamber 2 runs down Commonwealth Avenue to the Pump Station (blue line in Figure 2) while the main inlet/outlet pipe from the Central Core runs down Ward Street to the Pump Station (red line in Figure 2). Changing the location of where water enters the system from the Reservoir in turn impacted the hydraulics at certain areas of the system, specifically at higher elevations north of the Reservoir. A recently installed 12-inch diameter interconnection between the two feed lines was opened, reducing the overall headloss in the system.

The design required a contingency plan, addressing potential challenges such as losing the entire Reservoir due to a water main break on the inlet/outlet pipe to Chamber 2. Through close coordination with T&H, the City, and MWRA, an emergency response plan was created that added enhanced scenarios. T&H evaluated the model for the best location of a mobile pumping unit and location of pressure relief valves. The City installed additional hydrants so the City could use MWRA’s mobile pumping unit if needed to pump from the northern pressure zone to the southern pressure zone, which required coordinating availability of equipment with MWRA.

Following a review of the challenges, the design scope was revised. Final design and bidding on the project included standpipe rehabilitation, effluent valve and piping replacement, drain valve replacement, check valve replacement, and asphalt shingle roof replacement as well as the standpipe cover and man-way, interior lighting improvements, and instrumentation.

Construction Challenges

There were many construction challenges to overcome as part of the design. Record drawings indicated an isolation valve was located on the common inlet/outlet pipe; however, the valve was unable to be found. A new valve was installed as a change order for the project.

The construction contractor was limited to light loads due to the uncertainty of the structural integrity of the roof to support specific loads, meaning no cranes or heavy equipment could be used, and spanning a crane from the access road to the gate chamber was cost prohibitive.

The existing valves were embedded in concrete and the flanges were severely deteriorated. Because of the age of the pipe, angles and bolt patterns were not easily matched with modern piping. Therefore, stainless steel piping was used to fabricate the needed angles to connect the new valves to the common inlet/outlet pipe.

The standpipe was showing signs of severe deterioration. Under recommendations from MassTank, specialty repairs were required to prolong the life of the standpipe. Steel plates were installed at the joints within the standpipe, both interior and exterior surfaces were sand blasted, a 200 mil epoxy coating was installed on the interior surfaces, and a 10 mil coating was applied to all exterior surfaces.

Initial filling of the reservoir caused Chamber 2 to fill faster than Chambers 1, 3, and 4 which caused the Commonwealth Ave. Pump Station to shut down. Therefore, the MWRA mobile pumping unit was relocated to the Waban Hill Reservoir and water was pumped from the hatch in Chamber 2 through the hatch in Chamber 1 which was connected to Chamber 3 and 4 through the central core.

Conclusion

Construction was completed in February 2024 and the project was highly successful with minimal service interruption due to a close working partnership with Tata & Howard, the City of Newton (client), and MWRA.

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.

Project Category: Water