Large Municipalities Archives

Four Water Storage Tanks, Westfield, MA

Tata & Howard provided engineering services to the City of Westfield for its water tanks, most recently the Provin Tank. For background, the City of Westfield water system consists of 242 miles of water main ranging in size from under 4-inches up to 24-inches and has one main service area. There are also four small high service areas, each of which utilizes a booster pump station. There are nine groundwater supply sources and one active surface water supply source, the Granville Reservoir, and there are interconnections with the City of Springfield at three locations. The system has a total of four tanks with a total capacity of 11.2 million gallons (mg). In 2014, a Condition Assessment Report was completed for each of the City’s four prestressed concrete tanks in order to evaluate condition of each tank and provide recommendations for required rehab work.

The site of the East Mountain Tank, a 2.7 mg tank constructed in 1961, was deemed a “hard hat zone” due to its declining condition. The dome and dome cap were determined to be in fair to poor condition, showing significant deterioration of concrete, and it was further determined that the dome would need to be completely replaced. Due to the significant rehabilitation required, the City decided to construct a new tank. Tata & Howard started the design of the new East Mountain Road Tank in 2017, and the new tank was constructed and operative by 2020.

Wanting to be proactive and avoid the deterioration found at the old East Mountain Road Tank, the City contracted Tata & Howard in 2020 to design and bid the rehab of the City’s three other tanks: the Northwest Road Tank, Sackett Tank, and Provin Mountain Tank.

Rehab work required on the Northwest Road Tank, which was constructed in 1975, consisted of exterior cleaning and coating, repairing of concrete patches, replacing access hatches, replacing the dome vent, and installation of a new overflow screen.

The Sackett Tank, which was more recently constructed in 1991, only required exterior cleaning and coating and replacement of an access hatch.

The Provin Mountain Tank, which is located in the southeastern corner of City, is a 5.0 mg prestressed concrete tank originally constructed in 1967. Measuring 148 feet in diameter and standing 40 feet high, it connects to the system via a 16-inch line. The original scope of the rehab work needed was as follows:

Exterior cleaning and coating
Concrete patch repairs
Injecting a polyurethane grout into a crack
Replace dome hatch and dome vent
Install new overflow screen
Evaluate and repair exposed and broken prestressed wires

With all of these tanks being prestressed concrete, prestressed wires are wrapped tightly around the dome ring as reinforcement to hold the weight of the water. In October 2021, the contractor arrived on site to complete the rehab work on the Provin Mountain Tank. When they started chipping away at loose concrete, it was discovered just how bad the condition of the dome ring was. Each day, more wires were found broken, with more than one third of the total wires found to be broken. The dome was in danger of potential collapse.

The team reconvened to discuss next steps on the project. During rehab work, the contractor surveyed the surrounding area to see if any residents were potentially in the path of the tank if it were to collapse. The tank level was lowered to about 25% capacity, and it was decided to complete repairs on the tank to act as a temporary fix. Temporary repair work began in October 2021 and was completed in April 2022, consisting of the following:

Remove all loose gunite material and broken wire by hand
Apply shotcrete to the dome ring face and provide a uniform surface
Install prestressing strand, Teflon shims, and anchors
Apply shotcrete to fully encapsulate the prestressing strand
Repeat for subsequent layers (estimate 3-4 layers, 17 strands total, 0.6 inch each)
Pressure-wash top surface and face of dome ring
Seal surface cracks on the top surface of the dome ring with Sika 55
Apply a waterproof coating on the dome ring apron and face (Tamoseal)

This repair work extended the useful life of the tank by 2-5 years. The question then was whether to abandon the existing tank or replace it with a new tank. To evaluate if a replacement tank was needed, a storage evaluation was completed. US Census trends and ASR data used to estimate service populations and demands to 2041 showed that the future MDD was estimated at 10.7 mgd. Emergency storage, equalization storage, and fire flow storage were calculated and totaled for current and future demand conditions, showing that the future required storage for the system was approximately 2.77 mg. While having a water storage surplus may initially sound like a positive, too much of a surplus can lead to water quality issues such as water age and disinfection byproducts. This data indicated a replacement tank was not needed based on needed system storage alone.

Hydraulic impact was also studied. Pressure decreased 2-4 PSI depending on which sources were running, and the available fire flow decreased up to 600 gpm, but was limited to the area around the tank which is mostly residential. Resultant flows were sufficient for the residential area.

While storage and hydraulics showed that the tank was not needed, it was determined that there would be significant lack of fire protection in much of the system if the Sackett Tank was offline for repairs or other issues in addition to elimination of the Provin Mountain Tank. Due to the lack of fire protection under this scenario, it was ultimately recommended to replace the tank.

EPS modeling was used to evaluate change in water age for various size replacements. It was ultimately decided to construct a 2 mg tank with the recommendation that the City change the operation of their wells to increase fluctuation in tank levels. Overflow was decided to match the old tank at 428 feet, and the inside diameter of the new tank would be 79 feet compared to 148 feet of the existing tank. The new Provin Tank is currently in design with an anticipated bid this fall, with site work expected to begin by late fall. Given that temporary repairs were completed in April 2022, we are on track to replace the tank within the 2-3 year time frame based on the lifespan of the temporary repairs.

The existing tank will be demolished after the new tank is in service.

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.

Hemlocks Raw Water Pumping Station

Tata & Howard provided engineering services for design, bidding, construction administration, and resident observation to Aquarion Water Company for improvements to their existing Hemlocks Raw Water Pumping Station in Fairfield, CT. The project included refurbishing five 300 hp centrifugal pumps and motors, replacing the existing variable frequency drives (VFDs), installing new piping, check valves, and strainers for each pump.

Hemlocks Pumps — BEFORE improvements to the Hemlocks Pumping Station.

As this facility is a source of supply for Aquarion’s Main System, it needed to be kept operational throughout the construction. The sequence of work required a single pump to be taken off line; refurbished; reinstalled with new piping, VFD, and appurtenances; tested and placed back into service prior to the next pump being taken off line.

Hemlock Pumps — AFTER improvements to the Hemlocks Pumping Station.

Another important aspect of the project was to replace the existing strainers so that they were easier for the plant operators to clean as they get clogged with eels. To simplify maintenance, new stainless steel wye strainers with bottom access to the screens were installed on the suction side of each pump.

Air Piping Improvements – Flagstaff, AZ

Tata & Howard provided professional engineering design services to the City of Flagstaff, AZ for the replacement of three aeration units, as well as interior air piping improvements for the Rio De Flag Wastewater Reclamation Facility (WWRF). In addition, approximately 400 linear feet of existing air piping were replaced at the Rio De Flag WWRF. The exterior pipe was visibly leaking air. For technical and operational reasons, screw compressors were chosen over turbo blowers. Tata & Howard provided design services including preparation of plans, specifications, and bid documents for the installation of the new screw compressors.

The existing air flow exterior pipe gaskets had deteriorated with the heat of the existing compressed air to where the piping was a safety problem and was also wasting energy. Tata & Howard worked with the City to provide shop approvals and assisted the City’s inspector to ensure the project met the plans and specifications.

The existing blowers at the plant were 25 years old, had reached the end of their useful life, and did not ramp up and down with the wastewater flow. The new aeration units will flow pace with the changing incoming flow and saved the City enough electrical energy that it is projected to pay for the upgrade in eight years. The electrical power company (APS) offered a large rebate to reward Flagstaff for taking this energy and money saving opportunity.

Worcester, MA Hydraulic Modeling and Capital Efficiency Plan™

Tata & Howard completed a hydraulic model update and Capital Efficiency Plan™ for the City of Worcester. As part of the project, Tata & Howard updated and verified the City’s existing hydraulic model, which has over 550 miles of water main. Work included three days of fire flow tests throughout the City and allocation of demands using up-to-date billing and parcel data. Phase II of the project, the Capital Efficiency Plan™, identified and prioritized areas for improvement within the distribution system. Our services included evaluating the condition of the existing distribution system infrastructure to determine the adequacy of meeting present and future demands, calculating needed storage requirements, assessing and prioritizing system improvements, reviewing and evaluating typical fire flows throughout the system, creating a pipe asset management rating system, and recommending improvements to the distribution system.

Tata & Howard calibrated the hydraulic model under extended period simulation for an evaluation of the Super High Service Area with the Chester Street Tank off-line due to rehabilitation. The configuration of the service area included two distinct zones. The Chester Street Tank is located in one area and the Howland Hill and Apricot Tanks are located in the other area. To remove the Chester Street Tank from service, an evaluation of supply and pressures needed to be completed. The results of the analysis included running both zones off the Apricot Tank and utilizing the Chester Street Pump Station to maintain pressures within the vicinity of the Chester Street Tank.

Southern Maine Regional Water Council (SMRWC) Regional System Study

Tata & Howard was retained by the Southern Maine Regional Water Council (SMRWC) to complete a Regional System Study for the Portland Water District (PWD), Maine Water Company – Biddeford & Saco (MWCB&S), Kennebunk, Kennebunkport, Wells Water District (KKWWD), Sanford Water District (SWD), South Berwick Water District (SBWD), York Water District (YWD), and Kittery Water District (KWD).

The purpose of the study was to provide a detailed update to their 2008 Regional Water System Master Plan Study, which studied possible interconnections between the water systems within the SMRWC. A combined water distribution system regional hydraulic model was developed using the hydraulic models of each individual water system. The regional hydraulic model was used to evaluate the hydraulic feasibility and impacts of the proposed interconnections as well as the potential of transferring water from northern systems to southern systems through a completely connected and open system. The PWD and MWCB&S have large water sources and are interested in exploring the option of providing water to southern systems. The study evaluated the needed infrastructure improvements, each system’s available water supply, and demands through the potential and existing interconnections.

The study also examined the effects that the proposed system improvements and interconnections would have on water quality. Not all water systems treat water in the same way; therefore, finished water is unique to the chemicals and treatment techniques used by each system. Specifically, pertinent available data was collected and chemicals used for coagulation, sequestering, primary disinfection, secondary disinfection, corrosion control, pH adjustment, and dental health were reviewed. Raw and finished water parameters such as turbidity, alkalinity, temperature, pH, and total hardness were also collected. Of the seven participating water systems in the study, three disinfect with chloramines and four disinfect with only chlorine solution. Operating the systems together as a permanent solution to water supply concerns would require modifications to the treatment processes in some if not all of the systems. Ideally, each water system involved in water sharing would need to agree to a treatment method to give each system acceptable water quality and eliminate concerns with blending systems.

The identified improvements were based on hydraulic feasibility. Infrastructure recommendations at the interconnection locations include construction of new water mains, pressure reducing valves, and booster pumping stations.

Regional Intermunicipal Interconnection Evaluation, MA

Through a grant from the Pioneer Valley Planning Commission, Tata & Howard was retained by the City of Northampton Department of Public Works (Northampton) and the City of Easthampton Water Works (Easthampton) to complete a Regional Intermunicipal Interconnection Evaluation for the Easthampton, Hatfield, Northampton, Southampton, and Williamsburg water systems. The purpose of the study is to evaluate potential water distribution system intermunicipal connections and emergency water supply. A combined water distribution system regional hydraulic model was developed and used to evaluate the hydraulic feasibility and impacts of the proposed interconnections. The study evaluated the needed infrastructure improvements, system available supply and demands, and available supply through the potential interconnections.

Potential interconnection locations between Northampton and Easthampton were considered at four locations, between Northampton and Hatfield, between Northampton and Williamsburg, and between Easthampton and Southampton. Infrastructure recommendations at the locations include construction of new water mains, meter pits, flow meters, pressure reducing valves (PRV) and portable pumping systems. The Massachusetts Department of Environmental Protection (MassDEP) Water Management Act (WMA) permitted and registered pumping volumes for each system’s sources was evaluated for potential supply to other communities. Northampton and Easthampton have surplus supply, while Hatfield, Williamsburg, and Southampton are approaching their WMA permit or registration allowable withdrawal volumes.

The study determined the following:

Three of the four potential interconnection locations between Northampton and Easthampton could be utilized in an emergency by isolating portions of Northampton’s system. An interconnection that could serve all of Northampton would require a pumping system.
A pressure reducing valve would be required to supply Hatfield from Northampton and a pumping system would be required to supply Northampton from Hatfield.
Due to the location of the Williamsburg interconnection along Northampton’s transmission main route, and the limited amount of water available from Williamsburg, an interconnection from Williamsburg to Northampton is not feasible.

There is an existing hydrant to hydrant interconnection between Easthampton and Southampton that has been utilized to supply water to Southampton during periods of high summer demands. To supply the entire Southampton system, a pumping system would be required, and a PRV would be required to maintain adequate pressures if Southampton were to supply Easthampton.

Organizational Plan, Westfield, Massachusetts

Tata & Howard completed a Water/Wastewater and Related Departmental Organizational Plan for the City of Westfield. Prior to the start of work, the organization included a Water Resources Superintendent, a Wastewater Superintendent, and other department heads to provide water, wastewater, stormwater, and highway services. The chief project goal was to seek alignment of people, business processes, and technology.

Tata & Howard reviewed relevant documents, facilitated individual interviews with knowledgeable managers and staff, and conducted on-site workshops as appropriate to evaluate the City’s current organization against desired business goals and industry best practices. We recommended a revised organization to the City which is in the process of being approved through the City Council. Upon acceptance of the new organization, a detailed report will be submitted.

Water Storage Tank Replacement, Hamden, CT

Tata & Howard provided evaluation, design, construction administration, and resident observation services to the South Central Connecticut Regional Water Authority (SCCRWA) for the replacement of the Whitney-Wintergreen water storage tank. The project included an analysis of SCCRWA’s Whitney-Wintergreen service area to determine the appropriate volume of storage needed to serve its customers, and a 1 million gallon concrete tank was constructed to replace the existing 1.5 million gallon steel tank at the same site. The project also included demolition of the existing tank as well as stormwater management at the site. The project was completed in September of 2015.

Maine Water Company Pump Station

Tata & Howard assisted Maine Water Company with mechanical, structural, and architectural design of a new high service zone booster pump station on Barra Road within the Biddeford-Saco water distribution system. The new pump station replaced the existing Alfred Road station, providing pumping capacity to meet current demands in a majority of the City of Biddeford as well as room for future expansion. Funding for the project was provided in part by the Maine Drinking Water Program State Revolving Fund (DWSRF).

Mechanical design for the project consisted of sizing and selection of three (3) centrifugal booster pumps, associated piping, and appurtenances. The pumps were sized with input from a hydraulic model of the system developed by Tata & Howard, and they were selected to maximize the available flow from a 16” cast iron pipe line that crosses the Maine Turnpike from the water system’s major storage reservoir. A pipe gallery was incorporated into the slab and foundation design as well as insulated concrete form (ICF) foundation walls. Per the Owner’s request, the architectural design used colors and materials similar to the other buildings within the surrounding commercial office park. Also, a gable roof canopy was added to the design (pictured below) to help shield the emergency backup generator from the elements. Precautions were taken to ensure proper air flow and ventilation was achieved to meet the requirements of the generator. Construction of the pump station was completed in 2015.

Markets: Large Municipalities