PROJECT: Mountain Street Water Treatment Plant Valve Replacement
Hole in clarifier pipe caused by failed check valve
THE CHALLENGE: The three check valves on the clarifier influent feed lines were failing and, as a result, the disc was consistently hitting the downstream pipe spool piece, eventually causing each section to develop holes and leaks.
THE SOLUTION: Rather than simply replacing the check valves with the same style valve, we decided to dig deeper. We believed the discs were failing due to turbulence generated by an upstream modulating valve, so we researched alternative valves. We found that most alternative valves required a longer lay length than the existing check valves, which would have required replacement of the influent piping as well as reconfiguration of the valves and flow meters on each of the clarifier influents that feed the three units back to the header.
With additional research, we identified a flanged duckbill check valve that could actually be inserted between two flanges within the pipe, with the flange of the check valve sandwiched between the two flanges of the existing pipe configuration. The valve itself was located within the influent piping and allowed for installation without having to significantly alter the clarifier influent piping. As a result, the Owner saved on the cost of the valve replacement as well as avoided an extended shutdown time, as each clarifier would have been out of service for a far longer duration if extensive influent piping modifications were necessary.
PROGRESS: The project was successfully completed in October of 2014.
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.
THE CHALLENGE: More stringent USEPA and MassDEP regulations, including Stage 2 Disinfectants/Disinfection-by-Product Rule (S2 D/DBPR) and the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), resulted in the Town of Falmouth needing to make a decision on whether to construct a filtration facility in compliance with the SWTR or to upgrade disinfection processes only at the existing Long Pond Water Treatment Facility (LPWTF) to maintain the existing Filtration Waiver.
THE SOLUTION: Because the existing LPWTF utilized no filtration to remove bacteria, organics, and particulates, the water quality entering the distribution system was an ongoing concern with elevated turbidity and organics leading to seasonal color, taste, and odor complaints; elevated bacteria and concentrations; and elevated algae counts. In addition, the high doses of chlorine needed to maintain the disinfection residuals required for an unfiltered supply reacted with the organics in the raw water to form disinfection by-products. Therefore, the only viable option for the Town of Falmouth was a new water treatment plant. After evaluating 22 treatment processes and developing eight treatment alternatives for pilot testing, only one treatment process met all goals: Dissolved Air Flotation (DAF) clarification, intermediate ozone followed by filtration. This alternative also scored favorably on the benefit/cost analysis.
Tata & Howard provided design and construction services for the new Dissolved Air Flotation (DAF) facility with a design capacity of 8.4 million gallons per day (mgd) for the Long Pond surface water supply for the Town of Falmouth, MA. The water treatment plant (WTP) utilizes coagulation, mixing, flocculation, dissolved air flotation (DAF), dual media filtration including granular activated carbon (GAC) above sand, chemical feed systems, and an intermediate ozone feed. Building components include HVAC, plumbing, fire sprinkler, gas and electrical services. Other work included site work with exterior piping systems, exterior above and below ground tanks, sludge holding lagoons, construction of a garage, new raw water intake and pump station, directional drilling of raw water mains, and demolition of equipment and site piping at the existing water treatment facility.
As part of the project, Tata & Howard provided design and permitting of a new 8.4 mgd intake and raw water pump station (RWPS) for the WTP. The new intake and RWPS were constructed along the eastern shore of Long Pond and replaces the existing intake and Low Lift Pump Station. The new intake and RWPS includes a two-level intake consisting of two 8.4 mgd rated intake screens installed at elevations -3 feet below mean sea level (MSL) and -13 feet below MSL. The 36-inch HDPE intake pipeline connects the intake screens to the new RWPS located approximately 150 feet from the eastern shore of Long Pond. An air burst system was designed in the RWPS to provide a means for routine cleaning of the new intake screens.
An accelerated 11 month design and permitting schedule, followed by contractor prequalification, bidding, and award, were completed in time to qualify the Town for >$3M in principal forgiveness.
Design included the following:
• 300 Drawings
• 1,200 pages of Specifications
• SRF PEF application
• Monthly project meetings
• Coordination with Building Department
• Coordination with Board of Health
• Coordination with Town IT Department
• Coordination with Police and Fire Departments
• Coordination with Gas and Electric Utilities
Permits included the following:
• Wetlands Protection Act-Local Conservation Commission
• Board of Health
• Remediation General Permit (NPDES)
• Massachusetts General Permit
• Environmental Notification Form
• Massachusetts Historical Commission: Intensive Archaeological Survey including 200 test holes
• MassDEP Approval to Construct WTP: BRP WS 24
• DWSRF PAC
• 401 Water Quality Certification
• NHESP – Turtle Protection Plan
• Chapter 91 Waterways License
• U.S. Army Corps of Engineers General Permit
The construction of the Long Pond Water Treatment Plant progressed on schedule and was completed in 2017. The plant included numerous sustainability and energy efficiency initiatives including the following:
Recycling spent backwash water to head of plant and back into the treatment process, after it passes through a plate settler to remove solids.
Recycling laboratory analyzer and filter influent piping gallery analyzer discharges back into the treatment process.
Using filter-to-waste water after a filter backwash sequence as supply water for the next backwash, instead of using finished water for backwashing.
Discharging cleaner supernatant water off the top of the lined lagoons to an unlined infiltration lagoon and back into the ground to minimize residuals.
Use of local/native plants for landscaping, including an irrigation system using collected rainwater from roof drainage.
Interior and exterior LED lighting fixtures.
Variable Frequency Drives (VFDs) on HVAC equipment and process equipment motors.
The plant went online on October 18, 2017. The work was funded under the SRF program. The Long Pond Water Treatment Plant received an ENR New England 2017 Best Project Award in the Water/Environment category, and an Associated Builders & Contractors of Massachusetts Eagle Award in the Public Works – Environmental category. For a drone video of the new water treatment plant taken by the general contractor, Methuen Construction, please see below:
Tata & Howard provided construction administration, resident observation, and start-up services to the Milford Water Company for the construction of the Dilla Street Water Treatment Facility. The 5.2 mgd facility treats water from a combination of lake, river, and wells, utilizing dissolved air flotation (DAF) clarifiers and granular activated carbon (GAC) filters. The facility will replace the existing slow-sand and diatomaceous earth (DE) treatment currently utilized to treat the existing surface and groundwater sources, respectively. The facility was required to address and satisfy an Administrative Consent Order (ACO) issued by MassDEP.
Tata & Howard also completed design and oversight of a redundant cast-in-place chlorine contact tank, and has been contracted to provide engineering services for project review and construction oversight for the installation of raw water screens on intakes of both the lake and river sources. These improvements were mandated by MassDEP as part of the approval of the Dilla Street facility design.
Tata & Howard completed pilot testing, design, permitting, bidding, and construction management services for the Town of Wayland’s Baldwin Pond Water Treatment Plant which included iron and manganese removal. The facility received MassDEP approval to go online and became Wayland’s first public building to receive an occupancy permit in the last 30 years. The need for the facility arose from high iron and manganese content in Wayland’s water. The facility also addressed any concern over the three Baldwin Pond wells which were under close scrutiny to determine if they were “under the influence of surface water.” The 7,500-square-foot, 1.5 million gallons per day, state-of-the-art water treatment facility was constructed to meet current and future regulations for many years ahead. The design included ozone oxidation, ultrafiltration membranes, waste recycle, and chemical feed for coagulation, pH adjustment, fluoridation, and disinfection. The treatment facility utilizes ozone oxidation and ultrafiltration to remove iron and manganese from the blended raw water from the three water supply wells. Although other constituents are also removed through this process, the basis of this plant is to optimize the removal of iron and manganese.
The Baldwin Pond Water Treatment Facility project was highly successful through good communication and teamwork between Tata & Howard’s construction management team, the general contractor Methuen Construction, and the Town of Wayland. With less than 1% of the contingency budget applied to change orders towards the end of the project, the Town was able to do additional work. The additional work included replacing raw water mains and upgrading the existing garage onsite. A dedication ceremony for the facility was held with Representative Scott Brown, and representatives from MassDEP, Methuen Construction, and Tata & Howard joining the Town of Wayland in commemorating the completion of the facility.
Tata & Howard assisted the Town of Winchester to meet the Collection, Management, Operation, and Maintenance (CMOM) requirements in the Town’s NPDES General Permit. The work consisted of the preparation of an outline for the Full Collection System Operation and Maintenance Plan, which included descriptions of staffing, management goals, information management, condition assessment, recent studies, and construction activities. Tata & Howard was also retained to prepare the Full Collection System Operation and Maintenance Manual, which included updating the outline, preparing a preventative maintenance and monitoring program, identifying sources of suspected overflows and back-ups, preparing a program for preventing I/I related effluent violations, and a public outreach program regarding I/I control.
Additionally, Tata & Howard has assisted the Town of Winchester with three phases of improvements to the Winchester Wastewater Treatment Facility (WWTF), I/I investigations, repair and rehabilitation of the sewer collection system to remove I/I, and securing funding to upgrade the WWTF and sewer collection system.
Tata & Howard provided engineering services for the evaluation, design, and construction of approximately five miles of pressure and gravity sewer to serve the mountain resort community of Jay, Vermont. The design also included the upgrade to air release structures for 4.5 miles of force main and upgrade of two pump stations, one a progressive cavity station.
In addition, Tata & Howard provided engineering services including planning, evaluation, design, permitting and construction services for the Troy-Jay wastewater treatment facility upgrade. The new headworks facility included screening and aerated grit removal and influent design for the force main/pressure sewer from the two towns and mountain resort. The treatment process was an SBR facility with tertiary filtration and UV disinfection for phosphorus removal.
Tata & Howard, Inc. prepared a Water System Operations Plan for the Falmouth water system. As part of the Settlement Agreement between the Town of Falmouth and the Commonwealth of Massachusetts, the Town agreed to complete a Water System Operations Plan. The purpose of the plan was to evaluate seasonal demands, current source and storage tank operations and identify system and operational changes necessary to address distribution areas with low chlorine residuals.
The Town of Falmouth’s water distribution system consists of approximately 400 miles of water mains of various materials ranging in size from six to 24 inches in diameter. The Town has five active water supply sources including both groundwater and a currently unfiltered surface supply. Each source is treated with sodium hypochlorite for disinfection with the exception of Long Pond, which includes disinfection with chlorine gas. Falmouth’s water distribution system includes four water storage tanks and a Supervisory Control and Data Acquisition (SCADA) system to run and monitor operations.
The Falmouth Water Department faced a number of challenges, including the following:
Maintaining regulatory compliance
Meeting water demands
Peak summer demands could only be met with Long Pond surface supply
Long Pond is an unfiltered surface water supply
Constant struggle to maintain treatment compliance and water quality
Seasonal impacts from turnover or algae growth
Lack of treatment to address taste, odor, and color can require severe curtailment in use of the supply
Excessive source chlorine residuals needed to maintain distribution system residual chlorine concentrations, combined with source water organics results in elevated disinfection by-products (DBP – Total Trihalomethanes and Haloacetic Acids) which are regulated compounds
The study reviewed the challenges above and recommended changes to systems operations procedures to improve water quality. We used a hydraulic model to determine water age and look at its impacts on water quality. The plan was submitted and approved by Mass DEP.
Additionally, Tata & Howard completed the design of a 3.6 mgd treatment facility which utilizes air stripping and pressure filtration technology for the removal of iron, manganese and volatile organic compounds (VOCs). The facility includes an air stripping tower, three greensand filtration units, horizontal carbon contactors, chemical storage and feed facilities, gravel pack supply well, finished water storage, and backwash holding tanks.
The Town of Canton had primarily been relying on water from the Massachusetts Water Resources Authority (MWRA) for a majority of its water supply needs since 2003 due to the poor water quality of their well supplies. In order to reduce the amount of water purchased from MWRA, the Town began investigations of water treatment options for iron and manganese removal. In 2005, Tata & Howard conducted a pilot test using water from Well No. 9 since it represented what was considered the worst water quality particularly with regard to iron concentration. The pilot testing indicated that oxidation with potassium permanganate followed by membrane ultrafiltration would be successful in reducing the elevated levels of iron and manganese to below the Secondary Maximum Contaminant Levels of 0.3 mg/l and 0.05 mg/l, respectively. Based on the results of preliminary pilot testing, a system from Koch Membrane Systems, Inc. (Koch) of Wilmington, Massachusetts was used.
In addition to the pilot study, Tata & Howard performed a feasibility study to determine the best location for a treatment facility for all of their well supplies. The recommended location for a single facility was a Town-owned property between Charles Drive and Pecunit Street adjacent to the Well Nos. 11 and 12 site, requiring the construction of approximately 14,500-feet of transmission main. Due to the significant cost of the transmission mains, the disruption of traffic throughout the Town from road excavation for construction of those mains, and the unknown cost of the required permitting activities for the transmission mains, the Town decided on the construction of two treatment facilities.
Tata & Howard provided engineering design and construction administration services for two water treatment facilities. Piloting for the projects was completed at two well sites. The Neponset Street Water Treatment Facility (WTF) has a design capacity of 2.53 mgd. The facility use ultrafiltration with chlorine dioxide for treatment. The Pecunit Street WTF has a design capacity of 0.95 mgd and uses LayneOx with chlorination for treatment. The two treatment facilities allowed the Town to reduce the volume of water purchased by the MWRA.
Tata & Howard completed the design of a 3.6 mgd water treatment facility which utilizes air stripping and pressure filtration technology for the removal of iron, manganese and volatile organic compounds (VOCs). The facility includes an air stripping tower, three greensand filtration units, horizontal carbon contactors, chemical storage and feed facilities, gravel pack supply well, finished water storage, and backwash holding tanks.
Let's stay in touch.
Get the latest news, blogs, and insights conveniently in your inbox.
The plant included numerous sustainability and energy efficiency initiatives including the following:
