Due to contamination from Volatile Organic Compounds (VOCs) at two of the Town’s water supply wells, the Town of Natick took steps to construct a water treatment facility to treat the water from the contaminated wells. Tata & Howard conducted a water treatment facility siting evaluation and pilot study; and completed the design of the treatment facility, which utilizes air stripping and pressure filtration technology.
During the course of the design, it was determined that the backwash water would not be permitted by the MWRA to be discharged into the sewer system. Therefore, alternatives needed to be evaluated. One option was to provide holding tanks for the backwash water. This would enable the Town to recycle the supernatant to the head of the facility and therefore, minimize waste of the supply water. Since the area was not conducive for the installation of drying beds, the sludge collected at the bottom of the holding tank was removed by means of a septage hauler.
Tata & Howard proposed to recycle the backwash water, which required DEP approval as it had not been done before in the state. DEP gave approval and now recycled backwash water is used in numerous water treatment facilities in Massachusetts.
PROJECT: Mission critical storage tank systems for Southeast Louisiana Veterans Health Care System (SLVHCS)
SLVHCS in New Orleans, LA
THE CHALLENGE: SLVHCS is the successor to the VA Medical Center, which was decimated by Hurricane Katrina in 2005. The new hospital requirements included green building practices and resiliency during natural disasters, including the ability to remain operational for at least five days with enough provisions and accommodations for up to 1,000 staff and patients in case of a major disaster.
The atrium of SLVHCS
THE SOLUTION: Tata & Howard provided design and construction administration services on specific components of the mission critical storage tanks, which include a domestic water tank, sewage holding tank, cooling tower process and bleed water tank, and fire protection water tank. Our design of specific components of the mission critical tanks included coating, waterproofing, mixing, pumping, bacteria control, odor control, venting, piping to five feet outside the tanks, and instrumentation and control. Specific design elements for resiliency and green design included the following:
Domestic Water Tank system instrumentation/controls include storage tank level measurement and control of inlet/outlet valves. The system also includes ultraviolet disinfection of all potable water pumped from the storage tank into the hospital.
Sewage Holding Tank is waterproof and its control system to provide automated response to an event using electrically actuated valves that direct the sewage from the gravity system to the holding tank. After the event, the system will turn the pumps on and transfer the sewage to the City’s system. A water spray system will automatically wash down the empty tank.
Cooling Tower Make-up Water Tank is waterproof and its control system design provides electrically actuated valves to receive rainwater from the building roof drains, condensate from the buildings, and potable water from the City’s water system. The Cooling Tower Make-up system instrumentation/controls include tank level measurement and control of inlet/outlet valves.
Cooling Tower Bleedwater Tank is waterproof and its control systems design provides electrically actuated valves to accept water from the cooling towers, recycles water to the cooling towers, and pumps it into the municipal sewer system. The Cooling Tower Bleedwater Tank system instrumentation/controls will include tank level measurement and control of inlet/outlet valves.
Fire Protection Water Tank is waterproof and its control system design provides electrically actuated valves to automate control of receipt of water from the CEP/Warehouse roof drains and the City’s water system.
The instrumentation and controls for all of the above elements are capable of communicating with the facility ‘s SCADA system.
PROGRESS: The new state-of-the-art facility opened on August 1, 2015, and the building is on track to receive LEED silver certification. For comprehensive information on the new hospital, please click here.
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:
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During the course of the design, it was determined that the backwash water would not be permitted by the MWRA to be discharged into the sewer system. Therefore, alternatives needed to be evaluated. One option was to provide holding tanks for the backwash water. This would enable the Town to recycle the supernatant to the head of the facility and therefore, minimize waste of the supply water. Since the area was not conducive for the installation of drying beds, the sludge collected at the bottom of the holding tank was removed by means of a septage hauler.
The plant included numerous sustainability and energy efficiency initiatives including the following: