Services: Treatment

Water Treatment Plant Dissolved Air Flotation (DAF) Pilot Study, Norwich, CT

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The NPU contracted with Tata & Howard for the design and construction of renovations at the Stony Brook Water Treatment Plant. The NPU was challenged by an apparent and relatively abrupt change in raw water quality as a result of a green algae bloom consisting primarily of chlorophyta beginning in the summer of 2010. The original project requested the replacement of the media in the filter clarifier units with buoyant media. T&H proposed an alternative approach to not replace the media but rather add a new unit operation to the plant. Our belief was that simply changing the media at this plant would not have appreciably changed the treated water quality. T&H recently completed piloting a Dissolved Air Flotation (DAF) system at the plant to improve treated water quality.

Tata & Howard prepared a pilot test plan for DAF Clarifier piloting at the Stony Brook Water Treatment Plant site and conducted one summer season of DAF clarifier and filtration piloting. A pilot study report was prepared,  including water quality data, evaluation of the treatment system, chemical dosages, flow rates, conclusions, recommended process, and design criteria. As a part of the pilot study, bench scale testing was performed to examine the performance of coagulants and polymers at various dosages and mix rates for the best removal of disinfection by-product (DBP) precursors. The bench scale testing was performed simultaneously with the pilot test and results were incorporated into the pilot test program.

In addition, T&H prepared design drawings and specifications for a 4.0 mgd capacity DAF clarifier system to be added to the plant to remove algae and to remove a greater level of disinfection by-product precursors. Additionally, we assisted with bidding of the project and provided construction administration and resident observation services.

DAF Water Treatment Facility Construction and Startup

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Tata & Howard provided construction administration, resident observation, and start-up services to the Milford Water Company for the construction of the Dilla Street DAF 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 replaced the existing slow-sand and diatomaceous earth (DE) treatment previously 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.

Distribution System Water Quality Study, Norwich, CT

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Tata & Howard, Inc. was retained by the Norwich Public Utilities (NPU) in Norwich, Connecticut to perform a distribution system water quality study to evaluate the water age, water quality, and hydraulic gradient in the Taftville/Occum Service Area. The Taftville/Occum Service Area has high water age, due primarily to the large volume of the Occum Tank.  In addition, high levels of total trihalomethanes (TTHM) are observed throughout the Taftville/Occum Service Area.

This study examined the TTHM concentrations and high water age in the Taftville/Occum Service Area and presents various options to help mitigate these issues.

During the course of this study the following tasks were completed:

  • Updated the existing WaterGEMS hydraulic model using recent system data
  • Collected water distribution system data on current operating conditions,
    historical and current disinfection by-product samples, water age, pressures, flows, and tank levels and supply and demand data for the entire NPU system
  • Conducted a gradient evaluation of the affected service area and investigated potential alternatives to improve the current conditions, including making short and long term capital improvements to provide improved tank level fluctuation and improved customer pressure ranges
  • Performed water age modeling of the existing service area and for potential
    alternatives that improve the current conditions and graphed the results
  • Provided information and costs for alternatives to the tank passive mixing system
  • Provided recommendations for improving the service area gradient(s), water age, and water quality
  • To evaluate the Taftville/Occum Service Area, the entire NPU distribution system needed to be examined to determine the quality of the water as it enters the service area.

The key finding from this study related to the TTHM levels in the Taftville/Occum Service Area was that the formation potential in the effluent water from both of NPU’s surface water treatment plants was high enough for the TTHMs to exceed 80 µg/L at the entry point to the service area.

Based on this study, NPU has decided to add dissolved air flotation (DAF) to its Stony Brook water treatment plant. Tata & Howard designed the DAF system and other related improvements.

District Water Treatment Facility, Transmission Mains, and Metering Station, Mattapoisett, MA

MRVWD_water treatment facility

The MRVWD water treatment facility project was designed to treat water from eight wells belonging to the Towns of Fairhaven, Marion and Mattapoisett.  The MRVWD facilities also include approximately 5 miles of raw water transmission mains between the wells and the water treatment facility, finished water transmission mains from the water treatment facility to the existing town transmission mains, six new 100 HP high lift pumps and control/metering stations. The existing pump stations were upgraded to pump water to the water treatment facility but operation of the pump stations will remain the responsibility of the individual towns.

The total cost of all project components was approximately $16.5 million, which was partially funded with a low interest SRF loan. By constructing a regional facility, the towns were able to save over $4.9 million in design and construction costs in comparison to individual treatment facilities.

On-Call Water Engineering Services, Franklin, NH

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Tata & Howard has been assisting the City of Franklin, New Hampshire with general water engineering services since 2009. The Tata & Howard team has managed several phases of work, including the design and construction of the water treatment plant and distribution system improvements.

The first phase was the design and construction of 2,500 linear feet of water main on Hill Road to connect a new water treatment plant to the City’s distribution system.  This project also involved use of four bioretention systems to treat and manage stormwater from the roadway, and was constructed in 2010.

The second phase of our work with the City included the design and construction of two parallel 2,500 LF sections of 12-inch diameter HDPE crossings beneath the Pemigewasset River using horizontal directional drilling to transport water from the City’s Franklin Falls Well to the water treatment plant site.

Tata & Howard managed the survey and geophysical studies and prepared a Preliminary Design Report and Environmental Review documents for several phases of work.  The City’s wells are surrounded by lands controlled by the US Army Corps of Engineers, which required that we complete an extensive permitting process to secure permissions for the final design of the project.

Tata & Howard completed design, construction, permitting, and funding applications for a 1,000 gallons per minute groundwater treatment plant to remove iron and manganese from three of the City’s wells. The plant has four pressure filters containing Greensand Plus media and using sodium hypochlorite for oxidation and sodium carbonate (soda ash) for pH adjustment. This plant went online July 9, 2012.

Tata & Howard provided design services for the construction of a new prestressed concrete tank at the site of an existing tank. The existing tank was in poor condition and due to the site characteristics, it was determined that construction of the new tank on the existing foundation of the old tank would be the best option.  A second tank on the site was demolished in 2013 and a new prestressed concrete tank will be constructed in its place.

Tata & Howard also conducted a full water system analysis for the City of Franklin, New Hampshire by utilizing our proprietary Capital Efficiency Plan™ methodology.  Our CEP involved creating a model of all water infrastructure in the City including sources, pump stations, treatment facilities, storage facilities, transmission, and distribution lines. Using our GIS modeling software, the system was calibrated based on fire flows in an attempt to accurately replicate the existing system. We then pinpointed deficiencies within the system based on a custom rating scale given to multiple criteria such as age, break history, material type, criticality and size. Recommendations were made for improvements in order of need. The study renewed both above ground and below ground assets. Funding for this study was in part from an Asset Management Planning Grant from NHDES.

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Energy Efficiency Study, Flagstaff, AZ

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Tata & Howard conducted an energy efficiency study on the aeration blowers and pumps at the Rio and Wildcat Hill treatment plants. The testing showed that modifications to these systems have the potential to save the City approximately $250,000 in annual electrical costs and $445,000 in APS rebate funds for the modifications. Pumping systems had efficiencies as low as 20%. Pumps and blowers were oversized to meet peak and future demands but not efficient at low flows or off peak flows. Energy usage per million gallons treated of 2,170 KWH/MG with cogeneration and 2,804 KWH/MG at the Rio plant, with national average usage of 1,750 KWH/MG.

The project included the testing of blowers and pumps at two reclaimed water plants; review of all the wells, pressure reducing valves, boosters, and splits for energy savings; further evaluation of the turbo blowers and barscreens; and an evaluation of the replacement of the biogas piping for use in cogeneration.

Presentation:

Abstract: In Arizona, the Arizona Public Service (APS) estimates that water systems use 1/7th of all the power used in the State. From the APS testing program, it is estimated that 60 to 70 percent of all pumps have tested below industry standards or changes in operations are needed to operate more efficient. This presentation discusses the findings associated with energy studies completed for a small water supply system (Kachina Village Improvement District) and for a large system (City of Flagstaff, Arizona). The studies show that any water and/or wastewater system, regardless of size can benefit from an energy audit. The studies resulted in significant annual savings, potential rebates from APS to offset replacement costs, high return on investments, while promoting green initiatives.

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Onsite Wastewater Treatment Facility, Hopkinton, MA

Private Sector — Legacy Farms

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Tata & Howard provided design and construction administration services associated with expansion of the Legacy Farms private wastewater treatment facility and effluent disposal areas.

The project assisted in moving from 115,000 gallons per day (gpd) to 190,000 gpd, which consists of the installation of additional membrane cassettes to increase the capacity from 115,000 gpd to 150,000 gpd, installation of additional membrane modules, installation of mechanical equipment fully redundant at a maximum daily flow of 190,000 gpd, permitting assistance with MassDEP, and the construction of two additional effluent disposal areas. Construction of the first of two new effluent disposal areas is underway, and T&H Project Engineer and Certified Soil Evaluator Matt Barry was recently on-site to conduct a perc test for the second effluent disposal area.

Original Project

HopkintonMA_LegacyFarms_layoutTata & Howard provided soil investigation and evaluation, preliminary design, and design services for an onsite wastewater treatment facility and disposal system to serve the proposed Legacy Farms mixed-use development in Hopkinton, Massachusetts.

The Legacy Farms development includes a retail village, a commercial district, a variety of residential spaces (apartments, town homes, single-family homes, and multi-family structures) on approximately 733 acres currently used for nursery and agricultural uses. Approximately 940 new dwellings, 450,000 square feet of retail and commercial space, and 500 acres of restored open space will be made available by the project.

Tata & Howard’s services have included development of treatment flows for the full, built-out project, as well as selection and design of the wastewater pumping treatment and disposal systems that were compatible for the site configuration and soils, and that would provide the level of treatment required by the Massachusetts Department of Environmental Protection (MassDEP).  The challenge was satisfied by the design for a phased approach to the construction of a membrane bioreactor (MBR) treatment system, which provides a high level of treatment.

The project includes three submersible pump stations that serve the wastewater treatment facility (influent, recirculation, and effluent disposal) and two submersible pump stations within the development itself.

Disposal of treated effluent at the Legacy Farms site will be managed by a combination of conventional leaching systems and an innovative use of drip irrigation, the first large-scale application of drip irrigation for disposal of treated effluent in the State of Massachusetts.

The success of this project was related to excellent communication between Tata & Howard and the client, and a strong working relationship with MassDEP.

Pump Station Design and Wastewater Treatment Facility Upgrades, Barre, MA

Barre wastewater treatment facility

The Town of Barre retained Tata & Howard to evaluate their existing wastewater treatment facility. Tata & Howard recommended a three phase upgrade program in order to reduce the initial impact of the construction cost on the sewer use rates. Included in the upgrade program was the design and construction of a submersible pump station that lifts the raw wastewater from an equalization tank to the biological treatment process. The pump station has a capacity of 1.2 mgd and includes variable frequency drives. The pumping station is controlled by a new SCADA system at the wastewater treatment facility. Tata & Howard also designed 8,000 linear feet of collection system sewers in the Worcester Road area of town. The project also included 500 linear feet of force main and a wet well mounted pump station. The pump station has a capacity of 200 gpm.

Wastewater Pump Stations and Treatment Plant, Canaan, VT

Canaan VT aerial

Tata & Howard provided engineering services for the evaluation, permitting, design, and construction of five wastewater pump stations. The pump stations included a new triplex pump station with valve structure. The wastewater treatment plant upgrade was in addition to the pump stations. The other four pump stations consisted of a new, completely relocated pump station and the upgrading of three other dry pit wet pit stations to include generators and controls for telemetry. The pump station design included a plan for maintaining operations of the stations throughout construction, which was completed in the fall of 2014.

Wastewater Treatment Facility Design, Upgrades, Bid, and Construction Administration, Dexter, ME

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Tata & Howard team members provided engineering services to The Dexter Utility District to evaluate their existing wastewater treatment facility and to provide wastewater treatment facility design. It was recommended that a phased approach to upgrade the facility be utilized in order to reduce the initial impact on the sewer user rates.

The first phase of the improvements combined improvements which would improve the reliability and obtain energy savings with cleaning and disposing of sludge for the first time from their 25 year old facility. This approach allowed for a grant loan financing package to be utilized. The first phase facility upgrade included replacing a leaking single air header main with two individual air headers, replacing course bubble diffusers with fine bubble membrane diffusers, replacing three 25 year old blowers with new blowers with variable speed drives. The speed of the new blowers is controlled by a PID loop using dissolved oxygen analyzers, to maintain optimum treatment and minimize energy consumption. These improvements have reduced the energy consumption at the wastewater treatment facility by more than 50 percent.

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