Canaan, VT and Stewartstown, NH Energy Efficient Wastewater Treatment Plant Upgrades

The Towns of Canaan, Vermont and Stewartstown, New Hampshire operate a shared wastewater treatment facility, which required significant upgrades. The existing facilities were 40 years old and although a few upgrades were performed in the 90s, the facilities were not performing well, did not meet Life Safety codes, and required significant maintenance. The upgrade met all of the goals of the Client by providing for simple operation and maintenance requirements, meeting the Life Safety codes, eliminating confined spaces, lowering of electrical power costs, and meeting discharge parameters through production of high quality effluent. The solutions developed for the upgrade to this facility were also economical.

Control building insulated concrete forms

One of the primary elements of the design was the consideration of the economics of energy reduction.  The design incorporated insulated concrete form construction for the building walls with R-49 insulation rating in the ceilings.  The design also included a wood pellet boiler with a pellet silo and hot water heating system, which allowed for reduction of explosion proof heaters in the headworks building.  All of the windows were low-E and highly insulated, and an outer glassed-in entry way increased the solar gain retention of the building and reduced heat loss.  The process headworks and operations buildings were constructed as single story structures, increasing operator safety.  The lagoon aeration system is now a fine bubble, highly efficient process with additional mixing provided by solar powered mixers that help reduce aeration requirements, improve treatment, and allows for the addition of septage, all at no cost due to solar power.  The pump station upgrades were designed to eliminate daily confined space entry by the operator by the conversion to submersible pumps.  For sludge removal, a unique and simple “Sludge Sled” system was incorporated, which allows the operators to easily remove the sludge at their convenience. Sludge treatment is accomplished with a geo-bag system that allows the sludge to be freeze dried, reducing the volume by almost 50% with no energy consumption. The influent pump station was designed with three pumps instead of the normal two-pump system in order to meet both present and future design flows, allow for lower horsepower pumps, improve flexibility, reduce replacement costs, and reduce energy costs.   The other four deep dry pit pump stations were converted to wet wells and submersible pumps, eliminating confined spaces, and are equipped with emergency generators, eliminating the need for operator attention when power is lost.

Solar mixers for lagoons

The incorporation of highly energy efficient building components resulted in reducing annual operation and maintenance costs, which resulted in lower user rates and a more sustainable facility.  All building components are virtually maintenance free.  All of the equipment and processes were selected to reduce both annual and future replacement costs.

The treatment system is a 3-cell aerated lagoon system, and the solar powered mixers were installed to enable reduction of the aeration needs and horsepower during the summer months when septage is added.  The aeration blowers, which are housed in insulated enclosures, reduce noise and were sized to allow for the addition of septage to the lagoons, which is not common in Vermont.  The aeration blowers are controlled with Variable Frequency Drives (VFDs), which allow for greater operator control of aeration and provide energy cost savings. The operation is simple and safe for operators and others who need to maintain the facility and equipment.  The design has provided flexibility to the operators and has resulted in an energy efficient, sustainable solution for this community.

 

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Ozone Water Treatment Plant in Franklin, MA

Tata & Howard provided design and construction services for a new water treatment facility that houses a 1.2 mgd ultrafiltration system and completed a pilot test that consisted of an evaluation of two separate ultrafiltration technologies.  Franklin Wells No. 1 and 2, located off Hayward Street in Franklin, Massachusetts were installed in the 1940’s with a combined safe yield of 1.2 million gallons per day. Due to high concentrations of iron and manganese in the groundwater, the wells were only used to meet peak water demands during the summer months. The construction of the water treatment facility recaptures the yield from these two sources.  The water treatment facility consists of a main building which houses static mixers, ozone feed equipment, chemical feed equipment, prefilters, membrane filtration equipment, instrumentation and controls. Treatment consists of ozone oxidation followed by membrane ultrafiltration. The project was funded in part by the Massachusetts Water Pollution Abatement Trust through a low interest state revolving fund loan.

The overall treatment scheme is as follows: ozone injection, oxidation of iron and manganese in an ozone contact tank, prefiltration, treatment through two ultrafiltration membrane skids, chlorination prior to a clearwell, and fluoride addition prior to discharge into the distribution system. The plant is designed to recycle backwash water and membrane recirculation water to the head of the plant utilizing two decant tanks. Ozone is produced on site utilizing compressed air, while a LOX tank is available to allow for the production of additional ozone if required in the future.

 

Pilot Testing for Iron and Manganese Removal in Barnstable, MA

Pilot testing includes carbon, Greensand, and LayneOx filters

Due to elevated levels of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), 1,4 Dioxane, and iron and manganese in the three drinking water production wells at the Maher Water Treatment Facility, the Town of Barnstable is proceeding with design and construction of upgrades at the facility to treat for these constituents.   The Town of Barnstable is currently conducting pilot testing at the site to determine the required design parameters, treatment process effectiveness, and best technology to achieve the desired treated water.  Treatment processes associated with pilot testing include GreensandPlus and LayneOx for removal of iron and manganese, advanced oxidation (ultraviolet light with hydrogen peroxide) for removal of 1,4-dioxane, and granular activated carbon (GAC) for removal of PFOS and PFOA.  Treatment for 1,4 Dioxane is the primary goal of the pilot test in order to meet the requirements of the Massachusetts Department of Environmental Protection (MassDEP) New Technology Approval process.  The MassDEP has confirmed that pilot testing of GAC filtration at the Maher facility is not a statutory requirement due to the current use of this water treatment technology at the Town’s Mary Dunn Wells and the availability of current water quality data for treatment of PFOS/PFOA within the same water system.  However, the Town has decided to include GAC filtration with pilot testing of advanced oxidation and iron and manganese removal to evaluate the performance of all proposed treatment processes operating together.

UV reactor for pilot test

Pilot testing is being conducted by Blueleaf, Inc. as a sub-consultant to Tata & Howard, Inc.  Pilot testing is scheduled for completion in September 2017.

 

Funding Assistance for WWTF Upgrade in Lyndon, VT

Upgrade for a 750,000 gallon per day extended aeration wastewater treatment facility to an A/O biological facility.  Assistance included acquiring State CWSRF planning grants and USDA Rural Development grant for extensive improvements including separation of combined sewer/stormwater collection systems (CSO), advanced Class A sludge treatment, and reconstruction of original 1970’s treatment facility to new Anoxic/Oxic Treatment System.  Total grant funds were $7,275,000.

Water Treatment Plant in Concord, MA

This project included construction of a 1.5 mgd capacity water treatment facility to treat potable water pumped from the existing Deaconess Well.  The water treatment facility consisted of six vertical LayneOx pressure filters.  The work also included demolition of the existing well pumping station and construction of a well pump vault with vertical turbine pump over the existing well, and completion of a SCADA system design to monitor and control the water treatment facility and well station.

Background:

Faced with increasing iron and manganese concentrations at two of its existing wells, Concord Public Works (CPW) decided that treatment was required.  Several treatment options were evaluated, with the most cost effective option being pressure filtration.  Piloting pitted manganese greensand against LayneOx, a proprietary media marketed by Layne-Christensen Company utilized in other parts of the country, but not in New England.  In addition to proving its effectiveness in iron and manganese removal, “new technology approval” was obtained for the media from MassDEP.  Although piloting showed LayneOx to have an advantage over greensand during testing at the Deaconess well site, the Town’s Procurement Office was reluctant to allow CPW to solely specify a proprietary media.  Differences in piping and chemical requirements for both filter processes precluded a design that could have served either treatment system.  Hence, a pre-purchase equipment bid was developed specifying both systems.

An additional challenge to treating the water was designing the treatment facility itself, whose architecture had to “blend in” with the bucolic and well healed character of the surrounding neighborhood.  The Town requested that we provide three options simulating different themes; a barn, railroad station and a Richardsonian Romanesque style structure similar to the Chestnut Hill pump station.  Our Architect provided renderings of the three options along with estimated costs and lists of pros and cons.  After several meetings and input from various interested parties the Town chose the barn theme.

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Water Treatment Plant in North Chelmsford, MA

Tata & Howard completed a test evaluation and design report for the Bomil Well site comparing ultrafiltration using ozone and chlorine dioxide as oxidants.  The report also evaluated several coagulant aids to treat the organic color in the water.  The design report became the basis for the 2.5 mgd water treatment facility designed by Tata & Howard.  The facility uses membrane filtration with chlorine dioxide for treatment.  Construction administration was also provided by Tata & Howard.

Iron and Manganese Removal Using Greensand Pressure Filtration

Greensand tanks at the James J. McKeon Water Treatment Facility in North Attleboro, MA

Tata & Howard conducted a Water Quality Study that reviewed the Town of North Attleboro, Massachusett’s corrosion control practices, and evaluated changes in quality, specifically the increased levels of iron and manganese. The manganese concentrations in these wells had consistently increased during the past decade. The pilot treatment study for manganese removal with greensand pressure filtration was conducted at the Kelley Wells 1 and 2 and was a success. Tata & Howard completed the design of the 2.0 mgd capacity treatment facility and provided engineering services during the construction of the facility.

The design included the installation of a SCADA system for monitoring and control of the treatment facility and two well pump stations.  A second operator work station was installed at the remote Water Department office which allowed both monitoring and control of the treatment facilities from this remote site.  In addition, the operator work station was linked to the existing Autocon SCADA system which continued to monitor and control the remaining water system pumping stations and storage tanks and provide tank level signals for the establishment of start/stop setpoint controls for the new treatment facility and associated wells.

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Trinity Ave. Chemical Feed Pump Station, Grafton, MA

Tata & Howard provided engineering services for permitting, design, and bidding of the 1.3 mgd chemical injection Trinity Avenue Pump Station at the Trinity Avenue Wellfield.  The project included an evaluation of alternatives for the access road including installation of a bridge or an open bottomed culvert; assistance with the preparation of permanent easements for the installation of utilities and roadway to the well site; preparation and submittal of an NOI to the Grafton Conservation Commission.  The design included an access road, bailey bridge with abutments, double wythe block building, interior concrete painted block with wood truss roof and asphaltic shingles, installation of three (3) submersible pumps and pitless adaptors, approximately 1,800 linear feet of 6-inch and 12-inch water main, emergency liquid propane tanks and generator, instrumentation and controls, a SCADA system for the pump station and wells, and a 24-inch transmission main for 4-log removal. Security included chain link fence, gates, locks, intrusion alarms, and lighting.  Tata & Howard also assisted Owner 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 project is currently under construction and is expected to be completed by the end of 2017.

Manganese Filtration Using Biological Pressure Filtration

The Home Farm Water Treatment Plant (WTP) in Shrewsbury, Massachusetts was originally constructed in 1989. Although the WTP is still fully functional, its treatment capabilities are limited to chemical addition and air strippers for VOC removal, and the plant is capable of treating 6.0 million gallons per day (mgd). Manganese is present at all Home Farm wells, with widely varying levels from a low 0.03 parts per million (ppm) to a high 0.7 ppm. The existing treatment plant sequesters manganese, but does not have the ability to remove it from finished water.

Three treatment methodologies were piloted. The first two were greensand and pyrolucite, both commonly implemented catalytic media options for removing manganese and iron. The third was Mangazur®, a new technology. Mangazur® filter media contains the microscopic organism leptothrix ochracea, which consumes manganese and is naturally occurring in groundwater. Through consumption, the microbes oxidize the manganese to a state where it can precipitate onto the media. Unlike other media, Mangazur® does not require regeneration due to the continuous growth of microbes within the filter. Mangazur® technology also does not require chemical addition for pre-oxidation, minimizing the amount of chemical required for the plant.

Pilot testing for the biological treatment was performed over five one-week trials. Test parameters included a long shut-down on the filters, adding pre-oxidant, and adjusting pH or dissolved oxygen. The results of the testing indicated that although the Mangazur® does require a correct dissolved oxygen level and pH, it does not require a pre-oxidant, making the only chemical addition necessary for pretreatment potassium hydroxide for pH adjustment. Filter backwash efficiency is also a major benefit of the Mangazur® technology for the Home Farm application. With loading rates twice that of traditional catalytic media and filter runs exceeding 96 hours; the Town would only need to backwash the four filters once every four days rather than eight filters every day, saving a significant amount of water. The backwash flow rate and duration are also significantly lower for Mangazur® filters than for other traditional filter options. The results of the pilot tests indicated that all technologies were viable options to reduce manganese levels below 0.05 ppm; however, the biological treatment was the most efficient and attractive option.

Initially, the Town was only considering constructing filters along with the required backwash holding tanks in a new building and utilizing the chemical feed systems in the existing treatment facility. However, as the project progressed it was determined that it would be more cost effective to replace the existing aging air strippers rather than to continue to rehabilitate them, and eliminate the need to re-pipe the flow since the existing strippers added too much dissolved oxygen prior to the biological units. Since the existing chemical feed equipment in the plant is aging and the existing building itself was also in need of rehabilitation, the decision was made to construct an entirely new standalone 7.0 mgd facility. The new facility also contains three deep bubble aerators for VOC removal.

While Mangazur® technology has been approved in one other municipality in Massachusetts, there are few treatment plants in the northeast using this technology, and of those treatment plants, none have a design capacity above 5.0 mgd.  Home Farm has a much higher design capacity and will be the largest Mangazur® water treatment plant in the northeast once completed.  The Mangazur® filters at Home Farm will have the second highest design capacity in the country, after a 26.0 mgd treatment plant in Lake Havasu City, Arizona.


 

 

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Water Treatment Facility, Water Mains, and River Crossing Horizontal Directional Drilling

directional-drillingTata & Howard provided design and construction services for the construction of a 1.44 mgd water treatment facility.  The water treatment facility consists of a concrete block masonry building housing filtration equipment, a laboratory and office space, and associated piping, instrumentation and controls. Building components including HVAC, plumbing, and electrical services were incorporated in the facility. Other work included, but is not necessarily limited to, site work, exterior piping systems, and electrical work at an existing well pump station.

rock-drill-rigTata & Howard also provided design and construction services for the installation of approximately 5,000 linear feet of new 12-inch high-density polyethylene (HDPE) water main (two parallel pipes at 2,500 linear feet, each) via directional drilling beneath the Pemigewasset River, connecting the City’s Franklin Falls Well Site and the City’s Acme Well Site.

Tata & Howard provided design and construction services for the installation of approximately 2,655 linear feet of 12-inch diameter Class 52 ductile iron water main, water services, and associated valves, fittings, and hydrants on Hill Road (New Hampshire Route 3A) and a service road connecting Hill Road to the City’s Acme Well site; approximately 4,000 linear feet of 12-inch water main, water services, and associated valves, fittings, and hydrants on Lawndale Avenue, Webster Lake Road, and Kimball Street; approximately 3,200 linear feet along Lawndale Avenue; 1,200 linear feet along Webster Lake Road; and 600 linear feet along Kimball Street.  The work also included pavement restoration on Lawndale Avenue, Webster Lake Road, and Kimball Street.

The project was funded by NHDES and the USDA Rural Development office.