Tata & Howard completed an Extended Period Simulation (EPS) hydraulic model of the water distribution system for the Town of Avon, Massachusetts. An EPS model was created to account for changes in the water distribution system over an extended period to include peak and minimum demands during both the summer and winter months. These changes included tank levels, pump controls, value operation, and demand variations.
The EPS model was used to estimate the water age in the water distribution system under winter and summer demand conditions. Water age is the time water takes to travel from a water supply source to a point within the distribution system. It is used as an indicator of water quality based on the assumption that the older the water is, the greater the likelihood that water quality has deteriorated. According to MassDEP Finished Water Storage Guidelines, a three to five-day complete water turnover is recommended in water storage tanks.
The EPS model was also utilized to evaluate the Town’s existing system operations. The model was used to determine the optimal tank operating range and the impact of the run times on the well pumps. Simulations were performed on both the Center Street and Page Street Tanks to evaluate operations under existing and projected average day demand (ADD), maximum day demand (MDD), and peak hour demands with a minimum pressure of 35 psi maintained throughout the distribution system.
In addition to analyzing the tank optimal operating levels, changes to the existing pump operations and the effect on tank levels and water age were evaluated. Two modified pump operations scenarios were evaluated. Both scenarios were run with the existing tank water level controls and allowing the Page Street Tank to drop four feet. A second modified pump operation scenario evaluated the Town’s lead/lag system. Results for the pump and tank level operations under these simulations were recorded for both summer and winter operations.
Based on the results from each operational modification, Tata & Howard made several recommendations for improvement to the water distribution system. These included allowing the water level in the Page Street and Central Street tanks to drop an additional six feet to improve water age during both the summer and winter demands.
In addition, to help improve the water age in the tanks to an optimal three to five-day complete water turnover as recommended by MassDEP Finished Water Storage Guidelines, Tata & Howard suggested installing mixing systems in each tank.
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.
Tata & Howard, Inc. was recently retained by the Town of Manchester-by-the-Sea to complete a Capital Efficiency Plan™ for the Town’s water system. The system was evaluated to identify areas of the water distribution system in need of rehabilitation, repair, or replacement, and to prioritize improvements to make the most efficient use of the Town’s capital budget. The study evaluates the existing water infrastructure including water transmission and distribution piping and appurtenances. In addition, water storage and supply needs were evaluated and prioritized. The analysis and improvements in this report are based on the Three Circles Approach for optimum capital efficiency, which combines hydraulic and critical component considerations with an asset management rating system to evaluate the condition of the water mains in the distribution system. Each circle represents a unique set of evaluation criteria for each water main segment. From each set of criteria, system deficiencies are identified. System deficiencies from each circle are then compared. Any deficiency that falls into more than one circle is given higher priority than one that does not. Using the Three Circle Approach, recommended improvements will result in the most benefit to the system. In addition, the Three Circle Approach allows us to identify any situations that mitigate a deficiency in one circle and eliminate a deficiency in another circle. By integrating all three sets of criteria, the infrastructure improvement decision making process and overall capital efficiency are optimized.
Recommendations included a siting study for a second storage tank, Phase I-III distribution system improvements, and the continuance of scheduled maintenance programs such as hydrant flushing, leak detection, and meter testing. The Town’s pavement management plan was also taken into consideration to best prioritize and coordinate utility work with roadway reconstruction.
A Capital Efficiency Plan™ was completed for the Town of Rowley in May 2017. The study evaluated the 45 miles of the Town’s water distribution system using the Three Circles Approach, which consists of a system hydraulic evaluation, criticality component assessment, and asset management considerations. From each set of criteria, system deficiencies were identified and a 20-year recommended improvements plan was provided. Recommended improvements consisted of water main replacement projects, a pumping capacity evaluation and well redevelopment study, an interconnection analysis, and a distribution static pressure evaluation.
A critical component assessment was performed for the water distribution system to evaluate the impact of potential water main failures on the system. The critical component assessment includes identification of critical areas served, critical water mains, and the need for redundant mains. Critical areas served were identified by the FDWD and include water department facilities, medical facilities, schools, and business districts. Critical water mains include primary transmission lines as well as water mains that cross over major highways, rivers, and railroad tracks. Factors that affected the decision to replace or rehabilitate a water main include break history, material, age, diameter, soil conditions, water quality, and pressure.
Tata & Howard, Inc. was retained by the City of Attleboro to complete a Capital Efficiency Plan™ and Water System Master Plan for the Attleboro water system. The purpose of the Capital Efficiency Plan™ portion of the project was to identify areas of the water distribution system in need of rehabilitation, repair, or replacement, and to prioritize improvements to make the most efficient use of the City’s capital budget. The Water System Master Plan portion of the project created an inventory of the existing above ground water infrastructure assets including wells, pumping and treatment facilities, and water storage tanks. The inventory can be used to track maintenance, repair, and replacement work. Basin safe yields were reviewed and compared to projected demands to evaluate the adequacy of sources of supply. In addition, the project included creation of an extended period simulation (EPS) hydraulic model which can be used to analyze the system and account for changes over time.
An asset management assessment was completed for the system. Several factors are considered in the assessment including age, material, diameter, break history, soil conditions, water quality, pressure, and whether the main was installed poorly. These factors affect the decision to replace or rehabilitate a water main. Using our asset management rating approach, each water main in the system was assigned a rating based on these factors. Utilizing the