Tata & Howard prepared a sequential Unidirectional Flushing Plan (UDF) for the Town of Wayland’s water distribution system, utilizing the existing hydraulic model to develop flushing sequences for hydrants and valves to be operated. The sequences were updated from the original plan to review anticipated flushing velocities and identify areas of potential low-pressure concerns. Field assistance was provided during the implementation of the updated plan. A summary report was provided, identifying the amount of water used during flushing, areas of hydrant or valve mapping discrepancies, and areas with broken or inoperable hydrants and valves.
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 conducted energy efficiency studies for the City of Flagstaff on their water and wastewater systems. Initial testing showed that modifications to these systems had the potential to save the City approximately $350,000 in annual electrical costs and $445,000 in Arizona Public Power System (APS) rebates if systems were modified with newer technology and upgraded. Pumping systems had efficiencies as low as 5.2% and the wastewater blowers as low as 19.5% where efficiencies of greater than 65% are attainable. Energy usage on the wastewater treatment side per million gallons treated showed 2,170 KWH/MG with cogeneration and 2,804 KWH/MG at the Rio plant. The national average usage is 1,750 KWH/MG. Much of the equipment was oversized to meet peak and future demands but was not efficient at low flows or off-peak flows.
From this study and evaluation, the City retained Tata & Howard to provide design and construction administration services for replacing the existing aeration blowers at the Rio De Flag Water Reclamation Plant (WRP). Design services included the layout of the new screw compressors in the existing aeration room, as well as associated electrical, air intake and new piping to the existing aeration basins. The project was completed in December 2017; APS provided a rebate of $83,000 and preliminary annual power savings of roughly $73,200.
On the water system, the review included most of the wells, pressure reducing valves, boosters, and zone splits for energy savings. To date, eight (8) facilities have been upgraded, resulting in $256,000 in APS rebates and two of the facilities resulting in $109,000 of annual power costs. The other facilities have not been calculated. The total for both the water and wastewater systems has resulted in $490,000 in APS rebates and power costs savings of greater than $198,000 with additional projects available to extend these numbers. In addition to the power savings and rebates; operations, and reliability of the facilities have improved, and staff has an increased knowledge and awareness of power costs.
The Town of Falmouth retained Tata & Howard to remediate lead-contaminated soil associated with historical firing range activities at a former gravel pit owned by the Town. Due to the gravel pit’s location within a current drinking water source area, the objective of the remediation was to restore the release to background and remove the potential threat to the underlying groundwater quality. In addition, the presence of estimated habitats of rare wildlife and priority habitats of rare species at the gravel pit required the filing of a Notice of Intent (NOI) with the Conservation Commission and implementing measures to protect the rare wildlife and species. Tata & Howard prepared a site-specific scope of work for bidding purposes and managed all the field activities. Part of the remedial action plan was to screen the soil in an effort to remove the lead bullets and facilitate disposal of the contaminated soil at a Massachusetts lined landfill. Analytical testing of the soil revealed that some areas contained leachable lead, which required stabilization with Portland cement prior to being transported to the landfill. During the excavation activities, Tata & Howard utilized a field portable x-ray fluorescence (XRF) analyzer to obtain real-time concentrations of lead in soil. Use of the XRF minimized contractor down time because decisions relative to the extent of excavation required could be made in the field. Confirmatory laboratory analytical results correlated well with the XRF data. Tata & Howard prepared a Permanent Solution with No Conditions Statement, which documents that a condition of No Significant Risk has been achieved at the Site and that the release conditions have been restored to background.
Tata & Howard completed a Business Practice Evaluation (BPE) for the Town of Framingham, MA. T&H coordinated and attended a project kick-off meeting with essential Town personnel. The Town provided, as available, documents requested at the Project Kick-off meeting including reports, CIP and operating budgets, organization charts, standard operating procedures, operation and maintenance reports, O&M manuals, performance measures, job descriptions, Emergency Response Plan, procurement process, inventory control, relevant studies and reports, and similar related documents. These documents were used both for assessment of the current practices and as documentation included in the written plan, as appropriate. Evaluations determined the adequacy of the documents and current business practices. Documents were compiled and organized electronically for use in the project and future use by the Town. Any critical missing information was identified and developed by Town staff or included as part of the Implementation Plan.