Water Storage Tanks
Weston & Sampson provides evaluation, design and construction of a variety of storage tank types, including concrete, steel, and Aquastore.
As one example, to comply with a consent order from the Department of Environmental Protection (DEP), the Massachusetts Water Resources Authority (MWRA) provided 25 million gallons of covered distribution storage at the location of the existing Nash Hill Reservoir in Ludlow, Massachusetts. MWRA hired Weston & Sampson to evaluate covered storage alternatives and complete the preliminary design of the selected alternative. The evaluation portion of the project included consideration of 17 alternatives for covered storage facilities with the selection of seven alternatives for further study. Following approval of the seven alternatives, we recommended one alternative with two back-up alternatives.
The alternatives included variations of the following five technologies:
A dual basin cast-in-place concrete tank
- Two prestressed concrete tanks
- Two steel tanks
- A floating cover with a new dividing wall
- A precast concrete fixed cover with a new dividing wall
Weston & Sampson used the following criteria to further evaluate the seven covered storage design alternatives.
- Safe Drinking Water Act (SDWA) Compliance
- Ease of operation and maintenance
- Environmental impacts
- Capital and life-cycle costs
Based on the above criteria, we developed and selected the most favored alternative for providing covered distribution storage. The cast-in-place tank, prestressed concrete tanks, and steel tanks were all very comparable in life cycle cost and other rated criteria. The least costly alternative was the floating cover, while the fixed cover proved to be the most costly.
The other major portion of this project was the consideration of five alternatives for maintaining service to the three effected communities during construction. The alternatives were based upon the partial or complete isolation of the Nash Hill Reservoir from the transmission system during the construction of improvements. Weston & Sampson completed the preliminary design of the MWRA’s most favored alternative, dual 12.5 million gallon prestressed concrete tanks with flat column supported roofs.