Replacement of the Paines Hill Tank was listed as the highest priority action item and is still the Town’s first priority. (Plan section 8.3.1.) Active storage volume is a function of the height of the water tanks. The tanks all need to be the same height eventually because they function together as a single system, and the system is only as effective as its lowest tank. Increases in tank height also require improvements in pumping to lift water to the new, higher, elevation. As it happens, the main pump station is also due for an upgrade. It is a fortuitous coincidence that the pumping system needs to be replaced at the same time the Town needs to raise its tank elevations.
After replacing the tanks and making some smaller, localized water system investments, the Plan’s next priority is to add a second, redundant, connection to the Massachusetts Water Resources Authority (MWRA), the source of the Town’s water. We should note that the MWRA pipeline has not had any reported breaks and appears to be in good condition. In the unlikely event that the MWRA connection fails, the MWRA, working with the Town, has the capacity to remedy any breakdown within a very short time, likely within hours or at most a day. The MWRA has initiated a process to coordinate with Weston and the Town of Wellesley regarding the secondary line, and the Town is taking preliminary steps to address the issue of the redundant pipe. The recommendation for a second MWRA line is for contingency purposes only and is thus has a lower priority than increasing the active storage in our tanks. Our ability to provide water and fire protection, and to protect houses and businesses, is more important than the addition of a redundant pipe to back up an existing pipe that shows no signs of imminent failure. We have plenty of water; what we lack is the storage capacity to use it.
We have been asked whether adding a second feed main from the MWRA that would operate in parallel with the existing pipe, and adding a fourth pump to the pumping station, would increase the water system’s reliability and capacity. The answer is that it would not, because the Town’s existing pump station has adequate pump capacity now, and pumping alone cannot remedy the lack of storage capacity; only additional water tank height can do that.