Winchester Flood Control Project

After residents of Winchester, Mass., began noticing flooding problems at Manchester Field, the town’s primary athletic grounds, an evaluation by AECOM found that the existing storm water system was too small to handle even the lightest rains. In other words, an upgrade was sorely needed.

The ultimate goal would be to reduce the surcharge of catch basins and manholes, which in turn would alleviate flooding at the field. The new system also would have to withstand any amount of rain up to the infamous “25-year, 24-hour” storm event.

When discussing possible solutions, the project team determined there was not enough space for an aboveground water detention solution. This meant moving the entire system underground. Town officials eventually decided to install a new storm water detention system, produced by Cultec Inc., in two phases. Phase I would see the system installed beneath the onsite basketball courts.

Before the installation team could get to work, however, they discovered that the existing drainage system flowed through a siphon that cut directly across the main sewer line from the Massachusetts Water Resource Authority. The siphon was removed and replaced with a new siphon—10 ft into the groundwater with pipe-jacking techniques—which required significant dewatering. Once that was completed, Cultec began installing its 18.5-in.-high Recharger 150HD underground storage chambers. A total of 1,356 units were employed in Phase I.

The other half of the new storm water system was installed beneath the teachers’ parking lot at McCall Middle School.