A buried stream rises again
WILLIAMSTOWN - The increasing frequency of storms like the ones in May that damaged roads and private property in Williamstown and North Adams indicate a significant change in local weather patterns. Many New England towns are now struggling to replace drainage structures that in many cases were built according to 100-year-flood models that are no longer practical.
According to a draft of the Federal Advisory Committee's 2013 Climate Assessment Report, "The Northeast has experienced a greater increase in extreme precipitation over the past few decades than any other region in the U.S.; between 1958 and 2010, the Northeast saw a 74 percent increase in the amount of precipitation falling in very heavy events."
In South Williamstown, culverts along a tributary of Hemlock Brook were washed away during a storm on May 29, when debris became lodged in their openings, creating dams that the water burst through. In the downtown area, flooding from the area around Christmas Brook, which runs through Taconic Golf Course and along Weston Field, has been an ongoing problem for the last several years.
An extensive renovation project at Weston Field (the Williams College playing fields) on Latham Street will likely begin next fall and include a reconfigured drainage system that will help diminish runoff into the brook, but the flooding will most likely continue.
One of the main
During heavy rains, the water may back up, rushing down Latham Street toward the Green River, as it did on May 29, flooding the basements of houses on Meacham Street.
Paul Lovegreen, whose basement has flooded five times since 2005, said that between 1999 - when he moved onto Meacham Street - and 2005, flooding had not been an issue. He said the problem is runoff from Weston Field and from other nearby developments that overwhelms the culvert.
In 2005, the construction of Renzie Lamb Field (an artificial-turf lacrosse field near the brook) was completed, increasing runoff into the brook during storms and possibly contributing to the increased flooding.
The 680-acre Christmas Brook watershed includes Stone Hill and the Clark Art Institute, the area around Buxton School, Taconic Golf Course, Weston Field, Spring Street and Hoxsey Street. "That whole acreage feeds into this one little creek that turns into a swelling, raging river," Lovegreen said. "And you only have that little tiny hole that the water can get through."
In the last few years, the entrance to the concrete culvert had begun to crumble, said Philip McKnight, chairman of the Conservation Commission. The town and the college brought a proposal to the commission to repair the culvert, he said, "and we gave them that permission. But unfortunately it didn't solve the issue of the smaller pipe" closer to Latham Street.
Last February the DPW collected 11 bids to replace the culvert entrance entirely and it has since settled on Clayton Davenport Excavating in Greenfield as the contractor. According to the Williamstown website, "The project includes installation of a new precast concrete box culvert, headwall, wingwall, connections to existing structures, riprap [large-diameter gravel], sewer replacement and removal and resetting of existing fencing, guardrails, curbing, sidewalk, and pavement."
But the 800-foot pipe will remain in place. Although the DPW maintains the culvert underneath Latham Street, most of the pipe is on college property (Water Street is owned by the state). Kaiser said replacing the pipe would probably require the town's involvement, but it would ultimately be the college's responsibility.
"The town is doing the portion that it is responsible for, under Latham Street," Kaiser said.
The Weston Field project will not include changes to the culvert, said Jason Moran, the project manager, but it will likely decrease the amount of runoff that enters Christmas Brook. Renzie Lamb Field will be moved farther east, he said, and the student parking lot near Latham Street will return to grass. Both of those areas lie within 100 feet of the brook and are within the Conservation Commission's jurisdiction.
State regulations require that post-development runoff for renovation projects be equal to or less than pre-development levels, said Moran. But it will be nearly impossible to know in the end whether the flows are exactly the same. "So normally what you do is you err on side of caution and you make it slightly better," he said.
"The intent of the new site design is to keep every component as far away from Christmas Brook as feasibly possible while still satisfying other jurisdictions such as the Planning Board [and] the Zoning Board rules and regulations," he said.
Because of the project's complexity, the Conservation Commission requested on May 23 that that an independent company conduct its own assessment of the Weston Field drainage system. A site visit took place Tuesday, June 11. On Thursday, June 27, the commission will again look at the proposal.
Although the plans include the construction of a road running from Latham Street through the project site and connecting to Meacham Street, there will still be an overall increase in ground permeability, said McKnight. That might reduce the frequency of flooding, but not eliminate it altogether.
"Again, when you have hundred-year storms, not a lot of improvement helps because there is just so much water," McKnight said. "But it will be an improvement because of the addition of those two pervious surfaces in the resource area."
Another concern is the risk of flooding on the 1.3-acre site of the old Town Garage on Water Street, which is one of the primary sites being considered for future affordable housing. On May 29, floodwater from the Christmas Brook watershed ran through the southern portion of the site. The Affordable Housing Committee has indicated that any proposal for development at the site will need to take the risk of flooding into account.
In 2011 the loss of most of the homes at The Spruces Mobile Home Park during Tropical Storm Irene greatly increased the town's need for elderly and low-income housing. Of the several potential sites the town is considering for new development, the Water Street site is the furthest along in terms of gaining town approval and finding a developer.
The Affordable Housing Committee, the DPW, the Conservation Commission and the potential developer would all need to be involved in efforts to control flooding at the site, McKnight said. As the pipe's owner, the college may also become involved.
Any correction of the culvert problem, "ought to be done before housing or expansion of the business district or whatever use of the old Town Garage site," is decided on, McKnight said. "It ought to be part and parcel to that."
The section of Christmas Brook that flows underground may turn out not to be within the jurisdiction of the Conservation Commission, since it is not considered free flowing, but portions of the Water Street site are within the 200-foot buffer zone surrounding the Green River. "So we would be involved with any project to build on the Town Garage site," McKnight said. "And maybe we would ask at that point to try to resolve this problem."