WESTFIELD – The Conservation Commission voted last week to continue its review of improvements at the North Elm/Notre Dame intersection because of concern about the quality of stormwater being collected and channeled into the Westfield River.
The commission requested the city, through its engineering consultant, Vanasse Hangen Brustlin (VHB) of Watertown, to provide details of facilities being incorporated into the project to improve the stormwater prior to its discharge into the Westfield River.
The intersection improvements include widening the pavement to create dedicated left turn lanes on North Elm Street in both directions, and widening of the throat of the upper section of Notre Dame Street at the intersection.
The project also includes creation of a parking area to replace existing parking at Mestek Inc., which is being taken to widen the road for the new turning lanes.
The project will increase the area of pavement by more than 23,000 square-feet, roughly half an acre and that additional area of impervious surface will result in greater runoff of storm water.
Gene Crouch of VHB said the existing storm drains along North Elm Street south of the intersection and upper Notre Dame Street west of the intersection will be replaced with deep-sump basins which are designed to capture sediment contained in storm water.
Crouch and Amanda Bazinet of VHB, said that the topography and the need to flow water toward the Westfield River limit stormwater collection and treatment, but that stormwater collected from the new parking area will be filtered through a vegetated rain garden to remove sediment.
Drainage is a major element of the intersection improvement project because that area is subject to frequent flooding. VHB has proposed to plug a storm pipe between Powder Mill Brook and the intersection because when the level of the brook rises during storm events, water flows from the brook into the intersection, causing flooding as it comes up through storm drains.
Capping that pipe will stop the backflow of water, but the drainage system must be reoriented to allow stormwater to flow south toward the Westfield River instead of north toward the brook.
The commission requested details of the stormwater treatment, including the rain garden, to be presented before it closes its review and renders its conditions for the project.
City Engineer Mark Cressotti had requested that the commission close its hearing and that the information be provided at a later date to allow the city to move forward with advertizing and awarding the project as soon as possible.
“The city would like to advertise the project within three weeks,” Cressotti said at the Feb. 10 meeting. Typically projects put out for bid at the beginning of the year receive higher level of interest, and most competitive cost bids, by contractors seeking to line up work for the approaching construction season.
