Integrating green and gray infrastructure in the most densely populated city in New England - Stormwater mitigation in Somerville, Massachusetts

Abstract

The City of somerville, Massachusetts, is embarking on major infrastructure upgrades that will change the way it manages much of its combined drainage system. This multifaceted program includes macro improvements to stormwater conveyance, storage, and pumping as well as green stormwater infrastructure incorporated into the public realm and private developments. the somerville Avenue Utility and streetscape improvement (sAUsi) project, one of the first within this program, includes the installation of more than 2,000 lf of 14 by 6 ft (610 m of 4.3 by 1.8 m) precast concrete box culvert, 4,500 lf (1,370 m) of combined and sanitary sewer cast-in-place pipe lining, and a significant incorporation of green infrastructure into the new, “complete” streets design. the new gray infrastructure will provide 860,000 gal (3,255,400 L) of stormwater storage, while the new green infrastructure will provide not only stormwater storage for 1.5 in. (3.81 cm) of runoff from the contributing drainage area but also reduce impervious surfaces, expand the urban forest, and improve the quality of the downstream water bodies.