The Massachusetts water Resources Authority (MwRA) wanted to strengthen its water transmission system to ensure that Boston and its surrounding communities could grow and prosper. And they wanted to do it without compromising the quality or reliability of the water supply.

Black & Veatch’s Southern Spine project refers to a portion of the water transmission system that serves the southernmost communities of the metropolitan Boston area. The “spine” is a deep rock tunnel and surface-water transmission main system. Black & Veatch evaluated the condition of large-diameter surface mains. The result was a major rehabilitation and replacement program.

MwRA provides water and sewer service to approximately 2.5 million people in the area. The Southern Spine distribution mains form a network that serves portions of the city of Boston, the city of Quincy and the town of Milton. A portion of the Southern Spine network was constructed at the turn of the 20th century and consists of cast-iron pipe; the remaining portion of the network was constructed in the 1950s using steel pipe.

Upon completion of the pipeline condition assessment and evaluation phase, the project turned to rehabilitating and replacing aging water mains. One contract involved replacement of parallel 24-inch diameter cast-iron water mains with a single, 48-inch ductile iron water main. The new main saves water by eliminating leaks in the aging lines. It also provides a more reliable water supply to the communities served by the mains.

Black & Veatch recommended solutions used innovative assessment processes to determine the condition of the old water mains. Advanced techniques allowed water mains to be rehabilitated rather than replaced. The project also involved the need for extensive negotiation with community groups and business owners. The pipeline design minimized construction impacts to adjacent wetlands and river crossings.