The Town of Billerica, MA, situated along the stressed Concord and Shawsheen Rivers, knew it needed to undertake significant sewer system improvements due to compounding regulatory, economic, and environmental drivers. By taking a holistic view of the issues, Billerica developed a program, based on a Comprehensive Wastewater Management Plan, that included treatment plant upgrades, collection system rehab, pump station overhauls, and major sewer extension projects. Together these efforts strengthen the Town’s infrastructure to better protect the environment and serve residents now and in the future.
TREATMENT PLANT UPGRADE MEETS RESTRICTIVE PERMIT LIMITS
After conducting a comprehensive plant evaluation, Woodard & Curran and Billerica planned and implemented treatment system upgrades to meet a new NPDES permit with a low seasonal effluent phosphorus limit of 0.2 mg/l, and significantly lower limits expected in the future. Tertiary treatment upgrades, solids management, process optimization, and SCADA implementation modernized the plant and improved overall performance significantly.
PUMP STATION OVERHAULS PROVIDE CAPACITY FOR EXPANSION
Billerica’s CWMP called for phased improvements to the Town’s 25 pump stations, beginning with the two most critical. These upgrades represent a complete renewal of the pump station network, and provide increased capacity for significant collection system expansion. New pumps, grinders, and SCADA systems extended the life of the stations and integrated them with the overall controls scheme to give Billerica more control.
SEWER EXTENSIONS PROTECT THE CONCORD RIVER WATERSHED
Small lot sizes, severe soils, and shallow groundwater in areas of the Town meant that it would be difficult or impossible to continue to use on-site disposal as a wastewater solution. To address this challenge, Billerica planned an ambitious series of sewer extension projects. Woodard & Curran designed the expansions to minimize pumping requirements, protect historic sites, and take advantage of existing infrastructure right-of-ways wherever possible. The result is better protection of both the environment and public health in areas where replacing on-site disposal systems is not an option.
COLLECTION SYSTEM REHAB LIMITS I/I AND REDUCES PEAK FLOW
Billerica’s collection system consists of two sewer sheds representing 200 miles of pipe. The age of the system, and ongoing issues with wet weather and peak flows made it clear that infiltration/inflow was a problem. Woodard & Curran helped the Town install flow meter and rain and groundwater gauges to determine the source and location of the worst I/I. The project identified 450,000 gallons per day of infiltration and 9 million gallons per day of peak inflow. We then planned and implemented cleaning, sealing, pipe lining, and manhole rehab to reduce I/I and improve wet weather performance.
