The City of Portland Maine needed to improve two pump stations through reconstruction and upgrades to achieve operational efficiency. The city issued a request for proposals to replace a small pump station in a residential neighborhood and upgrade the city’s largest pump station in a commercial area. They selected Woodard & Curran to provide a 30 percent design with a guaranteed maximum price (GMP) under a progressive design build arrangement. After delivery of the GMP, the city hired Woodard & Curran to oversee the project through construction.
UPGRADING TO TWO VASTLY DIFFERENT PUMP STATIONS
The 700,000 gallon per day (GPD) Curtis Road duplex pump station was slated for elimination from the city’s sewer system, but while performing a Business Case Study, Woodard & Curran identified a comprehensive upgrade was the best approach in considering budgetary impacts, risk, environmental considerations, and societal costs. The pump station, surrounded by shrubbery and with an enclosure barely big enough to stand upright inside, was first installed in the 1980s to pump wastewater from 164 single family homes into a force main driving it approximately 1,000 feet uphill.
Two large diesel pumps were brought in to bypass the wastewater into a temporary force main system, which we operated 24-hours a day. The city allowed a variance so the crew could install the bypass system at night, during the diurnal lows. Woodard & Curran sought input from our in-house and city wastewater operators as the new station was designed to maximize operational efficiency. This included a larger structure so operators could stand upright while inside and easily work around equipment. The addition of a soundproof enclosure also reduced area noise pollution and nuisances for abutting residents.
As work came to an end on Curtis Road, the project team began upgrades to the 3.1 million GPD Franklin Street combined sewer pump station. The Franklin Street station was built in the 1960s and sits on the corner of a busy arterial with nearly 90,000 passing vehicles per hour during peak commuting and is highly visible to area visitors and commercial neighbors. The centrally located facility processes nearly half the city’s peak wastewater flows and was due for upgrades to optimize its operations with the addition of standardized equipment. Woodard & Curran collaborated with city departments to maintain open communication with area businesses, navigate road and nearby trail closures as necessary, and manage public safety.
On Franklin Street, bypass pumping needed to handle up to 6 million gallons per day (MGD), with peak flows of 8 MGD during wet weather events, to allow our team to complete the improvements. During bypass pumping, the grinders were taken out of operation, requiring manual debris management, such as rags and trash that infiltrated the combined system. Wet weather events often necessitated hourly cleaning of debris.
COLLABORATIVE NATURE OF THE DESIGN-BUILD PROCESS
This was the city’s first experience with a design-build approach. Having an existing business relationship, Woodard & Curran worked closely with the city operations and engineering from design through fruition of the upgrades. The city was active in adjusting the design to their specifications and identifying customized inclusions to the new infrastructure.
The city’s preferred network of pre-qualified subcontractors was provided to Woodard & Curran during our bidding process. As subcontractors and vendors were being brought on, Woodard & Curran provided all the financial data to the city, which helped in making informed decisions to adhere to the GMP agreement. As construction progressed, city staff was on site daily making decisions on change orders and other desired design adjustments. City operators were also called in to ensure operational standards were met.