In 1973, a 12-in. ductile iron force main was installed using direct bury methods under the Grand River. Measuring approximately 4,000 ft long, the force main conveyed approximately 1.3 million gallons per day (MGD) of wastewater from the City of Ferrysburg, Spring Lake Township and the Village of Spring Lake to the Grand Haven-Spring Lake Sewer Authority (GHSLSA)Wastewater Treatment Plant. The GHSLSA knew that the force main was reaching its life expectancy and in February 2017, a leak was reported, prompting them to take immediate action to repair and begin design of a replacement pipeline.
In early 2017, the GHSLSA and the Ottawa County Road Commission (acting as the financing agent for the Authority) developed a five-phase project, which included upgrades and improvements to sewer lift stations in Spring Lake, Ferrysburg, and Grand Haven along with headworks upgrades at the treatment plant. The force main installation under the Grand River was Phase 3 of the five-phase contract. The Road Commission hired Prein&Newhof of Muskegon, Michigan, to assess the condition of the existing force main in this critical location. In addition to reviewing options for rehabilitating or replacing the pipe, Prein&Newhof was also hired to analyze the system’s existing capacity and determine any necessary improvements to accommodate increased demand and flow capacity. This review determined that a new pipeline would be needed. This new proposed force main would connect to the pump station in Spring Lake, which will be upgraded in summer 2019, on the north side of the river, and will pump across the river and discharge into the GHSLSA Waste Water Treatment Plant.
Prein&Newhof reviewed multiple pipe alignments and compared trenchless methods with barge supported open cut, or direct bury methods. Due to permitting obstacles, navigation impacts and environmental concerns, the open-cut methods were discarded. Prein&Newhof and the GHSLSA met with horizontal directional drilling (HDD) contractors during design to review feasibility of crossing the Grand River and limitations to the method, such as pipeline assembly and layout, drill staging, vibration, noise issues, access and other impacts to local residents and businesses. Ultimately, HDD was selected as the installation method for the proposed force main, which minimized environmental and navigation impacts and minimized disruption to surrounding communities.
The project was advertised to prospective bidders in November 2018 and was awarded to Gabe’s Construction Co. Inc. of Sheboygan, Wisconsin. Both Fusible PVC pipe (FPVCP) and high-density polyethylene (HDPE) pipe materials were considered for the installation of the new pipe underneath the river. Based on inside diameter requirements and tensile strength, Prein&Newhof determined that 16-in. FPVCP or 22-in. HDPE pipe sections would be required. The HDPE pipe size was required to be larger in nominal diameter so that both pipe cross-sections were equivalent in flow area and long-term pressure carrying capacity.
Gabe’s Construction selected FPVCP for the proposed force main for a number of reasons. The smaller outside diameter of FPVCP resulted in a smaller bore hole, which led to increased production and less disposal. In addition, the tensile strength of the FPVCP pipe was viewed as an important and necessary advantage for this long and deep installation.
Construction began in February 2019. Starting from the north side of the river near the Spring Lake Lift Station, Gabe’s Construction drilled a pilot hole southbound towards Grand Haven utilizing gyroscopic steering methods. Due to the poor soil conditions under the Grand River and to protect against hydrofracture, the depth of the pilot hole ran about 80 to 90 ft beneath the bottom of the river. As a safety precaution, vibration monitors were installed since the project area was in close proximity to residences and businesses. On the south side of the project, the pipe and associated equipment were staged. Due to the length of the pipe installation, the project was staged into five separate lengths or sections of pre-assembled pipe. Each section was approximately 720 ft long, and staged in the road right-of-way.
Gabe’s Construction had to coordinate their schedule with the underground pipe contractor that was installing the force main on each end of the HDD from the pump station and to the wastewater treatment plant. This ensured continuous operation of the existing force main and provided adequate room for the drill operations. The sewer authority secured easements adjacent to the project to allow for additional staging and coordinated the road closure with the City of Grand Haven and adjacent businesses.
Upon completion of pilot bore, Gabe’s made a 26-in. reaming pass followed by a swab pass to complete the boring activities. The 3,887-ft pipe installation commenced at 7 a.m. with a safety briefing. As each 720-ft pipe section was pulled into the conditioned borehole, another 720-ft section was moved from cribbing onto pipe rollers. This next length was then attached to the end of the section that had just been installed with an intermediate fusion joint. This process repeated itself five times to fully assemble the pipe for the crossing while being installed. All six pre-assembled sections were fused together and installed successfully with no disruptions or challenges. Pipe installation was completed before 10 p.m. on the same day. Water ballasting of the pipe, filling the pipe with water to counteract the buoyant forces of the pipe in the borehole which increases drag, was utilized after the third intermediate fusion joint. After installation, on the north side, the pipe was connected to a new force main that was installed from the pump station in Spring Lake. On the south side, the pipe was connected to new a force main to the wastewater treatment plant in Grand Haven. The pipe was pressure tested and ready for operation in April 2019 and put into service in June after completion and acceptance of the entire pipeline.
This highly visible project required coordination of several municipalities and property owners to provide the necessary space for the contractor to complete their operations and provide the system owners with accurate estimates for budgeting. Early communication with those involved and bringing in contractors to review the operations were essential to keeping everyone informed of the schedule and potential impacts from construction. A successful crossing was completed with the efforts of all parties and a new, appropriately sized force main is now in place to serve the residents of the City of Ferrysburg, Spring Lake Township and Village of Spring Lake.