Bay Park Conveyance Project

Innovative Design-Build Project to Improve Water Quality on Long Island

The Bay Park Conveyance Project is a partnership between the New York State Department of Environmental Conservation and the Nassau County Department of Public Works to improve water quality and spur ecological recovery in Long Island’s Western Bays.

Currently, excessive nitrogen and poor overall water quality in the Western Bays are negatively impacting the environmental and economic vitality of the region, as well as the quality of life for residents. The poor water quality has led to algal blooms and decreased aquatic life, notably shellfish, further impacting the local economy. Additionally, the poor water quality can lead to degradation of plant life and the coastal marsh islands, which serve as a natural barrier to storm surge and waves.

To combat this, the Bay Park Conveyance Project was conceived to reduce nitrogen pollution into the Western Bays by redirecting treated water from the South Shore Water Reclamation Facility to the Cedar Creek Water Pollution Control Plant. There, the treated effluent can be released 3 miles offshore via an existing ocean outfall diffusion pipe system.

The Bay Park Conveyance Project comprises 3.6 miles of new forcemain built by microtunneling, as well as the slipline rehabilitation of 7.2 miles of existing 100-year-old forcemain under Sunrise Highway. The slipline portion of the project is repurposing an abandoned aqueduct, not used since the 1960s, that was originally used to convey drinking water from Nassau County to New York City.

Related work includes the construction of 14 microtunneling shafts using secant piles, soil mixing and jet grouting, and a new 75-mgd effluent diversion pump station. The entire 11-mile pipeline is 20 to 60 ft deep.

Project elements include:

• A new pump station at the existing South Shore Water Reclamation Facility
• New Force Main:
  • Segment 1: Bay Park to Sunrise Highway Microtunnel – 2 miles
  • Segment 2: Sunrise Highway Aqueduct Sliplining – 7.2 miles
  • Segment 3: Sunrise Highway to Cedar Creek Microtunnel – 1.6 miles
• New pumps and a standpipe receiving tank at the Cedar Creek WPCP
• Connection to the existing Cedar Creek WPCP ocean outfall

AECOM was hired as the owner’s representative. WSP was hired to provide preliminary design and a joint venture of Hazen & Sawyer and Arcadis was hired to provide program management services for Nassau County.

In April 2020, the New York State Department of Environmental Conservation (DEC) and Nassau County issued a request for proposals for the design and construction of the project. Western Bays Constructors (WBC) – consisting of John P. Picone Inc., Northeast Remsco Inc., Delve Underground, and Greeley and Hanson – was selected as the design-build contractor from a pool of three pre-qualified bidders.

The team was chosen based on its best value technical solution, which included the concept of using single-pass fiberglass lined concrete jacking pipe, and the elimination of a shaft location by combining two microtunneling drives into a single, longer curved drive.

Notice to Proceed was issued in March 2021.

Microtunneling
The microtunneling portion of the project was split into two segments: the Bay Park alignment and the Cedar Creek alignment. Over 18,000 ft of 72-in. Flow-Crete pipe from Thompson Pipe was microtunneled between the two locations. This marked the first use of Flow-Crete pipe in the United States, having previously been used in North America on a project in Canada. Flow-Crete is a composite pipe incorporating an outer load-bearing wall of reinforced concrete and an inner fiberglass reinforced liner pipe

The Bay Park alignment consisted of seven drives, totaling 9,810 ft, and eight shafts. The Cedar Creek alignment consisted of five drives, totaling 8,210 ft, and six shafts. The longest drive on the Bay Park alignment was 2,285 ft, which included a 4,800-ft radius curve. The longest drive on the Cedar Creek alignment was 1,936 ft.

Nine of the 12 drives exceeded 1,300 ft in length, leading to the decision to use Intermediate Jacking Stations (IJSs). On long drives, the theoretical jacking loads could exceed the allowable jacking loads of the pipe. The decision to use IJSs overcame this hurdle and mitigated the risk of the pipe getting stuck. At least one IJS was used on each drive and three IJSs were used on the longest drive.

The selection of Flow-Crete pipe was based on performance and installation capabilities. Because Flow-Crete combines the compressive strength of reinforced concrete with the corrosion resistance of fiberglass pipe, it allowed a single pass installation method that meets the stipulated 100-year design life.

Work took place in an active wastewater treatment plant, along the shoulders of busy commercial and residential roads, and adjacent to an offramp of the Sunrise Highway. Considering the busy area and 24-hour-a-day operations, community relations were paramount to success. WBC worked with the community and provided ample notice on schedule, which kept the residents and businesses in the area abreast of the impacts the project would have on the area. Additionally, noise mitigation techniques were used on equipment to reduce impacts.

There was also a requirement on the project that all of the Flow-Crete needed to be on site for the drive before WBC could launch. This created a major challenge in finding storage for the pipe. There was barely enough room for the microtunnel equipment, so the storage of 2,000 plus ft of pipe became a major undertaking. WBC was able to store pipe at dormant shaft locations, along the side of roads, and in rental properties.

The last tunneling drive was finished in November 2023.

Sliplining
To connect the Bay Park Conveyance Project between the two microtunneled portions, an existing approximately 7-mile section of 72-in. abandoned steel aqueduct was rehabilitated and sliplined with 66-in. Thompson Flowtite fiberglass pipe.

Unlike the microtunnel operation, WBC was constrained on the working hours for the slipline operation. The majority of the work took place in pits along the Sunrise Highway, requiring lane closures and traffic detours. As a result, WBC was only allowed to perform sliplining during night hours.

Each evening, WBC was required to set up, mobilize light towers, modify the traffic pattern, remove the precast planks to expose the pit, all before any production work could start. At the end of the shift, the planks were required to be placed back over the pits, and traffic needed to be restored to normal. All of this preparation work resulted in about five hours of production during a 12-hour shift.

For construction, 24 pits were installed throughout the alignment in order to access the aqueduct and install the fiberglass slipline pressure pipe. The aqueduct had various changes in grade and elevation, therefore, two different methods were used to install the FRP pie.

On straight runs, a jacking pipe was used to push the pipe to station. To assist with installation and protection of the FRP joint during the installation of the pipe, TPG provided prefabricated FRP pipe skids on the pipe.

On curves, a carry cart was used to walk the pipe to station. The pits were strategically placed in locations in order to maximize the length of segments that could be jacked. The longest segment of pipe pushed at one time was 2,873 ft. The longest segment of pipe carried in was 1,669 ft.

Conclusion
The $439 million Bay Park Conveyance Project represents one of the largest current trenchless projects in the United States. Its use of alternative delivery methods allowed a flexible work environment for the contractor and engineering teams to realize the end goals, achieve cost savings through alternative technical proposals, and introduce new products that helped increase efficiency.

The new conveyance system is anticipated to be operational in 2025, helping improve water quality and storm resiliency in Long Island’s Western Bays.