Location: New Haven, Connecticut
Owner: Connecticut Department of Transportation
Client: Connecticut Department of Transportation
Construction Cost: $20,000,000
- Utility Engineering
Under its I-95 New Haven Harbor Crossing Corridor Improvement Program, the Connecticut Department of Transportation (ConnDOT) is effecting extensive multi-modal transportation improvements along 7.2 miles of I-95. The signature component of this program is the construction of a new Pearl Harbor Memorial (Q) Bridge. The new, 4,600-foot, 23-span structure will carry 10 lanes of I-95 traffic over the Quinnipiac River. The 525-foot main span will be one of the first extradosed, cable-stayed bridges constructed in the US.
Construction of the bridge will rely in large part on the erection of temporary work trestles at various points across the river. The trestle north of the bridge required a pile-supported foundation. The foundation would directly conflict with existing sanitary sewer force mains beneath the harbor. The twin force mains in question, owned and operated by the Greater New Haven Water Pollution Control Authority, are therefore being relocated prior to the commencement of the main bridge construction.
Lochner has been selected to provide construction management services for this $20 million sanitary sewer relocation. In this role, Lochner is overseeing all aspects of the construction operation. Two new, 42-inch pipes, each approximately 1,800 feet in length, are being installed beneath the harbor, north of the bridge construction site. To minimize environmental impacts to the Quinnipiac River, horizontal directional drilling is being used to install the new pipes beneath the riverbed. Drilling begins with the establishment of a pilot hole, six inches in diameter. This is incrementally increased through a number of reaming passes until it reaches the 60 inches required for pipe installation. A considerable challenge for the drilling operations in this project is that the pipes must be placed on a sharply curved alignment.
Once the reaming process is complete, the two high-density polyethylene pipes will be installed. The pipes are each comprised of four 450-foot sections. Each section will be fusion-welded to the preceding section, pressure tested, and documented with a video camera inspection before being pulled through the shaft. The pipes will be connected at both ends to the main sanitary system’s ductile iron pipes. Once the new force mains are in full operation, the existing pipes will be filled and abandoned.
Throughout the drilling operations, a major consideration for both Lochner and the contractor has been the minimization of impacts to the Quinnipiac River. Horizontal directional drilling requires that a mixture of mud, water, and bentonite be pumped into the hole to maintain its shape. It is key to Lochner’s inspection role to ensure that the chance of this material making its way through fissures to the river bottom, and contaminating the waterway, is minimized by regulating the pumping speed.
This 16-month project is scheduled for completion in spring 2009.