Precast was determined equal to the job when the New Jersey Department of Transportation (NJDOT) decided to realign Route 21 — a major feeder freeway serving tens of thousands of commuters heading in and out of New York City, Newark Liberty International Airport, and I-95 — to improve traffic flow and safety. Part of the project included replacing the aging (circa 1920) Newark brick combined sewer. In view of the high water table combined with the expensive costs of sheeting and dewatering, Project Engineer Dominic Salsa of general contractor J.H. Reid was motivated to propose an alternative precast solution, a first for NJDOT. Upon obtaining the agency's approval, Salsa contacted Farmingdale, N.J.-based Garden State Precast to help fulfill the challenging project requirements.

Located approximately 45 miles from the job site, Garden State Precast is a NJDOT-approved plant that holds National Precast Concrete Association certification. After over 200 hours of engineering work, 15 structures with unit weights approaching 250,000 lb. were designed. To support the work, major project requirements included flexible rubber seals for 84-in. prestressed pipe, doghouse units for redirecting existing sewers, and reversible sewage flows.

“The sheer size of these units required careful planning and coordination,” reports Bruce Jamison, project manager for Garden State Precast. Members of 12- and 15-in. thickness combined with an 11-ft. 9-in. base height presented significant production and shipping challenges. The large base height was a major factor due to the 100-in. outside diameter of the 84-in. pipe. Adding further complexity, the units needed to be installed directly alongside the Passaic River at a depth of 10 ft. to 20 ft. below the surface level.

Garden State Precast coordinated efforts with various suppliers to propose a workable solution. A.L. Patterson provided technical support in selecting a lifting system to ensure safety and proper rigging of all units. As a cost-efficient method for steam curing the units, A.L. Patterson also fabricated a large insulated curing cover for the project.

Flexible, watertight, cast-in Star Seals measuring 84 in. and 66 in. were custom designed by Bill Jones and manufactured by Warminster, Pa.-based Hail Mary Rubber Co. Tight manufacturing tolerances were maintained in the production of both seals and the large steel hole formers, ensuring adequate compression of the Star Seal to provide watertightness.

Led by Supervisor Mike Vergona, the 11-man production team constructed approximately one unit per week using Western Form handset aluminum panels to produce the units. Again, with some concrete pours in excess of 30 yd., extreme care was taken to maintain project tolerances. All riser sections were match cast on top of the base section to effect a perfect, matched joint for both the four- and five-sided units. Vigorous quality control inspection of each section ensured consistent project tolerances and layouts. Pouring was accomplished with the aid of two 2-yd. E Z Grout Precast Hogs, allowing safe, rapid placement of concrete with minimum spillage. Pour lengths averaged less than one hour for most units.

Several last-minute changes due to site conditions were addressed during production. Some sewers and building foundations were located only by excavation since there were no complete records of existing utilities. As these revisions were handled with on-site inspection of existing conditions, Garden State Precast provided an onsite supervisor to help coordinate proper unit offloading and installation. Communication was thereby enhanced during all phases of the precast operation to keep the job running smoothly.

In addition to handling all route reconnaissance and special permits, Hisko Trucking provided three heavy lowboy trucks as well as escorts for shipment. Each structure was transported whole, with all pieces shipping at the same time. Hisko Trucking demonstrated considerable flexibility, loading some units the previous night, while others were loaded the day of shipment.

In spite of the many challenges encountered, Garden State Precast was able to complete the job to the satisfaction of both J.H. Reid and NJDOT. Each unit was installed in only two days due to careful coordination by the producer — in marked contrast to a minimum timeframe of 12 to 15 days for a cast-in-place unit. The efficiency of precast combined with the enhanced worker safety it provided made precast pipe the solution of choice for New Jersey's sewer replacement problem.
— Information provided by Paul Heidt, general manager, Garden State Precast, 732/938-4436.