• Context 

The North River Water Resource Recovery Facility (the Facility) is a 28‐acre facility located at 135th Street & 12th Avenue in the west side of Manhattan. North River is an alternative name for the southernmost portion of the Hudson River in the vicinity of New York City and northeastern New Jersey in the United States. The construction of the facility started in early 1970s and completed in 1982. The Facility is designed to treat up to 170 million gallons per day of Dry Weather Flow (DWF) and 340 million gallons per day of Wet Weather Flow (WWF). The Facility has been in operation since the completion of construction in the 1980’s. Adding to the uniqueness of the facility was the addition on the roof, the Riverbank State Park. The facility is a vital component of the New York City Department of Environmental Protection’s (DEP) wastewater treatment infrastructure. 

• Technical and Environmental Challenge 

The facility is comprised of several structures separated by expansion joints. The roof slab is mostly composed of precast pre-stressed or post-tensioned hollow core concrete planks supported on structural steel or reinforced concrete framing. Most of the structure below the roof is composed of reinforced concrete beams, columns, walls and slabs. Over a mile of expansion joints traverse each level of the facility along similar planes allowing movement throughout the structure. Clogged drains and lack of maintenance have caused pooling on top of the protective roof slab deteriorating the existing roof expansion joints and damaging equipment and structural members below. The environmental challenge from a leaking facility is the potential water pollution to the Hudson River that is located right below the plant in operation. 

• Long-term Solution in Progress 

In early 2017, NYC DEP issued request for proposals for design services for North River Wastewater Treatment Plant (NRWWTP) Structural Improvement Project. Thornton Tomasetti, Inc. has been assigned as the architectural/engineering consultant for assessing and developing design documents for the repair and replacement of the expansion joints located throughout the various levels of the NRWWTP. The procedure of assessing the expansion joint has started with existing document review, non-destructive examination, and physical testing, which involves probing of the expansion joints. The purpose of the probing is to expose the roof deck level expansion joints that are the true first line of defense against water infiltration from above at the building structure, and gather further information from where most superficial defects are identified at the park level, and at the intersections of the expansion joints where workmanship is the most critical and usually fail first. The roof deck expansion joint system is typically hidden below the final park finish materials, which include; concrete roadway paving, landscape paving, soil within planters, athletic fields and courts, etc. The physical testing also involves flood testing and material laboratory testing.