Bronx and Manhattan Grit Chambers

The Wards Island Water Pollution Control Plant’s Bronx and Manhattan Grit Chambers are central components of the New York City Department of Environmental Protection’s (DEP) wastewater treatment operations. Constructed in the 1930s, the Grit Chambers handle millions of gallons of sewage each day, 365 days a year.

Over the years, from non-stop use and exposure to the elements, many of the masonry surfaces on each building had begun to deteriorate and required restoration and repointing. In addition, to accommodate changing environmental regulatory demands, it became necessary to rethink the plant’s processing systems and power supply systems. After carefully examining their options, the New Your City DEP embarked on a comprehensive upgrade and restoration initiative.

Working in concert Frontier-Kemper Constructors, Inc., Durr Mechanical Construction, Perini Corporation, and Hazen and Sawyer, Graciano began work on the project, which involved construction of several new structures, additions to existing facilities, and restoration of exterior and interior surfaces on the landmark buildings. New structures include housings for two electrical substations and a froth-control building. Additions to existing buildings include a new boiler house facility and a residual handling building.

Graciano’s responsibilities on the assignment included general masonry restoration, cleaning and repair, extensive reconstruction of parapets, resetting of coping materials, and replacement of several three-story windows that were installed when the buildings were built nearly 70 years ago. The assignment also entailed matching of bond patterns, colors and textures, installation of pre-cast lintels — including complex circular lintels that will border several sets of round louvers, and replacement of damaged structural glazed facing tiles that line the interior of the buildings.

Project Details

Completion Date: 9/22/2005
Owner: New York City Department of Environmental Protection
Architect: Malcolm Pirnie
Engineer: Frontier-Kemper Constructors, Inc., Hazen and Sawyer, Durr Mechanical Construction, Perini Corporation

Project Included

  • Water Control Injections
  • Unit Stone Replacement
  • Terra Cotta
  • Structural Steel Repair/Replacement
  • Stonework
  • Stone Patching
  • Repointing Masonry
  • Replacement
  • Repair
  • Pressure Washing
  • Partial Depth Concrete Repair
  • Parapet & Coping Reconstruction
  • Paint Removal
  • New Brick Construction
  • Masonry Surface Rehabilitation
  • Masonry Cleaning
  • Lintel Replacement
  • Individual Brick Replacement
  • Dutchman Repair
  • Deck Coatings
  • Concrete Restoration
  • Chemical Cleaning
  • Brickwork
  • Brick Facade Rebuild
  • Alkaline Cleaners
  • Acidic Cleaners

Glossary Terms

Tuck PointingTuck pointing entails removing loose or cracked mortar from brickwork or stone installations and replacing its new mortar to ensure structural integrity and to seal out damaging water and moisture. Mortar for tuck pointing must be carefully selected to ensure that its color and texture of the new mortar closely matches the existing material that was not compromised and did not need to be removed. ShotcreteShotcrete is a material that combines concrete with compressed air. The mixture is pumped through a hose at high pressure, and is then applied to the desired surface. The force of the air pressure consolidates the material on the surface. Shotcrete can be formulated in one of two ways. The wet method premixes the concrete with water before it is pumped through the high–pressure hose. The dry method involves sucking the dry materials into the application system, combining them with water within the hose, and then apply them to the final surface. Masonry RestorationMasonry restoration involves the repair of existing masonry materials or the complete replacement of damaged materials with new or reclaimed bricks or stones. Color and texture matching are key considerations in masonry restoration, as an accurate match can make areas of restored stone or brick blend in seamlessly with existing materials. To achieve an accurate color and texture match, it is frequently necessary to return to the original brick manufacturer for replacements, or to the original stone quarry where material for the existing stone components was cut. GroutingGrouting is used to seal the spaces between masonry installations such as tile or terra cotta. Grout may be colored to blend with the masonry materials, or can be used to create contrast within the masonry design. Grout is typically applied by hand by filling the joints with material and then troweling it out over the adjoining tile or terra cotta. Once the grout has set, a craftsman returns to the area that was grouted and removes any excess material from the face of the installation. As grout is frequently porous, it must be sealed once it is completely dry to protect it from dirt infiltration. DemolitionDemolition entails the removal of damaged or undesired concrete. It is most frequently accomplished with a jackhammer or another piece of pneumatic equipment. CaulkingCaulking is used to seal gaps between masonry surfaces, such as brick or stone, and other architectural elements, including window and door frames, decorative hardware or lighting fixtures. Caulking is most often applied with a gun, and is available in butyl, latex or customized formulations. The color of caulk is selected to match the surfaces surrounding the application site. When applied, the caulking gun is inserted in the gap to be filled. Caulking material is then injected into the void to seal the opening.