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NYC Regulator Chamber Replacement and Hobas Non-Circular Slip Lining Rehabilitation

By: Sal Leopoldo, Halcyon Construction Corporation

History

Sewage Regulator Chamber HP06 is located within the Borough of Bronx, New York City. Regulator Chamber and Interceptor Sewer Piping were built in the 1940s for the City of New York Public Works as part of the Hunts Point Sewage Treatment Plant and Intercepting Sewer project. The Chamber is an underground, cast-in-place concrete structure approximately 28 feet wide x 46 feet long x 35 feet deep located under busy New York City Streets.

During normal dry weather conditions, the regulator directs up to 60MGD of flow to 700lf of cast-in-place 8 feet wide x 7 feet high interceptor sewer at depths up to 25 feet. Wet weather flow surges to over 600MGD and is discharged through twin 12 x 8 foot & 13 x 9 foot CSO sewers.

Upon various inspections, the owner NYCDEP & NYCDDC determined both Regulator Chamber HP06 and 700 feet of 8 feet wide x 7 feet high interceptor sewer was extensively structurally deteriorated due to high concentrations of Hydrogen Sulfide gas and age. In December 2021 Halcyon Construction Corporation was low bidder at $52,372,095.00 for NYCDDC contract REGHP06 to perform open cut replacement of Regulator HP06 and Slip-Line rehabilitation of this 700 foot section of interceptor sewer using HOBAS non-circular pipe.

Mass Excavation Plan

All work was to be performed with no interruption of existing flows.

Commencement Of Work

Site mobilization commenced in August 2022. Halcyon Construction combined construction phases and performed one 125 feet long x 100 feet wide x 25 to 35 feet deep mass excavation of approximately 12,000 cubic yards that would enable

  • Relocation of 30-inch RCP combined sewers.
  • Demolition & Replacement of cast-in- place concrete Regulator Chamber HP06.
  • Installation of temporary twin 8-foot steel welded wet weather flow gravity by-pass piping.
  • Installation of temporary 8 x 7 foot cast-in-place concrete dry weather flow gravity by-pass piping.
  • Expose and remove top roof slab of existing 8 x 7 foot interceptor sewer to enable access and insertion of HOBAS non-circular slip line pipe.
Mass Excavation – Installation of Wet & Dry Weather Gravity By-Pass
Existing 8 x 7-foot 1940s cast-in-place Interceptor Sewer to be HOBAS Slip-Lined

Support of excavation (SOE) included 30 steel drilled piles with 4-inch thick wood lagging, 12 tiebacks along with 4-inch vertical wood sheeting over existing sewers supported by 14-inch steel welded truss walers & braces tied to 6 x 6 x 3 foot concrete thrust restraint blocks.

Read the full case history here.