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LaGuardia Airport / 81st St. and 19th Ave: Engineering Inspection of Combined Sewer Outfall
Prime-consultant REI for the reconstruction of a combined sewer outfall to Bowery Bay — verified defect-free with a LiDAR-equipped drone.
Project facts
| Client / owner | NYC Department of Design and Construction |
|---|---|
| Location | Queens, NY |
| Role | Prime consultant |
| Budget (as published) | $7.3M |
| Disciplines | Drones / Robotics / UAVs · Resident Engineering Inspection |
Overview
As a prime consultant, Gedeon GRC Consulting provided resident engineering inspection services for the reconstruction and replacement of an existing sewer and outfall discharging into Bowery Bay. The project addressed a partially collapsed outfall — restoring its necessary functions and preventing full collapse — through the installation of a new 14-foot 7-inch-wide by 8-foot-high combined sewer outfall at the same location, using a temporary bypass within an existing easement on City-owned land under the jurisdiction of the Department of Small Business Services.
Engineering approach
The sewer and outfall design calls for a reinforced concrete structure supported on a concrete cradle on piles, with a flap gate at the outlet to control any inflow of tidal water from the bay. Boulders were installed to stabilize the bottom of the bay, minimizing the potential for scour and resuspension of sediments into the water column when there is flow from the outfall. Additional scope included pavement, utilities, installation of a cofferdam, and coordination with NYSDEC, NYCDEP, NYCDOT and PANYNJ.
Drone-verified as-built assessment
To support post-construction inspection, Gedeon GRC flew the Elios 3 with Survey LiDAR into the combined sewer outfall to perform an as-built assessment — collecting 4K video of the culvert within the project limits and generating a LiDAR point cloud from which confirmatory measurements could be extracted. The point cloud and video data were processed in Inspector 4.0, where conditions and potential concerns could be referenced directly within the point cloud. Each point of interest carries a relative location accurate within 4 inches per 100 feet, providing a reliable method for locating any construction deficiencies. After review of the flight data, the project was confirmed to be defect free.
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