STONE HARBOR – Borough Engineer Marc DeBlasio has brought the Borough Council up to date on two flooding studies, on the areas from 80th Street to 88th Street and from 88th Street to 98th Street.
The two studies recommend that, to eliminate flooding in those areas, projects estimated at more than $15 million would be needed, with the borough hoping to pay for them through federal grants.
The purpose of the studies, supported by funding from the Federal Emergency Management Agency, was to identify flood mitigation strategies to reduce or eliminate the nuisance tidal flooding that plagues property owners there.
DeBlasio reminded the council at its March 4 meeting of its acceptance of spring 2022 flood mitigation and storm sewer plans, which now will be updated with the results of the new studies. The combined support from FEMA that funded the studies was $315,000.
The engineer presented data from 2022 and 2024 showing tide elevations and their impact on flooding in the borough. He said the point at which flooding is becoming an increasing problem is at tide elevation 4.5 feet.
He said a survey of bulkhead heights in the two areas showed that property owners are making progress in bringing bulkhead elevations up. “Bulkhead elevations are increasing,” he concluded while comparing recent data to a study done by the Stockton University Coastal Research Center in 2017.
At the time of the Stockton measurements, the borough had 5% of the town’s bulkheads at the ordinance-required elevation of 8 feet. In 2024, DeBlasio said, using the combined areas as a surrogate for the entire borough, the percentage was 12%.
The problem the borough is experiencing, according to the FEMA studies, is coming from tidal flooding backing up into the streets through stormwater outflow piping.
Stone Harbor has been experimenting with various valve configurations at bay-side end streets. The purpose of the valves would be to allow the municipality to stop the flow of water into or out of the bay during tides that would otherwise back up into the streets through the drainage system.
DeBlasio said a “plug valve” would be the instrument of choice and would require manual on/off manipulation based on expected tide levels.
The engineer pointed to the marina area as a significant area of tidal flooding; it is an area where elevation of ramps and bulkheads will be necessary to mitigate flooding, with a protection level up to 4.5 feet of tidal elevation.
The presentation showed mapping of the area from 80th to 88th streets with current levels of flooding eliminated based on the equipment and construction recommendations included in the study, with 4.5 feet of tidal elevation as the target protection level. The price tag DeBlasio put on the effort in this first of the two areas was $8.2 million.
In the second study area, from 88th to 98th streets, the study shows the need for a pump station at 93rd Street. Much of the current planning for flood mitigation turned away from pump station installations in 2022, when one such station under design saw its costs mushroom to more than $20 million.
The firm involved in that planning, Mott MacDonald, was dismissed by the borough, and a search for alternatives began and led to the 2022 flood mitigation plan.
Details on the proposed pump station in the current FEMA study were not discussed, but the potential cost involved in flood mitigation in the second study area was largely driven by the pump station recommendation. DeBlasio estimated the total construction costs of that area’s recommendations at $7.1 million.
DeBlasio said the studies were prelude to the borough’s seeking grant funding for the combined $15.3 million estimate for the two areas. A resolution authorizing the submission of a grant application to FEMA was approved at the meeting.
Contact the reporter, Vince Conti, at vconti@cmcherald.com.
