Greenbriar Flooding Report: 'Historic' Rain Overwhelmed Drains

BRICK, NJ — A historic amount of rain that overwhelmed storm drains is what caused the flooding in Greenbriar 1 during the August 2018 storm, according to a report on an engineering firm's analysis of the storm and its aftermath.

And the flooding would have happened even if the new interchange wasn't in place, the report said.

Brick Township Business Administrator Joanne Bergin shared a summary of the report prepared by French and Parrello Associates, an engineering firm out of Wall hired by Ocean County to look at the flooding that happened in the Aug. 13, 2018 storm. Among the issues they were looking at was whether the changes to the area as a result of the new interchange at 91 contributed to the flooding.

More than 100 homes in Greenbriar 1 had to be evacuated as a result of the storm that dumped nearly 8 inches of rain in a localized area that included parts of Howell and Wall as well as the area right around the Exit 91 interchange in Brick. Parking lots at Evergreen Woods, Primrose Lane and Sutton Village flooded as well.

But Greenbriar 1 bore the brunt of the flooding, with some homes ending up with 4 feet of water destroying furnishings and leaving many residents at a loss as to how to move forward.

Many of those residents expressed concerns that the flooding resulted from changes to the Garden State Parkway in the area, which included a reconfiguration of the exit and entrance ramps and the removal of a number of trees.

French and Parrello Associates specializes in geotechnical engineering — the study and behavior of soil and rocks and how that applies to things such as building foundations, pavement subsurface, slope stability and other related items.

Bergin, who said the full report was delivered to the township in a thick binder, said the engineering firm, which was hired by Ocean County, had several findings:

The Parkway road surface is about 5 feet higher than the western side of Greenbriar 1. That drop-off means that any backup of water at the culverts during severe rainfall would cause flooding, and that flooding would have happened both before and after the changes to Interchange 91.

In historic rainfall events, part of the runoff to the north culvert of the Parkway "will overflow the banks of the upstream channel and flow to the GSP south culvert." In the August 2018 storm, the overflow was estimated to be 352 cubic feet per second, almost doubling the flow to the south culvert. "The GSP South Culvert is a smaller pipe with less capacity than the GSP North Culvert," the report summary said.

There have been improvements to both culverts since the storm, but "based on the extended duration of flooding condition, there appears to have been some blockage of the flow at the culverts."

The firm concludes the interchange improvements and the improvements to Burrsville Road had no effect on the flooding.

Bergin said the firm looked at photos of the flooding taken by Brick Township police drones, examined the culverts in question in person and examined the engineering drawings as well to reach their conclusions.

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