AVALON – The north end of Avalon is best described as an “elongated bowl” from 22nd to Eighth streets in the words of Borough Engineer Thomas Thornton.
Water built up from major rain events cannot be emptied fast enough by current drainage systems to prevent the risk of substantial property damage.
Thornton and the engineering firm of Mott MacDonald presented options for improving the drainage systems in that portion of the borough at a governing body’s Aug. 22 meeting.
The problem is simply stated: solutions are expensive.
The north end is vulnerable because there is no place for the water to go without engineered intervention. The dunes to the east block access to the ocean and the water that is pumped to the bay, on the west, must go through pipes that penetrate the bulkheads.
Mott MacDonald presented three options for pump reconstruction and major alterations to drainage pipes.
The only way to deal with the potential damage of a major rain event, Thornton said, is to move the water out quicker by using more powerful pumps and larger pipes.
The construction costs can range from $8.6 to $10.7 million.
The options were organized around the level of risk the borough is seeking to address.
Labeled as 25-, 50- or 100-year rain events, the design criteria are based on the size of the rain event the system is supposed to protect against.
Since protection comes with a big price tag, Councilman John McCorristin wanted to be sure the public understood what the price did not include.
“This is not what some people think of when they hear the term a 50-year storm event,” McCorristin said.
“This is about rain events only,” he added in an effort to make clear that the investment being considered is not aimed at adding protection from coastal storm surges.
The borough council then directed Thornton to design to the criteria for a 50-year rain event. The resulting system would come at a currently estimated cost of $9.5 million.
In order to help spread the financing over a time period; Thornton presented a possible approach that would phase construction over a three-year period.
The proposal was to deal with the 11th Street pump station in year one. Follow that with upgrades to the 22nd Street pump station in year two.
Year three would see the replacement of pipes in the drainage system. According to Thornton, using 2019 for formal design would allow construction to begin as early as 2020.
While council reached an apparent consensus on the 50-year rain event criteria, no decisions were made on the construction phasing. Council wished to see more detailed design information before a construction decision.
Three times in the past several years, rain events have been severe enough to cause significant damage to property in that area of the borough, the latest being in 2016.
To contact Vince Conti, email vconti@cmcherald.com.
