In an effort to leave no stone unturned in getting the lowest price possible, engineers are being asked to study what might be called a ‘let it flood’ scenario for fighting rising seas and persistent street flooding in Key Biscayne
The newest option, which came at the request of Council Member Brett Moss, would allow for so much street flooding that only emergency vehicles could traverse village streets at the peak times of a deluge. Streets would be filled with as much as 14 inches of water not to exceed 12 hours.
To be clear, the bargain-basement concept wasn’t recommended by Village staff – it’s just another “what-if” to be considered before a January vote on the next step of the Big Dig projects, which have been delayed for months.
Village Manager Steve Williamson has been trying to get the mammoth project back on track, arguing the island is facing an existential threat that will only grow more costly if action isn’t taken.
With Moss’ scenario included, the Council voted 6-0 – Oscar Sardiñas was absent – to authorize AECOM to run the “variant” scenarios after the original set of flood targets resulted in a $310 million price tag. Moss was part of the 7-0 vote that set those targets 20 months ago.
As officials met, the Village was dealing with a large weather system dumping significant rain – and flooding. Officials did not report any major incidents, but the National Weather Service issued flash flood warnings. Fire Chief Eric Lang said there could be as much as 8 inches of rain, but the official forecast called for half that amount.
Moss has talked about how keeping the streets dry in a major storm didn’t make economic sense, saying up north during big snow storms people stay home and ride it out.
A storm of that magnitude would be a rare occurrence with 99% of rain storms historically on Key Biscayne dropping 2.5 inches or less of precipitation, according to Chief Resilience Officer Roland Samimy. But rainfall is expected to increase in the future, and sea level rise will magnify the effects of even smaller storms, scientists say.
Moss also pressed the Council to come to a consensus on what is an acceptable cost for the project, throwing out $150 million as an example.
“So if they’re going back and doing all this and they go from $300 million to $250 million, we’re not even getting close,” he said.
Council Member Ed London went even further than Moss with a proposal. “Ask Chief Lang to look at increasing the size of the tires on the trucks,” he said. “Which would raise the 14 inches, probably to 16 inches.”
The other dozen “variants” for the modeling were discussed by Council at an Oct. 26 workshop. The tweaks include increasing the outfall velocity into Biscayne Bay, optimizing pipe sizes, modifying the amount of runoff and an incremental approach to factoring sea level rise.
AECOM will return next month with plans with varying levels of service and costs based on the new modeling.
Moss said he added the worst-case scenario because he fears that AECOM will still come up with a project that is too expensive.
Samimy said he felt confident when AECOM comes back with the results of the new modeling runs, “you might be surprised at how much the price will change.”
Council Member Allison McCormick – who was chosen as the new vice mayor at Tuesday’s meeting – said she wanted to be able to tell the average property owner on Key Biscayne how much the new system would cost them out of pocket.
Village Manager Steve Williamson said the project will be paid for through four ways – much of it through borrowing that will spread the cost out over 15 years or more and grants that will reduce the cost to taxpayers.
The Village has already been approved for low-interest state revolving loans for some of the storm water work. In addition, it will issue “GO” bonds, approved by voters in 2020, in stages matching the phases of the project. And, said Williamson, the general capital improvement fund will be tapped now to pay some costs.
But details of the finance models being developed by Chief Financial Officer Benjamin Nussbaum are still in progress and have not been made public.
Still, Council Member Fernando Vazquez worried that costs could still balloon once shovels hit the ground.
“Then we’re going to be at the contractor’s mercy,” he said. “Once they capture the site, then forget about the price that we originally opined on. We have a real cost and a real contract.” kj