Plan for the catastrophic deluge on Long Island

We know what devastation looks like on Long Island. We all remember vividly the damage caused six years ago by superstorm Sandy.

Since then, steps have been taken — from hardening some infrastructure to raising some homes — in preparation for the next big one.

But what if the next big one is not another Sandy? What if the next big one is like Hurricane Florence, which dumped 36 inches of rain on parts of North Carolina? Or Harvey, which drowned Texas with up to 61 inches?

Sandy was a wind event. It was huge, but it only brought a couple inches of rain. Two years later, we got serious rain when a freakish August storm drenched parts of the Island with 13 inches in a few hours. That was enough to fill basements, overwhelm drainage systems and strand hundreds of cars.

Imagine three times that much rain across Long Island. Some of Sandy’s storm surge, which was 8 to 10 feet or more on parts of the South Shore, came in through storm drains; any Florence-type rain would have nowhere to go.

Such an incident now would be bad. And it’s not going to get any better. Sea levels are rising. The midrange projection by state officials is 16 inches in 2050; the high end by 2100 is 6 feet. Surges will worsen, year by year.

Add other effects of climate change that help create these monster monsoons — warmer oceans fuel storms, warmer air holds more moisture, and slower air currents stall systems, with huge amounts of rain dumped in one place.

That would be catastrophic for Long Island. And if you’re saying to yourself that it won’t happen here, lots of other Americans said that, too — until it did.

Consider what could happen here in a storm with 30 to 40 inches of rain:

• Sewage treatment plants on our coasts could shut down. Bay Park in Nassau County failed during Sandy, dumping 100 million gallons of raw sewage into Reynolds Channel. The plant has a protective wall now, but the big Bergen Point plant in West Babylon doesn’t, and it came within a hair’s breadth of being flooded by Sandy. Designed at the time to treat 30 million gallons a day and required to handle a peak of 60 million, it was inundated with 120 million gallons during Sandy.
• Cesspools would overflow, and Suffolk County has 360,000 homes not connected to sewers. For cesspools close to the surface, raw sewage would rise up into the surface water.
• Beaches and shellfishing beds that are commonly closed after moderate rains due to bacterial contamination from stormwater runoff would be shut for days or weeks.
• Farming would be devastated. At this time of year, such a storm would wipe out the fall harvest, and soils would be contaminated by floodwaters that also would carry pesticides and fertilizers from farms into local creeks and bays.
• Rivers would overflow, threatening development along them; trees would be uprooted, damaging houses and power lines; and our folly of building too close to the water would be exposed again. The Island’s interior, immune to storm surge, would confront the rain with storm drains designed to handle only a 5-inch storm in 24 hours — in areas that even have storm drains.

What follows could be worse, as the horror of environmental damage comes into focus. That’s what happened after Harvey with compromised chemical plants and after Florence with breached hog waste lagoons and coal ash pits.

Floodwaters could disturb contaminants from more than 180 federal and state Superfund sites on Long Island. Flooded basements, garages and businesses would mix heating oil, household chemicals and paint into the water.

Waterlogged homes would produce a solid-waste nightmare. Contents would have to be thrown out. Nearly 250,000 cubic yards of Sandy debris from Long Beach alone were piled at Nickerson Beach Park in Lido Beach. Multiply that across Long Island, and consider that all of that would have to be taken off the Island because we can’t landfill it here. The logistics are boggling.

It’s a lot to think about. But we have to get started, to make sure we’re as ready as possible. We can’t afford to be preparing to fight the last battle, when the next one could be something very different.