More 14th St. - Canarsie News - Trains Magazine

Last time we checked, nobody has fixed the climate crisis. Rising sea levels and superstorms, like the one that swamped the L tunnel in 2012, remain looming threats to the planet, including our subway system.

So, hardening our system against climate impacts is a big part of modernization—and the L Project. One example we mentioned in last week’s resiliency rundown is the work we did at the N 7th St. Fan Plant on the Brooklyn side of the L tunnel. To explain why this particular fan plant is at more risk than others and what we did about it, we talked to engineer Amen Mukhlis and resiliency manager Steven Loehr.   

L Project Weekly: First, guys, tell us what a fan plant is for.

Amen Mukhlis: Sure, a fan plant is just that. It’s a facility with very powerful fans that ventilate a section of the subway tunnel. It’s not for constant ventilation, but it’s critical for safety. It will clear smoke if there’s a track fire or just hot air to keep our crews cooler. Right now, we have 204 fan plants across the system. That includes one fan plant on each end of all our under-river tunnels. There’s no street grating there, of course, so fans are the only way to vent those tunnels.

Steven Loehr: Let me just add that 32 of our fan plants are in flood zones. The N 7th St. Fan Plant on the Brooklyn side of the L tunnel is one of those. It’s right beside the river. Because it’s for ventilation, it must have large open shafts to push air out. But those openings could also let massive amounts of water in.

LPW: So, this fan plant must be located right at the end of the L tunnel. But that’s next to the river and in a flood zone.

AM: Right, it’s in a SLOSH Cat 2….

LPW: Wait, did you say Slosh Cat… like a drenched kitty? What’s a Slosh Cat?

SL: It’s a National Oceanic and Atmospheric Administration (NOAA) term. It stands for Sea, Lake, and Overland Surges from Hurricanes. SLOSH! Anyway, it’s a computer model for predicting storm surges on land. Like most of our flood-vulnerable facilities, we are protecting that fan plant against a SLOSH Category 2 surge, plus three feet. What we call SLOSH Cat 2 plus 3. Skipping the math, that’s flooding up to 11 feet above ground level. Which is massive flooding! 

LPW: Okay, so how do we protect our fan plant from the big slosh?

AM: The fan plant itself was basically okay. It didn’t make any sense to totally knock down the 1916-structure and rebuild it. So, what we did—and this is new for us—we upgraded the plant and built a protective envelope around it. The envelope is 18-inch-thick, cast-in-place concrete. The piles extend 40 feet underground, down to the bedrock, so flooding can’t flow underneath and push up the structure. We sealed the entrance with heavy, tight-locking marine doors. Literally like you’d have in a submarine.