DEP Says Chlorine Deliveries to Island
Will Be Safe; Others Are Not So Sure

Roosevelt Island got its first taste of chlorine, and the reaction was toxic. No one, it seems, enjoys the thought of chemical tankers trundling along Main Street, especially when Main Street happens to be the only street.

Chlorine deliveries will be a common sight on Main Street in the future – probably around 2011 – and the Island’s first taste of it was served up by a hastily assembled, sparsely publicized town meeting on November 16 at the Good Shepherd Community Center, called to order by RIOC. Representatives from the City Department of Environmental Protection (DEP) were there to outline the scenario that has thus far been calculated for the care and feeding of a very important hole in the ground in the northwest quadrant of the Island. That hole is known as Shaft 15B of Water Tunnel 3, the long-awaited system designed to relieve the strain on Tunnels 1 and 2, which have been providing New York with all its fresh (and notoriously delicious) drinking water since 1917 and 1936, respectively.

Once Water Tunnel 3 is operational, sending water from 19 upstate reservoirs down to Central Park, across to Roosevelt Island, into Queens, and then down to Brooklyn, Shaft 15B will require chlorine, and plenty of it. The chlorine will be delivered in the form of sodium hypochlorite, a liquid that at lower concentrations is no different from what you pour in swimming pools to keep the algae from taking over.

But the news that chemical tankers are heading this way over the Roosevelt Island Bridge was hard to swallow for anyone in the audience without an advanced degree in chemical engineering.

Once the trucks reach the foot of the ramp opposite PS/IS 217, they will turn right on Main Street. And no matter how hard the DEP reps tried to explain the nature of the chemical they’ll be transporting and the numerous safety precautions they’ve put in place, the follow-up Q&A period was filled with questions and concerns about chemical trucks barreling into schools and senior centers or being blown up by terrorists.

"It’s basically liquid beach, as in Clorox," explained Kevin Clarke, executive project manager, division of facilities improvement, from the DEP’s Bureau of Environmental Engineering. "It’s a safer alternative to chlorine gas," the substance more commonly used as a disinfectant in the past, but which had the nasty habit of exploding into killer gas clouds whenever there was the slightest accident.

Sodium hypochlorite, the substance that will be in the trucks coming to Main Street, doesn’t explode, doesn’t release a chlorine-gas cloud, is not flammable, and is considered significantly less hazardous by EPA standards – even though you still wouldn’t want to inhale it or touch it if it spilled. It disperses quickly in open air, but initial close contact with it can sting the eyes, skin, and lungs.

Shaft 15B will serve as a booster station at the deepest point of Water Tunnel 3, 800 feet beneath the East River. This is where chlorine will be added as a disinfectant to keep the city’s drinking water safe from bacteria and contaminents; until now, all that disinfection has been occurring so far up the line that some reservoirs have been "overdosed" with chlorine to ensure the chemical survives the full trip to New York City’s taps.

"We need a chlorine residual in the water-supply system," explained Clarke. "In order to do that, we need higher doses of chlorine at Kensico Reservoir [in Westchester], and it sometimes exceeds the threshold to the point where chlorine is detectable in the water. Residents in the upper reaches are affected by this overdosing."

Shaft 15B will alleviate that problem, as well as constituting an essential part of a system that will allow the older tunnels to be closed for inspection for the first time since they were built. Water Tunnel 3 "provides the spare tire," as George Fox, former chairman and president of Grow Tunneling, once put it.

Trucks will make the chlorine deliveries weekly, if not more frequently, each one holding from 2,000-5,000 gallons of concentrated sodium hypochlorite. Clarke said the deliveries would be made during business hours, but retracted that after several Islanders pointed out that congestion at the pivotal intersection between the bridge and Main Street would severely compromise traffic and quality of life. "All this is very preliminary," he reminded the audience.

Why will Shaft 15B be so thirsty? Clarke explained that chlorine loses potency quickly. Although there are two 3,800-gallon storage tanks in an underground bunker alongside the shaft, the chemical degrades too quickly to keep for long. The chlorine precipitates out as a salt, and the gas that’s emitted is oxygen.

Michael Shinozaki, a resident member of the RIOC Board with an engineering background, challenged Clarke over several significant issues, including why the DEP wasn’t looking into delivering the cargo by barge instead of truck, and over the wisdom of beefing up security around the shaft itself while ignoring "the single choke point" where "a truck with hazardous material is coming down the ramp" toward the school, with the Senior Center nearby.

Clarke said the idea of barging the chlorine was discarded early on as not cost-effective due to the relatively small amount of each delivery (he said no barges were available for such small loads anyway), and discussion of the "choke point" on Main Street quickly went nowhere, loudly.

Helene Rutledge, a chemical engineer who, early in her career, worked exclusively with sodium hypochlorite while developing a commercial mildew remover, spoke with The WIRE about the hazards of the chemical, and said the audience’s reaction was typical of what engineers refer to as "chemophobia" – an excessive distrust, by the general public, of all things chemical.

"You certainly have to be careful around it," cautioned Rutledge. "This is a strong concentration of chlorine, stronger than household detergent. But if you mix bleach with ammonia in your house while cleaning, you’re breathing chlorine gas, and that’s a much greater danger and more common because it’s in your home in a confined space."

As for the possibility of exposure to the substance, Rutledge said she "once knew a guy who, in the days before OSHA standards, dipped his hand into vats of sodium hypochlorite so many times over the years his fingerprints were gone. If you had an overturned truck, if you have a spill that gets into the sewer directly, a large quantity of it might wreak havoc with a waste-treatment facility. But the bigger danger is probably that if it spilled into the river, it would harm the wildlife."