NEWTOWNCREEK WASTEWATER TREATMENTFACILITYSpace Oddity

By day, the egg shaped digester towers of the Newtown CreekWastewater Treatment Facilitybarely show up in the glint ofGreenpoint’s industrialized waterfront. But by night, their stainless steel cladding bathed in a diaphanous blue glow, the mono-lithic egg towers and their steeland glass aerial walkways standout fabulously, seemingly poisedfor an interstellar evacuation of thecity’s five boroughs rather than thevital daily mission of treating 310million gallons of its wastewater.

Fed by 180 miles of sewers andserving over 1 million residents in adrainage area of more than 15,000acres, the treatment towers atNewtown Creek couldn’t afford to go offline at anytime during acarefully planned upgrade to this system of anaerobic digestion. Sowhile interstellar evacuation mighthave been easier, steel’s malleabilityand structural integrity were inherent advantages in achievingthe unearthly look of the towersand their elevated walkways, mostimportantly allowing the speed andease of erection that was essentialto the success of the project.

Sci-fi aesthetics weren’t alwaysincluded in the Department of Environmental Protection’s $2.2billion expansion and upgrade ofthe Newtown Treatment facility.

Richard Olcott and Greg Clawsonof the highly acclaimed PolshekPartnership Architects, the project’sdesigners, recall the early days of their firm’s role as overseeing architects for the continuous 16-year renovation project. Theproject is a collaboration betweenPolshek Partnership and a triven-ture of engineering firms, GreenleyHansen, Hazen and Sawyer, andMalcom Pirnie.

“Back when we were designingthis, there was a movement fromthe local folks around the area, the engineers and the DEP, tryingto push us to make the plant out of brown brick,” explains projectarchitect Clawson. “Obviously, theywere trying to hide it from view,and it just wasn’t going to happen.”

“It’s hard to hide a 110ft tallbuilding,” concedes Olcott, designpartner for the project. “So, ratherthan hiding it we thought weshould do the opposite: We shouldreally show the thing off and makesomething everyone would look atand go—‘Wow! What’s that?’”

Engineering marvels in and ofthemselves, the German-designeddouble curvature of the egg shapeddigesters (ESDs) encourages animproved mixture of sludge, the organic material removed fromsewage for anaerobic treatment,by concentrating grit at the bottom

Right Rather than try to hide the 110-foot-tall digester eggs, Polshek decided tocelebrate them, cladding the exotic forms in stainless steel and commissioning a startling nighttime lighting scheme from L’Observatoire International.

14

16 Metals in Construction Fall 2008

Pre

viou

s pa

ge: ©

Wal

ter

Duf

resn

e; th

is a

nd fa

cing

pag

e: ©

Ais

linn

Wei

dele

/Pol

shek

Par

tner

ship

Arc

hite

cts

19Newtown Creek Wastewater Treatment Facility

© W

alte

r D

ufre

sne

18 Metals in Construction Fall 2008

Previous The steel trusses of the catwalks were delivered on site, hoisted into place by three tower cranes,and pinned in place.Above The stainless steel cladding offers exceptional corrosion resistance,an important quality in a facility thatprocesses 1.8 million gallons of sludgeper day.

NEWTOWN CREEK WASTEWATER TREATMENT FACILITY

Location: 320 Greenpoint Avenue, Brooklyn, NYOwner: NYC Department of Environmental Protection, New York, NYArchitect: Polshek Partnership Architects, New York, NYStructural and Mechanical Engineers: Greeley Hansen, New York, NY;

Hazen and Sawyer, New York, NY; Malcolm Pirnie; New York, NYJoint Contractors: AJ Pegno, Oyster Bay, NY; Tully Construction, Flushing, NY;

Skanska USA Civil, Whitestone, NY; Slattery Skanska, New York, NY; Gottlieb Skanska, Valley Stream, NY and Underpinning & Foundation Skanska, Maspeth, NY; Picone/McCullagh JV, Brooklyn, NY; and Perini Corporation, Framingham, MA

Structural Steel Erector: Budco Enterprises, Hauppauge, NYStainless Steel Cladding Fabricator: Overly Manufacturing Company, Greensburg, PA

of the tank, virtually eliminatingdead zones and scum buildup—elements which force conventionaltanks off-line for costly periodiccleaning. Though early ESD facilitieswere constructed of poured-in-place concrete, the difficulty andcost of forming the complex shapesnecessary for such construction finalized the DEP’s decision to shift the primary material to steelthroughout.

At the Newtown Creek facility,Polshek crowned and linked theESDs with steel and glass aerialwalkways and turrets that glow likelanterns at night. Steel’s speed ofconstruction, flexibility, and lighterload weight were pivotal factors in the construction phase, as the congested conditions of the 24-hour site required a constantcoordination of logistics betweenarchitects, engineers, contractors,and facility technicians. With steel,sections of the aerial walkwayscould be pre-fabricated and assembled on location with minimalscaffolding and workmanship, allowing connections to be weldedand bolted in an efficient and convenient way.

The aerial walkways and turretsare made up of a variety of steelmembers, including structuraltubes of ASTM A500 Grade Bsteel, structural pipe of ASTM A53Grade B steel, and other shapesand plates of ASTM A36 U.O.N.steel. The turrets are framed withW10x15, W10x33, and W24x68wide flange members, while thewalkways spanning the distancebetween them are composed of steel trusses made up of W8x15diagonal braces, W10x22 crossbeams, and W24x104 main beams.Each truss weighs approximately30 tons.

Originally intended as a pedes-trian concourse around the groundfloor of the plant, architects choseto elevate the walkway due securityconcerns and the impracticality offoot traffic between the wide-basesof the ESD’s. But life at the top is not without its challenges. To equalize air pressure and wind loading, the aerial walkways’ enclosure is composed of a seriesof independent, non-connectingcomponents; a slight separationbetween the stunning metal roofand the glass paneled siding creates a kind of vented claddingsystem that allows sufficient air tomove in and out of the enclosureunder applied air pressure.

“These things we knew fromthe beginning were going to bestructural steel elements; there are movement joints in the aerialwalkway system that keeps themfrom cracking at the ends,” saysPolshek architect Greg Clawson.“They’re bridges, basically.” Eachwalkway section has a pinned connection at one end and a slidingconnection at the other end. Thesliding connection sits on a ¾-inchbearing plate with a ¼-inch Teflonbearing pad.

The walkways were delivered to the site in mainly pre fabricated,shop welded sections. In some instances, other sections wereshipped loose for field welding, thenfastened in place with structuralgrade bolts. The main structuralwork of the aerial walkways wasset in place one month after thecompletion of the digester tanks,which took 102 weeks to complete,at an average of about threemonths per egg.

With diameters of 84 feet andheights of 90 feet, each of the eightegg digesters is clad in S31600stainless steel, with a low-reflectivityproprietary finish. Similarly, the aerial walkways are clad in anepoxy finish that offers exceptionalresistance to atmospheric corrosionand oxidation—key strengths for afacility meant to process 1.8 milliongallons of sludge per day.

“All the materials throughout areselected to be incredibly durablebecause it’s a very corrosive envi-ronment.” explains Richard Olcott.“Not only because of the salt airand the river air, but because thematerials need to last for hundredsof years. Like any other of the projects that were constructed a hundred years ago, you have tobuild these things to last.”

Thanks to steel’s ability to integrate form and function, Newtown Creek’s egg digestertowers and their aerial walkwaystranscend and demystify what otherwise might have been concealed, contributing yet anotherunparalleled sight to New York’sskyline. “It’s a twenty-four hour facility; we don’t want it to appearlike a black hole at night,” says Olcott. “You can see this thing fromthe Kosciuszko Bridge, apparently.”“You can see it from the L.I.E.,”continues Clawson. “When youcome out of the tunnel you just lookto your right and it’s all right there,in front of you.” Beam me up Scotty!M