In the mid-1800’s, the New York Harbor Commis-sion requested Federal assistance in opening upNew York’s Hell Gate. The reportrequesting Federal aid for remov-ing obstructions to navigationsaid, “For several years there hasbeen a gradual but constant in-crease in the tonnage of vessels en-gaged in foreign commerce… andtheir draft is still increasing. It isimprudent to send a ship of thelargest class to sea.”

Although that report asking forFederal support to open up a NewYork Harbor channel waswritten nearly 150 years ago, theneed is still present today. TheU.S. Army Corps of Engineerssince its earliest days continues itsmission of maintaining the depths of federalnavigation channels in one of the nation’sbusiest ports.

Recently, the Corps finished work on anotherdifficult navigation project in New York Harbor—

dredging and underwater demolition to deepenNewark Bay and Kill van Kull to accommodate

deeper draft ocean vessels. TheCorps’ accomplishment brings tomind a famous earlier project,Hell Gate on the East River, aproject that also called for under-water demolition work on even agrander scale.

Deepening today’s channels from35 ft. to 40 ft. also required inno-vative demolition work but undermuch better controls, to be surethan those of a century ago.

The story of Hell Gate marks thebeginning of the civil worksmission performed by the U.S.Army Corps of Engineers. It was

a massive challenge for the Corps fraught with“endless obstructions.”

Hell Gate is located on the East River atthe confluence of the Harlem River. FromManhattan, Hell Gate runs from 90th to 100th

The

Conquest ofHell Gate

The Great Blast of Flood Rock in 1885 “The greatest quantity of explosives ever attempted in a single opera-tion.” Fifty-thousand people crowded both shores of the East River to witness the great underwater explosionthat leveled the rocky reef which made navigating Hell Gate very hazardous.

Streets. It connects Long Island Sound with NewYork Harbor.

Captains of vessels traversing this perilous one-mile passage of the East River described it in logsdating back to the early 1700’s, as a key gatewayto the Atlantic, marked with a giant whirlpool,punctuated with rocks,reefs, and islands. To a seacaptain worth his salt, itmust have appeared asthe gate to Hell.

The reason sea captainsviewed it as hellishwas the fact that the EastRiver is actually a tidalstream whose tides con-flict with waters inLong Island Sound

As Claude Rust in an ar-ticle for Military Engi-neer (1971) wrote, “Whenthe tide rises on theeastern seaboard it setsinto New York Harborand, farther to the north-east, into Long IslandSound. At New York Bayit splits at the tip of Man-hattan, one current push-ing up the Hudson andthrough the Harlem River,the other entering theEast River. Here, with thehorizontal movement im-peded by the opposite flowof the Harlem River andthe narrowness of thechannel up to the Sound,the huge basin of HellGate begins to fill.

The waters, like wild beasts, circle theirconfines, impatient for the chance to escape.The downcoming flow of the Harlem River is thenstopped by the strength of the escaping currentsand sent back up through Little Hell Gate andthe Bronx Kills, and the channels to the west, likea sluiceway, is filled with swift seething waterracing up to the Bronx shore.

This flow continues for hours, building up to ahigh tide along the East River shore. Then at atime when other waters would settle into slack,the downcoming tide, which has been delayed fourhours by the distance and the drag of the Long

Island Basin, begins its relentless drive—and thestruggle for mastery is on. Four hours after en-tering the sound this tide has changed the flow ofthe river which is now down the narrow ‘sluice-way’ from the Bronx and down Little Hell GateChannel into Hell Gate Basin, counterclockwisearound Millrock and as far down the river as the

upcoming tide will allow.

To this confusion of ebbsand flows, currents andeddies, add the rocks,reefs, and the freakishwhims of the winds. Atebb tide the process wasreversed, but no less con-fusing.”

Other historians of theperiod reported thatabout one in 50 ships try-ing to run the gauntlet ofHell Gate was eitherdamaged or sunk in the1850’s. In an averageyear, 1,000 ships ranaground in Hell Gate.

If Hell Gate could bemade relatively safe fornavigation, several oceanmiles could be saved inreaching the Atlantic. Nolonger would ships sitidle burning coal andwasting money waitingfor the tide. A French en-gineer, Monsieur Ben-jamin Maillefert, washired in 1850 by Mr. E.Meriam, “a public-spir-ited citizen of New York,”to remove some of thelarger rocks in the Hell

Gate area. Meriam sought donations from NewYork merchants to remove some of the rock “pri-marily because Congress was not in a spendingmood.” Maillefert, who had worked with the Brit-ish Royal Engineers agreed to remove Pot Rockand Ways Reef for $15,000. The method of rockremoval was unique for the time calling for “theblasting of rocks under water without drilling.”Maillefert proposed to lower a canister of gunpow-der to the rock by rope via a lengthy pole, andthen set off the explosive from a safe distance.

The first blast knocked four feet off the top of PotRock and the project was on. The bombardment

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Strong cross currents combined with shallow rockywaters earned Hell Gate it’s name and reputationfor being a navigator’s nightmare.

continued for several months. A barrage of 284charges set off on Pot Rock gave a clearance of18 feet, and 240 on Frying Pan and Ways Reeflowered them 9 1/2 and 13 feet, respectively, from the surface.”

According to Rust’s account: “The relentless blast-ing of Hell Gate went on till March 1852, whenthe law of averages caught up with Maillefert.After placing a 125-pound charge of powder atopa rock, he took what he thought were the leadwires to the submerged mine and paid out theline till he and the supply boat were a safe dis-tance from the explosion site. Upon touching thewires to the battery terminals in his boat, he blewthe other boat clear out of the water and wasthrown 50 feet in the air himself. Of the five menin the operation, three were killed and Maillefertand his assistant were disabled.”

Maillefert’s efforts dismantled the whirlpoolalmost entirely with the added benefit of easingtide flows. He claimed that if his operations wereto continue that Hell Gate could be the safestentrance to the Harbor.

“These few words from a man of action did moreto move Congress than all the pleas of the past. Itsuddenly appropriated $20,000 for carrying on thework under Lt. Bartlett of the Army Corps of En-gineers. But this fund was soon exhausted, alongwith the Frenchman’s verve, and the work onceagain came to a halt,” writes Rust.

Interest in clearing obstructions from Hell Gatelanguished until after Civil War hostilities. A citysurveyor and civil engineer suggested filling inHell Gate thereby making room for an anticipatedgrowing population across the East River fromManhattan. However, Congress thought other-wise, saying it was more prudent in terms of coststo demolish the rocks at Hell Gate.

In January 1867, Maj. Gen. Andrew Humphreys,Chief of Engineers, assigned Lt. Col. John New-ton from New York District to study the best planof attack for removal of Hallet’s Point reef andthe subsequent removal of Pot Rock, Frying Pan,Heel Tap, Shelldrake Rock, Ways Reef and othersmaller rocks and reefs.

At 11:13:50.2 AM, on October 10, 1885, with all charges in place, the cavern at Flood Rock flooded with water—12 year old Miss Mary Newton pressed the key that set the charge and snapped the shutter of the camera thattook this picture.

Newton awarded the contract for removal ofHallet’s Point to Sidney Shelbourne who hadinvented a floating rig designed to make under-water demolition easy. Shortly into the operation,his rig was “run over by a tug, a brig, and a canalboat, destroying the equipment completely. Thefinal blow fell on Shelbourne when his twice-ex-tended contract expired three days after his drillrig was wrecked.”

Enter the Frenchman, Mr. Maillefert, who wonthe contract to remove Pot Rock, Way’s Reef andShelldrake Rock at $44.28 per cubic yard. His ef-fort failed also.

Newton continued the effort with an invention ofhis own. He described it as, “A drilling machinewith nine drills, or as many as may be convenientto place within it, 30 feet in diameter and, beingfurnished with self adjusting legs, is let downthrough the well hole to the rock. The drills areworked by steam or hand power and the holescharged with nitroglycerine or some powerful com-pound, and exploded.”

Newton, in a 1871 report, related, “during themonths of May and June, the drilling-boat encoun-tered six collisions several of which did much dam-age by forcing the scow upon the dome… The de-lays and loss of time due to these collisions havebeen great.”

The lesson learned: Any rock removal operationat Hell Gate would not be successful if conductedon top of the water.

Now a general, Newton, was given the taskby Congress to continue his efforts at Hallet’sPoint Reef. He decided to employ “subaqueoustunneling.”

One historian’s account described how itworked this way: “The reef was to be underminedwith a series of passageways, charged with ex-plosives, and blown up. The initial step in thisengineering project was the construction of a cof-ferdam at the water’s edge to prevent flooding ofthe works at high tide. Inside this U-shaped wall,a deep pit was to be dug below the riverbed leveland from this a series of tunnels were to radiateinto the bedrock of Hallets Point Reef.

“For seven years the workmen labored, excavat-ing the pit, then inching their way into the solidreef. Tons of rock were blasted from the reef, shov-eled into mule carts, and hauled to the end of thetunnels to be hoisted to the surface. Finally therewere ten headings fanning outward under the reef

connected by a number of gallery arcs from oneend of the fan to the other.

The walls and ceilings of the tunnels were packedwith 7,000 holes ready to receive the explosivecharges. Of this number it was estimated thatcharging 4,000 would suffice to demolish thereef… A total of 30,000 pounds of explosives hadbeen packed into the mines and the job ofcharging was completed.”

Finally, on September 24, 1876 at 2:30 P.M.., themines were fired. According to Newton, “The ex-plosion was distinguished by the absence of hurt-ful shocks in the atmosphere, in the water, or un-derground. The elevation of spray, vapor and gas-ses projected upward, reached to the height of 123feet, measured at the center and highest point.The explosive effort in the air was not perceptible,the glasses in buildings close to the dam and ofone in particular along the shoreline of theshaft itself, not having in a single instancebeen broken.

“The new facts obtained by this experience, are...

1st. That an unlimited amount of explosives dis-tributed in blast holes in moderate charges, pro-portioned to the work to be done, thoroughly con-fined in the rock and tamped with water, may befired without damage to surrounding objects.

“2nd. That an unlimited number of mines may besimultaneously fired by passing electric currentsthrough the platinum wire bridges of detonators.”

After the successful blasting, the Atlantic Dredg-ing Co. worked until 1882 to remove the 90,588gross tons of broken rock at Hallet’s Point thatdeepened the channel to 26 feet.

Newton’s next target was Flood Rock.

According to Rust, “Of the Flood Rock area, only230 square feet showed above the water. A seawall was built around this area and, inside thisenclosure, a large lift tower was built over themain shaft site and drilling was started… A 70foot shaft was sunk, headings branched out atvarious levels and, in the other, a stairway led tothese tunnels. The material excavated was hauledout to the lift by mules and men, raised to thesurface and dumped over the sea wall to forman island for operations.

“For nine years this labor went on: 23 headingswere dug running north and south and 46 galler-ies at right angles to them spaced 25 feet apart…

The reef was honeycombed with four miles of tun-nels… 15,000 holes were drilled in theceilings for the explosive charges.”

Meanwhile, at Mill Rock, an island northwest andnearby, workmen were busy preparing a power-ful explosive mixture they dubbed “Rack-A-Rock.”Some 280,000 pounds of the mixture plus 5,000pounds of dynamite were required for the demoli-tion job.

“Of the 50,000 charges, only 3,000 were connectedto wires, others would go off sympathetically,”reports Rust. Finally, on Oct. 10, 1885, Miss MaryNewton, daughter of General Newton, as she didat Hallet’s Point, pressed the key that simulta-neously set off the charge.

The event was viewed by 50,000 spectatorsand 100 cameras.

Rust gives this account: “With a muffled rumblefrom the depths of Hell Gate, nine acres of the

river surface was lifted into the air, a tremendousmass of rock and foam 150 feet high. A sickeningjar was felt on land, and seconds later waveslapped the shores. The greatest single explosionever produced by man was over.”

Engineering News and American ContractJournal, a trade publication of the period, re-ported, “Although the volume of explosives usedhere exceeded six-fold the greatest charge everpreviously fired in the world, the work of the en-gineers was so well done and the precautionarymeasures of Gen. Newton so well taken, that noaccident or delay of any kind occurred.”

With the elimination of Flood Rock at Hell Gatevessels were able to navigate this passage easily.Shipping trade increased to some $4 million worthof cargo a day, justifying the millions of dollarsfor the unsnagging operation. A shot of new lifewas infused into the Port of New York, which wasonce again able to assert itself as the undisputedleading port in the nation at that time.