Digest>Archives> Jul/Aug 2022

From the Commodore

“Building the Marginal Depot Wharf”

By Debra Baldwin


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Frederick P. Dillon

Editor’s note: During the spring of 1923 through the winter of 1924, Frederick P. Dillon was serving as the 9th District Supervisor, stationed in Puerto Rico accompanied by his wife Miriam, son Scott, and daughter Kathleen, all of whom are mentioned in this excerpt.

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Dated May 21, 1923, the sheet piles are cut off ...

The arrival of the tender Columbine from Key West (the captain sometimes referred to her as the Concubine), emphasized an engineering problem for me. The Depot wharf was thoroughly rotten. Piles and decking and had to be completely rebuilt now. I had seen the local contractor, Felix Benitez Rexache build the Malicone Marginal Bulk­head Wharf for the city, which suggested the same type for the Depot.

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By June 23, 1923, the longitudinal concrete beam ...

Our draftsman, Rafael Garcia, laid out such a strip of a deck or wharf some 700 feet long by about 15 feet wide, enclosing the evil-smelling muddy beach facing the harbor. The plan involved driving and jetting tongued-and-grooved, reinforced concrete piling, capped by a heavy concrete longitudinal beam, which tied the heads of the sheet piles together, which in turn, acted as the inner support of a 15-foot-wide, heavy concrete deck, supported by beams and two rows of concrete piles.

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When enlarged, this September 4, 1923 photo shows ...

The whole marginal wharf was held back to resist the fill by creosoted piles and batter piles with tie-back rods, which were to be buried in the fill. This would give the tender a 700-foot face of the wharf for loading and unloading. To replace the old dock, a cost of $60,000 was estimated. So, I, who was always putting my foot in it and pulling it out painfully afterward, submitted this price for the new marginal wharf, knowing how “tight” the Bureau was for any projects, no matter how urgent.

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This photo, taken on January 30, 1924, shows the ...

Contactor Rexache told me afterwards that he could not build the wharf by contract for less than $200,000, so I was bound to use our own forces for the construction. The Bureau promptly allotted the funds according to my original estimate. I leaned heavily on our own fine construction staff: Tom Sampson, whom I had recommended for promotion as my assistant; Rafael Garcia, designing draftsman; the construction force under Salgado; and last, but not least, the 26-man crew of the tender and Big Martin, the bos’n, who knew how to handle great weights, if any man did. My ingenuity was taxed to the limit.

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Commodore Dillion’s personal aerial photo of the ...

Needless to say, the labor furnished by the tender was not charged to the project. The great concrete expanse of the Depot offered an ideal space for casting piles reasonably close to the tackle of the tender. On scanning the War surplus stocks, I discovered a fine heavy steam hammer at Panama, soon shipped to San Juan. A barge, hoisting engine and boiler were rented locally.

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The original caption for this January 30, 1924 ...

Salgado constructed special leads for vertical and batter piles and assembled the gear on the barge. The tender’s crew, under Big Martin’s direction, brought the piles to Salgado’s piledriving crew on the barge and all, including myself, pitched in with enthusiasm to construct the marginal wharf.

A considerable number of barracuda and other tropical fish were trapped in the pool behind the wharf. Groups of Scott’s Puerto Rican pals, with fishing lines and spears, pursued the finny tribe, but Urrutia, the Depot guard, had to keep a sharp lookout to see that none of the boys were drowned. The question soon presented itself: How was the fill to be made behind the wharf to the Depot grade?

As luck would have it, the United States Engineer suction dredge, a monster with a 20-inch diameter discharge pipe, was clearing San Juan Harbor of shoals, pumping them off to one side of the channel. I had friends in the district engineer’s office in the old Naval station adjoining the Lighthouse Depot, so I discussed our filling problem with them. Captain Edholm of the dredge came and looked over the situation and offered to pump the Depot pool full with material from the harbor as a favor to me at no cost. He had to get rid of the material somewhere.

In one day’s time, the pool was full and overflowing out of the spillway provided at the end toward the dwelling. I noted with horror that the soft mud had put a terrific strain on the sheet piling of the whole wharf and pushed it out toward the harbor a foot or more. I called in contractor Rexache, who had a world of experience in such matters.

“Don’t worry a bit about it,” he said. “You should have seen the Malicone Wharf sheet piling when they filled behind it. It bulged out twice as far as yours.” I had visions of the whole sheet pile retaining wall collapsing and the project a failure.

Captain Edholm, seeing the predicament of a fill of soft mud that would not solidify in years, said, “We’ll fix that. I know where there is a bank of coral sand that needs removal.” The very next day, the dredge cutter head was working in that bank. The fill of coral sand and chunks of coral rock and seashells poured in at one end pushing the mud over the spillway making a solid fill that could be walked on immediately except at the spillway end where there were deceiving pockets of mud covered with sand.

Scott’s friends, and even I, in spotless white, could not restrain our curiosity in testing out the bearing power of the fill there. Result: I broke through up to my middle. The children’s pet, scrawny cat “Koos,” while chasing lizards in this area, went through one night and dragged herself out of this mess and sought comfort by leaping on top of Kathleen’s bed net. “Oh, Mother, Mother,” Kathleen cried, wakened out of a sound sleep. “Come quickly. Koos is leaking mud all over my bed.” Miriam, in the middle of the night had to give Koos a bath in warm water, with me holding the rebellious cat, for cats do not like to be bathed, but Koos, no matter how hard she tried, could not lick that mud off. The filling of the Depot pool was long remembered.

This excerpt is taken from “Superintendent of Lighthouses – 9th District: 1920 to 1927” in The Making of a Lighthouse Engineer, the unpublished memoirs of Commodore Frederick P. Dillon.

This story appeared in the Jul/Aug 2022 edition of Lighthouse Digest Magazine. The print edition contains more stories than our internet edition, and each story generally contains more photographs - often many more - in the print edition. For subscription information about the print edition, click here.

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