Washington Aqueduct Tunnels, Part II

By Elliot Carter | July 28, 2018


Congress waited nearly two decades before again taking on the District’s perennial “water problem.” Although Montgomery Meigs’ Aqueduct tunnels performed as promised, directing an inexhaustible stream of Potomac River water into the growing city, low water pressure and questionable purity began to erode its public image. These issues combined into a regular drum beat of newspaper editorials and constituent complaints demanding improvements. “The cry comes almost incessantly from people living on the higher grounds,” one 1875 account noted, “that water will not flow to their second stories during the day.”

Those who did have water griped about its quality. “Offensive both to smell and taste,” the National Republican judged the Aqueduct water, and “so impregnated with matter as to be almost unfit for drinking and culinary purposes.” The Surgeon General weighed in as a matter of public health, finding that Washington water contained “more organic matter than that supplied to London from the Thames . . . and was inferior only to certain [samples] from New York harbor.”

The unfiltered Potomac is still quite muddy after heavy rains, and not very appetizing. Photo: Elliot Carter

The unfiltered Potomac is still quite muddy after heavy rains, and not very appetizing. Photo: Elliot Carter

Army Corps of Engineers Major Garrett Lydecker assessed the situation and told lawmakers that the problem lay in Washington’s reservoirs. Limited storage capacity at Dalecarlia and Georgetown left the reservoirs with little dwell time, when particulates had a chance to settle out by gravity. With a fire hose of new water constantly coming into the system, its muddy contents was forced into city pipes prematurely. Adding more storage capacity promised to increase the dwell time and improve the quality of the water.

Lydecker proposed hitting two birds with one stone by placing his new reservoir on the heights beside Howard University. The spot’s high elevation would increase water pressure in the pipes across Washington’s hilly northeastern neighborhoods, and to the increasingly settled areas beyond Boundary Road. An expanded dam at the Great Falls intake would further increase the amount of water traveling down Aqueduct conduits, and an epic new tunnel would carry it across the city from Georgetown to the new lake at Howard University.


Cross-section of the Lydecker Tunnel topography. The tunnel was advanced via vertical drop shafts at Foundry Branch, Rock Creek Park, Champlain Avenue, and McMillan Reservoir. Illustration: Washington Aqueduct/Public Domain

Major Garrett T. Lydecker. Photo: Army Corps of Engineers via  NARA

Major Garrett T. Lydecker. Photo: Army Corps of Engineers via NARA

Lydecker’s suggestions were many orders of magnitude more complex than the tunnel work executed by Montgomery Meigs a generation before. Meigs’ shallow conduits had been largely excavated from the ground level as cut and cover pits, bricked over and reinterred as tunnels. Lydecker wanted to bore a four-mile tunnel more than 100-feet underground, where he thought that walls of bedrock would eliminate the need for costly brick lining.

“There is no reasonable doubt that this tunnel can be carried through solid rock in a direct line between the terminal points,” he told the Secretary of War In October 1882. “Under these circumstances, with the perfected machinery of the present day, its construction would become a simple piece of engineering work.” Lydecker promised that the new tunnel would cost just $530,000.

"A Monument of Fraud"

Hiccups began to appear almost as soon as work began. Surveying towers built at Dalecarlia Reservoir, and on top the roof of Howard University’s Miners Hall were blown down by nasty weather almost as soon as they were completed. Surface surveys continued, with limited accuracy, and outside consultants found “a perfect state … of confusion and chaos.” The Pennsylvania Railroad’s tunnel expert George H. Coryell conducted his own survey and alerted Major Lydecker that the underground headings were drastically out of line. One shaft was on track to miss its connecting point by almost 22 feet horizontally, and 16 feet vertically. Corrections were made and the tunnels realigned.

Workers about to enter the Lydecker Tunnel shaft beside Rock Creek. Photo:  Army Corps of Engineers /Public Domain

Workers about to enter the Lydecker Tunnel shaft beside Rock Creek. Photo: Army Corps of Engineers/Public Domain


Word then came back that the anticipated layer of solid bedrock was in fact “entirely insecure and unsuitable for the purposes of carrying water.” That meant that timber supports would be necessary for the tunneling, and the rotten rock passageway would need a triple-course brick lining if it were ever to carry water. Cost estimates for the Aqueduct extension instantly increased from $530,000 to $993,000.

At the lowest dip beneath Rock Creek, where water pressure from the tunnel’s inverted syphon was at its greatest, thick cast iron walls were required with additional costs attendant. Contracted laborers progressed about four-feet per day through hard and soft rock, back breaking work lit only by torches and glowing mining lanterns. Lydecker made it to February of 1886 before running out of money. Two years of fresh congressional appropriations and missed deadlines followed, with concern on Capitol Hill mounting about the Army Major’s competence and integrity.

Smoke and dust rises from the Rock Creek shaft after blasting. Photo:  Army Corps of Engineers /Public Domain

Smoke and dust rises from the Rock Creek shaft after blasting. Photo: Army Corps of Engineers/Public Domain


By 1888, Lydecker had burned through $2.2 million, prompting exasperated members of the House Appropriations Committee to descend into the tunnel to inspect progress on the costly lining. Lawmakers were horrified at what they found.

The contracts drawn up by Major Lydecker had called for the blasting of a ten to 15-foot diameter passageway, into which a smaller arching brick tunnel was to be carefully constructed. The intervening void between virgin rock and brick was supposed to be backfilled with rubble and mortar for added strength along the long subterranean route.

Inspecting the Lydecker Tunnel lining. Photo:  Army Corps of Engineers /Public Domain

Inspecting the Lydecker Tunnel lining. Photo: Army Corps of Engineers/Public Domain


The Washington Post reported that the congressional inspectors “found that instead of a solid lining, thousands and thousands of feet of the tunnel contained nothing more than a brick arch, with spaces between the sides and the top of the arch and the original rock large enough to drive a coach through.” 

A lengthy congressional investigation later unraveled that Major Lydecker had been negligently overpaying subcontractors, and failed to notice that his inspectors were drawing bribes from fraudulent construction contractors. Lydecker’s lack of personal supervision over the project drew particular criticism, with the Washington Post noting that the Army Major “had rarely or ever gone to the mouths of the shafts, let alone descended into the tunnel itself." (The Army maintains that Lydecker visited the tunnel “about every other week.”)

Two visitors pose inside the completed Lydecker Tunnel. Photo:   Washington Star  /Public Domain

Two visitors pose inside the completed Lydecker Tunnel. Photo: Washington Star/Public Domain


The War Department convened a court-martial, found Garrett Lydecker guilty for his role in the fiasco, and banished him to a remote posting in the Rocky Mountains. Congressional appropriators were so dumbfounded by the experience that they simply abandoned the nascent tunnel project. It would take ten years before Senator James McMillan could convince his Capitol Hill colleagues to dust off their checkbooks and see the “Lydecker Tunnel” through to completion.


In 1898 Army Colonel Alexander Miller brought in new subcontractors, the faulty lining was remedied, and another $1.1 million in bills accumulated. In his Annual Report the new Aqueduct engineer wrote that finishing touches on the Georgetown end of the tunnel included a brick gatehouse to regulate the flow, "covered with Portland Cement plaster blocked off to represent stonework." He didn't mention that the quirky piece of infrastructure was designed to resemble the Corps of Engineers logo on all four sides. Colonel Miller told the Washington Star “he felt ten years younger” when they activated the Castle Gatehouse in 1901, and water finally gurgled down Washington's latest water tunnel.



Go Deeper

"One Year's Work," National Republican, December 2, 1875

"The Water Works Extension: Important Report of Major Lydecker," Washington Star, October 17, 1882

"Longitudinal Section of Tunnel Showing Character of Lining," Board of Experts on Washington Aqueduct Tunnel, January, 1889

"A Monument of Fraud: The Story of Maj. Lydecker's Million-Dollar Tunnel," Washington Post, July 21, 1895

"Tunnel Completed: End of a Work Begun Nearly Twenty Years Ago," Washington Star, November 5, 1901

"The Washington Aqueduct 1852-1992," Harry C. Ways, Army Corps of Engineers, 1996