Washington Aqueduct Tunnels, Part III

By Elliot Carter | August 4, 2018

 

By the time the Lydecker Tunnel was nearing completion in 1901, Washington was already clamoring for an expansion of the underground water system. The Washington Aqueduct of Meigs and Lydecker’s day delivered Potomac River water as-is, with only token purification achieved by gravity sedimentation in the city’s receiving reservoir.

The Washington Post once described the Aqueduct water as a “seal-brown mixture of water and real estate.” Another piece half-jokingly described the “semi-solid material oozing from the city water pipes” as appearing to resemble “ chocolate, or coffee, or even a heavy lemonade.” Medical authorities advised residents to always boil the Aqueduct water before drinking it, to kill the ever present typhoid bacteria.

 
 
 The underground vaults created their own weather systems when the sand filters were still in use, with internal clouds and condensation. Photo:   NPS  /Public Domain

The underground vaults created their own weather systems when the sand filters were still in use, with internal clouds and condensation. Photo: NPS/Public Domain

 
 

Shortly before the new reservoir was completed at Howard University, Congress authorized funds in 1901 for an adjacent filtration site to address the public health situation. Like the Lydecker Tunnel, the filter plant was to be an ambitious subterranean undertaking. Sprawling underground vaults, 26-acres in all, housed a vast ocean of sand to filter the city’s water supply like a giant municipal Brita filter.

“Raw water” entered the filters from the adjacent McMillan reservoir, and slowly percolated through the four foot lining of sand. To make the sand sanitary, the Army Corps sourced a top grade supply from Laurel, Maryland and carefully scrubbed it of clay and other undesirable particles. “Every six months a thin layer is removed, then washed in a machine and restored," the Washington Post reported in 1924. "Every two or three years the entire filter surface resanded.” Cleaning the sand was a laborious process that always made up the bulk of the filtration plant’s operating budget, and it was stored on site inside 20 giant concrete silos.

 Twenty unreinforced concrete silos dot the reservoir grounds. The drip drip of water, and ever-present patches of sand still strongly evoke the filtration plant's operational days. Photo: Elliot Carter

Twenty unreinforced concrete silos dot the reservoir grounds. The drip drip of water, and ever-present patches of sand still strongly evoke the filtration plant's operational days. Photo: Elliot Carter

The low-tech sand filters really did work. One study found that the prior to filtration, the Potomac River water “contained between 230 and 740 bacteria per cubic centimeter,” and that city’s new sand filters cut it down to the range of 60-117. Impressed newsmen reported that the “filtration plant is dealing death to germs.” With its background in engineering, its seems fitting that the Army Corps found a mechanical means to tackle the water purity problem rather than using chemicals.

The Slow Sand Filtration Plant came to Washington on the coattails of the era’s City Beautiful movement. Luminaries such as the influential Senator James McMillan believed that there was no separating urban design from the day's social ills. Clean water and leafy parks would increase public health, cut down on crime, and generally enhance the urban experience. It was a time when utilities like water and sewage were regarded as Public Works rather than lowly pieces of sanitary infrastructure.

 
 
 Local newspapers dubbed the fountain at McMillan park the prettiest in Washington. The landscape design was complemented with a perimeter walking path and ample picnic space. Children would often swim in the reservoir and play on its "beach." Photo:  Army Corps of Engineers /Public Domain

Local newspapers dubbed the fountain at McMillan park the prettiest in Washington. The landscape design was complemented with a perimeter walking path and ample picnic space. Children would often swim in the reservoir and play on its "beach." Photo: Army Corps of Engineers/Public Domain

 
 

In keeping with this grand vision, the nation’s top landscape architect was commissioned to beautify the filtration site with a rooftop park. Frederick Law Olmsted Jr. sketched out an opulent green space atop the sand vaults that became an important community gathering place for northeast District residents. Olmsted’s plantings and perimeter pathway were designed to complement the “interesting and remarkable” appearance of the sand storage towers, the walls of which he covered in lush ivy plantings. School children from Michigan (Senator McMillan’s home state) donated mountains of pennies, nickels and dimes to pay for the prettiest fountain in Washington.

For decades the park was a beloved destination for picnics, outdoors activities, and quiet strolls away from the bustle of city life. Walks around the perimeter pathway looked out over a skyline spanning from the Washington Monument to the Capitol dome. Kids playing ball in the park traded stories about the frequent falls down open manholes to a soft landing in underground sand filters.

 
 
 McMillan's sand silos seen in the summer of 2014. During warmer months the silos come alive with lovely ivy plantings left over from the Olmsted landscape design. Photo:   Flickr user David  /CC BY 2.0

McMillan's sand silos seen in the summer of 2014. During warmer months the silos come alive with lovely ivy plantings left over from the Olmsted landscape design. Photo: Flickr user David/CC BY 2.0

 
 

In March 1941, residents opened their newspapers to discover $65,000 in temporary fencing ringing Senator McMillan’s sand park. Fears of hostile “sabotage rings” swept the country in the wake of Nazi submarine aggression, and a newly established Civil Protection Board held emergency meetings to prepare for “the disruption of power, gas, water and sewer facilities.” 

There was little public protest about the closure during the war, or the decade thereafter. A lone Washington Post reporter lamented the sad state of the McMillan Park fountain in 1957. Fenced off from the city, the public oasis had “been left in parts and pieces to the weather and unknown beer drinkers who throw their empty cans at the curved bronze faces of the fountain’s water spouts.”

The years passed in stasis at the fenced off filtration plant, as weeds proliferated in the rooftop park and cracks began to appear in the old concrete sand vaults. In 1986 the Corps of Engineers deactivated the facility after opening of a modern rapid sand filter on the adjacent property. The McMillan plant was offered to the District government with two different sets of conditions. If the city committed to reestablishing the public park they could have the property for a single dollar. Bulldozing the site for commercial development would come with a $9.3 million price tag, fair market value for the real estate in the mid-1980’s. D.C. Mayor Marion Barry chose to pursue the latter option.

 
 
 The vaulted ceiling is punctuated by hundreds of manholes. When the filter plant was in regular operation, Aqueduct employees would dump fresh sand down through the holes, before carefully spreading it out in an even coating. Photo:   Chris Wieland  /CC BY-NC 2.0

The vaulted ceiling is punctuated by hundreds of manholes. When the filter plant was in regular operation, Aqueduct employees would dump fresh sand down through the holes, before carefully spreading it out in an even coating. Photo: Chris Wieland/CC BY-NC 2.0

While yet another 30 year period has passed, the bulldozers and cranes are nowhere to be seen, and McMillan Park remains fenced off to the public. Redevelopment efforts have failed to strike a balance between commercial viability and historic preservation of the old water works. A listing on the National Register of Historic Places in 2013 has added further legal hurdles for the District and developers.

The most recent proposal from Vision McMillan Partners would retain all 20 of the original iconic sand silos, and set aside a generous eight acres of parkland (four times the size of Dupont Circle.) Local opposition, chiefly from the Friends of McMillan Park have vocally protested the suggestion of demolishing all but one of the original underground sand filters. While the old vaults offer a world class destination for urban exploration, crumbling 100-year-old walls made from unreinforced concrete present a potential minefield of personal injury litigation.

 
 
 Sand vaults in the southeastern corner were built on landfill that has settled unevenly and severely damaged their concrete top decks. Structural information was compiled in 2000 and has likely worsened over the past 18 years. Image:  Google Earth /Fair Use

Sand vaults in the southeastern corner were built on landfill that has settled unevenly and severely damaged their concrete top decks. Structural information was compiled in 2000 and has likely worsened over the past 18 years. Image: Google Earth/Fair Use

 
 

A structural engineering study in 2000 found that seven of the filter vaults have already started to collapse, and that their preservation was “not feasible” at any cost. Eleven others are stable or moderately deteriorated, and could be saved for approximately $2 million per vault. (Two other vaults were demolished in the last decade to make way for a yawning drop shaft and DC Water’s Clean River tunnel. Fixing all the salvageable vaults would cost about $22 million, a feasible budget in line with the Canal Park development that cost $20 million in 2012.

Meanwhile, the site remains in limbo as Mayor Muriel Bowser dukes it out with the local activists, and the city weighs whether it wants a historically significant underground sand vault, or a potentially lucrative commercial tax windfall.

 
 

 
 

Go Deeper

"Epidemic of Typhoid - Impure Water Supply is the Cause of the Disease," Washington Post, December 5, 1900

"Turbid Water Supply - Yellow Fluid Not Relished by Members of Congress," Washington Post, March 6, 1902

"Pure Water at Fort - The Muddy Potomac Has No Terrors for Troopers," Washington Post, March 14, 1902

"Bacteria on the Run - Filtration Plant is Dealing Death to Germs," Washington Post, September 12, 1905

"High Grade District Water Result of Careful Controls," Washington Post, September 7, 1924

"Plans to Guard D.C. in Event of Disaster To Be Discussed by Civil Protection Board," Washington Post, February 16, 1941

"Army Moves to Guard D.C. Water Supply," Washington Post, March 3, 1941

"McMillan Fountain Left To Deteriorate in Park," Washington Post, April 9, 1957

"Structural / Geotechnical Engineering Evaluation of the McMillan Filter Site," CC Johnson and Malhortra, PC Enviromental Engineers and Scientists, August 25, 2000