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Inside D.C.'s big dig
Cover Story
Burrowed more than 100 feet under the Anacostia River, a machine the length of one-and-a-quarter football fields and the combined heft of seven-and-a-half Boeing 747s is burrowing along, thrust by thrust, hour by hour, day by day.
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Lady Bird, to be joined later this year by two other TBMs, is digging a 13-mile-long tunnel system that will redirect the roughly 2 billion gallons of overflow a year and send it to the Blue Plains treatment plant instead. The system is expected to eliminate 96 percent of that overflow sewer water and bring an end to the flooding problems in flood-prone neighborhoods such as Bloomingdale.
"We don't worry if it's another house or another small connection, but if you have a huge development farther up at United Medical Center or McMillan or the Old Soldiers Home? Well, we have not been asked the direct question, so we have not given the direct answer — but we were going to have a hard time providing sewer access to a system that already overflows," D.C. Water General Manager George Hawkins said from his office at Blue Plain...
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Shifting mid-stream
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In 2007, the EPA set new limits for the amount of nitrogen that can be discharged from Blue Plains to improve water quality in D.C. waterways and the Chesapeake Bay. Even before Lady Bird's first dig, the authority had to spend about $1 billion to add a new nitrification facility at Blue Plains and to expand the Blue Plains tunnel to meet the higher standards.
Then came 2012, when a series of four heavy storms caused serious flooding in the Bloomingdale neighborhood, a part of the city that has suffered from flooding once every four or five years for the past 60 or 70 years, said Ray, the project director. That prompted D.C. Water to come up with an interim plan to address the issue, converting one of the former sand filters at the McMillan Reservoir into a 3-million-gallon storage tank to reduce flooding during major storms.
It also accelerated the construction schedule for the First Street tunnel, which was moved from 2025 to 2016. The tunnel will be combined with green infrastructure, including a bioretention facility and a pump station that will function as a cistern able to hold up to 10 million gallons until the storm cell passes before sending it on to Blue Plains.
Pre-construction work has already started for the First Street tunnel, which hasn't been easy for neighbors near there, Ray said. It has required a significant excavation to build the shafts to service the tunnels. Construction crews have had to install guide walls blocking off part of Adams Street along the First Street tunnel's path, bring in heavy equipment to drill down for a pumping station to be built on First Street between T and U, even as there's still more drilling and heavy machinery along V Street. At the same time, Ray said, it's the sort of project that qualifies as creating a temporary inconvenience for a permanent improvement.
"There's lots of construction — this is a heavy, civil job right smack dab in this neighborhood — but, you know, these folks have had to endure sewage for years and years," Ray said. "And so, it's been a difficult project. But at the same time the folks we're serving up there, I know they're excited to get finished down there as much as we are."
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