In 2011, Washington, D.C. broke ground on the $2.6 billion Clean Rivers Project, the city’s largest construction project since building the D.C. Metro.
The Clean Rivers Project requires a massive infrastructure installation and accompanying support program that will effectively reduce combined sewer overflows (or CSO) in the District’s waterways: the Anacostia and Potomac Rivers and Rock Creek.
As in many older cities, about one third of the District of Columbia has a combined sewer system. During heavy rains, the mixture of sewage and storm water cannot fit in the existing sewer pipes, and both sewage and storm water flow into the nearest body of water.
In the 1950s, 60s, and 70s, portions of the combined sewer system were separated to reduce CSO, and in the 80s and early 90s new facilities to control combined sewer overflows were constructed. However, about 2.5 billion gallons of combined sewage currently flow into the Anacostia and Potomac Rivers and Rock Creek in an average year as a result of combined sewer overflow. Managed by the District of Columbia Water and Sewer Authority, the Clean Rivers Project will reduce CSO by 96 percent.
This project is the result of a 2005 Federal Consent Decree entered into by DC Water, the District, the U.S. Environmental Protection Agency, and the U.S. Department of Justice. The Project meets court-ordered CSO control requirements and water quality standards and includes a 2025 deadline to implement the project in its entirety. Similar CSO tunnels exist in Chicago, IL; Indianapolis, IN; and Atlanta, GA.
The project goes a long way in providing sustainability for the region, making waterways healthier and cleaner and addressing localized sewer issues from a century of urban development. The new sewage system will capture and clean water during heavy rainfalls before waste water can reach rivers, creeks, and ultimately the Chesapeake Bay.
A Lady Bird Legacy
To achieve this complex environmental goal, DC Water will implement a system of tunnels, sewers, and other diversion structures to control and capture overflow throughout the city. The size of the construction project is massive. Enormous underground tunnels will store the combined sewage during rain events, releasing it to the Blue Plains Advanced Wastewater Treatment Plant after the storm subsides. The Blue Plains Tunnel alone requires the installation of 24,300 linear feet of tunnel and the construction of a dewatering shaft (132-feet in diameter) in addition to drop, screening, and overflow shafts.
To create the gigantic underground structures, giant tunnel boring machines (TBM) are used to bore Metro-sized tunnels more than 100 feet underground. The first machine to arrive at DC Water has a 26-foot diameter and measures more than a football field in length when fully assembled. This TMB is being used to dig the first portion of the Project known as the Blue Plains Tunnel, a four-mile section of the 13-mile Anacostia River Tunnel.
TBMs are named and christened much like boats. DC Water’s TBM was named “Lady Bird” after Claudia Alta “Lady Bird” Johnson, First Lady and wife of President Lyndon B. Johnson. When her husband became president in 1964, Lady Bird made it her mission to preserve and protect the environment. She encouraged her husband to declare the Potomac River “a national disgrace,” which drew attention to the declining health of America’s waterways and was a catalyst for the eventual Clean Water Act of 1972.
After being christened with D.C. tap water, “Lady Bird” was lowered underground and began tunneling in July 2013. You can follow her journey under Blue Plains, along the Potomac and up to the Anacostia River at dcwater.com/workzones/projects/Lady_Bird_TBM.cfm and on Twitter at @LadyBirdTBM.
Public Involvement
Responsibility for the construction project lies with DC Water; however, a large portion of the project facilities are located on or beneath National Park Service lands. The NPS and DC Water are co-lead agencies in the development of an Environmental Impact Statement which will evaluate potential impacts of the construction of the Clean Rivers Project on the natural, cultural, and human environment.
Public involvement in the EIS process is a requirement, and DC Water will hold public meetings to share information and receive public comments on the proposed Project. A public comment period was in effect until September, 2014, and an additional comment period will take place after the findings of the EIS are publicly released.
A Drop’s Life
You can learn more about the Clean Rivers Projects at dcwater.com/workzones/projects/longtermcontrolplan.cfm.
To learn about the project from the perspective of a single water drop, go to youtube.com/watch?v=5Ug1hravb9Q&feature=plcp.
by Cynthia Houston
