Wastewater Integrity: Baltimore City’s Sustainable Path After Consent Decree
Older U.S. cities like Baltimore, Washington, and Philadelphia share many of the same traits – charm, history, a vibrant waterfront, and typically a sanitary sewer system that has been in service for 100 years or more. While these systems may have been state-of-the-art in the 1880s, they were struggling to keep pace by the end of the 20th century as cracked sewer lines and leaky joints allowed sewage to leak out, breaking pipes, flooding basements, and causing overflows into streams and drinking water sources. This inflow and infiltration (I/I) problem in pipelines is much more severe for combined systems in Washington and Philadelphia, where sanitary sewerage and stormwater flows in the same pipe.
Beyond an aging infrastructure, large U.S. cities were dealing with new, stricter federal regulations which mandated system upgrades. The Clean Water Act of 1972, for example, required municipalities to restore and maintain the chemical, physical, and biological integrity of the nation’s waters by preventing pollution, improving wastewater treatment, and maintaining the integrity of wetlands. The Safe Drinking Water Act set standards for public drinking water quality in more than 160,000 public water systems nationwide.
To deal with this perfect storm of increased federal regulation, failing infrastructure, and greater demand from a growing regional population, these cities frequently have entered into consent decrees with the U.S. Environmental Protection Agency and state Departments of the Environment to inspect, identify, and improve the entire sanitary sewer system. In Baltimore’s case, this meant a 2002 agreement focused primarily on system improvements to eliminate sewage overflows.
With approximately 1,400 miles of sewer pipes serving about 1.6 million customers, Baltimore system improvements began with a sewer system evaluation survey to locate and determine the condition of all manholes and underground pipelines and assess where fixes needed to be made. The next phase of this initiative – expected to continue until 2020 – focuses on design and construction projects to produce cleaner streams and waterways, more stable water and sewer rates, and, ultimately, a more welcoming environment for industries that depend on a reliable urban infrastructure.
While many of these fixes are routine, Baltimore has also worked with companies like EBA Engineering to implement more innovative strategies, including green infrastructure (creating areas such as wetlands and swales around parking lots to divert rainwater away before it ever gets into the pipes) and rehabilitation of existing pipes using CIPP (Cured in Place Pipeline, which, using trenchless technology, creates a seamless, pipe-within-a-pipe).
What does all of this mean to the average Baltimore City resident? With current repairs estimated at nearly $1 billion, the consent decree to date has produced numerous improvements, including:
- Elimination of 60 engineered sewage overflow structures
- Improved operations and maintenance for the sanitary sewer system
- Completion of 39 specific consent decree projects on schedule, at a cost of over $300 million
- Upgrades enabling the Jones Falls Sewage Pumping Station to pump 55 million gallons per day (it previously pumped 35 million gallons per day)
- Construction of the 20 million gallon per day Stony Run wet weather sewage pumping station
- Separation of the Forest Park and Walbrook combined sewer systems
- Upgrades in Baltimore’s GIS and mapping database
- Reduction in wet-weather related sewage overflows citywide.
In addition, Baltimore’s two treatment facilities now treat approximately 250 million gallons of wastewater daily, removing contaminants and returning the water to natural waterways. While the work continues, wastewater problems in cities like Baltimore are gradually being addressed, vastly improving the quality of life for residents and visitors alike.