District of Columbia Water and Sewer Authority - Environmental Stewardship

Environmental Stewardship

At Blue Plains, wastewater treatment goes beyond primary and secondary treatment levels, to tertiary (or advanced) treatment. The effluent that leaves Blue Plains and is discharged to the Potomac is highly treated and meets some of the most stringent NPDES permit limits in the United States.

Historically, wastewater treatment plants have contributed nutrients such as phosphorus and nitrogen to the waterways in which they discharge. These nutrients have been found to deplete oxygen in the marine environment, a process that is detrimental to fish and other aquatic life.

Since the mid-1980s, Blue Plains has reduced phosphorus to the limit of technology, primarily in support of water quality goals of the Potomac River, but also for the restoration of the Chesapeake Bay. The Chesapeake Bay Agreement, reached in 1987, was a first step in reducing nitrogen discharge to waterways that are tributary to the Chesapeake Bay. Under the agreement, the Bay states and the District committed to voluntarily reduce nitrogen loads by 40 percent from their 1985 levels. Blue Plains was the first plant to achieve that goal. Furthermore, in every year since the full-scale implementation of the Biological Nitrogen Removal (BNR) process was completed in 2000, Blue Plains has every year successfully achieved and exceeded that goal of a 40 percent reduction. In Fiscal Year 2009, the BNR process at Blue Plains reduced the nitrogen load by more than 58 percent.

DC Water and EPA agreed upon new nitrogen limits as part of the NPDES permit. effective September 2010. reducing nitrogen levels to 4.7 million pounds per year. DC Water plans to achieve these levels by constructing new facilities at Blue Plains to perform enhanced nitrogen removal (ENR). The total cost of the project is nearly $1 billion.

In FY 09, the Authority rehabilitated pumping equipment and accessories in one of two stations that pump incoming wastewater into the plant and replaced aged infrastructure and equipment in the plant’s final filters with a more effective system. All the upgrade projects were tied into the plant-wide process control system (PCS), which monitors and controls the plant’s processes from a central location.

Progress was achieved in implementing the nitrification/denitrification facilities upgrade to convert nitrification reactors from coarse to fine bubble diffusion and to modify structures and equipment. The rehabilitated and new equipment will support other ongoing upgrades to the nitrification/denitrification process, and aims to meet the nitrogen reduction goals of the Chesapeake Bay Program. It will also increase energy efficiency.

On the waterways, the Authority operates two skimmer boats that remove floatable debris from the Anacostia and Potomac rivers every Monday through Friday. These crews remove more than 400 tons of trash from our waterways each year.

Plastic bottles, plastic bags, inflatable toys, baseballs and environmental debris like tree limbs, are all skimmed from the waterways and deposited into oversized dumpsters for removal. In decades past, there used to be larger items, such as sofas and refrigerators. But over the years, the skimmer boats have removed most of those. Still, there is the occasional unlikely item, such as the live deer that was recently rescued to dry ground.

In addition to their full-time work assignments, these crews clean the way for special events like the Nation’s Triathlon and high school crew competitions, as well as for conservation efforts.

As a result of the work DC Water contributes, “The District, as a city, is head and shoulders above any other municipality in the Bay watershed,” said Tom Schueler of the nonprofit Chesapeake Stormwater Network. In 2009, The Stormwater Network developed a stormwater performance grading scale in which the District received the highest grade of B+ and others went on score as low as Cs and even Ds.