question to DC Water on flow regulators

From: Emanuel D. Briggs <Emanuel.Briggs@dcwater.com>
To: Jeremy Fegley
                    

Bloomingdale/LeDroit Park Residents:

                     

Please see below the response to Mr. Fegley's inquiry regarding combined sewer overflow:

                     

Combined Sewer Overflows (CSOs) are regulated by the EPA, and DC Water operates and monitors the hydraulic controls of the sewer system in accordance with provisions of the Clean Water Act. DC Water does not operate the sewer system in a manner that gives preference to pollution reduction instead of flooding relief. Nothing in DC Water’s permits issued by EPA requires or envisions allowing for sewage backups or surface flooding of combined sewers to occur as part of the operational strategy for limiting CSOs.

                 

The network of inflatable dams, flow regulators and sewers throughout the City’s combined sewer area act together to limit overflows and to convey runoff from streets and structures. During smaller rainfall events, the inflatable dams hold back flow to create temporary storage within the pipe to control overflows. This only occurs during small events. During large rainfall events, the dams are deflated and combined sewer flows are discharged freely to the rivers. The system has been designed to operate in this manner. Under these conditions, the discharge is limited by physical size and slope of the pipes in the system. Sewer backups and surface flooding that occur during these extreme rainfall events result from localized sewer system limitations that are independent of hydraulic controls operated to limit overflows to the river during small rainfall events.

              

Emanuel D. Briggs |Manager, Community Outreach, External Affairs | District of Columbia Water and Sewer Authority | emanuel.briggs@dcwater.com

5000 Overlook Avenue, SW | Washington, DC 20032 | (202) 787-2003 | (202) 341-7952 (cell) | (202) 787-4122 (fax)

                                                          

From: Jeremy Fegley  

Sent: Thursday, September 06, 2012 8:50 AM
To: Emanuel D. Briggs

One question regarding the handling of Combined Sewer Overflow in the Combined Sewer System.

DCWater's website notes:

"During periods of significant rainfall, the capacity of a combined sewer may be exceeded. When this occurs, regulators are designed to let the excess flow, which is a mixture of storm water and sanitary wastes, to be discharged directly into the Anacostia River, Rock Creek, the Potomac River, or tributary waters. This excess flow is called Combined Sewer Overflow (CSO). Release of this excess flow is necessary to prevent flooding in homes, basements, businesses, and streets. Typical regulator operation during wet weather is shown here [http://www.dcwater.com/wastewater_collection/css/default.cfm]."

Would you say that the rains we have experienced over the last few months have exceeded the capacity of the combined sewer system? If so, did the 'regulators' not do their job and allow the excess flow discharge as noted above? The above states this release is necessary to PREVENT FLOODING IN HOMES, BASEMENTS, BUSINESSES and STREETS.

So then why do we keep flooding?

J. Fegley

T ST NW