Greetings Bloomingdale/LeDroit Park Residents:
Please read the below letter from our General Manager, Mr. George Hawkins, posted to the Bloomingdale/LeDroit Park web page just today!
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Bloomingdale/LeDroit Park Community Update – October 5, 2012
Bloomingdale and LeDroit Park Customers,
The following is an update on our ongoing work to mitigate the sewer backups and flooding that affected your neighborhoods this summer.
Last Week’s Meetings. I testifiedat last Tuesday’s hearing of the Council Committee on Environment, Public Works and Transportation. At that hearing, we heard from a number of you about the problems you’ve faced in your own homes – both recently and in past years. As I have said in the past, I don’t want a single customer to go through this again. We have an unprecedented number of staff working on various pieces of this issue, and we’ve already started generating results. The Mayor’s Task Force on the Prevention of Flooding also met last Thursday, and the committees have been meeting on a regular basis as well. The presentation from the Technical Committee on short-term options for roadway flooding is here.
Intermediate Solutions.We are still intensively looking at a number of medium-term options that would bridge the gap between now and our Clean Rivers Project in the long-term. You have probably seen discussion in hearings, meetings and news accounts about the possibility of using part of the former McMillan Sand Filtration site to store excess stormwater or combined sewage from the Northeast Boundary Drainage Area. Our engineers continue to assess several scenarios on this site and elsewhere, for storage and sewer diversion. We don’t want you to pin hopes on solutions that aren’t feasible, so we are working intensely behind the scenes for now.
Historical Perspective.On our website, you can now find the complete historical collection of engineering studies of the Northeast Boundary and the entire sewer system. We have also received a number of questions from those of you who are wondering why the federal government or our predecessor agencies did not expand the portion of the Northeast Boundary that runs through Bloomingdale and LeDroit Park. Here is a brief answer.
This is a 6’-6”x 9’-9” sewer running directly underneath Florida Avenue. Expanding the sewer itself would require breaking the pavement, carefully rerouting or digging around all of the other utilities that went in the ground on top of the sewer since the 1890s (including gas, electric, telephone and water), constructing a parallel relief sewer, and adding new storm and wastewater connections to the relief sewer before putting everything back in place above it. Florida Avenue, which is a major commuter artery and connects several commercial corridors, would be closed in its entirety for months if not years. The project would cause similar traffic, noise and disruption to the construction of Metro’s Green Line in the late 1980s.
A tunnel underneath the neighborhood to provide the sewer system with extra capacity is a far better solution. As you know, our long-term plan is called the Clean Rivers Project, and the flood-control portion for the Northeast Boundary is scheduled to be operational in 2025 if not slightly sooner. As to the timeline on that project, modern earth pressure balance tunnel boring machines that make tunneling practical without causing excessive settlement first became available in the mid-1990s. Planning efforts for a tunnel system to address combined-sewer overflows into the District’s waterways began in 1998, with a draft plan released in June 2001. Then-DC WASA began seriously evaluating a flood relief tunnel after severe storms on August 11, 2001 caused flooding in many places, including along the Northeast Boundary. The agency decided to modify the location and layout of the proposed Anacostia River tunnel system to address both flood relief and combined sewer overflows into the river. The final long-term control plan was approved by court order in March 2005, and work has been underway on the tunnel system (including the flood-control piece) ever since.
In 2006, in response to a storm that caused flooding in many areas of the District including Bloomingdale, then-WASA commissioned an engineering study on the sewers in the neighborhood. The study recommended several block-level improvements that the agency ultimately made in conjunction with the District Department of Transportation, and also recommended backflow preventers and overland flooding prevention techniques for individual homes. DC Water began offering rebates for the preventer valves and engineering consulting services as a response to the storm events of 2012.
Rainfall Analysis.We recently uploaded our engineers’ analysis of 2- and 6-hour rainfall events since 1948. By putting the graphs online without explaining how we chose which data to include, we brought in a number of questions and comments. Our explanation follows, and we have added it to the analysis on our website.
The last page of analysis shows actual rainfall data collected at DC Water’s Bryant Street rainfall gage during the July 10, 18, 19 and Sept 2 floods. The rainfall from these gages was compared to rainfall return frequency dataavailable from the National Oceanic and Atmospheric Administration (NOAA) at. The data show that:
· The July 10 storm has a nearly 10-year NOAA recurrence interval for 15-min duration storms
· The July 18 storm has a nearly 5-year NOAA recurrence interval for 30-min duration storms
· The July 19 storm has a nearly 5-year NOAA recurrence interval for 15-min duration storms
· The Sept. 2 storm has a more than 10-year NOAA recurrence interval for 2-hour duration storms
The first two graphs show historical rainfall data from the National Weather Service rain gage at Ronald Reagan National Airport. Two-hour duration and six-hour duration storms were analyzed to determine the frequency of storms since 1948. The data show that storms have been episodic (example: the 1950s had many intense storms, but the 1990s had comparatively few storms of 2-hour and 6-hour durations). The data also show that there have been years in the past when multiple intense storms have occurred in the same year (example: 1953 had three 2- to 5-year storms of a 2-hour duration in the same year).
In each graph, we plotted the Bryant Street rainfall gauge totals for the July 10, 18, 19 and Sept 2 storms. This is a different dataset and was plotted to allow comparison of rainfall totals to past events. I apologize for any confusion we might have caused earlier.
Online Chat.District Department of Transportation Director Terry Bellamy, who is also a member of the DC Water Board and the Mayor’s Task Force, will host an online chat at noon on Wednesday. The purpose of the chat is to hear directly from residents about drainage problems in the Bloomingdale and LeDroit Park neighborhoods. Residents from these neighborhoods are invited to join or follow the discussion on the web at ddot.dc.gov/chatlive. The chat is intended to identify areas that are in need of infrastructure improvements because stormwater ponds in the roadway or bypasses catch basins, or where the catch basin isundersized.
Homeowner Consultations and Backflow Preventer Rebate Program. Engineers from Arcadis have visited 40 homes to provide advice on how to prevent overland flooding. We have received and processed four backflow preventer rebate requests to date. We have also uploaded the presentationand videofrom the two homeowner workshops conducted by the International Association of Plumbing and Mechanical Officials.
Rain Barrels and Cisterns.We have mailed out and distributed several thousand flyers about our rain barrel and cistern subsidy program through the District Department of the Environment (DDOE). DDOE has already completed 44 homeowner assessments, which are the first step toward receiving a free barrel or cistern, and has 20 more scheduled for next week. The devices will begin arriving in mid-October. We are offering the first round of consultations and installations to those whose homes are eligible for a backflow preventer rebate, but will extend the boundaries of the program if funds allow.
Sewer Inspections.Using television cameras or walking the sewers where possible, DC Water contractors have inspected 57,460 linear feet out of a total 108,776 feet, indicating that our inspection is now about 53 percent complete. We plan to extend our inspection area to include the McMillan reservoir area next week. We are attempting to complete the original area by the end of this month as we’ve said in the past, but have had some difficulty accessing manholes because the emergency no-parking signs have disappeared. We would appreciate your help in making sure your neighbors follow the signs so we can get into the sewers to inspect them.
We will have much more to report in the next days and weeks. Enjoy the weekend.
Sincerely yours,
George S. Hawkins
General Manager
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