|Flooding in Bloomingdale July 2012 (via @welovedc)|
Shortly I will publish the second of my three posts on innovation. Yet I must take a quick moment now to highlight the success of one particular example of innovation that just helped the people and neighborhoods in Washington, DC in a very practical way.
This story stems from one of the great precursors of innovation – necessity (“Necessity is the motherhood of invention!”). Many in the Washington region remember we had several (four actually) flooding events in about a two-month period in the Bloomingdale neighborhood and nearby LeDroit Park in 2012. According to our records going back many decades, we had not had more than two flooding events in any single year, and would often go a decade or more without any flooding in Bloomingdale at all. So, four events in a row was unprecedented.
The simple problem is that when the intensity of rain is very high (more than an inch an hour), rainwater pours into sewers that capture and transport both sewage and rainwater to Blue Plains for treatment. This duality explains the name of this type of sewer – which is a combined sewer.
|Flooding in Bloomingdale September 2012 (NBC Washington)|
When enough rain falls, the flow of stormwater into the combined sewer pipes fills them completely. The system is designed to allow overflows out of the overwhelmed pipes. Near the rivers of the city, these combined sewer overflows (CSO’s) discharge directly to the waterbodies, ensuring that millions of gallons of rainwater, mixed with sewage, is in the river. This is certainly a terrible outcome, but a less terrible outcome than having this mixture in basements or city streets.
The huge problem in Bloomingdale, which has combined sewers, is that there are no rivers nearby to accept the overflow when the system is overloaded with rainfall. The extraordinarily unfortunate result is that the flow in the sewers becomes heavy and pressurized – pushing excess flow up and out manholes into streets and back up sewer laterals into homes. In 2012, that is exactly what happened – and many of our customers ended up with sewage and rainwater in their basements, often several times in succession.
|flooding in Bloomingdale July 2012 (Fox 5)|
Our customers were understandably mad. How could this happen? Why has it not been fixed. I hosted a very crowded and difficult public meeting in the basement of a church on a Saturday – and heard over and over again how devastating these flooding events are for our customers.
To be fair to DC Water, there is no easy solution to the problem, or we would have happily implemented it years ago. The mainline sewer that accepts flow from this entire part of the city is called the Northeast Boundary Tunnel Sewer – because when it was built in the 1890s, Florida Avenue was the northeast boundary of the city. Today, Florida Avenue bounds close-in neighborhoods of the city, and huge amounts of development since 1890 fills that land that was once vacant to the north. Yet all that development connects to the same sewer on one hand, and all that impervious cover (roofs, roads, parking lots and the rest) generate more stormwater when it rains. So our old sewer – despite its enormous size (from 7 feet in diameter to 22 feet) – simply can’t handle all the sewage and rainfall if the rain falls fast enough.
One might offer that an obvious solution would be to install a much larger sewer. That is possible, but would require probably a decade of digging up a major road artery in the city from curb to curb and would cost billions of dollars. A new sewer would have to be gigantic and would be below all the other elements of infrastructure in road (Washington Gas, Verizon, Pepco, water mains, other communication lines, etc.). The cost and disruption to the city is simply too great.
This is where innovation came to the rescue. Necessity is clear – we must develop a plan, that can be implemented and paid for, that can keep combined sewer overflows from flooding these neighborhoods and pushing sewage back into basements. The obvious solutions were not feasible. Our team had to be innovative to develop a solution.
And innovate they did – many, many times over. Leading up the point when we finally had a three part plan (short, medium and long-term), we investigated more than 40 different engineering solutions until we came upon one that worked. There was creativity, difference of opinion, solutions that initially seemed to work only to be found inadequate with more analysis – a hotbed of innovation that is probably more like what transpires at Google rather than a water utility. Yet an open approach – that encouraged all ideas, did not frown upon mistakes, and was pushed by necessity – delivered the goods.
|Announcement of Flood Relief Plan in December 2012|
The innovative three-stage solution that we devised, in concert with Mayor Gray and City Administrator Allen Lew, generated positive press, and hope that this long standing problem would finally be resolved (http://www.georgehawkins.net/2012/12/relief-for-bloomingdale-and-ledroit-park.html). The summary is that in the short-run we developed an unprecedented program to financially support homeowners to help them install backwater valves that would keep sewage from flowing back into residences. We also developed an action team to clean storm drains and provide sand bags in high rainfall events. We also funded a rain barrel program to capture rainfall from gutters, and a low impact development project to capture rainfall on one of the main streets that floods.
|A cell at the old McMillan Sand Filtration Site|
Yet it was the medium-term solution where the creativity kicked into gear. The engineering team proposed repurposing century old and abandoned sand filters at the old McMillan water treatment site to hold stormwater during heavy rains. In concert, the team proposed building a piece of a huge tunnel out of schedule to function as a giant underground cistern. Its diameter was designed to be the same as public transit tunnels, so we could buy a used boring machine quickly and get to work.
The long term solution – already on the books in 2012 but not expected to be completed until 2025 – involves drilling an huge tunnel all the way from the Anacostia River into this central part of Washington- again to capture the overflow. This tunnel would connect to the tunnel we already are building along the Potomac and Anacostia to capture the CSOs that do drain directly to these rivers. As part of this plan, we redesigned the tunnel, moved its schedule up three years, and will ultimately connect it to the “cistern” tunnel I mention above.
The short term solutions we implemented immediately. Backwater valves were installed, rain barrels too, and our teams scour Bloomingdale ahead of every major rain. The medium team project moved forward with incredible speed – we wanted the McMillan tank on-line by 2014, and the cistern tunnel (actually deep under First Street) by 2016. Each deadline required us to move faster than we ever have – using emergency procurement authority, design-build approaches, and birddogging regulatory approvals with the city.
As I write this blog, the Washington DC region is experiencing the heaviest total rainfall ever recorded in April. Three to five inches have fallen already, and several more may be on the way. Flooding is a problem all over the region and the warnings persist.
|New Green Infrastructure at Work on Irving Street NW|
And in Bloomingdale, our solutions are working! Not perfectly of course, we still have some local flooding on the streets. But our teams cleaned the storm drains, rainfall was captured in rain barrels, new green infrastructure in several places captured stormwater flow safely – and in a manner that will generate healthy trees and shrubs into the hot summer. And, water flowed for the first time into the tank at McMillan. An innovative idea won out over dozens of others, we figured out how to repurpose the old sand filter, we got it done on time, and it is working! Wow.
|Stormwater in repurposed Tank at McMIllan site|
I have tremendous respect for the people who design and build these projects – and even more important – were creative enough to dream them up in the first place. These solutions by themselves do not solve the problem, and we could still have flooding, maybe tonight or tomorrow. But our enterprise, and the great people who work for it, and doggedly and creatively bringing on-line one solution after another to ultimately solve the problem.
That is innovation worthy of note!