Impervious Area Charge is an integral part of sewer service

Sustainability

Impervious Area Charge is an integral part of sewer service

by Eric Fidler • October 8, 2010 1:46 pm

The Obama administration's decision to to pay an impervious area fee added to all water bills in DC, reversing its earlier position, is a welcome step toward cleaner water.

DC's combined sewer area. Image from DC Water.

DC Water levies the impervious area charge on customers based on the estimated level of stormwater their properties dump onto the streets and thus into the sewers. This is necessary to pay for replacing DC's antiquated Combined Sewer Overflow (CSO) system.

Until 1900, the District installed under every street one pipe to handle both sewage and storm water. Whatever you emptied into your kitchen sink emptied into the same pipe carrying whatever washed along your street's curbs.

The problem is that our sewer system, much like those in other old American cities, simply cannot handle the sheer volume of water that flows through the sewers during heavy rains. As a result, the sewers overflow into Rock Creek, the Potomac, and the Anacostia at 53 outfall points during these storms. As you can imagine, this discharge is neither safe nor pretty.

Rather than dig up every 18th- and 19th-century neighborhood street, DC Water is building several huge containment tunnels to temporarily store sewage-storm "brews" until the treatment plant at Blue Plains can process it all after the storm.

DC Water's CSO plan.

Underground storage tunnels will cost $2.2 billion. To recoup this cost, DC Water started levying a fee on all impervious surfaces on customers' properties, regardless of whether the property is located in a combined sewer area.

Impervious surfaces, such as a house's footprint or a driveway, prevent the ground from absorbing rainwater and slowly releasing it through local springs. Instead, water runs off our roofs, into gutters, down the downspouts, onto a sidewalk or driveway, into the street and then into the sewer. Consequently, storm drains on the street aren't just handling street water, they're also handling the water our homes, offices, parking lots, and driveways dump on the streets.

DC Water is working with the DC Department of the Environment to discount the fee for properties that mitigate their runoff. Until then, we're all paying for our runoff and the tunnels that must contain it.

But is it a fee based on usage, like your water bill, or is it a tax, like a property tax? As you learned in your civics class, no state, and certainly not the District, may tax the Federal Government. The Feds will pay for services provided, such as water and electricity, but they will not pay property and other taxes.

Since this fee is structured to approximate your burden on the sewer system, it shouldn't count as a tax. The Obama administration at first disagreed, arguing it was a tax and that the federal government should not pay.

Most ironically, DC Water's tunnels are being built to comply with the federally-mandated Clean Water Act. In essence, the federal government contributes to the problem, mandates a solution, but refuses to pay for it. This is worse than an unfunded mandate because federal government properties are partly responsible for the problem in the first place.

Without the federal government paying its share, which accounts for 20% of impervious area in DC, water bills for DC residents would soar to compensate for the Feds' "principled" delinquency. One can imagine residents demanding DC Water shut off the water to all government properties; it's hard to stand on principle if it means sitting in a porta-potty.

Congresswoman Eleanor Holmes Norton (D-DC) and Senator Ben Cardin (D-MD) are more diplomatic. They are sponsoring legislation to require the Federal Government to pay.

Fortunately, after a second look, and probably after some hard lobbying, the Government Accountability Office reversed its earlier decision. In a recent letter DC Water provided us, GAO states, "We have concluded that the [Impervious Surface Area] charge is a component of the utility rate customers pay for water and sewer services." That is, the impervious area charge is an integral part of financing a sewer system, that by law must comply with national water quality standards.

26 comments

Tags: Combined Sewer Overflow, DC, DC Water, GAO, impervious area charge, stormwater, water

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Eric Fidler has lived in DC and suburban Maryland his entire life. He likes long walks along the Potomac and considers the L'Enfant Plan an elegant work of art. He also blogs at Left for LeDroit, LeDroit Park's (only) blog of record.

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This is great to see, however it is the responsibility of every homeowner to mitigate stormwater. In an article over at alexblock.net, we discussed that only about a third of the water in the system will be treated by this over 2.2 billion dollar investment by DC Water.

by Doug on Oct 8, 2010 2:14 pm • link • report

Forgive my ignorance but are there any long term plans/efforts to separate the storm sewer runoff from the sewage? Something like, when the combined sewer on a street is replaced that it must be separated? Reducing runoff is good and building the vaults to reduce the storm surge is good but keeping the sewage from the storm water is a big part of the problem.

by EZ on Oct 8, 2010 2:35 pm • link • report

@EZ

The problem is this - what happens after you separate the systems? The storm sewer still has to connect to something. It's very hard to replace it unless you were to do an entire CSO drainage area - and that's a lot of streets. It would likely be far more expensive than the deep tunnel option.

As Doug mentioned, all kinds of low impact development infrastructure can help reduce the amount of stormwater that enters the system, and thus reduce the needed capacity for the deep tunnels, lowering their cost.

by Alex B. on Oct 8, 2010 2:43 pm • link • report

Thanks Alex - what I hear from you is that the deep tunnel option is cheaper in the long run. I'm very familiar with the low-cost ways to reduce runoff - rain barrels, green roofs, modified tree boxes (to absorb runoff from the street), etc.

I guess, what I wonder (and it sounds like it is not being done) is to slowly, over time, separate the systems. Say the system has segments A-B-C-D-Sewer Plant. Segment B might be failing so it gets rebuilt and sewage separated from runoff. I see how the runoff from segment A still runs into B and, until C-D are rebuilt, runoff from B will still be combined. but, eventually C-D will be rebuilt also.

So, perhaps not realistic but I figure if the system is rebuilt incrementally as a separate system, eventually (and I'm talking 50-100 years), it will be separated.

It's kind of like the sidewalk problem - little by little it is being resolved. although maybe I just opened a can of worms with that analogy. :-)

~EZ

by EZ on Oct 8, 2010 2:55 pm • link • report

Typical DC solution. The problem is that the sewer system is outdated, designed poorly and that nobody ever anticipated that it needed to be replaced. The solution? Impose a fee!

Truly, the real solution would be for the Capital of the Free world to design and build a 21st century system that could sit for another century or so.

For anybody who wishes to argue that a century is long-term for a sewer system, I'll point out that the French are still working with their sewer system from 1370 in Paris. It was built initially to protect the drinking water from the river. They solved a problem we're now dealing with 640 years ago.

BTW: That same sewer system in Paris is where the Phantom of the Opera dwells, and where if I am not mistaken, much of Paris' free WiFi hot spots have been hidden in.

by Jasper on Oct 8, 2010 2:57 pm • link • report

"The problem is that our sewer system, much like those in other old American cities, simply cannot handle the sheer volume of water that flows through the sewers during heavy rains."

friday snark: Technically, the pipes can handle that much. It's just when we decided to start treating it we ran into scaling problems.

by snark on Oct 8, 2010 2:57 pm • link • report

I hope there's a plan to separate the storm water lines at some point in the future, if only because it would be nice to walk down the street on a hot summer day in DC without smelling sewage.

by Anonymous on Oct 8, 2010 2:59 pm • link • report

@EZ, it's not quite that easy. To separate stormwater from sanitary, you effectively have to build a parallel system of pipes. To do that for each "section" you speak of means digging up and laying an entirely separate and parallel pipe system for the entire "section". That means digging up every street in the area to lay new pipe, in addition to fixing or repairing any existing infrastructure. Most cities that have looked at it have determined it is simply too expensive compared to creating temporary storage basins to hold the excess water during heavy rains.

by Fred in RVA on Oct 8, 2010 3:12 pm • link • report

One thing to remember - regular storm sewers aren't treated at all and just dump into rivers all the time. One advantage of a combined system is that under light rain, all that runoff is treated at Blue Plains before entering the rivers.

So, separating storm sewers from sanitary sewers isn't a silver bullet - there's still a strong desire to reduce run-off.

That said, simply replacing all of the CSO pipes is a completely unrealistic project to be completed in any sort of reasonable timeframe. That's why we have the deep tunnel concepts.

DC Water's plans do involve separation of the sewers for some small CSO outlets:

http://www.dcwater.com/workzones/projects/pdfs/rock_creek_sewer_seperation_b.pdf

However, the long term management plan has deemed that approach unrealistic for most of the CSO area:

http://www.dcwater.com/workzones/projects/pdfs/ltcp/Control_Plan_Highlights.pdf

Page 9 of that PDF shows the areas where the sewers will be separated. The remaining areas will be addressed in other ways.

by Alex B. on Oct 8, 2010 3:13 pm • link • report

@ Jasper The Paris system has the exact same combined sewer problem as DC. Their solution up until now has been the exact same DC's - during heavy rain, dump the sanitary sewage in the Seine. They are now trying to reduce the number of CSO discharges, just like DC.

by jcm on Oct 8, 2010 4:25 pm • link • report

hmmm ... So, if we can get rid of the overflows ... won't that mean that we also won't have plastic bags making their way via the sewers to the Anacostia? Maybe we could drop the bag tax now that we're already paying for this cleanup via the impervious surface charge? ... Nah, probably not ... Once these Councilmembers come up with a new tax, they always find a way to spend the revenues ...

by Lance on Oct 8, 2010 6:59 pm • link • report

incidentally, other than being 'yucky', what are the consequences with having the sewage back up into the river those 2 or 3 times a year when when there's a really heavy storm? It sounds like all cities have been doing that for hundreds of years now. This is an expensive project. What are the benefits?

by Lance on Oct 8, 2010 7:01 pm • link • report

Most of the bags in the Anacostia come from non CSO systems. A large pat of the watershed in DC is not part of the CSO area. In these area the ares the separate stormwater pipes dump directly from the streets/parking los into the river so the blue planes interceptor will provide no reduction in the number of bags entering the river from a good portion of the watershed.

by W. on Oct 8, 2010 7:19 pm • link • report

Lance, it will take 20-30 years to finish all those deep tunnels. So, maybe then we can talk about removing the bag tax.

That said, remember that storm drains in the non-CSO area still dump right into the river. That area still covers 2/3rds of the city.

And you're really asking what the problem is with dumping raw sewage into our rivers? Really? Really?

And we're not talking 2 or 3 times a year - more like 70 times a year we end up getting enough rain to trigger a CSO event from at least one of the many CS outlets.

by Alex B. on Oct 8, 2010 7:31 pm • link • report

@Alex And you're really asking what the problem is with dumping raw sewage into our rivers? Really? Really?

Yeah, really really. Other than the yuck factor ... Can you please explain how 'natural fertilizer' is bad for the environment? Is it 'too much of a good thing' for plants down stream? ... Does it knock the pH balance off? There has to be some good reason to spend so much money for other than 'the yuck factor' ... I'd hope. Someone must be able to explain it .. I'd hope. Or, is it like the bag tax and 'oh well, it HAS to be good for the environment, doesn't it?'

by Lance on Oct 8, 2010 7:54 pm • link • report

We're not talking about yucky as in your parents make you eat your asparagus, we're talking yucky as in unhealthy and unsanitary. Surely you're aware of the medical dangers of raw sewage - the bacteria and diseases that can spread, etc.

As for a good reason, we're paying for it because we're mandated to by the EPA and by the clean water act.

by Alex B. on Oct 8, 2010 8:04 pm • link • report

@Lance: Seriously? Are you playing ignorant to get a rise out of people?

Let's set aside the presumably self-evident public health issues associated with dumping raw sewage into a waterway.

The mechanism at work is nutrification. The nitrogen and phosphorous in sewage - "natural fertilizers"- encourage the explosive growth of algae in bodies of water, removing oxygen from the water and blocking sunlight, killing underwater plants and asphyxiating aquatic life. Insufficiently treated sewage contributes to the destruction of the Bay's ecosystem, its fisheries, and the people whose livelihoods depend on them.

If you want to say that this is perfectly fine, than do so. Challenge the policy decisions that environmental advocates propose, in response to nutrification, by all means, but please try to pretend that the problem doesn't exist.

by David R. on Oct 8, 2010 8:17 pm • link • report

I used to think it was a fee, but when I got my notification it looked suspiciously like a tax and, worse, a capricious one. The charge is based on the supposed impervious area of a property (roof, driveway, front walk, etc.) but without any regard to what happens to the water that falls onto those surfaces. Sure, if the driveway channels to the street that's one thing, but what if that roof goes into rain barrels, or the downspouts go into water gardens? Or if the patio simply slopes the water into the lawn? Or if the driveway has pervious pavers? None of that is taken into account at this point--it's just the raw square footage of non-pervious surfaces.

by ah on Oct 8, 2010 9:22 pm • link • report

ah,

You're right that the fee is not perfect. In fact, when it was first proposed, WASA (now DC Water) promised to discount the fee to properties that included features like rain barrels and rain gardens. When I last checked their website to write this, they said the discount mechanism was not in place yet. That's disappointing, but I trust they will keep to their word.

That said, it's impressive that DC Water has gone to great lengths to attach the fee to something that approximates a customer's impact on the system. Usually water utilities charge sewerage fees based on the amount of tap water bought. Rather than raise the sewerage rate based on tap water bought, this fee uses newer GIS technology to closer match the property's burden to property's fee.

I still oppose the bag tax because it levies a tax without any regard to whether the purchaser drops it as litter or disposes of it properly. In fact, I'd assume the vast majority of bag users don't litter. The impervious area fee is much more nuanced in that it's based one some scientifically measurable, though imperfect, estimate of the actual externality of individual, not collective, action.

Though the impervious area fee is certainly not perfect, it's a laudable attempt to match the fee to the externality as closely and practicably as possible.

by Eric Fidler on Oct 8, 2010 10:09 pm • link • report

@Erik I still oppose the bag tax because it levies a tax without any regard to whether the purchaser drops it as litter or disposes of it properly.

Erik, I apologize for everything/anything I said earlier. You're my friend :)

@David R @Lance: Seriously? Are you playing ignorant to get a rise out of people?

well ... yes ;)

it is after all a Friday evening ... a BEAUTIFUL Friday evening!

enjoy, one and all!

by Lance on Oct 8, 2010 10:36 pm • link • report

And Eric ... I apologize for calling you Erik ...

by Lance on Oct 8, 2010 10:37 pm • link • report

So WASA is going to be charging people REGARDLESS of whether they've done their own mitigation of runoff? So use of rain barrels are irrelevant to WASA's money grab?

by fritz on Oct 9, 2010 11:15 am • link • report

@ Erik - How is a fee/tax that doesn't consider whether you dispose of a bag properly significantly different from a fee/tax that doesn't consider whether you dispose of rainwater properly?

In either case there are costs to tying the two more closely to the improper behavior, but why does WASA promise they will take account of these things but not implement them more immediately, or at least give property owners the opportunity to demonstrate that their GIS-identified impervious areas actually overstate their contribution to runoff?

Sure, there are probably great areas of the city where the two make a good match--essentially anywhere where there are limited yards (condos, row houses, etc.). But I happen to live where we have a decent amount of yard/garden around the house and the water runs off into that, not to the street.

by ah on Oct 9, 2010 11:56 am • link • report

@ah -- of course I don't know about your particular circumstances. But in general, yards and gardens also contribute to run-off, although not as much as paved surfaces. This is a major reason why there are lawn chemicals in the waterways.

by Miriam on Oct 9, 2010 12:29 pm • link • report

How about some discussion of the Casey Trees report of 2007
The Green Build-out Model: Quantifying the
Stormwater Management Benefits of Trees and
Green Roofs in Washington, DC
The strong option would negate the need for those tunnels but require developers to put green roofs on all new construction and any large scale roof replacements.
Toronto mandates green roofs why not DC
Swizterland requires all new buildings to replace the green surface they have built over

by danmac on Oct 9, 2010 4:21 pm • link • report

@danmac: Even if green roofs were mandated, they would apply only to new construction, not to the thousands of existing buildings.

Now, if there were sufficient tax benefits for the installation of green roofs on existing buildings, maybe that would have a greater impact.

by Fritz on Oct 9, 2010 6:39 pm • link • report