The public outcry against development has led some opponents to espouse that the density issue is related to Ballard’s stormwater/sewage overflow problem.

Citizens at public meetings have said Ballard’s sensitive sewer infrastructure can’t handle more pressure from an increase in volume. Commenters on the Ballard News-Tribune website have directly noted that sewage will back up in the streets as more and more lots are subdivided and as population increases.

Indeed, Ballard development has already exceeded its target goal of development for 2024 by 317 percent.

It’s true that there are overflows when there is more than one tenth of an inch of rain. So, as Ballard grows in density of population, will the sensitive sewer lines overflow and flood the streets with poo?

The Ballard News-Tribune felt it was time to clear the air.
Susan Stoltzfus, spokesperson for Seattle Public Utilities says that the sewer line capacity is not the issue, but rather, that the issue is stormwater.

“Normally we don’t have sewage back up in Ballard -- we have overflows. That’s how the system was built. 100 years ago when they built the system, they sent the water out to the waterways…Development is not taking any capacity from the system,” said Stoltzfus.

“Because of new laws made in 2009, new structures are not generating any extra runoff…The sewage that is generated by new development is minuscule to the volume of runoff currently happening.”

Stoltzfus explained that since 2009, new laws stipulate that developers have to design new structures to manage their own storm water runoff. To curb runoff, developers are using porous concrete on hard surfaces that leach storm water into the ground (BevMo’s parking lot on Leary Way), rain gardens, and/or buried vaults that store the rain until it can be metered back into the sewer system once the storm passes.

In addition, Stoltzfus explained that since the 90’s, newer homes are built with water conserving fixtures that have actually led to a decrease in wastewater entering sewer lines. For instance, toilets installed before then used seven gallons of water per flush compared to toilets today that use one gallon.

“You can’t blame recent development for sewage issues today. They were addressed in 2009. Really we have to go and fix the structures made before 2009.”

Stoltzfus went further to explain that newer development has actually led to a decrease in pressure in the Seattle sewer system and that the population in Ballard could more than double and the sewer system could handle it. She explained that there was a time when engineers questioned if the sewage had enough volume and pressure to even move through the large pipes.

However, Stoltzfus explained that when uncontrolled volumes of stormwater enter the equation, that’s when there are combined sewage overflows (CSO) in Ballard that blast out into Salmon Bay.

“Even if the sewage volume doubled, the system could handle it, but that’s if we could keep the stormwater out.”

When there are extreme volumes of rain -- like the recent example seen on September 2 where more than .15 inches of rain fell in the first five minutes of the storm—a sewage back up will occur. Stoltzfus said these occurrences are extremely rare.

“When you get that amount of rain in a 24-hour period, as predicted for this storm, the system can handle it. But it all depends on intensity and duration of the rainfall. Each storm is a little bit different. Generally we don’t get sewage back ups in Ballard. This was kind of an anomaly.”

Most of Ballard has a combined stormwater and sewage system, meaning household wastewater meets up with stormwater in the same pipes and flows to West Point Sewage Treatment Plant in Magnolia through the Ballard Siphon. WPSTP treats around 90 million gallons of sewage a day during the dry months, and up to 440 millions during the rain/storm season.

In Ballard, there are overflow sites are at Northwest 24th and 28th streets in Ballard. That water is 10 percent sewage and 90 percent stormwater.

However, there is a part of Ballard—south of 65th—where stormwater and sewage are in separate pipes. This means no sewage is getting into the Bay from these pipes, but that untreated stormwater flows directly into the Bay, carrying a litany of toxins.

Stoltzfus said that the main issue for CSO management is taking preventative measures to keep the stormwater from the street out of the sewer. The best options for older homes and structures are to retrofit or replace fixtures and appliance with water-conserving ones. Also, citizens could divert stormwater from rooftops and other hard surfaces into cisterns and rain gardens. Planting trees and other vegetation also help by acting more like a natural landscape that will soak up water.

“Most people understand that prevention is cheaper than cure.”

Stoltzfus explained that it is more cost effective to install rain gardens and divert down spouts than it is to build larger pipes or “beef up” sewage infrastructure. In fact, making the pipes larger could exacerbate the overflow problem by causing more stormwater to race down the Ballard Basin and potentially causing sewage backups.

Stoltzfus said the answer to Ballard’s overflow issue is rain gardens – lots of them.
SPU’s RainWise actually pays citizens to take responsibility for stormwater falling on their rooftops.

“We have hundreds of rain gardens in Ballard now, but we could use hundreds more. They account for 1.5 million gallons of rainwater and that’s about 300 rain gardens – that is a huge cumulative effect. It’s a sustainable way to manage storm water runoff. So far in Ballard we have had 100 percent satisfaction.”

What’s spurring the action is the 2013 Consent Decree. The City is charged with having no more than one overflow per outfall a year by 2025. To reach this goal, they are building raingardens in 2015 along streets in Ballard and eventually a storage facility near Salmon Bay. The facility will work like smaller underground vaults being used to manage stormwater. The vault would hold the flow until the storm passes and then meter it back into the sewer system to the treatment plant. Currently, SPU is testing soils to find places where such a facility could be built.
Stoltzfus said that anyway to make that vault smaller is a good thing, and therefore, the more people that take action and manage their “down spouts”, the better.

“Half a million to a million gallons in rain gardens will reduce the size of the large structure that will need to built. Once we build the tank, it will be fixed in size and capacity. But, if for some reason we have more rainfall in the future, we could always build more gardens. It is the most resilient technology we have in the face of climate change.”