Blog

CodeNext: Less Flooding, Cleaner Creeks

By Brian Zabcik
Clean Water Advocate

Testimony by Brian Zabcik before the Austin City Council, 5.29.18

Environment Texas believes that taken as a whole, CodeNext will lead to new development in Austin that will be better for the environment. The city’s current Land Development Code encourages low-density sprawl, which in turn encourages our reliance on cars and trucks that produce the emissions that cause climate change. CodeNext will encourage higher-density development, which in turn will make mass transit and other low-emission transportation alternatives more feasible.

We also believe that CodeNext’s changes to Austin’s stormwater policies will be much better for the environment. They will upgrade our regulations to progressive stormwater standards that are increasingly common in other large American cities. This should be one of the consensus areas in CodeNext that all Austinites can agree upon.

Stormwater is just another word for runoff, and runoff is a problem because of impervious cover. Roofs and paved surfaces can block rain from soaking into the ground where it falls. More impervious cover increases the quantity of runoff, which can lead to flooding. But impervious cover also decreases the quality of runoff. When rain flows over surfaces, it picks up whatever's on those surfaces — roofing chemicals, automotive fluids, litter, pet and wildlife waste —and then carries these pollutants into our streams and lakes.

CodeNext’s stormwater policies will result in less flooding, cleaner creeks, and more water conservation. Less flooding, because redevelopments will now have to meet the same drainage requirements as new developments. And less flooding, because all new developments will have to keep runoff at pre-development levels. Cleaner creeks, because new developments will have to use green infrastructure like rain gardens to filter pollutants from runoff. And more water conservation, because rain harvesting systems will store rainwater for later use, which will help as we face more droughts.

Austin’s stormwater policies are split among three sections in the Land Development Code. The Drainage section (Article 23-10E) deals with the problem of runoff quantity. The Water Quality section (Article 23-3D) deals with the problem of runoff quality. The Landscape section (Article 23-4E) contains some additional stormwater regulations. All of these policies only affect multifamily and commercial developments and don’t apply to single-family houses. 

CodeNext contains two major changes to the Drainage section. One, it will eliminate the redevelopment exception in the current code. This exception says that if a redeveloped property doesn’t increase the existing amount of impervious cover, it doesn’t have to meet current drainage requirements. This is a problem for all properties built before 1974, because the city didn’t have any drainage requirements before then. Under the current code, if you redevelop one of these old properties and you don't change the amount of impervious cover, you still don’t have to provide any drainage improvements. CodeNext will get rid of this loophole.

The second major change in the Drainage section will create a new standard referred to as the pre/post rule, which will require that post-development runoff conditions be maintained at pre-development levels. The criterion will be the peak flow rate — the maximum amount of runoff flowing away from a property at any one time. In other words, when you develop a property, you can't make runoff worse than what would have happened on the property in its natural state. 

Because some developments with lots of impervious cover will inevitably produce more runoff, they will still be able to help improve drainage throughout the city, since there will be three ways to meet the pre/post rule. One, by including onsite detention features such as a detention pond. Two, by constructing improvements to the city’s drainage system. And three, in limited instances, by paying a fee-in-lieu to fund improvements to the city’s drainage system.

While all cities have drainage requirements, Austin is one of the few to have water quality requirements. Our policies evolved in the series of watershed ordinances that the city adopted in the eighties and nineties. One goal of these ordinances was to reduce the amount of dirty runoff that flows into our streams, lakes, and springs. Dirty runoff is one of the main reasons why eight Austin creeks are currently classified as unsafe for swimming or fishing.

Austin’s current water quality requirements reduce dirty runoff by requiring new developments to have onsite features that can filter pollutants out of runoff. For the past two decades, the city’s recommended water quality feature has been the sand filter. The problem is that sand, by itself, does an incomplete job of filtering out pollutants.

But if you add plants, you can filter out more, and this is what green stormwater infrastructure does. The most common GSI feature is the rain garden — a small basin lined with plants that can collect rain and let it soak into the ground. Another GSI feature, the green roof, catches rain so that it can later evaporate. Some GSI features don't use plants but can still cut runoff. Permeable pavement lets rain soak into the ground rather than run off. And a rain harvesting system can store rainwater for later onsite use. Right now the primary use is for landscape irrigation, but stored rainwater could also be used for building purposes such as flushing toilets.

Under the green stormwater infrastructure requirement in CodeNext, new developments will have to use features like these to meet their water quality standards. This change will be reinforced by two changes in the landscape section. Parking lots will have to be designed so that runoff can flow into adjacent landscaping, and developments with lots of impervious cover will have to use green stormwater infrastructure in a new program called Functional Green.

We believe that these proposals, while good, can still be improved. For example, we're disappointed that the beneficial use of stormwater provision in drafts 1 and 2 was dropped from draft 3. This regulation would have built on the new GSI regulations by requiring developments to retain and reuse a minimum amount of stormwater.

But overall, Environment Texas strongly supports the new stormwater proposals in CodeNext. Austin’s City Council has endorsed many of these ideas over the years, most recently with the green infrastructure resolution that it unanimously passed last year. While these policies aren’t unusual or novel, ours will be the first city in Texas to adopt anything like them. Austin has long set an example for the rest of the state in how to protect the environment. We can continue this leadership by adopting the new stormwater rules in CodeNext.