10 Mar Greeening Stormwater Management in Austin – If not now, when?

Austin is currently bucking a trend. It is becoming increasingly well understood that the impact of development on water resources can be minimized by centering stormwater quality and quantity management on the use of distributed “green infrastructure” (GI), following the Low-Impact Development (LID) strategy. An example of where that has been codified is Montgomery County, Maryland. Their ordinance directs the use of “environmental site design” (ESD), defined as, “Using small-scale stormwater management practices, structural techniques, and better site planning to mimic natural hydrologic runoff characteristics and minimize the impact of development on water resources.” In the formulation and implementation of a stormwater management program for a development project, the ordinance directs that “An applicant must demonstrate that environmental site design has been implemented to the maximum extent practical before a structural best management practice is included in a stormwater management plan.” This is, of course, an embodiment of the LID strategy, in particular with a focus on distributed GI. The ordinance and its associated “Design Manual” – their local equivalent of Austin’s Environmental Criteria Manual (ECM) and Drainage Criteria Manual (DCM) – also effectively defines ESD as embodying volume-based hydrology (VBH), that mimicking of natural hydrological runoff characteristics, which it has been shown can indeed minimize the impact of development on water resources.

A couple years ago, after reviewing this ordinance and Design Manual in considerable detail, I suggested to Austin’s stormwater management bureaucracy that we might style a local version of ESD as “hydrologically sustainable site design” (HSSD), to put a focus on the bottom line aim of sustainable site design, and that we move to establish the primacy of this approach over the prevailing “end-of-pipe” approach. Current thinking in this field is that end-of-pipe management – which prioritizes those “structural best management practices” appended onto, instead of designed into, the project – is not producing hydrologically sustainable results. Indeed, when introducing the currently on-going Watershed Protection Ordinance (WPO) revision process, the city emphasized that it was breaking the bank trying to mitigate the downstream impacts of having failed to attain those results at the site level. You can see that in creek bank armoring projects all over Austin.

The city is now conducting “Phase 2” of the WPO revision process, which includes consideration of LID/GI/VBH strategies. Scanning what the city has posed for consideration of such matters, they appear to be simply looking at various methods, in isolation rather than as a part of a unified design process/strategy. There appears to be no consideration of the fundamental change in site design practice that is now understood to be necessary to produce those hydrologically sustainable results. If a designer were to focus on the LID/GI/VBH practices that might be brought to a state of legality here as a result of the “Phase 2” activities, that could indeed move us well forward toward attaining those results. But there appears to be no consideration of prioritizing those practices, of indeed requiring that an applicant must demonstrate that HSSD has been implemented to the maximum extent practical before an end-of-pipe structural best management practice may be included in a stormwater management plan. This follows on from the 2012 ECM revisions in which there was a nod toward what might be loosely understood as distributed GI, but it was presented as merely an option, not at all as an imperative.

This appears to be a matter of the “corporate culture” within the city regulatory machinery. One staff member, who is one of the principal drivers in the WPO revision process, once stated, “We cannot require LID.” I find this to be a surprising pronouncement, since the city has in effect been enforcing end-of-pipe management – and in many ways retarding LID/GI/VBH – for many, many years, and other than the intermittent legislative attacks on the city's authority to enforce environmental regulations generally, I am not aware that anyone has ever suggested that the city cannot do that. It would seem that the city's aim, and prerogative, should be to enforce the use of methods that would produce the most beneficial, the most sustainable results on the ground. Therefore, it would seem it indeed does have the ability – indeed the duty? – to write rules that would require that an applicant must demonstrate that HSSD has been implemented to the maximum extent practical before an end-of-pipe structural best management practice may be included in a stormwater management plan. So it would appear that the city not moving in that direction is a choice, not something they are barred from doing.

As noted, there is indeed an impetus for such a move. The Montgomery County ordinance is an exemplar of the direction the field is focusing all over the country. In the slide that was displayed at the last WPO stakeholder meeting were listed stormwater quality and quantity impacts to be blunted by how sites are designed, including:

• Increased runoff volume

• Increased peak discharge

• Diminished baseflow in creeks

• Stream channel enlargement [requiring all those armoring projects to protect creekside property]

• Decline in stream habitat quality

• Increased stream temperature

The next bullet on the slide was “And the list goes on”, a clear statement that there are a host of ills that we need to figure out how to blunt. It has become well understood that the LID/GI/VBH strategy would most effectively – and typically most cost efficiently – attain all that. These methods would also best attain at least 3 of the 6 dictates from City Council in the resolution that created the WPO revision process. So it would seem that it is a reasonable step to simply require that these methods be maximized before the prevailing end-of-pipe structural best management practices may be considered.

Yes, this will entail a bit of work to establish the details of what “maximized” practically means under local soil and climatic conditions, and to establish the specific measures of performance, with the perceived workload perhaps not being something the city is willing to take on. And yes we face inertia in both the regulatory and design communities. But …

For those who believe that such a fundamental change in practice is in the public interest, it is likely that “Phase 2” is our one and only opportunity to move regulatory requirements in that direction, so moving design practice in that direction, that we will have for a long time to come. So if not now, when? Is there any interest in pressing for consideration of this missing element of the “Phase 2” process? Thoughts on how we might proceed to do so?