[This is an article I wrote on Linkedin back in 2016.  I’m reposting it again here now because, first, the City of Houston has a task force working on rule updates related to detention required in redevelopment projects, fill placement outside of the regulatory floodplain, and protection of the drainage right of way; and, second, Harris County has a task force working on updating their green infrastructure design requirements.]

The Houston-Galveston Area Council (H-GAC) hosted a May 20, 2016 workshop on the use of natural drainage systems in land development projects. The event was part of H-GAC’s rollout of it’s new Designing for Impact: A Regional Guide to Low Impact Development.

Low impact development (LID) – also called “green infrastructure” or “natural drainage systems” — is an approach to stormwater management and drainage design that uses natural systems to reduce the cost of drainage infrastructure, lower detention requirements, and create natural amenities in the properties it serves. The approach is called “low impact” development, because it reduces the volume and rate of stormwater runoff from most rain events, and thus reduces the rain’s impact on downstream properties.

Natural drainage subdivision concept rendering prepared by R. G. Miller Engineers, Inc. and Asakura Robinson.

I was asked to participate in the H-GAC workshop and to present a summary of incentives used by county and city land development permitting officials to promote the use of LID techniques in the Houston region. I initially agreed to present without giving the requested topic much thought, but as the event date approached, I started considering the content of my presentation.

I was shocked by a realization: There are no local incentives.

Sure, we have design criteria and guidelines for how LID must be implemented. We define how LID must be integrated into site designs in ways that also achieve our region’s serious and strict drainage and flood damage reduction rules for new development and redevelopment. We even have post-installation performance and acceptance testing for certain LID techniques. But our local authorities do not provide any credit, relief, or break from the current land development and permitting rules for the use of LID techniques.

Want proof? Check out these facts:

• Houston area land owners don’t get a discount on their stormwater drainage utility fee for using LID, as do land owners in Washington DC. Folks in our nation’s capital can earn a discount of up to 55% on their stormwater fee when they install LID features.
• Houston area land owners or operators are not eligible for grant funding to retrofit LID facilities on their properties, as are land owners in Philadelphia, PA. Folks in the City of Brotherly Love can obtain cash to retrofit LID facilities on their properties.
• Houston area land owners are not offered the discounted permitting fees or accelerated permitting timelines in exchange for the use of green building techniques that are available to developers in Sarasota County, FL.

So why should a Houston area land developer consider LID if there are no incentives?

• Reduced Detention Volume, Lower Cost, and More Developable Land: LID reduces the volume and speed of stormwater runoff from the development area. When this is demonstrated to Harris County and Harris County Flood Control District to using a drainage analysis, they will approve a lower detention rate, as long as the post-development peak flow is less than or equal to the pre-development peak flow. This is not available for projects that must be approved by the City of Houston. Less detention means more developable land, more lots, and a lower cost per lot for drainage infrastructure. We demonstrated a 45% drainage system cost reduction in a side by side comparison of traditional vs. LID drainage on 38-acre tract in northwest Harris County. Lot yield increased from 88 to 95, and every lot was next to a trail along a natural creek system.
• LID Costs are Reimbursable: LID drainage systems can be constructed using private developer financing. Once constructed, and after sufficient property tax revenues are realized, the water utility district served by the drainage facilities can sell tax-free municipal bonds and use the bond sale proceeds to reimburse the developer for the cost of the drainage system. This process is now fully authorized by the Texas Commission on Environmental Quality for those portions of the LID facilities that serve a drainage purpose.
• Reduced Imperviousness Equals Reduced Detention: The City of Houston determines detention requirements solely on the basis of impervious cover changes (pre-project vs. post-project). LID techniques such as permeable pavers, permeable asphalt, permeable concrete, or similar approaches can be used to reduce the magnitude of the impervious cover change. The graph below illustrates how the detention rate is reduced if the amount of new impervious area is restricted.

So there you have it. While it is true that Houston area land development authorities don’t currently offer any LID incentives, the current development rules, the cost structure of traditional drainage infrastructure, the space required for detention, lot yields, and changes in imperviousness frequently provide a compelling economic rationale for using these approaches.

PS: The locations that do offer incentives are under enforcement orders to mitigate overflows from combined sewer systems that carry wastewater and stormwater in the same pipes. Those communities have found that its much more cost-effective to reduce overflows by detaining, retaining, capturing, and otherwise managing rainfall using LID approaches in combination with grey infrastructure solutions than with grey solutions alone.