A Nature-based Solution in an Urban Environment: The Case of Pillot Gully
Ken Lai
SWCA Environmental Consultants
Houston, TX
Jonathan Holley
Harris County Flood Control District
Houston, TX
Pillot Gully, situated in Northwest Houston, was a major maintenance and restoration project undertaken by Harris County Flood Control District (HCFCD), RPS Klotz Associates, and SWCA to address a concrete spillway failure that resulted in severe lateral and vertical instability, threatening nearby infrastructure. Located within a heavily urbanized watershed, SWCA was tasked with the engineering design of 2,400 feet of the channel using Natural Stable Channel Design (NSCD) techniques to restore channel capacity. The primary goal of the chosen channel restoration alternative was to create a stable channel within the existing HCFCD Right-of-Way using NSCD methods, protect infrastructure in the vicinity, and maintain flood control channel conveyance with a no-rise in FEMA Base Flood Elevation. Secondary goals included enhancing the natural aesthetics for trail users in the adjacent park and improving aquatic and ecological function.
The project was successfully completed in 2021 and featured various NSCD techniques. These techniques included the creation of a nested multi-stage channel, the development of a geomorphic floodplain within the larger flood control channel, the implementation of 18 boulder-constructed riffles, the use of toe-wood and natural sill logs for geomorphic floodplain stability, and the replanting of nearly 1,000 native trees.
This presentation will discuss HCFCD’s approach to utilizing nature-based solutions for stream and floodway management, as well as addressing the challenges faced, lessons learned, and the broader implications of creating resilient infrastructure using nature-based approaches in an urban environment.
About Ken Lai
Ken serves as a restoration engineer at SWCA. He has over 7 years of experience in hydraulic modeling, stream restoration design, and fluvial geomorphology. Currently residing in Colorado, he has been involved in all stages of a stream design project ranging from initial assessment, design, plan production, to construction oversight throughout the country. When not at work, you can find him up in the mountains hiking, camping, and fly-fishing.
https://www.linkedin.com/in/kennardlai/
About Jonathan Holley
Jonathan W. Holley has worked at the Harris County Flood Control District since 2009 in several positions related to stormwater quality and environmental regulatory compliance. Project planning and management experience includes enhancing regional stormwater detention basins with stormwater quality treatment wetlands, incorporating natural stable channel design features into channel improvement projects, tracking permit compliance, and performing water quality monitoring. His current responsibilities include managing the District’s environmental services and mitigation banking programs. He has a B.S. in Biology from Wake Forest University and a M.S. in Biology from the College of William & Mary. He is a Certified Professional in Erosion and Sediment Control (CPESC) and a Certified Professional in Stormwater Quality (CPSWQ)