Working With Nature

About the author:

Matt Welch, CPESC, CESSWI, is technical & business development manager, and Adam Dibble, CPESC-IT, CESSWI, is senior marketing & erosion control brand manager for Profile Products LLC. Welch can be reached at [email protected], and Dibble can be reached at [email protected].

Matt Welch & Adam Dibble

In 2016, heavy rains ripped out erosion control blankets and left a creek bed severely eroded at a development site in Texas. The U.S. Army Corps of Engineers (USACE), Texas Commission on Environmental Quality (TCEQ), local Municipal Utility District and developer KB Homes all had ideas on how to remediate the failed site. Many of the proposed solutions, while viable, focused on taming Mother Nature, rather than working with her to prevent future issues.

Instead, the team selected a solution that allowed the site to return to more natural conditions. Stuckey’s Contract Services LP partnered with Profile Products to employ a green alternative to hard armor that offers a means of protecting high-discharge waterways and steep slopes. This solution allowed nature to punch through the creek at the levy break and reinforced the drainage path for inevitable heavy rain events.

Winning Over Mother Nature

Conroe, Texas, a suburb of Houston, is nestled on a floodplain in a wetland forest preserve. From 2015 to 2016, the U.S. Census Bureau named Conroe the fastest-growing city in the U.S., expanding from 76,000 to 82,000 people in only one year—a 7.8% growth, nearly 11 times higher than the national average. This influx of people brought a flurry of construction to the temperamental ecosystem.

Conroe is prone to flooding if rainfall exceeds more than 9 in. in 48 hours. According to a 2008 flood insurance study by Montgomery County, Conroe has a 10% chance of receiving that much rainfall in any given year, but urban development is exacerbating that risk. A study by Texas A&M University found the entire Houston area lost nearly 30% of its wetlands from 1992 to 2010—land that at one time could detain more than 4 billion gal of storm water. When Montgomery County experienced three consecutive 500-year floods from 2015 to 2017, the increase in impervious surfaces made the flooding even worse.

In April 2016, more than 12 in. of rain fell in the Conroe area. In May, another 11 in. fell. It was one of the wettest springs on record for the Houston area. At the time, KB Homes was working on the Cayden Creek subdivision. As the name implies, the subdivision has a small creek running through it; this creek eventually meets up with the San Jacinto River. As development of the subdivision began to increase, so did the amount of water that was being diverted into the creek.

In an attempt to stabilize the site and decrease runoff, contractors worked on vegetating 11 acres of the site with erosion control blankets for more than a year. Despite several attempts, they could not get vegetation to properly establish on more than two-thirds of the site, allowing sediment and runoff to flow into the creek.

When the spring storms hit, the strong water flow and lack of vegetation was too much for the creek to handle. The velocity of the water and the swirling action it created ripped out the blankets, washed away soil and blew out a 30-ft embankment on the creek. The resulting overflow moved into the amenity ponds and the channel. Sedimentation in the channel led to aggradation and decreased capacity, ultimately exposing the channel to a higher risk of flooding. 

Leaders on the development site weighed their options. 

“All the time, engineers are out here trying to reign in Mother Nature, and we usually never win—Mother Nature is going to win,” said Matthew Skinner, market development manager for Profile Products. “I like this idea of trying to work with nature.”

Realizing that rebuilding the crumbled section of the creek would only lead to a failure in another spot, project leaders chose to reinforce the eroded bank, let the water flow at the break point into the creek, divert the water to a retention pond and then allow it to flow back into the creek downstream.

Using this plan, workers tried to reinforce the new break point with riprap and erosion control blankets. However, the concentrated flow during storm events was too strong. The flowing water easily pushed the large rocks out of the way and deposited them more than 100 yards downstream. 

After that initial failure, the project consultants contacted Stuckey's Contractor Services LP, which partnered with Profile Products to create a solution that would establish sustainable vegetation and prevent erosion. The developers asked for results that would be stronger than the previously specified riprap and meet the standards of KB Homes, USACE and TCEQ. Each had its own requirements and guidelines that had to be met.

USACE proposed pouring concrete in the area to bypass the eroded bank and create a pathway for storm water. While concrete could have satisfactorily completed the job, it was not the green solution the team was looking for and would have been expensive to construct. KB Homes was over budget and needed an affordable, aesthetically pleasing solution that would solve its troubles and satisfy its homeowners. In addition, TCEQ examined the project from an environmental standpoint.