1. Background
Located about 40 miles north of Dallas,
Denton is a small Texas town with a pro-
gressive, environmentally minded govern-
ment. Denton’s proximity to the
Dallas/Fort Worth has made it a growing
area like so many cities in the western
United States. With this growth comes the
challenges of managing stormwater runoff
from developed areas and the impervious
surfaces that accompany them. In Denton
this problem presented itself during heavy
rainstorms that inundated existing
stormwater controls, flooding part of
Bonnie Brae street near Interstate 35 and
the University of North Texas.
Problem
Flooding onto a major thoroughfare is not
just an inconvenience, but a serious safety
concern that the city had to address. The
existing drainage channel along Bonnie
Brae street was being overwhelmed during
heavy storms, flooding onto the road, and
scouring a significant amount of sediment
from the channel. Officials understood that
reconstruction of the channel was neces-
sary to increase its capacity and reduce
flooding. But due to the high visibility of
the area, the city was interested in a type of
channel lining that would be aesthetically
pleasing while keeping soil erosion under
control. There were suggestions to use 24
inch (60 cm) rock riprap to protect the
channel, but this type of lining did not sat-
isfy the aesthetic desires of the city and it
was very costly.
Solution
North American Green distributor Lone
Star Products is based in the Dallas/Fort
Worth area and presented to the city of
CASE
STUDY
Volume 8
Number 3
November 2005
14649 Highway 41 North
Evansville, Indiana 47725
812-867-6632
1-800-772-2040
FAX 812-867-0247
www.nagreen.com
C350 Provides Channel
Stabilization in an Urban
Environment: Denton, Texas
FACTS
Phase 1: A cross sectional view shows the C350’s patented
construction. Until vegetation becomes established, the C350
provides the sole means of erosion control. The ECMDS analysis
shows C350 to be stable in this phase.
Early Phase 2: Grass begins to sprout through the C350 in about 4
weeks. The matting retains its coconut fiber mulch while grass grow-
ing up through the mat is reinforced by its permanent structure.
ECMDS safety factors increase as vegetation grows.

2. Denton with the option of using the C350 composite turf rein-
forcement mat (C-TRM) for channel protection. C350 was an
attractive option because it would provide a greater level of
erosion control performance and aesthetics while eliminating
the need for costly rock riprap. In early 2004, representatives at
Lone Star Products discussed the channel’s geometry and
expected discharge volume with project designers and entered
these parameters into North American Green’s Erosion Control
Materials Design Software (ECMDS). The channel module of
the ECMDS package utilizes well established calculations from
the Federal Highway Administration and the U.S. Department
of Agriculture to analyze the effectiveness of any North
American Green product and/or vegetation in controlling soil
erosion. The software is also capable of analyzing the stability
of rock riprap, which would have also worked for this channel
but at a much higher cost. Results from these analyses showed
the C350 C-TRM to be a stable solution for controlling soil ero-
sion in all three vegetative development phases: unvegetated,
partially vegetated, and fully vegetated under a discharge rate
of 1500 cubic feet per second (42 m3
/s)
City officials reviewed previous installations of C350 in Texas
as well as the independent performance testing North American Green has conducted. They learned that C350’s per-
formance comes from its patented construction, which includes three high strength nets—the middle of which is cor-
rugated—and a coconut fiber mulch. This configuration forms a permanent three-dimensional structure, giving C350
the density to control erosion in an unvegetated state. The strength and thickness of the permanent mat structure
encourages vegetation entanglement to effectively reinforce vegetation for permanent erosion protection. Testing has
shown the patented C350 to act as a barrier between the flowing water and soil to reduce velocity and allow for depo-
sition of suspended sediment onto the matting. A coconut fiber mulch is added to the C350’s permanent mat structure
to provide the immediate cover needed while vegetation is establishing, but also acts to retain moisture and regulate
temperature at the soil surface for faster seed germination.
Results
This project marked the first time the city of Denton had chosen to install a TRM in a drainage channel or any type
of area. So one week before the scheduled installation, Lone Star Products met with project officials to discuss prop-
er installation techniques and emphasize the importance of correct installation to the success of the project. To ease
installation, North American Green has introduced the DOT System™ which involves marking the appropriate sta-
ple patterns on the C350 using environmentally safe paint. The DOT System increases installation rates and ensures
proper matting installation for optimum performance. Installation of the C350 was completed in the summer of 2004.
During the next 6 months, the channel remained relatively wet which helped the vegetation grow very quickly and
densely. With this fully established stand of vegetation, the C350 is not visibly noticeable but remains as a reinforc-
ing structure to permanently control soil erosion. Several intense storms have tested the matting’s claimed perfor-
mance without any reported erosion or matting damage within the channel. All told, 15,000 yds2
(12,541 m2
) of C350
were installed, saving the City of Denton $525,000, a 78 % cost reduction compared to the installation of 24 inch rock
riprap. This project now stands as a testament to the performance, cost savings, and aesthetics of using North
American Green’s C350 reinforced vegetative lining in place of hard armor.
Phase 3: Dense vegetation has established in only 6 months
thanks to the coconut fiber mulch. C350’s 3-D mat structure will
remain to permanently reinforce vegetation to a level shown in
the ECMDS analysis