The Channel Lining Challenge

Channels, drainage ditches, and vegetated waterways face a fundamental erosion challenge: during storm events, flow velocities can increase dramatically, generating hydraulic shear forces capable of stripping vegetation and destabilizing the channel bottom and banks. Without adequate protection, this leads to channel widening, bank failure, downstream sedimentation, and loss of hydraulic capacity.

Traditional solutions include rock riprap (hard armor) or biodegradable erosion control blankets. Riprap is effective but expensive, heavy to transport and install, environmentally disruptive, and aesthetically undesirable in many settings. Biodegradable blankets protect only during the establishment phase and provide no reinforcement once they decompose.

Pyramat 75 HPTRM bridges this gap — providing permanent, high-performance erosion protection while supporting the establishment and long-term reinforcement of native vegetation.

How Pyramat 75 Protects Channels

Pyramat 75 is a 3-D woven polypropylene High Performance Turf Reinforcement Mat (HPTRM) engineered specifically for applications where high hydraulic forces are present. Its protective mechanism works in two phases:

Immediate Protection

Once installed, Pyramat 75 immediately reduces hydraulic shear on the channel surface. The mat absorbs flow energy, reduces surface velocity, and holds seed and soil in place during the critical vegetation establishment period. This is particularly important in the first growing season when vegetation cover is sparse and the channel is most vulnerable.

Root-Mat Composite Reinforcement

As vegetation establishes, roots grow up through the 3-D matrix of the mat and physically interlock with the polypropylene fibers. This root-mat composite is significantly stronger than vegetation alone — capable of resisting hydraulic shear forces that would strip unprotected turf from the channel. Over the 75-year design life of the mat, this composite reinforcement continues to protect the channel regardless of plant turnover through natural succession.

Key Performance Characteristics

• 3-D woven polypropylene construction — locks in seed and soil
• Superior UV resistance — direct sunlight rated for 75 years
• High interlock capacity with both soil and root systems
• Enhances seedling emergence in exposed conditions
• EPA-recognized Best Management Practice (BMP)

Case Study: Woodley Channel, Los Angeles County

Why Pyramat 75 Was Chosen

• Cost: Pyramat 75 cost significantly less than rock riprap for the same linear footage of channel protection.
• Design life: The 75-year rated life meets long-term infrastructure planning requirements.
• Environmental performance: Native vegetation eliminates the thermal and water quality impacts associated with rock channel linings.
• Carbon footprint: Pyramat 75's carbon impact is 30 times lower than rock riprap, supporting county sustainability goals.
• Maintenance: A vegetated channel lining requires less long-term maintenance than periodic riprap repair and replacement.

Pyramat 75 vs. Rock Riprap

For many channel lining applications, Pyramat 75 HPTRM offers substantial advantages over rock riprap:

• Installation cost: Pyramat 75 is generally less expensive to procure and install than equivalent riprap coverage. Riprap requires heavy equipment for placement; Pyramat rolls are manageable with standard erosion control installation equipment.
• Environmental impact: Mining, hauling, and placing rock generates substantial greenhouse gas emissions. Pyramat 75's verified carbon footprint is 30 times lower than riprap alternatives.
• Water quality: Vegetation supported by Pyramat removes pollutants from waterways, reduces thermal pollution through channel shading, and supports natural filtration processes. Riprap provides none of these benefits.
• Aesthetics: Vegetated HPTRM channels integrate naturally into the surrounding landscape. Rock channels are visually disruptive in parks, natural areas, and developed environments.
• Design life: Pyramat 75 is rated for 75 years. Rock riprap degrades over time through particle displacement, undermining, and vegetative invasion, requiring periodic maintenance and replacement.

Sizing and Roll Selection for Channel Applications

Pyramat 75 is available in two roll widths, both 120 feet long:

• 8.5 feet x 120 feet — Suitable for narrow channels, side slopes, and situations with limited equipment access. Covers 1,020 sq ft per roll.
• 15 feet x 120 feet — Preferred for wide channels and high-velocity applications. Fewer seams improve hydraulic performance. Covers 1,800 sq ft per roll.

For channel lining, the 15-foot wide roll is generally preferred because seams represent the highest-risk points for hydraulic failure. Minimizing seams reduces installation time and improves long-term performance. Both widths are available in Tan and Green.

For detailed sizing guidance across all Pyramat grades, see our Pyramat TRM collection.

Shop Pyramat 75 for Channel Lining

Pyramat 75 — 15' x 120' (Wide Roll)

Preferred for channel lining. Fewer seams, better hydraulic performance. 75-year design life. Available Tan or Green. BABA compliant when requested.

Shop Pyramat 75 Wide Roll

Pyramat 75 — 8.5' x 120'

Standard width roll for narrower channels and side slopes. Same 75-year rated performance. Tan or Green. BABA compliant when requested.

Shop Pyramat 75 Standard Roll

View the full Pyramat TRM collection.