Choosing the Proper Erosion Control Blanket: Advanced Guide for Professionals
- paullindemulder
- 3 days ago
- 6 min read
Updated: 1 day ago
In our first blog, Choosing the Proper Erosion Control Blanket – A Guide , we covered the basics. This one goes a bit deeper for those who want more detail.
Erosion control isn’t one-size-fits-all, especially when you’re planning for complex projects near sensitive environments or under demanding conditions. This advanced guide* is built for professionals like RP.Bios, P.Bios, CPSCs, P.Engs, and Army Corps engineers who make critical decisions based on site-specific variables and technical performance. We’re going beyond the basics to talk data, design, and the real-world factors that separate a decent installation from a durable, high-performance one.
1. RUSLE Equation: The Starting Point
The Revised Universal Soil Loss Equation (RUSLE) is the foundational model for estimating soil erosion:
A = R × K × LS × C × P
Where:
A is average annual soil loss (tons/acre/year)
R is rainfall-runoff erosivity
K is soil erodibility
LS is slope length and steepness
C is cover-management (aka the C Factor)
P is support practices
Your erosion control blanket directly impacts the C factor. High-performance blankets—especially when used with appropriate vegetation—can reduce C by over 90%.
2. Tensile Strength: Holding Power Matters
Blankets need to handle more than just erosion. They must resist forces from installation, runoff, and occasional maintenance traffic. Tensile strength—typically measured in lbs/ft or kN/m—is a key spec. If it’s too low, the blanket can tear or shift under stress. Too high, and it may hinder vegetation growth or drive up costs unnecessarily.
Blanket Type | Typical Tensile Strength (MD) |
Bio Double Net Blanket (with 100% straw) | ≥ 75 lbs/ft |
Bio Double Net Blanket (with 100% coir) | ≥ 100 lbs/ft |
Standard Double Net Blanket (with 100% straw) | ~100-120 lbs/ft |
Standard Double Net Blanket (with 100% coir) | 150+ lbs/ft |
Match tensile strength to:
Site traffic during establishment
Stormwater load during heavy rain
Installation equipment and anchor spacing
3. Shear Stress: Water's Lateral Assault
Shear stress - measured in pounds per square foot (psf) or Pascals (Pa)—refers to the horizontal force that moving water applies to the soil surface. In channels, swales, and steep slopes, shear stress is often the primary cause of erosion control failure.
For example, a rolled erosion control blanket rated for 2.5 psf can resist 2.5 pounds of water force per square foot before soil begins to erode underneath.
If you're working near water bodies or on steep embankments, select a blanket tested for maximum shear resistance. Typical values include:
Double Net Straw Blankets (BMP-BDNS): ≥ 1.75 psf (≥ 84 Pa)
Double Net Coconut Blankets (BMP-BDNC): ≥ 2.25 psf (≥ 108 Pa)
Turf Reinforcement Mats (BMP-TRMP): Range from ≥ 6.0 psf (≥ 287 Pa) to ≥ 12.0 psf (≥ 575 Pa)
Tip: The closer your project is to concentrated flows (e.g., ditch bottoms, culverts, outfalls), the more critical shear resistance becomes.
4. C Factor: Cover Performance Defined
The C Factor quantifies a blanket’s effectiveness in reducing erosion relative to bare soil (which has a C factor of 1.0). It’s site-specific and influenced by soil type, slope, rainfall, and vegetation—but here’s a useful rule of thumb:
Lower is better.
Straw blankets: 0.20 - 0.10
Straw/coconut mix: 0.10 - 0.05
Coir blankets: 0.05 - 0.03
Synthetic TRMs: 0.01 or less
Pick based on slope, expected rainfall, and vegetation timing. If vegetation will take longer to establish, choose a higher coir content for extended protection. If growth is expected quickly, straw-heavy blankets usually provide enough short-term erosion control.
5. Slope Gradient: The Real Multiplier
Slope length and steepness significantly affect how a blanket performs.
Slope (H:V) | Recommended Blanket Type |
4:1 to 3:1 | Short-term Straw Blanket (either bio or standard) |
3:1 to 4:1 | Extended-term: Straw/Coconut Blend (either bio or standard) |
2:1 to 1.5:1 | Long-term: Coir Blanket (either bio or standard) |
1.5:1 to 1:1 | Permanent: TRM with Anchor Trenching |
Note: When slope ≥4:1 (25%), double-check with project-specific RUSLE calculations.
6. Longevity: How Long Does It Really Last?
When choosing the right Erosion Control Blanket (ECB), factors like project duration, climate, and expected vegetation growth are key. But one of the biggest drivers of longevity is the blanket’s fill material.
Straw is ideal for short-term stabilization, while coconut fiber offers extended protection for longer-term needs. Straw/coconut blends give you a balance of both — great for moderate timelines and variable site conditions.
Blanket Type | Expected Longevity |
Straw (bio or standard netting) | 6-12 months |
Straw/Coconut (bio or standard netting) | 12-24+ months |
Coir (bio or standard netting) | 24-36+ months |
TRM (synthetic turf reinforcement mat) | Permanent |
Note:
In dry/desert climates, degradation is slower.
In humid/tropical zones, organic fibers break down faster.
It’s good practice to note that these are typical ranges—site conditions and installation quality can shorten or extend real-world performance.
7. Environmental and Project Considerations
Water Proximity:
Near creeks, wetlands, or sensitive habitats, prioritize natural-fiber biodegradable blankets (like leno-woven jute, coir, or straw/coconut blends) to avoid introducing plastics into the ecosystem.
Leno-woven jute blankets are especially wildlife friendly due to their loose weave and natural materials.
Climate Zones:
Drier Climates: Choose slower-degrading fibers such as coir for longer-lasting protection.
Rainforest/Wetter Climates: Expect faster decomposition; consider synthetic or high-tensile coir blankets for durability.
Freeze-Thaw Zones: Use blankets that maintain strength through cycles—straw/coconut blends work well here.
Project Type:
Road Shoulders & High-Traffic Areas: Select blankets with higher tensile strength and durability to withstand vehicle splash, maintenance equipment, and occasional traffic.
8. Biodegradable (Jute Netting) vs Standard Blanket: A Side-by-Side
Feature | Bio Blanket | Standard Blanket |
Fiber | 100% natural (straw, coir, jute netting) | Synthetic nets + natural fill |
Degradable | Fully naturally biodegradable | Partially biodegradable |
Tensile Strength | Generally lower to similar (depends on fill type) | Similar |
Best For | Sensitive sites & wildlife-friendly areas | Cost considerations |
9. Pulling It All Together
Choosing the right blanket means balancing RUSLE factors with real-world demands:
Match tensile strength and shear stress specs to your site’s mechanical challenges.
Use the C factor to gauge erosion reduction potential.
Plan for the long haul — will the blanket last through vegetation establishment?
Don’t forget slope, rainfall, sensitive environments, and permit requirements.
Real-World Application: Selecting an Erosion Control Blanket Near a Fish-Bearing Watercourse*
Project: New access road construction on a hillside beside a salmon-bearing creek in British Columbia.
Site Conditions:
Soil Type: Silty loam, moderately erodible (K = 0.32)
Slope: 3:1 H:V (≈33.3% grade), 40 meters long (LS factor calculated at 3.9)
Rainfall: Average annual erosivity index (R) of 150
Vegetation Establishment: Expected to be slow due to late season planting and cooler temperatures
Environmental Concern: Proximity to fish-bearing stream requires maximum sediment control
Support Practices: Contour ditching installed (P factor = 1.0)
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Step 1: Calculate Soil Loss (A) Using RUSLE
A = R × K × LS × C × P
At this point, the engineer needs to estimate C (cover-management factor) for possible erosion control blankets.
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Step 2: Evaluate C Factor Options
Bare soil C = 1.0 (no blanket/worst case)
Biodegradable Straw Blanket (BMP-BDNS) C = 0.15
Biodegradable Straw Coconut Blanket (BMP-BDNSC) C = ~0.07
Biodegradable Coconut Blanket (BMP-BDNC) C = 0.032
Synthetic TRM C = 0.01
Since the vegetation will take longer to establish and the site is sensitive (near water), the engineer suspects that the straw-only option (BMP-BDNS) won’t last long enough to provide adequate protection.
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Step 3: Calculate Annual Soil Loss for Two Blanket Options
Option A: Biodegradable Straw Coconut Blanket (BMP-BDNSC, C = 0.07)
A = 150 × 0.32 × 2.0 × 0.07 × 1.0 = 6.72 tons/acre/year
Option B: Biodegradable Coconut Blanket (BMP-BDNC, C = 0.032)
A = 150 × 0.32 × 2.0 × 0.032 × 1.0 = 3.07 tons/acre/year
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Step 4: Consider Mechanical Specs & Environmental Needs
The engineer reviews erosion control blanket specs:
BMP-BDNC (Biodegradable Double Net Coconut Blanket):
Tensile strength: ≥ 100 lbs/ft (strong enough for slope)
Shear stress resistance: 2.50 psf (good for concentrated flows)
Longevity: 24-36+ months (matches slow vegetation growth)
100% biodegradable, wildlife-friendly netting (jute/coir)
C factor: ~0.032 (check ASTM D6459 or ASTM D7101)
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Step 5: Final Decision
Given the proximity to the fish-bearing creek, slow vegetation growth, and moderate slope (3:1), the engineer selects BMP-BDNC (Biodegradable Double Net Coconut Blanket) for its superior durability, erosion reduction, and environmental friendliness.
Without any blanket, the estimated annual soil loss would be:
A = 150 × 0.32 × 2.0 × 1.0 × 1.0 = 96 tons/acre/year
With BMP-BDNC, the expected soil loss drops to:
A = 150 × 0.32 × 2.0 × 0.032 × 1.0 = 3.07 tons/acre/year
Calculated Results: This means the selected blanket would reduce erosion by approximately 97%, preventing over 93 tons of sediment per acre from entering the nearby salmon-bearing creek — a critical improvement for water quality and habitat protection.
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Summary:
By combining site-specific data with RUSLE calculations and blanket specs, the engineer confidently selects a BMP-Biodegradable Double Net Coconut (BMP-BDNC) to meet both performance and environmental goals.
Looking for Technical Sheet or CAD file? Click Here
Have questions about a specific site or Erosion Control Blanket? We can help you spec the right blanket, matched with detailed erosion calculations and specification/data sheets.
Disclaimer: This guide is provided for general informational purposes only and does not constitute professional advice or a guarantee of performance. BMP Supplies makes no representations or warranties, express or implied, regarding the suitability, effectiveness, or results of any product or recommendation contained herein. Site conditions, environmental factors, and project requirements vary widely. It is the sole responsibility of the qualified professional to assess all relevant factors and determine the appropriate product and installation method for each specific application. BMP Supplies assumes no liability for any use or misuse of this information.
