Silt Fences, Wattles, and Berms: Choosing the Right Barrier for Your Site

When setting up your construction site's perimeter controls, it is easy to assume that any physical barrier will do the job. Many contractors simply throw down whatever material is cheapest or most readily available. However, using the wrong Best Management Practice (BMP) for your specific terrain is a guaranteed way to fail an inspection—or worse, suffer a catastrophic blowout during a heavy storm.

Understanding the difference between silt fences, wattles, and berms is critical for effective Stormwater Pollution Prevention Plan (SWPPP) compliance. Here is a breakdown of when and how to use the "big three" perimeter controls.

1. Silt Fences: The Heavy-Duty Perimeter

A silt fence is a temporary barrier made of woven geotextile fabric stretched across wooden or metal posts. It is designed to pool runoff water, allowing sediment to settle to the bottom before the water slowly filters through the fabric.

• Best Used For: Large areas with a moderate slope where a high volume of sheet flow is expected. They are the gold standard for site perimeters.

• The Common Mistake: Silt fences must be trenched into the ground. If the bottom edge of the fabric is just pinned to the surface, water will easily flow underneath it, rendering it useless and triggering a violation.

2. Wattles (Fiber Rolls): The Flexible Check Dam

Wattles are long, tubular rolls filled with straw, flax, or coir (coconut fiber). They are highly flexible and conform easily to uneven terrain.

• Best Used For: Breaking up the flow of water on long slopes, protecting storm drain inlets, and wrapping around stockpiles. They act as small check dams that slow water down rather than holding back large pools.

• The Common Mistake: Wattles are fragile. If heavy machinery or delivery trucks drive over them, they rupture and fail instantly. They also need to be staked properly into a shallow trench to prevent undercutting.

3. Earthen Berms: Directing the Flow

An earthen berm is a compacted ridge of soil, often built using dirt already excavated from your job site.

• Best Used For: Diverting clean water away from disturbed areas or channeling dirty runoff toward a designated sediment basin. Berms are excellent for managing large volumes of fast-moving water.

• The Common Mistake: Because berms are made of dirt, they can become a source of sediment themselves if they aren't stabilized with vegetation, hydroseed, or erosion control blankets.

We Choose the Right Tool for the Job

You don’t have to guess which barrier your site needs. Accena’s certified experts map out your site's topography and specify exactly which BMPs will provide maximum protection at the lowest cost. Better yet, our field crews install them flawlessly—trenching fences, staking wattles, and securing your perimeter so you can build with confidence.

Need expert installation for your site's BMPs? Contact the Accena Storm Troopers today.