Silt control — also called sediment control — is the set of practices used to prevent silt and sediment from leaving a construction site and entering stormwater drainage systems, waterways, and sensitive ecosystems. It is not optional on most projects: federal and state regulations mandate silt control as part of a Stormwater Pollution Prevention Plan (SWPPP) for any project that disturbs one acre or more of land.

This guide covers the regulatory context, the available BMP categories, and how compost filter socks fit into an effective silt control strategy.

What Is Silt Control?

Silt is fine-grained soil material — particles smaller than sand — that is easily detached and transported by stormwater runoff. During construction, grading and earthwork expose bare soil that generates large volumes of silt during rain events. Without control measures, that silt:

• Enters storm drains and clogs municipal drainage systems
• Reaches streams, rivers, and wetlands, degrading water quality and harming aquatic habitat
• Carries attached pollutants (nutrients, metals, petroleum compounds) that are regulated under Clean Water Act stormwater general permits
• Creates off-site deposition that requires costly cleanup and creates legal liability

Silt control practices intercept sediment-laden runoff before it leaves the site and either filter it in place or settle it in a controlled location.

Regulatory Requirements

The regulatory framework for silt control on construction sites in the United States includes:

• EPA Construction General Permit (CGP): Applies to sites disturbing one acre or more. Requires a SWPPP with site-specific BMPs, regular inspections, and corrective action protocols.
• State stormwater permits: Most states administer their own construction stormwater permit programs under NPDES. Requirements vary by state and are generally equivalent to or more stringent than the federal CGP.
• Local requirements: Many municipalities have additional erosion and silt control requirements beyond the state permit.

Non-compliance can result in stop-work orders, fines, and liability for downstream damage. The cost of proper BMPs is almost always less than the cost of enforcement action.

Types of Silt Control BMPs

A complete silt control plan typically layers multiple BMPs to address the different sediment pathways on a site. Perimeter control alone is insufficient; inlet protection, slope stabilization, and check dams work together as a system.

Silt Socks in a Silt Control Plan

Compost filter socks like Filtrexx SiltSoxx are three-dimensional tubular mesh devices filled with filter media, and they can serve several BMP functions in a single plan:

• Perimeter control: An alternative to silt fence with a 50% greater flow-through rate and no trenching required
• Inlet protection: Positioned around storm drain inlets for immediate protection with easy repositioning
• Check dams: Installed across ditches and swales, with diameter selected to suit the channel
• Slope interruption: Installed in horizontal rows on graded slopes to interrupt sheet flow

Using one product type across multiple BMP applications reduces procurement complexity and training requirements. A crew familiar with silt sock installation can execute all four applications, and the socks install roughly three times faster than silt fence because there is no trench to dig. They can also be installed in freezing temperatures, which matters on winter schedules where trenching is impractical.

Inspection and Maintenance

All silt control BMPs require ongoing inspection and maintenance to remain effective throughout the project. Under the federal CGP, the standard schedule offers a choice of two routines, and you document which one you are following in the SWPPP:

• At least once every 7 calendar days; or
• Once every 14 calendar days and within 24 hours of a storm event producing 0.25 inches or more of rain in a 24-hour period (or a snowmelt discharge from a storm producing 3.25 inches or more of snow)

Sites discharging to sediment- or nutrient-impaired waters, or to waters designated Tier 2, Tier 2.5, or Tier 3, are subject to an increased frequency: every 7 calendar days and within 24 hours of a qualifying storm event. Reduced frequencies are available in defined circumstances, such as after temporary stabilization or during frozen conditions, and these vary by state.

Alongside the inspection schedule:

• Remove accumulated sediment from silt socks per the manufacturer's guidance and your permit's maintenance trigger
• Repair or replace any displaced, torn, or non-functional BMPs promptly
• Document all inspections and corrective actions in the SWPPP log

Because compost filter socks stay in place through storms and require less maintenance over time than silt fence, they generate fewer repair triggers between inspections — which reduces maintenance labour across the life of a project and helps crews keep sites compliant.