Erosion Control
Solutions

In California, erosion control BMPs (best management practices) are required on any project that disturbs soil and falls under a grading permit or the state's Construction General Permit. The Construction General Permit applies to projects disturbing 1 acre or more, requiring a SWPPP (Stormwater Pollution Prevention Plan) and active BMP implementation. Smaller graded projects under local county permits also typically require stormwater control measures as a permit condition. The practical answer: if you're moving earth, you need erosion control before the first rain — not after.

A SWPPP (Stormwater Pollution Prevention Plan) is a site-specific document required under California's Construction General Permit for projects disturbing 1 acre or more of soil. It identifies potential pollutant sources, maps drainage patterns, specifies which BMPs will be installed and where, and establishes an inspection and maintenance schedule. Projects under 1 acre don't require a formal SWPPP but do need to implement erosion and sediment controls under local county requirements. DW Excavation can assist with BMP installation that supports your SWPPP's requirements — we recommend coordinating with a qualified SWPPP preparer for the planning document itself.

These terms are related but distinct. Erosion control prevents soil from detaching and moving in the first place — through vegetation, mulch, matting, or physical covers that protect bare soil from rain impact and runoff. Sediment control captures soil that has already moved and prevents it from leaving the site — through silt fences, sediment basins, inlet protection, and biorolls. A complete erosion control program uses both: you protect the soil surface where you can, and you catch what escapes before it reaches a drain or waterway. Most regulatory requirements address both categories.

Initial germination typically occurs within 7–14 days under good conditions — adequate moisture, moderate temperatures, and appropriate seed mix selection for the site. Meaningful root establishment that provides erosion resistance usually takes 4–6 weeks. For this reason, hydroseeding works best when applied early enough in the season to allow establishment before heavy rain arrives. If you're close to the rainy season and don't have time for vegetation to establish, physical measures like matting or erosion control blankets should be used alongside or instead of seeding until roots can develop.

Yes — significantly so. Wildfire removes the vegetation and root structure that holds soil in place, and fire-burned soils often develop a hydrophobic layer that causes runoff rather than absorption. This makes burned slopes among the highest-risk erosion sites, particularly in the first one to two post-fire wet seasons. Treatment typically involves emergency stabilization measures immediately after fire (mulching, erosion control blankets), followed by hydroseeding and longer-term revegetation. In Sonoma County, where wildfire history includes major events across the wine country, we have direct experience with post-fire erosion control scoping and implementation.

Some measures can be installed in wet conditions — silt fencing, biorolls, and inlet protection don't require dry ground. Others, like hydroseeding and erosion control matting, work best on dry or damp (not saturated) soil. The key issue is that saturated clay soils in Sonoma County become unstable under equipment, and working in standing water creates its own compliance issues. Where possible, we strongly recommend getting measures in place before the wet season begins rather than trying to install them during active rain events. If a project is caught without protection when rain arrives, we prioritize the measures that can be safely deployed immediately.

Sediment discharge from a construction site to a storm drain, waterway, or adjacent property can trigger enforcement action from the Regional Water Quality Control Board, the county, or both. Depending on the discharge volume and receiving water sensitivity, penalties can be substantial — and you may be required to clean up deposited sediment at your own expense. More practically, it creates neighbor and liability issues that are far more disruptive than the cost of preventive measures. This is why proactive erosion control — not reactive cleanup — is always the right approach.

Contact us as early as possible — ideally by late summer or early fall for the upcoming wet season. We schedule erosion control work around active grading projects and can coordinate with your general contractor or project manager to ensure measures are in place at the right project phases. Call (707) 601-9091 or use the contact form on this page to discuss your project timeline.

Yes, when correctly specified and installed. Erosion control blankets and mats are designed for slope applications and are rated by slope steepness and expected rainfall intensity. Coconut fiber mats (coir) are commonly used on steeper slopes because they're dense enough to protect soil while allowing vegetation to establish through the mat. On very steep grades, additional anchoring and sometimes mechanical reinforcement is needed. The selection of matting type, anchor pattern, and whether to combine it with seeding or other measures depends on the specific slope and exposure — which we assess during a site visit.

We visit the site and evaluate slope angles, soil type, drainage patterns, proximity to storm drains or waterways, project phase and timing, and any specific permit conditions that apply. From that we develop a scope of erosion control measures appropriate for the site conditions and regulatory requirements. The assessment is the starting point for accurate pricing and scheduling — remote quoting from photos or parcel maps is possible for a rough estimate, but a site visit gives you a number you can rely on. Call (707) 601-9091 to schedule.