Erosion Control Design
Introduction
Controlling erosion and keeping stormwater clean is a primary function of highway planting. Landscape architects work with the Project Development Team (PDT) to develop strategies to implement permanent and temporary erosion control treatments into all construction projects. The Caltrans Erosion Control Toolbox, which is located at the bottom of this webpage, provides guidance on selecting from a wide range of permanent erosion control treatments. It also serves as a valuable reference for erosion control best management practices and standards.
What is the Goal?
When selecting and combining various erosion control treatments, it is important, foremost, to clearly identify "success." Success is dependent upon site specific conditions, however, a successful erosion control treatment will sustainability address three specific areas - soils, water, and vegetation.
The goal of effective erosion control is twofold:
- Maintain water quality - Retain soils in place
- Increase infiltration - Reduce stormwater runoff
In the natural environment, these goals are fulfilled by vegetation, mulch/duff and porous soils. Vegetation protects the soil from raindrop impact and surface erosion. Healthy, porous soils infiltrate stormwater, reduce runoff, and retain water necessary to sustain healthy vegetation. The mulch/duff layer protects the soil surface from erosion, provides nutrients to sustain vegetation, and feeds microorganisms that contribute to a well draining soil structure.
Erosion Control Techniques
Permanent erosion control techniques remain in place after completion of construction and are used to provide long-term soil stabilization for disturbed areas caused by grading operations, slope failure repairs, stream bank rehabilitation, or wildfires and function to improve stormwater quality in compliance with the National Pollutant Discharge Elimination System (NPDES) permit.
Erosion Control Toolbox
The Caltrans Erosion Control Toolbox provides guidance on selecting from a wide range of permanent erosion control treatments, including:
- Compost incorporated into the topsoil to improve infiltration, increase water holding capacity, improve soil health, and increase rooting depth for plants.
- Collecting duff and re-spreading it following grading activities to add microbes, organic matter, nutrients and water storage capacity to the soil.
- Stepping slopes to reduce slope steepness, reduce stormwater runoff volume and velocity, increase infiltration, trap sediment, and create a niche for seed retention and plant establishment.
- Placing mulch or compost blankets to reduce raindrop erosion, improve infiltration, conserve soil moisture, provide nutrients, reduce runoff and the transport of sediment, reduce competition from invasive annual weed species and improve the potential for vigorous long term vegetation coverage.
- Using biofiltration strips and swales to filter pollutants from stormwater and reduce runoff.
- Planting trees, shrubs, and ground covers or brush layering to reduce raindrop erosion and hold soil in place.
- Seeding with deep-rooting California native grasses, wildflowers and perennials to reduce raindrop erosion and hold soil in place.
- Placing fiber rolls and compost socks to shorten slope length, intercept runoff, reduce runoff velocity, and remove sediment.
- Placing rolled erosion control products such as straw blankets, jute mesh, or coir (coconut) netting to provide immediate protection from surface erosion, retain soil moisture, and improve seed germination and vegetation establishment.