One of the largest concerns from land disruption due to construction is stormwater erosion. Sediment carries nutrients and pollutants that degrade water resources and harm aquatic wildlife. Both permanent and temporary erosion control Best Management Practices (BMPs) can significantly decrease the amount of sediment that is carried into lakes, streams and rivers by stormwater runoff. This helps lessen negative impacts to local water resources and natural areas.
Compost Blanket
ODOT Specification 00280.15(f)
Description:
A compost blanket is a layer of loose compost placed on top of the soil surface in disturbed areas to control erosion and retain sediment, resulting in reduced stormwater runoff and erosion.
Applications:
Compost is applied as a temporary or permanent control for the uses of:
- Slope stabilization
- Establishment of vegetation and long-term sustainability of treated area
- Reducing pollutants from entering waterways
- Reducing size of swales, ponds or other Low Impact Developments (LIDs)
Compost Blankets are a multifunctional, low cost, simple BMP. They are typically applied to hillsides, slopes, or other susceptible bare soil existing within watershed drainage areas, degraded areas, and before or after development or construction activities.
Compost blankets are used in place of sediment and erosion control tools such as mulch, netting, or chemical stabilization.
Blankets protect the soil by:
- Absorbing energy from raindrops, reducing splash erosion
- Reducing or dispersing sheet flow runoff preventing the formation of gullies
- Reducing the velocity of runoff flow
Application and Limitations
Compost blankets can be placed on most soil surfaces including flat, steep, rocky, frozen, or difficult terrain. They are most effective on slopes between 4:1 and 1:1, such as stream banks, road embankments, and construction sites, where sheet flow can occur. They are not designed for areas that receive concentrated or channelized flows.
If the slopes are steeper than 2:1, then a compost blanket may need to be used in conjunction with other BMP’s such as binding agents, compost socks, compost berms, or netting to divert or diffuse concentrated flows of stormwater.
Many studies conducted by a variety of universities and state DOT agencies have reported the effectiveness of compost blankets and shown that compost blankets used for stormwater management and erosion control are low impact, cost effective and perform efficiently when correctly installed. Material quality is of high importance. If quality is compromised, the benefits of it are, too.
Compost Filter Sock
ODOT QPL 4529
ODOT Specification 00280.15(f)
Sediment Barrier – Type 8
ODOT QPL 4529
ODOT Specification 00280.16(e)
Compost socks are contained compost filter berms; they are mesh tubes filled with compost and placed perpendicular to the direction of sheet flow to control erosion and retain sediment. The sock conforms to the surface of the ground and acts as a barrier that filters runoff as it passes through.
Compost Socks have more surface contact with the soil than traditional BMPs, so stormwater runoff is less likely to create channels or rills. The increased contact area paired with the weight of the sock allows the water to pool upgradient, allowing solids to settle out. They can replace traditional BMPs, such as silt fence or straw bale barriers, and are usually more effective.
Application and Limitations
Compost socks can be used on steep slopes with fast flows if they have close spacing or are used in conjunction with other BMPs. Compost socks can function as either a sediment barrier or as an inlet protection device.
Compost socks can be seeded to provide either a temporary or permanent vegetative cover, and they can be left in place as they are biodegradable.
Compost socks do not require any trenching, therefore they do not disturb the soil any further. The location should be prepared by removing all irregularities upon the surface that are larger than 3” prior to installation
Compost Berm
Sediment Barrier – Type 9
ODOT Specification 00280.15(f)
Application and Limitations
Compost berms can be used to prevent erosion by shortening the slope length and slowing runoff velocity which interrupts sheet and rill erosion. Compost berms can be used in the following applications:
- Along the perimeter of a construction site to prevent turbid water from leaving the project site
- At intervals along a steep slope to capture and treat sheet flow
- In combination with other BMPs, such as blankets, to slow the flow
Compost berms can be installed on any type of ground surface; however, the berm must come into direct contact with the surface to be effective. Compost berms may not be suitable in areas where large amounts of flow are expected, such as streams, ditches, or waterways. They are commonly seeded to provide temporary or permanent vegetative cover. Due to berms being biodegradable, they can be left in place or dispersed after use, negating the need for removal. They typically only function for one to two seasons.
