Erosion and Sediment Control Management in Construction
08/02/2022
Across Washington and Oregon, measures for erosion control are high priorities for local, state and federal governments. Construction sites over one-acre are required to inspect these measures through an individual known as a Certified Erosion and Sediment Control Lead (CESCL). Dictated by the Washington State Department of Ecology (DOE), as well as the Oregon Department of Environmental Quality (DEQ), stormwater inspections and sampling at construction sites are required to be completed and logged regularly.
In a previous post, we discussed dewatering, one of the many facets of erosion control and stormwater management that involves removing ground or surface water from a given location. The systems in place for the various dewatering methods must be monitored, tested and data logged by the onsite CESCL inspector to ensure that water is treated and redistributed correctly.
What is Erosion Control?
To define erosion control, we must first identify what erosion is. Erosion occurs naturally in the environment when materials such as soil, rocks and sediment are worn away and/or transported over time, typically by naturally occurring phenomenon such as wind, rain, or flowing water. Erosion can be sped up by human interactions, particularly during construction projects, logging, or clearing of vegetation for practices such as farming. Fast-paced soil erosion reduces the quality of soils and can transport debris, contaminants and pollutants into local waterways, streams and rivers. Additionally, soil erosion can lead to topsoil reduction and limit the land’s ability to produce crops.
Another common form of erosion is water erosion, such as during times of snowmelt, flash floods and large rainstorms. Large volumes of water runoff can decimate topsoil in fields, cause landslides and more. In construction, we work hard to control erosion as we disrupt the earth for new structures. The process of removing vegetation destabilizes soil in such a way that without erosion controls, sites can experience significant erosion and other complications that impact neighboring sites and waterways.
Erosion control is the method used to prevent soils and sediment from leaving the construction site. Methods of erosion control include man-made barriers and/or structures, land management techniques, plantings and dewatering strategies.
What Methods Help with Erosion Control?
To meet the DOE and DEQ standards, preventing the transfer of soils and sediments to neighboring properties during construction is critical. Site supervisors must prevent soil and sediment from leaving the site, and control water runoff to do so.
Some methods of preventing erosion include:
Vegetation
Plant vegetation on exposed soils helps develop roots to prevent soils from moving.
Plastic Sheeting
Install plastic sheeting on exposed soils to prevent water from accessing the surface and dislocating soils.
Matting
Use matting materials, such as woven or sandwich type fabrics, on top of soils to slow down the movement of soils if water or wind is present.
Sediment Fencing
Install sediment fencing, a barrier generally made of a plastic material, to stop material from flowing off the site.
Rough Seeding
Install grass seed on exposed soil to create a natural buffer from eroded materials once germinated.
In addition, controlling the flow of water onsite through proper dewatering methods is a crucial component of erosion control. Recent updates to the Erosion control requirements by DEQ and DOE have severely limited the amount and type of water that can leave a site, so proper onsite water management is crucial for a successful construction project.
What is Turbidity Monitoring?
Turbidity is “the measure of relative clarity of a liquid”. In other words, the turbidity of a liquid describes how clear or cloudy it is. Water with cloudiness, or high turbidity, can raise concerns about health, as the debris in the water can house diseases and, while not always the case, studies show strong links between the removal of high turbidity with lowering protozoa.
Runoff, whether upstream or downstream from a construction site, is a common problem for turbidity levels and must be tested to meet acceptable levels before being released offsite. The allowable turbidity of water runoff is equivalent to a 10% increase from the existing turbidity of the waterway that will intercept the runoff. Due to the ever-changing weather and environmental patterns in the northwest, turbidity tests must be completed often as the receiving waterway will have fluctuating turbidity levels. If turbidity is found to be too high, it’s critical to adjust erosion control measures until acceptable levels have been reached. The regulating erosion control party (DEQ or DOE) has the ability to shut down a construction project if the turbidity of water runoff is too high, so it is imperative to keep a close eye on all construction waters.
Onsite Erosion and Sediment Control Planning
Contractors preparing to work must have an approved Erosion and Sediment Control Plan approved by the appropriate state agencies prior to beginning construction. The State of Oregon requires a 1200C permit be in place, which includes the erosion control plans put in place for each specific site.
In addition, both Oregon and Washington require the presence of an individual who is a Certified Erosion and Sediment Control Lead, who will be responsible for stormwater inspections and sampling. These certifications, once achieved, are good for three years. The onsite CESCL is responsible for logging findings, updating plans for erosion and sediment control as the site is modified, and enforcing proper protocols as construction proceeds.
Approved Erosion and Sediment Control plans will include, at minimum, the following details:
- Existing site boundaries
- Building layout and site plan
- All site water discharge points and related protective methods
- Erosion control BMPs (best practice methods) including silt fencing installation, material berming, stray wattles, inlet protection, site entrance, etc.
- Any added or updated BMPs for site erosion control
The Approved Erosion Control and Sediment Plans are to be treated as a living document onsite. Depending on the jurisdiction, an updated plan must be submitted for formal approval each time an adjustment is made. Should a DEQ or DOE inspector visit your site, an up-to-date Approved Erosion and Sediment Control plan is required. If individual contractors do not have in-house CESCL experts, they can hire third-party companies to complete this service for them. General contractors or excavators often have in-house CESCL experts available, and the individual responsible for each site should be discussed ahead of mobilization.
Final Thoughts
Erosion and sediment control management is a complicated topic that, while simplified for the purposes of this article, requires diligence and planning to properly execute. It’s important that contractors review local, state and federal guidelines for stormwater management, erosion, and sediment control measures, as well as how to comply with each jurisdiction’s requirements. The consequences of failing to comply with these regulations can be severe, including fines, delays in permit issuance and more.
If you’re planning to pursue a large building project, talk with our teams about the best ways to ensure compliance with these regulations.