About Erosion and Sediment
Erosion occurs when vegetation or other soil cover is removed during ground-disturbing activities, exposing soil to wind and rain. The resulting sediment can be transported off site by wind, rain, and mechanical transfer from wheels and equipment. Pollutants such as oils, solvents, and heavy metals can stick to the sediment. Eventually, they settle out and accumulate in streets, the sewer system, and surface waters such as rivers and streams. Pollutants from eroded soil can harm fish and other aquatic life. Sediment can clog the sewer system, causing localized flooding or other costly damage.
The City's Role
The federal Clean Water Act requires cities to set rules and regulations to protect the city's sewer and stormwater systems and its watersheds. Environmental Services works with business and industry to meet these requirements.
Rules and Regulations
Portland City Code 17.39 prohibits the discharge of sediment into the storm sewer. The discharge of sediment from the jobsite may result in investigations, issuance of penalties, and required corrective actions.
Portland City Code Title 10, Erosion and Sediment Control Regulations are requirements to control the off-site discharge of sediment and require appropriate controls at the source. Guidance on how to utilize, install, and maintain these Best Management Practices (BMPs) can be found in the Bureau of Development Services’ Erosion and Sediment Control Manual. If the project has an Erosion and Sediment Control Plan, as required by the Manual, it must be followed.
Prevent Pollution through Best Management Practices
Follow these BMPs to minimize stormwater pollution from erosion and sediment:
- Install all necessary BMPs prior to starting ground-disturbing activities.
- Plan your project so the soil is exposed for as little time and during the driest weather as possible.
- Install catch basin inserts in all catch basins and stormwater inlets that receive stormwater runoff from your site.
- Install sediment controls around the project perimeter. Install sediment controls around soil stockpiles. Common forms of perimeter and sediment controls include, but are not limited to, straw wattles, sediment fences, mulch berms, and sidewalk subgrade barriers.
- Divert stormwater around exposed soil by placing straw wattles, berms, swales, or other diversions upslope and in the path of stormwater flows.
- Provide cover for soil and gravel stockpiles.
- Provide temporary stabilization or daily cover to the exposed soil for areas that are not in use, at the end of each day, and before rain events. Common forms of temporary stabilization include, but are not limited to, plastic sheeting, straw mulch, and seeding.
- Evaluate where runoff from plastic sheeting and diverted water will go to avoid increasing flows and localized flooding.
- Do not place or store soil or construction materials, including supplies and equipment, in the right-of-way.
- Do not store soil where it will be transported off the site.
- Sweep up any sediment that is spilled in the right-of-way immediately. Remove the sediment and place it back on the site.
- Do not use water to wash sediment or equipment to catch basins, the right-of-way, or areas that will discharge off the site.
- Inspect BMPs regularly, including before and after rain events.
- Maintain BMPs as needed based on inspection findings and manufacturer instructions.
- Provide permanent stabilization upon project completion. Till the soil no less than six inches deep and then apply grass seed, ground cover plants, mulch, and other permanent stabilization measures as quickly as possible. When seeding, provide erosion control or a layer of mulch to protect soil and seeds until germination occurs.
Failure to implement applicable BMPs may result in the discharge of pollutants, which is a violation of Portland City Code. The City will issue enforcement action in the form of a civil penalty if pollutants are discharged from your site. Appropriate measures are required to prevent the discharge of pollutants.