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Protected: ConV2 – Other Considerations

Every project is different and unique site circumstances may require additional planning or support.

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Erosivity Waiver

To obtain an Erosivity Waiver from the CSGP:

  • The site will result in the disturbance of fewer than five (5) acres and the site is not a portion of a common plan of development or sale that will disturb five (5) acres or greater. 
  • Calculate rainfall erosivity factor (“R” Factor) of less than five (5) during the period of construction activity for the region the project is in. 

This waiver is not available for projects declared significant contributors of pollutants or for any size construction activity that could reasonably expect to cause a violation of any water quality standard.

In-water Work

Construction projects often encounter activity that requires in-water or near-water work such as bridges, dams, wetland walkways, boat ramps, piers, or other activities that require a 401 Water Quality Certification. These are often required for projects that anticipate that the activity will create some level of turbidity in the receiving water and allowances need to be made to do the work with special considerations for how to control the effects of that work on the receiving water.

Small Projects and Road Maintenance

Projects less than an acre will likely require permitting and oversight by local jurisdictions. Local agencies and municipalities also conduct road maintenance projects that require the use of BMPs. Road maintenance BMPs are identified in the WSDOT RRMP bmp guide.

Contaminated Projects

Projects with soil and groundwater contamination require more upfront planning and management/treatment BMPs to be installed. There are several considerations for contaminated projects and Ecology has created guidance to help navigate these types of projects.

*If you have further questions regarding a contaminated project contact the Department of Ecology.

Chemical Treatment

In several cases, water quality standards may be very low and difficult to achieve, a project may want to remain active through the winter, the site needs to do some dewatering or the site may be contaminated. In these cases, projects may need to look into advanced treatment technologies, including chemical treatment to meet project outcomes. These technologies require a Request for Chemical Treatment form to be applied.

In addition, it is required when applying a chemical treatment to stormwater that it be done by a certified technician. Treatment technician certification information is available on the Ecology website.

Integration of LID

A significant aspect of any construction project is to make sure that the post-construction stormwater infrastructure is fully operational at the end of the project. The incorporation of LID (low-impact development) or green infrastructure is becoming more commonplace on projects. It is critical to consider how to protect that infrastructure (element 13 of the SWPPP) during construction.

Learn More About LID