Skip to content

CSGP: Other Considerations

Looking to achieve compliance with the Washington State Construction Stormwater Permit can be a complex and challenging process. While there are basic requirements that must be met, there are additional factors that can impact compliance.

These factors can include site-specific issues, site history, and the use of best management practices. Understanding and addressing these additional considerations can help ensure successful compliance with the permit and protect Washington's water resources.

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

While projects less than an acre don’t require coverage under the CSGP, they 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 and the WSDOT RRMF 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

There are several scenarios that may make water quality standards difficult to achieve for a site.  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.

Applying chemical treatment to stormwater must be done by a certified technician. Treatment technician certification information is available on the Ecology website. To find approved chemistries visit the Ecology TAPE page and click the construction tab under ‘approved technologies’.

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