SWPPP Permit Updates: What Washington Industrial Facilities Need to Know

Author: Ada H. Banasik, PE Published: January 2, 2020

Are you an industrial stormwater permit holder?

Your permit renews on January 1, and Stormwater Pollution Prevention Plan (SWPPP) updates reflecting the new permit are due January 30. We know these changes can be confusing, so we have provided a quick summary of the permit changes that apply to everyone:

The Standard Industrial Classification (SIC) code(s) must be replaced with a North American Industry Classification System (NAICS) code(s)

  • As a reminder, you had to enter a NAICS code in the Notice of Intent (NOI) that you filed electronically before the July deadline.

The new permit requires sampling following the first storm after September 1 (instead of October 1).

  • This means the monitoring section of the SWPPP must be updated.
  • We recommend sampling a summer storm (July or August) in case September is dry (during business hours). As a result, you may end up with two samples collected during the 3rd quarter. If you collect a second sample in September, the results will be averaged.

If you have achieved consistent benchmark attainment, you will now be required to sample at least once per year in the 4th quarter (rather than ceasing to sample for three years).

  • If a benchmark is exceeded in the 4th quarter sample, the consistent attainment “count” resets. You will need 8 consecutive quarters of sampling results below the permit benchmark to reach consistent attainment again.
  • However, you can collect more than one sample in the 4th quarter and use the average to determine whether consistent attainment still applies. We highly recommend sampling early in the quarter to leave time for additional sampling, if needed.

Infiltration systems must be shown as discharge points (to groundwater) on your SWPPP Site Map, but they do not require sampling (unless Ecology requests sampling, which has always been the case).

If you need help maintaining compliance with the SWPPP updates, please reach out to us. If MFA is already under contract to update your SWPPP, we have you covered and will be in touch in early January! 

Contact Us

Ada H. Banasik, PE

Principal Engineer

(503) 501-5222