Source Control and Stormwater at Sediment Sites

1. Source Control and Stormwater at Sediment Sites Warren Hansen, PE Windward Environmental LLC

2. Challenges and complexities of controlling stormwater sources Thinking in thecontext of SCALE

3. Stormwater and other pathways

4. Stormwater as One of Several Pathways

5. Sources impacting facility sediment:before and after site-wide remediationHypothetical example: Local sediment quality dominated by adjacent or upstream in-water sediment Local sediment quality more dominated by nearby pathways/sources

6. Sources at the facility level

7. Questions at the Facility Level • What’s the relative role of stormwater vs. other sources? • Have contaminant sources been identified? • Are conveyance systems understood? • When are stormwater controls necessary? • What are the control objectives? • What are the control options? • How is effectiveness measured?

8. Stormwater Conveyances

9. Aboveground Sources Run-on from neighboring properties Industrial/ commercial activities Atmospheric deposition Structural sources

10. Atmospheric deposition King County. 2008. Lower Duwamish Waterway Source Control Project: Passive atmospheric deposition sampling, Lower Duwamish Waterway: Monitoring report - October 2005 to April 2007. King County Department of Natural Resources and Parks, Seattle, WA. Averages calculated using detected concentrations from only the South Park Community Center station.

11. Aboveground Sources Run-on from neighboring properties Industrial/ commercial activities Atmospheric deposition Structural sources

12. Subsurface infrastructure - Infiltration and entrainment (aboveground sources)

13. Interceptors, Outfalls, and Receiving Waters

14. Interceptors, Outfalls, and Receiving Waters LATERALS ft INTERCEPTOR ft Outfall High water level in river or bay

15. Stormwater conveyances Additional factors to consider • Age • Design (depth, routing, etc.) • Material(s) of construction • Mode of construction • Remnant “on-site” combined systems (older facilities)

16. When are stormwater controls necessary? What are the objectives?

17. Requirements for Stormwater Treatment Clean Water Act (NPDES) Municipal Codes Potential Superfund Site Involvement

18. General Industrial Stormwater Permit Level Three Corrective Actions – Treatment BMPs Permittees that exceed an applicable benchmark value (for a single parameter) for any three quarters during a calendar year shall complete a Level 3 Corrective Action in accordance with the following: Review the SWPPP and ensure that it fully complies with Permit Condition S3. Make appropriate revisions to the SWPPP to include additional Treatment BMPs with the goal of achieving the applicable benchmark value(s) in future discharges. The Permittee shall Use Treatment BMPs consistent with the Stormwater Management Manuals for Western or Eastern Washington

19. General Industrial Stormwater Permit Recently revised permit references Sediment Management Standards: • S10.A: Discharges shall not cause or contribute to a violation of Surface Water Quality Standards (Chapter 173-201A WAC), Ground Water Quality Standards (Chapter 173-200 WAC), Sediment Management Standards (Chapter 173-204 WAC), and human health-based criteria in the National Toxics Rule (40 CFR 131.36). Discharges that are not in compliance with these standards are prohibited. • Definitions: Significant Amount means an amount of a pollutant in a discharge that is amenable to available and reasonable methods of prevention, control, or treatment; or an amount of a pollutant that has a reasonable potential to cause a violation of surface or ground water quality standards or sediment management standards. • Water Quality Standards means the Water Quality Standards for Surface Waters of the State of Washington, Chapter 173-201A WAC, Ground Water Quality Standards (Chapter 173-200 WAC), Sediment Management Standards (Chapter 173-204 WAC), and human health-based criteria in the National Toxics Rule (40 CFR 131.36).

20. Municipal Codes Example: City of Seattle – Stormwater Manual Volume 3: Stormwater Flow Control and Water Quality Treatment Technical Requirements Manual. Directors’ Rules: 2009-005 SPU and 17-2009 DPD. Seattle Public Utilities and Department of Planning and Development, Seattle, WA.

21. Limiting Potential Sediment Site Liability

22. Understanding Control Objectives and Capabilities • Will conventional “80%” removal be sufficient? • What is feasible? • Life-cycle costs of treatment systems

23. Stormwater Control Options Operational BMPs Treatment BMPs Solids removal Filtration Receiving water

24. Passive/”Low-Tech” Stormwater Treatment …

25. … or Active/”High-Tech” Treatment Solids settling Conventional filtration Chemical coagulation Flocculation Ultrafiltration Solids removal Filtration Receiving water

26. Example of an Annual Budget for Stormwater Management • 30-acre facility • General industrial stormwater permit • “Low-impact” outdoor commercial activities NPDES quarterly sampling $ 2,000 Outfall solids removal/filtration $30,000 Catch basin cleaning/inserts $20,000 Pavement sweeping $15,000 Cleaning/inspecting pipes $10,000 Stormwater coordinator $20,000 Other/misc. $ 3,000 Total: $100,000

27. Stormwater, Other Sources, and the Uncertain Linkage to Sediment Quality

28. What can initiate an evaluation of sediment quality near outfalls? • Sediment site data point to a source • Upland facilities may be required to evaluate the potential for localized sediment recontamination in cleanup/restoration areas (source tracing) • Document baseline conditions relative to NRDA or property transfers • Other

29. Some Variables Stormwater: • Quality of stormwater data (grain size) Outfall: • Location, elevation and design of outfall • Discharge rates and frequencies Receiving water: • Depositional or scoured environment • Currents • Dredging history

30. Example 1

31. Example 1

32. Example 2 (recently dredged/ non-depositional) strong current

33. Stormwater outfall modeling for small point discharges Using stormwater data and receiving environment parameters to estimate receiving water impacts: • Environmental Fluid Dynamics Code (EFDC Hydro) Model • Boeing Stormwater Discharge/Receiving Water Assessment Model (in development)

34. Summary • Challenges of controlling stormwater sources: selecting effective options and measuring effectiveness • Stormwater at the facility level: uncertainty in estimating localized sediment impacts

35. Conclusions • Treatment of stormwater isn’t always required and should be considered in the context of other source control options • Demanding sediment site cleanup levels will require a better understanding of treatment performance • Stormwater management and control needs to consider all aspects and characteristics of the stormwater conveyance system

36. Internet Links to Related Topics • EFDC Model: http://gcmd.nasa.gov/records/EPA_EFDC.html • Puget Sound Stormwater Workgroup: http://www.ecy.wa.gov/programs/wq/psmonitoring/swworkgroup.html • City of Seattle Municipal Code (including stormwater): http://clerk.ci.seattle.wa.us/~public/toc/t22.htm • City of Seattle Stormwater Manuals: http://web1.seattle.gov/dpd/dirrulesviewer/List.aspx?leg=GD&t=Stormwater,%20Grading,%20and%20Drainage%20Control%20Code%20%28Ch.%2022.800%29 • National Parks Service Airborne Contaminants Assessment Project: www.nature.nps.gov/air/studies/air.../08_FactSheet_LoRes_smIm_letter.pdf • King County Atmospheric Deposition Sampling: http://www.kingcounty.gov/environment/wastewater/IndustrialWaste/SourceControl/Duwamish/Pollutants.aspx

37. Internet Links to Related Topics (contd.) • Department of Ecology – Industrial Stormwater Permit: http://www.ecy.wa.gov/programs/wq/stormwater/industrial/index.html • King County Stormwater Documents: http://www.kingcounty.gov/environment/waterandland/stormwater/documents.aspx • Stormwater Management Manual for Western Washington: http://www.ecy.wa.gov/programs/wq/stormwater/manual.html • Street and Municipal Sweeping Studies:http://www.worldsweeper.com/Street/Studies/index.html • Duwamish Slip 4: http://yosemite.epa.gov/r10/cleanup.nsf/ldw/Slip+4 • Lower Duwamish Waterway Source Control Investigation http://www.ecy.wa.gov/programs/tcp/sites/lower_duwamish/source_control/sc.html