Biofiltration for Stormwater Treatment Port of Vancouver, WA. Sheila Sahu, Senior Project Manager, Kennedy/Jenks Consultants Portland, Oregon

Transcription

1 Biofiltration for Stormwater Treatment Port of Vancouver, WA Sheila Sahu, Senior Project Manager, Kennedy/Jenks Consultants Portland, Oregon

2 Presentation Outline Introduction to Port s Biofiltration Systems Stormwater Challenges, Goals, and Limitations Grattix Box Design, Performance, and Sampling Results Terminal 2 (T2) System Design, Performance, Infiltration Testing and Sampling Results Maintenance Recommendations Summary of Findings

3 Two Successful Systems at the Port Grattix Box Biofiltration in a Tote (first installed 2008) T2 System Biofiltration System (installed 2009) 2016 Goals: Determine life span and maintenance needs

4 Stormwater Pollutant Challenges Sources everywhere (both municipal & industrial issues): TSS - dirt, tires, worn asphalt O&G - motor oil & hydraulic fluids Metals Zinc, Copper, Lead - from galvanized materials, dirt, roofs, fences, tires, shipping containers, etc. Pollutants fall from the sky through atmospheric deposition BMPs only help so much

5 Our Goals = WA ISGP Permit Benchmarks Quarterly Stormwater Sampling - Benchmarks Turbidity: 25 NTU (OR = 100 mg/l TSS) ph: Oil Sheen: none visible Petroleum Hydrocarbons: 10 mg/l Total Copper: 14 µg/l (OR = 20 µg/l) Total Zinc: 117 µg/l (OR = 120 µg/l)

6 Limitations of Conventional Methods Ponds, vaults, swales, engineered wetlands Proprietary systems can be expensive Large footprint= $$ Most focus on particle settling, residence time Ineffective for dissolved metals & colloids

7 Why Natural Systems? Capital Cost, O&M, sustainability More removal processes They work Mike Siegel / The Seattle Times

8 Grattix Box Biofiltration in a Tote

9 Grattix Box 2008 Pilot Study Performance Downspout Influent Downspout Effluent Total Zn (μg/l) Total Zn (μg/l) 11/20/ /25/ /12/ ND (<5) 12/29/ ND (<20) Benchmark 117 μg/l

10 Grattix Box 2016 Performance Evaluation Three samples collected in each profile depth 0-4 surface deposition 6-10 middle of soil mix sand Laboratory analyses for: RCRA 8 metals plus Copper and Zinc Sieve and Hydrometer

11 Grattix Box 2016 Media Sampling Results Filter Media Sampling Results

12 T2 System Biofiltration in a Bigger Box 23,650 square feet (0.54 acres) Receives untreated stormwater from 60 acres of impervious area Previous bioswale Current configuration

13 T2 System Performance 4 years after install, port achieved consistent attainment (8 consecutive quarterly sampling events meeting ISGP benchmarks) Allows for 3-year sampling suspension; need to resume sampling in 2017

14 T2 System 2016 Performance Evaluation Three samples collected in each profile depth 0-4 surface deposition 8-14 middle of soil mix bottom of soil mix Laboratory analyses for: RCRA 8 metals plus Copper and Zinc Sieve and Hydrometer Organic Content Cation Exchange Capacity (CEC) Infiltration Testing

15 T2 System 2016 Performance Evaluation Invasive Weeds Surface Deposition

16 T2 System Infiltration Testing and Sampling

17 T2 System Infiltration Testing Results 2016 Measured Infiltration Rates

18 T2 System Media Sampling Results (Metals) Number of Samples Range (mg/kg) Median (mg/kg) Metal Copper Top Middle Bottom Lead Top Middle Bottom Zinc Top Middle Bottom Grattix Box (comparison)

19 T2 System Media Sampling Results (CEC & OC) Highest Metals Capture

20 T2 System and Grattix Particle Size Distribution Uniformity Coefficient (Uc) = (D60) / (D10) Uc= 4 or less recommended BUT higher Uc= higher metals capture Wide media grading with fines is more effective than narrow grading

21 Final Maintenance Recommendations

22 Annual Maintenance Till in compost to top 4 inches Remove surface sediments and replant Remove invasive weeds

23 Summary The T2 System and Grattix Boxes are currently effectively treating stormwater: Metals removal through sedimentation, filtration, and adsorption Filter media has high infiltration rates and is predicted to last a total of 35 years based on current organic content Maintenance activities: Revegetation Amendments to the filter media Flow routing management Current data gaps: Effluent sampling from T2 System and Grattix boxes to identify breakthrough Organic content in Grattix boxes to more accurately predict filter media life

24 Successful Construction Methods

25 Questions? Kennedy/Jenks Stormwater Blog