Biofiltration and Downspout Filter Media Evaluation for BMP Decision-Making at the Port of Vancouver, WA

Sheila Sahu, Kennedy/Jenks ConsultantsPortland, OR

Matt Graves, Port of VancouverVancouver, WA

StormCon

August 30th, 2017

Presentation Outline

►Introduction to Treatment Systems

►Stormwater Challenges, Goals, and Limitations

►Design and Performance (Overview) | Infiltration Testing and Sampling Results (In-Depth):

■Terminal 2 (T2) System

■Grattix Box

►Summary of Findings

►Annual Maintenance Recommendations

Two Successful Treatment Systems at the Port

► T2 System– Large Biofiltration System

■ Installed 2009

► Grattix Box– Biofiltration in a Tote

■ First installed 2008

■ Name derived from (Matt) Graves/ (Mary) Mattix combo

Stormwater Pollutant Challenges

► Sources everywhere (both municipal & industrial issues):

■ TSS – dirt, tires, worn pavement

■ O&G – motor oil & hydraulic fluids

■ Metals – zinc, copper, lead from galvanized materials, paint, dirt, roofs, fences, tires, shipping containers, etc.

► Pollutants fall from the sky through atmospheric deposition

► BMPs only help so much

Our Goals = WA ISGP Permit Benchmarks

► Quarterly Stormwater Sampling - Benchmarks

■ Turbidity: 25 NTU

■ pH: 5.0-9.0

■ Oil Sheen: none visible

■ Petroleum Hydrocarbons: 10 mg/L

■ Total Copper: 14 µg/L

■ Total Zinc: 117 µg/L

► Port discharge routed to Columbia River

Limitations of Conventional Methods

► E.g., ponds, vaults, swales, engineered wetlands

► Proprietary systems can be expensive

► Large footprint= $$

► Most focus on particle settling, residence time

► Ineffective for dissolved metals & colloids

Why Natural Systems?

► Capital cost, O&M, sustainability

► More removal processes

► They work

Mike Siegel / The Seattle Times

T2 System – Large Biofiltration System

►23,650 square feet (0.54 ac)

►Treats 60 ac impervious

►Peak inflow rate= 18.2 cfs (~5-yr, 24-hr storm event, 2.8”)

►Design includes:

■Sedimentation basin

■Underdrains

■Collector line

■CBs (1-ft max. ponding)

■Sampling port

Sedimentation Basin

Underdrain (typical)

Collector Line

Sampling Port

CBs

T2 System – 2009-2013 Performance

► Port achieved consistent attainment (8 consecutive quarterly sampling events meeting ISGP benchmarks) 4 years after install

► Allows for 3-year sampling suspension; will resume sampling in 2017

Discharge Monitoring Report (DMR)

T2 System – 2016 Performance Evaluation

► Samples collected in each profile depth (red, pink, blue dots):

■ 0-4” surface deposition

■ 8-14” middle of soil mix

■ 23-36” bottom of soil mix

► Infiltration Testing (blue dots; Ecology Pilot Infiltration Test)

T2 System – 2016 Performance Evaluation

Invasive Plants Surface Deposition

Cirsium arvense

(Canada thistle)

Equisetum arvense

(Field horsetail)

Grattix Box – Biofiltration in a Tote

► http://www.portvanusa.com/assets/Grattix-how-to-flyer.pdf

One box

treats max.

5,000 sq. ft.

Grattix Box – 2008 Pilot Study Performance

Downspout Influent Downspout Effluent

Total Zn (μg/L) Total Zn (μg/L)

11/20/08 295 21.3

11/25/08 947 14.7

12/12/08 278 ND (<5)

12/29/08 213 ND (<20)

Benchmark ≤117 μg/L

Grattix Box – 2016 Performance Evaluation

► Samples collected in each profile depth (3 boxes):

■ 0-4” surface deposition

■ 6-10” middle of soil mix

■ 10-16” bottom of soil mix/sand

► Infiltration Testing (single-ring infiltrometer)

2009

20122016

T2 System and Grattix Box Results

► Infiltration Testing

►Laboratory analyses for:

■RCRA 8 metals plus Copper and Zinc

■Cation Exchange Capacity (CEC)

■Organic Content (OC)

■Sieve and Hydrometer (Particle Size)

Infiltration Testing Results

► BMPs had high infiltration rates compared with recommended (2-12 in/hr)

► Higher T2 System rates likely due to larger testing area, no ring restriction

► >Gravel surface samples = high constant head rate>Sand bottom samples = high falling head

Media Sampling Results (Metals)

Metal

Number of

Samples

Range

(mg/kg)

Median

(mg/kg)

Copper

Top 9 26.5-83.7 58.5

Middle 9 12.7-33.5 15.5

Bottom 3 5.82-7.34 6.63

Lead

Top 9 15.7-45.5 21.2

Middle 9 8.69-18.3 10.7

Bottom 3 5.36-7.09 5.55

Zinc

Top 9 277-556 346

Middle 9 153-283 202

Bottom 3 50.2-72.6 67.2

T2 System

Grattix Boxes

Sample T2 System ProUCL Box Plot

Media Sampling Results (CEC & OC)

Highest

Metals

Capture

(top samples

>CEC & OC)

► Soil mix is 40% compost, 60% sand by volume

Particle Size Distribution

► Uniformity Coefficient (Uc) = (D60) / (D10)

► Uc= 4 or less recommended

► BUT higher Uc= higher metals capture

► Conclusion: Widely graded with fines is more effective than narrowly graded

► Assumption: Origination of fines is not runoff

Highest Metals Capture

Summary of Findings

► T2 System and Grattix Boxes are successfully treating stormwater metals

■ Primary processes are sedimentation, filtration, and adsorption

■ 2016 sampling shows Grattix Boxes <benchmarks and T2 System slightly >Cu benchmark; maintenance can restore performance

► Filter media:

■ has high but effective infiltration rates

■ can be max. 16-20 inches deep; top 4-inch layer with >OC is key

■ is predicted have a 30-year lifespan prior to breakthrough (defined as effluent= 10% influent concentrations) based on top sample OC

■ is under Toxic Characteristic Leaching Procedure (TCLP) regulatory levels, but high total Cu levels may fail WA state book designation and be characterized as dangerous waste without bioassay results

Annual Maintenance Recommendations

Remove surface sediments

and revegetate

Remove invasive

plants/replace with plants

with deeper root structure

Till in compost to top 4 inches

Clean catch basins Clean basin, pipes & downspouts

Daucus carota

(Queen Anne’s lace)

Questions?

sheilasahu@kennedyjenks.commgraves@portvanusa.com