Iron-Enhanced Ditch Checks in Roadside

Drainage Ditches Can Mitigate Runoff

Poornima Natarajan

John S. Gulliver

University of Minnesota

Barbara Loida, Nick Olson, David Bauer,

James Michael, Scot Way

Minnesota Department of Transportation

Kristine Giga and Ryan Johnson

City of Roseville

Roadside Drainage Ditches

• Convey, infiltrate

stormwater runoff

• Ditch checks for

erosion control

– Increase water

storage, infiltration

• Water quality

functions

– Filter out solids and

associated pollutants

http://www.deldot.gov/stormwater/images2/stone_creek_dam_

full.jpg

Riprap

Ditch Check

Phosphorus: Critical Pollutant

• Total phosphorus (P)

= Particulate + Dissolved

• Dissolved P

– Bioavailable => algae bloom

– ~45% total P load in runoff (Maestre and Pitt 2005; Kayhanian et al. 2012)

– ~0.44 kg P per lane mile paved road

• Treatment requires engineered media

– Not part of typical ditch, ditch check designs

Research need: Increased dissolved P removal

• Maestre, A., and Pitt, R. (2005). The National Stormwater Quality Database, Version 1.1: A Compilation and Analysis of NPDES Stormwater Monitoring Information.

University of Alabama, Tuscaloosa, AL, and Center for Watershed Protection, Ellicott City, MD.

• Kayhanian, M., B. Fruchtman, J. S. Gulliver, C. Montanaro, E. Raniere and S. Wuertz, (2012). “Review of Highway Runoff Characteristics:: Comparative Analysis and

Universal Implications,” Water Res., 46(9), 6609-6624.

http://water.me.vccs.edu/waterplant/algaebloom.jpg

Iron-Enhanced Sand Filtration for

Stormwater Treatment

• Sand filter containing iron shavings

– Specifically for dissolved phosphorus capture

– Laboratory tests: 4.8 mg P retained/g iron (Erickson et al. 2006, 2012)

• Current Applications in MN:

– Vertical-flow sand filters

• Erickson, A. J., Gulliver, J. S. and Weiss, P. T. (2007). “Enhanced sand filtration for storm water phosphorus removal." J. Environ. Eng., 133(5), 485-497.

• Erickson, A. J., Gulliver, J. S., and Weiss, P. T. (2012). “Capturing phosphate with iron enhanced sand filtration.” Water Res., 46(9), 3032-3042.

http://www.life-treasure.com/technology.html

Photo Courtesy: Andy Erickson

Maplewood, MN

Iron shavings

Iron-Enhanced Ditch Check

• Incorporate iron-enhanced sand filter as an

“insert” in a ditch check

Applications/Advantages:

– Relatively inexpensive

– Installation in limited right-of-way, poor drainage soils

Objectives and Tasks

Design, install, and assess iron-enhanced ditch checks

for dissolved phosphorus capture in roadside ditches

• Design development

– Laboratory tests

– Full-scale design

• Construction

– Washington County (prev. MnDOT ROW) and City of

Roseville

• Performance Assessment

– Field monitoring and field testing

• Season 1 (2015)

Design Development

(Ahmed et al. 2014)

(Natarajan and Gulliver 2015)

• Laboratory prototype

– Flume tests @ SAFL• C-33 sand-iron media

• Re-design w/ coarser media

– Column tests • 92.5% Sand and 7.5% Iron (by wt)

• Ksat = 0.046 cm/s (79 in/hr)

• Two designs for MnDOT and City

of Roseville project sites

• Ahmed, F., Natarajan, P., Gulliver, J.S., Weiss, P.T. and Nieber, J.L. (2014). Assessing and Improving Pollution Prevention by Swales, Final Report 2014-30, Research

Services and Library, Office of Transportation System Management, Minnesota Department of Transportation, St Paul, MN. <http://www.lrrb.org/PDF/201430.pdf>

• Natarajan, P., and Gulliver, J.S. (2015). “Assessing iron-enhanced swales for pollution prevention.” Final Report prepared for the U.S EPA Section 319 Program and

Minnesota Pollution Control Agency. University of Minnesota Digital Conservancy, http://hdl.handle.net/11299/175560.

Site #1: Stillwater Ditch Check (prev. MnDOT ROW)

Stillwater, Washington County, MN

Drainage area = 0.74 ac

Existing soil

berm

5/2013

1 2

34

9/2014

Performance Assessment: Field Monitoring

• Sand-iron filter insert performance

– Storm events (Summer 2015)

– Composite WQ Samples

• Ortho-phosphate

• Event mean concentration

– P mass removed in treated runoff volume Sampling location

**Not drawn to scale**

Instrumentation in Monitoring well

Sampling tube from

ISCO sampler

Pressure transducer

2015 Field Monitoring ResultsStillwater Ditch Check Insert

Phosphate = ortho-P

Volume Exceedance and Phosphate Mass Reduction

Stillwater Ditch Check Insert

2015

Total Runoff Volume Treated = 68,263 L

Total Phosphate Mass Load In = 24.1 g

Cumulative Phosphate Mass Reduction = 42%

Site #2: City of Roseville Ditch Check

1.8 m L x 0.15 m W x 0.38 m H

Field Testing

• Water truck (~7600 L capacity)

• Phosphorus added to water

• ~2.5-hr tests

• Filter outflow @ 10-min (catch

and weigh method)

• Grab water samples @10- or

20-min for [ortho-P]

• 3 tests in Summer 2015

Ditch Check

Gu

tte

r

Field Testing: Test #1 Results

Upstream head at check dam = ~0.15 m (6 in)

7/24/15

Total Phosphate Mass Reduction = 49.7%

DateTest

Scenario

Volume

Input

(m3/m2)*

Phosphate

Cin

(mean)

Phosphate

Cout (mean)

Phosphate

Massin

Total Mass

Removal

Test #2

8/7/15

High head,

high P input0.25 320 µg/L 240 µg/L 0.936 g 26.7%

Test #3

8/14/15

Low head,

high P input0.22 330 µg/L 190 µg/L 0.464 g 42.2%

Upstream swale basin area = 38 m2

Iron-Enhanced Ditch Checks Can

• Increase dissolved P capture in drainage ditches

– 30 to 50% input mass load reduction

– In-series installation for greater reduction

• Improve overall and downstream WQ, mitigate

roadway runoff impact

• Long-term performance and maintenance needs yet

to be investigated

Existing Ditch Side

Filter Insert

Ditch Bottom

Lessons, Guidelines

• Proper sealing (and width) to prevent runoff bypass

• Alternate design with multiple filter socks

– Site conditions, future maintenance, cost

– Filter frame enclosure

• Quality of iron

Acknowledgements

Project Sponsors and Partners

• Minnesota Pollution Control Agency (US EPA 319 Grant)

• MN Department of Transportation

• City of Roseville

• Local Road Research Board

Project Support

• Prof. Peter Weiss, Valparaiso University

• St. Anthony Falls Laboratory (D. Christopher, C. Ellis, B. Erickson, R. Gabrielson)

• Undergraduate research assistants (D. Liddell, A. Poovey, T. Olsen, J. Pham)

Contact Information: Poornima Natarajan

pnataraj@umn.edu