DESIGN OF ADVANCED BIORETENTION SYSTEMS, Delaware, Washington

TerraSolve LLC September 1, 2010

DESIGN OF ADVANCED BIORETENTION SYSTEMS,

Delaware, Washington and Virginia

2010 National Hydraulics Engineering Conference

Salt Lake City, Utah August 2010

Steve Sisson

Delaware Department of Transportation

and

Bill Lucas

TerraSolve LLC


OVERVIEW

DELAWARE’S RUNOFF ISSUES

BENEFITS OF IMPERVIOUS AREA DISCONNECTION

DESIGN OF ADVANCED BIORETENTION SYSTEMS

FIELD INSTALLATIONS OF ADVANCED

BIORETENTION SYSTEMS


Delaware’s Water Bodies

Delaware 303(d) List Fact Sheet

•377 Bodies of Water

• 90 percent are listed as impaired by EPA

standards

• Primary Sources of Impairments are

Phosphorus and Nitrogen

http://www.dnrec.state.de.us/water2000/Sections/Watershed/ws/links.htm


Sources of Nutrients

•Varies by Watershed, Airshed & Land Use

•Agriculture

•Atmospheric Deposition

•Stormwater/Urban Land Use

•Wastewater



Real Problems for the Inland Bays

• Fish Kills

• Dead Zones

• Staph Infections

• Decreased Recreational and Property Values

http://www.epa.gov/reg3wapd/nps/success/de_inland_bays.htm



Legislative Background

•June of 1990, Stormwater Management added to Chapter 40, Title 7, of the Delaware Code

•April 2005, Green Technology Revision

•July 1995, DelDOT named a Delegated Agency

•November 2008, Inland Bays PCS

•January 2011, Volumetric Approach and Full Implementation of TMDL’s



Green Technology

• Green Technology: The Delaware Urban Runoff Management Approach (Lucas, 2004)

• Delaware Urban Runoff Management Model (DURMM)

• Approach Promotes Reductions in Effective Impervious Area Through Disconnection Practices & Biofiltration Swale and Bioretention BMPs

http://www.swc.dnrec.delaware.gov/Pages/SedimentStormwater.aspx



MODELING IMPERVIOUS AREA DISCONNECTION


FIRST, REDUCE RUNOFF VOLUMES BEFORE BIORETENTION BMPs

Swales, side slopes (=filter strips) substantially reduce runoff volumes.

See Delaware’s Green Technology Manual and DURMM model

(Lucas, 2004).

Runoff is additional rainfall applied to the wetted pervious surfaces.

Runoff reduction varies from very little to as high as 95%.

Depends upon hydraulic loading, wetted area, and infiltration rate.

Soil amendments greatly improve infiltration rates.

Relatively little effort compared to installing stormwater control BMPs.

So disconnection should be the first option for SCM design.

However, rarely computed explicitly, surprising, considering its potential.


2.0 INCH RAIN = 1.97

INCHES RUNOFF,

AT 60’ BY 30’ ROOF,

= 295 CU.FT. RUNOFF

IF IMPERVIOUS CONNECTED:

TOTAL RUNOFF= 305 CU. FT.

2.0 INCH RAIN = 0.20

INCHES RUNOFF,

AT 600 SQ.FT. LAWN,

= 10 CU.FT. RUNOFF

295 CU.FT. / 600 SQ.FT, = 5.9

INCHES, ADD 2.0 INCHES

RAIN, TOTAL = 7.9 INCHES

RAIN, = 2.89 INCHES

RUNOFF

IF IMPERVIOUS DISCONNECTED:

TOTAL RUNOFF= 145 CU. FT.

REDUCTION = 52.5%

600 square foot pervious

wetted area

1800 square foot

impervious area

SCHEMATIC CONCEPT OF RUNOFF REDUCTION DUE TO DISCONNECTION


SCHEMATIC LAYOUT OF 67% IMPERVIOUS SITE, FULLY DISCONNECTED

Schematic Layout of Disconnected Site

Site is 4.92 acre commercial/ office

complex used in DURMM model.

To promote sheet flow, parking

drains into perimeter bioswales

with no curb.

Perimeter bioswales convey runoff

down 10:1 side slopes into the

bottom width of 4-10 feet.

Roof runoff from office buildings

dispersed over lawn to inlets

between buildings.

Commercial roof runoff conveyed

to top of southern bioswale.

Central parking conveyed to head

of southeast bioswale.

N


Exceedance

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

0

1

2

3

4

5

6

7

8

9

10

11

1AM15 Mon Aug 2005

2AM 3AM 4AM 5AM

Ra

infa

ll (

in/h

r)O

utflo

w (

cfs

)

Date/Time

S10 FullDisconnection0.25-2005 System NoDisconnection1.0-2005 System FullDisconnection0.25-2005 System System FullDisconnection1.0-2005

Event From: 8/15/2005 12:17:57 AM To: 8/15/2005 5:13:13 AM (4.92 hours)

Site modeled with no

disconnection at 1.0

in/hr, with disconnection

at 0.25 & at 1.00 in/hr.

Disconnection delays

runoff for 25 minutes.

The 0.25 in./hr. scenario

had 23% reduction in

peak flow, even with

runoff volume reduced

by only 7%.

1.0 in./hr. scenario had

peak reduction of 43%.,

with runoff reduced by

30%.Maximum Rainfall(in/hr):3.444 Rainfall(in):1.175

Scenario: None1.0 Full0.25 Full1.0

Maximum Outflow (cfs): 10.72 8.342 6.089

Mean Outflow (cfs): 0.7856 0.7293 0.5484

Total Outflow (ft³): 13,920 12,920 9,716


Event From: 1/14/2005 4:54:19 AM To: 1/14/2005 6:06:33 PM (13.2 hours)

Less intense frontal event,

with lower peak intensity.

Disconnection eliminates

runoff for first hour.

At 0.25 inch/hour, peak

reduction was 57%, &

volume reduced by 28%.

At 1.0 in/hr, peak

reduction was 94%, &

volume reduced by 95%.

This demonstrates how

disconnection can very

substantially reduce peaks

and volumes. Maximum Rainfall(in/hr):0.768 Total Rainfall(in):1.679

Scenario: None1.0 Full0.25 Full1.0

Maximum Outflow (cfs): 2.354 1.007 0.1445

Mean Outflow (cfs): 0.4089 0.2955 0.02022

Total Outflow (ft³): 19,440 14,050 961

Exceedance

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

6AM14 Fri Jan 2005

9AM 12PM 3PM 6PM

Ra

infa

ll (

in/h

r)O

utflo

w (

cfs

)

Date/Time

S1 FullDisconnection0.25-2005 S1 FullDisconnection1.0-2005 System System FullDisconnection0.25-2005 System FullDisconnection1.0-2005


2005 DESIGN YEAR RESULTS

Disconnection Scenario (in./hr.):

None (1.00) Full (0.25) Full (1.00)

Maximum Outflow (cfs): 10.72 8.342 (22.2%) 6.089 (43.2%)

Total Outflow (ft³): 438,700 173,600 (60.4%) 63,300 (85.6%)

With effective disconnection alone, you can obtain excellent

hydrological performance even at over 67% impervious, without the

need for any specific BMP.

Bioswales and filter strips can be landscaped as part of the required

perimeter buffer placed on this site.

Same approach equally valid for highway side slopes and swales.

Runoff rates and volumes substantially reduced over 2005 design year. (Percentage reductions shown in parentheses.)


DESIGN OF ADVANCED BIORETENTION SYSTEMS


Bioretention may be effective for TSS, particulate nutrients,

hydrocarbons, and metals.

However, not effective in removing dissolved phosphorus (P) over long

periods of time without losing performance.

Also, not very effective in lowering dissolved nitrogen (N) loads. In

particular, nitrate retention often very low or negative.

Meanwhile, strict discharge limitations are being imposed as part of the

Total Maximum Daily Load (TMDL) allocations by USEPA.

Optimal combination of media properties, retention time, and presence of vegetation has a very beneficial effect on nutrient reduction.

WHY IMPROVE BIORETENTION TECHNOLOGIES?


Media is a blend of sand, topsoil, water treatment residuals (WTRs), &

organic components.

Media components are selected to provide the following:

High flow rates intercept more runoff and avoid potential clogging.

High efficiency in removing particulate pollutants and pathogens.

Very high efficiency in removing and retaining P, with retention

rates exceeding 90%, even after decades of stormwater loads.

Documented in the scientific literature, these findings are being

replicated in large-scale experiments in WA, DE and VA.

COMPONENT 1 –ENGINEERED MEDIA.


Stormwater inflow and outflow relative to plant uptake after 32 years:

The WTR systems remained 99% effective for PO4 retention, and over 90% effective for TP retention (Lucas and Greenway, 2010).

P retention improved over time and after even more accumulated loads. Recent data year later shows no decrease in retention. Loads now equivalent to over 5 decades of runoff loads.

ADVANCED MEDIA TESTING

0.010 mg/l

c) 5-Mar-09

99%

87%

55%

(24%)

96%

85%

95%

91%

53%

99%

94%

a -1%

cd 78%

bc 65%

bc 75%

40%

a 18%

e 92%

de 88%

e 93%

n/a

42%

0.0 0.1 0.2 0.3 0.4 0.5

a) 1-Mar-08

61%

45%

-109%

33%

69%

70%

78%

34%

89%

93%

90%

27%

89%

91%

89%

75%

75%

71%

61%

34%

36%

0.0 0.1 0.2 0.3 0.4 0.5

Inflow

Net Inflow

K20 nv

K20

K10/40

K40

RM06

RM10

Net Inflow

WTR-K

WTR-K nr

WTR30

TREATMENT

After uptake

K20, No Plants

20% Krasnozem

10%/40% Krasnozem

40% Krasnozem

6% Red Mud

10% Red Mud

After Uptake

WTR- Krasnozem Blend

No Outlet WTR-K

30% WTR


Media Saturated Hydraulic Conductivity (Ksat) Testing:

Conductivity rates range from 14 inches (35cm) to 52 inches (130cm) per hour.

The individual replicates of each media treatments were quite variable. This demonstrates inherent variability of natural systems.

These high rates provide only very limited retention time for N removal processes.

b) February 24- March 15, 2009

0

50

100

RM

06

RM

06

RM

06

RM

10

RM

10

RM

10

K20

K20

K20

K20nv

K20nv

K20nv

K10/4

0

K10/4

0

K10/4

0

K40

K40

K40

WT

R30

WT

R30

WT

R30

WT

R-K

WT

R-K

WT

R-K

WT

R-K

nr

WT

R-K

nr

WT

R-K

nr

10 11 12 1 2 3 7 8 9 13 14 15 16 17 18 4 5 6 19 20 21 22 23 24 25 26 27

Ksat (c

m/h

r)

ADVANCED MEDIA TESTING

40 in./hr.


Dual Stage Outlet Control Structure controls flows passing through the media.

The Lower Stage Outlet manipulated to provide saturated zone of different depths.

Lower Outlet aperture extends residence time for improved N removal.

Saturated zone improves N removal, and retains moisture to avoid drought stress.

The Upper Stage Outlet is manipulated to permit high flows to pass

through the media in even large runoff events.

Treats even substantial events with minimal untreated bypass flow.

Provides ability to maintain infiltration rates as media clogs over time.

COMPONENT 2 – OUTLET CONTROLS


• Lower outlet extends detention time during small events for best N

removal performance.

• Upper outlet conveys peak flows in large events through the media so it

is also treated for TSS, metals and particulate nutrients.

• The elevations of both upper and lower outlets are adjustable, as is the

aperture of the lower outlet.

Plan and End Views of Outlet Structure

UDEL COLLECTION SYSTEM – OUTLET PLAN AND END VIEW

Van

Stone

Flange

Upper

Outlet

Lower

Outlet

4”

Under-drain

Weir

Plate

4” Knife

Valve

Overflow

Grate


With outlets without outlets

90 minute rainfall duration represents 1.5 inch rainfall event. Equals

six month recurrence interval for Brisbane AU.

Outflow lasts for over 8 hours in outlet-regulated system. Average

retention time is 150 minutes.

However, peak flows are treated, shown by the upper outlet flow.

Compare to only 2 hours of flow in the no outlet free discharge

system. Average retention time is 18 minutes.

COLLECTION SYSTEM - MODELED HYDRAULIC RESPONSE

b) Free Discharge Response

0.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.010

0 1 2 3 4 5 6 7 8 9

Elapsed Time (hr.)

Flo

w R

ate

(cu.m

/sec)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Ele

vatio

n (

m)

Inflow

Into Media

Outlet

Media Elevation

a) Outlet Controlled Response

0.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.010

0 1 2 3 4 5 6 7 8 9

Elapsed Time (hr.)

Flo

w R

ate

(cu.m

/sec)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Ele

vatio

n (

m)

Inflow

Into Media

Upper Outlet

Lower Outlet

Media Elevation

Stone Elevation

Media Surface

Upper

Outlet

Lower

Outlet


Unlike P retention, nitrogen retention determined by processes of:

Uptake by plants directly into roots

Immobilization by microbes, which is supported by plants

Denitrification, which is also ultimately driven by plants.

As a result, N removal is a function of plant vigor, density, and time of year. Older plants will remove more N than plants that are immature.

N removal processes are promoted by increases in retention time and saturated conditions.

In sandy soils of the coastal plain where hydraulic conductivity can be as fast, media will drain too rapidly for effective N removal.

Therefore, a geomembrane is used to collect treated runoff for control by Dual Stage Outlet to ensure adequate longer retention time.

NITROGEN REMOVAL PROCESSES


NOx removal by outlet controlled WTR-K system ranges between 62-

76%, while TN removal ranges from 35 to 66%.

Outlet controlled WTR-K system performed much better than

equivalent free discharge WTR-Knr system. Differences significant.

This confirms effectiveness of the outlet for large event. Better removal

would occur in smaller events where retention time would be longer.

a) High Concentration Runs:

a 19%

b 62%

bc 76%

c 78%

bc 67%

bc 62%

a

bc 76%

a 34%

66%

(45%) a

n/a

a 31%

a 27%

b 66%

b 57%

62%

b 53%

b 64%

b 64%

b 52%

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

Inflow

Net Inflow 1

K20nv

K20

K10/40

K40

RM06

RM10

Net Inflow 2

WTR-K

WTR-K nr

WTR30

b) Low Concentration Runs:

a 28%

b 76%

b 74%

b 76%

b 71%

b 73%

a

b 70%

b 60%

119%

(30%) a

n/a

b 36%

ab 2%

ab 35%

ab 25%

112%

b 50%

b 42%

b 43%

b 34%

0.0 0.2 0.4 0.6

COLLECTION SYSTEM - OBSERVED NITROGEN RESPONSE

OUTLET

NO OUTLET


FIELD INSTALLATIONS OF

ADVANCED BIORETENTION DESIGNS


OVERALL LAYOUT OF EXPERIMENTAL BMPs AT WSU

• Runoff collected from 1.7 acre

fuel depot/maintenance facility.

• Partitioned between 16 rain

gardens and 20 mesocosms.

• 15’ by 15’ rain gardens use WA

media (sand & 40% compost v/v).

• Mesocosms use two compost/

sand mixtures, one WTR/sand

mixture, one combination WTR &

WA mixture and one biosolids

mixture (maybe).

• Flows distributed by gravity so

operate as BMPs even when not

running experiments.

• Advanced outlets in all systems.

Rain Garden

Experiments

Mesocosm

Experiments

Mixing and Distribution

Tanks

Source Area

Interception


OUTLET STRUCTURE AT WASHINGTON STATE UNIVERSITY

• Outlet structure has dual outlets,

both of which are adjustable in

elevation and aperture.

• Pressure transducer measures

elevation in outlet (equal to

hydraulic grade in stone).

• Flows measured by tipping bucket

so rating curves can be developed

for flows through the outlet.

• Bypass used as control for typical

free discharge configuration.

• Knife valves used to control outlet

configuration and provide for falling

head measurements.

Upper Outlet

Lower

Outlet


• Routing diagram shows how

system modeled to ensure that

collection, distribution and

conveyance do not introduce

backwater effects that would

affect equal distribution of

captured flows.

• Systems include hydraulic

cells, upper rain garden ( to

evaluate inflows), lower rain

garden (to evaluate outflows),

and mesocosms.

• All hydraulic losses in the

entire system explicitly

modeled, including effect of

ponding in treatments upon

inflow weir arrays.

ROUTING APPROACH FOR EXPERIMENTAL BMPs AT WSU


OVERALL LAYOUT OF RETROFIT BMPs AT SCIENCE MUSEUM OF VIRGINIA


• Three outlets are used: a drain outlet with a small opening used to

“equalize” infiltration rates, a lower outlet for extended detention, and an

upper outlet to convey peak flows through the media.

• Smart Drains convey laminar flow according to Darcy’s Law, and cannot

be clogged even in clay, ensuring flow through drain and lower outlet.

Plan and End Views of Outlet Structure

SMV COLLECTION SYSTEM – OUTLET PLAN AND END VIEW

2” PVC

with Smart

Drains

Van

Stone

Flange

Upper

Outlet

Drain

Outlet

Lower

Outlet

4” Inflow

Weir

Plate

4” Knife

Valve

10” Outflow

Overflow

Grate


U. DELAWARE ADVANCED BIORETENTION SYSTEMS- OVERALL LAYOUT

• Advanced media contains P retaining material, DNREC media is DE

approved media. Systems separated by membrane lined plywood barrier.

• Inflows measured by Palmer-Bowlus flumes, with peak flows bypassed to

keep large events from overloading systems.

• Outflows collected by triple outlet systems.

Plan view of Diversion, Bioretention Cells, and Outlets


• Membrane lined divider separates different media inflows and outflows.

• 1-foot layer of Rice Gravel captures treated runoff. Stone small enough

that filter fabric not needed, avoiding potential clogging.

U. DELAWARE ADVANCED BIORETENTION SYSTEMS- SYSTEM SECTION

Section through Media and Stone of Bioretention Cell


Randy Greer, Delaware Dept. of Natural Resources and

Environmental Control.

Curtis Hinman, Washington State University, Puyallup

Extension Station.

David Sample, Virginia Tech. Dept. of Biological Systems

Engineering.

Carmine Balascio, University of Delaware, Dept. of

Bioresources Engineering.

Washington State Department of Ecology.

U.S. National Fish and Wildlife Service.

Delaware Clean Water Advisory Council.

ACKNOWLEDGEMENTS


IMPERVIOUS AREA DISCONNECTION REFERENCES

Ahearn, D., and R. Tveten. 2008. Legacy LID: Stormwater Treatment in Unimproved Embankments Along Highway Shoulders in Western Washington. In: International Low Impact Development Conference, November 16-19, 2008, Seattle, Washington.

Barrett, M.E. 2004. Performance and Design of Vegetated BMPs in the Highway Environment. In: Critical Transitions In Water And Environmental Resources Management, Proceedings of The 2004 World Water and Environmental Resources Congress, June 27-July 1, 2004, Salt Lake City, Utah.

Caltrans. 2003. Final Report: Roadside Vegetated Treatment Sites (RVTS) Study. CTSW-RT-03-028, Caltrans Division of Environmental Analysis, Sacramento, California.

Herrera. 2009. Final Project Report: Compost-Amended Vegetated Filter Strip Performance Monitoring Study. Prepared for Washington State Department of Transportation, by Herrera Environmental Consultants, Inc., Seattle, Washington.

Kaighn, R.J., and S.L. Yu. 1996. Testing of Roadside Vegetation for Highway Runoff Pollutant Removal. Transportation Research Record 1523:116-123.

Kearfott, P.J., M.P. Aff, M.E. Barrett, and J.F. Malina. 2005. Stormwater Quality Documentation of Roadside Shoulders Borrow Ditches. IDS-Water White Paper 179, Center for Research in Water Resources, University of Texas, Austin, Texas.

Lancaster, C.D. 2005. A Low Impact Development Method for Mitigating Highway Stormwater Runoff - Using Natural Roadside Environments for Metals Retention and Infiltration. Masters Thesis, Washington State University, Department of Civil and Environmental Engineering, Pullman, Washington, 157 pp.

Lantin, A., and M. Barrett. 2005. Design and Pollutant Reduction of Vegetated Strips and Swales. In: World Water Congress 2005, May 15, 2005, Anchorage, Alaska.

Reister, M., and D.R. Yonge. 2005. Application of a Simplified Analysis Method for Natural Dispersion of Highway Stormwater Runoff. Prepared for Washington State Department of Transportation, by Washington State Transportation Center - Washington State University, Pullman, Washington.

Yonge, D.R. 2000. Contaminant Detention in Highway Grass Filter Strips. Report No. WA-RD 474.1, Washington State Department of Transportation, Olympia, Washington.

QUESTIONS?

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DESIGN OF ADVANCED BIORETENTION SYSTEMS, Delaware, Washington