Evaluating the Hydrologic and Water Quality Performance of ...northcarolina.apwa.net/Content/Chapters/northcarolina.apwa.net/File... · Evaluating the Hydrologic and Water Quality

Evaluating the Hydrologic and Water Quality Performance of Infiltrating

Wet Retention Ponds

Joshua Baird, E.I.Town of Morrisville

Bill Hunt, Ph.D., PERyan Winston, PENorth Carolina State University

www.bae.ncsu.edu/stormwater


Forested Watershed (Swift et al., 1987)

ET = 50%

Runoff = 5%

Infiltration = 45%


Developed Watershed (US EPA, 1993)

ET = 30%

Runoff = 55%

Infiltration = 15%


Why is increased runoff (stormwater) bad?

• Decreased groundwater recharge

• Increased flooding• Increased peak flow rates• Increased nutrients,

metals, sediment, and pathogens to receiving bodies

• Thermal pollutionPhoto Credit: Bill Lord


Hydrograph


Stormwater Regulations

• Clean Water Act – 1972• National Pollution Discharge Elimination System (NPDES) – Phase 1 ‐ 1990

• NPDES – Phase 2 ‐ 2003• Energy Independence and Security Act – 2007• Specific State regulations to protect certain water resources


Stormwater Control Measures (SCM)

Stormwater WetlandBioretention

Permeable Pavement

Grassed Swale

Wet Retention PondDry Detention Basin

Images from NC DEMLR BMP Manual (2009)


Wet Retention Pond• Permanent pool of water for removing pollutants • Additional capacity above permanent pool for detaining runoff

Forebay Main pond

Vegetated Side

Outlet Structure

Permanent pool elevation

Temporary pool elevation

Forebay berm

Vegetated Shelf


Typical Wet Pond


Wet Retention Pond

Sedimentation

Adsorption Plant Uptake

Dilution


Regulatory Credits• Pollutant Removal

- 85% Total Suspended Solids- 25% Total Nitrogen- 40% Total Phosphorous

• Water Quantity- Peak runoff attenuation- No runoff volume reduction


Wet Ponds Over Hydrologic Soil Group A

• Requires an impermeable liner to comply with state guidelines

Water

Bentonite/clay liner

Permeable Soil


Regions of North Carolina


Infiltrating Wet Pond


Objectives• Quantify the effects of infiltration on wet

pond hydrology• Assess the water quality performance of

wet ponds that infiltrate• Determine if infiltrating wet ponds are

acceptable practices, and if so, develop supplemental design guidance and plant selection


Sites

Bingham Station


Sites

Bingham Station


SitesBingham pond Raeford pond

Date construction was completed Mar-11 Jun-12

Surface area at permanent pool (ha) 0.12 0.08

Underlying Soil/HSG Autryville loamy sand/A Candor sand/A

Drainage Area (ha) 2.37 1.94Impervious Area (ha) 1.82 0.85

% Impervious 77 44Loading Ratio (area) 20:1 24:1Depth to SHWT (m) >1 <1Temp. water quality ponding depth (m) 0.45 0.9


Bingham Station

Raeford Crossing Apartments

Inlet

Outlet

Inlet 1

Outlet

Inlet 2

Images from Google Earth


Methods• Influent/Effluent Flow Rates

and Volumes - ISCO 6712 Automated samplers with Area Velocity Meter or compound weirs

• Rainfall and Intensity –manual and tipping bucket rain gauge

• Evaporation - ET gage atmometer model E with #30 turfgrass reference ET cover (Allen et al., 1998)

• Storage Volume - Hobo U20 - water level logger


Water Budget

= Vf

Vi = Initial volumeVin = Inflow volumeP = Rainfall on pondVOut = Outflow volumeE = EvaporationF = InfiltrationVf = Final volume


Water Quality

• Flow-proportional, composite samples using ISCO samplers

• Nutrients (TKN, TAN, NOx, TN, OrthoP, and TP) and Total Suspended Solids (TSS)


Results

Bingham RaefordNumber of water quality events 23 20Minimum storm rainfall (mm) 4 5Maximum storm rainfall (mm) 76 102

Minimum - 5-min peak rainfall intensity (mm/hr) 3 7Maximum - 5-min peak rainfall intensity (mm/hr) 135 133

Bingham RaefordNumber of hydrologic events 77 66Minimum storm rainfall (mm) 3 3Maximum storm rainfall (mm) 102 102


PrecipitationMonth

30-yr Normal* Bingham Raeford

Jan 106 117 114Feb 87 47 53Mar 111 117 138Apr 78 156 176May 84 57 64

Jun** 106 300 115Jul** 132 187 44Aug 132 117 118Sep 121 37 28Oct 77 13 19Nov 72 69 65Dec 81 115 132Year 1186 1330 1067

*(State Climate Office of North Carolina, 2014)**Rainfall totals at Bingham site from 2013 and rainfall totals from Raeford site from 2014


44 mm Event - Bingham0

0.5

1

1.5

2

2.5

3

3.5

40

0.02

0.04

0.06

0.08

0.1

0.12

0.14

11/26/13 8:24 11/26/13 18:00 11/27/13 3:36 11/27/13 13:12 11/27/13 22:48 11/28/13 8:24

Rai

nfal

l (m

m)

Flow

rate

(m3 /s

)

Influent Effluent Rainfall

83% Volume Reduction


Volume Reduction - Bingham0

100

200

300

400

5000

20

40

60

80

100

120

Rai

nfal

l (m

m)

Volu

me

Red

uctio

n (%

)

Volume Reduction Rainfall


Bingham Water Budget

MonthRainfall (mm)

Initial WL (m)

Influent Vol (m3)

Effluent Vol (m3)

Evap (m3)

Final WL (m)

InfiltratVol (m3)

Vol Reduction

(%)June 300 -0.16 3989 2075 123 0.19 1734 48.0July 187 0.19 2989 2683 158 -0.03 655 10.3

August 117 -0.03 1526 540 154 -0.19 1143 64.6September 37 -0.19 446 0 132 -0.19 359 100.0

October 13 -0.19 211 0 80 -0.43 380 100.0November 69 -0.43 805 84 67 -0.12 437 89.6December 115 -0.12 1414 423 47 -0.03 981 70.1January 117 -0.03 1751 872 55 -0.14 1137 50.2February 47 -0.14 751 4 62 -0.19 865 99.5

March 117 -0.19 2448 720 101 0.03 1619 70.6April 156 0.03 2428 1056 156 0.24 1290 56.5May 57 0.24 1099 441 170 -0.36 1417 59.8


Volume Reductions - Raeford0

50

100

150

200

250

300

350-20

0

20

40

60

80

100

120

Rai

nfal

l (m

m)

Volu

me

Red

uctio

n (%

)

Volume Reduction Rainfall


Raeford Water Budget

MonthRainfall (mm)

Initial WL (m)

Influent Vol (m3)

Effluent Vol (m3)

Evap(m3)

Final WL (m)

InfiltratVol (m3)

Vol Reduction

(%)August 118 0 1765 950 99 -0.03 655 46.2

September 28 -0.03 403 54 85 -0.15 566 86.7October 19 -0.15 77 0 52 -0.49 337 100.0

November 65 -0.49 684 64 43 -0.01 673 90.6December 132 -0.01 1855 1091 31 0.25 902 41.2January 114 0.25 1581 1816 36 -0.20 526 -14.9

February 53 -0.20 390 164 40 -0.11 592 58.1March 138 -0.11 1654 881 65 0.16 820 46.7April 176 0.16 2303 1665 100 0.61 1287 27.7May 64 0.61 1296 1107 109 -0.28 471 14.6June 115 -0.28 1582 723 81 0.01 687 54.3July 44 0.01 343 42 105 -0.31 451 87.7


Fate of Runoff - Bingham01002003004005006007008009000

1000

2000

3000

4000

5000

6000

Rai

nfal

l (m

m)

Volu

me

(m3 )

Outflow Infiltration Evaporation Rainfall


Fate of Runoff - Raeford0

100

200

300

400

5000

1000

2000

3000

4000

5000

Rai

nfal

l (m

m)

Volu

me

(m3 )

Outflow Infiltration Evaporation Rainfall


Fate of Runoff

40%

6%

54%

Bingham PondOutflow Evaporation Infiltration

49%

5%

46%

Raeford PondOutflow Evaporation Infiltration


Fate of Runoff

40% 49%

54%46%

6%5%

0

5000

10000

15000

20000

25000

Bingham Raeford

Tota

l inf

low

(m3 )

EvaporationInfiltrationOutflow


Summary of Hydrology

Bingham RaefordMedian Peak Flow Reduction* 99.2% 98.7%Median Volume Reduction** 100.0% 100.0%

Median Antecedent Dry Period (days) 2.4 3.9

*Values include storm events with no outflow that have a volume reduction and peak flow rate reduction of 100%.** Only solo storms (Bingham n=52, Raeford n=40) – solo storms considered those that began when the stage was below the draw-down orifice and the pond had time to de-water prior to the following event


0

1

2

3

4

5

60

1

2

3

4

5

6

7

8/19/2013 0:00 8/20/2013 0:00 8/21/2013 0:00

Rai

nfal

l (m

m)

Flow

Rat

e (c

fs)

Influent Effluent Rainfall

Bingham - 49 mm Event

-97% Peak Flow Reduction-53% Volume Reduction


Bingham Site

Date Rain (mm)

Peak Flow Reduction

(%)

Volume Reduction

(%)

08/19/13 49 98 53

11/26/13 42 99+ 83

04/29/14 76 99+ -

05/15/14 57 99 68


Raeford Site

Date Rain (mm)

Peak Flow Reduction

(%)

Volume Reduction

(%)

12/14/13 40 98 31

12/29/13 50 70 -

03/16/14 46 93 34

03/28/14 34 99 -


Draw down curves post storm event

0

0.2

0.4

0.6

0.8

5/16/14 5/17/14 5/18/14 5/19/14 5/20/14 5/21/14

Wat

er L

evel

(m)

Bingham Raeford

Bingham pond – 2.38 days Raeford pond – 4.81 days


Average Water Level

-0.35-0.3

-0.25-0.2

-0.15-0.1

-0.050

0.050.1

0.15

Wat

er L

evel

(m)

Month

BinghamRaeford


Volume Reduction

0

10

20

30

40

50

60

70

80

90

100

Volume Re

duction (%

)

Month

Bingham Raeford


Bingham Water Level

‐0.4

‐0.35

‐0.3

‐0.25

‐0.2

‐0.15

‐0.1

‐0.05

018‐Oct 19‐Oct 20‐Oct 21‐Oct 22‐Oct 23‐Oct 24‐Oct 25‐Oct 26‐Oct 27‐Oct 28‐Oct

Stage Re

lativ

e to Drawdo

wn Orifice (m

)

Date


Bingham Water Level

‐0.4

‐0.35

‐0.3

‐0.25

‐0.2

‐0.15

‐0.1

‐0.05


Stage Re

lativ

e to Drawdo

wn Orifice (m

)

Date


Bingham Water Level

y = ‐0.0134x + 557.12R² = 0.994

‐0.4

‐0.35

‐0.3

‐0.25

‐0.2

‐0.15

‐0.1

‐0.05


Stage Re

lativ

e to Drawdo

wn Orifice (m

)

Date


Bingham Infiltration Rate (October)

0.013 m/day 0.56 mm/hrInfiltrated Volume = 390 m3

Surface Area of pond = 1212 m2

Number of Days = 310.010 m/day 0.43 mm/hr

Evaporation = 6.3 cmNumber of days = 31 days

0.002 m/day 0.09 mm/hr


Raeford Water Level

y = ‐0.0138x + 571.72R² = 0.9914

‐0.6

‐0.5

‐0.4

‐0.3

‐0.2

‐0.1

017‐Oct 19‐Oct 21‐Oct 23‐Oct 25‐Oct 27‐Oct 29‐Oct 31‐Oct 2‐Nov 4‐Nov

Water Level (m

)

Date


Median Nutrient Concentrations ‐ Raeford

0

0.2

0.4

0.6

0.8

1

1.2

1.4

TKN NO3+NO2 TN TAN OP TP

Med

ian Nutrie

nt Con

centratio

ns (m

g/L)

Influent Effluent

0

5

10

15

20

25

30

35

40

45

50

TSS

n=11n=9


Median Nutrient Concentrations ‐ Bingham

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

TKN NO3+NO2 TN TAN OP TP

Med

ian Nutrie

nt Con

centratio

ns (m

g/L)

Influent Effluent

0

5

10

15

20

25

30

35

40

45

50

TSS

n=20n=17


Median Concentration Reductions

‐20

0

20

40

60

80

100

TKN NO3+NO2 TN TAN OP TP TSS

Concentration Re

duction (%

)

Bingham Raeford

n=17n=9


Water Quality


Water Quality


Bingham WQ ConcentrationsMedian Values

VariableInlet

(mg/L)Outlet (mg/L)

Percent median conc. reduction (%)

TKN 0.55 0.55 -1NO2,3 0.19 0.05 71*TN 0.74 0.57 24

TAN 0.16 0.04 74*ON 0.42 0.54 -27*OP 0.008 0.003 65*PBP 0.049 0.051 -5TP 0.06 0.05 9*

TSS 44 12 74*(n=23 inlet, n=19 outlet, n=22 inlet TSS, n=18 outlet TSS)*Significant difference between inlet and outlet at α=0.05 sig level


Raeford WQ Concentrations

(n=20 inlet, n=16 outlet)*Significant difference between inlet and outlet at α=0.05 sig level

Median Values

VariableInlet

(mg/L)Outlet (mg/L)

Percent median conc. reduction (%)

TKN 1.00 0.72 28NO2,3 0.24 0.10 58*TN 1.26 0.79 37*

TAN 0.23 0.08 65*ON 0.74 0.63 15OP 0.064 0.027 58*PBP 0.12 0.10 15TP 0.23 0.13 42*

TSS 50 14 73*


0.00.10.20.30.40.50.60.70.80.9

TKN NOx TN TAN OP TP

Med

ian

Efflu

ent C

once

ntra

toin

s (m

g/L)

Bingham Raeford DOT Museum

Median Effluent Concentrations

Winston, R. J., Hunt, W. F., Kennedy, S. G., Merriman, L. S., Chandler, J., & Brown, D. (2013). Evaluation of floating treatment wetlands as retrofits to existing stormwater retention ponds.Ecological Engineering, 54(0), 254-265.

0

5

10

15

20

25

30

TSS




0.00.10.20.30.40.50.60.70.80.9

TKN NOx TN TAN

Med

ian

Efflu

ent C

onc.

(mg/

L)





0

2

4

6

8

10

12

14

16

TSS0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

OP TP

Med

ian

Efflu

ent C

onc.

(mg/

L)



Mean Effluent Concentrations

0.00.10.20.30.40.50.60.70.80.91.0

TKN TN TAN

Mea

n Ef

fluen

t Con

c. (m

g/L)

Bingham RaefordAnn McCrary Silver StreamEcho Farms Golf Course LakesideWaterford Runaway Bay

(Mallin et al., 2002) and (Wu et al., 1996)


Mean Effluent Concentrations

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

OP TP

Mea

n Ef

fluen

t Con

c. (m

g/L)

Bingham RaefordPond A Pond CAnn McCrary Silver StreamEcho Farms Golf Course LakesideWaterford Runaway Bay

05

101520253035404550

TSS

(Comings et al., 2000), (Mallin et al., 2002) and (Wu et al., 1996)


Bingham Load Reductions

Nutrients n=19, TSS n=17 -only the storms with both inflow and outflow sampled* Significant difference between inlet and outlet at α=0.05 sig level on a storm-by-storm basis

Variable∑ Inlet Loading

(kg)∑ Outlet Loading

(kg)Percent

Reduction (%)TKN 4.1 2.2 45*

NO2,3 1.1 0.4 68*TN 5.2 2.6 50*

TAN 1.1 0.3 70*ON 3.0 1.9 37*OP 0.05 0.02 62*PBP 0.5 0.2 60*TP 0.6 0.2 61*

TSS 451 66 85*


Raeford Load Reductions

n=16 only the storms with both inflow and outflow sampled* Significant difference between inlet and outlet at α=0.05 sig level on a storm-by-storm basis

Variable∑ Inlet Loading

(kg)∑ Outlet

Loading (kg)Percent Reduction

(%)TKN 7.3 4.0 45*

NO2,3 1.7 0.7 57*TN 9.0 4.8 47*

TAN 1.6 0.6 62*ON 5.7 3.4 40*OP 0.7 0.2 68*PBP 1.0 0.6 41*TP 1.6 0.8 49*

TSS 504 167 67*


Bingham Yearly Loadings

Variable

Annual Influent loading (kg/yr)

Annual Effluent loading (kg/yr)

Annual Influentloading

(kg/ha/yr)

Annual Effluent loading

(kg/ha/yr)

Percent Reduction

(%)

NC undeveloped*

(kg/ha/yr)TKN 11.1 4.8 4.7 2.0 57 5.3NO2,3 2.8 0.8 1.2 0.3 74 1.0TN 13.9 5.5 5.9 2.3 60 6.3

TAN 2.9 0.7 1.2 0.3 77 0.2ON 8.2 4.1 3.5 1.7 50 -OP 0.2 0.04 0.07 0.02 74 -TP 1.5 0.5 0.6 0.2 68 0.5

TSS 1109 141 469 60 87 349

*(Line & White, 2007)


Raeford Yearly Loadings

*(Line & White, 2007)

Variable

Annual Influent loading (kg/yr)

Annual Effluent loading (kg/yr)

Annual Influent loading

(kg/ha/yr)

Annual Effluent loading

(kg/ha/yr)

Percent Reduction

(%)

NC undeveloped*

(kg/ha/yr)TKN 14.5 7.9 7.5 4.1 46 5.3NO2,3 3.3 1.4 1.7 0.7 58 1.0TN 17.8 9.3 9.2 4.8 48 6.3

TAN 3.3 1.2 1.7 0.6 62 0.2ON 11.4 6.7 5.9 3.4 42 -OP 1.3 0.4 0.7 0.2 68 -TP 3.1 1.6 1.6 0.8 49 0.5

TSS 981 325 506 168 67 349


Inlet

Forebay

Basin

OutletBerm

LinedUn-lined


Inlet

Forebay Basin

OutletBerm

Restrict or Allow Infiltration


0

5000

10000

15000

20000

25000

Bingham Raeford

Out

flow

Vol

ume

(m3 )

Location

Infiltration Allowed Infiltration Restricted

Restrict or Allow Infiltration?

135% 93%


Inlet

Forebay

Basin

OutletBerm

LinedUn-lined

Research Implications


BMP Manual Errata Sheet


Plant Selection for Infiltrating Wet Ponds

http://greasebustersandsteam.com/Grease_Busters_%26_Steam_Inc/Coming_Soon.html


Conclusions• Substantial volume reductions when unlined

and located over hydrologic group A soils• Both ponds able to reduce peak flows from

small and large events • With both reduced EMCs and volume

reductions, nutrient and TSS loading were significantly reduced

• Effluent EMCs appear to be on par with other non-infiltrating wet ponds.


Next Steps• Complete one year of monitoring at each pond

• Statistical analysis• Design guidelines for purpose‐built infiltrating wet ponds

• Plant selection recommendations• Assign pollutant removal credits to infiltrating wet ponds


Acknowledgements

• Dr. Bill Hunt• Ryan Winston• Shawn Kennedy• City of Fayetteville (Giselle Rodriguez)• Home Builders Association of Fayetteville• Linda McKenzie and Jenny James, Center for

Applied Aquatic Ecology


More information

Joshua [email protected]

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