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Vegetative filter strips for controlling feedlot runoff pollution in North Dakota
Atikur Rahman PhD Candidate
Ag. and Biosystems Engineering, NDSU 7 February, 2013
WRRI Fellowship Research Presentations NDWQMC Meeting, Fargo
Introduction • One of the major sources of water pollution is
agricultural production practices
• Water pollution due to eutrophication caused by the excessive P in the water bodies
• Animal industry accounts for 16% water impairment from agricultural production (USEPA, 2001)
In North Dakota • Almost 90% of the state’s land is occupied by
farms and ranches • Cattle 1.7 m, Pigs 1.6 m, and Sheep 0.88 m heads • As published by NDDoH, 2012, nutrients loading
from • erosion & runoff from cropland, • hydrologic modification and • runoff from animal feeding operations
Introduction (Contd.)
• Significant portion of the state’s surface water is
either threatened or does not support the aquatic life use due to excessive nutrient loadings
• BMPs must be developed to prevent water quality degradation
Introduction (Contd.)
• Containment structures are commonly used • Disadvantages are:
– expensive – occupies large area – requires regular maintenance, and – risks groundwater pollution Alternative practice is needed
Introduction (Contd.)
• Vegetative filter strips (VFS) is an alternative to containment structure
• Depending on the geographical region, VFS design criteria varied significantly
• VFS performance needs to be evaluated based on local and regional climatic condition and design criteria
Vegetative Filter Strips (VFS)
Objectives
• To evaluate the performance of vegetative filter strips installed at the down-slope end of feedlots under North Dakota climatic and management practices
Layout of VFS system
FeedlotBuffer strip
Settling basin
FeedlotGrass area
Retaining pond
Solids separator
Buffer strip
Sampling points
Instrumentation • Inflow (before entering into buffer) and outflow (after leaving buffer) • With bucket and float arrangement
• ISCO 6712
Runoff samples - Nutrients
- Total phosphorus (TP) and ortho-phosphorus (OP) - Total Kjeldahl nitrogen (TKN), nitrate-nitrogen (NO3-
N), and ammonium nitrogen (NH4-N) - Potassium (K)
- Solids - Total solids (TS) - Total suspended solids (TSS)
- pH - Electrical conductivity (EC)
Sample Analysis
• Paired ‘t’ test performed to compare mean pollutant concentrations between inflow and out flow of VFS
• The null hypothesis tested was that mean pollutant concentrations between inflow and out flow of VFS were same
• All statistical analyses were performed in the SAS 9.2
Statistical Analysis
TSS concentration trend- Cass County
0
20
40
60
80
100
120
140
1600
500
1000
1500
2000
2500
3000
350025
-Jul
1-Au
g
2-Au
g
12-A
ug
10-O
ct
18-A
pr
23-A
pr
23-M
ay
29-M
ay
11-Ju
n
13-Ju
n
20-Ju
n
25-Ju
l
8-Au
g
2011 2012
Rain
fall,
mm
TSS
conc
entr
atio
n, m
g/L
Sampling dates
Inflow Outflow Rainfall
0
20
40
60
80
100
1200
500
1000
1500
2000
2500
14-Jul 2-Aug 15-Aug 29-May 14-Jun 20-Jun 26-Jul
2011 2012
Rain
fall,
mm
TSS
conc
entr
atio
n, m
g/L
Sampling dates
Inflow Outflow Rainfall
TSS concentration trend- Sargent County
0
20
40
60
80
100
120
1400
500
1000
1500
2000
2500
3000
3500
4000
4500
Rain
fall,
mm
Tota
l sus
pend
ed s
olid
s, m
g/L
Sampling date
Inflow Outflow Rainfall
TSS conc. trend- Richland County
0
20
40
60
80
100
120
140
1600
50
100
150
200
25025
-Jul
1-Au
g
2-Au
g
12-A
ug
10-O
ct
18-A
pr
23-A
pr
23-M
ay
29-M
ay
11-Ju
n
13-Ju
n
20-Ju
n
25-Ju
l
8-Au
g
2011 2012
Rain
fall,
mm
TP c
once
ntra
tion,
mg/
L
Sampling dates
Inflow Outflow Rainfall
TP concentration trend- Cass County
0
20
40
60
80
100
120
1400
20
40
60
80
100
120
140
160
180
14-Jul 2-Aug 15-Aug 29-May 14-Jun 20-Jun 26-Jul
2011 2012
Rain
fall,
mm
TP c
once
ntra
tion,
mg/
L
Sampling dates
Inflow Outflow Rainfall
TP concentration trend- Sargent County
0
20
40
60
80
100
1200
10
20
30
40
50
60
Rain
fall,
mm
TP c
once
ntra
tion,
mg/
L
Sampling date
Inflow Outflow Rainfall
TP conc. trend- Richland County
0
20
40
60
80
100
120
140
1600
50
100
150
200
250
30025
-Jul
1-Au
g
2-Au
g
12-A
ug
10-O
ct
18-A
pr
23-A
pr
23-M
ay
29-M
ay
11-Ju
n
13-Ju
n
20-Ju
n
25-Ju
l
8-Au
g
2011 2012
Rain
fall,
mm
TKN
/TN
con
cent
ratio
n, m
g/L
Sampling dates
Inflow Outflow Rainfall
TKN/TN conc. trend- Cass County
0
20
40
60
80
100
1200
20
40
60
80
100
120
140
160
180
200
14-Jul 2-Aug 15-Aug 29-May 14-Jun 20-Jun 26-Jul
2011 2012
Rain
fall,
mm
TKN
/TN
con
cent
ratio
n, m
g/L
Sampling dates
Inflow Outflow Rainfall
TKN/TN concentration trend- Sargent County
At Richland County
0
20
40
60
80
100
1200
50
100
150
200
250
300
Rain
fall,
mm
TKN
con
cent
ratio
n, m
g/L
Sampling date
Inflow Outflow Rainfall
TKN conc. trend- Richland County
VFS Performance at Cass County
-700
-600
-500
-400
-300
-200
-100
0
100
200
EC TS TSS Ortho-P TP NH4-N NO3-N TKN/TN K
%Re
duct
ion
of c
once
ntra
tion
Pollutants
2011 2012
VFS Performance at Sargent County
-150
-100
-50
0
50
100
EC TS TSS Ortho-P TP NH4-N NO3-N TKN/TN K
%Re
duct
ion
of c
once
ntra
Pollutants
2011 2012
VFS Performance at Richland County
0
10
20
30
40
50
60
70
80
TS TSS Ortho-P TP NH4-N TKN/TN K
%Re
duct
ion
of c
once
ntra
tion
Pollutant
2010
Overall • Vegetative filter strip was effective for sediment
and sediment bound pollutant reduction
• Soluble pollutants were not effectively removed
• Cass County feedlot with longer flow length (65 m), dense broadleaf cattail grass filter bed outperformed the Sargent and Richland Counties
Acknowledgements • NDDoH (EPA 319 grants) • ND-WRRI • Sargent County Feedlot • Richland County Feedlot • Cass County Feedlot
Feedlot Description Features Parameters Cass County (CC)
feedlots Sargent County (SC) feedlots Richland County
(RC) feedlots Climate Annual average
rainfall, mm 494 494 468
Feedlot
Length, m 50 76 Width, m 115 62
Soil texture Clay Fine sandy loam Sandy loam
Number of pens 6 8 2 Designed animal
capacity 200 180 - 200 250
VFS
Flow-length, m 65 40 12 Soil texture Clay Fine sandy loam Sandy loam
Vegetation type Common cattails garrison creeping foxtail and reed canarygrass
Mixed
Slope, % 2 3 2
Runoff
Runoff distribution Direct overland flow Channelized flow with a solids separator
Direct overland flow
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