Developing a Framework to Advance Statewide Phosphorus...
8
11/25/2019 1 Developing a Framework to Advance Statewide Phosphorus Reduction Credits for Leaf Collection 2. Develop criteria to rapidly assess effectiveness of different leaf collection practices using field survey techniques 3. Advance ability to model P load in urban watersheds and response to management Study Objectives 1. Collect water‐quality samples from a control and test basin to determine if removing leaves will result in detectable changes in phosphorus [“book end approach”] All Leaves Stay All Leaves Gone
Transcript of Developing a Framework to Advance Statewide Phosphorus...
11/25/2019
1
Developing a Framework to Advance Statewide Phosphorus Reduction Credits for Leaf Collection
2. Develop criteria to rapidlyassess effectiveness of differentleaf collection practices usingfield survey techniques
3. Advance ability to modelP load in urban watersheds and response to management
Study Objectives
1. Collect water‐quality samples from a control and test basin to determine if removing leaves will result in detectablechanges in phosphorus [“book end approach”]
All
Leav
es S
tay
All
Leav
es G
one
11/25/2019
2
Study Basin
Source Area Control Test
Area (acres) 15.9 3.0
Streets 17% 19%
Driveways 6% 4%
Roofs 17% 19%
Sidewalks 5% 3%
Lawns/Open 55% 54%
Other Impervious <1% 0%
Tree Cover 45% 68%
Control Test
USGS Monitoring Location
Paired Basin Study Design
0
0.5
1
1.5
2
2.5
3
3.5
April May June July August September October November
Mean
Total P
hosphorus Concentration, in m
g/l
Mean total phosphorus concentration during the calibration period in which there wasno leaf collection or street cleaning
Control (2013‐2015)
Test (2013‐2014)
April May June-Aug Sept Oct Nov
Photo Credit: USGS
11/25/2019
3
“Escalated” Leaf Management
In addition to municipal efforts, USGS field crews would clear all organic debris from street surface prior to rain event
Photo Credit: USGSPhoto Credit: USGS
0
0.5
1
1.5
2
2.5
3
3.5
April May June July August September October NovemberMean
Total P
hosphorus Concentration, in m
g/l
Mean total phosphorus concentration during the calibration period compared to the treatment period in which there was weekly leaf collection and/or street cleaning
Control (2013‐2015)
Test (2013‐2014)
Test (Treatment 2015)
Photo Credit: USGS
11/25/2019
4
Leaf Management Practices
Variables that influence nutrient load:
Photo Credit: USGSPhoto Credit: USGS
• leaf collection method • street cleaning technology • frequency
Matrix of Leaf Collection and Street Cleaning Methods, and Frequency
HIGH TREE CANOPY
Leaf Collection Street Cleaning
Method Frequency Method Frequency Year Completed Title
Transfer Weekly Mechanical/blower Pre‐event 2015 Upper Maximal
Transfer 3‐4x Mechanical 3‐4x 2016 SOP
Transfer 3‐4x Regenerative Air Weekly 2017 SOP+
Vacuum Weekly Regenerative Air Weekly 2017 Vacuum Mulch
Transfer 3‐4x None ‐‐ 2018 Leaf piles only
Vacuum 3‐4x Regenerative Air weekly 2018 SOP+
MEDIUM TREE CANOPY
Leaf Collection Street Cleaning
Method Frequency Method Frequency Year Completed Title
Transfer 3‐4x Mechanical 3‐4x 2018 SOP
Vacuum Weekly Mechanical Weekly 2019 Vacuum Mulch
Vacuum Weekly Regenerative Air Weekly 2019 Leaf piles only
Preliminary Information – Subject to Revision. Not for Citation or Distribution
11/25/2019
5
0
10
20
30
40
50
60
70
80
90
Max 2017 Vac 2017SOP+
2018SOP+
2016SOP (HC)
2018Pilesonly
2018SOP(MC)
Percen
t Red
uction
Total Phosphorus
0
10
20
30
40
50
60
70
80
90
Max 2017 Vac 2017SOP+
2018SOP+
2016SOP (HC)
2018Pilesonly
2018SOP(MC)
Percen
t Red
uction
Dissolved Phosphorus
Change in Phosphorus Load Measured in Stormwater Runoff
Not
sta
tistic
ally
sig
nific
ant
Not
sta
tistic
ally
sig
nific
ant
Not
sta
tistic
ally
sig
nific
ant
95% Significance
90% Significance
85% Significance
80% Significance
Preliminary Information – Subject to Revision. Not for Citation or Distribution
Statewide Phosphorus Reduction Credits
Madison SOP = 3-4 times/season
11/25/2019
6
Developing framework to predict end‐of‐pipe phosphorus load
CategoryAverage Net Weight, lbs.
(80 ft frontage)
Lbs. of Leaves Per
Foot of curb
1 5 0.05
2 10 0.13
3 16 0.20
4 25 0.35
1
2
3
4Preliminary Information – Subject to Revision. Not for Citation or Distribution
Estimating phosphorus load from leaf mass on streets
Estimating Leachable Phosphorus in Leaves
0
100
200
300
400
500
600
700
0 50,000 100,000 150,000 200,000 250,000 300,000 350,000
Measured TDP (g) ‐Adjusted
Estimated Leaf Mass (g)
Study Site #2
0
20
40
60
80
100
120
140
0 50000 100000 150000 200000 250000
Measured TDP (g) ‐Adjusted
Estimated Leaf Mass (g)
Study Site #1
Preliminary Information – Subject to Revision. Not for Citation or Distribution
11/25/2019
7
Phosphorus Leaching Experiments
• Whole vs crushed leaves
• New vs old leaves
• Incubation temperature
• 20 vs 4 degrees C
Source: Yi Wang, University of Wisconsin - Madison
1
= TDP conc (mg/g-1)
= max. TDP conc. (mg/g-1)
= first order rate constant
= time
Estimate of TDP at Study Site
Preliminary Information – Subject to Revision. Not for Citation or Distribution
0
20
40
60
80
100
120
140
160
0 50000 100000 150000 200000 250000
Measured TDP (g) ‐Adjusted
Estimated Leaf Mass (g)
Measured
Predicted
11/25/2019
8
Next Steps…
• Evaluate the importance of collecting leaf piles – are clean streets more important?
• Evaluate influence of canopy ‐ medium vs. high
• Continue to develop ability to predict contributions of phosphorus in stormwater from leaf litter• WinSLAMM
• i‐Tree Species
Photo Credit: USGS
