The full proceedings paper is at: http://www.extension.org/72808 Silage storage is required for many livestock and poultry facilities to maintain their animals throughout the year. While feed storage is an asset which allows for year round animal production systems, they can pose negative environmental impacts due to silage leachate and runoff. Silage leachate and runoff have high levels of oxygen demand and nutrients (up to twice the strength of animal manure), as well as a low pH posing issues to surface waters when discharged. Although some research exists which shows the potency of silage leachate and runoff, little information is available to guide the design of collection, handling, and treatment facilities to minimize the impact to water quality. Detailed information to characterize the strength of the runoff through a storm is needed to develop collection systems which segregate runoff to the appropriate handling and treatment system based on the strength of the waste.

1. Bunker Silage Storage Leachate and
Runoff Management
April 2, 2015
Waste to Worth, Seattle, WA
Becky Larson, Assistant Professor and Extension Specialist,
University of Wisconsin-Madison
Aaron Wunderlin, Discovery Farms
Eric Cooley, Discovery Farms
Mike Holly, Ph.D. Student UW-Madison

2. Bunker Silage Storage

3. Loading and Compaction

4. Dry Weather Leachate

5. Leachate Production Based on
Dry Matter Content
Bastiman (1976) and Bastiman and Altman (1985) (– - - –); Sutter (1957) (– - – -); Zimmer (1974) (– – –); Haigh (1999) (—)
(Haigh, 1999)
Recommended harvest moisture
65 - 70% Corn Silage
60 - 65% Hay Silage

6. Mc Donald 1981, Referencing Bastiman 1976
Timing Leachate Production

7. Dry Weather Leachate
Constituent Leachate1
Liq. Dairy
Manure2
Dry Matter 2-10% 5%
Total N (mg/L) 1,500-4,400 2,600
P (mg/L) 300-600 1,100
K (mg/L) 3,400-5,200 2,500
pH 3.6-5.5 7.4
BOD (mg/L) 12,000-90,000 5,000-10,000
1Cornell 1994
2Clarke and Stone 1995

8. Dry Weather Leachate

9. Dry Weather Leachate

10. Corrosive - Concrete Erosion

11. Runoff

12. Snowmelt Runoff

13. Runoff Concentrations
Constituent Leachate1
Liq. Dairy
Manure2 Runoff
Dry Matter 5% (2-10%) 5% 0 - 4.6%
Total N (mg/L) 1,500-4,400 2,600 20 - 1,356
P (mg/L) 300-600 1,100 8 - 659
K (mg/L) 3,400-5,200 2,500 n/a
pH 3.6-5.5 7.4 4 - 7
BOD (mg/L) 12,000-90,000 5,000-10,000 500 - 61,210

14. Impacts of Runoff

15. Impacts of Runoff

16. Rain Water Infiltration

17. Management to Minimize Silage Storage
Runoff Constituent Concentrations
• Cover
• Top
• Maintaining face (minimize exposure)
• Cover/wrap side walls
• Cover when filling if rain is forecast (minimize water
additions)
• Clean pad (remove litter) particularly if rain event is
forecast
• Cover spoilage and litter until removal (removal can
include many options, land application, composting,
digestion, among others)

18. Silage Storage Collection System Design
Objectives
• Minimize collection volumes
• Reduce hauling requirements
• Reduce environmental impact
• Collect high strength waste for storage and land
application
• Send low strength waste to treatment systems
Current System Design
• Capture the initial volume and send to storage as it
has the highest concentrations
• This assumed a first flush scenario exists where the
first portion of the runoff has higher strength than
remaining runoff, unconfirmed
• First flush exists in urban runoff, though it would
follow this pattern

19. Collection

20. Collection Designs are Numerous

21. Collection Designs

22. Treatment Using Filter Strips

23. Does a First-Flush Exist?

24. Normalized COD Data - AARS

25. Normalized BOD5 Data

26. Normalized TKN Data – Farm A
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
%eventload
% event flow
Event Load:Flow Ratio (5%): TKN - Farm A

27. Normalized TKN Data – Farm C
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
%eventload
% event volume
Event Load:Flow Ratio (5%): Total Kjeldahl Nitrogen - Farm C
TKN - Farm C
# % # % # % # % # %
Above 2 7% 6 21% 6 21% 3 10% --- ---
W/in 29 100% 22 76% 22 76% 25 86% 29 100%
Below --- --- 1 3% 1 3% 1 3% 0 0%
Above 8 28% 10 34% 9 31% 8 28% 2 7%
W/in 21 72% 17 59% 16 55% 18 62% 26 90%
Below 0 0% 2 7% 4 14% 3 10% 1 3%
Flow (%)
10 20 50 80 90
10%
5%

28. Normalized Phosphorus Data – Farm A
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
%eventload
% event flow
Event Load:Flow Ratio (5%): TP - Farm A
TP - Farm A
# % # % # % # % # %
Above 0 0% 2 4% 0 0% 0 0% --- ---
W/in 51 100% 44 86% 33 65% 36 71% 39 76%
Below --- --- 5 10% 18 35% 15 29% 12 24%
Above 2 4% 3 6% 3 6% 0 0% 0 0%
W/in 46 90% 28 55% 23 45% 26 51% 31 61%
Below 3 6% 20 39% 25 49% 25 49% 20 39%
5%
10%
10 90805020
Flow (%)

29. Normalized Phosphorus Data – Farm C
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
%eventload
% event volume
Event Load:Flow Ratio (5%): Total Phosphorus - Farm C
TP - Farm C
# % # % # % # % # %
Above 0 0% 0 0% 2 7% 0 0% --- ---
W/in 28 100% 28 100% 26 93% 28 100% 28 100%
Below --- --- 0 0% 0 0% 0 0% 0 0%
Above 2 4% 5 10% 8 16% 3 6% 0 0%
W/in 26 93% 21 75% 17 61% 23 82% 27 96%
Below 0 0% 2 4% 3 6% 2 4% 1 2%
10%
5%
Flow (%)
10 20 50 80 90

30. Relationship of Flow vs. Concentration

31. Constituent Correlations
• All constituent data (TKN, TP, TS, COD, BOD) was
statistically correlated EXCEPT pH which was
negatively correlated

32. Total TKN Loading
0
500
1,000
1,500
2,000
2,500
Load(lbs)
2013 Cummulative Total Kjeldahl Nitrogen Loading: Farm A
Collected To VTA
2007 lbs
1359 lbs

33. Total TKN Loading
0
500
1,000
1,500
2,000
2,500
3,000
3,500
Load(lbs)
2014 Cummulative Total Kjeldahl Nitrogen Loading: Farm A
Collected To VTA
2235 lbs
2901 lbs

34. Total TKN Loading
0
50
100
150
200
250
300
350
Load(lbs)
2013 Cummulative Total Kjeldahl Nitrogen Loading: Farm C
Collected To VTA
60 lbs
315 lbs

35. Total P Loading
0
60
120
180
240
300
360
420
480
540
Load(lbs)
2013 Cummulative Total Phosphorus Loading: Farm A
Collected To VTA
470 lbs
317 lbs

36. Total P Loading
0
100
200
300
400
500
600
700
800
900
Load(lbs)
2014 Cummulative Total Phosphorus Loading: Farm A
Collected To VTA
687 lbs
782 lbs

37. Total P Loading
0
10
20
30
40
50
60
70
80
Load(lbs)
2013 Cummulative Total Phosphorus Loading: Farm C
Collected To VTA
10 lbs
58 lbs

38. Collection Design Recommendation
• First flush does not exist so collecting initial runoff does not
target collecting the greatest load per volume collected
• Recommended to collect low flows only (stop collecting
during high flows)
• If the system design to shut off during high flows is not
practical, collect low flows throughout the storm
• Additional collection of runoff within 2 weeks of filling will
increase load collection
• Grade your pad to ensure all flows enter at one central
collection point
• Check pad for cracks or other potential issues and repair
• Provide subsurface drainage to collect leachate which
permeates through the pad

39. Low Flow Collection
• Calculations show a greater loading collected
when collecting the low flow
• Low flow was calculated using 1% of the peak
flowrate from a 2-year 24-hour design storm
• Peak runoff flowrates can be calculated using
the Rational Method (although there are many
methods which you can use to do this)
• These can be calculated by hand or using
software such as HydroCAD

40. Conductivity Meter to Route High
Strength Runoff to Storage
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
0
100
200
300
400
500
600
700
800
0 4 8 12 16 20 24 28 32
Concentration(mg/l)
Flow(gal/min)&Conductivity((us/cm)/10)
Hours
Example Event with Conductivity: COD
Flow Conductivity
Mid-pt Discrete

41. Thank You!