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

Bunker Silage Storage

Loading and Compaction

Dry Weather Leachate

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

Mc Donald 1981, Referencing Bastiman 1976

Timing Leachate Production

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

Dry Weather Leachate

Dry Weather Leachate

Corrosive - Concrete Erosion

Runoff

Snowmelt Runoff

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

Impacts of Runoff

Impacts of Runoff

Rain Water Infiltration

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)

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

Collection

Collection Designs are Numerous

Collection Designs

Treatment Using Filter Strips

Does a First-Flush Exist?

Normalized COD Data - AARS

Normalized BOD5 Data

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%

% e

ven

t lo

ad

% event flow

Event Load:Flow Ratio (5%): TKN - Farm A

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%

% e

ven

t lo

ad

% 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%

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%

% e

ven

t lo

ad

% 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 (%)

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%

% e

ven

t lo

ad

% 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

Relationship of Flow vs. Concentration

Constituent Correlations

• All constituent data (TKN, TP, TS, COD, BOD) was

statistically correlated EXCEPT pH which was

negatively correlated

Total TKN Loading

0

500

1,000

1,500

2,000

2,500

Load

(lb

s)

2013 Cummulative Total Kjeldahl Nitrogen Loading: Farm A

Collected To VTA

2007 lbs

1359 lbs

Total TKN Loading

0

500

1,000

1,500

2,000

2,500

3,000

3,500

Load

(lb

s)

2014 Cummulative Total Kjeldahl Nitrogen Loading: Farm A

Collected To VTA

2235 lbs

2901 lbs

Total TKN Loading

0

50

100

150

200

250

300

350

Load

(lb

s)

2013 Cummulative Total Kjeldahl Nitrogen Loading: Farm C

Collected To VTA

60 lbs

315 lbs

Total P Loading

0

60

120

180

240

300

360

420

480

540

Load

(lb

s)

2013 Cummulative Total Phosphorus Loading: Farm A

Collected To VTA

470 lbs

317 lbs

Total P Loading

0

100

200

300

400

500

600

700

800

900

Load

(lb

s)

2014 Cummulative Total Phosphorus Loading: Farm A

Collected To VTA

687 lbs

782 lbs

Total P Loading

0

10

20

30

40

50

60

70

80

Load

(lb

s)

2013 Cummulative Total Phosphorus Loading: Farm C

Collected To VTA

10 lbs

58 lbs

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

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

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

Co

nce

ntr

atio

n (

mg/

l)

Flo

w (

gal/

min

) &

Co

nd

uct

ivit

y ((

us/

cm)/

10

)

Hours

Example Event with Conductivity: COD

Flow ConductivityMid-pt Discrete

Thank You!