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MinnFARM Feedlot Runoff

Compliance and Priority

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Credits (and who to blame?)

Base presentation prepared by MPCA for MPCA and County feedlot staff

Revised by Al Kean, BWSR, for SWCD and BWSR staff

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Topics Bit of history about FLEval Brief overview of MinnFARM (Minnesota

Feedlot Annualized Runoff Model) Annual feedlot runoff Load Limits to define

compliance with State water quality standards

MinnFARM Priority INDEX to define noncompliant feedlot priority for financial and technical assistance

Feedlot regulator Best Professional Judgment (BPJ) considerations

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Key Reference Documents

MinnFARM Users Guide: http://www.manure.umn.edu/applied/assets/MinnFARM%20Users%20Guide%202_0%20051508.pdf

Evaluating Open Lot Runoff Compliance, MPCA, May 1, 2008 http://www.pca.state.mn.us/publications/wq-f8-35.pdf

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FLEval Purpose and Approach

1980 – approximately 90,000 feedlots in MN 1982 – ARS – Create consistent, scientific tool to

prioritize feedlots for environmental upgrades Approach – compute BOD concentration at Point

of Discharge for 25-yr., 24-hr. runoff event, which related to MN water quality standards at the time

Rating from 0 to 100, with 0 = 25 mg/l BOD at Point of Disharge for 25-yr., 24-hr. event

2002 – DOS version converted to Excel

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MinnFARM Purpose and Approach

FLEval is single event based, does not consider all seasons or all runoff events

2004 – EPA 319 grant to UMN to develop annualized feedlot runoff model (using Excel)

Evaluates 4 seasons of year using rainfall and snow data from nearest weather station

Computes annual loads of COD, P, N, BOD and fecal coliform at End of Treatment

Priority INDEX considers annual loads and receiving waters (1 to 100, low to high priority)

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MinnFARM Other Changes from FLEval

Updated research Accounts for varying number of animals on the

lot at different times of the year Incorporates width of buffer in calculations Can integrate compliance indication for multiple

lots in one feedlot operation Designated Storm worksheet can evaluate

specific storm events MinnFARM FLEval output removed

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MinnFARM vs. FLEval Terms Feedlot – Area where animals are kept

Same as FLEval Area 2 – Area that produces clean water flowing through

the feedlot (yard water) Same as FLEval

Area 3 – Clean water flowing onto the buffer area Same as FLEval

Buffer – Vegetated treatment area for feedlot runoff Same as FLEval

End of Treatment (EoT) Related to FLEval Point of Discharge

Water of Concern (WoC) Receiving waters for feedlot runoff not considered in FLEval

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Buffer

“Area 2”

FeedlotEoT -Property Boundary -Road Ditch -Intermittent Stream -Water of Concern

WoC = Lake, Stream, Drainage Ditch, Wetland,

Tile Intake, Sinkhole

Area 3

MinnFARM Schematic

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End of Treatment (EoT)

Point at which the runoff leaves the treatment area and: Enters a road ditch, Enters a intermittent stream, Crosses a property boundary

(unless written agreement

with neighbor) Enters a Water of Concern

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Water of Concern (WoC)

Receiving water for feedlot runoff (affects MinnFARM Compliance Indication and Priority Index) Lakes (>25 acres of open water) Perennial Stream w/wo lake Drainage Ditch w/wo lake Tile Intake w/wo lake Public or Non-public Wetlands Sinkhole or other direct conduit

to Groundwater

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Key Factors in MinnFARM Lot Size

Reduce lot size and amount of runoff to allow for more treatment with less buffer

Soil Types Model is greatly influenced by infiltration

Only ½ of BOD can be settled out Area 2 and Roof Runoff

Reduce amount of runoff through the feedlot and increase effects of buffer treatment

Buffer Width Substantial effects on buffer treatment

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Evaluating Open Lot Runoff Compliance (using MinnFARM)

MPCA document number: wq-f8-35 Effective May 1, 2008 Minnesota requirements for open feedlots

not required to have an NPDES permit Annual BOD and P Load Limits correlated

to current State water quality standards (circa 1990)

MinnFARM computes annual loads and uses load limits to indicate compliance

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Load Limits Compliance Criteria Annual Load Limits correlate to State water

quality standards: BOD standard = 25 mg/L monthly average and P standard for discharge to a lake = 1 mg/L total P monthly average

If WoC is not a lake: Annual BOD Load Limit governs: at EoT = 50 lbs. plus 0.25 lbs. per 1000 lbs. of animal weight (AU) Max. annual load 125 lbs. regardless of feedlot size

If WoC is a lake: Annual P Load Limit may govern: at EoT = 2 lbs. plus 0.01 lbs. per 1000 lbs. of animal weight (AU) Max. annual load 5 lbs. regardless of feedlot size

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40

50

60

70

80

90

100

110

120

130

0 100 200 300 400 500 600 700 800 900 1000

AU's

An

nu

al B

OD

(lb

s)

BOD Load Limit

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1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

0 100 200 300 400 500 600 700 800 900 1000

AU's

An

nu

al P

(lb

s)

P Load Limit

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Interpreting MinnFARM Results

MinnFARM is an indicator of compliance Does not guarantee compliance or non-

compliance Room for Best Professional Judgment (BPJ)

Soil types Runoff onto multiple buffers Buffer length and/or width, level spreaders, etc. Other sources of feedlot pollution (e.g. milkhouse

waste, silage leachate, animal mortality handling)

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MPCA Grandfather Policy

For existing operations previously evaluated using FLEval No need to re-evaluate with MinnFARM unless….

Feedlot has changed in a way that significantly affects modeling results

e.g. more animals, bigger lots, etc. Original design assumptions are no longer valid

e.g. clean water no longer diverted, vegetated buffer not maintained (sheet flow, vegetation)

FLEval analysis did not fit the situation very well e.g. very large operation, large runoff volumes, sensitive

features nearby

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MODEL RESULTS FOR: John Doe 1/0/00

50508

Site Summary Site Evaluation ResultsTotal Feedlot Area = 1.00 acres MinnFARM FLEval' Rating = 29

Roof Area = 0.00 acres Does Evaluation Indicate NO

Total Area 2 = 0.00 acres Regulatory Compliance? NO

Total Buffer Area = 0.07 acres

Total Area 3 = 0.00 acres Prioritization INDEX = 13

Ratio of Buffer to Feedlot Area (includes Area 2)= 0.07 Old FLEval = 27

Receiving Water SummaryThe Feedlot is NOT in a TMDL areaThe Feedlot is NOT in a Designated Water Supply Management Area

The End of Treatment is a Property BoundaryThe Water of Concern is a Tile Intake with no Lake

The name of the WoC is was not providedThe distance from the EoT to the WoC is 2000 ft

Seasonal Runoff Summary

Average Seasonal and Annual Runoff VolumeLocation (units) Spring Summer Fall Winter Annual

Feedlot Edge (acre-in) 0.78 2.72 1.04 0.67 5.21

Buffer Edge (acre-in) 0.36 0.86 0.44 0.47 2.14

Average Annual Loading from Feedlot Compliance

Parameter (units) Spring Summer Fall Winter Annual Indicator

COD (lbs) 230 550 279 302 1360Phosphorus (lbs) 4 10 5 6 26 4

Nitrogen (lbs) 13 31 16 17 76Fecal Coliform (cfu) 8.5E+13 2.0E+14 1.0E+14 1.2E+14 5.1E+14BOD 5 (lbs) 51 122 62 67 302 100 <=Using BOD Based limit

MinnFARM Version 2.0 UMN BBE

Model Outputs MinnFARM FLEval has been removed

Replaced with

Yes or No for Regulatory Compliance

INDEX – Used for prioritization ONLY

Load Limits – Used for

compliance

Which load limit is used

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MinnFARM Priority INDEX Priority Index from 1 to 100

(higher index = higher pollution potential) MinnFARM considerations include: Annual BOD and P load at EoT BOD Concentration at EoT Type of receiving water (WoC) Distance from EoT to WoC

Not used for complianceindication

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Example MinnFARM INDEX

020406080

100

0 2000 4000 6000 8000

Distance (ft)

Ind

ex

Lake

Stream/River with Lake

Stream/River no Lake

Drainage Ditch with Lake

Drainage Ditch with no Lake

Public Wetland

Non-Public Wetland

1 acre lot with 100 AU, no buffer

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Example MinnFARM INDEX

1 acre lot with 100 AU, 100 ft. good buffer, 30 ft. width

0

10

20

30

40

0 2000 4000 6000 8000

Distance (ft)

Ind

ex

Lake

Stream/River with Lake

Stream/River no Lake

Drainage Ditch with Lake

Drainage Ditch with no Lake

Public Wetland

Non-Public Wetland

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General BPJ for Compliance (Best Professional Judgment)

Four items to consider MinnFARM results very close to the thresholds No threats to human health MinnFARM index is low (<10) Long ways to waters with aquatic life or marginal

waters Farmed wetlands Type II that dry up annually

Use all four items above for decision, not just one or two. Regulator to document reasoning in the file

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Soil Type BPJ

Big influence on the model results Soil survey is not always correct Type A soils are easier to get compliance

Rapid infiltration may protect surface waters, but groundwater becomes a concern

Consider a Nitrogen balance calculation on the buffer Enough grassed area to apply at agronomic rates

Runoff analysis estimate (3 - 1 - 3)

Require buffer size to be at least as large as for type “B” soils

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Vegetated Buffer BPJ Some model runs will achieve compliance

with less than 100 feet of buffer Consider having a minimum buffer length

regardless of model results (at least 100 ft.?) Buffer width is important

Wide buffers typically develop rills No treatment after 3 inches of flow depth

Buffer vegetation type and maintenance Not all buffers should be called permanent

meadow – vegetation maintenance is critical

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Feedlot Runoff Treatment on Neighbor’s Property BPJ

MPCA recommends not counting on neighbor’s land to treat feedlot runoff Can be used if a written statement is

obtained by feedlot owner from neighbor Be aware this agreement could change at any

point, making the model invalid in the future

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Other Pollution Sources BPJ

Milkhouse waste Feed Storage and Feed Pad leachate

and/or runoff Dead Animal Treatment areas

MinnFARM model does not account for these potential pollution hazards

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Key Take-Away Information

MinnFARM is the current feedlot runoff evaluation tool

Annual BOD and P Load Limits are current compliance indication methods

MinnFARM Priority Index is a key feedlot prioritization tool

Evaluating Open Lot Runoff Compliance, May 1, 2008, wq-f8-35, is a key reference document

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END