1. MinnFARM Feedlot Runoff Compliance and Priority

2. 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

3. 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

4. Key Reference Documents
MinnFARM Users Guide:
Evaluating Open Lot Runoff Compliance, MPCA, May 1,

5. 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

6. 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)

7. 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

8. 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)
Area 3 – Clean water flowing onto the buffer area
Buffer – Vegetated treatment area for feedlot runoff
End of Treatment (EoT)
Related to FLEval Point of Discharge
Water of Concern (WoC)
Receiving waters for feedlot runoff not considered in FLEval

9. Drainage Ditch, Wetland,
Buffer
“Area 2”
Feedlot
EoT
-Property Boundary
-Road Ditch
-Intermittent Stream
-Water of Concern
WoC = Lake, Stream,
Drainage Ditch, Wetland,
Tile Intake, Sinkhole
Area 3
MinnFARM Schematic

10. 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

11. 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

12. 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

13. 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

14. 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

15. BOD Load Limit

16. P Load Limit

17. 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)

18. 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

19. 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

20. 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 compliance
indication

21. Example MinnFARM INDEX
1 acre lot with 100 AU, no buffer

22. Example MinnFARM INDEX
1 acre lot with 100 AU, 100 ft. good buffer, 30 ft. width

23. 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

24. 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 ( )
Require buffer size to be at least as large as for type “B” soils

25. 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

26. 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

27. 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

28. 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

29. END