Clarification of the Proposed ELG Request for comments (Item A.2, p 182) Alternative Groundwater Assessments
Groundwater and surface water are not separate resources
The land application of domestic sewage, manure and manure derived products is an established conservation practice
Example: Septic tank disposal fields and supplemental cropland fertilization are considered acceptable
An Infiltration rate of cm/sec from liquid manure storages is equivalent to approximately 3.15 cm per year
Assuming ammonia concentration of 500 mg/l in this infiltrating water, no denitrification losses, this is equivalent to a nitrogen application rate of 150 kg/ha. This is about 25% more than the contribution of two household septic tank systems per acre. Assuming ammonia concentration of 500 mg/l in this infiltrating water, no denitrification losses, this is equivalent to a nitrogen application rate of 150 kg/ha. This is about 25% more than the contribution of two household septic tank systems per acre.
We are aware of no evidence that lagoons or manure storage basins meeting this infiltration criteria are contributing to groundwater pollution.
The environmental cost of specifying an impermeable liner for all manure storages and lagoons is greater than the benefits
Liners fail with a sufficient frequency to obviate possible benefits
Liners can and will continue to be used in those locations in which the infiltration criteria can not be met with local resources
Seepage from lagoons and storage basins meeting the infiltration criteria is insignificant compared to the land application component of the system
Monitoring wells installed around lagoons and other manure storage basins are insensitive tools by which to monitor groundwater contamination.
Accurate measurement of downward movement on nitrogen bearing leakage requires use of a permeable wick sampler which is a research tool and not adapted to routine monitoring
Conclusion The requirement of a synthetic impermeable liner in all anaerobic lagoons and earthen storage basins is inappropriate.
Other important considerations
How do we deal with existing facilities that can not assure infiltration rates less than the criteria?
Alternate and evolving technologies have the potential to claim marketable by-products sufficiently valuable to support inter basin sales.
Extreme rainfall conditions are an infrequent cause of water quality damage based on the U.S. university representatives to the National Center Roundtable
Conclusion II The establishment of a discharge criteria more restrictive than the 25 year - 24 hour storm event will contribute significant additional cost but gain little water quality improvement. The establishment of a discharge criteria more restrictive than the 25 year - 24 hour storm event will contribute significant additional cost but gain little water quality improvement.
New technologies promise future benefits Alternating anaerobic - aerobic digestion units are producing discharge quality effluent. Alternating anaerobic - aerobic digestion units are producing discharge quality effluent. Anaerobic digesters are being built for economically driven biogas production. Anaerobic digesters are being built for economically driven biogas production. Nutritional advances allow designing better manure. Nutritional advances allow designing better manure.
New technologies promise future benefits Permeable covers that provide odor control, reduced ammonia evolution are evolving toward methane removal. Permeable covers that provide odor control, reduced ammonia evolution are evolving toward methane removal.
Special concerns of cow-calf operators Cow and calf operate as a single unit Cow and calf operate as a single unit Feeding on vegetated fields is a non- point source and should not be permitted as a point source Feeding on vegetated fields is a non- point source and should not be permitted as a point source
It is important that the definition of a CAFO retain the lack of a ground cover as part of the necessary definition, otherwise, many of the western range operations will be moved toward the permitting process with no pollution prevention benefits.
Co-permitting concerns Co-permitting would seem reasonable in situations where the animals are owned by a single or small number of owners beyond the facility owner. It does not work in the case of western feedlot operations where there may be many owners of cattle in a custom feedlot Co-permitting would seem reasonable in situations where the animals are owned by a single or small number of owners beyond the facility owner. It does not work in the case of western feedlot operations where there may be many owners of cattle in a custom feedlot
As Land Grant University faculty involved in research and extension activities, we appreciate this opportunity to share our thoughts with you, our agency colleagues.