Lagoons/waste structures that are no longer in use shall be either managed to prevent discharge to surface and groundwaters, or decommissioned through a closure plan. If a discharge does occur from an abandoned animal waste management structure, the farm owner is subject to enforcement action by DWQ. In addition, if a water quality or groundwater problem is identified, DWQ will require proper closure of the structure in addition to enforcement action and possible civil penalty.

For abandoned lagoons and waste structures, proper closure at the earliest possible date is strongly encouraged. An unclosed lagoon is a potential safety and environmental danger as well as a liability to the farmer. The closure plan outlining the closure process shall follow NRCS Technical Standard 709. Proper closure includes verification by a technical specialist that the work was done according to standards and specifications, and the completed Animal Waste Storage Pond and Lagoon Closure Report Form (Appendix 3.1) is submitted to DWQ within 15 days following completion of the closure. The regional DWQ staff must be notified at least 24 hours prior to the start of closure. Once the closure is completed and acknowledged by DWQ, the structure is no longer considered part of the waste management system, is deleted off of the state database, and may be used for other purposes such as for irrigation or as a fishpond.

Either a closure plan or the management of an unused lagoon or waste structure must be included in the CAWMP for facilities operating above threshold as specified in 2H .0217.

Inactive lagoons or waste structures for deactivated facilities (operations with no animals or operating below threshold) shall be properly managed to prevent discharge to surface and groundwaters; however, the waste does not have to be land applied by a certified animal waste applicator.

3.2 Renovation of Existing Animal Waste Management Systems With No Expansion

If a facility is not being expanded but modifications to an existing lagoon are needed to increase its storage or treatment volume, modifications can not be made without meeting current standards or without updating the existing CAWMP. Only minor repairs can be made to the structure. Examples would be work to repair minor erosion or the addition of more soil to the dike to provide greater stability provided the top of the dike is not raised above the design elevation.

If a new lagoon or waste storage structure is added to an existing treatment system (no increase in SSLW since February 1, 1993) to provide additional treatment or storage and is tied into an existing structure (including connection by pipe or lift station), the existing structure does not need to meet current design standards. While it is encouraged that all-existing structures be upgraded to meet current standards any time there is construction on a site, it is not automatically required. The technical specialist shall make a determination on the need for structural upgrades during the evaluation of the overall system. If a determination is made by the technical specialist that the existing structure is not endangered by the connection to the new structure(s) and that it is structurally sound, no upgrades to meet current standards are required. In determining the stability of the structure, the technical specialist should evaluate and document signs of previous discharges, pumping frequency (infrequent pumping suggest leaking), slope stability, and seepage or wet areas along the backside of the dikes.

3.3 Lagoons in Wetlands or flood plains

Lagoons shall not be constructed in wetlands or a 100-year flood plain.

3.4 Design Standards

For a lagoon or waste storage structure constructed after February 1, 1993, the design requirements are contained in the NCAC 2H. 0217 rules, state Statutes, and NRCS and SWCC technical standards, in effect on the date of the design completion as documented through NRCS design approval, a professional engineer (PE) seal, or a CAWMP certification form. (Appendix 2.5A.) Only a PE or NRCS employee with job approval authority may certify waste structures constructed after February 1, 1993. New construction and/or modification requires certification. Certified designs for lagoons and waste storage structures in which construction has not commenced within one year of a design standard change shall be constructed according to the current design standards regardless of the original design date and require recertification.

The SWCC has rescinded its animal waste management standards adopted May 2, 1996 effective January 1, 2001. Certifications made after January 1, 2001 of farms existing prior to May 2, 1996 must meet current NRCS standards.

3.5 NRCS Policy on Modifications

If NRCS provided technical assistance on the original waste structure, technical assistance can be provided by NRCS. If NRCS did not provide technical assistance on the original structure, then assistance generally will not be provided with the modification because of the time required to adequately assess the design and construction of the original structure.

3.6 Overflow Pipes Used for Emergency Spillways

Overflow pipe(s) in lagoons are acceptable as a lagoon emergency spillway, provided they are properly designed for adequate capacity for the design storm and have a stable inlet and outlet.

3.7 Liquid Levels for Staged Lagoons

In a staged lagoon system where the primary lagoon is gravity fed through a transfer pipe into a secondary structure, the top of the transfer pipe shall be set just below the primary lagoon's structural freeboard elevation if the primary lagoon's 25-year, 24-hour storm requirement is calculated into the second structure's temporary storage. Pipe size shall be designed to carry the 25-year storm event without encroaching on the structural freeboard.

3.8 Pumping Markers for Staged Lagoons

Pumping markers are only required in those structures that do not gravity feed through a free flowing (no valve) transfer pipe into a subsequent structure, and in those structures which serve as the primary source for land application. For example, if waste empties from the house into a solids trap, is pumped to lagoon 2, gravity fed to lagoon 3, and then pumped to a solid set system for land application, both the solids trap and lagoon 3 are required to have markers.

3.9 Requirements for Elevation Pumping Markers

NRCS standards require start and stop pumping markers. Since producers are required to record freeboard and available storage capacity under an animal waste general permit, it is highly recommended that they install elevation markers that will clearly identify minimum and maximum liquid levels as well as a gauge that enables accurate determination of the distance between the lowest point on the embankment and the liquid level.

Waste storage structures are designed to be emptied completely and would not require a minimum elevation marker. Anaerobic lagoons are designed with a permanent treatment volume, and would require a minimum elevation marker so the permanent treatment volume is maintained.

3.10 Freeboard for Solids Traps

Older swine operations had lagoons that were dug pits (no dike walls) and were later converted into solids traps with waste pumped to a newer structure(s) to satisfy retrofit requirements of the waste handling system. These structures are allowed to operate with less than the one foot structural freeboard and 25-year, 24-hour storm event storage requirement if:

1. a back-up pump with power source is available in the event of equipment failure to lift waste to a secondary structure,
2. a honey wagon/tanker is available with the capacity to empty the structure, or
3. a secondary containment structure is available to store the waste.

For exemption from the one-foot structural freeboard requirement, consideration must be also given to the location of the seasonal high water table, proximity of the solids trap to drainage ways, flushing volumes and frequencies, and other case-by-case circumstances which may affect the system management. Under no circumstances will a solids trap be allowed to operate with a structural freeboard equal to or less than a 25-year, 24-hour storm event. Solids traps are also required to have a minimal dike wall or comparable best management practice (BMP) in place to prevent outside surface water from entering the structure.

3.11 Trees on Embankments

Trees, shrubs, and other woody vegetation shall not be allowed to grow on the lagoon/waste storage pond embankments. All trees shall be removed in accordance with good engineering practices. Lagoon/waste storage pond areas shall be accessible, and vegetation shall be kept mowed. Removal of trees does not constitute a retrofit requiring a complete structural upgrade to current standards.

3.12 Proper Use of Lagoon (359) Standard

Current NRCS standards allow for design treatment volumes (i.e. Table 2. Livestock Anaerobic Lagoon Criteria) that are lower than in previous standards for farrow/wean, farrow/feeder, and boar/stud operations. However if this is done, the current standards for sludge storage, excess water, etc. shall also be used to properly utilize the standard. Attempting to use these new volumes on existing operations that have been designed and approved under an earlier standard in order to increase the number of animals will be considered an expansion and all current criteria for expansion shall be met.