CAFO Liner Requirements

1. Liner Requirement. The permittee shall include in the plan, site specific documentation that no significant hydrologic connection exists between the contained wastewater and surface waters of the United States. Where the permittee cannot document that no significant hydrologic connection through ground water exists, the ponds, lagoons and basins of the retention facilities must have a liner which will prevent the potential contamination of surface waters.

(a) Documentation of No Liner Requirement. The permittee can document lack of hydrologic connection by either: (1) Documenting that there will be no significant leakage from the retention structure; or (2) documenting that any leakage from the retention structure would not migrate to surface waters. This documentation should be certified by a Professional Engineer or qualified groundwater scientist and must include information on the hydraulic conductivity and thickness of the natural materials underlying and forming the walls of the containment structure up to the wetted perimeter.

For documentation of no significant leakage, in-situ materials must, at a minimum, meet the minimum criteria for hydraulic conductivity and thickness described below. Documentation that leakage will not migrate to a surface water must include maps showing ground water flow paths, or that the leakage enters a confined environment. A written determination by an SCS engineer, a Professional Engineer, or qualified groundwater scientist that a liner is not needed to prevent leakage of significant amounts of pollutants into surface waters via perched or ground waters will be considered documentation that no significant hydrologic connection exists.

(b) Liner Construction. Site-specific conditions should be considered in the design and construction of liners. Soil Conservation Service liner requirements or liners constructed and maintained in accordance with Soil Conservation Service design specifications in Technical Note 716 (or its current equivalent) shall be considered to prevent hydrologic connection which could result in the contamination of surface waters. Liners for retention structures should be constructed in accordance with good engineering practices. Where no site-specific assessment has been done by a Soil Conservation Service, Professional Engineer, or qualified groundwater scientist the liner shall be constructed to have hydraulic conductivities no greater than 1*10^-7 cm/sec, with a thickness of 1.5 feet or greater or its equivalency in other materials.

(c) Liner Maintenance. Where a liner is installed to prevent hydrologic connection the permittee must maintain the liner to inhibit infiltration of wastewaters. Liners shall be protected from animals by fences or other protective devices. No trees shall be allowed to grow within the potential distance of the root zone. Any mechanical or structural damage to the liner will be evaluated by a Soil Conservation Service engineer, Professional Engineer, or qualified groundwater scientist within 30 days of the damage. Documentation of liner maintenance shall be kept with the Pollution Prevention Plan. The permittee shall have a Soil Conservation Service engineer, Professional Engineer, or qualified groundwater scientist review the documentation and do a site evaluation every five years. If notified by the State or the Director that the potential exists for the contamination of surface waters or drinking water, the permittee shall install a leak detection system or monitoring wells in accordance with that notice. Documentation of compliance with the notification must be kept with the Pollution Prevention Plan, as well as all sampling data. Data from the monitoring wells must be kept on site for three years with the pollution prevention plan. The first year's sampling shall be considered the baseline data and must be retained on site for the life of the facility.