All About NDEE: Clay Lined Lagoons
From personal onsite wastewater lagoons to municipal wastewater treatment facilities and animal feeding operations, thousands of homes and businesses across the state of Nebraska rely on clay lined lagoons and holding ponds as a trusted technology to control wastewater.
Clay lined lagoons and holding ponds are engineered systems that are designed and constructed uniquely based on their location and intended use. To protect groundwater, the Nebraska Department of Environment and Energy (NDEE) evaluates site criteria and regulates engineering and design specifications used in these systems through Title 123 – Rules and Regulations For The Design, Operation And Maintenance Of Wastewater Works; Title 124 – Onsite Wastewater Treatment Systems; and Title 130 – Livestock Waste Control Regulations.
Before construction can begin on any proposed municipal wastewater treatment facility or animal feeding operation lagoon or holding pond, NDEE groundwater geologists conduct a review of site evaluation documents to determine potential impacts to groundwater.
For all permitted animal feeding operation lagoons, municipal wastewater treatment facility lagoons, and personal onsite lagoons that have a flow rate in excess of 1,000 gallons per day, NDEE engineers review the engineering specifications and the results of a seepage test before these systems can become operational.
Engineering considerations for a lagoon or holding pond can include capacity requirements; surface area that is sufficient to expedite evaporation; interior and exterior slope requirements that mitigate erosion; minimum dike width; minimum freeboard height (distance between the normal maximum operating water surface of the pond and the top of the dike); and, among other considerations, a minimum operating depth to prevent drying and degradation of the liner.
The liner itself also undergoes an engineering process to determine a thickness and compaction rate that prevents seepage of more than one-eighth inch per day, which is the regulatory limit established by the above Titles. If soil borings and tests at a proposed lagoon site are not conducive to sufficient compaction to meet this seepage requirement, the facility will be required to source soil that satisfies that criteria or install a synthetic liner.
After wastewater lagoons or holding ponds become operational at municipal wastewater treatment facilities or animal feeding operations, NDEE performs routine inspections to ensure compliance with regulatory standards.