Management and Maintenance of Earthen Manure Structures: Implications and Opportunities for Water Quality Protection

Concern about potential water quality impacts of earthen manure storage structures and lagoons has resulted inincreased technical design oversight, but relatively little attention has been paid to management and maintenancerequirements. A detailed onsite survey was used to obtain information about management and maintenance practices at33 earthen structures containing liquid and slurry manures in Iowa. Fiftyfive percent experienced minor spills duringmanure unloading, 27% showed erosion of compacted clay liners caused by agitation or manure inflow, 24% showed evidenceof animal burrows in berms, 12% experienced plugging or freezing of gravity flow inlet pipes, 6% had tree growth in berms,and 6% had inadequate freeboard at the time of the interview. These factors, singly or in combination, were reported orobserved at 76% of facilities surveyed, while 9% experienced major spills since construction. Nineteen technical andeducational publications were also examined and gaps in coverage of related management and maintenance topics wereidentified. Several technical, educational, and policy opportunities are discussed that may reduce risks to water qualityassociated with the operation of earthen manure structures.