Wildlife and safety of earthen structures: a review

A wide range of nuisance wildlife dwells in proximity to and within earthen dams and levee systems. Burrowing animals often dig tunnels and holes inside earth structures for habitat or grub and flatten the external slopes for maneuvering and in search for food or preys. Other animals and cattle have less invasive effects on earthen structures. Most of these detrimental activities result in altering external and internal geometry of earthen structures. Damage caused by wildlife in earthen hydraulic structures is typically associated with internal and external erosion and sometimes boils. Animal burrows have an adverse impact on the hydraulic performance and structural integrity of the earthen dams. In addition to their direct damage, wildlife activities could have serious influence on human life, public health and safety, agriculture, food chain, environmental balance, and ecology. Several federal, state, and local agencies in the United States and other agencies and organizations worldwide have reported information on observed wildlife activities in earth dams and levee systems. This information, however, is generally incomprehensive and often sparsely published in local periodicals and maintenance reports. The consequences of animal presence and their activities on earthen structures are recognized by some involved agencies; however, they appear to be generally given disproportionate attention. As such, the majority of the pertinent literature addresses wildlife damage to earthen structures as a nuisance issue that require more efficient management plans and proper maintenance procedures. This review article summarizes published articles as well as internet cited material on nuisance wildlife behavior in earth dams and levee systems. More emphasis is placed on the animals that pose imminent threats to the performance and functionality of earthen structures. Common characteristics of animal burrows and intrusions in earthen dams are discussed and summarized. Documented damages and reported failures of earth structures initiated by animal activities are compiled. Current wildlife management techniques are discussed. Available estimates of cost of damages and failures due to wildlife intrusions are also highlighted.