Publisher's Synopsis
Internal erosion through and under embankments poses one of the greatest threats to satisfactory performance of these type of water retention structures. This document addresses various processes of internal erosion that can occur in soils and how that erosion can, in some cases, result in failure of a dam or levee. Considerations for identifying and understanding potential failure modes and risks related to internal erosion of embankment and foundation materials are presented to aid practitioners in identifying conditions that adversely affect dam safety. Various monitoring methods that can be used to detect evidence of internal erosion as well as methods for long-term performance monitoring are also presented. Possible emergency response actions for short-term risk reduction and numerous approaches of long-term mitigation of internal erosion risks are included. This document addresses evaluation and monitoring of seepage and internal erosion in an effort to collect and disseminate information and experience that is current and has a technical consensus. It is recognized, though, that the study of internal erosion continues to evolve and that not all phases of the process are completely understood. While research continues into these processes, this document attempts to present the best understanding based on current Federal agency practice. Hence, very recent or new, unproven technologies are not discussed. The authors also acknowledge that there are some minor variations in practice for evaluation and monitoring of seepage and internal erosion among the various Federal agencies. They have tried to focus on what they judged to be the "best practice" and included that judgment in this document. Therefore, this document may be different than some of the various participating agencies' own internal practices. Procedures and guidance for "best practices" concerning the evaluation and monitoring of seepage and internal erosion are provided. Currently available information was reviewed, and when detailed documentation existed, it was cited to avoid duplicating available materials. The authors have strived not to reproduce information that was readily accessible in the public domain and attempted to condense and summarize the vast body of existing information and provide a clear and concise synopsis of this information. This document is intended for use by personnel familiar with embankment dams and levees, such as designers, inspectors, construction oversight personnel, engineering geologists, and dam safety engineers.
