BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

Pope has developed a shorezone mitigation classification system as summarizedbelow (Table 8-1) 7 .Table 8-1: Types of Mitigation AlternativesProtectionModerationRestorationRetreatAdaptionMITIGATION TYPECOMMON PHRASE“Draw the line”“Slow down the erosion rate”“Fill and maintain the beach”“Do nothing or no project”“Live with it”The protection category is divided into armoring for storm defense (e.g., lakewalls, bulkheads and revetments) and moderation (e.g., groins, breakwaters) forerosion control and backshore stabilization. Beach nourishment or restorationis often called a soft engineering alternative in contrast to the hard engineeringapproaches that were traditionally relied on for achieving shorezoneprotection. Adaptation and retreat represent the “live with it” and “no project”alternatives (abstention) which do not rely on using engineering solutions tomitigate shorezone geomorphic processes and its associated erosion andsedimentation. 8Historically, many coastal and lake shore properties were stabilized andhardened with concrete and steel in order to protect development from waveaction and erosion. Today, there is interest in developing shorelines formultiple purposes so that additional benefits can be retained and accrued. Softengineering approaches have been developed to use geomorphic and ecologicalprinciples and practices to reduce erosion, increase stabilization, and securepublic safety while also enhancing habitat, improving aesthetics, and reducingcosts. 9The traditional types of lake shore armoring such as lake walls, bulkheads andrevetments are still often relied on for protecting backshore cliffs and bluffs.The cost of armoring must be analyzed during the planning phase but the priceis often justified when wave damage consistently threatens substantial humaninvestment. Stabilization for headland bluffs and shoreline terraces generallyrelies on the use of breakwaters, groins, and the preservation of backshorewetlands and Stream Environment Zones (SEZs) to moderate sedimenttransport processes and reduce local erosion rates. These types of structures canbe considered where chronic erosion is a problem due to a diminished littoralsediment supply. 107USACE, 1995, EM 1110-2-1810, Engineer Manual Engineering and Design: Coastal Geology andUSACE, 2008, Coastal Engineering Manual - Parts I-68USACE, 1989, EM 1110-2 -5025, Environmental Engineering for Coastal Shore Protection9USACE, 1984, USACE Waterways Experiment Station, Vicksburg MI, Shore Protection Manual, 4 thed. 2 Vol.10USACE, 2008, Coastal Engineering Manual - Parts I-6TRPA BMP HandbookCHAPTER 8: Shorezone Protective Structures and BMPs2012 Page 8-5