Establishment of wetlands 



The use of detached breakwaters to create and/or stabilize wetlands has 

 been discussed previously in this report. This is a relatively new concept, 

 which has only limited prototype applications thus far. Environmental 

 concerns in wetland areas encompass a wide range of issues relative to the 

 specific site. Proper stabilization techniques must be implemented for marsh 

 grass plantings when wetland development is the objective. Detailed 

 information on environmental issues and wetland development can be found in 

 EM 1110-2-5026; EM 1110-2-1204; Landin, Webb, and Knutson (1989); and 

 Knutson, Allen, and Webb (1990). 



Environmental data and project monitoring 



Each project is site-specific and environmental investigations should be 

 designed to meet the requirements of the project area. Baseline environmental 

 data should be collected for a.significant time period to identify potential 

 impacts that must be considered during project design. The baseline study 

 should identify plant and wildlife species indigenous to the project area, 

 determine the existence and location of endangered species, and identify any 

 other potentially detrimental environmental impacts. A post-construction 

 monitoring program, including water quality monitoring, should be considered 

 to evaluate and document the project's influence on the environment. 

 Additional guidance can be found in EM 1 1 10-2-1204. 



Importance of Beach Fill in Project Design 



Detached breakwaters function by redistributing available sand from the 

 littoral environment; they do not provide or create the sediment necessary to 

 maintain a wide protective beach. Consequently, unless additional sand is 

 brought into the system, accretion which occurs in the breakwater's lee will 

 generally be balanced by erosion in adjacent areas. It is strongly 

 recommended that beach fill be included as an element of all breakwater 

 projects to provide an additional source of sediment for planform development 

 and mitigate downdrift effects. Beach fill is especially important in sediment- 

 starved areas where material may not be available to adequately form a beach 

 planform. In these areas, beach response may be only limited (such as in East 

 Harbor State Park, Ohio; Figure 10) or salients may develop very slowly. 

 Depending on the economics of a specific project, a beach fill combined with 

 a breakwater may be the most cost-effective solution to a shoreline 

 stabilization problem. 



104 



Chapter 5 Other Design Issues 



