1 Introduction 



Background 



Under the Periodic Inspections work unit, selected past Monitoring of 

 Completed Coastal Project (MCCP) structures, and/or structures with unique 

 design aspects that have probable applications to other projects, are considered 

 for inclusion in a periodic monitoring program. Selected sites are presented 

 as candidates for development of a periodic monitoring plan. Those sites 

 receiving favorable response during MCCP program review are inspected and 

 a monitoring plan is developed and presented for approval. Once the 

 monitoring plan for a site is approved and fiinds are provided, the site is 

 reinspected on a periodic basis (frequency of surveys are set based on a 

 balance of need and funding for each monitoring site) to obtain long-term 

 structural performance data. 



Monitoring Approach 



Primary inspection tools used are relatively low-cost remote sensing 

 techniques with limited ground truthing surveys. A majority of the periodic 

 inspections consist of capturing the above-water conditions of the structures at 

 periodic intervals using high-resolution aerial photography. The degree of 

 data analysis, using photogrammetric methods developed for and successfully 

 applied at the Manasquan jetties. New Jersey, and the Crescent City 

 breakwater, California, vary from site to site. A visual comparison of the 

 periodic aerial photographs is used to gauge the degree of in-depth analysis 

 needed to quantify structural changes (primary armor unit movement). Where 

 local wave data are being gathered by other projects or agencies and 

 acquisition of these data can be made at a relatively low cost, wave data are 

 correlated with structural changes. Where these detailed data do not exist, 

 general observations and/or documentation of major storms occurring in the 

 area are presented along with the monitoring data. Use of ground surveys is 

 limited to the level needed to establish the accuracy of photogrammetric techniques. 



When a structure has been photographed at low tide, an accurate, 

 permanent record of all visible areas is obtained. Through the use of 



Chapter 1 Introduction 



