2 Monitoring Plan and Data 



14 



Armor Unit Targeting and Ground Surveys 



Monuments for both horizontal and vertical reference were established on 

 land and on the caps of the breakwaters to serve as control points for the land- 

 based survey work as well as the photogrammetric work. Targets were 

 established on the concrete armor units to serve as a control to check the 

 accuracy of the photogrammetric work. Ten, ten, and five concrete armor 

 units dispersed over the sea sides and lee sides of the East and West Kahului 

 breakwaters and the Laupahoehoe breakwater, respectively, were targeted and 

 surveyed. A mixture of sizes and types of armor units were targeted 

 (Table 1). Three targets were placed on each concrete armor unit. Target 

 locations were selected to maximize their visibility in aerial photography and 

 to allow for accurate representation of armor unit movement. Each circular 

 target is separated into four, 90-deg quadrants. Adjacent quadrants were 

 painted highly contrasting colors, and opposing quadrants were painted the 

 same color. This style target provides a precise center point at which 

 measurements can be made by both land surveys and photogrammetric work. 

 To minimize the need for repainting targets, an epoxy-based marine paint is 

 recommended. Each target was labeled with a unique pair of alphanumeric 

 characters. The alpha characters identify the unit and the breakwater on 

 which it resides, and the numeric characters identify the target on the armor 

 unit. For example, armor unit "KEA" indicates a unit on the Kahului East 

 breakwater that is unit A of 10 units A through J targeted on Kahului east, 

 which has three targets labeled KEA-1, KEA-2, and KEA-3 (Figure 9). 

 Figures 10-14 show the locations of all targeted units on the Kahului and 

 Laupahoehoe breakwaters. 



The targets on the concrete armor units had their positions surveyed in 

 September 1991 and October 1992. The first survey work, along with initial 

 targeting, was conducted by POD's surveying branch, while the latter 

 surveying was completed by R.M. Towill Corporation. Results of these 

 surveys are shown in Tables 2-4 and field survey maps are on file at WES. 

 Measured x, y, and z coordinates for each survey are reported along with the 

 relative change that occurred in each coordinate between the two surveys and 

 the vector magnitude of change detected. The horizontal datum is based on 



Chapter 2 Monitoring Plan and Data 



