Examination of the data in Appendix C reveals that cross sections of the break- 

 water were similar in both 1994 and 1996. Accretion of stone along the toe of the 

 harbor-side slope of the structure is shown at stas 1 1+00, 12+00, and 13+00. This 

 was an accumulation of small stones which were noted during the 1996 broken 

 armor stone survey. CENPA personnel inspected the breakwater in November 1 996 

 after a large storm and determined the small stones coming out of the structure were 

 chinking stone used during breakwater construction. Approximately a 1 .8-m (6-ft) 

 layer of this small stone was placed directly under the armor layer during 

 construction. 



In summary, the photogrammetric surveys of the St. Paul Harbor breakwater 

 extension were very effective in accurately mapping the above- water portion of the 

 structure and showing changes in el occurring from 1994 to 1996. Results indicated 

 that low areas existed along the length of the breakwater. The higher portion of the 

 breakwater extension seaward of the roadway was at least 0.61 m (2 ft) below its 

 design el over 29 percent of the length of the structure. Only 5 percent of the break- 

 water length was at, or above, its design el. This could contribute to the undesirable 

 overtopping of the breakwater being experienced. As stated earlier, quantifiable 

 overtopping rates were not obtained during the monitoring effort. However, it 

 would have been difficult to correlate them with the two-dimensional model results 

 had they been secured. The elevation of most of the prototype breakwater in this 

 vicinity is below its +1 1 .3-m (+37-ft) design, and the el of the structure tested in, 

 and recommended by, the model was +1 1 .9 m (+39 ft). For the outer portion of the 

 breakwater extension, 9 percent of the structure length is at, or above, its design el 

 of +9. 1 m (+30 ft), with 98 percent within 0.61 m (2 ft) of its design el. The break- 

 water extension may have subsided after initial construction, causing the lower- 

 than-design elevations; however, essentially no change in el occurred between 1994 

 and 1996 based on results of the photogrammetric analysis. 



56 



Chapter 2 Monitoring Program 



