-10 

 UJ -15 

 ^-20 

 1-25 

 !5 -30 

 ^-35 



LU 









SECTION C-C 







■^ — 





---'" / 



^-^^^_ — — 



^^^^ 







100 



200 300 

 DISTANCE IN FEET 



400 500 



1 1986 SURVEY 



1892 SURVEY 1995 SURVFy 1 







Figure 35. Cross sections tiirough Area A, Section C-C for 1 986, 1 992, and 1 995 surveys 



or impacted the structure's stability. An accumulation of sediment has developed 

 north of and adjacent to the detached breakwater with an underwater spit migrating 

 toward the entrance channel. The underwater spit also has shifted in location 

 somewhat, but no navigational difficulties have been experienced to this point. 

 Inside the harbor, an accumulation has occurred due to material moving in between 

 the east end of the detached breakwater and the shoreline. This material, however, 

 is not depositing in the navigation channel or mooring areas. 



Results of the three-dimensional model investigation predicted shoaling patterns 

 precisely at St. Paul Harbor. The fixed-bed model could not be used to quantify the 

 volume of sediment moving in the area, but could qualitatively predict sediment 

 patterns and areas of accumulation. The model indicated sediment would accumu- 

 late north of and adjacent to the detached breakwater and migrate toward the 

 entrance channel. It also indicated sediment would move into the harbor between 

 the detached breakwater and the shoreline, but would not accumulate in the mooring 

 areas. These predictions are shown in Figure 10. Also note that tracer material in 

 the model was swept clean at the head of the breakwater extension, which would 

 indicate possible scour conditions. 



The broken/cracked armor imit survey of the St. Paul Harbor main breakwater 

 during July 1993 revealed a total of 73 broken or cracked armor stones above the 

 waterline. Of the 73 stones, 7 stones were located on the crest, 3 1 on the seaward 

 slope, and 35 on the harbor-side slope. In the vicinity of the northernmost dock at 

 sta 14-f-30 (the seaward end of the additional layer of armor stones on the break- 

 water), some void areas between adjacent capstones were noted. The capstones had 

 migrated away from each other. 



The Jime 1994 survey yielded a total of 13 1 broken or cracked armor stones. Of 

 these 131 imits, 24 were located on the crest, 59 on the seaward slope, and 48 on the 



Chapter 2 Monitoring Program 43 



