detached breakwater section, consists of 131 stone-filled, sheet-pile dia- 

 phragm cells (Figure 20). According to NCC reports, areas of hard limestone 

 limited pile penetration into the sandy lake floor to approximately 7 ft. 



BREAKWATER 

 STEELSHEETPILE 

 DIAPHRAGM 

 AS ORIGINALLY 

 CONSTRUCTED 



STONE-l^T 



CAP 

 LW.D. 



41'-T 



BEDDING STONE 100-500 m 



.579.6 



ABOUT 100 TONS 

 TOE PROTECTION 

 OVER RIPRAP 

 EACH SIDE 



ELEV. -40 



Figure 20. Diaphragm sheet-pile cell construction typical of 

 section C of the Calumet Harbor breakwater 



40. Images of the harbor side of section A reveal a section of a crib 

 which appeared to have been displaced slightly inward. The lakeward face of 

 section A had numerous irregular reflections occurring up to 10 ft behind the 

 face of the breakwater (Figure 21). It is hypothesized that these reflections 

 occur at gaps in the damaged face of the cribs where the acoustic signal has 

 entered a void and has reflected from the fill material within the cribs 

 similar to the records of the cribs in Cleveland Harbor shown in Figure 13. 



41. Records of the harbor side of section B also show several areas 

 were the wooden cribs have may been damaged. Several fan-shaped deposits of 

 stone and gravel extend up to 50 ft from the base of the breakwater. These 

 may be debris cones of fill that have flowed out from holes in the damaged 

 cribs. This occurrence is corroborated by the Calumet Harbor Reconnaissance 

 Report (NCC 1985), which states that there are voids in some of the cribs in 

 this area based on above water inspections. 



42. The round sheet-pile cells can be clearly seen in the records 

 (Figure 22), and they appear to be in good condition. A breach is evident in 



34 



