Two cores were taken with an Alpine Vibracore at the LORAN-C 

 sounding locations of both soundings 1 and 2. The stratigraphy devel- 

 oped from the core data is shown in Figure 19 as is the stratigraphy 

 developed from soundings 1 and 2. The stratigraphy from sounding 1 

 compares favorably with the stratigraphy from cores 1 and 2 taken 

 nearby. The same good comparison is found between cores 3 and 4 and 

 nearby sounding 2. This again shows that the XSP provides reliable 

 data. 



San Francisco Bay, California 



The XSP was tested at a site in San Francisco Bay (Figure 13a) on 

 16 June 1982. This testing was to evaluate the XSP in a silty-clayey 

 (usually called a "mud") seafloor and to provide supporting soil data 

 for an anchor holding capacity project. 



Three soundings were conducted with the XSP in the 40- foot mode 

 using an LCU as the support vessel. The LCU-1466 was provided by the 

 481st Transportation Company (Heavy Boat) of the U.S. Army Reserves. 

 The XSP was handled with a crane loaded on the LCU and tied down to the 

 deck. The XSP was laid down on deck with the top end hanging out over 

 the bow (Figure 5). The locations of the soundings are shown in 

 Figure 20. Exact coordinates for sounding locations of soundings 1 

 through 3 are not known because navigation equipment was not available. 



The first sounding reached a subbottom depth of 29 feet, and the 

 second sounding reached 38 feet. The third sounding was terminated at 

 20 feet because the increasing current was causing the ship to drift 

 away from the structure which made it increasingly difficult to retrieve 

 the structure. The data from these soundings showed the soil to be a 

 very soft silty clay to clayey silt. The overburden pressure was sub- 

 tracted* from the cone pressure in the analysis of these data. The data 

 from the second sounding is shown in Figure 21. 



No problems were encountered in using the XSP, except for the 

 ship's inability to maintain station. 



*If it is not subtracted, it changes the soil classification to an 

 incorrect classification. 



27 



