1 10 



Time (days) 



Figure 23. Example of results from a long-term settlement test 

 (in Mugu lagoon sediments). 



In-Situ Sediment Density— Water Content Probe 



A device to measure sediment density and water content is being 

 considered for development by NCEL. It is contemplated to design this 

 device for a 1 0-foot sediment penetration initially. With the capability of 

 rapid in-situ determinations, this tool will be useful in site survey and selec- 

 tion procedures. It is anticipated to use the collected results from this device 

 combined with the other in-situ tests for the design and analysis of small 

 structures and footings (<10 feet square). 



Corers 



Oceanographic corers have been the primary tool for retrieving 

 sediment samples for engineering and geological analysis. Several types of 

 these corers and other samplers with respective manufacturers are listed in 

 Table B-1. Corers commonly used include the Kullenberg, Ewing, and other 

 miscellaneous types such as the Phleger and free-fall corer (Boomerang and 

 Moore Free Fall). With the objective of decreasing sample disturbance by 

 attempting to fulfill criteria for corers suggested by Hvorslev, 20 several 

 corers have been developed including the Hydroplastic by Richards and 



37 



