Table 6. Permeability Data (After Haynes and Kahn [8| ) 



Specimen 

 No. 



Simulated 

 Depth 



(ft) 



Time 

 (days) 



Permeability, Q 

 (cu ft) 



D'Arcy's 



Permeability 



Coefficient, K^, 



(ft/sec X 10-12) 



CWL-9A 

 CWL-6 



2,520 

 3,760 



21 

 42 



0.34 

 0.52 



0.16 

 0.10 



NOTE: Spheres started the test having the concrete in a wet condition. The procedure 

 for obtaining wet-concrete walls was to place an uncoated sphere on the bottom 

 of the pressure vessel and allow the seawater to fill the inside of the sphere, and 

 then apply hydrostatic pressure. The pressure was maintained usually for 7 days 

 at 500 psi or until the pressure became constant and showed no decrease, thus 

 indicating that the voids of more significant size were filled with water. 



spheres, so it was evident that Sphere 8 leaked. 

 Experience in fabricating concrete spheres has shown 

 that periodically a specimen leaked at a concrete- 

 epoxy joint. 



SUMMARY 



Of the original eighteen spheres emplaced at 

 depths between 1,840 and 5,075 ft, fifteen spheres 

 have been inspected at least once. Of the spheres that 

 were inspected, the one at greatest depth was at 

 4,185 feet, and was performing well after 431 days. 

 Two spheres have imploded; one sphere imploded 

 during emplacement to the depth of 4,3 30 feet and 

 the other sphere imploded during the time interval of 

 1 to 431 days at a depth of 3,725 feet. 



The quantity of seawater that had permeated 

 through the concrete walls was about 0,8 cu ft for the 

 coated spheres (waterproofed concrete) and 1.6 cu ft 

 for the uncoated spheres (non-waterproofed concrete). 



D'Arcy's permeability coefficient, K^, was on 

 the average 0.02 x lO--^^ ft/sec for the coated spheres 

 and 0.06 X lO"^^ ft/sec for the uncoated spheres 

 between the time interval of to 43 1 days on the 

 seafloor. These K^. values were less than the K^. value 

 of 0.13 X lO'-'^ ft/sec obtained from pressure vessel 

 tests on similar uncoated spheres for time intervals up 

 to 42 days [8]. 



The concrete spheres are to remain in the ocean 

 through 1981 with periodic inspections to determine 

 implosion and permeability data. 



ACKNOWLEDGMENTS 



The author wishes to acknowledge the assistance 

 of Mr. L. F. Kahn during the planning and fabrication 

 stages, of Mr. N. D. Albertsen in emplacing the 

 spheres in the ocean, of Mr. P. C. Zubiate as senior 

 project technician, and of Mr. D. W. Widmayer in 

 fabricating the spheres. 



17 



