Subsurface investigations at the site revealed layers of loose and compact sand over a deep clay marl. These conditions favor the use of steel friction piles. Past experience has shown that steel friction piles are effective for carrying heavy loads with this type of soil.

Cooper River itself affords good access to the bridge site, with water depth of 40 feet. Quoting directly from HNTB's 1983 Conceptual Design Report (Ref. 4) :

Much of the remainder of this project is across marshes and wetlands associated with these waterways. Barges would be used to transport equipment and materials wherever possible. [See Figure 2.5 .] These would be supplemented by construction access roads on high ground. Temporary timber mat roads may be required in areas otherwise inaccessible. Railroad access is available along the west approach viaduct to the Cooper River Bridge.

fig 2.5

Map 2

Construction access will be particularly difficult for that part of the project across the dredge spoil area. Extending from the Cooper River to Clouter Creek [See Map 2] , the area is used by the U. S. Navy and the Corps of Engineers for disposal of material dredged from the river channels to maintain the waterways. Most of the area is comprised of soft material extending as deep as 25 feet. The consistency of the material is such that the use of construction mats for heavy equipment is not feasible. One possibility for providing access to this area is to dredge a work canal across the disposal area along the bridge alignment. The contractor may have to compensate for the dredged material he deposits elsewhere in the spoil area by raising the height of adjacent dike walls. Required breaks in the existing dike walls would have to be repaired after completion of construction.

No figures for this section.