OWNER:
State of Florida Department of Transportation

GENERAL CONTRACTOR:
Hubbard Construction Company
P.O. Box 547217
Orlando, Florida 32854-7217

DISTRIBUTOR:
Contech Construction Products, Inc.
950 S. Winter Park Drive, Suite 300
Casselberry, Florida 32707

DESIGN ENGINEER:
Synergy Earth Systems, Inc.
26240 Equity Drive
Daphne, AL 36526

In 1999, the General Contractor was awarded a contract to construct a bridge over Lake Bosse in Seminole County, Florida. The location of the bridge was such that its alignment would span a low area that contained peat deposits. The low area was expected to be very difficult to access with pile driving equipment due to the soft, compressible nature of the peat. SES was retained by the Distributor to design a crane access road.

The geotechnical investigation at the site disclosed that the location of the bridge was underlain by as much as 115 feet of organic peat, and that the peat was interbedded with layers of silts, sands and clays. SES utilized multiple layers of uniaxial geogrid reinforcing in the design of the crane access road to provide stability for the embankment under the 100-ton crane with a 25-ton pickup capacity. The stability analyses were performed using an effective stress approach. This approach allowed SES to take maximum advantage of the relatively fast rate at which the peat was expected to consolidate and, therefore, gain strength during construction. The crane access roads were successfully constructed during the fall of 1999. Settlement plates monitored during construction indicated that the crane access road settled by as much as 11 feet, reflecting the compressible nature of the underlying peat.