Choctawhatchee Bay Bridge

Soil Borings and Laboratory Testing

– Madrid Engineering Group, Inc., dba Madrid CPWG was asked to complete soil borings and laboratory testing for the new 2-mile long bridge across Choctawhatchee Bay in Walton County, Florida.  The work included a total of 104 standard penetration test (SPT) borings, most of which were completed from a barge that was positioned at the proposed bridge pier locations while a surveyor was on board.  The borings were completed to depths of up to 200 feet below the water level.  Some of the borings were also completed at soil mix locations where the existing poor soil along the causeway was to be improved.  The project included soil classification and laboratory testing on a relatively large scale.  Madrid CPWG completed the work in 2013 within the set budget of about $1 million for drilling and laboratory testing services.

Madrid CPWG Approach

Madrid CPWG employed additional temporary personnel to allow using two drill rigs, sometimes working day and night (two shifts) 6 to 7 days a week to maintain the aggressive schedule requested by the client.  Temporary casings were used to stabilize the borehole at most locations because the very soft (weight-of-rod) clayey soil at the bay bottom extended to depths up to 50 feet below the water surface.  In-house laboratory testing was completed 7 days a week in large batches while new samples were arriving daily throughout the project.  Additional water and soil samples were obtained from the site to complete environmental testing (Corrosivity, pH, Sulfides, and Electrical Resistance).

Madrid CPWG Benefit –Madrid CPWG completed the project on budget and in 2 months less time than originally proposed which provided additional time for the design team to work on the design-build project for FDOT District 3.  Because of the good work Madrid CPWG performed during the project, Madrid CPWG was asked to complete verification coring at soil mix locations after our drilling was completed.