Howard Frankland Bridge

Howard Frankland Bridge
Barge Mounted Drilling Services

Madrid Engineering Group, Inc., dba Madrid CPWG was asked to assist Terracon with some of the preliminary SPT drilling for the proposed Howard Frankland Bridge expansion project in Tampa, Florida. The bridge connects Hillsborough and Pinellas Counties and is a primary artery between Tampa and St. Petersburg. This proposed design-build project includes constructing an entirely new 6-lane bridge adjacent to the original bridge and then removal of the old bridge.

Madrid CPWG’s work was focused on the bridge approaches at each end which included a total of 30 standard penetration test (SPT) borings completed to an average depth of 61 feet (72.5 feet max depth) from Madrid CPWG’s jack-up barge over water. These borings were for retaining walls associated with the two bridge approaches (14 on the Hillsborough County side and 16 on the Pinellas County side).

Madrid CPWG Approach

Madrid CPWG had recently acquired a jack-up barge to be able to perform projects like this with our own in-house equipment. We mobilized the barge from the existing causeway and found a local boatyard in which to keep the transport boat during the course of the project. All borings were located by the project surveyor (both horizontal and vertical) to assure accurate locations and elevations were presented on the boring logs; survey checks were completed at set up and after boring was completed. Every sample was photo-logged on-site using a template board with a color chart and dimensions for consistency of sample descriptions on the final logs and to make available for future inspection by others if needed.

Madrid CPWG Benefit

There were concerns with the sea grass in the shallow waters where Madrid CPWG’s work was to be performed and concerns that the barge may impact these grasses during low tides. The pads placed at the end of the three spuds limited potential impacts to the size of a typical door for each spud and our ability to jack the barge out of the water assured this limited impact at each boring location regardless of how long the borings might take to complete.

Because we used all of our own equipment it was very easy for us to adjust to some of the changes including extended borings and, more importantly, preparing for Hurricane Irma. We were able to locate a nearby cove that was protected from winds on three sides with very little fetch length in the fourth direction that would assure more limited wave impact. The length of our spuds allowed us to completely jack the equipment out of the water to get above storm surge and wave heights and the barge was unscathed after the hurricane passed much closer than anticipated to our location. The decision not to demobilize the barge allowed very little change to the budget and schedule in spite of extenuating circumstances brought on by the hurricane.