HDD for Gulfstream Natural Gas—Phase IV

GeoEngineers provided expert geotechnical engineering and horizontal directional drilling (HDD) design and construction consulting services for five HDD installations along the Bartow Lateral pipeline in the waters of Tampa Bay. The HDD installations were part of 17.74 miles of new 20-inch-diameter pipeline connecting the Bartow Power Plant to an existing 36-inch-diameter Gulfstream pipeline.

The pipeline crosses five shipping channels, along with one environmentally sensitive area near shore. To allow for maritime activity, the regulated shipping channels needed to remain undisturbed during construction, and the shoreline could not be spoiled with conventional pipeline construction methods.

Conditions such as adverse weather, rough seas and working on barges made the HDD crossings challenging. The project required divers and underwater equipment as well as innovative methods for tracking HDD progress as the initial hole progressed beneath the ocean floor.

Approach

• Reviewed regulatory requirements, geologic conditions and construction methods for installing the pipeline under the ocean floor
• Analyzed where underground drilling would start and end on either side of shipping channels, as well as where one HDD crossing would end on land at the Bartow Power Plant
• Designed the HDD installations to accommodate future channel expansion and avoid the need for pipeline relocations
• Contained used drilling fluid in a series of designed excavations in the ocean floor, thereby reducing the risk of ocean contamination (YETI)
• Addressed complications of performing drilling operations from one barge to another
• Provided full-time construction observation services at each HDD crossing, including daily reporting of the HDD construction contractor’s actions

Results

GeoEngineers helped complete four crossings offshore in water depths from nine to 34 feet, with crossing lengths of 2,590, 2,050, 2,200 and 1,986 feet. The fifth, 5,062 foot crossing started in Tampa Bay and ended onshore at the Bartow Power Plant.

• The project staff was onsite for the duration of the project and communicated concerns directly to Gulfstream, helping reduce construction delays and resulting in no extra claims for payment from the contractor.
• GeoEngineers’ onsite observations and detailed daily reporting enabled Gulfstream to discover discrepancies in the HDD construction contractor’s as-built records of where the finished pipeline lay underground, saving the company from potential maintenance and repair costs and liability associated with a misrepresented pipeline location.
• GeoEngineers completed its work on time and on budget.