HELICAL TIEBACK SEAWALL REPAIRPROJECT INFORMATION
Your Island Escape: From the minute you cross over the Sanibel Causeway Bridge and through the gates, we’re pretty sure the first thing you’ll think is, “Wow”.
South Seas Island Resort is a beautiful place with a genuine old Florida feel. Where you’ll find everything, you need to live that dreamy island life. Where you’re surrounded by a 330-acre wildlife preserve and dolphins and manatees are also regular guests. Where memories are made in every moment and sunsets are so spectacular, we celebrate it every day. We have activities, so many activities. Fill your days with kayaking, sailing, and boating. Bicycling, golf, and tennis. Epic fishing, world-famous shelling, or strolling along our spectacular two-and-a-half mile stretch of private pristine beach. This is a place where you can fill your days at the most relaxing pace.
Originally a key lime plantation 100 years ago, South Seas Island Resort is now truly a destination. Your destination. Don’t you want to just escape?
PROJECT CHALLENGES
During the process of replacing a failing seawall at the entrance into the main yacht basin, multiple buried utilities were discovered beneath the project site. The utilities consisted of core electrical cables from transformers to adjacent condominiums, 4” water lines and multiple irrigation routes. It was determined the individual engineered designed tie-back system would be in conflict with the concealed utility services. The first response from the engineer was to construct a linear concrete grade beam three foot square by 385 foot long.
The proposed grade beam would constitute a change order and be exceptionally difficult to install due to proximity of the new sea wall and proposed depth of tie-back/deadman structure. Concrete grade beam would be required to be formed in place to prevent collapsing of soils due to tide fluctuations and daily rain events. In addition, the contractor would be forced into dewatering the forms prior to concrete placement.
Our understanding of requirements for this project were based on information provided by Benton and Sons Construction, together with engineered plans provided by Hans Wilson and Associates. Selected assumptions that were formulated are based on our experience within the immediate project vicinity. Often times, the lack of soil borings make it challenging to ascertain the correct helical configuration design and length for a project.
HELICAL INSTALLATIONTHE SOLUTION
The project strategy included the installation of forty-six (46) helical piles to support a proposed new “Trueline Vinyl Seawall”. The helical tie-back anchor piles were designed to achieve allowable capacities of 17.5 kips each. Static load test at every fourth tie-back anchor was approximately secured at 19-20 Kips. A Caterpillar 305 12,000-pound excavator equipped with a specialized hydraulic drive head (Digga 12k Drive) was used to revolve anchors into ground. Helical extensions progressed the tieback anchors to distances on the order of 16 to 44 feet to secure required capacities.
All piles had two helical plates with diameters of 10”/12” inches with central square shaft diameters of 1-1/4-inches square.
As Coastal Foundation Solutions was appointed to conclude the tie-back installation, special precautions were taken for efforts to take place in a marine environment. All elements of the installation components were hot dipped galvanized.
Forty-six (46) CHANCE SS125 (1.25-inch square bar) helical tiebacks with a 10”-12” double-helix lead section was installed in difficult soils and beneath complex utility. Fifty-seven (57) additional seven (7) foot SS125 extensions were utilized to reach required load capability due to sub-surface soil variations.
The helical anchor was connected to a specialized galvanized steel female pivot adapter to which a length of 1” galvanized all thread was attached to a ¾” 6” x 6” square plate. This structural configuration was affixed within the concrete seawall cap. The tiebacks anchors were installed approximately every seven (7) foot with additional anchors at expansion joint locations.
SPECIALIZED EQUIPMENT
Coastal Foundation Solutions utilized a vast array of specialized equipment to complete the project. We maintain a fleet of long reach excavators, floating modular barges, hydraulic/pneumatic drills and significant support equipment. It has always been our protocol to possess the correct equipment to perform the work we contract.
WE WELCOME THE OPPORTUNITY TO EARN YOUR BUSINESS
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