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Hyperbolic cooling tower No. 2 at St. John’s River
Power Park in Jacksonville, FL, stands 450 ft (137
m) tall and 360 ft (110 m) in diameter. When deterioration
was noticed, a condition evaluation performed found
the lintel beam and columns in poor condition with chloride
testing results exceeding the recommended standard chloride
threshold value. Several factors contributed to the deterioration—the
brackish water being used in the tower and the airflow
from the Atlantic Ocean and the river traveling throughout
the cooling tower were producing high oxygen and chloride levels.
Over the years, several attempts at repair proved ineffective,
so in addition to repairs, a cathodic protection system
consisting of encapsulating zinc mesh anodes within a
stay-in-place fiberglass form filled with cementitious
grout was recommended. The scope work included installing
120 lintel beam jackets and 240 column jackets for
a total of 34,000 square ft (3160 square meters) of jacketing.
Prior to installation, delaminated concrete was removed,
concrete surfaces profiled to a minimum ICRI CSP 3, and the corroded reinforcing
bars cleaned.
Work was scheduled for a 5-week period during an outage;
however, an unforeseen delay occurred to accommodate a
chemical cleaning of the internal tower “fill”
or “packing” media. In response, the contractor,
with plant management approval, decided on a 24/7 schedule.
Adding to scheduling challenges were three other contractors
working on the tower during the same period, making the
daily planning meeting held with the owner and other contractors
invaluable. Coupled with the skill of the crew, putting
in more than 16,000 hours, the contractor addressed these
challenges and met the client’s aggressive schedule.
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Owner
Jacksonville Electric Authority—St. Johns River
Power Plant
Jacksonville, Florida
Project Engineer/
Designer
Existing Structures Engineering
Cape Canaveral, Florida
Repair Contractor
Structural Preservations Systems, Inc.
Deer Park, Texas
Material Supplier
Jarden Zinc Products
Greeneville, Tennessee |
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