Basis of Design Book 2 - City of St. Petersburg

Memorandum
March 1, 2010
Page 5 of 6
Pier Replacement Costs:
Open pier costs were based on reinstalling the pier “in-kind” assuming precast/prestressed concrete
piles, cast-in-place concrete pile caps and beams, and a cast-in-place concrete deck capable of
supporting light traffic.
As previously mentioned, work in the limited access area is complex due to mobility challenges in and
around the ‘inverted pyramid’ building. Costs developed include the installation of new cast-in-place
concrete pile caps, beams and deck and the repair of piles under the ‘inverted pyramid’ building, all in
a confined construction environment. Pile encasement or jacketing is the assumed method of pile
repair for this estimate. The jackets will require an underwater application with divers, boats and
barges to stage the work.
Two different pile jackets were evaluated. The first pile jacket is a standard Florida Department of
Transportation (FDOT) integral pile jacket with corrosion protection. This solution is anticipated to
provide up to a 30-year design life. The following steps are anticipated for this repair:
1. Removal of concrete from the existing piles outside of the reinforcing
2. Attachment of cathodic protection anodes to the existing steel
3. Construction of a new steel reinforcement cage and attachment of anodes
4. Placement of a fiberglass jacket around the pile
5. Encasement of pile and new cage with concrete using the jacket as a form
The second pile jacket repair method uses a similar jacket but does not include a cathodic protection
system. This jacket is anticipated to provide up to a 15-year design life.
Summary of Service Life and Costs:
New marine structures are designed for a minimum 50-year design life, which can be extended with
proper repair and maintenance. The City of St. Petersburg has provided this level of care for the
existing pier and as a result has extended the service life to 90 years.
The existing ‘inverted pyramid’ building and associated foundations are approximately 40 years old.
The existing piles considered for reuse are approximately 90 years old. Reuse of these structures will
require continual maintenance for the rest of their service life. Working in the limited access area will
increase the new construction cost by roughly 3 times and only provide an additional 30 years of
service life in lieu of the minimum 50-year service life of a new structure. Refer to the table for a
summary of the probable construction costs for the pier demolition, building foundation demolition
and pier replacement.