Living Docks: Structural Implications and Determination of Force Coefficients of Oyster Mats on Dock Pilings in the Indian River Lagoon
Abstract
Brevard County, Florida, is facing rapid population growth and increased
pollution entering the Indian River Lagoon (IRL), impairing water quality and
damaging the ecosystem. This is problematic not only for public health and
environmental stability, but also for the economy. The Living Docks initiative was
created to combat environmental degrade in the lagoon and restore natural functions
back to the ecosystem. With increased urbanization along coastal systems, there is
opportunity for new forms of ecological engineering such as Living Docks, which
attaches oyster mats to dock pilings as a means to promote the growth of filter feeding
organisms. It is expected that with the addition of oyster mats and biofouling, the
forces on the dock piling will increase. In order to analyze the structural effect of the
oyster mats as part of Living Docks, a scale model was tested in the Florida Institute
of Technology’s wave tank. The three main objectives of this study were to: (1)
measure forces from a scaled down simulation in a wave tank by use of a strain gauge,
(2) determine drag and inertia coefficients from conditions expected in the IRL, and
(3) compare calculated forces of Living Docks in the IRL to national design standards.
Three phases were tested: a plain piling (phase 1), a piling with a freshly deployed
oyster mat (phase 2), and a piling with an oyster mat that has accumulated four
months of biofouling (phase 3). Results proved there is approximately a 75%
increase in forces by adding an oyster mat to a dock piling, and a 115% increase from
a bare piling to one with significant growth. The force coefficients were determined 𝐶𝑑 = 1.31 and 𝐶𝑚 = 1.01 which can be applied to future designs in any location.
There was no indication of hazardous effects on the host dock piling proving Living
Docks is a safe and reliable restoration effort that can be easily implemented with
any dock.