Rationale for Proposed Project Methodologies
Several sediment retention basins currently exist on Little Campbell Creek. According to the
2005 US Fish and Wildlife Service report, these existing sediment retention basins are
insufficient in removing fine sediments suspended in the water column (USFWS, 2005). As
development continues to increase around Little Campbell Creek, it is likely that these sediment
basins have reached their designed capacity. I am proposing research to first analyze the
functionality of the existing sediment basins, and then research ways to improve the sediment
basins using new technologies available for managing suspended sediment.
Research will be conducted with onsite field measurements, labratory analysis and modeling. In
order to develop a solution it will be necessary to do a thorough assessment of the existing
system. Field measurements and laboratory analysis will be conducted to determine the particle
size distribution upstream, downstream and within sediment basins. These measurements will
help identify the inefficiencies of the existing sediment basins to trap finer particles and lead to a
better understanding of the characteristics of sediment transport in Little Campbell Creek. The
field measurements will be taken in the Fall of 2008, when rain run-off is at its peak intensity.
Laboratory analysis will determine concentrations, sediment size, fall velocities and other
characteristics pertaining to the nature of the sediments. A physical model of a sediment basin
on Little Campbell Creek will be constructed, where the new technologies can be evaluated for
their effectiveness in trapping the sediment analyzed in the laboratory. Applying field data
results to a physical model will provide the means to test different technologies and eventually
design a prototype custom to the characteristics of Little Campbell Creek.
An emerging technology called lamella separation is being applied in many water and
wastewater projects around the world, and has potential to provide a cost efficient solution for
sediment control on Little Campbell Creek. Lamella are packs of artificial, parallel plates which
are inclined and placed in the water body. The general concept of lamella technologies is the
ability to artificially reduce the depth suspended sediments must fall or settle while in the
sediment basin. In order for sediment basins to be effective in trapping sediment, the time it
takes the sediments to fall through the water column must be less than the time the water spends
in the sediment basin (resonant time). In general finer particles have slower fall velocities than
larger particles and require longer resonant times to settle out of the water column. Since
increasing the fall velocity of the sediment is not an option, sediment basins are often improved
by increasing the resonant time. This is typically accomplished by increasing the area of the
sediment basin, thus decreasing the flow rate of the water. This can be an expensive solution and
is often not feasible do limited land availability. Installing a network of lamella plates in existing
sediment basins is an attractive alternative to increasing the size of the sediment basins. Instead
of decreasing the flow rate, lamella plates will decrease the distance the suspended sediments
must fall before making contact with the plates. By decreasing this effective distance, the
settling time for the suspended sediment is reduced without altering the flow rate or the area of
the sediment basin. Lamella are widely used in water and wastewater treatment applications and
have proved to be a cost effective method for dealing with large amounts of suspended material
(KOWALSKI, MIĘSO, 2004). Various materials for lamella plates will be evaluated in the physical
model to determine the most cost efficient solution.