Caloosahatchee ASR PIlot Project - Treatment Facilities 2003

The conceptual design of the treatment facilities for the Caloosahatchee River ASR Pilot Project
identified a need for certain design parameters and other information to be used in preparing a
final design for the project. A treatment system has been proposed that potentially involves a
two stage filtering process, consisting of a settling pond containing underdrains for collection of
the water to be followed by conventional “Declining Rate Gravity Filters”. However, if the
underdrain system were capable of delivering naturally filtered water in quantities needed, then
the gravity filters would not be necessary. Therefore, in order to evaluate the need for the
gravity filters and to properly design the size of the pond and underdrain system a geotechnical
testing program was undertaken.
Additional data were also necessary to develop a basis for design of the disinfection system,
which currently proposes to utilize ultraviolet (UV) light. The UV process is influenced by color
and turbidity of the water, which affect the transmittance of UV light. For the treatment system
design, it is important to have a quantitative knowledge of the relationship of these parameters,
and how they might be impacted by filtration through a soil/sand underdrain system.
The objectives of the study were as follows:
1. Determine the soil profile and hydraulic properties of the shallow sediments at the site of the
pilot project.
2. Determine if local soils can be economically processed to enhance their
filtration/permeability characteristics so that the local soils could be used in constructing an
under drain system or horizontal well system or both.
3. Evaluate expected flow capacity of a representative group of underdrains or horizontal wells
that were to be constructed of local materials.
4. Determine if, for the purpose of the pilot project, imported sands can be expected to represent
the conditions of the processed local soils that would be developed on site so that the pilot
facilities can be built without constructing a soil processing system and incurring high unit
costs for the relatively small volumes associated with the pilot project.
5. Evaluate the level of treatment that might be expected from the subsurface infiltration and
collection system (e.g. an array of underdrains) and horizontal well systems and estimate
performance by construction and testing a small-scale demonstration system using
representative materials.
6. Test and measure the UV light absorbency characteristics of the local surface water for
evaluation and design criteria to apply UV for disinfection in the pilot ASR treatment system.
7. Evaluate the local soils for contamination from chemicals related to the agricultural
operations that have occurred at the site.
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8. Develop a groundwater flow model to appropriately evaluate the conditions that will affect
the design of the infiltration and underdrain system.