BCI Engineers and Scientists

BCI was selected by the Southwest Florida Water Management District (SWFWMD) to evaluate and design low-flow protection devices to help restore perennial flow to the upper Peace River. This part of the river completely dries out, sometime for weeks at a time, from artificial flow losses through karst openings induced by regional groundwater withdrawals. BCI has conducted a thorough historical evaluation of this three-mile stretch of the river, dating back to the late 1850s, to understand all of the impacts to the system fully. Field investigations are nearly complete, involving surveys of the stream and floodplain geomorphology, remote sensing and drilling of karst features, field and lab sediment testing, observation and survey of floodplain hydrology and open channel hydraulics indicators, and observations of vegetation as an impact indicator. In addition to the periodic stream flow cessations, BCI has determined that the system is experiencing multiple fluvial geomorphic and vegetative impacts as it erodes and adjusts to the presence of new karst openings.

The combined stressors have resulted in a 30-acre tree canopy die-off, centered on the most active karst field. Rather than simply creating concrete and steel coffer dams around each sinkhole, BCI is recommending a holistic approach to stabilizing the system to optimize restoration benefits. Our general approach is to emphasize use of natural materials that work consistent with riverine dynamics.

One suite of alternatives for consideration includes the following approach:

• Rebuilding natural levees breached by sinkholes using soil bioengineering treatments
• Stabilizing the eroding floodplain by reforesting it using tree species that have demonstrated they can survive in this zone
• Diverting the stream channel away from existing karst openings where it can be done in a manner that enables the main stream to re-occupy abandoned channel bends sustainably that lack karst features
• Backfilling the sinkholes with gradations of semi-permeable rock, sand and/or geotextiles to reduce infiltration and to cleanse the water that does infiltrate.

Despite the fact that other firms have carefully studied this segment of the river and beyond for a Cumulative Impact Assessment as recently as 2007, BCI was selected to work on this assignment given our reputation as a practical and imaginative design firm with unique expertise in the key disciplines of fluvial geomorphology, geotechnical engineering, karst geology, hydrology and riparian hydraulics, sediment transport, and Florida’s stream and wetland ecology. It is precisely this suite of disciplines that enables us to recommend creative and cost-effective design alternatives to improve riparian corridors throughout the state, especially in challenging environments like this one.