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Monday, June 09, 2008

Marion County Aquifer Vulnerability Assessment (MCAVA) Completed by Advanced GeoSpatial Inc (AGI)

Intended to enhance protection efforts for one of Marion County’s most precious resources, the Floridan Aquifer System, results of a ground-water modeling project have quickly and effectively been put into use by county staff. The Marion County Aquifer Vulnerability Assessment, or MCAVA, completed by Advanced GeoSpatial Inc. in March of 2007, is being intensively applied by planners, engineers, and environmental regulators working throughout the county in the protection of ground water.

The Floridan Aquifer System is the most important source of water in Marion County; its use is estimated at 80 million gallons of water per day. Numerous fresh water springs including Silver, Rainbow, Silver Glen, Indian Creek, and Juniper arise from the Floridan Aquifer System and much of their springsheds lie within the county.

Marion County Board of County Commissioners recently approved acceptance of the MCAVA project as the county’s official tool in the evaluation of ground-water resource protection, and in doing so replaced the outdated DRASTIC model previously in use.

A major goal of the county’s Transportation Department was to assist in prioritizing potential projects identified through the watershed management program and assist in selecting projects under the Clean Water Grant Program. Higher vulnerability areas are targeted ahead of other similar areas for improvement because protection of ground-water resources is a core component of the department’s mission.

Though managed by the Marion County Clean Water Program of the Transportation Department, the MCAVA project results have been widely used throughout other departments in the county.

All corridor studies recently completed by the Marion County Planning Department include use of the MCAVA model to assess aquifer vulnerability in each study area. These include the Greenway Study Area Recommended Master Plan (November 2007) and the U.S. 41 Study Area Recommended Master Plan (January 2008). Essentially, these reports would require a scientific study for parcels within the study area identified by the MCAVA project as “Most Vulnerable” and “More Vulnerable” to show that there will be no adverse ground-water impacts resulting from proposed developments. These studies are to accompany any application for land use and/or zoning change within these areas.

The MCAVA results were also used in the State Road 40 Existing Conditions Report (February 2008) to identify the most vulnerable areas of the Floridan Aquifer System along this route west of Ocala.

Vulnerable zones indicated in the MCAVA project tend to correspond to areas of good water supply, and as a result, the MCAVA model has also proven useful to the county in its search for suitable sites for new water wells to expand public water supply.

The county is in the process of drafting an ordinance that will affect wastewater guidelines. Though still under development, this ordinance seeks to require advanced treatment of domestic wastewater from new residential developments located in higher vulnerability areas as identified in the MCAVA project.

The county also uses MCAVA results for land use amendment reviews, which require reference to the MCAVA results to discover the vulnerability of a specific site.

Supplementary Datasets

Though the central focus of the MCAVA project is generation of an aquifer vulnerability map of the Floridan Aquifer System, AGI developed several important data layers representing the county’s natural features as necessary components for model input. County staff has found these datasets very useful for determining areas of intense sinkhole and karst activity and where the aquifer is not well protected by overlying sediments.

Because water wells are typically best suited for areas where there is limited sinkhole activity, but thick confining sediments, the MCAVA input layers representing these natural features work well for identifying suitable areas.

The Planning Department is also using the model input data to enable staff to make wise planning decisions regarding the locations of potential sinkholes for development and land use practices.

Along with relying on MCAVA results for prioritizing areas in need of water quality improvement, the county’s watershed management plan process, still under development, is relying on model input for determination of intensely karstified areas and to estimate thickness of aquifer confinement.

The MCAVA study is enabling county staff to make improved planning decisions regarding better protection of springs and springsheds and is helping ensure viable, fresh water is available from the Floridan Aquifer System for continued future use in Marion County. MCAVA allows staff to enhance ground-water protection efforts with a science-based, cross validated approach. Staff are pleased with the ease of use of the MCVA results, its wide-reaching utility in multiple departments and also expressed satisfaction with the cost effectiveness of the MCAVA project.

Press Release - Advanced GeoSpatial Inc