Underlying Memphis, Tennessee, is a prolific aquifer known as the Memphis Aquifer. This unconsolidated water-bearing formation, deposited by the alternate progression and regression of prehistoric seas, reaches its greatest depth near the Mississippi River and outcrops the surface strata nearly 25 miles east of Memphis, known as the Memphis Aquifer recharge area. During the initial settlement of the Memphis area, drinking water was taken directly out of the local rivers; however, Yellow Fever epidemics in the 1870s and turbidity problems with surface drinking water necessitated the populace finding alternative sources of potable water.

About this same time, R.C. Graves, manager of a local ice company, sunk a well to a depth of 354 feet in the downtown area. To this day more than 180 wells have been drilled into the Memphis Aquifer.

Until the 1980s, preservation of this resource was delegated to those who drilled the wells and used the water. As the area population increased and pollution of groundwater became a real possibility, the state of Tennessee came under mandate from the federal government to establish programs that would guard against pollution of this precious resource.

Tennessee Department of Environment and Conservation

Initial steps to systematically protect community water supplies from contamination began with the United States government's Federal Safe Drinking Water Act of 1986. In response to this federal mandate, promulgated through the Environmental Protection Agency (EPA), the state of Tennessee established the Tennessee Department of Environment and Conservation (TDEC) as the premier water regulatory agency within Tennessee's borders. This was to ensure that all drinking water supplies remain within established federal safe drinking water guidelines.

The federal mandate required the state of Tennessee to develop the Source Water Assessment Program (SWAP) in concert with local water utilities and other health agencies. This program required TDEC to determine source water protection areas, identify and map contaminant source inventory (CSI) points, determine the susceptibility of each public water supply to contamination, and geolocate wells within current well fields in addition to CSI points.

University of Memphis, Ground Water Institute

The academic environment at the University of Memphis provided an ideal atmosphere for the study and preservation of underground and surface water supplies. This led the University of Memphis to establish the Ground Water Institute (GWI) in 1992.

TDEC has since contracted with GWI to provide updates for the SWAP community well field Wellhead Protection Plan. This required updates to spatial locations and attribute information for approximately 500 CSI point features and 180 wellhead locations within Shelby County.

To accomplish this workload, GWI employs undergraduate students in the Department of Civil Engineering to fulfill the mandates of the SWAP program. Working under the direction of Dr. Brian Waldron, research assistant professor, and Stephanie Ivey, research associate, the students are required to physically geolocate each wellhead within the 10 well fields of the Memphis Light, Gas and Water utility plus any wells that are maintained by municipalities within Shelby County, Tennessee. Geolocation of CSI points within the Zone 1 and Zone 2 delineation boundaries around wellheads is also a priority as well as the addition of attribute information for each point feature.

William Greve, GIS specialist, decided on using the IPAQ 3670 handheld computer with the receiver portion of the Trimble TSC1 asset surveyor. Combining this hardware with ArcPad 6 provided the perfect spatial data entry platform.

"The beauty of this setup was that a shapefile of points and their associated attribute information could be collected in the field. No extra data manipulation was necessary back at the office," says Waldron.

Also with the advent of ArcPad 6, students themselves found it simple to create the data input forms. This allowed them to collect the required attribute information, working through the form generation capabilities of ArcPad Studio.

ArcPad 6 also provides GWI users with an unexpected time-saving feature: a spatial reference in unfamiliar locations within the county. The students were able to place the Trimble antenna on the top of the GWI truck and follow their progress on the IPAQ to a wellhead location or CSI point. This replaced leafing through pages of maps trying to find city locations that might be only vaguely familiar to students.

For more information, contact William M. Greve (tel.: 901-678-4315, ext. 3572; e-mail: wgreve@memphis.edu).