Vertical-Flow Rates Through Miocene Sediments in South- Central Georgia

A cluster of six monitoring wells installed on Georgia Southern University campus were used to investigate the vertical-flow rate through upper Miocene sediments in south-central Georgia. The field site consists of three well nests, with a deep and shallow well at each nest. Wells range in depth from 16 to 87 feet and are instrumented with dedicated data loggers. Geophysical and stratigraphic logs show that the site consists of complexly interbedded sand and clay facies with individual units grading out laterally between well nests, a distance of less than 400 feet. Temperature and hydraulic head were recorded over a 14 month period and compared to atmospheric data recorded at the campus weather station. From atmospheric pressure data, the barometric efficiency was calculated for the deep wells and found to range from 20 to 35%, indicating that the system is poorly confined. Based on the depth of the deep wells and their fairly rapid response to precipitation, approximately 40 days, a vertical-flow rate of 1.5 feet/day was calculated. Assuming an overall porosity of 25%, the vertical-hydraulic conductivity of the system as a whole was estimated to be 0.6 feet/day.