Time and cost considerations prohibit a detailed assessment of each of the more than 4,000 public water supplies in Virginia.
The age of groundwater is a valuable parameter that serves to inform many types of groundwater availability studies.
Many environmental tracers — such as chlorofluorocarbons (CFCs), SF6, and tritium — are of atmospheric origin.
However, there are several classes of atmospheric trace gases whose application as groundwater age tracers have not been fully explored.
The detection of chlorofluorocarbons and tritium in ground water provides valuable information that can be used for dating and tracing young ground watertechniques that help water-resources managers develop management strategies for shallow ground-water systems.
Young ground water in shallow ground-water systems Young ground water is typically found at depths from 0 to 100 feet in unconsolidated sediments and at depths up to 1000 feet in fractured-rock systems.CFCs also can be used to trace seepage from rivers into ground-water systems, provide diagnostic tools for detection and early warning of leakage from landfills and septic tanks, and to assess susceptibility of water-supply wells to contamination from near-surface sources.