Dye study tracks historical pathway of VOC-bearing industrial wastewater from failed pond at metals coating facility

Nearly 10 years after initiating a ground water assessment and documenting a stable mass of VOC-bearing ground water in the upper karst aquifer, the Post-Closure Care regulatory process required a dye study to trace ground water movement. The regulatory impetus was the location of a major spring, regionally downgradient from the facility, used as a municipal drinking water supply. drilled strategically in the area of highest concentrations of volatile organic compounds (VOCs) of the stable plume was used as the point of injection of fluorescein. Charcoal packets and water samples were collected from 29 locations (on-site monitoring wells, monitoring wells and production wells at an adjacent facility, surface water sites, and the major spring—a diffuse flow conduit spring with three points of emission). The bedrock fracture system in the vicinity of the facility is not well-developed or well-connected. The distances from the injection point to monitoring/sampling locations ranged from 45.7 m (150 ft) to 4.9 km (3.05 miles). The duration of the test, including pre-injection monitoring, was 118 days. tail of potable water (7182 l or 1900 gal) preceded the injection of the dye solution, and a chaser of about 4158 l (1100 gal) followed the injection of fluorescein. The initial movement of the dye was a combination of the head, created by the injection of drinking water and dye, and the non-pumping conditions at the adjacent facility. Within less than 24 h, the imposed head dissipated and water levels in the injection well returned to pre-injection levels. ad imposed or induced with injection resulted in an almost unique occurrence, which pushed water out to the northwest fractures, in pathways other than normal. The only other time that those northwest pathways were probably used, temporarily completing the connection between the facility and the major spring, was when the pond failed, and a slug of VOC-bearing water was induced into the ground water system.