Monday, October 11, 2010
6:00 - 7:30 pm
Pellissippi State Technical Community
10915 Hardin Valley Road, Knoxville
J.L. Goins Administration Building, Cafeteria Annex
Characterization of Karst Systems to Support EIS Decisions
To relieve traffic congestion in south Knoxville, the Tennessee Department of Transportation (TDOT) is evaluating, through an Environmental Impact Statement (EIS) process, various alignment options for extension of a major bypass, the James White Parkway. The project area includes the Toll Subwatershed of the Tennessee River Watershed, which is situated in well-developed karst terrain. Due to regulatory concerns regarding potential bypass development through a karst region and potential impact on the threatened Berry Cave Salamander, in support of the EIS, ARCADIS was retained to characterize area hydrogeologic conditions. The work was conducted to determine whether specific karst features/sinkholes within, and immediately around, the Toll Subwatershed (and near proposed roadway alignments) likely connected directly to Meades Quarry Cave, containing the largest known Berry Cave Salamander population. For this work, a semi-quantitative multi-dye groundwater trace was designed and implemented. This included preparation of a work-plan, which focused on detailed geologic definition, and development of a Conceptual Site Model (CSM), such that a focused injection program could be developed using a limited number of dyes. The trace included injecting fluorescein, eosine, Rhodamine WT, and pyranine into strategic sinkholes following background monitoring. After injection, periodic samples from 14 stream/spring locations were analyzed for the presence of dyes for 7 weeks. Positive traces were identified for each of the four injection sites showing a strong strike-oriented flow component within the karst aquifer, some of which were across previously established watershed boundaries. One trace also identified a direct sinkhole connection to Meades Quarry Cave. These findings were consistent with the original understanding of the hydrogeologic system and were used to refine the CSM. The upfront geologic analysis and CSM development will result in cost savings by knowing early in the process, and with high confidence, that the initial proposed alignments will potentially impact the karst system.
Page updated May 26, 2018