Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer
Renken RA, Cunningham KJ, Zygnerski MR, Wacker MA, Shapiro AM, Harvey RW, Metge DW, Osborn CL, Ryan JN. 2005. Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer. Environmental and Engineering Geoscience. 11(4):319-331
Proposed expansion of extractive lime-rock mines near the Miami–Dade County Northwest well field and Everglades wetland areas has garnered intense scrutiny by government, public, environmental stakeholders, and the media because of concern that mining will increase the risk of pathogen contamination. Rock mines are excavated to the same depth as the well field’s primary producing zone. The underlying karst Biscayne aquifer is a triple-porosity system characterized by (1) a matrix of interparticle porosity and separate vug porosity; (2) touching-vug porosity that forms preferred, stratiform passageways; and, less commonly, (3) conduit porosity formed by thin solution pipes, bedding-plane vugs, and cavernous vugs. Existing ground-water flow and particle tracking models do not provide adequate information regarding the ability of the aquifer to limit the advective movement of pathogens and other contaminants. Chemical transport and colloidal mobility properties have been delineated using conservative and microsphere-surrogate tracers for Cryptosporidium parvum. Forced-gradient tests were executed by introducing conservative tracers into injection wells located 100 m (328 ft) from a municipal-supply well. Apparent mean advective velocity between the wells is one to two orders of magnitude greater than previously measured.
- Type
- Journal Article
- Authors
- Renken, R.; Cunningham, K.; Zygnerski, M.; Wacker, M.; Shapiro, A.; Harvey, R.; Metge, D.; Osborn, C.; Ryan, J.
- Units
- SFCN
- Keywords
- Ground-Water Tracers, particle tracking models, Pathogens, triple-porosity system, Well Field Protection