Hydrogeology and ground-water flow at Levee 31N, Miami-Dade County, Florida, July 2003 to May 2004: As part of the Comprehensive Everglades Restoration Plan

Cunningham, Kevin J.; Wacker, Michael A.; Robinson, Edward; Gefvert, Cynthia J.; Krupa, Steven L.

doi:10.3133/sim2846

Cited by 5 publications

(7 citation statements)

References 8 publications

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“…The term, eogenetic karst, is applied to the land surface and the pore system of young limestone (generally not older than Quaternary age) undergoing shallow, early burial diagenesis [ Vacher and Mylroie , 2002]. Cunningham et al [2004a, 2004b, 2004c, 2006a, 2006b, 2008] described the Biscayne aquifer in a cyclic depositional context to define the effects of relative sea level change and sedimentary processes that produce observed stratigraphic cycles. This work builds on the concept of five Quaternary marine units proposed by Perkins [1977] for the Miami Limestone and Fort Thompson Formation.…”

Section: Biscayne Aquifer and The Miami‐dade Northwest Well Fieldmentioning

confidence: 99%

“…This article summarizes the results of hydraulic, geophysical, and tracer tests conducted in April 2003, which in combination with the improved stratigraphic mapping conducted by Cunningham et al [2004b, 2004c, 2006a, 2006b, 2008] provide a better understanding of the character of the void space, and a hydrogeologic conceptual model of groundwater flow paths and residence times. Companion papers [ Shapiro et al , 2008; Harvey et al , 2008] describe the results of a controlled tracer test conducted in February 2004.…”

Section: Introductionmentioning

confidence: 96%

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Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow

Renken

Cunningham

Shapiro

et al. 2008

Water Resources Research

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[1] The Biscayne aquifer is a highly transmissive karst limestone that serves as the sole source of drinking water to over two million residents in south Florida. The aquifer is characterized by eogenetic karst, where the most transmissive void space can be an interconnected, touching-vug, biogenically influenced porosity of biogenic origin. Public supply wells in the aquifer are in close proximity to lakes established by surface mining. The mining of the limestone has occurred to the same depths as the production wells, which has raised concerns about pathogen and chemical transport from these surface water bodies. Hydraulic and forced gradient tracer tests were conducted to augment geologic and geophysical studies and to develop a hydrogeologic conceptual model of groundwater flow and chemical transport in the Biscayne aquifer. Geologic and geophysical data indicate multiple, areally extensive subhorizontal preferential flow zones of vuggy limestone separated by rock with a matrix pore system. The hydraulic response from an aquifer test suggests that the Biscayne aquifer behaves as a dual-porosity medium; however, the results of the tracer test showed rapid transport similar to other types of karst. The tracer test and concurrent temperature logging revealed that only one of the touching-vug flow zones dominates transport near the production wells. On the basis of the rising limb of the breakthrough curve, the dispersivity is estimated to be less than 3% of the tracer travel distance, which suggests that the fastest flow paths in the formation are likely to yield limited dilution of chemical constituents.

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Section: Biscayne Aquifer and The Miami‐dade Northwest Well Fieldmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow

Renken

Cunningham

Shapiro

et al. 2008

Water Resources Research

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“…Permeable ground-water flow zones within the Biscayne aquifer, however, appear to be semiconfined in an area southwest of the Northwest well field (Cunningham et al, 2004c). In north-central MiamiDade County, the change in hydraulic head in response to hydrologic stress (withdrawals, precipitation, and canal stage) in more deeply buried water-bearing strata usually mirrors those fluctuations that occur at the water table.…”

Section: Hydraulic Test Activitiesmentioning

confidence: 99%

Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer

Renken

Cunningham

Zygnerski

et al. 2005

Environmental and Engineering Geoscience

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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. Touching-vug, stratiform flow zones are efficient pathways for tracer movement at the well field. The effective porosity for a continuum model between the point of injection and tracer recovery ranges from 2 to 4 percent and is an order of magnitude smaller than previously assumed. Existing well-field protection zones were established using porosity estimates based on specific yield. The effective, or kinematic, porosity of a Biscayne aquifer continuum model is lower than the total porosity, because high velocities occur along preferential flow paths that result in faster times of travel than can be represented with the ground-water flow equation. Tracer tests indicate that the relative ease of contaminant movement to municipal supply wells is much greater than previously considered.

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“…Fresh water flowing past the outer wall of the matrix and through the macropores that penetrate the samples greatly magnifies the infiltration into the matrix, even using relatively low ground water velocities. The value of specific discharge simulated in the experiments, 0.00025 m/s, is less than the tracer velocity of approximately 0.0045 m/s observed during a forced gradient tracer test by Renken et al (2005a) within the study area of Cunningham et al (2004a, 2004b, 2006a, 2006b) that used rhodamine WT and D 2 O. While values for both specific discharge and tracer velocity are less than the interstitial velocity, both are apparent velocities that are related to the bulk advection of water.…”

Section: Discussionmentioning

confidence: 55%

“…Notwithstanding the outward resemblance the Biscayne Aquifer holds to other eogenetic karst aquifers, detailed studies of ground water flow within the Biscayne Aquifer (Renken et al 2005a; Cunningham et al 2004a, 2004b, 2006a, 2006b) illustrate dissimilarities, even from relatively young Cenozoic karst aquifers elsewhere in Florida (Florea and Vacher 2006; Florea et al 2007; Martin and Dean 2001). Specifically, in the study area of Cunningham et al (2004a, 2004b, 2006a, 2006b), there is a dominance of ground water flow through the tabular‐shaped stratiform zones of highly interconnected, centimeter‐scale, touching‐vug porosity (Figure 1; Renken et al 2005a; Cunningham et al 2004a, 2004b, 2006a, 2006b). Detailed field investigations indicate that the preponderance of the touching‐vug porosity is related to trace fossils and specifically related to postdepositional burrowing activity of callianassid shrimp (Cunningham and Curran 2007).…”

Section: Introductionmentioning

confidence: 99%

NMR Imaging of Fluid Exchange between Macropores and Matrix in Eogenetic Karst

2009

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Sequential time-step images acquired using nuclear magnetic resonance (NMR) show the displacement of deuterated water (D(2)O) by fresh water within two limestone samples characterized by a porous and permeable limestone matrix of peloids and ooids. These samples were selected because they have a macropore system representative of some parts of the eogenetic karst limestone of the Biscayne Aquifer in southeastern Florida. The macroporosity, created by the trace fossil Ophiomorpha, is principally well connected and of centimeter scale. These macropores occur in broadly continuous stratiform zones that create preferential flow layers within the hydrogeologic units of the Biscayne. This arrangement of porosity is important because in coastal areas, it could produce a preferential pathway for salt water intrusion. Two experiments were conducted in which samples saturated with D(2)O were placed in acrylic chambers filled with fresh water and examined with NMR. Results reveal a substantial flux of fresh water into the matrix porosity with a simultaneous loss of D(2)O. Specifically, we measured rates upward of 0.001 mL/h/g of sample in static conditions, and perhaps as great as 0.07 mL/h/g of sample when fresh water continuously flows past a sample at velocities less than those found within stressed areas of the Biscayne. These experiments illustrate how fresh water and D(2)O, with different chemical properties, migrate within one type of matrix porosity found in the Biscayne. Furthermore, these experiments are a comparative exercise in the displacement of sea water by fresh water in the matrix of a coastal, karst aquifer since D(2)O has a greater density than fresh water.

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Hydrogeology and ground-water flow at Levee 31N, Miami-Dade County, Florida, July 2003 to May 2004: As part of the Comprehensive Everglades Restoration Plan

Cited by 5 publications

References 8 publications

Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow

Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow

Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer

NMR Imaging of Fluid Exchange between Macropores and Matrix in Eogenetic Karst

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