Double-flow behavior observed in well tests of an extremely heterogeneous mine-spoil aquifer

Maher, Thomas P.; Donovan, Joseph J.

doi:10.1016/s0013-7952(97)81915-1

Cited by 7 publications

(5 citation statements)

References 30 publications

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“…It is well known that the hydraulic nature of fluid‐flow systems that develop in coal‐mine spoil is heterogeneous due to the bimodal size distribution of spoil sediments. Double‐porosity characteristics, flow‐through conduit‐like networks, and linear‐flow characteristics have been observed and documented in such flow systems (Maher and Donovan, 1997; Hawkins, 2004). In field trials, the vagaries of different fluid flow‐path networks may cause differences in leaching intensity to be observed between spoil piles.…”

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confidence: 96%

Selenium Adsorption onto Iron Oxide Layers beneath Coal-Mine Overburden Spoil

Donovan

Ziemkiewicz

2013

J. Environ. Qual.

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A field experimental study to determine the feasibility of sequestering dissolved selenium (Se) leached from coal-mine waste rock used an iron (Fe)-oxide amendment obtained from a mine-drainage treatment wetland. Thirty lysimeters (4.9 × 7.3 m), each containing 57.7 t (1.2-1.8 m thickness) of mine-run carbonaceous shale overburden, were installed at the Hobet mine in southeastern West Virginia. The fine-grained Fe-oxide was determined to be primarily metal oxides (91.5% ferric and 4.37% aluminous), with minor (<3%) SO and Ca, perhaps as gypsum. The mineralogy of the Fe was goethite, although residual ferrihydrite may have been present. Various thicknesses of this amendment (0.0064, 0.057, 0.229, and 0.457 m, plus a zero-amendment control) were used, ranging from 0 to 2.2% weight percent of the spoil. The control and each treatment were replicated six times to estimate uncertainty due to compositional and hydrological variation. Infiltration of rainfall created leachate that drained to individual batch-collection tanks that were sampled 46 times at approximately 2-wk intervals from 2010 to 2012. Basal Fe-oxide layers in the three highest amendment categories removed up to 76.1% selenium (in comparison to unamended piles) from leachate by adsorption. Only lysimeters with very thin Fe-oxide layers showed no significant reduction compared with unamended piles. Reproducibility of replicates was within acceptable limits for amended and unamended lysimeters. Results indicate that in situ amendment using Fe-oxide obtained from treatment of mine water can sequester Se by adsorption on surfaces of goethite and possibly also ferrihydrite. This process is demonstrated to substantially reduce dissolved Se in leachate and improve compliance with regulatory discharge limits.

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confidence: 96%

Selenium Adsorption onto Iron Oxide Layers beneath Coal-Mine Overburden Spoil

Donovan

Ziemkiewicz

2013

J. Environ. Qual.

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“…Mean hydraulic properties along such channels or fractures may be significantly higher than the rest of the porous medium. In a more recent paper, Maher and Donovan [20] investigated the relationship between extreme heterogeneity and hydraulic test results in a mine-spoil aquifer created by backfilling the excavations during surface mining. They have observed three different drawdown response types during the tests: conventional, rapid response and ''double'' response.…”

Section: Observed Flow Responses In the Boreholesmentioning

confidence: 99%

“…Slug tests are widely used by hydrologists to evaluate hydraulic conductivities of aquifer horizons. Although they are frequently used to evaluate water conductivities of aquifers, soils and minewaste areas created in surface mining [17][18][19][20], their use in longwall overburden is limited. The use of slug tests in active GGVs to measure the transient changes in hydraulic conductivities as a function of time and face location is currently non-existent in the literature.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic conductivity changes and influencing factors in longwall overburden determined by slug tests in gob gas ventholes

Karacan

Goodman

2009

International Journal of Rock Mechanics and Mining Sciences

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“…The transmissivity of the aquifer is generally high but also highly heterogeneous, with the likelihood of numerous preferred-flow pathways (e.g. Hawkins and Aljoe 1992;Maher and Donovan 1997). The dip magnitude and dip direction of the pit floor is thought to have a substantial influence of ground water flow direction and velocity.…”

Section: Aquifer Characteristicsmentioning

confidence: 99%

Alkaline Injection of Concentrated Sodium Hydroxide Solution into an Acidic Surface Mine Spoil Aquifer

2008

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A series of NaOH solution injection experiments were performed as trials for in situ remediation of an acid-producing surface-mine spoil. Both 20 and 50% (w/w) concentrated NaOH solutions were employed. While the spoil immediately down-gradient of the injection wells was neutralized, only about 23% of the introduced Na was recovered at the spring discharge in 3 years of post-injection monitoring. This rate of transport was far slower than the estimated advection rates in the aquifer, indicating that substantial retardation of both Na and the associated alkalinity occurred. This retardation is ascribed to: precipitation of alkaline-earth carbonate hydroxide minerals, as well as metal hydroxide precipitates, consuming injected alkalinity; and reduction of hydraulic conductivity in the peralkaline (pH [ 13) ''plume'' region due to plugging by reaction products. It is likely that Na and alkalinity will continue to leak from this plume region for many years, but at too slow a rate to neutralize AMD at current concentrations. Future injection efforts of this type may be feasible but should use lower concentrations and should be focused further down-gradient, in closer proximity to the springs, where ground water velocities are higher.

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Double-flow behavior observed in well tests of an extremely heterogeneous mine-spoil aquifer

Cited by 7 publications

References 30 publications

Selenium Adsorption onto Iron Oxide Layers beneath Coal-Mine Overburden Spoil

Selenium Adsorption onto Iron Oxide Layers beneath Coal-Mine Overburden Spoil

Hydraulic conductivity changes and influencing factors in longwall overburden determined by slug tests in gob gas ventholes

Alkaline Injection of Concentrated Sodium Hydroxide Solution into an Acidic Surface Mine Spoil Aquifer

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