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Bioremediation in Fractured Rock: 2. Mobilization of Chloroethene Compounds from the Rock Matrix
Author(s) -
Shapiro Allen M.,
Tiedeman Claire R.,
Imbrigiotta Thomas E.,
Goode Daniel J.,
Hsieh Paul A.,
Lacombe Pierre J.,
DeFlaun Mary F.,
Drew Scott R.,
Curtis Gary P.
Publication year - 2017
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/gwat.12586
Subject(s) - groundwater , environmental remediation , rock mass classification , aquifer , matrix (chemical analysis) , geology , dissolution , soil science , environmental science , geotechnical engineering , chemistry , contamination , ecology , chromatography , biology
A mass balance is formulated to evaluate the mobilization of chlorinated ethene compounds (CE) from the rock matrix of a fractured mudstone aquifer under pre‐ and postbioremediation conditions. The analysis relies on a sparse number of monitoring locations and is constrained by a detailed description of the groundwater flow regime. Groundwater flow modeling developed under the site characterization identified groundwater fluxes to formulate the CE mass balance in the rock volume exposed to the injected remediation amendments. Differences in the CE fluxes into and out of the rock volume identify the total CE mobilized from diffusion, desorption, and nonaqueous phase liquid dissolution under pre‐ and postinjection conditions. The initial CE mass in the rock matrix prior to remediation is estimated using analyses of CE in rock core. The CE mass mobilized per year under preinjection conditions is small relative to the total CE mass in the rock, indicating that current pump‐and‐treat and natural attenuation conditions are likely to require hundreds of years to achieve groundwater concentrations that meet regulatory guidelines. The postinjection CE mobilization rate increased by approximately an order of magnitude over the 5 years of monitoring after the amendment injection. This rate is likely to decrease and additional remediation applications over several decades would still be needed to reduce CE mass in the rock matrix to levels where groundwater concentrations in fractures achieve regulatory standards.