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Innovative applications of subgrade biogeochemical reactors: Three case studies
Author(s) -
Gamlin Jeff,
Cox Jeremy,
Castor Andrew
Publication year - 2019
Publication title -
remediation journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.762
H-Index - 27
eISSN - 1520-6831
pISSN - 1051-5658
DOI - 10.1002/rem.21586
Subject(s) - groundwater , environmental remediation , environmental science , biogeochemical cycle , environmental engineering , plume , waste management , environmental chemistry , contamination , engineering , chemistry , geotechnical engineering , geography , ecology , meteorology , biology
Subgrade biogeochemical reactors (SBGRs) are an in situ remediation technology shown to be effective in treating contaminant source areas and groundwater hot spots, while being sustainable and economical. This technology has been applied for over a decade to treat chlorinated volatile organic compound source areas where groundwater is shallow (e.g., less than approximately 30 feet below ground surface [ft bgs]). However, this article provides three case studies describing innovative SBGR configurations recently developed and tested that are outside of this norm, which enable use of this technology under more challenging site conditions or for treatment of alternative contaminant classes. The first SBGR case study addresses a site with groundwater deeper than 30 ft bgs and limited space for construction, where an SBGR column configuration reduced the maximum trichloroethene (TCE) groundwater concentration from 9,900 micrograms per liter (μg/L) to <1 μg/L (nondetect) within approximately 15 months. The second SBGR is a recirculating trench configuration that is supporting remediation of a 5.7‐acre TCE plume, which has significant surface footprint constraints due to the presence of endangered species habitat. The third SBGR was constructed with a new amendment mixture and reduced groundwater contaminant concentrations in a petroleum hydrocarbon source area by over 97% within approximately 1 year. Additionally, a summary is provided for new SBGR configurations that are planned for treatment of additional classes of contaminants (e.g., hexavalent chromium, 1,4‐dioxane, dissolved explosives constituents, etc.). A discussion is also provided describing research being conducted to further understand and optimize treatment mechanisms within SBGRs, including a recently developed sampling approach called the aquifer matrix probe.