Groundwater at a former gasoline service station was impacted by leaking underground storage tanks and associated piping. Although contaminant trends and geochemistry suggested that MNA could be an appropriate site management strategy, the need for more rapid site closure led to a decision to enhance biodegradation of BTEX and MTBE aerobically with injection of an…
A site impacted by chlorobenzene was managed by MNA. Site managers asked: “Can we confirm that observed decreases in chlorobenzene concentrations are resulting from biodegradation as opposed to dilution?” and “Would injection of an oxygen release compound result in enhanced rates of aerobic biodegradation of chlorobenzene under site conditions?” The answers to both questions were yes. …
Site stakeholders needed conclusive evidence that biodegradation of benzene and naphthalene was occurring under existing site conditions to accept MNA instead of a more aggressive strategy. Stable isotope probing (SIP) studies using Bio-Traps® amended with 13C benzene or 13C naphthalene conclusively demonstrated in situ biodegradation occurred under existing site conditions. MNA was accepted as the remediation strategy.
Site managers were considering monitored natural attenuation (MNA), biostimulation, and bioaugmentation as remediation strategies at a site impacted by a complex mixture of chlorinated hydrocarbons including PCE, TCE, 1,1,2-TCA, 1,2-DCA, cis-DCE, and VC along with high concentrations of sulfate. Site managers had several questions including: Is complete reductive dechlorination of all chlorinated solvents possible? Is…
At a petroleum pipeline release in a remote area Bio-Traps® and CENSUS® qPCR for BTEX catabolic functional genes proved stimulation of BTEX biodegradation in impacted groundwater and provided an additional line of evidence to support acceptance of an MNA management strategy at the site. Site managers asked: “Can molecular biological tools provide even more evidence…
An In Situ Microcosm study was conducted to evaluate MNA vs. enhanced anaerobic bioremediation via sulfate reduction at a petroleum impacted site. Site managers asked: “Will the injection of sulfate stimulate anaerobic BTEX biodegradation at this site?” The answer was yes. The ISM study showed conclusively that injection of sulfate at the site would increase the growth of…
A pilot study was conducted at a site where electron donor was injected into groundwater impacted by a mixture of chlorinated solvents. Site managers asked two questions: “Did the electron donor injection stimulate reductive dechlorination?” and “Did injection of the electron donor also increase the potential for abiotic dechlorination through the generation of biogenic FeS?”…
A homeowner dependent on a domestic water well suddenly saw an accumulation of a black precipitant clogging the pre-filter of their water treatment system. Two years previous to this observation there was a release of gas condensate hydrocarbons and saltwater upgradient of their property. The homeowner and their attorneys asked “Is this black precipitant evidence…
Mass reduction by DPE and SVE at a hydrocarbon- and MTBE-impacted site had become uneconomical. Site managers asked: “Can we transition to MNA?” The answer, for the most part, was yes. Post SVE, hydrocarbon and MTBE concentrations showed decreasing trends in most monitoring wells. Additional strong lines of evidence for in situ biodegradation of benzene and MTBE under…
This brochure provides guidance on how to choose the right sequencing approach for a project. The differences and benefits between next generation sequencing (NGS) and whole genome sequencing (WGS) are discussed.