Pneumatic Fracturing and Sodium Lactate Injection Leads to Successful Treatment of Perchlorate and RDX
A recent ARS project was performed using sodium
lactate to treat ground-water impacted with
perchlorate and RDX at the former Naval Surface
Warfare Center (NSWC) in Silver Springs, Maryland.
To address the low permeability and heterogeneous (saprolite)
geology at the site, ARS was contracted to provide Pneumatic
fracturing (PF) and liquid atomized injection (LAI) services to
distribute sodium lactate within the target treatment zone.
Approximately 1,000 gallons of a 60% sodium lactate solution
were injected into five boreholes, spaced approximately 50 ft
apart within the 10,000 square foot treatment area. Seven monitoring
wells, located 10 to 175 feet (ft) from the injection points, were
used to monitor the distribution and persistence of the lactate and
the effectiveness of the treatment.
During the injection operations, pressure influence was observed in
monitoring wells at distances exceeding 70 ft. Post-injection groundwater
sampling results show effective distribution of the sodium lactate and
significant degradation of perchlorate, RDX and other energetic compounds.
Lactate concentrations as high as 8,400 mg/L were observed in monitoring
wells within the treatment zone three weeks after the injection.
Perchlorate concentrations in the four wells located within the treatment
area were reduced to less than 1 mg/L. Additionally, perchlorate
concentrations were reduced from 160 to 95 mg/L within 6 months at a
distance of 175 ft from the injection points. RDX concentrations were
reduced from 190 mg/L to less than 0.52 mg/L.
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