Hydrocarbon-impacted groundwater and free-phase hydrocarbons (FPH) were seeping into a series of canyons within areas 2, 3 and 5 at a Texas refinery. The company hired Burns & McDonnell to capture the groundwater and FPH. Our solution separated the substances and recycled them to the refinery for treatment and/or processing. The primary contaminant of concern was benzene.
The hydrocarbon-impacted groundwater and FPH was recovered via groundwater collection systems consisting of more than 1,000 feet of French drain and a collection sump in Area 3; over 900 feet of French drain, a bentonite concrete cutoff wall and a collection sump in Area 5; and a 5-foot diameter HDPE culvert underlain by a French drain system, a bentonite-concrete cutoff wall, recovery wells and a collection sump in Area 2. The collection systems were installed within the canyons and collected the hydrocarbon impacted groundwater in downstream sumps while preventing the impacted water from contacting clean surface and stormwater. Construction activities associated with the collection systems were completed under Level C personnel protection due to elevated benzene concentrations in the air.
The hydrocarbon-impacted groundwater and FPH collected in the Area 3 sump are pumped to a treatment unit with an oil/water separator and receiver tanks. The oil/water separator separates the FPH from the water and directs the streams to either an oil or water receiver tank. The captured FPH in the oil receiver tank is pumped to an existing crude unit oil tank and the water in the water receiver tank is pumped to an existing benzene stripper for benzene removal/separation. The benzene stripper bottom water is routed to the refinery’s wastewater treatment center before discharge. Hydrocarbon-impacted groundwater and FPH collected in the Area 5 sump is separated in the sump, and the water and FPH is pumped to either an oil or water receiving tank before being discharged to the refinery’s wastewater treatment or waste oil systems. Hydrocarbon-impacted groundwater collected in the Area 2 sump is discharged directly into the refinery’s wastewater system.