Project: Steam Enhanced Extraction (SEE) Remediation of Former Waste Oil Site – Phase 2
Southern New Hampshire
Waste oil mixed with TCE, PCE, cis-1,2-DCE, 1,1,1-TCA, benzene, ethylbenzene, and naphthalene
21,456 cy. Treatment to depths of up to 28 ft bgs in a 56,148 ft2 footprint.
Meet ROD soil clean-up goals for naphthalene, VOCs and CVOCs
Number of Heaters
112 clusters each with 2 injection screens, totaling 224 injection screens.
Important Project Details
Approach: The 224 steam injection well clusters each had two injection intervals. 66.3 million pounds of steam were injected, while more than 17.1 million gallons of water were extracted as steam and condensate.
Challenges: Due to the high volume of low-density NAPL, a slurper system was included in the design in addition to pneumatic high temperature pumps, to remove the top layer of oil from the wells. Despite significant winterization of the steam system, some upgrades had to be performed to the system during operation to address freezing.
Results: A total of 69 confirmatory soil samples were collected. ROD clean-up standards were met for all target chemicals, and post-treatment concentrations of naphthalene and benzene were 3.09 and 0.005 mg/kg respectively, measures with a 95% UCL.
What Makes this Project Unique
The steam enhanced extraction (SEE) design was developed to meet EPA Superfund Record of Decision (ROD) soil leachability clean-up goals for benzene, naphthalene, and selected CVOCs at 95% upper confidence limit (UCL) certainty. While the naphthalene treatment goal was the driver for the design, meeting the low benzene ROD standard of 0.1 mg/kg was also a major focus of the remedy.
Steam was supplied at an injection rate of up to 13,000 lbs/hr, and water from the wellfield was extracted at rates up to 40 gpm. The liquid treatment system included a dedicated NAPL slurping system that enables skimming off any LNAPL from all multi-phase extraction (MPE) wells, along with a metals treatment system and associated sludge management system.