Dense Nonaqueous Phase Liquids (DNAPLs)
- Policy and Guidance
- Chemistry and Behavior
- Environmental Occurrence
- Detection and Site Characterization
- Treatment Technologies
- Conferences and Seminars
- Additional Resources
In Situ Oxidation
Coal Tar Contamination Remediation
Pollution Engineering 44(5):26-30(2012) [a Pollution Engineering white paper]
At a New York City brownfield, site of a former roofing products manufacturer, a surfactant-enhanced ISCO (S-ISCO) system was implemented to remediate coal tar present as residual NAPL held within the pore spaces of the predominately sandy and silty soil, which included lenses of silt and silty clay. A patented, plant-based surfactant/co-solvent mixture and alkaline-activated sodium persulfate were delivered into the subsurface using a pressure-pulsing injection enhancement technology. Between October 2010 and March 2011, the supplier conducted five months of S-ISCO injections that destroyed >90% of coal tar-related contaminants—PAHs, naphthalene, and BTEX—in the targeted interval.
In Situ Ozonation to Remediate Recalcitrant Organic Contamination
J. Dablow, M. Seaman, and B. Marvin.
International Containment & Remediation Technology Conference & Exhibition, 10-13 June 2001, Orlando, Florida.
Briefly discusses the successful, full-scale application of in situ ozonation at two former MGP sites in Dubuque, IA, and Long Beach, CA.
Record of Decision: Central Hudson Newburgh Site, Newburgh, Orange County, New York, Site Number 3-36-042
New York Department of Environmental Conservation, 120 pp, 2005
For area B between the MGP site and the Hudson River, the following remedy has been selected: installation of tar collection wells and removal of MGP tar from the River Street area followed by ISCO and installation of a containment wall with tar collection on the bank of the Hudson River. NYSDEC believes that the addition of in situ oxidation will likely reach at least some of the mobile tar that could escape detection and capture by collection wells. As with any in situ technique, the most significant limitation is physical—getting the oxidants into close contact with the contaminants is essential. Due to this limitation, ISCO is considered a "polishing step" in this case to address dissolved-phase contamination and widely dispersed drops and stringers of NAPL. NYSDEC does not expect it to be highly effective against discrete pools of NAPL, because the oxidants are delivered in aqueous solution and cannot mix well with discrete bodies of NAPL. No large pools of tar have been identified in this area, despite a very large number of borings drilled, but some could exist. Consequently, the remedy calls for removal of all freely drainable tar prior to injection of oxidants. Because the remedy will leave contamination above unrestricted levels, institutional and engineering controls will be developed in cooperation with the property owners.
Revised Work Plan and Trial Management Plan: Surfactant Enhanced In Situ Chemical Oxidation (S-ISCO®) & Surfactant Enhanced Product Recovery (SEPR™), Block 5 and Hickson Road, Barangaroo, Pilot Trial
New South Wales Office of Environment and Heritage, Australia. 355 pp, 2011
From 1840 to 1921, sections of the Barangaroo site were used to manufacture gas. Portions of the contaminated former gas works infrastructure remain in place beneath the current slab surface and adjacent roadway. This work plan describes the contaminated areas, explains in detail the workings of the innovative SEPR™ and S-ISCO® technologies, provides design information for the pilot test and the injection and SVE systems, and discusses performance measures and the monitoring, health and safety, and waste management plans. S-ISCO® is designed to solubilize contaminants rather than mobilize them. The co-eluted surfactant/co-solvent and oxidant fronts move through the subsurface together and solubilization and oxidation occur simultaneously, such that the contaminants (i.e., TPH, BTEX, PAHs, coal tar) are destroyed in place. The system incorporates water, activator (Fe-TAML and/or sodium hydroxide), VeruSOL® surfactant, and oxidant (hydrogen peroxide and/or sodium persulfate).
Superfund Fact Sheet: Calhoun Park Area Site, Charleston, South Carolina
U.S. EPA Region 4, 2005
Contact: Kenneth A. Lucas, RPM, 404-562-8953, email@example.com
Although recovery efforts are ongoing, coal tar from former MGP operations exists at this site in its original liquid form as DNAPL and is present within the subsurface soils at depths to 50 ft bgs in certain former process areas, which are inaccessible due to the presence of high-voltage electrical equipment. The approach calls for phased ISCO by injection of Fenton's reagents in the upper and middle intermediate sand units off site, and injection of PermeOx Plus® in additional off-site sectors to enhance the natural biodegradation of dissolved-phase constituents. The first phase of the ISCO work began July 25, 2005, and was completed on September 3, 2005. EPA and the South Carolina Department of Health and Environmental Control are currently evaluating the impact of the first-phase work on the contaminant mass and the need for any additional work.
Innovative Green Treatment of Former Manufactured Gas Plant Dense Non Aqueous Phase Liquids using Surfactant-Enhanced In-Situ Chemical Oxidation (S-ISCO™)
G.E. Hoag and J.B. Collins.
International Gas Union Research Conference, 2008, Paris. 18 pp, 2008
Surfactants and cosolvent/surfactant mixtures can increase the apparent solubility of VOCs and SVOCs in MGP soils for subsequent oxidation using activated persulfate. This process does not require separate mobile-phase NAPL recovery as the purpose of the surfactant/cosolvent is to increase the apparent solubility of the NAPL in the aqueous phase and not to mobilize the NAPL phase. This presentation illustrates the progress of an S-ISCO pilot test at the Bay Shore MGP site, Bay Shore, NY. The S-ISCO™ process underwent a successful large-scale field trial in Long Island, New York, in 2006 at a 125-yr-old former MGP site for coal tar DNAPL in residually saturated soils.
Technical and Regulatory Guidance for In Situ Chemical Oxidation of Contaminated Soil and Groundwater
Interstate Technology & Regulatory Council (ITRC). ISCO-1, 67 pp, 2001
Although this guidance has been superseded, Appendix B contains 8 case studies of ISCO implementation, 1 of them (p. B-12) at an MGP site in Long Beach, CA.
Abstracts of Journal Articles
Stabilizing the NAPL Threat: In-Situ Biogeochemical Stabilization and Flux Reduction Using Catalyzed Permanganate
J. Mueller, J. Moreno, M. Dingens, and P. Vella.
Pollution Engineering, Mar 2007
Creosote and pentachlorophenol were found over an 11,000 cu. meter volume in consolidated shallow alluvium deposit at an operating wood treatment facility in Denver, CO. Pilot-scale field studies of in situ biogeochemical stabilization (ISBS) were initiated in 2002 with the injection of ~24,050 gallons of a 3% aqueous potassium permanganate solution into 13 locations within a test area 75 ft by 95 ft by 10 ft deep. Over a period of 6 months, performance monitoring data showed rapid and complete stabilization of NAPL, contaminant mass reduction of 10 to 79%, and flux reduction of 56 to 99%. A full-scale application was approved in December 2003 and completed in May 2004, totaling 82,553 gallons of permanganate at 30 g/L (3%) in 44 injection points and 9,789 gallons in three trenches. The thickness of the NAPL layer decreased only in the monitoring piezometers located within the treatment area. Changes in NAPL thickness outside the treated area were not observed, suggesting that NAPL migration did not occur.
A chemical oxidation pilot test was conducted to determine the applicability and effectiveness of chemical oxidation in the creosote/pentachlorophenol source and dissolved plume areas. These treatability values have been used in groundwater computer model simulations to assist in determining if solidification and/or chemical oxidation and monitored natural attenuation will be cost-effective remedies. The ISCO pilot test was completed in October, 2005; the finial report, which also contained computer model simulations, was submitted to EPA in July 2006. Presently, EPA is evaluating all remedial alternatives to determine the most effective remedy, or remedial components, for the site.
Third Five-Year Review Report for Cabot/Koppers, Main St & 23rd Ave, Gainesville, Alachua County, Florida
U.S. EPA Region 4, 221 pp, 2011
Subject to acceptable performance demonstration during pilot tests or treatability studies, remedial components in EPA's 2011 ROD specify in situ geochemical stabilization (ISGS) of creosote source areas. Additional information: The initial ISGS demonstration workplan (dated 5/24/11) is available with other project documents in the Alachua County document database. Treatability study summary. ISGS white paper.
Abstracts of Journal Articles
Periodic Review: Dexter Horton Building, Facility Site ID#: 68766933, 710 2nd Avenue, Seattle, Washington
State of Washington, Northwest Region Office, Toxics Cleanup Program, 27 pp, 2011
ISCO treatment with hydrogen peroxide was conducted under the Dexter Horton Building to remediate soil contaminated with Bunker C fuel oil in July and August 2005. Subsequent soil sampling showed that the ISCO treatment had reduced TRPH concentrations in soil from a pre-injection concentration of 18,000 mg/kg TRPH to a post-injection concentration of 400 mg/kg. A "No Further Action" letter was issued February 16, 2006, with registration of a deed restriction owing to a small area of residual contamination that remains beneath the foundation.
Site Report for USCG MA6 DOT Building A-711
Alaska Department of Environmental Conservation, Contaminated Sites Database, 21 Feb 2007 Update
Contact: Jeff Brownlee, 907-269-3053, Jeff_Brownlee@dec.state.ak.us
A pilot study for the Building A-711 FUDS site on Kodiak was conducted in summer 2006 using a chemical oxidation technology—RegenOx®, a solid alkaline oxidant that employs a sodium percarbonate complex with a multi-part catalytic formula—to attempt to break down petroleum hydrocarbons consisting of DRO or FS-6 or Bunker C. Between 2,000 and 5,000 gallons of these hydrocarbons had leaked from an underground storage tank, resulting in the generation of a large heavy-end petroleum plume. Based on the pilot study report, Alaska DEC Contaminated Sites staff concluded that the method is not acceptable for this site because downgradient wells showed increases of benzene and some metals, indicating that the application was causing unacceptable increases of dissolved contaminants of concern. The total oxygen demand of the system was also greater than anticipated, indicating that the volume of oxygenate combined with the close spacing of injection points needed to treat the site to cleanup levels would be cost prohibitive.