Other Recent Additions
Recent Additions
Updated Focus Area: 1,4-Dioxane
Posted: October 2, 2018
The 1,4-Dioxane Focus Area has been updated to reflect the current state of the science, with an emphasis on the behavior, occurrence, site characterization and analytical methods, and treatment technologies sections.
Activated Carbon-Based Technology for In Situ Remediation Focus Area
Posted: August 14, 2018
Activated carbon (AC)-based technology involves emplacement of AC-based amendments for in situ remediation of soil and groundwater. Besides AC, amendments typically include other reactive products commonly used with in situ remediation technologies, such as in situ chemical reduction (ISCR), in situ chemical oxidation (ISCO), and bioremediation. The technology is commonly referred to as "carbon-based injectate" (CBI), especially for remediation of petroleum hydrocarbons. AC-based amendments remove contaminant via two processes: adsorption by AC and degradation by reactive amendments. The coupling of adsorption and degradation makes this technology a promising remedial option for addressing persistent plumes emanating from contaminants sorbed on soil, residual non-aqueous phase liquid (NAPL), or mass stored in low-permeability zones. The technology might also be applicable near or at the source area, especially when combined with other source treatment remedies, to limit contaminant mass flux out of source zones to downgradient plumes.
Remedial Technology Fact Sheet — Activated Carbon-Based Technology for In Situ Subsurface Remediation
Posted: August 7, 2018
This fact sheet concerns an emerging remedial technology that applies a combination of activated carbon (AC) and chemical and/or biological amendments for in situ remediation of soil and groundwater contaminated by organic contaminants, primarily petroleum hydrocarbons and chlorinated solvents. The technology typically is designed to carry out two contaminant removal processes: adsorption by AC and destruction by chemical and/or biological amendments. With the development of several commercially available AC-based products, this remedial technology has been applied with increasing frequency at contaminated sites across the country, including numerous leaking underground storage tank (LUST) and dry cleaner sites. It also has been recently applied at several Superfund sites, and federal facility sites that are not on the National Priorities List. This fact sheet provides information to practitioners and regulators for a better understanding of the science and current practice of AC-based remedial technologies for in situ applications.
Bisc Semi-Annual Monitoring and Performance Report, Rev. 1: July 1 to December 31, 2017, Perchlorate Bioremediation System, Henderson, Nevada
Posted: August 2, 2018
This monitoring and performance report for the perchlorate treatment system at Henderson, Nevada, documents groundwater monitoring and fluidized bed reactor (FBR) remediation system data collected July 1 through December 31, 2017, as well as results of the annual monitoring well sampling event. Groundwater treatment system operation is based at a 9,000 ft2 building located within a 1.77-acre site in Henderson. The FBR system began operation in late September 2012 and is designed to remove perchlorate from groundwater extracted from the Valley Auto Mall area (near the source area close to the former PEPCON facility) as well as the shallow groundwater bearing zone before it enters the Las Vegas Wash. The treatment system comprises 14 extraction wells, a water handling and FBR treatment plant, and a discharge system. The FBR plant consists of two first-stage FBRs that contain sand while a second-stage FBR contains granular activated carbon. Microorganisms growing as a film on the media utilize metabolic pathways to reduce perchlorate, chlorate, nitrate, and oxygen in redox reactions that result in nitrogen, CO2, water, and minerals. Ethanol is added as an electron donor along with nutrients (di-ammonium phosphate/urea mixture) and other trace elements. The pH is adjusted through the addition of a 50% (by weight) solution of sodium hydroxide.
Validation of Biotechnology for Quantifying the Abundance and Activity of Vinyl-Chloride Oxidizers in Contaminated Groundwater: Guidance Document
Posted: September 18, 2018
The purpose of this project was to evaluate qPCR-based molecular diagnostic tools for the purpose of estimating the attenuation contribution of VC-oxidizing bacteria. Groundwater and aquifer samples were taken from several DoD sites. The method targeted functional genes used by etheneotrophic bacteria in the aerobic VC biodegradation pathway. Functional genes associated with both VC oxidation and VC reduction were found present and expressed in groundwater samples. The researchers determined this by analyzing the relationships between functional genes associated with VC biodegradation and geochemical parameters, as well as the bulk VC attenuation rate at these contaminated sites. This novel technology promises to reveal the abundance and functionality of etheneotrophs at VC-contaminated sites. When this information is provided alongside a site-wide VC degradation rate, it could provide evidence that aerobic VC biodegradation is a significant contributor to overall VC natural attenuation processes.
Assessment of Post Remediation Performance of a Biobarrier Oxygen Injection System at a Methyl Tert-Butyl Ether (MTBE)-Contaminated Site, Marine Corps Base Camp Pendleton, San Diego, California
Posted: September 18, 2018
Project ER-201588 was conducted to evaluate the long-term performance of natural attenuation of MTBE after shutdown of a biobarrier system. The long-term impact of the biobarrier system on formation permeability was assessed via slug tests. In addition to evaluating data collected using conventional monitoring techniques, this project applied metagenomics and metaproteomics to improve the understanding of long-term impacts of the remedy on biodegradation at the site.
Long-Term Performance Assessment at a Highly Characterized and Instrumented DNAPL Source Area Following Bioaugmentation: ESTCP Cost and Performance Report
Posted: September 18, 2018
Monitoring was performed using soil sampling, passive flux meters, and push-pull tracer testing up to 3.7 years following active bioremediation of chlorinated ethene DNAPL source areas located at Alameda Point, Calif. Results showed that despite the absence of lactate, lactate fermentation transformation products, or hydrogen, biogeochemical conditions remained favorable for the reductive dechlorination of chlorinated ethenes. While ethene levels suggested relatively low dechlorination of the parent TCE and daughter products, compound-specific isotope analysis (CSIA) showed that the extent of complete dechlorination was much greater than indicated by ethene generation. Results of the push-pull tracer testing confirmed that DNAPL remained in a portion of the source area, consistent with soil and groundwater data. Reliance on ethene generation alone as an indicator of complete dechlorination significantly underestimated the extent of complete dechlorination, as CSIA analysis provided a more reliable estimate of dechlorination than reliance on ethene generation alone.
Sustained In Situ Chemical Oxidation (ISCO) of 1,4-Dioxane and Chlorinated VOCs Using Slow-Release Chemical Oxidant Cylinders
Posted: September 18, 2018
Slow-release chemical oxidant cylinders were applied to the treatment of a plume containing 1,4-dioxane and chlorinated VOCs (1,2-DCE, 1,1-DCA, cis-1,2-DCE, and TCE) in a technology demonstration conducted at Naval Air Station North Island, Calif. The objectives were to demonstrate and evaluate the technology's effectiveness, sustainability, longevity, oxidant transport and destruction, implementability, secondary water quality impacts, and technology reproducibility. Unactivated persulfate embedded in a slow-release paraffin wax formulation was emplaced in two 4-inch wells housed inside 18-inch diameter boreholes. The majority of the project's performance objectives were met. The oxidant cylinders are commercially available, but equipment for suspending cylinders in wells or reactive gates is not standardized and will require engineering design and possible custom fabrication.
Electrokinetic-Enhanced (Ek-Enhanced) Amendment Delivery for Remediation of Low Permeability and Heterogeneous Materials
Posted: September 18, 2018
Electrokinetic (EK)-enhanced amendment delivery for in situ bioremediation (EK-BIO) via enhanced reductive dechlorination of a PCE source area in clay was conducted at Naval Air Station Jacksonville, Florida. The EK-enhanced amendment delivery technology entails the establishment of an electric field in the subsurface using a network of electrodes. The electrical current and voltage gradient established across a direct-current electric field provide the driving force to transport remediation amendments, including electron donors, chemical oxidants, and even bacteria, through the subsurface. The EK demonstration system consisted of 9 electrode wells and 8 supply wells located within a target treatment area measuring ~40 ft by 40 ft. The remediation amendments distributed by the EK system included electron donor (lactate provided as potassium lactate), pH control reagents (potassium carbonate), and a dechlorinating microbial consortium (KB-1®) containing Dehalococcoides. Project results showed that EK achieved relatively uniform transport in low-permeability materials.
Advances in the State of the Practice for Enhanced In Situ Bioremediation
Posted: September 18, 2018
Enhanced in situ bioremediation (EISB) is an engineered technology that introduces physical, chemical, and biological changes to the aquifer to create the conditions necessary for microorganisms to transform contaminants of concern to innocuous byproducts. Recent innovations and trends to facilitate successful application are introduced. While this document discusses current industry-accepted best practices to design and apply EISB with a primary focus on chlorinated ethene remediation, it also discusses progress in identifying microorganisms capable of degrading 1,4-dioxane.
In-Situ Chromium Treatability Study Results Report, Nevada Environmental Response Trust Site, Henderson, Nevada: Revision 1
Posted: October 2, 2018
Separate field treatability studies were performed at the Trust site to evaluate biological and chemical reduction of Cr(VI) in the groundwater. For the biological reduction treatability study (Nov. 2016-Oct. 2017) in the Central Retention Basin, three separate substrate injection events were conducted to promote in situ biological reduction of Cr(VI). Carbon substrates injected over the three injection events included EOSPRO®, industrial sugar wastewater, granular sugar, and/or molasses. Monosodium orthophosphate (Aquapure 3601®) and a 39% solution urea/diammonium phosphate blend were injected as additional sources of phosphate and nitrogen nutrients. Sodium sulfite and ascorbic acid, both oxygen scavengers, were mixed with the substrate solution to promote anaerobic conditions prior to injecting. Sodium bicarbonate was also mixed with the substrate solution to adjust the pH as needed. Stabilized Lake Mead Water (SLMW), used as chase/flush water, was injected to enhance the carbon substrate distribution across the injection well network. For the chemical reduction study conducted August 7-8, 2017, the injection and monitoring wells installed as part of the Ammonium Perchlorate Area Up and Down Flushing Treatability Study were used for a single chemical injection event of a total of 600 gal of a calcium polysulfide (CPS) solution (60 gal of CPS and 540 gal of SLMW). The solution was injected across the shallow and intermediate injection wells associated with Plots 1 and 2 in the flushing treatability study area. A total of 3,910 gal of SLMW was injected as chase/flush water to enhance subsurface distribution. The findings of these treatability studies will be included in the feasibility study of remedial action alternatives to address Henderson legacy conditions.
A Practical Approach for Remediation Performance Assessment and Optimization at DNAPL Sites for Early Identification and Correction of Problems Considering Uncertainty
Posted: October 2, 2018
The objective of this project was to develop and test a methodology to periodically assess and optimize remediation and monitoring strategies at sites affected by DNAPL where remedies are in place. Methods were developed to model cost and performance of source zone and dissolved plume remediation technologies—including thermal treatment, chemical oxidation, enhanced bioremediation, and reactive barriers—and to optimize system operation and monitoring to meet user-defined cleanup criteria with minimum life-cycle cost, considering uncertainty in performance predictions using a stochastic optimization approach. The capability of the Stochastic Cost Optimization Toolkit (SCOToolkit) developed under SERDP Project ER-1611 was greatly extended in this project. The previous 2D contaminant transport model was rewritten to simulate 3D transport with steady-state groundwater flow along linear or curvilinear streamlines with multiple DNAPL sources.
Demonstration of Fluorescent Magnetic Particles for Linking Sources to Sediments at DOD Sites
Posted: October 2, 2018
Particle tracking offers a practical means to investigate source-sink relationships and map the transport pathways of contaminated sediments both at the point of and following delivery into waterways, through time and across space. This project demonstrated a particle tracking technology for quantitative mapping of the spatiotemporal distribution and depositional footprint of particles released from typical DoD contaminant sources into adjacent aquatic environments. Fluorescent ferromagnetic particles were released from specific sources, tracked through the water column, and collected at the sediment surface. The particles then were analyzed to determine their spatial distribution and depositional pattern and demonstrate quantitatively the linkage between sources and receiving water areas where the particle sources were most likely to impact the sediments.
White Paper On Thermal Remediation Technologies for Treatment of Chlorinated Solvents: Santa Susana Field Laboratory, Simi Valley, California
Posted: October 2, 2018
The objective of this white paper is to present information that will support the eventual evaluation of in situ thermal remediation (ISTR) to meet remedial objectives in selected areas of groundwater contamination at the Santa Susana Field Laboratory site. Corrective measures studies will be prepared separately by DOE, NASA, and Boeing for their respective areas of responsibility. The ultimate remedial objectives for the site are chlorinated solvent mass removal to a level that meets applicable state and federal risk-based groundwater standards. The ISTR evaluation consists of a comprehensive literature review focused on the application of ISTR to remove VOCs from bedrock sites. This paper is not intended to be a general review of all reported ISTR applications, nor does it provide details regarding ISTR system construction and operation. Rather, this paper summarizes the primary types of ISTR, discusses their effectiveness in reducing chlorinated VOC contamination in bedrock, and provides several specific examples of full-scale implementation.
Final Close-Out Report, Frontier Hard Chrome Superfund Site, Wad53614988, City of Vancouver, Clark County, Washington
Posted: October 18, 2018
Chromium, the hazardous substance of primary concern at the FHC site, is present in two forms, Cr(III) and Cr(VI). Although the 1987 OU-1 ROD called for excavation, stabilization, and replacement of all soils with concentrations greater than 550 mg/kg total Cr (~7,400 yd3 of soil) and the OU 2 ROD called for groundwater pump and treat from the area of greatest contamination (levels of Cr >50,000 µg/L), testing demonstrated the remedy would be insufficiently effective; hence, the remedy selected in the 2001 ROD Amendment was implemented in 2003. Injections of a blend of sodium dithionite and ferrous sulfate were performed to create an in situ redox manipulation (ISRM) treatment zone for the Cr-contaminated groundwater, followed by similar injections in source and hot spot areas. These treatments were effective. EPA issued a Notice of Deletion of the Frontier Hard Chrome Inc. Superfund Site from the National Priorities List on August 6, 2018.
