Other Recent Additions
Recent Additions
Brownfields Road Map to Understanding Options for Site Investigation and Cleanup, Sixth Edition
Posted: February 27, 2018
The Brownfields Road Map 6th Edition breaks down Brownfields site investigation and cleanup into an easy to understand, step-by-step process that provides valuable and up-to-date information to a wide range of Brownfields stakeholders involved in or affected by the redevelopment of Brownfields sites. It introduces readers to a range of considerations and activities, and provides links to online technical resources and tools. The Road Map also highlights ten important issues, processes and initiatives commonly encountered by Brownfields stakeholders through "spotlights." These focus areas provide a quick look at topics currently relevant to Brownfields projects and provide links to additional information.
Steps Needed to Operate and Maintain the Sub-Slab Depressurization System Installed by EPA at the Chem-Fab Property
Posted: February 7, 2018
EPA installed a vapor mitigation system in the main commercial building at 300 N. Broad Street, Doylestown, Pennsylvania (part of the Chem-Fab Superfund Site) in response to the potential for an imminent and substantial endangerment to human health presented by the vaporous migration of benzene and chlorinated VOCs from soils beneath the building into office suites. The system draws sub-slab vapors from beneath the foundation using a system of fans and forces the vapors through PVC pipes into the air outside the building, where the vapors will not concentrate into unacceptable levels as they would in confined office space.
Demonstration and Validation of Enhanced Monitored Natural Recovery at DOD Sites
Posted: February 7, 2018
The performance of enhanced monitored natural recovery (EMNR) as an innovative and cost-effective remedy for legacy sediment contaminants was evaluated under field conditions at the Quantico Marine Corps Base, Quantico, Virginia. The sediments contained DDX (i.e., the sum of the pesticide DDT and it derivatives DDD and DDE). The remedy involved the placement of a thin-layer cap (TLC, commonly <30 cm, also referred to as a "habitat enhancement cap") of clean sand to enhance natural recovery and reduce contaminant bioavailability to benthic organisms and subsequent potential threats to higher trophic levels. While clean sand was used at Quantico Site 99, the caps can include a broader range of clean material, such as clean dredged sediment that meets the chemical criteria for reuse. This demonstration was designed to evaluate the performance and effectiveness of the Quantico EMNR remedy and the utility of available monitoring tools to address EMNR performance, short-term implementation success, projection of long-term remedy success, and understanding of the mechanisms and processes that regulate EMNR effectiveness. Overall performance objectives for cap placement and stability were met.
Cross Validation of Two Partitioning-Based Sampling Approaches in Mesocosms Containing PCB Contaminated Field Sediment, Biota, and Activated Carbon Amendment
Posted: February 7, 2018
This study compared two passive sampling-based approaches—(1) ex situ equilibrium sampling with multiple thicknesses of silicone and (2) in situ pre-equilibrium sampling with LDPE loaded with performance reference compounds—for measuring the bioavailable concentrations of PCBs in contaminated sediments. The study demonstrated that the two methods generated similar results. This information provides environmental managers with the ability to select between these two methods (depending on the circumstances) and know that the results will be comparable.
Advances in Sulfidation of Zerovalent Iron for Water Decontamination
Posted: February 20, 2018
Sulfidation has been shown to improve contaminant sequestration by zero-valent iron (ZVI). This review summarizes developments in ZVI sulfidation by describing the technology's progress through synthesis, characterization, and water remediation and treatment. Under most circumstances, sulfidation can enhance sequestration of various organic compounds and metal(loid)s by ZVI to varying extents. S-ZVI reactivity toward contaminants is strongly dependent on S/Fe molar ratio, sulfidation method, and solution chemistry. Sulfidation also can improve the selectivity of ZVI toward a targeted contaminant over water under anaerobic conditions. This summary includes a description of the mechanisms of sulfidation-induced improvement in contaminant sequestration by ZVI and identifies current knowledge gaps and future research needs of S-ZVI for environmental application.
Removal Action Completion Report: Electrical Resistance Heating in Source Area, Former Mercury Cleaners Site Area, 1419 16th Street, Sacramento, California
Posted: March 5, 2018
Mercury Cleaners operated as a dry cleaner from 1947 to 2014. The facility used a variety of dry cleaning solvents, and the site requires soil and groundwater treatment to remediate the impacts of petroleum-based Stoddard Solvent and of PCE and its daughter products. Cleanup began in 2015 with a soil vapor extraction (SVE) system pilot test, which is currently operating. To address soil contaminated with PCE above residential screening levels in an area ~40 ft by 40 ft in plan, a source area removal action was implemented in November 2016 using in situ electrical resistance heating (ERH) thermal desorption. Comprising 15 electrode/vapor recovery wells located within the source area, the ERH system was designed to volatize VOCs in the subsurface for SVE system removal and treatment. The goal of the removal action was to reduce contaminant mass by > 99% and lower concentrations of TPH, PCE, and other VOCs below the soil and groundwater cleanup goals. ERH system operation ended on July 7, 2017. Although source area cleanup goals were not met completely, significant PCE mass was removed from the source area.
Post-Remediation Evaluation of Evo Treatment: How Can We Improve Performance?
Posted: March 5, 2018
Enhanced reductive dechlorination (ERD) with emulsified vegetable oil (EVO) has been used at hundreds of sites to remediate chlorinated solvents, chromate, uranium, perchlorate, and explosive constituents. The process commonly involves injecting EVO, nutrients, pH buffer or base, and microbial cultures to adjust biogeochemical conditions in the immediate vicinity of the contaminant(s). Field, lab, and design evaluations of EVO use for TCE contamination at two sites at the former Naval Training Center Orlando are presented in this report. Although the remediation systems at both sites initially achieved substantial reductions in TCE concentrations, concentrations of cDCE and VC increased and remain elevated in some wells due to TCE degradation. Results from the project evaluations were used to identify the reasons for the ERD systems' failure to meet cleanup goals and to develop new approaches and procedures to improve performance.
Rapid Assessment of Remedial Effectiveness and Rebound in Fractured Bedrock
Posted: March 5, 2018
A rapid assessment (RA) protocol was developed in this project to assess the potential effectiveness of in situ treatment by chemical oxidation or bioaugmentation. The RA protocol is intended to assess chlorinated ethene rebound, the potential of naturally occurring dechlorination reactions in low permeability zones, and remedial effectiveness using a pair of closely spaced bedrock wells. The RA technique involves identifying hydraulically conductive fracture zones, flushing contaminant from the fracture zones using water, and then evaluating contaminant rebound within this zone while hydraulically isolating the zone from the surrounding contaminated aquifer. The rate, composition, and isotopic signature of contaminant rebound is then used to evaluate the limits of remedial effectiveness, identify the local source/cause of any observed rebound, and improve the site conceptual model. Work was performed at the former Naval Air Warfare Center (NAWC) in Trenton, New Jersey, as a preliminary test site to develop the methodology. The former Naval Construction Battalion Center (NCBC) Davisville (Calf Pasture Point) in North Kingston, Rhode Island, was used for more quantitative purposes and evaluation of the RA testing protocol during rapid flushing of a TCE-contaminated zone using water spiked with bromide tracer. Results from the second site are the focus of this report.
Groundwater Information Sheet: Methyl Tertiary-Butyl Ether (MTBE)
Posted: March 5, 2018
The information in this fact sheet was compiled by the staff of the Groundwater Ambient Monitoring and Assessment (GAMA) Program to provide general information regarding MTBE. The information was pulled from a variety of sources and relates mainly to drinking water. References are provided as sources of additional information.
Bay Road Holdings, East Palo Alto (Formerly Romic)
Posted: March 23, 2018
Bay Road Holdings LLC (formerly Romic Environmental Technologies Corp.) is a closed hazardous waste management facility located in East Palo Alto, Calif., near the San Francisco Bay. The facility ceased operations in 2007, and all surface structures were demolished in 2009. Historical facility operations from 1964 to 2007 included solvent recycling, fuel blending, wastewater treatment, and hazardous waste storage and treatment, resulting in releases that contaminated the soil and groundwater beneath the site. Biological treatment was the primary remedy selected by EPA to address the solvent-contaminated soil and groundwater. The biological treatment approach introduces a substrate (cheese whey and molasses were used in early testing) through horizontal injection wells (>200 ft long) for distribution via an in situ delivery (ISD™) groundwater recirculation system. The horizontal injection wells and the biological treatment system can operate independently and thus not interfere with the redevelopment ongoing at the surface. See details of this system in the ISD™ Groundwater Recirculation Pilot System Installation Work Plan at
Estimating the High-Arsenic Domestic-Well Population in the Conterminous United States
Posted: March 23, 2018
A logistic regression model of the probability of having arsenic >10 µg/L (high arsenic) in wells at the county, state, and national scales was developed using As concentrations from 20,450 U.S. domestic wells. The population in the conterminous U.S. using water from domestic wells with predicted As concentration >10 µg/L is 2.1 million people (95% CI is 1.5 to 2.9 million). Although some parts of the U.S. were underrepresented with As data, predictive variables available in national data sets were used to estimate high As in unsampled areas. By predicting to all of the conterminous U.S., the investigators were able to identify areas of high and low potential exposure in areas of limited As data, which can be viewed as potential areas to investigate further or to compare to more detailed local information. This paper is Open Access at
Rapid Assessment of Remedial Effectiveness and Rebound in Fractured Bedrock: ESTCP Cost and Performance Report
Posted: April 4, 2018
A demonstration of the rapid assessment protocol was performed in shallow bedrock at Calf Pasture Point in Rhode Island, where TCE was the primary groundwater contaminant. While nearly 99% of the TCE was removed from the conductive fracture zone during initial flushing, substantial contaminant rebound (up to ~5% of TCE baseline concentration) was observed over the 5-month rebound period. The rate and extent of observed contaminant rebound was reasonably described using a matrix back-diffusion model and CSIA, both serving as lines of evidence that the observed rebound was due to matrix back-diffusion. The back-diffusion model further predicted that over a decade of treatment likely would be needed to reduce TCE concentrations by 99% in the conductive fractures. CSIA testing not only served as a line of evidence demonstrating that the rock matrix was the source of the observed rebound but also confirmed the occurrence of abiotic dechlorination of TCE and DCE within the rock matrix.
Historical Releases of Mercury to Air, Land, and Water From Coal Combustion
Posted: April 4, 2018
Coal combustion is one of the largest contemporary sources of anthropogenic mercury (Hg). It releases geologically sequestered Hg to the atmosphere, and fly ash can contaminate terrestrial and aquatic systems. Coal combustion released an estimated cumulative total of 38.0 (14.8-98.9, 80% C.I.) Gg (gigagrams, 109 g or a thousand tonnes) of Hg to air, land, and water up to the year 2010, most of which (97%) occurred after 1850. The rate of release has grown by two orders of magnitude, from 0.01 Gg/yr in 1850 to 1 Gg/yr in 2010. Geographically, Asia and Europe each account for 32% of cumulative Hg releases and an additional 18% is from North America. About 26.3 (10.2-68.3) Gg or 71% of the total was emitted directly to the atmosphere, mostly from the industrial (45%) and power generation (36%) sectors, while the remainder was disposed of to land and water bodies. While Europe and North America were the major contributing regions until 1950, Asia has surpassed both in recent decades. By 2010, Asia was responsible for 69% of the total releases of Hg from coal combustion to the environment. Control technologies installed on major emitting sources capture mainly particulate and divalent Hg; hence, the fraction of elemental Hg in emissions from coal combustion has increased over time from 0.46 in 1850 to 0.61 in 2010. About 11.8 Gg of Hg or 31% of the total has been transferred to land and water bodies through disposal or utilization of Hg-containing combustion waste and collected fly ash/flue-gas desulfurization sludge; ~8.8 Gg of this Hg has simply been discarded to waste piles or ash ponds or rivers.
Developing Sediment Remediation Goals at Superfund Sites Based On Pore Water for the Protection of Benthic Organisms From Direct Toxicity to Nonionic Organic Contaminants
Posted: April 4, 2018
This document contains a methodology for developing and applying pore water remediation goals (RGs) for nonionic organic contaminants in sediments for the protection of benthic organisms. The text provides a technical approach and basis for setting the pore water RGs for contaminants in sediments. Contaminant concentrations in the sediment pore water measured using passive sampling directly incorporate bioavailability of the chemicals at the site into the development of site-specific sediment RGs. Also discussed is how to evaluate the consistency between passive sampling measurements and sediment toxicity testing results. When these data are consistent, there is reasonable assurance that the causes of toxicity to benthic organisms in the sediment have been correctly identified and that the developed pore water RGs for the contaminants will be protective of the site's benthic organisms.
Manufactured Gas Plant Remediation: a Case Study
Posted: April 4, 2018
The assessment, remediation, and redevelopment of manufactured gas plant (MGP) sites pose a significant technical and financial challenge to successor property owners, including municipalities and other public entities undertaking brownfields revitalization, and to their consulting environmental engineers. Due to the toxicity of many coal tar constituents, sites contaminated as a result of gasworks operations pose a significant threat to public health. The history of the manufactured gas industry in Massachusetts (the largest in the United States) is discussed, as well as the toxicity of gasworks waste products. The book then addresses the technical challenges in the MGP cleanup process, from site assessment, to remediation, to redevelopment. See a brief PDF preview of the book at
Status Report On Remedy Effectiveness: Hookston Station, Pleasant Hill, California
Posted: April 18, 2018
As detailed in this report, the Hookston Station parties have implemented several remedial actions to address environmental impacts associated with the presence of TCE and daughter products. Between 2008 and 2010, five in situ chemical oxidation injection events were implemented to remediate B-Zone groundwater. Performance monitoring showed successful distribution of potassium permanganate throughout the targeted treatment area. VOC concentrations in B-Zone wells within the core of the on-site source area are lower than pre-remediation results by up to two orders of magnitude. No additional ISCO injection events are needed. Since the installation in 2009 of a permeable reactive barrier (PRB) containing zero-valent iron to remediate A-Zone groundwater, TCE concentrations in groundwater have decreased significantly. Owing to the PRB's efficacy, only a handful of wells remain above the cleanup standards, and CVOC concentration trends in soil vapor are decreasing.
River Raisin Area of Concern: NAPL Area Remediation
Posted: April 18, 2018
The NAPL Area is defined as the portion of the River Raisin AOC that contains an apparent NAPL substance and concentrations of PCBs >50 ppm. Remediation activities performed in 2016-2017 within the NAPL Area consisted of dredging sediment containing PCBs to specified depths, followed by placement of cover material in the nearshore area or an engineered cap in other dredged areas. To sequester PCBs remaining in deeper subgrade materials in the NAPL Area, two types of multi-layered engineered caps (A and B) were placed on the post-dredge surface within the navigation channel and transition areas. The difference between Cap A and Cap B was the size of armor stone needed to protect the chemical containment layer. The cap profile consisted of a chemical layer (sand/organoclay mixture) to contain potential PCB transport from underlying materials, overlain by a gravel filter layer, and followed by the armor stone layer. The single chemical containment layer, 12 in deep, comprised 3% minimum organoclay mixed with sand. Decontamination and demobilization of materials and equipment commenced upon completion of dredging and capping.
Occurrence and Behavior of Per- and Polyfluoroalkyl Substances From Aqueous Film-Forming Foam in Groundwater Systems
Posted: April 18, 2018
Background is presented on aqueous film-forming foam and per- and polyfluoroalkyl substances (PFAS) source characteristics in Part 1 of this paper, including common industrial and consumer PFAS sources. Part 2 discusses chemical properties, sorption and retention parameters, observed transformation properties of PFAS and related compounds, and knowledge gaps. This paper is Open Access at
Evaluating Pfas Cross Contamination Issues
Posted: April 18, 2018
Due to the ubiquitous nature of per- and polyfluoroalkyl substances (PFASs) in commonly used sampling materials and personal protective equipment, mitigating the risk of cross contamination can be challenging when planning and executing a PFAS sampling program. This paper describes a conservative approach to PFAS sampling and includes an evaluation of three insect repellent products to determine their suitability for use during PFAS investigation. This paper is Open Access at
Technology Review and Evaluation of Different Chemical Oxidation Conditions On Treatability of Pfas
Posted: April 18, 2018
An overview of relevant literature summarizes the use of single or combined reagent chemical oxidation processes that offer insight into oxidation-reduction chemistries potentially capable of PFAS degradation. Based on the literature review, bench-scale treatability tests were designed and performed to establish optimal conditions for the formation of specific free radical species, including superoxide and sulfate radicals, using varied combinations of oxidants, catalysts, pH buffers, and heat to assess PFAS treatment by chemical oxidants. This paper is Open Access at
Integrating Total Oxidizable Precursor Assay Data to Evaluate Fate and Transport of Pfass
Posted: April 18, 2018
Current commercial laboratory methodologies primarily quantify between 14 and 31 per- and polyfluoroalkyl substances. As an alternative, a total oxidizable precursor assay (TOPA) was developed to quantify measurable concentrations of perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs) after aggressive oxidation to convert perfluoroalkyl acid (PFAA) precursors abiotically into PFCAs. This paper discusses the potential application of this approach to characterize PFAS contamination. This paper is Open Access at
In-Situ Remediation of Arsenic-Contaminated Sites
Posted: April 18, 2018
This text provides scientific background, case studies, and future perspectives of in situ arsenic remediation technologies for soils and groundwater at geogenic and anthropogenic As-contaminated sites. Natural arsenic (arsenate and arsenite) as well as organic arsenic compounds are discussed. Technologies covered include geochemical, microbiological, and plant-based ecological solutions for arsenic remediation. View the table of contents at
