Other Recent Additions
Recent Additions
EPA Adds Subsurface Intrusion to the Superfund Hazard Ranking System
Posted: December 8, 2016
The U.S. EPA has finalized a proposal to expand the hazards that qualify sites for the Superfund National Priorities List (NPL). EPA assesses sites using the Hazard Ranking System (HRS), which quantifies negative impacts to air, groundwater, surface water and soil. Sites receiving HRS scores above a specific threshold can be proposed for placement on the NPL. Subsurface intrusion is the migration of hazardous substances, pollutants or contaminants from contaminated groundwater or soil into an overlying building. Subsurface intrusion can result in people being exposed to harmful levels of hazardous substances, which can raise the lifetime risk of cancer or chronic disease. This regulatory change does not affect the status of sites currently on or proposed to be added to the NPL. This modification only augments criteria for applying the HRS to sites being evaluated in the future.
Soil Dioxin Relative Bioavailability Assay Evaluation Framework
Posted: November 18, 2016
Until standard procedures for estimating the relative bioavailability (RBA) of PCDD/F in soil are established, there is a need for a consistent approach to evaluate the strengths and weaknesses of assays designs proposed or implemented to support risk assessments. This report offers a framework for making such evaluations. Specific design parameters that should be subject to evaluation are identified and relevant scientific literature is cited where more in-depth discussion can be found. Whenever possible, minimal requirements for study designs are proposed. This report also identifies issues that have yet to be resolved regarding how RBA assays should be designed and which could be objectives of further research to develop RBA assays for soil PCDD/F and applications to risk assessment.
State Vapor Intrusion Guidance Updates
Posted: November 18, 2016
- The Kansas Dept. of Health and Environment updated its 2007 VI guide with Kansas Vapor Intrusion Guidance (25 pp, 2016).
Passive Biobarrier for Treating Co-Mingled Perchlorate and Rdx in Groundwater at An Active Range
Posted: December 2, 2016
A field demonstration was undertaken to investigate the feasibility of using a passive emulsified oil biobarrier to remediate commingled perchlorate, RDX, and HMX in the naturally acidic groundwater at the Naval Surface Warfare Center, Dahlgren (Virginia). Microcosm studies indicated that a specific emulsified oil (EOS 550LS) plus a slow-release buffering agent (CoBupH) was the most effective substrate for promoting the biodegradation of all three target contaminants. Perchlorate degraded most quickly and HMX most slowly. After the second injection of emulsified oil, concentrations of RDX, HMX, and perchlorate fell by ≥92% in the centerline of monitoring wells extending 40 ft downgradient of the biobarrier. Accumulation of nitroso- degradation products from RDX was minimal. The biobarrier required no O&M other than injection/reinjection of oil substrate and had no impact on range activities.
Field Demonstration of Propane Biosparging for In Situ Remediation of N-Nitrosodimethylamine (Ndma) in Groundwater: ESTCP Cost and Performance Report
Posted: December 2, 2016
Propane gas and oxygen were added to groundwater via sparging to stimulate native microbes to biodegrade NDMA in situ at the Aerojet Superfund site in Rancho Cordova, Calif. Groundwater NDMA concentrations at the test site ranged from ~2,000 to >30,000 ng/L. The sparging system, which consisted of three biosparging wells connected to an air compressor and propane gas feed, supplied ~1.8 lb of propane to the in situ test plot per day for a period of 374 days. NDMA concentrations declined by >99.7% in the treatment area. A full-scale propane biosparge system was estimated to be ~40% less expensive to build, install, and operate than a comparable UV system over a 30-yr time frame.
Bioaugmentation for Aerobic Bioremediation of Rdx-Contaminated Groundwater
Posted: December 2, 2016
RDX is mobile and persistent in aerobic groundwater and typically forms large, dilute plumes that are difficult and costly to remediate using conventional technologies, such as pump and treat or anaerobic biostimulation. This project demonstrated an innovative application of bioaugmentation to enhance RDX biodegradation in contaminated groundwater under aerobic conditions at the Umatilla Chemical Depot (UMCD) in Umatilla, Oregon. The principal demonstration objectives were to (1) select and optimize RDX-degrading microbial cultures for use in aerobic bioaugmentation at the site; (2) compare in situ RDX biodegradation rates for aerobic bioaugmentation to those for biostimulation; and (3) quantify and compare costs of RDX remediation. This report summarizes the demonstration activities and results.
Nanofiber-Enabled, Multi-Target Passive Sampling Device for Determination of the Freely-Dissolved Sediment Pore Water Concentrations of Organic Contaminants
Posted: December 2, 2016
A suite of electrospun nanofiber mats (ENMs) was fabricated as next-generation multi-target passive samplers to test their sorption capacities for a set of hydrophilic (aniline and nitrobenzene) and hydrophobic compounds (PCBs and dioxin). The average diameter of the ENMs ranged from 70 (PET) to 1,000 (EVA) nm, with a relative standard deviation of less than 50% for each material. In water the ENMs yielded a fast equilibration time (<3 days) for the tested compounds. The ENM-water partition coefficient (KENM-w) for the hydrophilic compounds ranged from 0.72 to 2.8 log units. The KENM-w for hydrophobic compounds ranged from 3.2 to 6.4 log units. Collectively, the rates and KENM-w measured for the best performing ENMs often exceeded partition coefficients achieved with commercially available passive sampling materials (e.g., low-density polyethylene and PDMS glass fiber), particularly for hydrophilic compounds.
Third-Generation (3g) Site Characterization: Cryogenic Core Collection and High-Throughput Core Analysis, An Addendum to Basic Research Addressing Contaminants in Low Permeability Zones: a State of the Science Review
Posted: December 2, 2016
Core samples frozen in situ before recovery can preserve pore fluids, volatile compounds, dissolved gases, redox conditions, mineralogy, microbial ecology, and pore structure. Furthermore, in situ freezing improves the quality of recovered core by preventing materials from dropping out of sample liners during recovery to ground surface. The steps followed for collecting frozen cores are referred to in this text as cryogenic core collection. Processing core in the lab simplifies field work and improves the resources (e.g., anaerobic chambers) that can be used when preparing samples for analysis, while allowing "production line" processing and analysis of large quantities of samples (i.e., high-throughput core analysis). In this project, the combination of cryogenic core collection and high-throughput sampling yielded high quality samples suitable for a wide range of chemical, physical, and biological analyses of chlorinated solvents and other persistent contaminants in groundwater in unconsolidated sediments. The protocols for sample collection and processing are sufficiently robust that they can now be used routinely at field sites.
Voluntary Cleanup Report: Cross Manufacturing,, Inc., Lewis, Kansas
Posted: December 21, 2016
Past operations at the Cross plant included chrome plating. A voluntary cleanup in situ chromium reduction and fixation remedy was completed at the site between 2012 and 2015 to reduce Cr(VI) to the much less toxic and mobile Cr(III). This report describes the completed in situ Cr reduction and fixation remedy, performance monitoring, and site restoration activities. The remedy was completed by delivering the reducing agent calcium polysulfide through direct injection and amendment infiltration galleries, with treatments performed in October 2014 and May 2015.
Direct Push Optical Screening Tool for High-Resolution, Real-Time Mapping of Chlorinated Solvent DNAPL Architecture
Posted: December 21, 2016
This report describes the testing of a new direct-push optical screening tool for high-resolution 3D subsurface mapping of chlorinated solvent DNAPLs in unlithified sediments. The tool was field-tested at a formerly used defense facility in Massachusetts in fall 2013 (Geoprobe® delivery) and again in March 2014 (CPT delivery).The new tool, a laser-induced fluorescence (LIF) technology referred to as "DyeLIF™," was developed and validated during this project and is now commercially available.
Framework Guidance Manual for In Situ Wetland Restoration Demonstration
Posted: December 21, 2016
This manual is a guide to the use of in situ reactive amendment technologies for remediation of contaminated wetland hydric soils, providing a toolbox of methods with which to approach site characterization/monitoring, treatability testing and demonstration, and remedy implementation. This manual (1) provides a repository of literature sources for active in situ remedial projects; (2) outlines a conceptual approach to managing the remediation of wetland hydric soils; (3) offers suggestions for project objectives, metrics, and evaluation criteria; (4) discusses implementation means and methods; and (5) supports an assessment of technology cost. This guide is based upon a field demonstration conducted at Aberdeen Proving Ground to determine the most effective amendment to immobilize PCBs in wetland sediments among the following agents: powdered activated carbon slurry (Slurry Spray), two pelletized AC products (AquaBlok® and SediMite™), and an engineered manufactured soil cover system (sand control).
