Technology Innovation News Survey

U.S. Department of the Air Force, Air Force Installation and Mission Support Center, Joint Base San Antonio, Lackland, TX
Contract Opportunities on SAM.gov, Solicitation FA890323R0073, 2023

This is an 8(A) set-aside under NAICS code 562910. The U.S. Department of the Air Force requires a contractor to provide A-E Services for Air Force Civil Engineer Center (AFCEC) environmental projects at the former McClellan Air Force Base in California. Activities shall include: developing and updating plans that document the methods and procedures that will be used to conduct the remedial investigation including defining the nature and extent of PFAS contamination; collecting and analyzing geologic, geophysical, hydrogeological, ecological, chemical, physical, and hydrologic data; collecting and analyzing environmental samples such as groundwater, soil, surface water, sediment, tissue, and drinking water; managing and disposing of investigation-derived waste and other waste generated during the execution of the activities; refining the Conceptual Site Model using validated environmental data to identify migration and sample pathways by which populations may be exposed to contaminants; performing a source-strength assessment of PFAS-impacted vadose zone sources; conducting a CERCLA Baseline Risk Assessment to evaluate the risk to human health and the environment; conducting removal actions to respond to imminent threats to human health and the environment such as hot-spot soil removals; providing alternate water including bottled water and treatment systems; evaluating preliminary remedial alternative options to support remedial investigation (RI) scoping and response actions; designing and implementing interim remedial actions to manage/prevent migration of known contamination or stabilize the site; preparing CERCLA documents such as remedial investigation, time-critical removal actions, non-time-critical removal actions (Engineering Evaluation/Cost Analysis [EE/CA], Action Memorandum, and Workplan), and other decision documents such as an Explanation of Significant Differences, interim proposed plans and interim Record of Decision; supporting meetings such as public, stakeholder, and regulatory interface; updating the CERCLA administrative record and information repository with applicable work products and reports; and preparing and presenting expert testimony. Offers are due by 3:00 CDT on August 10, 2023. https://sam.gov/opp/89a5233fa5e448268bcfd26cda4fbe79/view

U.S. Department of the Air Force, Air Force Installation and Mission Support Center, Joint Base San Antonio, Lackland, TX
Contract Opportunities on SAM.gov, Solicitation FA890323R0092, 2023

NAICS: 562910. THIS IS AN 8(A) SET-ASIDE. The 772 Enterprise Sourcing Squadron (ESS) in conjunction with the Air Force Civil Engineer Center (AFCEC), Joint Base San Antonio - Lackland Air Force Base (AFB) in Texas, intends to award a Cost-Plus-Fixed-Fee (CPFF) contract to a Small Business 8(a) Architect-Engineer (A-E) firm to complete Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Remedial Investigations and Response Actions for Perfluorinated compounds (PFC) or Per-and polyfluoroalkyl substances (PFAS). The place of performance shall be at the Former England AFB, which is a Base Realignment and Closure faciity in Alexandria, Louisiana. Offers are due by 3:00 PM CDT on August 10, 2023. https://sam.gov/opp/f42e641758284edfa458684345d1fd66/view

U.S. Department of Agriculture Forest Service, Washington, DC
Contract Opportunities on SAM.gov, Solicitation 2970223R0014

This is a total small business set-aside under NAICS code 12970223R0014. The U.S. Forest Service requires a contractor to perform site environmental response activities including conducting various evaluations, studies, and reports as specified in the National Contingency Plan (NCP) found in 40 CFR 300 or as required by RCRA or other federal or state hazardous waste cleanup regulations. The Contractor may be requested to complete the following studies: Preliminary Assessment (PA), Site Inspection (SI), combined PA/SI, Risk Assessment, an Engineering Evaluation/Cost Analysis (EE/CA), a Remedial Investigation/Feasibility Study (RI/FS), or other documents required for CERCLA response actions, including CERCLA enforcement and litigation support. The Contractor may also be requested to implement the CERCLA site remedy in accordance with the NCP with approved work plans and decision documents or perform oversight of work being performed by responsible parties. Projects may be located anywhere throughout the USDA, Forest Service (FS), Pacific Southwest Region 5. Region 5 includes eighteen (18) National Forests, located primarily in California with some small acreage along the California/Nevada Border and the California/Oregon border. Some of the work may encompass private land adjacent to these National Forest lands. The Government anticipates awarding a multi-award Indefinite Delivery / Indefinite Quantity (IDIQ) Contract to four firms with a period of performance of one base year and four option years and an expected start date of September 1, 2023. Offers are due by 5:00 PM PDT on August 11, 2023. https://sam.gov/opp/4b6a0444f41d44cbbed519030f21e7a6/view

U.S. Environmental Protection Agency, Region 7 Contracting Office, Lenexa, KS
Contract Opportunities on SAM.gov, Solicitation 68HE0723R0047, 2023

This is a total small business set-aside under NAICS code 562910. EPA Region 7 requires the remediation of mine waste at Operable Unit 01 (OU1) of the Oronogo Duenweg Mining Belt (ODMB) Superfund site. The selected remedy for OU1 consists of excavation, consolidation, and disposal of mine waste and associated contaminated soil/sediments, property restoration, and revegetation. The site wastes will be consolidated and disposed of at existing onsite mine waste repositories. The Remedial Action (RA) will be conducted for EPA in accordance with the final plans and specifications developed during the Remedial Design (RD) and the Record of Decision (ROD) issued in June 2010, as amended in 2013, and the Explanation of Significant Differences (ESD) dated May 2016. For this solicitation, the term "mine waste" includes both visible mine waste (chat, tailings, and waste rock) and underlying soil/sediment contaminated with heavy metal concentrations exceeding the cleanup goals set forth in the Record of Decision. The award will be an Indefinite Delivery/Indefinite Quantity contract with fixed-unit prices consisting of a base period and four 12-month option periods. Offers are due by 2:00 PM CDT on August 15, 2023. https://sam.gov/opp/07c36ef6dc1341b2adb7e24362f300a1/view

Lyman, P.B. and R. Moore. ǀ 2023 Bioremediation Symposium Proceedings, 8-11 May, Austin, TX, 30 slides, 2023

Remediation is ongoing to clean up chlorinated solvents in groundwater from historical operations at Camp Grayling. Testing found PFAS commingled with a chlorinated solvent plume migrating toward the property boundary. An in situ reactive barrier consisting of colloidal activated carbon was installed, chosen because of the expected rapid PFAS reduction via removal from the dissolved mobile phase and well-established uses for chlorinated solvent sites. The project area was treated with a single application of colloidal activated carbon to address the contaminated groundwater. Mass flux and predictive competitive sorption modeling determined the appropriate amount of colloidal activated carbon. The solution was applied under low-pressure (non-fracking) conditions using direct-push technology with separate soil cores and monitoring well gauging to determine distribution. Before treatment, total PFAS levels detected in site groundwater samples were above the 70 ng/L EPA drinking water advisory limit. The mass flux and predictive competitive sorption modeling demonstrated a theoretical PFAS retardation span of over 50 years. Monitoring results demonstrated colloidal activated carbon distribution has been achieved using low-pressure injection methods. Furthermore, the post-application groundwater monitoring results demonstrated PFAS and chlorinated solvent concentrations were reduced to below Michigan's Drinking Water Standard within one month after the field activities and sustained for over four years.
Slides: https://www.battelle.org/docs/default-source/hidden/2023-bio-symp-presentations/track-b/b4_0800_85_moore.pptx.pdf?sfvrsn=1282caa3_3
Longer abstract: https://www.battelle.org/docs/default-source/hidden/2023-bio-symp-abstracts/85.pdf?sfvrsn=44f00225_3

Mora, R., J. Cuthbertson, J. Buzzell, S. Krenz, R. Moore, K. Gaskill, and A. Kavanaugh.

Elevated PFAS concentrations were identified (generally >10 ppb) in a shallow (0.5 to 3 ft bgs) perched aquifer at a former Fire Training Area with historic AFFF usage. The subsurface consists of a fairly permeable industrial fill and sand, underlain by a continuous clay layer. The remedial objective was to reduce PFAS groundwater concentrations migrating from the perched aquifer to a nearby surface water body. An in situ permeable treatment barrier was installed perpendicular to groundwater flow along the perimeter of the FTA, upgradient of the surface water body. A pilot study evaluated whether PlumeStop could be adequately distributed in the subsurface and effectively remove high PFAS concentrations from site groundwater. Based on the pilot study results, a full-scale PlumeStop remedy was designed and implemented. The full-scale approach consisted of injecting >292,000 lbs of PlumeStop into over 650 injection points to create a 1,625-ft-long barrier. PlumeStop loading in certain areas was modified based on the presence of co-contaminants. To date, this is the largest application of PlumeStop to treat PFAS-contaminated groundwater. Data collected during the pilot study indicated that PlumeStop could be distributed at least 4 ft radially away from each injection point. PFAS concentrations in groundwater (specifically PFOS and PFOA) were reduced by >99.5%. While performance monitoring data within the first 6 months showed significant (>99%) reductions in PFAS groundwater concentrations, additional localized injections were conducted to reinforce certain areas of the barrier where subsurface challenges had been encountered. The presentation includes more than 1.5 years of performance monitoring data from the full-scale implementation and predictive modeling results.
Slides:https://www.battelle.org/docs/default-source/hidden/2023-bio-symp-presentations/track-b/b4_0850_65_mora.pptx.pdf?sfvrsn=abb3453c_3
Longer abstract: https://www.battelle.org/docs/default-source/hidden/2023-bio-symp-abstracts/65.pdf?sfvrsn=35b668a8_3

Garza-Rubalcava, U., A.V. Smith, C. Thomas, M.A. Mills, W.A. Jackson, and D.D. Reible.
Environmental Pollution 328:121633(2023)

Coring and passive sampling tools were used to assess the transport and degradation of PAHs in an amended cap (sand + Organoclay® PM-199) in the Grand Calumet River during four sampling events from 2012 to 2019. Measurements of three PAHs (phenanthrene [Phe], pyrene [Pyr], and benzo[a]pyrene [BaP]) showed a difference of at least two orders of magnitude between bulk concentrations in the native sediments and the remediation cap. Average pore water measurements also showed lower levels in the cap respective to the native sediments by a factor of at least 7 for Phe and 3 for Pyr. Between the baseline (BL), which corresponds to observations from 2012 to 2014, and the measurements in 2019, there was a decrease in depth-averaged pore water concentrations of Phe (C₂₀₁₉/C_BL=0.20_-0.07^+0.12 in sediments and 0.27_-0.10^+0.15 in cap) and Pyr (C₂₀₁₉/C_BL=0.47_-0.12^+0.16 in sediments and 0.71_-0.20^+0.28 in the cap). No change was observed in native sediments (C₂₀₁₉/C_BL=1.0_-0.24^+0.32) for BaP in pore water and there was an increase in the cap (C₂₀₁₉/ C_BL=2.0_-0.54^+0.72). Inorganic anions and estimates of pore water velocity, along with measurements of PAHs, were used to model the fate and transport of contaminants and suggested that degradation of Phe (t_1/2=1.12_-0.11^+0.16 years) and Pyr (t_1/2=5.34_-1.8^+5.3 years) in the cap is faster than migration. Thus, the cap is expected to be protective of the sediment-water interface indefinitely for these constituents. No degradation was noted in BaP. The contaminant is expected to reach equilibrium in the capping layer over ~100 years if there is sufficient BaP mass in the sediments and no clean sediment deposition at the surface.

Quinnan J., J. McDonough, C. Theriault, D. Toase, and C. Morrell. ESTCP Project ER20-5258, 1,561 pp, 2022

A project was conducted at Eielson Air Force Base (AFB) in Fairbanks, Alaska to demonstrate and validate soil washing as a cost-effective mass removal technology to treat PFAS-impacted soil in source zones. The approach focused on treating coarse soil fractions and separating fines for potential treatment by other means, such as landfilling, thermal desorption, or stabilization. The goal was to optimize the treatment process to minimize wastes requiring more expensive treatment so that the cost would compete with landfilling. The treatment process was designed and optimized at bench-scale and demonstrated in the field through a treatment trial at the Eielson AFB using a mobile soil washing plant. Roughly 180 tons of PFAS-contaminated soil was treated from three stockpiles. Untreated PFOS concentrations ranged from 4.5 µg/kg to 560 µg/kg. The technology was validated by measuring PFAS mass removal efficiencies based on soil concentrations of PFAS compounds measured via DoD Quality Systems Manual 5.3 Table B-14 and PFAS leachate concentrations as measured by synthetic precipitation leaching procedure testing. PFAS concentrations in treated soils were compared to Alaska Department of Environmental Conservation screening levels for soil migrating to groundwater criteria for PFOA, PFOS, and PFBS. PFAS concentrations in soil leachate were compared to EPA groundwater screening criteria for PFOA, PFOS, and PFBS. Results confirmed that coarse-grained sand and gravel were successfully treated to meet performance goals, and the fines were segregated for alternative treatment. The reduction approach is a more cost-effective means that can be applied to treat most of the impacted soil volume while limiting expensive residual disposal or more expensive means of treatment, such as incineration or thermal desorption. Treated soil can be beneficially re-used onsite, and fines could be stabilized to meet leaching-based standards as an alternative to offsite disposal or treatment. https://serdp-estcp-storage.s3.us-gov-west-1.amazonaws.com/s3fs-public/2023-05/ER20-5258%20Final%20Report.pdf?VersionId=i0FwhbzRomdHlbr4zeCvD0LstilzHTYe
Executive Summary:https://serdp-estcp-storage.s3.us-gov-west-1.amazonaws.com/s3fs-public/2023-05/ER20-5258%20Executive%20Summary.pdf?VersionId=EGVCwrdEhQVmbvOLW_cbvc65ssnqm0q_
See YouTube video on the project: https://www.youtube.com/watch?v=iumX1HCbWMk

Feng, C., L. Kong, Y. Wang, A. Gu, and X. Huang.
Journal of Environmental Management 344:118583(2023)

Bench and field tests were conducted on a proposed novel multi-branch horizontal well in situ remediation process that integrates vertical/horizontal directional drilling, rotary injection, and expansion sealing techniques. The studies tested drilling tool performance, drilling accuracy, and injection radius of influence. Results showed that the supporting drilling tool met the process requirements and could complete multi-branch horizontal well remediation engineering construction. The deviation between the measured depth and the design depth of the horizontal well constructed using this technology was <9% and the deviation between the depth displayed by the guidance instrument and the measured depth was <1%. The injection radius of influence in the test field measured from the monitoring wells was ≥5 m. Results show that the process can provide an effective method to remediate contaminated sites. See the introduction and section snippets at https://www.sciencedirect.com/science/article/abs/pii/S0301479723013713

Wymore, R., E.C. Ashley, and N.Castonguay. ǀ 2023 Bioremediation Symposium Proceedings, 8-11 May, Austin, TX, 24 slides, 2023

High cis-DCE concentrations (270,000 µg/L) detected in an "upgradient" well to a municipal landfill initiated efforts to identify the source, characterize the plume, and generate a remedial strategy. Initial fracture mapping in exposed outcrops and a review of regional geologic structure informed the initial conceptual site model regarding bedrock fabric and potential preferential flow pathways and identified possible receptors. Bedrock monitoring well installation occurred in two phases: Phase I was informed by fracture patterns from the outcrop mapping and Phase II was based on downhole geophysics, hydraulic heads, and contaminant distribution. Characterization confirmed TCE DNAPL and identified offsite migration, resulting in assessment and mitigation. Boreholes were installed for pre-design characterization but also became part of the permeable reactive barrier (PRB). Injection testing was performed to assess substrate injection rates, and bench-scale testing established the optimum amendments for the PRB for chemical and biological reduction at the property boundary. For the bedrock pilot, permeability enhancement (hydraulic fracturing) delivered an amendment slurry of zero-valent iron, emulsified vegetable oil, and a sand proppant into seven existing fractures in three boreholes. Tiltmeter monitoring assessed fracture propagation and amendment distribution, and groundwater monitoring assessed performance. A separate pilot assessed amendment delivery in the overburden. Following pilot activities, a final remedial design was created for the PRB, which involves remediating the overburden and underlying bedrock. The amendment was distributed at least 20 ft from all fractures and up to 50 ft or more at some locations. Preliminary results show substantial increases in total organic carbon, the creation of strongly reducing conditions, and widespread VOC degradation within two months of amendment emplacement. The approach maximized the use of available information, performed work in structured phases, reassessed and updated the CSM throughout the process, and combined pre-design characterization with the installation of initial remedial infrastructure.
Slides: https://www.battelle.org/docs/default-source/hidden/2023-bio-symp-presentations/track-a/a3_1235_363_wymore_aurev.pptx.pdf?sfvrsn=62acf0af_3
Longer abstract: www.battelle.org/docs/default-source/hidden/2023-bio-symp-abstracts/363.pdf?sfvrsn=6ccf734a_3

Gutierrez, A.M., T.D. Dziubla, and J.Z. Hilt. ǀ Gels 9(4):344(2023)

Magnetic nanocomposite microparticle (MNM) gels were used as sorbents to remediate PCB 126 as a model organic contaminant. Three MNM systems used were curcumin multiacrylate MNMs (CMA MNMs), quercetin multiacrylate MNMs (QMA MNMs), and polyethylene glycol-400-dimethacrylate MNMs (PEG MNMs). The effect of ionic strength, water hardness, and pH on the sorption efficiency of the MNMs for PCB 126 was determined through equilibrium binding studies. The ionic strength and water hardness had a minimal effect on the MNM gel system. However, a decrease in binding was observed when the pH increased from 6.5 to 8.5, attributed to anion-π interactions between the buffer ions in solution and the PCB molecules and with the aromatic rings of the MNM gel systems. Results indicate that the developed MNM gels can be used as magnetic sorbents for PCBs in groundwater and surface water remediation, provided that the solution pH is controlled. This article is Open Access at https://www.mdpi.com/2310-2861/9/4/344

Ruyle, B.J., L. Schultes, D.M. Akob, C.R. Harris, M.M. Lorah, S. Vojta, J. Becanova, S. McCann, H.M. Pickard, A. Pearson, R. Lohmann, C.D. Veciti, and E.M. Sunderland
Environmental Science & Technology 57(14):5592-5602(2023)

This study reports the biotransformation of FHxSA, PFHxSAm, and PFHxSAmS C6 sulfonamido precursors in 3M AFFF with available commercial standards in microcosms representative of the groundwater/surface water boundary. Results show rapid (<1 day) biosorption to living cells by precursors but slow biotransformation into PFHxS (1-100 pM/day). The transformation pathway includes one or two nitrification steps supported by the detection of key intermediates using high-resolution mass spectrometry. Increasing nitrate concentrations and total abundance of nitrifying taxa occur in parallel with precursor biotransformation. Together, the data provide multiple lines of evidence supporting microbially limited biotransformation of C6 sulfonamido precursors involving ammonia-oxidizing archaea (Nitrososphaeria) and nitrite-oxidizing bacteria (Nitrospina). https://pubs.acs.org/doi/pdf/10.1021/acs.est.2c07178

Singh, A., R. Lynch, J. Solomon, J.D. Weaver, and A.R. May.
Journal of Hazardous Materials 448:130853(2023)

A study synthesized a library of 12 novel adsorbent materials that utilize a chemically well-defined silica support to remove PFAS from contaminated groundwater from a U.S. Air Force base. The library of sorbents probed the importance of fluorous, hydrophobic, and electrostatic components in removal efficacy. The materials were assessed in batch studies with PFOA, PFOS, and PFBA and compared directly to GAC and ion exchange resin. PFOS adsorption kinetics best fit a pseudo-second-order model and equilibrium data fit well to a Langmuir isotherm model. Results were also validated externally, and the best-performing material removed >90% of eight PFAS tested and could be regenerated up to 5 cycles. Results provide a top-performing material that, with further testing, can be used to clean up environmentally contaminated water. They also support the theory that a fluorous component, when combined with the electrostatic and hydrophobic components, imparts enhanced PFAS selectivity and functional resilience to the material.

Juhasz, A., M. Condina, and N. Kawashima. SERDP Project ER21-1059, 81 pp, 2022

The objective of this project was to gain an understanding of processes influencing the effectiveness of particulate amendments to treat groundwater contaminants in situ. Specifically, the project assessed whether contaminants sorbed to commercially available particulate activated carbon (PAC) were bioavailable for biodegradation and whether bacteria sorbed to PAC influenced sorptive capacity. ¹⁴C-Phenanthrene was used as a model compound to study biodegradation following sorption to PAC while ¹⁴C-PFOA was used to determine the influence of PAC-bacterial adhesion on contaminant sorption due to its limited biodegradation potential. A continuous flow method simulated contaminant transport and reactivity in model aquifers to which PAC was amended. ¹⁴C-compounds were introduced into PAC-amended model aquifers with effluent monitored to determine breakthrough and sorption capacity calculations. Bacterial influences were determined by introducing microorganisms into sterile PAC-amended aquifers pre- or post-14C-compound addition. In addition, matrix-PAC-bacterial interactions were visualized using environmental scanning electron microscopy (ESEM) and/or ToF-SIMS to provide complementary data regarding the distribution of PAC within the model aquifer and determine where/how bacteria were interacting with PAC, aquifer matrix, or the contaminant of concern. 14C-phenanthrene sorbed to the model aquifer material was readily mineralized by phenanthrene-degrading microorganisms. Although the model aquifer material had a low capacity to sorb phenanthrene, the desorbable nature of phenanthrene on the material rendered it available for biodegradation. PAC had a significantly greater capacity to sorb phenanthrene, however, PAC-sorbed phenanthrene had limited potential to desorb under flow cell conditions when the influent solution was modified. Introducing phenanthrene-degrading microorganisms into flow cells containing model aquifer material and phenanthrene-sorbed PAC resulted in limited phenanthrene mineralization, irrespective of phenanthrene loading onto the PAC. Assessing PAC using SEM identified that phenanthrene-degrading microorganisms were prevalent on PAC, illustrating that PAC-bacterial contact was not a limiting factor for the lack of phenanthrene mineralization. Although bacterial adhesion to PAC resulted in PFOA-PAC sorption variability (decreasing sorption with increasing biomass), there was no significant difference (p > 0.05) in maximum PFOA sorption when 104-109 cells/ml were introduced into the flow cell. https://serdp-estcp-storage.s3.us-gov-west-1.amazonaws.com/s3fs-public/2023-05/ER21-1059%20Final%20Report.pdf?VersionId=axS4kbTWYTJxY3p6kpjlE3BGOLE5Yobq

National Institute of Environmental Health Sciences, Superfund Research Program (SRP), June 2023

A new study shows exposure to PCBs through a mother's milk could cause short-term glucose intolerance in offspring. The study builds on earlier SRP-funded work by the same group that found connections between maternal PCB exposure and diabetes risk factors in progeny. Researchers aimed to understand how PCB exposure during nursing might affect glucose tolerance and body weight and composition in mice. The study focused on PCB126 and compared mice whose mothers had been treated with PCB126 on days 3, 10, and 17 after birth ~ with mice born to mothers treated with a harmless oil-based liquid. Pups in both groups were allowed to nurse until they were weaned at 3 weeks old. On the day of weaning, the team measured glucose tolerance in each group by administering sugar to the pups, then monitoring their blood glucose levels over two hours. The process was repeated every three weeks until the pups were 3 months old. The pups' body weight and body composition were recorded during the study period. Body composition measures - which included stored fat and lean mass, consisting of organs and muscles - provide more insight into diabetes risk than body weight. For instance, individuals with high fat and low lean mass may be more susceptible to hyperglycemia. The studies suggest that exposure to PCBs in utero, rather than during nursing, may cause longer-term and more damaging diabetes-related health effects in offspring. Nursing is a source of direct exposure to PCBs and can lead to short-term glucose intolerance, but the effects likely subside after weaning. https://tools.niehs.nih.gov/srp/1/ResearchBriefs/pdfs/SRP_ResearchBrief_342_508.pdf

Dunn, M., J. Becanova, J. Snook, B. Ruyle, and R. Lohmann.
ACS ES&T Water 3(2):332-341(2023)

The PFAS sampling rate, R_s, of a microporous polyethylene tube with a hydrophilic-lipophilic balance sorbent was predicted based on either partitioning and diffusion or solely diffusion. At 15°C, the lab-measured R_s for perfluorohexanoic acid of 100 ± 81 mL/day was better predicted by a partitioning and diffusion model (48 ± 1.8 mL/day) across 10-60 cm/s water flow speeds (15 ± 4.2 mL/day diffusion only). For perfluorohexane sulfonate, R_s at 15°C were similarly different (110 ± 60 mL/day measured, 120 ± 63 versus 12 ± 3.4 mL/day in respective models). R_s values from field deployments were in between these estimates (46 ± 40 mL/day for perfluorohexanoic acid). PFAS uptake was the same for previously biofouled membranes in the lab, suggesting the general applicability of the sampler in environmental conditions. Results demonstrate that the polyethylene tube's sampling rates were sensitive to the parameterization of the models used and partitioning-derived values should be applied.

Davis, E.L. EPA Publication EPA/600/R-23/062, 46 pp, 2023

In situ thermal remediation technologies rely on adding energy to the subsurface to change the phase distribution and other physical properties of volatile and semivolatile organic contaminants to mobilize them and aid in their recovery. The most used in situ thermal remediation technologies today are Steam Enhanced Extraction (SEE), electrical resistance heating (ERH), and thermal conductive heating (TCH; sometimes called in situ thermal desorption, ISTD). These three technologies are applicable to and have been proven for a wide variety of organic contaminants and in a wide variety of hydrogeologic settings, both above and below the water table. Thermal remediation technologies are very aggressive and are most applicable for contaminated sites (or portions of sites) where contaminant concentrations are the greatest, generally areas where nonaqueous phase liquids (NAPLs) are present. This paper briefly describes these commonly used in situ thermal remediation technologies and how they are deployed to remediate VOC and SVOC contaminated sites. Advice based on experience gained from sites where these technologies have been implemented is provided on soliciting thermal remediation services, how to determine the area/volume to be treated, and when to terminate the heating portion of the remediation. This paper includes both information gathered from other published papers and knowledge gained from the author's extensive experience of technical support for thermal remediation. https://cfpub.epa.gov/si/si_public_file_download.cfm?p_download_id=546981&Lab=CESER

Naval Facilities Engineering Command fact sheet, 6 pp, November 2022

Monitored natural attenuation (MNA) is a remedial option for monitoring the reduction of concentration, toxicity, and/or mobility of chemicals in groundwater. MNA can serve as a standalone remedy or be implemented as part of a treatment train through a transition from active treatment to a more passive treatment approach over time. Several lines of evidence are needed to achieve regulatory acceptance when selecting MNA as a primary remedy or transitioning to MNA as part of remedy optimization. This fact sheet shares lessons learned related to gathering robust lines of evidence to accelerate regulatory acceptance of MNA as a viable remedial approach. https://exwc.navfac.navy.mil/Portals/88/Documents/EXWC/Restoration/er_pdfs/r/Remedy%20Selection%20MNA%20Fact%20Sheet%20Nov%2021.pdf?ver=xe8BLvoR36AyAC_3eeEf5A%3D%3D

Werkema, Dale. ǀ 27th National Tanks Conference & Exposition, 13-15 September, Pittsburg, PA, 2022.

EPA developed the Environmental Geophysics website to bridge the gap between the basic science of geophysics and its application to environmental problems. The website contains geophysical resources, including an online textbook for geophysical methods relevant to environmental applications, a searchable list of current references, and geophysical terminology. Past and current EPA geophysical research and EPA-funded publications are provided. Geophysical tools, including decision support tools, miscellaneous geophysical utilities, and forward and inverse models are also available. The presentation highlights the free resources as a virtual environmental geophysics library and assists in guiding, selecting, and evaluating the applicability of geophysical methods to environmental objectives. http://neiwpcc.org/wp-content/uploads/2018/10/Werkema-Jr..pdf
The website is available at https://www.epa.gov/environmental-geophysics

Tobias, D. EPA Tools and Resources Webinar Series, 43 minutes, 2023

EPA committed in the agency's PFAS Strategic Roadmap to conduct a biosolids risk assessment for PFOA and PFOS in biosolids. In this webinar, EPA's Office of Water discuss the current work on assessing risk for PFOA and PFOS in biosolids that will serve as the basis to determine whether regulation of PFOA and PFOS is appropriate. The presentation covers the regulatory context through which EPA regulates chemical contaminants in biosolids, a brief overview of PFAS monitoring, and state actions. This is followed by a discussion of the exposure assessment framework EPA has developed to evaluate impacts from biosolids through ingestion of drinking water, crops, milk, and meat and how that framework may be implemented. https://www.epa.gov/research-states/epa-tools-and-resources-webinar-series

Hamper, M. and M. Seyedabbasi. ǀ Remediation 33(3):227-231(2023)

This work updates the 1970s oil spill model that described the infiltration of LNAPL into the subsurface, resulting in an oil pancake depressing the water table within the capillary fringe. The 1970s oil spill infiltration model describes that spilled LNAPL migrates downward through the vadose zone under the force of gravity with some lateral spreading. The vadose zone, where liquid pressures are less than atmospheric pressure, becomes a three-fluid zone consisting of variable saturations of air, water, and LNAPL, which fully saturate the pore spaces. One important update to the 1970s model is that instead of the infiltrating LNAPL stopping at and depressing the water table, LNAPL penetrates the water table to a depth consistent with the gravitational and capillary forces experienced during LNAPL infiltration and creates a two-fluid zone below the water table where LNAPL and water pressures are greater than atmospheric pressure. After the LNAPL release stops, LNAPL infiltration and migration will cease after reaching equilibrium. The updated LNAPL infiltration conceptual model, like the 1970s model, describes the situation where the LNAPL release has stopped and LNAPL infiltration and migration have ceased after reaching equilibrium. The volume of LNAPL released is also assumed to be sufficient to pass through the vadose zone and enter the saturated zone.