Education

-M.S. (Environmental Engineering Science) University of California, Berkeley, 1994
-B.S. (Chemistry and Biology) University of Arizona, 1991

Registrations/Certifications

Registered Professional Geologist, Arizona Registration No. 54327
OSHA 40-Hour Health and Safety Training for Hazardous Waste Operations, 1991

Representative Experience

• WQARF Site, Prescott, Arizona: Management of a remedial investigation (RI) of chlorinated VOCs in a colluvial and granitic bedrock aquifer system. Conceptual site model development of a complex hydrogeologic system. Activities included auger drilling in the alluvial aquifer with real-time groundwater sampling/analysis; sonic and air-rotary drilling in colluvium and fractured bedrock with real-time groundwater sampling; alluvial and nested well construction; aquifer testing for groundwater flow evaluation; groundwater sampling of monitoring wells; borehole geophysics; surface seismic geophysics; private well sampling; and soil vapor sampling for vapor intrusion evaluation with follow up indoor air sampling. A Land and Water Use Study (LWUS) was completed. The final RI report was completed in 2020 following public comment. A groundwater pumping pilot test, with carbon treatment and discharge of the waste stream, was completed in early 2020.

• WQARF Site, Cottonwood, Arizona: Management of an RI and ERAs involving two former dry cleaner sources in Cottonwood, Arizona. This Site has a dispersed VOC plume affecting private wells in a fractured limestone aquifer. Activities included alluvial and deep borehole drilling with real-time groundwater sampling/analysis to vertically delineate the PCE contamination; well installations; slug testing; extensive private well sampling; and extensive soil vapor sampling in the vicinity of the source areas. A vapor intrusion analysis of the results led to follow up indoor air sampling. The Draft RI report was completed in 2020. Granular activated carbon treatment systems were designed and installed as Early Response Actions at six private wells to remove chlorinated organic VOC contamination from drinking water.

• CERCLA Site, Tucson, Arizona: Management of remedial design/remedial action and hydrogeologic technical support and document review for CERCLA Site. The site has comingling plumes and multiple PRPs. Included technical meetings with EPA, ADEQ and Potentially Responsible Party consultants. This project included extensive review of groundwater flow and contaminant transport at five of the seven major project areas of the site, in addition to current and proposed groundwater remediation activities.

• Smelter Site, Patagonia, Arizona: Management of the investigation of lead and other metals contamination in soil of a site with lead slag waste from historical smelting activities. Investigation work included extensive x-ray fluorescence readings; and soil and groundwater sample collection and analysis. An Early Response Action (ERA) phase was performed to remove metals-contaminated soil, and therefore the potential dust inhalation hazard, from residential properties and import clean fill. A second ERA included the design and construction of a soil cover on several residential properties; construction of retaining walls and an infiltration basin; paving of a roadway with contaminated soil and slag; gravelling; riprapping; and additional soil/slag removal and clean backfill on residential properties.

• WQARF Site, Tucson, Arizona: Management of the investigation of metals contamination of a site with aluminum slag waste piles estimated at more than 6,600 tons. Investigation work included extensive x-ray fluorescence readings; soil and groundwater sample collection and analysis; a preliminary investigation report; and community involvement. An Early Response Action phase was performed to remove metals-contaminated soils from two residential properties and import clean fill. A berm was constructed for flood control and site grading and compaction was completed. Design and construction of a soil cover was completed as the remedial action. The Site was listed in the WQARF registry and an RI report was finalized. A feasibility study report was also prepared and finalized, along with a survey of site contamination and an Engineering Control Plan for the Declaration of Environmental Use Restriction. Soil cover inspection and maintenance activities have also been performed.

• Former Winslow Welding Site, Winslow, Arizona: Management of a corrective action LUST. Oversight and technical direction of field sampling activities and interpretation of data. A site characterization report was completed. Several separate excavations were completed to remove petroleum hydrocarbon contaminated soils. Technical input on soil vapor extraction (SVE) pilot tests. Direction and oversight of design, permitting and installation of a SVE remediation system with shallow horizontal collectors and GAC treatment. SVE system operation and maintenance is ongoing.

• Fluoride Investigation, San Simon, Arizona: Management of a project to evaluate a public water supply well impacted by high fluoride concentrations in San Simon, Arizona to determine source zones and make recommendations.

• Rio Salado Parkway Ventilation System, Tempe, Arizona: Management of the replacement of ventilation vaults for a ventilation blower system along the Rio Salado Parkway and Priest Avenue in Tempe, Arizona. The ventilation system was installed to ensure high-voltage electrical vaults were sufficiently vented to keep methane gas, produced by biodegradation of landfill waste, at less than explosive levels and to maintain oxygen levels at near atmospheric conditions. Performed locating and excavation services, mainly with a GapVax vacuum truck, to uncover the remaining pieces of vaults and riser pipe and then replaced/replumbed the vault and piping. Additional work may be performed in the future to uncover the main header pipe between electrical vaults and ensure that landfill settling has not affected the integrity of the vault system.

• Preliminary Investigation Sites, Arizona: Management of seven preliminary investigation projects, six of which will or have been listed in the WQARF registry due to exceedances of Aquifer Water Quality Standards or Soil Remediation Levels. Four of the sites involved chlorinated organics in groundwater. These projects included groundwater and soil sampling and reporting activities.

• WQARF Site, RI/FS, Tucson, Arizona: Management of the Remedial Investigation (RI) and Feasibility Study (FS) phases of a WQARF Site in Tucson, Arizona. The site has a 4,500-foot chlorinated ethene plume in perched groundwater and a large LNAPL body, mixed with chlorinated ethenes, constituting an ongoing source. Early Response Action remediation of the source area included SVE with vapor-phase GAC treatment. An air sparging pilot test was completed, indicating that the LNAPL could be successfully air sparged, in conjunction with SVE to remove contaminants. The following tasks/deliverables associated with the RI/FS phase included: groundwater and soil vapor monitoring well installations; groundwater and soil vapor sampling; soil gas investigation; RI/FS work plan; field sampling plan; QAPP; Land Use Study report; baseline Risk Assessment; RI report; FS report; and Proposed Remedial Action Plan.

• WQARF Site ERA, Tucson, Arizona: Management of O&M activities and planning for the installation of an SVE remediation system using existing SVE wells and plumbing. The SVE remediation system was designed to remove soil vapor contaminated with PCE, thereby removing any potential exposure from vapor intrusion. SVE remediation is ongoing. Soil vapor sampling and rebound testing is being conducted as part of the remediation activities. The 847 N Stone Ave property was a former dry cleaning facility and a separate release from the original WQARF site; this property was added to the WQARF site following approval of the original PRAP due to high soil vapor contamination.

• WQARF Site, Gilbert, Arizona, Town of Gilbert: Technical support for and review of a remedial investigation report for this WQARF site. Hydraulic conductivity estimation from slug testing data using aquifer test analysis software.

• Substation Spill Modeling in Mohave County, Tucson and Nogales, Arizona: Management of spill modeling project for small to large power generating stations for inclusion in SPCC plans. Project work has included: collection of field data; modeling of potential overland oil flow; production of site maps, data summary tables, and modeling results; and preparation of a brief site-specific report for each facility.

• Landfile Odors Invest, Sylmar, California: Management of a project involving characterization of landfill properties to understand and make recommendations to fix an odor issue at an active landfill in California. Project work included: installation of wells, and collection and analysis of baro-pneumatic and shut-in test data to evaluate the performance of the existing landfill gas control system (LFGCS) in controlling odors. The effect on the LFGCS of the current practice of adding a relatively thick daily cover material was additionally evaluated. The evaluation indicated that the cause of the odors was use of a cover material that was too permeable. Recommendations were made to test a spray-on alternative cover material.

• UST Removals: Management of an underground storage tank (UST) removal project for the Arizona DPS with three former fueling sites. UST closure assessment reports were completed and all three of the UST facilities were permanently closed. One of the sites required additional investigation.

• Public Works Yard, Winslow, Arizona: Management of a leaking underground storage tank corrective action site in Winslow, Arizona. Installed monitoring wells and soil vapor probes to characterize the site. Several separate excavations were completed to remove petroleum hydrocarbon contaminated soils. Prepared a site characterization report. Shallow SVE trenches and an SVE blower system with GAC treatment were installed and SVE remediation is ongoing. This site is currently in the ADEQ pre-approval program and LUST case closure is anticipated by 2021.

• Uranium Compliance Site, Arizona: Senior scientist evaluating compliance alternatives for uranium-impacted public water supply wells. Performed evaluation of uranium treatment alternatives.

• Geochemical Mining Projects, Arizona: Management of two geochemical projects (confidential client) for mine sites: an in situ bioremedial geochemical project and a heap leach neutralization project, both in the developmental stages.

• MEK Release Assessment and Remediation, Casa Grande, Arizona: Management of assessment and remediation of an MEK release at a manufacturing plant in Casa Grande, Arizona, under ADEQ's LUST program. Site characterization work included installation of wells, groundwater and soils sampling, and aquifer testing for hydraulic parameter estimation. Installation of a SVE/Thermal-Catalytic Oxidizer system for removal and treatment of explosive levels of MEK in the subsurface. Project included remedial soil vapor and groundwater data collection, groundwater monitoring and reporting, including MEK removal estimation. Completion of an ADEQ-approved Corrective Action Plan, Site Characterization Report and Corrective Action Completion Report for site closure. In the near future, 12 USTs for a tank farm at the site will be removed along with required soil investigation activities and the UST facility will be closed.

• Fueling Facility Phase III Study, Phoenix, Arizona: Management of a Phase III Pilot Scale Study and on-going remedial activities for cleanup of soils and groundwater impacted by LUST petroleum hydrocarbon contamination at West Sky Harbor Airport in Phoenix, Arizona. In addition to compliance with Remedial Action Objectives, project evaluated the effectiveness of bioventing, biosparging, nutrient addition, and anaerobic/aerobic cycling systems through extensive data collection, interpretation and reporting to the client and to ADEQ. Included recommendations for site-wide bioremedial technology.

• Fueling Facility, Phoenix, Arizona: Management of quarterly groundwater monitoring and reporting at West Sky Harbor Airport pursuant to ADEQ regulatory requirements. Management of vapor monitoring and reporting, and SVE oxidation system air quality monitoring and reporting pursuant to Maricopa County air quality permit requirements at the site.

• Harrison Road Landfill, Tucson, Arizona: Baro-pneumatic and pump tests for field air permeability and landfill gas generation measurements, plus well logging and drilling and installation oversight at a Tucson, Arizona landfill. Oversaw well lithologic logging, drilling, and well installation. Responsibilities included interpretation of soil gas analytical data, preparation of a landfill investigation report and presentation of findings to regulators. Project included deep soil vapor extraction (SVE) for protection and remediation of groundwater beneath arid landfills. SVE systems were configured to maximize removal of deep vadose zone volatile organic compounds (VOC) that had acted as a source to groundwater.

• Mine Site, Globe, Arizona: Management and execution of groundwater monitoring at a mine site in the Arizona WQARF program. Performed as part of Aquifer Protection Permit requirements.

• Chemical Manufacturing Facility, Livermore, California: Development and execution of a field investigation at a chemical plant that had been listed as an EPA Superfund site in Livermore, California. Performed Geoprobe soil gas and groundwater investigations, interpreted permeability and analytical data and wrote Site Cleanup Order recommendations for the client. Source areas included a UST/recycle pad.

• Mine Site, Globe, Arizona: Investigation of a deep bedrock aquifer at a mine site in Arizona. Sampled and tested new wells with a packer system and wrote up geochemical interpretation of findings. This project was part of the delineation of a very large high sulfate, high metals bearing groundwater plume within geologic formations having very different hydrologic properties.

• Engineered Earthen Cover, Casa Grande, Arizona: Execution of annual field inspections, maintenance and groundwater monitoring for an engineered earthen cover designed to protect groundwater and eliminate potential surface exposure from chromium-contaminated soils in Casa Grande, Arizona. Included annual reporting based on Consent Order requirements approved by ADEQ.

• Nitrate Loading, Kingman, Arizona: Completion of a nitrate loading paper study for a developer in Kingman, Arizona. Involved interpretation of available groundwater hydrogeologic and analytical data.

• Surface Water Investigation, Arizona: Perennial creek surface water investigation to evaluate the impact of an acidic mine originating groundwater plume. Included collection of surface flow and water quality data, as well as surface water samples.

• Mine Site, Globe, Arizona: Pit lake profiling studies with the collection of water samples and water quality data at various depths in a deep lake created by open-pit mining practices.

• Johnson and Ettinger modeling to evaluate the potential for subsurface vapor intrusion of chlorinated organics at a former manufacturing site in City of Industry, California.

• Estimation of GHG emissions and evaluation of Maricopa County monitoring obligations for landfills in Arizona pursuant to 2010 EPA reporting requirements.

• Estimation of landfill gas production using EPA’s LANDGEM model with appropriately chosen parameters, and waste disposal and human population data, for a closed municipal solid waste landfill in Spain.

• Involvement in a large-scale EPA mediation process with more than 20 sites contributing to VOC contamination in a single groundwater plume in the San Gabriel Valley, California. Evaluated sites with regard to source areas, contaminant definition and hydrogeology using site specific Information Briefs. Assisted in early cash out option comparison with client facility.

• Involvement in various groundwater and soils investigations including: historic chlorinated organic spills, placement of ORC socks in wells to prevent gasoline migration, highly acidic tailings piles, carbon dioxide concerns from acidic water reacting with aquifer carbonates, and benzene migration via natural gas release.

• As an analytical chemist, performed on-site analytical procedures for soil gas, groundwater, and soil investigations in mobile laboratory units using gas chromatography. Assisted with a field organic anion tracer injection, collected groundwater samples, and worked extensively with ion chromatography during a study at an EPA RCRA/CERCLA site.

SHORT COURSES:

UST and Water Quality Update Seminar, ENRS, State Bar of Arizona, 2004
RCRA Hazardous Waste Training, McCoy and Associates, 2004

PROFESSIONAL PUBLICATIONS:

Fischer, M.L., A.J. Bentley, et al. 1996. Factors Affecting Indoor Air Concentrations of VOCs at a Site of Subsurface Gasoline Contamination, Environ. Sci. Technol., 30, 2948-2957.

Sedlak, D.A., A.J. Bentley. 1997. The role of photochemistry in the transport and transformation of arsenic. Davis: University of California Water Resources Center, p. 13 (Technical completion report).

Haws, N.W., H.W. Bentley, A. Yiannakakis, A.J. Bentley and D. Cassidy. 2006. Stimulating in situ surfactant production to increase contaminant bioavailability and augment bioremediation of petroleum hydrocarbons. American Geophysical Union Fall Meeting, Dec. 11-15, 2006, San Francisco, California, USA. Oral Presentation (by Haws).