Daniel Corkran, Ph.D., P.G.

Statewide Groundwater Flooding Assessment, Massachusetts — Developed a statewide groundwater-flow model using MODFLOW 6 to identify and assess groundwater flooding hazards across Massachusetts under current conditions and future climate and sea-level rise conditions. Performed sensitivity analysis, automated parameter estimation using PESTPP-IES, and uncertainty analysis. Performed a statewide normalized difference vegetation index (NDVI) analysis to assess forested wetland stress and wetland conversion under climate forcings.

Lithium Brine Mining, Salar del Hombre Muerto, Argentina — Conducted an environmental impact assessment for current and proposed lithium brine mines. Developed a 3-dimensional, variable-density, groundwater-flow model using MODFLOW 6 to evaluate the effects of fresh groundwater and brine abstraction on groundwater-dependent ecosystems. Collected streamflow measurements and surface water samples and installed transducers for long-term surface water monitoring.

Lithium Brine Mining, Argentina and Chile — Developed a series of 2-dimensional, variable-density, groundwater-flow models using SEAWAT. The three models were subbasin-scale, located in three endorheic basins in the South American Altiplano. The models evaluate the relative impacts of brine and freshwater abstraction on environmental flows to groundwater-dependent ecosystems across a series of hydrogeologic endmembers. Performed sensitivity analysis and uncertainty analysis. Performed an NDVI analysis of changes in vegetated wetland area at two wetlands adjacent to active lithium brine mining operations. Published results in a peer-reviewed scientific journal.

Former Petroleum Refineries, Pennsylvania — As project technical lead and deputy project manager, delineated residual and potentially mobile light nonaqueous-phase liquid (LNAPL) in soil and groundwater at two former petroleum refineries. Collected soil and groundwater samples and supervised high-resolution site characterization using a laser-induced fluorescence/ultraviolet optical screening tool and a hydraulic profiling tool to delineate LNAPL and identify preferential flow pathways in the subsurface. Developed a conceptual site model and utilized 3-dimensional geostatistical methods to estimate LNAPL volume and mass in the subsurface, differentiating mobile and immobile LNAPL. Oversaw nondestructive testing of foundations and retaining walls to evaluate structural stability and feasibility as flow barriers for LNAPL containment; analyzed and reported results. Conducted a feasibility study for the remediation of residual and potentially mobile LNAPL in soil and groundwater, evaluating permeable reactive barriers, injectable activated carbon, excavation, phytoremediation, and containment remedial actions. Pioneered the use of injectable activated carbon for residual LNAPL containment. Supervised and performed groundwater gauging, sampling, and groundwater mapping. Supervised monitoring well installations and well abandonments. Installed and maintained two phytoremediation barriers for petroleum constituents in groundwater. Oversaw excavations of soil impacted with PAHs, other petroleum constituents, and asbestos at former oil and gas wells and tank batteries. Collected confirmation samples and managed waste.

Former Weapons Manufacturer, Connecticut — Investigated chlorinated solvents and metals in stratified drift and fractured bedrock groundwater at a former weapons manufacturing site. Led and supervised slug testing, pump testing, borehole geophysics, and seismic surveys to evaluate preferential flow pathways for dense nonaqueous-phase liquid (DNAPL) migration and source area identification. Supervised well installation, and groundwater, soil, and sediment sampling. Developed site conceptual models, delineated plumes, and monitored natural attenuation.

Superfund NPL Site, Maryland — As project technical lead and deputy project manager, delineated metals and petroleum constituents in groundwater at a 5,000+ acre military base that is a Superfund NPL site. Supervised geophysical investigations using ground penetrating radar and electromagnetic surveys (EM31 and EM61) to identify source areas, including underground storage tanks and buried hazardous waste. Performed geochemical analyses in PHREEQC to differentiate naturally occurring sources of metals in groundwater from site releases, and environmental statistical analyses in ProUCL to identify background concentrations. Performed groundwater flow and contaminant transport modeling to support remedial investigation and delineation of heavy metals in groundwater. Supervised and performed surface water and groundwater sampling, groundwater gauging, drilling and installation of permanent and temporary monitoring wells, well surveys, and abandonments by three field teams working across 50+ areas of interest for site investigations and remedial investigations. Performed a preliminary site investigation for PFAS in groundwater, including collecting groundwater samples for PFAS. Oversaw excavations of soil contaminated with lead and other metals, and performed confirmation sampling with x-ray fluorescence. Also oversaw landfill containment berm and cap construction.

Aerospace Research and Development Facility, California — Developed a groundwater-flow model for groundwater pump and treat system optimization, fate and transport, and natural attenuation evaluation for chlorinated solvents in groundwater at an aerospace research and development facility.

Comprehensive Wastewater Management Plan, Massachusetts — Developed a citywide groundwater-flow model to evaluate potential threats to public water supply for the siting of wastewater discharge locations for a city. The modeling effort included MODFLOW-USG and MODFLOW 6 models; model domain, discretization, and boundary condition refinement; sensitivity analysis; automated parameter estimation using PESTPP-IES; uncertainty analysis; particle tracking, travel time analysis, and capture zone analysis using MODPATH 7.

Pond Eutrophication Assessment, Massachusetts — Developed a groundwater-flow model to assess nutrient loading and pond flow-through time to evaluate eutrophication and bacteria loading at a pond. The modeling effort included a MODFLOW 6 model, sensitivity analysis, parameter estimation using PESTPP-IES, and travel time analysis.

Ash Landfill Site, Maryland — Performed groundwater pump and treat system maintenance, troubleshooting of system failures, pump tests, and well reconditioning at an ash landfill site in Maryland. Conducted and analyzed step drawdown aquifer tests. Conducted surface and groundwater gauging and sampling. Developed database and reports for managing and analyzing long-term transducer data sets. Supervised private homeowner well disconnects and well reconditioning.

Retail Gas Station Portfolio, Maryland and Virginia — Oversaw operations and maintenance on groundwater pump and treat systems as well as soil vapor extraction systems, oversaw surfactant injections, performed carbon filter replacements, and maintained and installed LNAPL active and passive recovery systems at retail gas stations. Oversaw soil excavations and tank pulls; collected confirmation samples.

Steel Mill Groundwater Remediation and Monitoring, Maryland — Oversaw, maintained, and monitored groundwater remediation activities at a steel mill. Oversaw the installation and operations of an in situ bioremediation system for naphthalene in groundwater. Operated and maintained an LNAPL monitoring and recovery system and an air sparge/soil vapor extraction system. Supervised drilling and completion of monitoring, injection, and extraction wells, and conducted soil logging, soil sampling, and groundwater sampling. Compiled and managed database of boring logs and environmental data, including groundwater monitoring and laboratory analytical data.

Superfund NPL Site, Delaware — Delineated petroleum constituent and chlorinated solvent dissolved-phase and LNAPL plumes in groundwater at a Superfund NPL site. Prepared site conceptual models, including groundwater contour maps, groundwater flux calculations, contaminant plume isocontour maps, and natural attenuation assessment and monitoring. Oversaw, performed, and monitored in situ bioremediation for jet fuel and chlorinated solvent constituents in groundwater. Installed and maintained LNAPL recovery systems. Oversaw long-term groundwater monitoring activities for petroleum constituents and chlorinated solvents in groundwater. Oversaw drilling of temporary and permanent groundwater monitoring wells. Conducted and oversaw well surveys, groundwater monitoring, and groundwater and soil sampling.

Formerly Used Defense Site, Washington, DC — Delineated metals and perchlorate plumes and identified source areas for chemical weapons buried beneath homes and ambassadors’ residences in the District of Columbia. Prepared conceptual site models, including geologic cross-sections and groundwater flow nets. Supervised drilling of soil and bedrock borings, borehole geophysics, multiport well installation (FLUTe technology), hydraulic profiling, and packer testing for identification of flow pathways and plume delineation. Collected samples for isotopic analysis to identify chemical sources. Conducted groundwater, surface water, soil, and sediment sampling, and logged direct-push and bedrock boreholes. Worked in high-profile locations with public relations support for media coverage and international relations. Compiled and managed database of boring logs and environmental data, including groundwater monitoring and laboratory analytical data.

Long-Term Combined Sewer Overflow Control Project, Washington, DC — Conducted packer testing, slug testing, and drawdown testing at a citywide combined sewer overflow control project in Washington, DC. Analyzed testing data to determine aquifer properties and plan excavation dewatering activities for sewer construction in overburden and crystalline bedrock. Conducted well gauging, well surveys, and long-term groundwater monitoring with pressure and temperature transducers.

Hydroelectric Dam Stabilization, Iraq — Designed database and digital data collection forms for use in 24/7 drilling, borehole logging, and grouting operation at a destabilized hydroelectric dam in an active war zone. The operation to stop the dissolution of foundation materials beneath the dam required continuous, near real-time drilling and borehole log updates delivered to teams in Iraq and the United States.

Oil Refinery Environmental Monitoring and Remediation System Operations, Kansas — Developed digital data collection software and database for environmental site investigation, monitoring, and remediation system operations. Led pilot project at an oil refinery.

PFAS Preliminary Assessments, Nationwide — Developed digital data collection software and database for preliminary assessment data management and photographic logs. Led pilot project in Maryland, and expanded photo log software to nationwide portfolio of PFAS preliminary assessments for a federal client.

Retail Gas Station Portfolio, Michigan — Developed digital data collection software and database for environmental site inspection, investigation, and remediation system operations. Led rollout of pilot project across all retail gas station sites for a downstream oil and gas client.

Retail Gas Station Portfolio, Maryland, Virginia, Washington, DC, West Virginia, Pennsylvania, New Jersey, and New York — Conducted groundwater gauging, groundwater monitoring and sampling, well reconditioning, and well inspections; supervised drilling and completion of monitoring wells, well development, well abandonments, and well surveys for site investigations and remedial investigations at retail gas stations across Maryland, Virginia, Washington, DC, West Virginia, Pennsylvania, New Jersey, and New York.

Landfill Groundwater Monitoring and Plume Delineation, Maryland — Collected groundwater samples and supervised well installations for long-term groundwater monitoring and plume delineation at a landfill in Maryland.

Operational Range Assessments and Military Munitions Response Program, Maryland and Texas — Conducted composite surface soil and stream bed sampling for metals, perchlorate, and phosphorus associated with munitions at firing ranges on military bases in Maryland and Texas as part of a nationwide portfolio. Delineated impacted soil and sediment and oversaw remedial excavation and waste management.

PFAS Preliminary Assessment, Massachusetts — Performed a preliminary assessment for PFAS at a military base that is a Superfund NPL site in Massachusetts.

Marcellus Shale Oil and Gas Drilling Support, Pennsylvania and West Virginia — Performed mud logging and drill cutting analysis, monitoring and interpretation of real-time geophysical data from bottom-hole assemblies, monitoring and reporting of mud properties, identification of geologic formations, and geosteering for oil and gas well drilling and completion.