At the forefront of the groundwater industry for 45 years, SSP&A’s early work centered on the emerging environmental industry, where we provided expert services in support of high-visibility projects such as the Love Canal CERCLA site in New York. Over time, SSP&A took on projects involving a broader range of issues including water rights, soil and sediment contamination, surface water quality, saltwater intrusion, mining, landfills, and more recently, hydraulic fracturing (fracking) for natural gas and oil production.

With over a thousand projects completed throughout the United States and abroad, SSP&A assists federal, state, regional, and local agencies as well as private clients with:

• Regulatory issues, compliance, and negotiation;
• Resource evaluation and management;
• Expert testimony for litigation;
• Development, implementation and optimization of remedial measures for groundwater, soil, and sediment;
• Peer review and expert panel participation to address complex issues; and
• Technology transfer.

Our modeling and hydrogeology capabilities for water resources projects include:

• Aquifer hydraulics and analyses;
• Surface and groundwater assessments and modeling;
• Environmental and analytical geochemistry, and geochemical modeling;
• Statistics for environmental applications;
• Environmental engineering;
• Software development and computer programming;
• Database development, management, and data analyses;
• Field investigations; and
• Geographic Information Systems.

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Conjunctive-Use Management of Groundwater and Surface Water

SSP&A has firsthand experience in conjunctive-use management of groundwater and surface water that includes the analysis of water supply questions related to insuring delivery obligations set forth in interstate stream compacts in several Western States, including Kansas v. Colorado, the Lower Rio Grande projects, Kansas v. Nebraska and Nebraska v. Wyoming. SSP&A provides technical review of a proposed conjunctive-use projects, evaluation of surface water supplies available for basin recharge, capacity of the aquifer to store the recharged water, drawdown and stream depletion impacts of pumping stored water, and model suitability to forecast hydrologic conditions in various basins.

Many of SSP&A’s projects involve simulation of the interaction of groundwater and surface water features such as rivers, streams, ponds, and wetlands. The interaction of groundwater and surface water can be simulated in different ways depending on the site characteristics and the project objectives. SSP&A has reviewed, applied, or modified “off-the-shelf” public-domain codes (including the Stream (STR) package developed by Dave Prudic; the CLN package developed by Sorab Panday (Muffels, Panday, Andrews, Tonkin, and Spiliotopoulos, 2022, doi: 10.111/gwat.13202), MODBRANCH by USGS, HEC models developed by the U.S. Army Corps of Engineers Hydrologic Engineering Center, and others) for coupling of rivers to groundwater models, and has reviewed, modified, or used a variety of packages for river routing (including RiverWare, IGSM, CONSIM). Alternatively, SSP&A has simulated groundwater/surface systems using Fortran codes developed in-house for specialized cases. In these cases, SSP&A typically provides the Fortran code or models to clients for review and use.

Groundwater Flow and Transport Modeling

Groundwater flow and contaminant transport modeling form the cornerstone of our services. SSP&A staff members authored the premier reference for practicing hydrogeologists, environmental scientists, engineers, and graduate students (Applied Contaminant Transport Modeling: Theory and Practice, 1992, by Dr. Chunmiao Zheng). In 1998, the authors of the book were honored with the John Hem Excellence in Science and Engineering Award by the National Ground Water Association (NGWA).

PFAS Fate and Transport Assessments

Per- and Polyfluorinated Alkyl Substances (PFAS) constitute a class of thousands of persistent and mobile toxic chemicals that vary widely in their chemical and physical properties, and have been found to be ubiquitous in the environment. With the research and regulatory landscape for PFAS rapidly evolving, SSP&A collaborates with agencies and consultants to identify solutions to issues related to PFAS contamination in groundwater.

SSP&A is actively involved in the Interstate Technology Regulatory Council (ITRC) PFAS team by contributing to the ITRC guidance document and Fact Sheets for PFAS, as well as providing support for ITRC’s web-based PFAS expert roundtables. We are also involved in the National Ground Water Association (NGWA) PFAS task force.

Various clients retain SSP&A to assist with litigation matters regarding PFAS contamination at sites throughout the U.S., including states in the Mid-Atlantic, Northeast, Southeast, and Midwest.

SSP&A evaluates PFAS migration into groundwater via multiple pathways, including but not limited to air deposition of PFAS and subsequent infiltration through soils, direct releases from industrial activities, and land application of biosolids and treated wastewater. We provide technical expertise and expert testimony on the occurrence, attenuation, transformation, and transport of PFAS through various media (groundwater, soil, surface water, and sediments).

Technical evaluations have included the following:

Source Evaluation and Quantification

• Examination of the geochemical signature of PFAS contamination derived from manufacturing, and evaluation of downstream trends in PFAS surface water and sediment concentrations to determine PFAS loads and potential for attenuation in riverbed sediments.
• Geochemical fingerprinting of modern and historical aqueous film forming foam (AFFF) releases at a military facility.
• Analysis of ratios of different PFAS to differentiate industrial sources of PFAS to groundwater.
• Identification and quantification of waste streams from the electro-chemical fluorination (ECF) processes and assessment of which wastes are hazardous wastes.
• Assessment of PFAS background levels to provide context for evaluating sources.
• Detailed evaluations of nature and quantity of wastes containing PFAS produced at identified sites, disposal of these wastes, and migration of PFAS from disposal sites to groundwater and surface water.
• Review and compilation of chemical sales and purchase records of PFAS to constrain quantities of disposed PFAS waste.
• Assessment of the use of PFAS mist suppressants/wetting agents in hard chrome electroplating and determination of the likelihood of PFAS use at hard chrome electroplating facilities that operated prior to the promulgation of the National Emission Standards for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks Rule in 1995.

Fate and Transport Analysis

• Quantification of the volume of groundwater in aquifers impacted by PFAS contamination. This involved the development of a conceptual model of groundwater flow, compilation and spatial analysis of PFAS data to determine the area(s) of impact, evaluation of recharge rates to the aquifer for various recharge scenarios, and modeling changes in PFAS concentrations over several decades.
• Evaluation of the effect of physical, chemical, and biological processes on the long-term fate of PFAS in a shale bedrock environments.
• Assessment of degradation rates for both fluorinated side-chain polymer and non-polymer PFAS to reveal sources of PFAS in surface waters downstream of the contaminated site, and reveal potential issues for calculating mass balance for sites impacted by fluorinated side-chain polymers.
• Assessment of the transport of PFOA through the vadose zone and any subsequent mixing with groundwater.

PFAS Treatment Technology

• Evaluation of treatment costs for PFAS in wastewater and drinking water resources by implementing USEPA Drinking Water Treatment Technology Unit Cost Models.
• Research on novel treatment technologies
• Pilot studies comparing the cost-effectiveness and scalability of granular activated carbon (GAC), ion exchange (IX), and reverse osmosis (RO) technologies
• Review of other representative treatment systems.

PFAS treatment trains are assessed for systems at various scales, including residential households, local municipal water authorities, and site remediation systems.

Sampling and Analysis

• Groundwater and drinking water sampling for PFAS for litigation matters and for municipal evaluations of remediation options.
• Groundwater sampling for PFAS for various sites for Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) projects.
• Sampling of surface water and sediments for PFAS in support of Natural Resource Damages (NRD) litigation.

Relevant Projects