Remedial Optimization

Using Innovative Optimization Approaches for Successful Site Remediation and Long-Term Stewardship – Optimizing an environmental site cleanup achieves the ideal balance of protectiveness, cost reduction, remedy duration, and other objectives identified by stakeholders. Remedial optimization is a comprehensive process that provides viable results at the management and remedial strategy level, as well as specific improvements and efficiencies at the system level.

HGL’s remedial optimization subject matter experts (SMEs) have optimized site cleanup activities at hundreds of sites nationwide, improving protectiveness of the environment and saving over $100 million in operations costs. Our nationally prominent SMEs include a lead co-author of the Monitoring and Remediation Optimization System (MAROS) tool, which can be used to assess remedy performance and develop/implement an efficient long-term monitoring strategy by eliminating redundancies of well sampling. Our SMEs also include the lead author for a U.S. Environmental Protection Agency (EPA) document entitled A Systematic Approach for Evaluation of Capture Zones at Pump and Treat Systems. For over 15 years, HGL’s SMEs have been integral to the EPA’s nationwide optimization strategy for Superfund and National Priorities List (NPL) sites.

Additionally, HGL brings the following innovative decision-support optimization technologies:

  • PlumeSeekerTM – optimizes monitoring well networks to efficiently and accurately delineate contaminant plumes in groundwater and identifies the plume compliance boundary within a quantified confidence level.
  • Physics-Based Management Optimization (PBMOTM) – develops/optimizes pump-and-treat remedial design and operational approaches that lead to timely and cost-effective cleanups and successful long-term management strategies.

HGL has developed an integrated remedial optimization methodology that addresses sites from the initial investigation stage through long-term stewardship (LTS), remedy termination, property redevelopment, or anywhere in between. The HGL optimization approach relies on a thorough understanding of a site or its “conceptual site model” (CSM). HGL places the CSM at the core of its optimization process and incorporates broad ranging experience, specific technical expertise, fresh perspectives, high-level data analysis, and effective use of traditional and innovative tools. HGL’s approach is flexible and is modified as necessary to suit the needs of site stakeholders.

Whether applying optimization at a site managed by HGL or at another site as a third-party optimization provider, HGL’s optimization experts complete the following:

  • Review and identify data gaps in the existing CSM, and work with site managers to update the CSM;
  • Assess the condition and functionality of site infrastructure (e.g., existing monitoring wells, treatment systems) and current or forecasted cleanup costs;
  • Evaluate project objectives to determine if they are still valid and work with stakeholders to prioritize between competing objectives;
  • Identify key needs and constraints associated with meeting remedial objectives and evaluate potential options and technologies to satisfy those needs and address the constraints;
  • Evaluate remedy performance and make technical recommendations to improve remedy efficacy and cost efficiency;
  • Recommend efficiency improvements in energy and materials use;
  • Potentially use PBMOTM computational optimization technology to develop/optimize remedial design and operational approaches that will lead to timely and cost-effective cleanups and optimal long-term management strategies;
  • Develop a cost-effective site-specific strategy with short- and long-term recommendations; and
  • Develop/implement optimal strategies for attaining accelerated site closures (end-states) or property reuse and redevelopment.

HGL’s Multi-Level Remedial Optimization Services


This process is typically conducted through the three steps above. Among the benefits provided by this approach are the following:

  • An updated CSM or recommendations for obtaining information needed to update the CSM;
  • A determination of whether the existing remedial strategy is appropriate for the site based on the CSM and stakeholder objectives or a whether a modified remedial strategy is required;
  • Specific technical recommendations to improve remedy efficiency and effectiveness;
  • An opportunity to bring stakeholders together and form a consensus;
  • A team of experts familiar with the site who can be a resource on an as-needed basis; and
  • A starting point for preparing a Five-Year Review or for implementing Five-Year Review action items.

Project Examples:

U.S. EPA Superfund Optimization Projects, Nationwide

Former Hard Rock Mining Site in Idaho

Former Mercury Mining Site in California

HGL is contracted to conduct optimization reviews in support of EPA’s nationwide strategy to apply Superfund optimization practices at all stages of the CERCLA process, from site characterization through remedy implementation/operation and site completion. Each HGL review is an independent study funded by EPA that evaluates existing data, discusses the CSM, analyzes remedy performance, and provides suggestions for improving remedy efficacy, reducing costs, and achieving remedial action objectives, including site reuse and closure. Recommendations are based on an independent evaluation of existing site information, represent the technical views of the optimization review team, and are intended to help the site team identify opportunities for improvements in the current remediation strategy. Under multiple task orders, HGL SMEs have provided optimization reviews at over 40 sites nationwide, including mining sites, industrial sites, and landfills with a range of contaminants including chlorinated solvents, petroleum hydrocarbons, metals, polychlorinated biphenyl (PCBs), and 1,4-dioxane.

Project Highlights
For a 1,500-square-mile former hard rock mining site in Idaho, completed a large-scale monitoring optimization (soil, sediment, groundwater, surface water, biota) and developed recommendations including collecting filtered and unfiltered groundwater samples to adequately represent contaminants of concern (COC) transport and collecting and analyzing major ion parameters (calcium-carbonate, sodium-chloride).
For two former mercury mines in California, conducted an optimization review and identified several data gaps in the CSM, provided specific recommendations on how to address data deficiencies including establishing an online document repository, recommended additional surveying and structural evaluation of mine features and seep flow monitoring, and suggested an update to the CSM using additional biological sampling.
For a former wood treating facility in Arkansas, conducted an optimization review and recommended conducting additional site characterization to delineate source material and the dissolved-phase plume, installing additional groundwater wells to monitor contaminant attenuation and potential migration of contaminants, and implementing institutional controls.
For a 345-acre active landfill site in Washington where chlorinated solvent contamination in groundwater has extended off site, recommended conducting a survey to identify the status of all historical monitoring wells on site and exploring strategies for delisting the site and transferring regulatory oversight to a more appropriate regulatory framework, such as RCRA.



USACE, Kansas City District, Long-Term Remedial Action (LTRA) Contract

Under its LTRA contract, HGL provides remedial optimization services at a variety of sites. Environmental response actions include service and construction activities mandated by Superfund, the Formerly Utilized Sites Remedial Action Program (FUSRAP), and the Defense Environmental Restoration Program (DERP) at active Army and Air Force installations and at Formerly Used Defense Sites (FUDS). For a number of its projects, HGL has completed optimization studies to improve remedy efficiency, reduce costs, and achieve remedial action objectives, including site reuse and closure

Project Highlights
For the Nebraska Ordnance Plant site in Nebraska, optimized an inherited bioreduction and sodium acetate injection system with significant biofouling issues by scheduling periodic extraction well/injection well rehabilitation, pulsing the acetate injection and recirculation systems to inhibit microbial growth, and using pre-mixed acetate for a more homogenous substrate mixture.
For the Kings Mills U.S. Army Reserve Center in Ohio, inherited an inoperable dual-phase, high-vacuum extraction system and subsequently modified the piping so that the plant more effectively targeted volatile organic compounds (VOCs) and used HGL’s PBMOTM modeling tool to focus extraction, maximize contaminant removal, and ensure plume containment.
For the former South Jersey Clothing Co. and Garden State Cleaners Superfund sites in New Jersey, optimized the groundwater treatment systems by reallocating and balancing operator resources to reduce labor cost by 50%, upgrading the plant’s computer operating and SCADA/HMI systems to mitigate potential vulnerabilities, performing trend analyses in support of reducing sampling frequencies, conducting energy optimization studies, and providing annual cost estimates of system O&M and ancillary construction tasks.



Full-Service Optimization at the Former Fort Ord, CA

HGL optimized the design and operation of a groundwater remedial system at the former Fort Ord. As a result, the remedial goals for the site were met 3 years before the date estimated in the Record of Decision (ROD).
HGL employed an integrated approach to address the site’s technical and management complexities, which included the discovery that the trichloroethylene (TCE) contamination plume had extended off site approximately 1,400 feet beyond the previously estimated limit of 2,400 feet, the need to expand the existing remedial system, the presence of an adjacent carbon tetrachloride plume, and the existence of critical habitat. The integrated technical approach included the use of groundwater models, a cloud-based parallelized computational optimization methodology that used HGL’s PBMOTM tool, the ongoing adjustment of pumping schedules based on performance monitoring, and construction practices that minimized impacts on habitat. HGL achieved the groundwater remedial actions objectives in 2014, completed attainment monitoring in 2015, and obtained remedial action-completion concurrence from California regulatory agencies in 2016.

In April 2017, the American Academy of Environmental Engineers & Scientists® (AAEES) awarded HGL a grand prize for its work at the former Fort Ord. The Excellence in Environmental Engineering and ScienceTM competition has been identifying and rewarding the best in current environmental engineering and science since 1989.

Project Highlights
Recalibrated the groundwater flow and transport model developed during the remedial design phase to simulate the migration of TCE.
Used a groundwater model in conjunction with PBMOTM to evaluate alternative pumping strategies, including varied extraction rates and continual versus intermittent pumping at any combination of wells.
Conducted PBMOTM simulations that provided the basis for developing an optimized exit strategy that ensured that cleanup goals would be met in the most cost-effective manner and within the time period envisioned in the ROD.



Preparation of CERCLA Five-Year Review, DOE Pantex, Amarillo, TX

HGL prepared the second Five-Year Review (FYR) for the Pantex Plant under the CERCLA regulatory framework. The Pantex Plant is a high-profile U.S. Department of Energy (DOE) site in north Texas and the primary facility for assembly, evaluation, and maintenance of nuclear weapons in the U.S. The facility is overseen by DOE and the National Nuclear Security Administration (NNSA).

  • Historical waste practices resulted in 140 solid waste management units (SWMUs) containing metals, radionuclides, inorganics (e.g., perchlorate), VOCs, SVOCs, and various explosives such as RDX.
  • Plant discharges created a contaminant-containing large mound (16 billion gallons) of impacted perched groundwater at a depth of 250 to 300 feet.
  • Impacted groundwater lies about 150 feet above the Ogallala aquifer, the principal source of water for the City of Amarillo and agriculture in the region.

The project included a performance evaluation and optimization recommendations for multiple soil and groundwater remedies. Remedial actions were also evaluated for short- and long-term protectiveness. Primary constituents of concern at the facility include the high explosives TNT, RDX, and HMX; chlorinated VOCs such as TCE; hexavalent chromium; boron; perchlorate; and 1,4-dioxane.

Remedial components evaluated for performance, efficacy, and optimization opportunities included the following:

  • Two large-scale groundwater extraction and treatment systems addressing RDX, TNT, and associated metabolites as well as hexavalent chromium;
  • An in situ bioremediation (ISB) system treating RDX, HMX, TNT, and associated metabolites, as well as hexavalent chromium;
  • An ISB system treating TCE and perchlorate;
  • A soil vapor extraction (SVE) system; and
  • A landfill and soil covers.

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