Integrating ISCO and ISS for Enhanced Soil and Groundwater Remediation

This White Paper examines the integration of In Situ Chemical Oxidation (ISCO) and In Situ Stabilization/Solidification (ISS) within a single remediation approach for contaminated soil and groundwater. ISCO applies powerful oxidants to degrade contaminants, while ISS immobilizes them within a stabilized soil matrix. Combining these technologies provides synergistic benefits, including reduced leachate concentrations, improved unconfined compressive strength (UCS), lower hydraulic conductivity (K), and minimized soil bulking.

The paper outlines key design considerations, performance data, and findings from Srivastava et al. (2016), demonstrating how this combined ISCO‑ISS strategy can deliver cost‑effective and sustainable remediation outcomes.

This White Paper examines the generation and management of sulfate residuals during the use of KLOZUR® activated persulfate for in‑situ chemical oxidation (ISCO). It explains how sulfate forms during contaminant oxidation, how elevated concentrations may influence groundwater quality, and what regulators typically consider when evaluating sulfate relative to secondary maximum contaminant levels (SMCL).

The paper also explores sulfate’s dual role in remediation: potential challenges for reductive dechlorination due to increased electron‑acceptor demand, and beneficial stimulation of anaerobic biodegradation of petroleum hydrocarbons through sulfate‑reducing bacteria (SRB). Design strategies such as lime activation to reduce soluble sulfate concentrations, as well as the concept of a combined remedy that leverages both ISCO and enhanced bioremediation, are discussed to support effective and sustainable site management.

This White Paper examines the challenges associated with 1,4‑dioxane—an emerging contaminant commonly found at chlorinated solvent sites—and explains why its high solubility, mobility, and persistence make it difficult to remediate. It summarizes key environmental and health considerations, along with the evolving regulatory landscape that is driving more rigorous monitoring and cleanup requirements.

Because conventional treatment technologies for dioxane are largely ex situ and often ineffective for groundwater, the paper highlights how KLOZUR® activated persulfate provides a powerful in‑situ chemical oxidation (ISCO) solution. The technology effectively destroys dioxane while simultaneously treating co‑contaminants such as TCA, DCA, and chlorinated ethenes, enabling a single, integrated remediation approach.

Laboratory and field results demonstrate the effectiveness of multiple activation methods—including heat, high pH, peroxide, and chelated iron—with case studies showing contaminant reductions of up to 99.9%.

This White Paper explains how KLOZUR® activated persulfate can be applied to remediate non‑aqueous phase liquids (NAPLs), one of the most persistent and technically challenging contaminant sources in soil and groundwater. It outlines the behavior of DNAPLs and LNAPLs, why they are difficult to locate and remove, and how incomplete treatment can lead to long‑term contaminant rebound.

The paper details key considerations for successful ISCO treatment, including oxidant contact, dosing requirements, and the influence of persulfate solution density on DNAPL and LNAPL targeting. It also reviews enhancement strategies—such as heat activation, hydrogen peroxide activation, high‑pH activation, and surfactant addition—that improve NAPL solubilization, desorption, and overall oxidant effectiveness.

By combining multiple activation approaches with KLOZUR® persulfate, remediation professionals can address petroleum hydrocarbons, chlorinated solvents, and mixed NAPL impacts more efficiently, supporting robust and sustainable site cleanup.

This White Paper examines the behavior of sulfate residuals generated during in situ chemical oxidation (ISCO) with KLOZUR® persulfate and provides updated insights into how sulfate evolves in groundwater after treatment. It summarizes laboratory and field evidence showing that sulfate levels typically rise within the injection zone immediately after persulfate application but generally return to baseline within six months. This decline is driven by natural processes such as dilution, dispersion, and microbial reduction by sulfate‑reducing bacteria (SRBs).

The paper also discusses secondary geochemical effects, including sulfide formation and the precipitation of metals such as mercury, which can further influence groundwater quality. Together, these findings offer a clearer understanding of sulfate attenuation mechanisms and support more informed design and evaluation of persulfate‑based ISCO remedies.

This White Paper examines how residual persulfate in groundwater samples can affect the accuracy of contaminant analysis following in situ chemical oxidation (ISCO) with KLOZUR® persulfate. While persulfate’s long subsurface persistence is a major advantage for treatment effectiveness, it can also lead to unintended reactions during sample transport or laboratory analysis—particularly under heated GC/MS or purge‑and‑trap conditions.

The paper reviews mechanisms that cause analytical bias, including continued contaminant oxidation during shipment and heat‑activated reactions during laboratory testing. It outlines practical strategies to minimize these effects, such as cooling and shielding samples during transport, reducing holding times, and using extraction methods to separate contaminants from residual oxidant. It also highlights research demonstrating that adding ascorbic acid can effectively stabilize samples by quenching sulfate radicals, significantly improving analytical reliability.

Together, these findings provide clear guidance for environmental professionals on how to manage persulfate‑impacted samples and ensure accurate groundwater monitoring results during ISCO projects.

This White Paper examines the use of electrical resistive heating (ERH) to thermally activate KLOZUR® persulfate for in situ chemical oxidation (ISCO). It explains how controlled thermal input accelerates sulfate radical formation at moderate subsurface temperatures and contrasts ERH with other activation methods such as high pH, metals, and hydrogen peroxide.

A large‑scale field project in the Seattle area demonstrates the effectiveness of this approach, where groundwater temperatures were elevated to 35–50 °C and more than 250,000 pounds of persulfate were injected to treat pentachlorophenol (PCP) in a petroleum hydrocarbon matrix.

Post‑treatment monitoring showed PCP concentrations reduced below cleanup levels with no rebound, highlighting ERH‑assisted persulfate activation as a powerful option for sites where thermal input can be applied efficiently and cost‑effectively.

This White Paper explores how compound‑specific isotope analysis (CSIA) enhances performance monitoring and project management for in situ chemical oxidation (ISCO). It explains how CSIA distinguishes true contaminant destruction from non‑destructive processes such as dilution, displacement, and rebound—limitations that often make concentration data alone misleading.

Drawing on field applications in New Jersey, Florida, and Switzerland, including sites treated with KLOZUR® CR, the paper demonstrates how isotopic fractionation data reveal treatment effectiveness, identify oxidant delivery limitations, and clarify rebound mechanisms. These insights enable more informed decision‑making, improve ISCO efficiency, and accelerate progress toward site closure.

This White Paper provides an overview of the Chemical Facility Anti‑Terrorism Standards (CFATS) and explains how these federal regulations affect the purchase, storage, and use of environmental remediation products. It summarizes DHS requirements related to Chemicals of Interest (COI), Screening Threshold Quantities (STQs), and the Top‑Screen reporting process, helping facilities understand when additional security assessments may be required.

The paper also clarifies that key remediation products—including KLOZUR® SP, KLOZUR® CR, PERMEOX® Ultra, and Dissolvine® E‑FE‑13—are not currently listed in Appendix A of CFATS, allowing them to be used without triggering CFATS reporting obligations. Guidance is also provided for facilities handling hydrogen peroxide, including when higher‑concentration formulations fall under CFATS due to their potential misuse as improvised explosive device precursors. Overall, the White Paper offers practical insight into regulatory compliance considerations for environmental products under CFATS.

This White Paper provides a comprehensive overview of methods used to detect and quantify persulfate in groundwater during in situ chemical oxidation (ISCO) projects. Because accurate measurement is essential for evaluating oxidant distribution, persistence, and treatment effectiveness, the paper examines both established and emerging analytical techniques. It reviews iron‑based titrations, iodometric reactions, and spectroscopic approaches, explaining how native metals, chelating agents, and co‑applied oxidants can interfere with results.

Practical field considerations are highlighted, including the use of KLOZUR® Persulfate Field Test Kits, qualitative starch–iodide screening, and secondary indicators such as conductivity and sulfate generation. The paper also introduces novel analytical concepts—such as indole and promethazine‑HCl colorimetric reactions and ion chromatography—that show promise for future field deployment.

Together, these insights equip remediation professionals with the knowledge needed to select reliable measurement strategies and improve monitoring of persulfate behavior in contaminated aquifers.

This White Paper introduces the concept of Natural Oxidant Interaction (NOI) as a more accurate framework for understanding how in situ chemical oxidants behave in uncontaminated subsurface environments. Moving beyond the traditional and often misapplied idea of natural oxidant demand (NOD), the paper explains how aquifer minerals, natural organic matter (NOM), and catalytic species influence oxidant persistence, decomposition rates, and treatment efficiency.

Drawing on extensive research from the University of Waterloo, it compares the NOI behavior of hydrogen peroxide, permanganate, and persulfate, highlighting their distinct reaction pathways, stability profiles, and interaction capacities. Bench‑scale and field data illustrate how factors such as amorphous iron content, NOM reactivity, and mineral catalysis shape oxidant longevity and consumption.

The paper underscores why quantifying NOI is essential for accurate oxidant dosing, realistic performance expectations, and cost‑effective ISCO system design—especially in heterogeneous aquifers where geochemical conditions vary significantly.

This White Paper provides a detailed explanation of Oxidation‑Reduction Potential (ORP) and its role in evaluating subsurface geochemistry during environmental remediation. It clarifies the electrochemical principles behind ORP measurements, including reference electrodes, half‑cell reactions, and the influence of pH, temperature, and redox‑active species.

The paper highlights common interferences—such as sulfides, organic matter, and metal ions—that can affect electrode performance and lead to misleading readings if not properly accounted for.

Practical guidance is provided for interpreting ORP in the context of bioremediation and chemical oxidation, including examples showing how ORP responds to changes in groundwater chemistry and why ORP must be evaluated alongside parameters such as pH, dissolved oxygen, and electron acceptor concentrations.

Together, the paper offers a clear framework for using ORP as a supporting tool to assess redox conditions and understand the chemical and biological processes influencing groundwater treatment.

This White Paper provides essential guidance on the safe handling, storage, and application of peroxygen‑based oxidants used in soil and groundwater remediation, including KLOZUR® activated persulfate, hydrogen peroxide, and PERMEOX® Ultra engineered calcium peroxide. It outlines the core safety principles—never contact, never contaminate, never confine, and always have water available—and explains how improper handling can lead to accelerated decomposition, heat generation, pressure buildup, or fire risk.

The paper highlights common hazards such as metal contamination, incompatible materials, inadequate ventilation, and improper storage temperatures, and offers practical recommendations for personal protective equipment (PPE), equipment selection, and field operations. Examples illustrate how pressure buildup in tanks or contact with combustible materials can create dangerous conditions if precautions are not followed.

Together, the paper serves as a comprehensive resource for environmental professionals seeking to manage peroxygen oxidants safely and in alignment with Responsible Care® principles.

This White Paper provides a clear, fact‑driven overview of the behavior and remediation challenges of chlorinated ethanes, with a focus on 1,1,1‑trichloroethane (TCA) in soil and groundwater. It explains why TCA’s physical and chemical properties—low solubility, high density, strong partitioning, and limited biodegradability—make it a persistent DNAPL contaminant requiring robust treatment strategies.

The document highlights proven in situ chemical oxidation (ISCO) approaches, including catalyzed hydrogen peroxide and alkaline activated persulfate, which have achieved up to 99.9% contaminant reduction in full‑scale applications. Remediation professionals gain practical insight into selecting the right oxidant system based on site conditions and performance goals.

This White Paper provides practical, data‑backed guidance for using KLOZUR® SP in ISCO treatment and in situ remediation, emphasizing its high solubility and ability to reach concentrations up to 40 wt% for flexible injection design. It highlights how concentration influences key performance parameters such as density, viscosity, and solution volume, including volume increases of more than 20% at higher wt%, which are critical for safe batching and tank headspace management.

Stability data show that mid‑range concentrations maintain excellent short‑term integrity, supporting reliable oxidant delivery during ISCO remediation. These insights help remediation professionals optimize in situ treatment strategies by selecting the right concentration, managing pore‑volume turnover, and ensuring safe, efficient handling of persulfate solutions.

This White Paper provides clear, data‑driven insight into how oxidant demand influences the performance and cost of ISCO treatment with KLOZUR® persulfate. It highlights that Soil Oxidant Demand (SOD) can exceed contaminant demand by a wide margin, especially in soils containing elevated organics or reduced metals, making it a critical factor in planning in situ remediation and determining chemical dosing.

The paper also outlines how persulfate lifetimes in the subsurface typically range from several weeks to several months, depending on pH, temperature, soil composition, and activation method—key considerations for achieving sufficient contact time and radius of influence in ISCO remediation. With practical guidance on TOD testing, treatability studies, and economic assessment, it supports remediation professionals in designing reliable, cost‑optimized in situ treatment strategies tailored to site‑specific oxidant demand.