In Situ Chemical Oxidation
The injection of chemicals into the ground to reduce contaminants in groundwater has been successfully used for decades as an alternative to conventional technologies such as air sparging or pump and treat. However, the type of chemicals and delivery methods vary depending on the contaminants present and their location in the soil and the groundwater column. The methods of delivery may also vary depending on the site layout and subsurface characteristics.
The injection of strong chemical oxidizers, known as in situ chemical oxidation (ISCO), are most widely used as they are designed to treat a range of contaminants included petroleum, chlorinated solvents, and pesticides. The most common oxidants that are used for ISCO include permanganate, persulfate, and hydrogen peroxide. These oxidants are typically pumped into groundwater via injection wells, where they react chemically with contaminants producing harmless byproducts. The process works relatively quickly; the challenge is getting the reactants to the contaminant. Recirculating oxidant and groundwater between multiple wells improves the contact time and speed of treatment, particularly for large areas of contamination.
EnviroTrac’s professional team of engineers, scientists, and hydrogeologists, working with the product manufacturers, have the experience to design a custom treatment and delivery system. The system will be optimized for performance based on site conditions, contaminants present, subsurface characteristics, and hydrogeology. As a turnkey contractor, we employ professional staff to safely install, operate, and monitor the delivery system, including injection wells, chemical procurement, mixing, injection, and post injection monitoring.
EnviroTrac’s technicians are experienced in all fields of work, including installing wells for testing and injection, system piping, electronic controls, pumps, mixing tanks, system operation, recirculation, groundwater monitoring, and site restoration.
Discharging anything into groundwater will require interaction with one or more regulatory agencies. EnviroTrac’s long-term relationships with federal, state, and local agencies, along with experience navigating the rules and regulations pertinent to underground injection, will expedite the approval to utilize injection technology.
- Hydrogeologic testing
- Bench scale and field testing
- Full-scale design and construction
- Regulatory agency approvals
- Injection well installation
- Trenching and piping
- HDPE welding
- Chemical storage, handling, and mixing
- Secondary containment
- Delivery system controls
- Performance testing
- Groundwater monitoring
EnviroTrac was awarded a $10,000,000 contract with the New York State Department of Environmental Conservation for site remedial work under the State Superfund program at the former Pall Corporation and Photocircuits Site in Glen Cove, NY. The Pall Corporation historically manufactured filtration products at the site going back to 1946 and Photocircuits manufactured printed circuit boards. Chlorinated solvents were used by both entities in their manufacturing processes and released solvents formed a comingled plume impacting shallow and deep groundwater beneath the 5 acre Pall Corporation Site.
EnviroTrac installed a groundwater hydraulic control system that included extraction and re-injection wells, a collection trench, 57 chemical injection wells, process control enclosures, double-walled fused HDPE underground piping, piping vaults, along with performing all construction dewatering. Site challenges included coordinating construction while a self-storage facility was built on the property along with successfully maintaining safety around an operating daycare center located on the site. Safety operations included implementing an enhanced Community Air Monitoring Plan (CAMP) to monitor VOCs and dust during construction.
EnviroTrac began operating the large-scale injection system during the summer of 2021. The process included injecting base activated sodium persulfate using the system’s injection wells while extracting groundwater from a network of downgradient wells. Extracted groundwater was re-injected upgradient to increase the contact of the oxidant with the contaminants and provide hydraulic control. Multiple injections are performed as necessary to diminish the contaminant plume to meet remediation goals.