Subsurface treatment for targeted site impacts.
Some contamination can't be dug out or pumped away. What remains in the soil and groundwater after excavation and extraction requires a different approach. In-situ chemical injection delivers treatment amendments directly to the subsurface, addressing contamination where it sits without significant disturbance to the property or the operations running on it.
In-situ chemical injection works by mixing and injecting chemical amendments through a mobile unit connected to direct push points or existing monitoring wells. Before any injection begins, we assess site conditions to confirm that the subsurface chemistry, permeability, and contamination distribution are suitable for this approach. When the conditions are right, chemical injection remediation becomes one of the most direct paths to treatment.
After injection, we track the site's response through follow-up sampling and transparent reporting. The data shows whether treatment is progressing as planned, whether another round of in-situ injection is needed, or whether conditions have changed. In-situ injection can also be used alongside dual-phase extraction for sites where both free product removal and chemical treatment are needed at the same time.
One of the things that sets in-situ chemical injection apart from surface-based cleanup methods is that it can target contamination at depth that excavation simply can't reach. Once petroleum products or other organics have migrated below a building foundation, a paved surface, or utility infrastructure, digging becomes impractical. Injection reaches those areas through small-diameter points that don't require demolition or major site disruption. It's also repeatable. If concentrations rebound after an initial treatment round, a second injection event can be conducted using the same access points or adjusted locations based on what the monitoring data shows. The process is designed to be responsive to what the site is actually telling you.
Chemical injection remediation works best when it's part of a clearly planned strategy, not a last resort after other methods haven't delivered. When we assess a site as a good candidate early in the project, injection can often shorten the overall cleanup timeline considerably.
In-situ chemical injection delivers chemical amendments directly into the subsurface through injection points, where they react with contaminants in place. Rather than removing impacted material from the ground, this method brings the treatment to the contamination. It is used where excavation is impractical, where contamination is at depth, or where the volume of impacted material makes dig-and-haul remediation cost-prohibitive.
The amendment type depends on the contaminants present and the subsurface conditions. Common options include chemical oxidants such as sodium persulfate or hydrogen peroxide for direct destruction of petroleum hydrocarbons and other organics, oxygen-releasing compounds to stimulate aerobic biodegradation, and electron donors to support reductive processes for chlorinated compounds. Our team selects and mixes amendments on-site using our mobile injection unit.
We review existing site data including soil type, groundwater depth, hydraulic conductivity, contamination distribution, and chemistry. Permeable soils with moderate contamination concentrations and defined plume boundaries are generally good candidates. Sites with very low permeability, heterogeneous geology, or extremely high contaminant concentrations may require a different primary approach or a combination of methods.
In-situ chemical injection is effective against petroleum hydrocarbons, including BTEX compounds and TPH, as well as certain chlorinated solvents and other organic contaminants. The specific amendment and delivery strategy are matched to the target contaminants. At petroleum release sites, which are the most common site type we work on in Oklahoma, oxidant-based injection has a strong track record of reducing contaminant mass.
We collect groundwater samples from monitoring wells at defined intervals following injection, typically at 30, 60, and 90 days post-event and then on a longer schedule as conditions stabilize. The samples are analyzed for target contaminants and treatment-related parameters, and the results are compared to pre-injection baseline data. If concentrations are declining as expected, the program is working. If not, we evaluate whether a second injection round or a modified approach is warranted.
Yes, and it often should be. High vacuum extraction removes the recoverable free product from the water table, while in-situ injection targets the residual contamination that cannot be physically pumped out. Running both in sequence, or sometimes in parallel, addresses multiple phases of contamination and can reduce the total project timeline and cost compared to relying on either method alone.
Injection does not require open excavations, heavy equipment staging, or extended road closures. The work is done through small-diameter injection points that can typically be installed and used in a single day. Businesses and property operations can continue normally in most cases. This makes in-situ injection especially practical at commercial sites, fueling stations, and industrial facilities where shutting down operations is not a realistic option.
