- Eliot Cooper

As exciting as new remediation technologies can be, most consultants want to implement solutions they know will work as described. Your clients won’t be impressed that you took a chance on something new—their main concern is if you achieved the results they hired you to get.

That’s why it’s so important to vet new treatment options before pulling the trigger. If you’ve been hearing a lot about automated injection technology, you’re probably curious (but understandably cautious).

In this blog post, we share the audience questions that remediation expert Eliot Cooper fielded during his recent webinar, The Droids You’re Looking For: The New Remediation Injection Technology and Automation Combatting PFAS and More. Consultants like you asked for information that would help them determine if and when utilizing the Pathfinder automated injection system would make sense for their projects.


Is the use of HRSC tools like MIHPT and WaterlooAPS a prerequisite to identify target transmissive zones before implementing the Pathfinder system?

I would highly recommend it. The goal of using the Pathfinder is to be very targeted in our injections, and ensure optimal distribution and contact time. If we don’t have a very clear idea of where contaminants are located in the subsurface, you may not see the gains you hoped to from using this system.


Are there space limitations? Or are there limitations on injection point spacing when using this system?

No. The Pathfinder system is flexible and adaptable to a wide range of injection site scenarios. Footprint or space/access limitations should not ever be an issue.


What is the additional cost of including Pathfinder relative to "traditional" injection?

There are two main ways we can look at the cost of an injection project and compare using Pathfinder to traditional injection techniques.

In the first scenario, we look at total lifecycle cost, where you get better distribution and contaminant contact with the Pathfinder. This significantly lowers overall project costs.

In the second scenario, we look at cost in terms of a daily rate. The use of automated injection results in some incremental cost increases over traditional systems, but the costs are not significant.


Did the regulatory agencies approve this new technology before it completed the first full scale project?

Yes, it was part of work plan that included sign-off by the appropriate regulatory agencies, so it’s unlikely there will be future issues. Better control over injections is a high priority for most relevant governing bodies. We’ve had really positive responses from water boards and regulatory groups where we’ve shared our technology.

A new amendment would merit a lot more scrutiny, but this is an automation and optimization of existing implementation technology, so the criteria for approval is different.


How does this in situ technology compare to other in situ technologies, such as thermal, in regard to performance?

Automated injection and thermal remediation are two really different applications. Thermal remediation is best suited for higher concentrations and source areas, and in a lot of cases it will be used on sites that are heterogeneous and tight soils. This application is more for dilute concentrations outside the source area—so it’s essentially comparing apples to oranges. They’re both useful technologies, but with separate best uses.


Is the goal of these techniques temporary mitigation or full remediation? Are the contaminants destroyed or impounded?

It depends on what we’re trying to address in the subsurface and what we’re injecting to do so.

If we’re injecting a treatment technology like an oxidant or a biosubstrate or reductant—the endgame there is cost effective reduction If we’re injecting activated carbon, then the endgame is going to be sequestration and some integrated treatment capability to meet MCLs

For PFAS, as an example, that application will strictly be to adsorb the contaminant and sequester it so it cannot be further spread.


What is the highest injection pressure the Pathfinder system can achieve?

It was designed to operate at a maximum pressure of 100 psi which is consistent with the remediation sweet spot we are targeting, e.g., transmissive zones.


What types of sites is it suited for? What types of sites or conditions are not as appropriate?

This technology is most suited for sites where we are trying to inject into a transmissive zone.

It can also be effective on some heterogeneous sites, where the design is to inject into a transmissive zone and have the chemistry persist there for a long enough time to address back diffusion.

Another suitable application is larger transmissive zones, where we can eliminate the flux coming off the site and possibly allow for turning off pump and treat systems.


How well does the magnetic flow meter works for slurries? Do you have a quality control procedure to determine if the presence of magnetic materials like ZVI affect the magnetic flow meter?

Yes, we do. We calibrate the meter based on the amendment so that should not impact the readings. The flow meters are very robust, and the design spec we provided to our equipment manufacturer included ZVI and other amendments.


How do you avoid corrosion and compatibility issues with automated injection systems that are injecting oxidants like peroxide or persulfate?

Everything is made out of stainless steel, except for our injection hoses, which are PVC.


Is pressure the only input that controls valve position, or if the design volume has been achieved at a specific injection point, would that injection point close while the injection continues to the remaining injection points until total design volume is delivered? Is there a set list of controls, or can these be modified from job to job?

With the Pathfinder, there is total volume cut off that ensures we don’t exceed the design amount for an individual injection location, and of course we control of injection pressure and flow.

Anything else where we have the capability to provide input into the system, we can control—temperature, pH, total dissolved solids, etc.


What are your thoughts about implementing automated injection system in weathered (fractured) rock aquifers with PFAS-contaminated conditions?

It depends on if the design is going to allow for low pressure injection. It would be specific to the formation. If it would high take pressure to get into a weathered rock, then we would recommend a traditional injection approach.


If you’d like to learn more about the Pathfinder, our automated injection technology, you can view our webinar on demand or download the technology overview.




Eliot Cooper, Vice President of Technology

Eliot Cooper

Vice President, Technology
[email protected]

Eliot Cooper is the Vice President of Technology and Business Development. In this role, he helps clients design efficient and cost-effective remedies using high resolution site characterization (HRSC) and a vast array of remediation options. His specialty is finding the right combination of tools and technologies for complex sites, and ensuring every step of the remediation process is optimized to achieve results.

Eliot draws on a career that spans more than 30 years in the environmental remediation industry and includes hundreds of projects nationwide. He’s remediated sites that involved hex chrome, fuel spills, and chlorinated solvents. He specializes in injected remedy delivery, remediation design support, characterization of VOCs, and tackling complex sites by combining multiple remediation technologies.

Eliot previously served at the Environmental Protection Agency in both air pollution and hazardous waste management programs, as well as in the private sector providing thermal combustion and in situ remediation field services. Eliot now leads Cascade's in situ remediation solutions team to evaluate available technologies to meet client goals, provide advanced delivery techniques, and ensure HRSC results in actionable solutions.

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