EHC Slurry Injection in Downtown LA
- toddwhanna
- Oct 15
- 3 min read
Our team recently completed another successful Direct Push in-situ remediation project in Downtown Los Angeles, where we injected EHC® slurry and bioaugmented with Dehalococcoides (DHC).
Injection points were advanced using a Geoprobe® 6011 within parking spaces along a public street, requiring coordination with a traffic control contractor to ensure safe operations. At the end of each work shift, all equipment was removed from the site, and non-completed borings were temporarily patched to maintain site safety and accessibility.
The remediation remedy selected by our client was EHC ® ISCR Reagent, supplied by EVONIK in 50-pound bags.
For this project, the EHC® loading rate was approximately 50 pounds per vertical foot, which is the maximum dosage we typically recommend based on field experience. This rate ensures optimal subsurface distribution while preventing overloading of the treatment zone, which can lead to excessive surfacing or daylighting.
EHC ® ISCR Reagent is a finely milled proprietary blend of organic carbon, zero-valent iron (ZVI), and nutrients. This remediation technology is widely used for the effective treatment of chlorinated solvent contaminated groundwater, promoting long-term contaminant degradation through both abiotic and biotic processes.
The EHC material was mixed with water to create a 25–30% solids slurry, ensuring proper suspension of the solids and consistent distribution during injection.
All EHC mix water was prepared anaerobically onsite in two 330-gallon totes using an oxygen scavenger blend. This critical step helped create ideal conditions to support the bioaugmentation process using the Dehalococcoides (DHC) microbial culture.
The bioaugmentation process utilized Dehalococcoides (DHC) microbial culture to enhance site remediation and promote effective dechlorination.
Using our trailer-mounted measurement cylinders, we accurately measured and delivered the prescribed DHC dose. The culture was then injected in-line through our custom injection manifold, ensuring no oxygen exposure to the sensitive anaerobic microbes.
To maintain optimal anaerobic conditions, anaerobic flush water was injected before and after each DHC dose.
To reduce disruption to the tenant and nearby businesses, our team tucked our equipment within a service driveway behind temporary fencing. The only challenge with this setup was the need to run approximately 450 feet of high-pressure injection hose to reach the furthest injection location, a small tradeoff to maintain safe access and minimize our on-site footprint.
We utilized our retractable 2.25-inch slurry injection tools, designed with an internal conical cone that directs the slurry laterally through four discharge ports. The lower assembly point prevents downward migration and creates a packer-like sealing effect, ensuring effective reagent distribution within the targeted treatment zone.
The EHC® slurry was injected at a controlled rate of 10–20 gallons per minute (gpm). Injection flow rates and total volumes were continuously monitored and recorded using ultrasonic electromagnetic flow meters.
Injection pressure was monitored at both the injection manifold and the injection point, located up to 450 feet away. A pressure differential of up to 500 psi was observed between the manifold and the point of injection due to line loss. Injection pressures at the Injection Point ranged between 100 and 150 psi.
As a precautionary measure during injection operations, the nearby storm drain was sealed using plastic sheeting and sandbags to prevent any potential discharge. As with any injection event, particularly when injecting a solid slurry reagents, some surfacing or daylighting can occur.
Only minimal surfacing occurred on this project, demonstrating effective control and subsurface distribution.
Every Legacy project is guided by careful preparation, field precision, and teamwork. By combining proven chemistry with thoughtful application, we continue to deliver safe, efficient, and effective remediation solutions.
If you have any questions on this project, or if we can help support any of your current or upcoming projects, please contact us.
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