Endophyte Assisted Remediation

Intrinsyx Environmental has been working in Alaska since 2018, and our process was analyzed and approved by the Alaska Department of Environmental Conservation. After our initial results were examined, the project was expanded, and other departments like the Alaska Department of Natural Resources and the Alaska Department of Transportation and Public Facilities also support our process.

Conventional remediation can be expensive and demands energy needs that many communities cannot afford or supply. Our approach takes advantage of solar powered systems and local native tree and plant species, creating functional green space for local communities.

Case Study: FAI Airport

Our process can work with individual or mixed-waste contaminants. As an example, we currently have a project at the Fairbanks International Airport, where the soil and groundwater contain diesel, gasoline, benzene, and 1,2-dichloroethane at concentrations exceeding 200 milligrams per liter. This site occupies roughly 3 acres and previously contained warehouses, offices, six above-ground storage tanks, a pump building, and a truck loading rack. Fuels were shipped and received between 1974 and 1997 using a rail loading rack. In 2015, the above-ground infrastructure, above-ground storage tanks, and truck loading rack were removed and a pump-and-treat system was relocated near the air sparge building.

The site is near the Chena River, and the region includes undeveloped forested land, low-density residential properties, and light industrial properties. The primary contaminated area was built on several feet of sand and gravel fill before being paved. The native soils beneath contain sediment from the Tanana and Chena River Flood Plain and are mostly silt and sandy silt present from 3 to 19 feet. Groundwater in this region occurs under unconfined and confined conditions, with the water table averaging 5 to 12 feet below ground surface. Groundwater flow beneath the site has low gradients.

Previous and ongoing treatments at this site have included an enhanced anaerobic bioremediation pilot in 2002, installation and operation of a twenty-seven-well air sparging system, and a pump-and-treat remediation system constructed in 2010 (no longer active). In total, thirty-nine wells were installed for air sparging. In 2018, an additional ten bioventing wells were installed in the rail loading rack to promote bioremediation.

The remedial objective of this site is to decrease the concentrations of contaminants in the groundwater to acceptable levels based on State of Alaska and US Environmental Protection Agency regulations. Remediation of the site and the surrounding affected area will continue until the concentration levels are acceptable. The main objective was to reduce the 1,2-dichloroethane source zone and help control off-site migration. The secondary objective was the degradation and migration control of benzene, toluene, ethylbenzene, xylene compounds, light non-aqueous phase liquid, gasoline-range organics, and diesel-range organics.

Inoculated Poplars

Our phytoremediation goals are to degrade organic pollutants in the source zone and protect trees from phytotoxicity with our endophytes. We established tree roots in impacted groundwater to mitigate off-site plume migration. Using tree roots and microbial amendments, we were able to enhance rhizosphere breakdown of source zone contaminants. This endophyte assisted phytoremediation process reduced the need for existing remediation systems that were expensive to operate.

Intrinsyx Environmental provided consulting services to design and install a twofold phytoremediation system. Phyto-1 was designed to reduce contaminant concentration in the source zone in the truck loading rack and old pumphouse. Phyto-2 was designed to provide a degradation barrier for contaminants upgradient in a plume under the adjacent road from spills at the rail loading rack. Native balsam poplar trees (700) were planted across Phyto-1 and Phyto-2 and inoculated with endophytes. Intrinsyx Environmental bored holes down to 8 feet through asphalt and vadose zone to plant the 12-foot poles. Planting trees in bore holes through the asphalt reduced costs significantly. Trees were also planted in a landfarm containing excavated contaminated soil from the rail loading rack to determine if degradation could be accelerated compared to monitored natural attenuation methods.

Utilizing balsam poplar trees inoculated with bacterial tree endophytes allows for treatment of both the contaminated groundwater and soil. Poplar trees have high transpiration rates, thereby creating a cone of depression in the water table and supporting hydrological control while degrading the contaminants via rhizodegradation, phytodegradation, and biodegradation. This process allows for effective remediation of the contaminated groundwater in the root-zone and in the tree tissue.

Found naturally in Pacific Northwest poplar trees, the endophyte microbe forms a symbiotic relationship, bolstering the tree’s resilience against harmful hydrocarbon contamination. The combined system of poplar trees and endophytes provides an effective and regenerative approach to remediation that sequesters carbon and revitalizes the soil ecosystem that is quicker and more effective than monitored natural attenuation and less expensive than traditional active remediation approaches.

The installation of native balsam poplar trees inoculated with endophytes provided source zone contaminant reduction in the truck loading rack and old pumphouse. Vadose and groundwater sampling results indicate that contaminant concentrations have declined dramatically since planting, and nearly 60 percent to 70 percent of the source zone contaminant mass has been removed. These indicators led to the expansion of the original planting area to the north, where storage tanks were formerly located, to remediate more of the site.

Regenerative Remediation

Positive results in 2023 led the client to expand the project’s footprint, and Intrinsyx Environmental has successfully absorbed and broken down a range of contaminants through this innovative, nature-based process.

This phytoremediation system isn’t just effective, it’s also regenerative. Native poplar trees with their endophytic partners create a natural barrier and filtration system, soaking up contaminants and even sequestering carbon, all while revitalizing the soil. This dynamic, living remediation system provides extensive benefits to the environment and community for the entire life cycle of a project.