Site Challenge

An active petroleum hydrocarbon pipeline site had 20,000 m³ of impact and an initial plume area of 8,100 m²  based on an environmental consulting firm’s Phase II Environmental Assessment. An active recovery program over five (5) years had recovered approximately 14% of the released product but was discontinued due to declining extraction efficiencies with high operating costs.

Client’s Goal

To explore more sustainable and cost-effective remedial options for reducing LNAPL plumes, and better insight into migration risks.

LiORA Solution

LiORA reviewed the Phase II soil data collected to date to develop a customized plan for BioLodestone bioremediation and SoilSense hydrocarbon sensor placement. Once the client approved the plan, LiORA developed an optimized BioLodestone nutrient mix for the northern boreal soil. Optimized BioLodestone is up to 10X more effective than a standard biostimulant.

LiORA created site-specific designs for the SoilSense network. LiORA soil scientists configured three (3) individual sensors into one single SoilSense probe (Figure 1). Each sensor within the probe is strategically placed at specific depths that will aid in determining vertical delineation. Each sensor with bentonite is isolated from the others to ensure each measures independent concentrations as it communicates that data to LiORA’s PlumeFutures software. Each LiORA Soil probe was then placed into boreholes across the site to form a network which determined horizontal delineation.

LiORA deployed two BioLodestone Solar Powered Distributors that utilized local groundwater to flow biostimulant into the impacted area. A network of low-impact, low-footprint in-situ SoilSense sensors at 14 locations measured and tracked concentrations within the plume area. An additional SoilSense sensor was deployed outside of the plume area as a background reference of hydrocarbon levels (Figure 2). The SoilSense sensors measured: (i) fluxes of methane, carbon dioxide and oxygen as indicators of biological hydrocarbon degradation, (ii) concentrations of hydrocarbons in the soil to continuously estimate plume extent and behaviour, and (iii) physical parameters such as moisture and temperature to account for seasonal differences in biological and plume behaviour.

The SoilSense hydrocarbon sensors operated in-situ on the site and streamed measurement data from the site to LiORA’s PlumeFutures desktop software. This advanced visualization software interprets field data into depletion rates. The results can be formatted to best assist in planning, tracking, and modifying biostimulation application schedules to optimize contaminant degradation and minimize material costs.

Figure 1. Rendering of the SoilSense probes used at the pipeline site.

Figure 2. SoilSense hydrocarbon sensor network estimates of hydrocarbon depletion

Results of Bioremediation

• The network of SoilSense hydrocarbon sensors collected more than 570,000 data points from October 2021 to February 2024.
• The data stream and visualization models confirmed the LNAPL plume was stable and that the plume area was decreasing (Figure 3).
• PlumeFutures confirmed that the groundwater plume was stable and shrinking with no risk of off-site migration (Figure 3).
• Regional comparative analysis indicated that the depletion rate at this site was above average for a spill of this size (Figure 4).

The decrease in plume, stable groundwater, and accelerated depletion rate suggest that biostimulation at this site could be paused. The site was able to move into the next phase of risk management, which is monitoring natural depletion.

Figure 3. Quarterly petroleum hydrocarbon plume extents derived using the SoilSense network. Quarterly estimates of plume size vary due to seasonal influences on plume such as a rainfall and freezing temperatures.

Dashed line – Represents the initial plume size.

Gray area – Represents the 95% confidence interval of the linear fitted trend drawn in blue.

Black line – Represents the average of that quarter’s plume size.

The client used the LiORA comparison of site performance relative to other sites to prioritize spending across their portfolio. In this case, the site exceeds expectations suggesting that monitored natural depletion is likely appropriate for this site (Figure 4).

LiORA’s PlumeFutures software incorporated Phase II environmental data with sensor results to initialize a USGS 2-Layer ModFlow model of groundwater plume movement.  PlumeFutures then uses sensor data to refine the model to current conditions and project plume stability and migration over the next 50 years. The long-term stability of the groundwater plume further supported the client’s decision to move to monitored natural depletion.

Figure 4. Shows a comparison of sites across a region and identifies how this case study site exceeded expectations for plume depletion following BioLodestone bioremediation.

Blue – case study site

Circles – Individual comparison sites. Circle size represents the estimated volume of impacted soil.

Shaded gray area – represents the 95% confidence interval of the fitted gray line that links hydrocarbon depletion to the areal extent of a plume.    

Figure 5.  LiORA’s proprietary software, PlumeFutures, uses ModFlow to estimate residual groundwater plume location over the next decade.

Cost Savings

LiORA Technology led to incredible annual cost savings compared to traditional sampling and excavation methods. The SoilSense network communicated measurement data every 30 minutes instead of longer-term, higher-cost programs utilizing single-point-in-time data. In addition, because the technology is rented, it can be moved and deployed to new sites at any time.

ESG Impacts

The combination of BioLodestone active remediation with SoilSense continuous monitoring to adjust application frequency and concentration significantly improved outcomes for Environmental Social Governance (ESG):

• Soil protected: 21,000 m³
• Emissions avoided: 1,237,225 kg of CO₂-equivalents
• Safety improvements: Less heavy equipment on-site, less mob/demob to site, significant reduction in kilometres driven to remote site, and fewer personnel required to be in the field.

Conclusion

LiORA soil scientists can advise if BioLodestone is an appropriate and cost-effective active remediation method for your site. Combining LiORA’s SoilSense with BioLodestone allowed site management teams to optimize remediation systems without the costs, delays, and difficulties associated with point-in-time sampling. In active upstream sites, sampling events are often limited and difficult to organize, typically providing a very limited picture of site activity. A typical soil sample estimates hydrocarbons in 0.015L of soil, whereas a single LiORA SoilSense estimates hydrocarbons and activities in 5,500 litres of soil every 30 minutes, 365 days a year. The extensive dataset (>500,000 points) gives teams the confidence to tackle their toughest environmental challenges, knowing they’re making the most informed decision based on the latest data.  

The sensors used in this case study provide a continuous representative measurement that allows asset managers access to current data without delays to:

• Evaluate if their approach is effectively reducing hydrocarbon mass and risk.
• Determine how effective any active remediation application is working.
• Tailor application concentration and frequency to save money.
• deliver continuous data for better insight into plume stability and risk.