Canadian Consulting Engineer

Tree Of Life Award – In-Situ Bioremediation In Gladstone

October 1, 2009
By Canadian Consulting Engineer

The Neepawa-Gladstone Co-operative site in Gladstone, Manitoba had been a farm supply operation since the 1940s. Serviced by a railway, it was used to store petroleum fuels, coal, fertilizer (granular...

The Neepawa-Gladstone Co-operative site in Gladstone, Manitoba had been a farm supply operation since the 1940s. Serviced by a railway, it was used to store petroleum fuels, coal, fertilizer (granular and liquid products) and chemicals. Today, only the chemical storage operations remain.

AMEC’s environmental assessment of the site showed two distinct but comingling contaminant plumes: petroleum hydrocarbons and nitrate-nitrogen. The two plumes extended into adjacent residential properties and an undeveloped low-lying parcel of land to the southwest. Meanwhile, the site has an acute sensitivity to subsurface impacts due to moderately permeable, alluvial soils of sand, silt and clay, and shallow groundwater zones.

AMEC showed innovation in both the environmental assessment and remediation techniques. For the assessment there were no documented methods of conducting environmental field screening for nitrogen in soil, so AMEC researched existing agricultural kits and colorimetric methods for testing municipal water. Based on these techniques, AMEC developed a rapid, low cost and accurate means for field screening soil samples for nitrate impacts.

Using one contaminant to treat the other

For the remediation, AMEC worked closely with its client, Federated Cooperatives Limited, to develop the innovative concept of using one of the types of contamination (nitrate associated with fertilizer) as a consumable component in the remediation process of the secondary contaminant (petroleum hydrocarbons). By using one contaminant to treat the other, they eventually eliminated both.

The process involved the concurrent use of two research techniques, which were further developed by AMEC: Nitrate Induced Enhanced Anaerobic Bioremediation (NIEAB) and Enhanced In Situ Biodenitrification (EISBD). Previously, these technologies, particularly EISBD, had only been used at U.S. research sites. The new and successful application of NIEAB and EISBD are considered a breakthrough innovation in remediating petroleum and fertilizer contaminated sites.

The combination of EISBD and NIEAB principles using hydrocarbon based contaminants as electron donors, and fertilizer based contamination (nitrate/nitrite) as electron acceptors, was novel. What made this approach even more unique was that the only significant by-products of the process were water, nitrogen gas and carbon dioxide. This approach essentially fosters the remediation of both contaminants simultaneously.

The remediation system required groundwater collection and infiltration galleries, pump, timer and flow systems, and used the topography of the site. The system collected and redistributed groundwater impacted by the fertilizer (nitrate) to remediate the petroleum hydrocarbon con- tamination. It also treated the residual fertilizer concentrations in the groundwater, and reduced migration off site. No such system was known to previously exist.

Once the hydrocarbons had been successfully remediated, the system was later modified to use carbon-based electron donors, including common food products such as molasses, high fructose corn syrup, and emulsified canola oil, to remediate persistent concentrations of nitrate.

The remediation has reduced groundwater nitrate concentrations by 55%-98%, which is a significant environmental improvement. The groundwater petroleum hydrocarbon concentrations were reduced by 88%-98%.

Science in the field

The design and implementation of the remediation system involved a team skilled in multiple disciplines, including hydrogeology, microbiology and environmental science, and environmental, civil and mechanical engineering.

The remediation principles employed at the site were relatively simple. However, taking the theory and science from the lab to the field and having them work together successfully within a relatively tight budget proved quite complex.

Due to the large extent of the plume, including off-site impacts affecting industrial, municipal and residential properties, AMEC had to communicate with seven different stakeholders. This added complications, particularly because the remediation involves a new, relatively unproven technology.

The site would be unlikely to have been remediated using traditional “dig and dump” or “pump and treat” technologies because of the costs of such methods and the low property values.

Now, thanks to the remediation, local residents have restored confidence in using the shallow groundwater, and Manitoba Conservation, the provincial regulator, has conducted tours of the Gladstone site as a training tool and to showcase the technology.

Completed in 2008, the project was on schedule and within budget. As a result of the project’s success, AMEC is actively managing 12 other similar projects for Federated Co-operatives Limited.

Project: In-Situ Bioremedial Technologies at a Petroleum and Fertilizer Distribution Facility, Gladstone, Manitoba

Award-winning firm prime consultant: AMEC Earth & Environmental, Winnipeg (Patrick Campbell, B. Sc., Harley Pankratz, P. Eng.)

Client: Federated Cooperatives Limited


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