Soil surveys provide context and gauge risks

“Mitigations limit the degree of chemical and physical change in soil quality.”

By Ivan Whitson

Pipelines are the centerpiece of Canada’s hydrocarbon distribution system. Where Rights-of-Way (RoW) cross lands used for agriculture, the question is, “Have the soils on the RoW suffered damage that will diminish their productive capacity, especially over the long term?”

CAEPLA has provided me with a research budget to try to answer that question.

Both industry and regulators commonly claim that RoWs are reclaimed to equivalent capability. However, there have been relatively few studies on pipeline RoWs and there are no reports in the literature of using capability ratings. The monitoring programs used for pipelines are intended to find areas in need of further reclamation effort. The qualitative measures employed in these programs provide little useful data to assess land capability change. They can also generate false positives. A recently accepted publication in the Canadian Journal of Soil Science examined a sample of oil and gas well sites from southern Alberta and reported that soil quality was diminished and land capability ratings were reduced, even though these sites had received provincial certification.

Agricultural and capability ratings are used to rank soils in terms of productive capacity. I approached CAEPLA to discuss and demonstrate how land capability measurements could provide insight into reclamation effectiveness.

When viewed in isolation, small changes in pH, clay or organic matter content, and salinity or soil density may be discounted. When integrated into measures of land capability, they are a measure of cumulative effects. The research project will collect the data needed to derive these ratings and express change in terms of cumulative effect.

We know that a variety of mitigations can be used to limit soil damage on agricultural lands. Soil surveys provide context and gauge risks. Topsoils are salvaged. Upper and lower subsoil can be separated to control salinity. Where soils compact easily, traffic can be halted in wet weather.

Mitigations are intended to limit the degree of chemical and physical change in soil quality. The effectiveness of mitigations is intended to be measured by monitoring. Without monitoring, the effectiveness of mitigations remains unknown. The monitoring I will be doing is considerably stronger than that required by National Energy Board (NEB) post construction assessments.

This research will occur along the Enbridge mainline corridor using a select group of soils. About a half dozen of the 60 soil types identified for the Enbridge Line 3 Replacement project have chemical and physical properties that make them particularly sensitive to disturbance. They occupy about 20% of the 1,000 kilometre mainline corridor. These six types are “the canaries in the coal mine.”

If these soils are undamaged, less sensitive soils are also unlikely to be damaged. If they are damaged significantly, then an additional group of soils could be sampled to estimate the extent of damage.

Sampling is always meant to support conclusions about the areas that were not sampled. I plan to sample just six quarter sections chosen randomly from properties volunteered by CAEPLA landowner members. Within each quarter, four transects across the corridor will include two reference sites and three pipeline RoW sites. The RoWs will include the decommissioned Line 3, the replacement Line 3, and a third pipeline of intermediate age. Topsoil depth, organic matter content, pH, structure, density, and salinity will be measured quantitatively.

What are the benefits of this research?

The results are an independent audit of soil quality on these RoWs. Results may provide insight toward the effectiveness of construction practices and mitigations used by industry over the last six decades.

This research also audits the practices and policies of the NEB. For instance, what is the appropriate level of effort needed to quantify end-of-life liability for a pipeline RoW? This research will also provide a monitoring model that holds both industry and regulators to their promises.

Dr. Whitson is a senior soil scientist with experience in both the private and public sectors. His expertise includes soil classification and mapping, environmental assessment, hillslope hydrology, and measurement of soil change following disturbance. His graduate studies (University of Alberta) and post-doctoral work (Millar Western Forest Products) involved forest soil hydrology and nutrient transport. His work emphasizes high standards of quality, and, where possible, he has sought to publish in peer-reviewed journals. Based in Alberta, Dr. Whitson operates as I Whitson Innovations Inc., focusing on specialized aspects  of soils science.

Published in PIPELINE OBSERVER FALL 2019