Topsoil Conservation and Erosion Control
During the construction of subsurface pipelines, one of the most critical aspects in environmental conservation is the handling of the topsoil material and the prevention of erosion during the construction process. You might be asking, why is topsoil conservation important as soil seems to be abundant throughout Canada? Well, it is estimated that 1” of topsoil takes approximately 500 years to produce , which qualifies it as a non-renewable resource . As an integral resource of our functioning ecosystem, topsoil contains hundreds of years of organic nutrients that cannot be replaced once lost.
To add to the complexity of soil conservation, Canada has a wide variety of vegetation and soil compositions that can change throughout the length of a single pipeline. With varying requirements for successful conservation, the layers of soil are separated as they are excavated during construction to ensure:
- Soil mixing between subsurface sections is minimized
- Reduction of compaction of topsoil from vehicle traffic
- Vegetation is protected and conserved
- Prevention of the introduction of invasive vegetation and
- Reduction of soil erosion due to wind and water
To ensure successful topsoil reclamation, companies installing pipelines actively seek economical, practical and environmentally responsible methods of soil handling during construction. Figure 1 below illustrates some basic insights on one method of topsoil management and conservation throughout construction.
- Each section of soil type is piled and separated to prevent mixing, sometimes including separating multiple horizons of the topsoil.
- The topsoil beneath the path of travel for vehicles or equipment has been removed to prevent compaction.
- Around the trench, and in some cases, for the entire work side and a portion of the ditch side of the ROW, the first layer of the subsoil is also removed and stockpiled to ensure all subsoil excavated from the ditch is stockpiled only on similar subsoil to prevent any mixing. This also minimizes compaction issues on the traveled portion of the ROW and maximizes successful vegetation re-establishment following construction.
Figure 1: Typical Soil Management on Pipeline Right-of-Way (ROW) 
Additionally, the following best practices are typically observed to ensure successful reclamation of the completed Right of Way.
- Barriers or defined separation between conserved soil horizons are utilized to prevent water erosion or mixing.
- Barriers are typically utilized only when space is at a premium on the ROW and may consist of geotextile material in some cases. Defined separation of at least one meter between soil windrows is the preferred method of prevention.
- Mulch is not typically used as a barrier or method of separation as it is a valued commodity and usually is stored to the far outside edge of the ROW for final placement following return of all other soils. The mulch is typically where the seed bank and established vegetation is found and carefully preserving it is the best method of rapid re-establishment, particularly in forested land. In forested land, the existing seed bank in the mulch or duff layer is often all that is needed, and no seeding is required. Some projects incorporate an Environmental Management Plan actually dictating preservation and redistribution of the natural seed bank as a method of ensuring only native species re-establish following construction.
- Soil piles can be sprayed with tackifier to prevent dusting and erosion due to wind or heavy rain events.
- Sod and/or other vegetation will be carefully removed if possible and stored on the ROW for replanting typically on the far end to the outside of the topsoil pile to ensure its protection and safe storage.
With topsoil being one of Canada’s most valuable resources and the petroleum industry being a major contributor to our Country’s economic health, it is critical to maintain best practices that perpetuate long-term sustainability. SureLine is proud to participate with our valued clients in practicing sustainable, low impact construction practices that ensure the preservation of our land, water, wildlife, and mineral resources for future generations.
Pipeline.pdf – Section 4.3