Clay Pad Removal & Site Revegetation A Peatland Restoration Trail

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Margery Potter
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1 Clay Pad Removal & Site Revegetation A Peatland Restoration Trail

2 Outline Site Adjustment: Wellpad Inversion Jean-Marie Sobze Site Re-vegetation Marie-Eve Gauthier

3 Background Reclaiming peatlands to upland ecosystems will fall short of restoring the hydrological and peataccumulating functions of peatlands. nbri developed in collaboration with the Laval University and Shell Canada a project to restore full scale wellsite constructed on peatland

saturated - but not inundated peat surface Establish

4 Objectives Restore surface hydrologic connectivity with the surrounding peatland Create a stable saturated - but not inundated peat surface Establish plant community similar to the surrounding natural peatland.

5 Research Area The research site is located within a poor fen in the Peace River Region The site is 1.4 hectares The site was drilled but not operated The peat depth in natural undisturbed surrounding peatland was 1.1m The depth of the compressed peat under the wellpad varied from 40 to 80 centimeters The north side of the pad was 30 cm lower that the south side

6 Research Area The site adjustment took place in the winter capitalizing on frozen winter road access to haul the dirt. Clay pad overburden was returned to a nearby borrow pit.

7 Site Adjustment Methods Three main methods were applied to adjust the site: Complete pad removal and peat fluffing Complete pad removal and peat inversion Partial pad removal and peat inversion

Pad Removal and Peat Fluffing Fluffing is the

8 Pad Removal and Peat Fluffing Fluffing is the activity of using an excavator to work-up the surface of peat and to add volume. This method consist of: Complete removal of the clay pad and geotextile Decompaction/fluffing the peat layer that was compressed under the clay pad.

9 Inversion Strip Methods The inversion methods involve inserting a layer of pad material under the peat. This process resulted in a layer of surface peat above the well pad material. Six-step Inversion Two-step Inversion

10 Six-step Peat Inversion The six-step peat inversion consisted of : 1. Complete removal of the clay pad and geo-textile 2. Removal of the peat from the one strip and pile all along the other strip. 3. Establishment of temporary markers to monitor the clay and peat depth

Return the peat piled on the first strip to the top of the second

11 Six-step Peat Inversion 4. Half-fill the second strip with clay from the third strip 5. Return the peat piled on the first strip to the top of the second strip 6. Lightly compress the peat surface for the first and second strip and use the markers to monitor the elevation

12 Two-step Peat Inversion This method consisted of the following steps: Removing a portion of the pad material along the strip Creating a 5 m by 5m opening on the first section of the strip by removing all clay and peat. Removing the remaining clay and geo-textile from the second section and fill the bottom of the first section. Removing the peat from the second section to cover the clay on the first section. Use reference markers established at the edge of the strip to assess the surface elevation

13 Two-step Peat Inversion Difference with the Six-step: Geo-textile remains on site although it is buried under the peat layer. Resulting peat surface contains a bit of mineral soil. Advantage: The inversion is shorter compare to the six-step.

in the summer was East west How do you accurately

14 Site Adjustment Outcome We predicted predicted a North South water flow (Strips orientation) Water flow observed in the summer was East west How do you accurately determine water flow direction at a wellsite level? (Wet Area Mapping?)

15 Goals of Restoration Two components in our restoration plan: Hydrology (pad removal) Vegetation Short term goal: Reestablish peatland plant cover, particularly moss cover Restore tree cover Long term goal: Restore peat-accumulating function

16 Re-vegetation Restoring the moss and plant cover: Active re-vegetation strategy based on reintroduction of seed bank from donor natural peatlands Moss transfer technique ( Rochefort et al ) Restoring tree cover: Tree planting scheduled for 2013

17 Site Description ][

18 Re-vegetation Treatments ][

19 Donor Sites 3 1 Inversion Pad 2

20 Harvesting Moss Layer of ][

21 Impact on Donor Site 3 Inversion Pad ][

22 Impact on Donor Site August June May 2012 ][

23 Collecting Harvested Material of ][

24 Transport ][

25 Spreading Moss of

26 Spreading Moss of ][

27 Spreading Moss ][

28 Spreading Moss of ][

29 Protective Straw Mulch of ][

suitable re-vegetation techniques Monitoring plant communities

30 Monitoring Cost-effective and ecologically suitable pad removal techniques Monitoring hydrology Cost-effective and ecologically suitable re-vegetation techniques Monitoring plant communities Recommendations based on knowledge Design of subsequent par removal trials

31 Discussion Working in summer Operational constraints Problems encountered Site conditions of Time line Monitoring schedule Next trials Replicates and cost-effective

32 Thanks Shell Canada National Sciences and Engineering Research Council of Canada-NSREC Alberta Environment Sustainable Resource Development DMI Northsite Contractor Laval University University of Calgary FPI Innovation of

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