OSE visual reference guide. Coarse Woody Material (CWM)

Transcription

1 OSE visual reference guide Coarse Woody Material (CWM)

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3 This guide will address two main issues regarding OSE reclamation practices which have been evolving over a short period of time. 1. The management of woody materials. Over the past 10 years or so the management of woody materials has shifted from piling and burning, to mulching, to the current practice of the placement of coarse woody materials (CWM). Effective placement of CWM encourages the development of microsites (areas where trees and vegetation can establish and thrive). 2. Mounding of well centers and cut & fills. Settling well centers and cut & fills have resulted in expensive follow up reclamation work. There have been ongoing learnings on the practices of mounding well centers (i.e. height of mounds) and cut & fills to allow for eventual settling of materials to match the existing contours of offsite conditions. Current practice and acceptance by regulators has shifted to allow for slight mounding vs settled well centers and sharp lease edges.

4 How much Coarse Woody Materials (CWM)? Rough guide: You should be able to hit dirt with a shovel in at least 3-4 spots within arm s reach. If you cannot, it s probably too much CWM. The amount and placement of CWM does matter. The CWM should be randomly spread along the access roads and wellsites and eventually the site should blend into the adjacent forested areas Once a proper rollback is carried out, the site should appear messy or rough looking We are NOT looking for a flat smooth surface. Trees and woody plants thrive in the micro sites created from an uneven surface and random CWM placement. Limbs, tops and non-merchantable timber should be left on location where possible

5 Considerations for appropriate Coarse Woody Material (CWM) coverage Approx. 50% of the site is covered with CWM Random & not too thick, allows trees to take advantage of micro sites for growth No piles, CWM should be touching the ground

6 Excessive CWM Improper placement or rollback practices require sites to be reentered to reduce the amount of CWM, increasing reclamation costs, and pushing back the OSE reclamation process There must be sufficient exposed soil for plants to become established Existing piles of CWM should be spread out randomly across the entire site and access Excessive piles of CWM can be a fire hazard

7 Considerations with excessive CWM Will not match offsite conditions and could result in additional reclamation work Large piles can turn into a fire hazard Do not compact the CWM, avoid repeatedly running over the material with large equipment

8 Insufficient CWM Without enough CWM present on site there is a tendency for undesirable grasses to establish instead of woody desirable plants and trees A lack of microsites and CWM will result in a delay in vegetation growth and reduction of woody plants Erosion channels may form resulting in follow up reclamation work

9 Considerations with insufficient CWM Without sufficient CWM the OSE sites are more prone to erosion Grasses tend to get established vs desired woody plants CWM spread across a site tends to discourage travel by 3rd parties across sites

10 Fine woody materials & mulching A hoe is preferred for spreading CWM as it does not break down the larger pieces and can leave the surface mounded Avoid the use of cats where possible, they tend to leave a site compacted and flat Once done with a roll back the site should be rough and loose

11 Impacts of fine woody material & mulching Avoid the use of fine woody material and breaking down or compaction of large pieces of wood Mulch blocks sunlight and leaves no microsites for vegetation to grow Fine woody material on a site can result in vegetation growth that is clearly stunted or even nonexistent Fine woody material & mulching

12 Mounding well centers Well centers should be mounded: m for low lying wet areas m for higher upland areas Ice and/or snow incorporated into the mound will increase settling (mound height should take this into consideration) Mounding in low lying areas Low lying wet areas will have greater settling than high upland areas, and may experience settling over more than one season It is okay if a mound is still present after a few years of settling, over time these mounds can act as a micro site for vegetation establishment The mound may look too high, but it s probably not! Mounding in high upland areas Generally speaking high upland areas will have less settling than low lying areas and can be mounded to a lesser extent, but mounding is still required

13 Examples of appropriate well centre mounding for low lying areas Previously wooded spruce bog site mounded in winter between 1.6m - 1.8m in height Settled over 1m by end of following summer Ice and/or snow incorporated into the mound will increase settling (mound height should take this into account) Mounding high & low lying areas

14 Examples of appropriate mounding for high upland areas Previously wooded upland sites mounded in winter approx. 0.6m in height Settled over 0.5m by end of following summer

15 Examples of appropriate well centre mounding for low lying areas Previously wooded larch bog site mounded in winter approx. 1.6m in height Settled over 1m by end of following summer

16 Results of insufficient mounding on OSE sites Large sunken well center filled with water does not blend into surrounding area, and can be a safety hazard Reclamation is expensive as the access is usually remote, requires heavy equipment, and disturbing vegetation

17 Examples of appropriate mounding for high upland areas Previously wooded upland site mounded in winter approx. 0.6m in height Settled over 0.5m by end of following summer

18 Cut & fills (matching off-site contours) 0.7m 1.0m of fill should be placed on the cut area along the edges of the lease boundary 1.0m - 1.2m if there is a large amount of snow or ice mixed in with the fill material (with the melting the material will settle further) Sites are to be left rough and loose with CWM spread randomly across the site (not smooth and compacted!) The area of the OSE site that was cut should be re-contoured to tie into or match the existing offsite topography/contour Proper contouring and matching of offsite conditions will reduce erosion and channeling

19 Examples of successful cut & fill rollbacks Site was overbuilt/ mounded along edge of cut by 0.8m 1.0m with CWM, soils are spread rough and loose Settled >1.0m by end of following summer with vegetation moving in from offsite Cut & fill rollbacks

20 Results of cut & fills on OSE sites Sites were not properly contoured and filled in to match offsite elevations Both sites required winter access reclamation work to re-contour and mound sites to allow for settlement Sites were then planted the following summer to assist with vegetation growth

21 Examples of successful cut & fill rollbacks Site was overbuilt/mounded along edge of cut by 1.2m with CWM, soils are spread rough and loose Settled over 1m by end of following summer to match offsite levels

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24 September 2016 Cenovus Energy Inc. 2016