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Depending on stream width, one or more samples should be taken at regular intervals across the watercourse. Surface samples are adequate in shallow watercourses (0.5 m). Depth-integrated samples or samples taken from more than one depth may be required in deeper waters.
The first downstream site or transect should be regularly monitored prior to, during and immediately following, instream activities that have the potential to generate substantial sediment. Hourly sampling is appropriate immediately below the crossing site, but frequency can be reduced depending on the length of time of instream construction and when levels return to control conditions (e.g., overnight). Sampling frequency may also be increased when instream activities are of short duration, or a specific sediment generating event is planned. It is recommended that a construction log be kept to allow suspended sediment load data to be compared to construction activities.
Additional samples will generally be required further downstream to monitor plume attenuation and determine the extent of the area affected by sediment release. Samples at these sites or transects may not warrant the same sampling intensity as the sampling sites immediately downstream of the crossing. However, supplementary samples should be added to document the start, peak and passing of sediment plumes.
Sampling should occur upstream of the crossing to provide "control" information on discharge and background levels of sediment load in the watercourse during construction. The upstream site should be located far enough upstream (typically 100 m) that it is not influenced by construction activity. Sampling frequency should be sufficient to detect natural variability in discharge and sediment load before, during and after construction.
7.1.3 Substrate Composition Analysis of substrate composition downstream of the crossing site can be used to document the deposition of sediments due to construction, monitor the physical recovery of habitats following disturbance and help calibrate sediment transport models. A variety of techniques are available, including grab sampling, freeze
Sediment traps are used to directly monitor the accumulation of small diameter sediment particles. Clean washed aggregates are used to fill a cylinder that is buried flush with the surface of the streambed. Traps are installed prior to construction activities along transects located both above and below the crossing site. They can be removed immediately after construction to assess deposition rates relative to the upstream controls, or be left in place to document sediment deposition and flushing over time.
In some watercourses, changes in channel and bottom profiles can be mapped at specified intervals along established transects. This method can be used to document changes in substrate composition following construction, identify areas of sediment accumulation and monitor recovery.
Standard visual survey or substrate description techniques can be used to compare substrate conditions prior to and after construction. The advantage of visual surveys is that they can be conducted quickly and relatively cheaply. However, they do not provide direct measures of sediment deposition and are affected by surveyor training and experience.
7.1.4 Biological Monitoring The only way to directly measure effects on aquatic communities is to monitor aquatic invertebrate, fish, algae and riparian communities to detect reductions in biodiversity, abundance, or sensitive species and life stages. Due to the wide variety of habitats and techniques available, qualified specialists should be involved to design a practical and cost-effective biological program. The following discussion outlines some factors that should be considered (see for example Tsui and McCart 1981; Weaver and Fraley 1991; Davis and Simon 1995;
Hauer and Lamberti 1996).
Aquatic invertebrates (which mainly consist of aquatic insects, mites, molluscs, crustaceans and worms) are the group of freshwater organisms most often used in aquatic biological monitoring (Resh et al. 1996). This is because aquatic invertebrates often live on the substrate, are sensitive to sediment deposition, are
Ideally, aquatic invertebrate sampling sites should be located above and below the crossing site in riffle habitats, where communities characteristic of streams and rivers are best represented, fauna diversity is highest and sensitive taxa are most likely to occur. Precise sampling locations should be selected to reflect the sediment plume mixing pattern and to ensure they have similar bottom substrate, depth, velocity, stream width, bank cover, etc. This will help to reduce natural sources of variability in the benthic samples and improve their effectiveness for assessing actual effects of pipeline construction. Benthic invertebrate monitoring data from control sites located upstream of the crossing will allow background natural variability in benthic invertebrate communities to be described.
Fish communities are sensitive, economically and socially important and respond to changes in habitat, water quality and human exploitation. Both community composition and the presence of sensitive species and life stages have been used to identify the responses of fish communities to disturbance. Since fish are relatively mobile and the effects of short-term sediment input are most likely to be sublethal, most surveys of fish communities are conducted prior to and following construction to evaluate effects on distribution, abundance, growth and species composition. Sampling may also be continued over time to evaluate subsequent recovery.
Algae that live on the bottom of waterbodies (periphyton) are at the base of the aquatic food chain and can be affected both directly and indirectly by suspended and deposited sediment. Periphyton have been used to evaluate effects on water quality because they have short life cycles, reproduce rapidly and, therefore, respond quickly to changes in water quality. Sampling design considerations are similar to those for benthic invertebrates, but fewer experienced specialists are available to analyze samples.
Monitoring of riparian habitat and biota may also be appropriate where riparian areas are identified as sensitive or unusual. A discussion of terrestrial monitoring techniques is beyond the scope of this document and qualified technical specialists should be consulted to help design a riparian monitoring program.
7.2 Post-Construction Monitoring A post-construction monitoring program should be based on specified watercourse crossing objectives and terms of authorizations, permits, licences or
compensation agreements. Post-construction monitoring may be undertaken to:
• confirm that specific crossing objectives have been achieved;
• confirm the effectiveness of protection and compensation techniques;
• observe actual effects;
• observe recovery;
• determine the need for maintenance of structures and mitigative measures; and
• fulfill explicit mitigation and compensation requirements.
Typical post-construction habitat and biological monitoring programs last for at least one year and involve periodic monitoring of habitat, aquatic invertebrates, water quality, or fish species and life stage presence and numbers. Typically, measurements of predefined habitat parameters are combined with biological sampling at transects above and below the crossing site. Methods similar to those described above for construction monitoring are used in conjunction with upstream or nearby control areas so that the influence of natural ambient factors can be identified.
Post-construction monitoring should also include periodic inspection of erosion control and habitat restoration/enhancement structures so that necessary maintenance or replacement can be undertaken (Adams and White 1990).
Alberta Environmental Protection. 1994b. Environmental Protection Guidelines for Pipelines. Conservation and Reclamation Information Letter 94-5.
Canadian Association of Petroleum Producers. 1996b. Environmental Regulatory Framework for the Upstream Petroleum Industry. Second Edition.
Canadian Environmental Assessment Agency. 1997a. Guide to the Preparation of a Comprehensive Study for Proponents and Responsible Authorities.
Environment Canada. 1975. Habitat Protection Guidelines for Construction and Forestry. Fisheries and Marine Service, Newfoundland Region. 1975.
Resources Inventory Committee. 1997. Fish Collection Methods and Standards Version 4. Prepared by Fish Inventory Unit, Ministry of Environment,
Lands and Parks for Resources Inventory Committee. Available online at:
Resources Inventory Committee. 1999. Site Card Field Guide. Available online:
http://www.trans.gov.ab.ca/Content/doctype123/production/fishhabitatma nual.htm. Last accessed January 2005.
Dwg. No. 1 Construction Technique - Typical Plow Dwg. No. 2 Construction Technique - Typical Open Cut of Small Watercourses Dwg. No. 3 Construction Technique - Typical Open Cut of Large Watercourses Dwg. No. 4 Construction Technique - Typical Dragline Dwg. No. 5 Construction Technique - Typical Flume Dwg. No. 6 Construction Technique - Typical Dam and Pump Dwg. No. 7 Construction Technique - Typical High Volume Pump Bypass Dwg. No. 8 Construction Technique - Typical Two Stage Coffer Dams Dwg. No. 9 Construction Technique - Typical Channel Diversion Dwg. No. 10 Construction Technique - Typical Bore or Punch Dwg. No. 11a&b Construction Technique - Typical Horizontal Directional Drill Dwg. No. 12 Vehicle Crossing - Typical Temporary Bridge Dwg. No. 13 Vehicle Crossing - Typical Ice Bridge Dwg. No. 14 Vehicle Crossing - Typical Ramp and Culvert Dwg. No. 15 Vehicle Crossing - Typical Ford Dwg. No. 16 Sediment Control - Typical Spoil Berms Dwg. No. 17 Sediment Control - Typical Silt Fences Dwg. No. 18 Sediment Control - Typical Straw Bales Dwg. No. 19 Subsurface Drainage Control - Typical Trench Breakers Dwg. No. 20 Subsurface Drainage Control - Typical Subdrain Dwg. No. 21 Subsurface Drainage Control - Typical Pole Drains Dwg. No. 22 Surface Erosion Control - Typical Cross Ditches and Diversion Berms Dwg. No. 23 Streambank Protection - Rip Rap Armour Dwg. No. 24 Streambank Protection - Typical Coniferous Tree Revetment Dwg. No. 25 Streambank Protection - Typical Gabion Baskets Dwg. No. 26 Streambank Protection - Typical Coir Logs Dwg. No. 27 Streambank Protection - Typical Grass Roll Dwg. No. 28 Streambank Protection - Typical Shrub Restoration Dwg. No. 29 Streambank Protection - Typical Log and Crib Walls Dwg. No. 30 Streambank Protection - Typical Hedge / Brush Layering Dwg. No. 31 Instream Cover - Typical Rock Clusters Dwg. No. 32 Instream Cover - Typical Log / Root Balls Dwg. No. 33 Instream Cover - Typical Submerged Cover Dwg. No. 34 Instream Cover - Typical Bank Overhang Dwg. No. 35 Current Deflectors - Typical Opposing Rock Wing Deflectors Dwg. No. 36 Current Deflectors - Typical Log Deflector (Small Watercourses, Width 5 m) Dwg. No. 37 Current Deflectors - Typical Groynes - Full Size Dwg. No. 38 Overpour Structures - Typical Log V Weir (Small Watercourses, Width 5 m) Dwg. No. 39 Overpour Structures - Typical Log K Dam (Small Watercourses, Width 5 m) Dwg. No. 40 Overpour Structures - Typical V Weir - Single Crest (Small Watercourses) Dwg. No. 41 Overpour Structures - Typical V Weir - Double Crest (Large Watercourses) Dwg. No. 42 Substrate Manipulation - Typical Resting Pool Dwg. No. 43 Substrate Manipulation - Typical Excavated Fish Run Page A-i October 2005 Pipeline Associated Watercourse Crossings 3rd Edition
1. Maintain a vegetation buffer at the crossing to the extent practical.
2. Install sediment and erosion control structures, as required.
3. Grade banks to allow access to watercourse by plowing equipment.
4. Complete construction of the instream pipe section.
5. Assist plow dozer with an additional pulling dozer, if warranted. Ensure adequate pulling power to plow through watercourse substrate is employed.