The Pembina River (near Hinton) Environmentally-Sensitive Streambank Demonstrations and Training:
I met Roger Skirrow back in 2003/2004. He was a Senior Highway Engineer with Alberta Infrastructure and Transportation (AIT). Roger has been a member of IECA for some time and a CPESC. When we met in Edmonton or Calgary, during some classes I was teaching, and at that time Roger was really interested in doing some hands-on workshops utilizing Bioengineering.
After our NCHRP Report 544 ** was published in 2005, Roger became very keen and intent on putting together an “environmentally-sensitive streambank stabilization” class. He envisioned a classroom and field training on an actual stream/highway corridor. Roger wanted AIT highway engineers, consultants, biologists and regulators all together for the training.
The environmental regulations up in the Province were so strict that in most highway repair or construction projects AIT often had to “isolate” the stream from the construction zone. Isolation techniques, such as coffer dams and sheet pile enclosures, are expensive, sometimes equaling the project costs, and can also be very disturbing to the stream habitat themselves.
And here is the NCHRP Report 544 or E-Senss – Environmentally-Sensitive Streambank Stabilization Techniques manual (Report), which describes 50 biotechnical techniques, some which can be alternatives to riprap. Most importantly the Report discusses in detail the use of SELF-LAUNCHING ROCK or well graded stone. This type of rock was introduced to me by David Derrick, USACE, Vicksburg MS. But our 3-year research documents how this type of rock gradation has been utilized successfully across the country for decades. The most significant aspect of Self-Launching, AKA Self-Filtering stone is that the bank protection may NOT need a KEYED-IN ANCHOR TRENCH. If the bank protection project doesn’t need a anchor trench, then construction does not require digging in and disturbing the bottom of a LIVE STREAM. No digging in live stream, no isolation needed!!
Furthur, what if you could design a highway bank protection measure that didn’t disturb the bottom but instead, could be built by placing clean rock carefully in the live stream, enough rock and of a type/gradation that would “self launch” if scour occurred, all the while the construction would be incorporating biotechnical techniques that resulted in measurable habitat enhancement? Habitat enhancements including criteria such as cover, shade, substrate complexity, and refugia. What if this project could be built without increasing turbidity or stream sedimentation DURING construction? Also, the Report introduced/described the design and construction of 3 specific “redirective techniques” which not only direct the high velocities away from the eroding bank but also enhance the aquatic habitat. The research shows that Groins and Barbs don’t do it, but upstream-pointing Rock Vanes and Bendway Weirs have documented increases in aquatic habitat by bioassays.
Roger saw the NCHRP Report, funded by Transportation Research Board (TRB) and published by the National Cooperative Highway Research Project (NCHRP), the documentation and the case studies provided by David Derrick and others. He requested a demonstration project/training be conducted that would utilize these techniques of construction. And this is how the Pembina River/Hinton Projects came to being.
A satisfactory site on the Pembina River was located, near Robb, in the Canadian Rockies. The field site was about a 2-hour drive from Hinton where a there was training facility and accommodations for the 70+ attendees. The three-day training, which included one-day classroom and 2-days “hands-on” included over 60 engineers and consultants and about 12 regulators from Department of Fisheries and Oceans (DFO) and the Provincial Department of Environment.
One of the greatest assets this project had going for it was the participation of Ray Makowecki, Fisheries Biologist. Ray was a former Provincial Environmental regulator and very well respected. With Ray providing the extensive water quality, turbidity testing and sediment load monitoring the plan was approved for “trials”. Our monitoring plan was very stringent, a 5NTU increase for 20 minutes could shut us down for the day. If I remember correctly, the only time we got a spike in turbidity was when one of the workers slipped and his boot stirred up sediment!! The tons of clean rock used, when placed with the most-excellent machine operator, Dale, COULD be installed in a live stream with no measurable habitat degradation!!
In 2006 we built 5-7 rock vanes (I forget actual number now!) along the right descending reach of Site 1. In between each vane we built / demonstrated a different biotechnical technique. For instance, the first interval had Brushlayering, the second was Live Siltation, the third interval was Vegetated Mechanically Stabilized Earth (VMSE), the 5th Vegetated Riprap, etc. In 2007, we went back to the Pembina and stabilized another reach of stream. See how we included rootwads (LWD), Boulder Clusters (thanks Ray) and LPST w/ Live Siltation. Both seasons we utilized Compost Blankets and Compost Berms to stabilize the disturbed soils.
** The NCHRP Report 544 – Environmentally Sensitive Channel and Bank Protection Measures is available from NCHRP.
The same manual is also available from Salix Applied Earthcare and is entitled E-SenSS – Environmentally-Sensitive Streambank Stabilization Techniques. Both manuals providing the 50 streambank and biotechnical techniques are actually provided on CD. The manuals include detailed drawings (.dwg and .dgn), construction specifications, case studies, relevant research papers as .pdf, technical “white papers”, and Greenbank (technique selection software).