Build a Better Bridge
Across the Elbow River Valley, Calgary’s most biodiverse river valley,
like this clear span bridge across the Bow River
Build a Better Bridge
Across the Elbow River Valley, Calgary’s most biodiverse river valley,
like this clear span bridge across the Bow River
As opposed to building the clear span bridge that was recommended to the Government by Alberta WaterSmart, Alberta Transportation are building a long and wide elevated earthen berm causeway across most of the 1 km wide valley. As can be seen, this man made road embankment required several hundred thousand truck loads of dirt. What was once Calgary’s most biodiverse river valley can now be best described as “ecocide“.
Unlike with an environmentally friendly clear span bridge where the river is free to move back and forth as it does naturally, this causeway required a significant realignment of the Elbow River. Applications have been submitted to the Department of Fisheries and Oceans (DFO), but to date no permit has been approved. Moreover, work in this valley has occurred without any regard to the fish habitat and riparian buffer.
Wildlife are now expected to traverse in excess of 250 m through 25 m wide corridors on either side of the relatively narrow 157 m wide bridge. The experience to date in Banff National Park has shown that corridors of this length either don’t work or they become predator killing zones. Further studies have shown that barriers like this causeway will fragment a valley, which in turn results in a substantial loss of biodiversity.
While Alberta Transportation has admitted that the proper clear span bridge could be built for $100 million as opposed to $50 million for the causeway, they continue with a flawed design that had 30 bridge failures during the 2013 flood and 90 more bridge repairs. Moreover, even Alberta Transportation’s own engineers stated at a June 28, 2017 Information Session that this design “does not comply with floodplain management best practices”.
Naturally functioning riparian areas are a product of a tightly interconnected system of the water shed management functions and its associated processes. Ecosystems sustain themselves by means of these ongoing processes. The Association of State Floodplain Managers state, “Human activity, especially urbanization and altering of the flooding process as a means of controlling and/or storing water, interrupts these natural processes and thus disturbs the overall impact of the ecosystem”.
Rivers are the lifeline of the landscape, transporting water, sediment, organic material, and nutrients from mountains to oceans. Floodplains are key components of the active river area that serve as storage reservoirs for these key elements of life. Without floodplains there would not be storage of nutrients to grow food, flood reduction, and sediment storage.
The Association of State Floodplain Managers further state, “In our attempts to transport runoff and flood waters efficiently through the watershed, we have used structural interventions (such as concrete lining, revetments, floodwalls, jetties, diversions, and dams and reservoirs) that interrupt or modify natural hydrologic, hydraulic, geomorphic, and biologic processes. The ground surface and natural vegetation are disturbed during construction. The structures change the natural movement of water in one or more ways such as altering the speed, restricting movement across the floodplain, and changing sediment loads. Floodwalls and levees increase flow discharge and elevation when they constrict high flows into a narrow path. Land use policies that allow encroachment into the floodplain can cause dramatic channel migration downstream. Changing the frequency of floodplain inundation can encourage invasive species to supplant the native vegetation. Most riparian and coastal animal species are specifically adapted to the flow patterns and other characteristics of their native habitat. This makes them vulnerable to disruptions in the flow and water levels”.
Living along rivers and using the resources that rivers provide has led to widespread channelization where a river is fixed in place and is not allowed to flood into its floodplain. Berms, levees, flood walls, rock riprap, and dams are some of the many ways that humans have tried to control rivers. The irony is that this mismanagement has tended to increase risks of flooding and erosion while reducing valuable ecosystem services such as nutrient retention and soil building.
Some of the problems with this non environmentally and non watershed management earthen berm bridge design include:
- The design alters the natural hydrological and ecological processes that are currently in place
- Increases risk of upstream flooding, especially Discovery Ridge and the Tsuu T’ina Nation lands
- Breach of stormwater storage could contaminate our drinking water
- Forces the river through a relatively narrow opening, increases water velocity which causes harm to the Weaselhead and Biodiversity
- Blocks the free movement of wildlife in the valley and increases the potential for vehicle/wildlife collisions
- Channel realignments at the Elbow River crossing will result in a permanent decrease in existing fish habitat
- Failure of the “Dam” could cause significant damage to the Weaselhead Flats and downstream communities
Room for the river is based on a strategy of ‘working with nature’ – A new era of river management is underway; people understand that rivers and floodplains are formed by dynamic natural processes that must be maintained to reduce risks and retain ecosystem services. In other words, give the river some room to move and it will tend to be less destructive and more beneficial. The Association of State Floodplain Managers emphasize the following: “it is imperative that we eliminate the attitude that it is acceptable to obtain short-term reductions in flood risk and/or short-term economic gains by shifting those costs to future generations or causing adverse environmental impacts”.
Unfortunately this earthen berm bridge design does not comply with the new era of river management best practices. This design also contradicts the spirit and intent of the Flood Recovery & Reconstruction Act (no more fill in the floodways) and in our opinion, violates the intent of Alberta Environment & Parks strategic and guiding principle documents, “Water for Life” and “Stepping back from the Water”.
The Scottish Environmental Protection Agency (SEPA) in their 2010 report entitled, “Engineering in the water environment: good practice guide – river crossings” notes the consequences of poorly designed structures in a floodplain. Their findings include:
- Poorly designed structures can increase flood risk upstream due to a lack of capacity beneath the structure. Other structures may have sufficient capacity to take even the highest flows but, if they block the floodplain (e.g. by road embankments), an increase in upstream flooding can still occur.
- Disconnecting the floodplain from the river can also lead to the loss of floodplain habitats. Crossings can constrict flood flows, forcing flood flows through a relatively narrow opening at a crossing point. This can increase bed and bank erosion, and alter sediment deposition damaging river habitats and crossing structures.
Hydraulic modelling has shown that even a two-year return period flood will cause the earthen berm to act as a “dam” and cause ponding upstream. This large earth “dam” also prevents the floodplain and wetlands from doing their natural job; including storing and conveying floodwaters, improving water quality, and facilitating groundwater recharge. Interruption of these natural processes will also negate the ability of the floodplain to absorb water and recharge the aquifer. One acre of floodplain can store up to 1.5 million gallons of flood water and this projects footprint consumes 150 – 175 acres, which equates to 0.85 – 1.0 million cubic metres of lost water storage).
As David Suzuki’s June 29, 2017 article (“Nature offers the best defence against flooding“) on floodplain management points out, in times of flooding, this design prevents the floodplain from doing its natural job and more water will now flow downstream into the Glenmore Reservoir, which is counter to all of the flood mitigation programs. Plus as the upstream aggradation and silting continues, this design increases the risk of flooding in upstream communities.
Visit this link for additional information on the bridge hydraulics
The City of Calgary in their January 5th 2015 report to the Deputy Minister of Transportation note concerns with the designs adverse impact on drinking water quality. In this report they state:
“There are several means by which the ring road may cause water quality issues for the City:
o Channel realignment and channel constriction may result in increased localized velocities. This will cause accelerated channel erosion that leads to increased sediment mobilization.
o Vehicle collisions, hazardous material spills and use of salt and use of gravel on the ring road may introduce harmful chemicals into the Elbow River.
o Potential for pollutant risk to native habitat through sedimentation, chemical or noise pollution associated with the freeway and associated stormwater systems immediately upstream.
o Hydrocarbons and heavy metals from road runoff will be introduced into the Elbow River”.
The friends of the Rouge River online report entitled, “Correcting Stormwater Mistakes”, also states, “Many new urban developments use large ponds to reduce flash flooding. However, if these ponds are built in a stream valley or flood plain, they destroy sensitive soils and habitat. Furthermore, if ponds are created with berms within a flood plain, they can aggravate flood damage during a major storm by clogging the flood plain with silt and debris. Stormwater ponds should not be located within stream flood plains, valleys and environmentally sensitive areas”
In order to stop the development-centred approach to floodplain management, where encroachment into the floodplain results in floodwaters rising higher and spreading out further (causing more and more damage), the Alberta Government passed Bill 27, the “Flood Recovery and Reconstruction Act”. This law was supposed to result in Regulations that prevent further infilling of Alberta’s floodplains and reserve this area for the floodway to do its natural job. It’s been 3.5 years since this Law was passed and we still do not have the Regulations. Regardless of the Regulations, even non-law makers can understand the intent of this law. So we call on the Alberta Government to stop filling in Calgary’s most biodiverse river valley.
Is there a better way? Yes. The below style of bridge (Stoney Tail bridge over the Bow River) is more effective in minimizing the negative effects of the river crossing. See below
The River Always Wins
In a floodplain with a wide meander belt and a highly laterally moving river, the preferred approach to bridge design is to span the entire width of the geomorphically active floodplain or, as it is often referred, the active channel migration zone. In this valley, the meander belt width is 650 m yet the bridge opening is a fraction of this size. The following reports emphasize the best practice:
- In a January 5, 2015 report from the City of Calgary to the Deputy Minister of Transportation, the City advises, “Bridge crossing spans shall be sufficiently wide to accommodate a reasonable amount of river morphological change (i.e. 1.5 to 4 times the Elbow River meander belt width) to accommodate some channel migration within the bridge span”. This means that the bridge should span the valley;
- The City of Calgary Transportation Plan (2009), “A clear span bridge is usually the preferred type of crossing because it typically causes less impact to watercourse and flood plain functions”;
- The Klohn Crippen Berger report (Nov 2015) further reinforces this notion and they state, “ Further designs should accept and expect river mobility as much as possible. The design philosophy should be to protect the infrastructure (i.e. road embankment, bridge piers and abutments, and stormwater ponds) to an appropriate level, rather than to attempt to control the river”;
- Alberta WaterSMART in their “Room for the River Pilot in the Bow River Basin, Advice to the Government of Alberta” report (Dec 19, 2014) state, “Revise the SWCRR plans to include a wide span bridge, preserving room for the Elbow River” and “Consider alternatives to optimize room for the river considerations at this location”; and
- The Deltares report (Oct 2015) regarding the Springbank and McClean Creek Dry Dams also states, “The province should continue to pursue the multiple layers approach flood mitigation as outlined in previous work on Room for the River, structural mitigation is only one element. Programs like wetland restoration, floodway regulations and removal of obstructions should continue.”
The designers of this bridge have ignored this advice from the “experts”.
Environmental and watershed management groups have also weighed in on this issue. Their comments include:
- The Canadian Parks and Wilderness Society in a March 17, 2015 to the Minister of Transportation state, “CPAWS SAB believes that leaving the natural river course at the three crossings and constructing open-span bridges across Fish Creek and the Elbow River valleys are the most appropriate measures for the Calgary Ring Road”;
- The Alberta Wilderness Association in a report entitled, “A closer look at Bow Basin flood mitigation proposals” (2015) states, “The overwhelming funding preference for building flood mitigation infrastructure gives the impression that watershed ecology is only of symbolic importance to the Alberta government. Ideally, more attention should be placed on developing and maintaining river sinks that will not disrupt natural habitats. They are very good long-term flood mitigation solutions. This is the message AWA continues to deliver to our elected officials”; and
- In a statement on its website about ring road concerns, the Weaselhead/Glenmore Park Preservation Society (WGPPS) notes that limiting the meandering of the Elbow into a new channel could “alter the ecosystems, biodiversity, water quality, fish habitat and more, while reducing forest rejuvenation and increasing risk of forest fires over the long-term.” It also cites concerns about negative effects on water quality and on parks, the local community, and wildlife. “I don’t think they [Alberta Transportation] understand how unique the Elbow River is,” WGPPS’s Dahlseide said. She added that designers may be underestimating the power of the river, especially in times of flood. “I don’t think that’s wise.”
This advice from environmental groups that have watershed expertise has been ignored.
Figure 1 on the right, demonstrates what happens when a river meander (bend) is cut off by a new channel. This abandoned channel creates what is know as an oxbow lake. As can be seen in figure 2, the channel realignment as proposed by Alberta Transportation will eventually create an abandoned channel (an oxbow lake), when high-velocity flood waters take a short cut.
Given that this meandering river concept is widely understood by geoscientists and river morphology specialists, we are not sure why Alberta Transportation is investing tax dollars in a realignment that will fail. If they are to realign the channel, then the best practice would be to dredge the inevitable “short cut” and widen and deepen this new channel, which will slow down the water velocity.
Appendix B of the Calgary Transportation Plan, “Principles and design considerations for river crossings” also states:
- All transportation crossings of rivers and creeks require the construction of culverts, piers and bridges, and have the potential to affect riparian areas and river and creek habitats. For these reasons, the need for river and creek crossings must be balanced with impacts to the environment and be treated with the utmost environmental sensitivity.
- It is essential to balance the need for expanded infrastructure with the significance of the environmental areas and communities that may have to be crossed. When a crossing is deemed necessary, these facilities should be designed and constructed to protect the rivers, creeks and other natural ecosystems that will be affected.
- A balanced triple bottom line framework should be used to assess the social, economic and environmental implications of the crossing and the corridor it serves and all alternatives, including the option of doing nothing.
This notion that the proposed channel realignment is being engineered for failure is reinforced in the Transportation Association of Canada’s Guide to Bridge Hydraulics (2004). Figure 5.18 in this report, a figure from 1903, recognized that the river will take the “expected short cut”.
The Transportation Association of Canada’s Guide to Bridge Hydraulics (2004) also states, “Channel realignments or diversions were widely used in the past to simply bridge crossing layout and to reduce the potential for channel shifting and erosion. Concern over environmental impacts has resulted in realignments and diversions receiving critical scrutiny from environmental authorities and the public”.
Paul Finkelman, President of the Weaselhead/Glenmore Park Preservation Society stated at an October 7, 2014 open house at the Cedarbrae Community Centre, “A lot of people don’t know but they are re-routing the Elbow River by a kilometre to accommodate a small bridge, which we think is ridiculous. It won’t even withstand a flood like the one in 2013”
The Alberta Government report “Stepping Back from the Water a beneficial management practices guide for new development near water bodies in Alberta’s settled region” (2012) sums it up:
WATER ALWAYS WINS
The illustrations below from the 2013 flood demonstrate the destructive nature of flood waters. Bridges that were designed in accordance with Alberta Transportation standards failed due to scouring at the bridge foundations and road embankment. This concern with bridge site scouring and erosion is also raised by the Transportation Association of Canada in their 2004 Guide to Bridge Hydraulics report. Sites susceptible to scour include:
- Bridges in erodible streambeds – especially sand or fine gravel – with scour-vulnerable design features
- Sites on frequently shifting stream channels, or where flood currents strike piers and abutments at severe angles of attack
An Alberta Transportation presentation, “Geotechnical Considerations from the June 2013 Southern Alberta Flood” provides an overview of the power of the 2013 rainfall event:
- 174 landslides, debris flow and debris flood events were documented.
- This was in addition to 157 road washout locations, 135 major erosion sites and more than 200 blocked culverts.
- 30 bridges were severely damaged and had to be closed for repairs while 90 other bridges required minor repairs that did not require closure.
Given this very high bridge failure rate, we concur with the Weaselhead/Glenmore Park Preservation Society’s assessment, i.e. we don’t think they [Alberta Transportation] understand how unique the Elbow River is and we believe that designers may be underestimating the power of the river, especially in times of flood.
A Signature Bridge – Truth & Reconciliation
That is a tribute to the Nation – Its never too late
Let the Nation Finalize the Design
Build a clear span bridge across the Elbow River valley.
This low environmental impact bridge, complies with floodplain management best practices, i.e. it facilitates proper flood flow conveyance, it allows the river valley to act as sponge and absorb and store water, it does not put upstream homes at risk, in times of flooding it will recharge the nutrient supply in the Weaselhead Natural Park, it does not fragment the valley, and it does not harm the biodiversity that inhabit this valley. Moreover, this design complies with the recommendations made to the Alberta Government by experts in the field of floodplain and watershed management.
- The City of Calgary Transportation Plan on page B-2 states, “A clear span bridge is usually the preferred type of crossing because it typically causes less impact to watercourse and floodplain functions”.
- Klohn Crippen Berger have stated that the design philosophy should be to protect the infrastructure (i.e. road embankment, bridge piers and abutments, and stormwater ponds) to an appropriate level, rather than to attempt to control the river.
- Environment and Climate Canada state: “Governments have attempted to alleviate flood situations in Canada by building protective dykes and creating upstream storage, and through emergency aid and disaster assistance. Although many of these measures are beneficial, they also serve to encourage further encroachment upon river floodplains, thereby raising the potential for flood damage and leading to requests for greater levels of protection. In other words, the structural solution is only a partial one; the only long-term solution consists of keeping flood-vulnerable development and uses out of the floodplain. This non-structural approach has gained wide acceptance, since it reduces the need for expensive flood control structures and the demand for disaster assistance payments caused by flood damage. The approach includes:
- regulating land use in the floodplain;
- floodproofing measures;
- acquiring property in the floodplain or relocating structures;
- altering upstream land management practices; and
- establishing and maintaining flood forecasting and warning systems”.
- The Washington State, Water Crossing Guidelines states, “The preferred approach is to span the entire width of the geomorphically active floodplain or, as it is often referred, the active channel migration zone”.
- Alberta Transportation at the 2015 Transportation Association of Canada conference states, “Current design standards and practices may not reflect the demands imposed by repeated extreme weather conditions. A shift from continually repairing highway infrastructure to building more robust, and capital intensive, engineering designs may be required. Design philosophies that are based on historic 1:100 design events or similar antecedent events will have to be recalibrated to match the new norm and recalibration will have to be done frequently to keep pace with the increasing frequency of extreme events”.
- Modern bridge building is much more than concrete, steel and money. The overall socioeconomic impact, influence on people migration, traffic, use of primary materials, safety of construction impact on the environment, energy, risk scenarios, health, and climate and CO2 emissions, are among the parameters which enter into the decision process at the overall holistic conceptual level, the more detailed level of selection of bridge sites, and selection of bridge types as well as construction methods and selection of materials and products.
- Alberta Transportation should incorporate the “best practices” from the Scottish Environmental Protection Agency (SEPA), , the Association of State Wetland Managers (ASWM), Hauer et al (June 2016),Ostenfield (2011), and other innovative ecofriendly integrated solutions into the options analysis. Without considering a range of options it is not possible to determine if the chosen approach represents the most suitable option
- The Scottish Environmental Protection Agency River Crossings, Good Practice Guide states, “The most cost-effective solution is the one that minimizes environmental harm or maximizes environmental benefit at a proportionate cost”.
- Alberta Transportation should use an integrated framework with options analysis for selection of the bridge design. This approach should incorporate the best practices from the City of Calgary’s Triple Bottom Line, however, this economic, environmental and social evaluation model should also include engineering as an attribute. The integrated multi-disciplinary approach to design can result in a sustainable bridge that can stand the test of time; a bridge that becomes a point of pride for the citizens of Calgary and a design that draws people to the river valley. Further, for bridges spanning a sensitive ecosystem, then the environmental attribute should have a higher weighting in the evaluation process.
- Bridges should harmonize with their surroundings. Developing a bridge to blend with its surrounding area is a concept that all designers should consider at the beginning of their project. We believe that this is even more important when a bridge crosses a sensitive environmental area.
- The design approach should build off of the approach used by the City of Edmonton to build the Walterdale Bridge Replacement bridge, i.e. it needs to stand the test of time; it should be a point of pride for the citizens of Calgary and a design that draws people to the river valley.
- The design and construction process should minimize any adverse impacts on the ecosystem, the biodiversity that inhabits this system, the floodplain, and water supply both for today and tomorrow.
- Appendix B of the City of Calgary Transportation Plan states, “All transportation crossings of rivers and creeks require the construction of culverts, piers and bridges, and have the potential to affect riparian areas and river and creek habitats. For these reasons, the need for river and creek crossings must be balanced with impacts to the environment and be treated with the utmost environmental sensitivity”.
- The design should be forward looking and endeavor to incorporate a platform for rapid transit (LRT) and multi-user pathways.
- Alberta Transportation should be investing as much in the Elbow River Bridge, as they have in the Bow River Bridge and/or other bridges and interchanges in this Province, as right now the design appears to be totally driven by the least expensive upfront cost, as opposed to incorporating the environment, social costs, and damages.
- At the June 28, 2017 Information Session at the United Church in Lakeview, members of the Alberta Transportation engineering team were asked a simple question, “does the Elbow River bridge crossing comply with floodplain management best practices?”. The answer was NO. Consequently, we urge these engineers and the policy makers to visit the Reports section of this website and review the documents listed under “floodplain management best practices“.
Here are some renderings of the SWCRR Bridge when the intent was to use 37th Street SW. While we are not requesting a suspension bridge, the intent was to build a clear span bridge and not a road embankment/dam.
There is still time to get this right. Further, working in consultation with all stakeholders will ensure that this project is not only built right, the right way, the first time, and with respect for the respect for the environment and the biodiversity, but that it comes in on schedule and on budget.
CALLING ON THE ALBERTA GOVERNMENT TO WORK WITH THE COMMUNITIES AND STOP WHAT IS AKIN TO ECOCIDE IN THE ELBOW RIVER VALLEY.
BUILD A BETTER BRIDGE
Embrace Technology and Best Practices
New Bridge Technologies (Low Environmental Impact):
These processes that embrace modern technology are not only “low environmental impact”, they save time and in the long run may be less expensive.
a) The SLJ900/32, or the Segmental Bridge Launching Machine
b) Alconetar Bridge – Construction Process
c) Incremental Launching Process
d) Full Span Launching
Click below to view the reports on the Elbow River Bridge