As opposed to building a low environmental impact and aesthetically pleasing multi-span/clear span bridge like the Stoney Trail bridge over Bow River, Alberta Transportation and the construction company KGL Constructors are building a high environmental impact and ugly cut & fill bridge. This bridge design, also called an earthen berm, will disconnect a large portion of this 1 km wide river valley from its broader (1) hydrologic and hydraulic processes, (2) geomorphic processes, and (3), biologic processes, collectively known as watershed management functions. The structure will create a barrier that fragments the wildlife and biodiversity. 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".
Here is an example of the type of bridge currently being built. This style of bridge operates as a dam and forces the river through a small narrow opening.
To put this into perspective, each of the bridges on the TransCanada Highway between Calgary and Canmore are 5.2 m high. These bridges sit on earthen berm abutments. Now double the height of the earth section to 10 m and this is what one will see at the river crossing. Now increase the height by 3.5 times (18 m) and this is the height of the berm on the north side of the Elbow River Valley. The base of this 850 m long earthen berm (dam) is approximately 250 m wide, which is required to support a 150 m wide road right of way. This equates to approximately 2.3 million cubic metres of dirt being placed in "Calgary's most biodiverse river valley". Is this the best we can do with bridge technology in 2017?
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.
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.
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
In our opinion, this design will have a significant and adverse impact on the ecosystem and biodiversity that inhabit this beautiful valley. With a choked back, design one is altering both the natural hydrological and ecological processes that are currently in place. This alteration of natural processes will deprive this portion of the Weaselhead from receiving valuable sediment and nutrients that are vital for sustainability. Filling in the valley and associated wetlands will also have an adverse impact on the Beaver Pond in the southwest corner of the protected Weaselhead Natural Park, i.e. the west end of the pond will be filled in and the wetland to the south that is hydrologically connected (supplying oxygenated water) will also be filled in.
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. For additional information, please visit the Solution page.
The aerial photograph below was taken on June 3, 2017. Look at the devastation that has been done to this once pristine valley. How does this devastation comply with the spirit and intent of the Durban Commitment on Biodioversity that the City of Calgary signed in late 2016?
While many around the world have referred to oil sands plants as being "ecocide", this highly destructive, large footprint project sure looks like ecocide right on our back door.
Shame on the Alberta Government.
Photograph courtesy of the Weaselhead/Glenmore Park Preservation Society and John Mader.
For additional aerial photographs, please visit the WGPPS recent pictures site.
Download a copy of Mike Ellis' (MLA Calgary West) Ring Road Update, where Mike Ellis states, "I have pointed out to Minister Mason the flawed bridge design and its flooding potential during the Tuesday, June 6 meeting. The Minister has indicated he will widen the watercourse of the bridge. He also indicated it was a good idea and instructed Ring Road staff to look into incorporating water culverts in the earth fill portion to allow for additional water flow". Why has Minister Brian Mason since reneged on his promise to widen the bridge and incorporate culverts into the design?
For more on SWCRR concerns watch this YouTube video
Rescue Our Wetlands (Courtesy of Ducks Unlimited)
Wetlands the Drain Game (Courtesy of Ducks Unlimited)