What we Can learn from the Yorkton Backwash
Water Reuse Project and Flood Proofing Plan
Executive Summary
This report examines the different approaches that the City of Yorkton used to address two water problems. The first one is the backwash water treatment problem which emerged when the City started the construction of its new water treatment plant. The Department of Environmental Services came up with an innovative approach to treat the backwash water onsite. However, due to the novelty of the approach and the sensitivity of the Logan Green area, they sought to get public buy in from an early stage by engaging the stakeholders in the decision making process. The result of this participatory decision-making process is an integrated project that solved the backwash water problem in an environmentally friendly way and created an recreational area for the community to enjoy. The second problem that Yorkton faced is the stormwater management. During the last decade, Yorkton experienced two major flood events in 2010 and 2014 that required declaring the state of emergency. Following the 2010 flood, the City started upgrading the infrastructure to reduce people’s vulnerability to future flood events. However, contrary to the backwash water problem, the City opted for a top down solution without seeking input from the public. The results show that the infrastructure upgrades did help in the 2014 flood, but they are not sufficient to flood proof the city against rainstorm events such as the one that happened in 2010.
Background
Yorkton, a city in Saskatchewan, enjoys a strategic1 location in east-central Saskatchewan, 190 kilometres away from the province’s capital, Regina, and 451 kilometres away from Winnipeg (City of Yorkton, n.d.-b) (Map 1). Yorkton’s history goes back to 1882 when settlers from Ontario, Manitoba and the British Isles established York City in the south-eastern part of Saskatchewan. Later it was named Yorkton, and it became a city in 1928 (City of Yorkton, 2020). Currently, Yorkton is one of the province’s largest cities with a population of 16,345 (2016) (the largest one being Saskatoon and Regina), comprising a land area of 36.32 square kilometres (Statistics Canada, 2017b).
Map 1, Esri ArcGIS
Figure 1 shows Yorkton’s population since 1991. It can be seen that after the slight decline in population between 1991-2006, the population started to increase rapidly after 2006. In fact, in the period 2006-2011, the population grew by 4.3%, and it is expected that Yorkton’s population will exceed 36000 people by 2036 (City of Yorkton, n.d.-b). This increase is mainly attributed to in-migration that is driven by the economic growth that the city is witnessing and the efforts made to attract an educated and skilled workforce from Canada and abroad (City of Yorkton, n.d.-a). The number of immigrants during the past four decades can be seen in Figure 2 which shows that the number of migrants has increased significantly.
Figure 1: Population of Yorkton
According to the latest labour data available from Census 20162 the unemployment rate in Yorktown in 2016 was 6.4%, which is lower than Saskatchewan’s rate of 7.1% and Canada’s rate of 7.7% for the same year (Statistics Canada, 2017b, 2017a). In the same year, only 8.47% of the workforce was self-employed (Statistics Canada, 2017b).
Yorkton’s economy is diversified, with many industries operating in the city. Collectively, those industries provide employment to over 8000 people (2016). As shown in Figure 3, the three biggest industries in 2016 were healthcare, retail trade and manufacturing, employing around 17.24%, 16.30% and 8.56% of Yorkton’s labour force, respectively. Comparing with the 2011 census, the two biggest industries in terms of employment were the same, although the number of people employed in health care grew by 20%, which improved its ranking, while the employment in retail trade slightly declined in 2016. With the construction of new plants in Yorkton and the expansion of the existing ones (City of Yorkton, n.d.-b), employment in manufacturing grew by around 43%, moving it from fifth place in 2011 to third in 2016.
Yorkton is highly accessible through a network of highways and railways in addition to a regional airport. It is close to important agricultural resources (City of Yorkton, n.d.-a). The government is making an effort to attract and retain regional and international investors, and it is encouraging businesses to expand (City of Yorkton, n.d.-a). Putting all these factors together, it can be said that Yorkton is in an excellent position to achieve considerable economic growth in the coming years.
The climate in Yorkton is humid continental with warm summers and cold winters. The temperatures range between -17.9 C and 18.2 C (City of Yorkton, n.d.-a). The annual precipitation is approximately 450.9mm (SaskAdapt, n.d.). Before 1980, the average yearly temperature was 1.2 C (Climate Data Canada, n.d.). Since then, the annual average temperature has increased by 1 C, and it is expected to increase further to reach 4.1 C within the next three decades (Climate Data Canada, n.d.). Similar to other parts of the world, climate change is expected to bring to Saskatchewan, and Yorkton, more extreme events like floods and droughts. This trend has already been witnessed in the province in the last decade with record-breaking temperature reported in different communities, unprecedented forest fires and alternating episodes of extreme flooding events and severe droughts that affected multiple communities throughout the province (Prebble, Asmuss, Coxworth, & Halliday, 2018).
Backwash Water Treatment and Community Solutions
For Yorkton city and its surrounding areas, groundwater is the only freshwater source (Maathuis & Simpson, 2006). The city receives freshwater for drinking and economic activities from five main aquifers located within and around the city (City of Yorkton, n.d.-c). The Department of Environmental Services in the City of Yorkton closely monitors those aquifers to ensure the quality and sustainability of the water supply. Raw water is extracted from 16 deep wells and pumped to Yorkton Water Treatment Plant, where it goes through a series of processes before it is distributed to the residents (City of Yorkton, n.d.-c).
The Yorkton Water Treatment Plant is relatively new; it was opened in 2012 (City of Yorkton, 2012). Before this plant was constructed, water was pumped from 14 wells to 4 small water treatment plants.
As those four plants were becoming old and incapable of meeting the current and future water needs of the growing population, the City of Yorkton elected to construct a new treatment plant which is capable of treating 33 million litres of water a day (the projected maximum day demand in 2030) when working in full capacity (Associated Engineering, 2011a). The construction of the new plant started in 2007, and phase I of the project, which is capable of treating a maximum of 22 million litres a day, was completed in 2011 (Associated Engineering, 2011a). The second phase will be constructed when the need for additional water treatment arises and will be treating the next 11 million liter of water which is feasible for meeting 30 years (projected life).
Backwash Water Treatment
In 2007, while the water treatment plant was under construction, the problem of backwash water treatment came up. Backwash water is the water that results from cleaning the filters (Water Security Agency, n.d.). Piping this water to the waste water plant, the way it was previously done, proved to be extremely costly, around $3 million, so the City started to consider other solutions that are more effective and less expensive (AWSA, 2012; City of Yorkton, n.d.-c). Eventually, it was decided that the backwash water will be treated onsite by constructing two settling ponds, a linear wetland that imitates the natural habitat and a fishpond (AWSA, 2012). The backwash water treatment process is simple and natural (Figure 4). It starts with releasing the water into the first settling pond where it settles for some time, it then goes to the second settling pond where it settles further. This process allows the contaminants, which are mainly iron and manganese particles, to sediment. A minimum of 24 hours settling time is required to satisfy the regulatory limits set by the Ministry of Environment (Associated Engineering, 2011a). After that, the water travels through the linear wetland to the fish pond which, in addition to being a recreational facility, serves as a proof of concept, demonstrating that the quality of the water is good enough to sustain life. After the fishpond, the water goes into infiltration pond where it recharges the aquifer. The materials that resulted from the construction of the pond were used to construct 6 sporting fields near the water treatment plant (City of Yorkton, n.d.-c). The total cost of the Logan Green System was $33 million. The City of Yorkton contributed $18.3 million and the rest was equally provided by the federal and the provincial governments (City of Yorkton, 2012).This project is considered a success by all city stakeholders as it employs an innovative, cost effective and environmentally friendly method to treat the backwash water. It created an eco-recreational area while saving the City over $3 million in infrastructure and $6.3 million in operational costs over the life of the plant (City of Yorkton, 2012).
Consequently, Yorkton received several awards for the implementation of the system including the Federation of Canadian Municipalities FCM Sustainable Communities award 2013, the Canadian Association of Municipal Administration CAMA 2013 Willis Award for Innovation, in the less than 20,000 population category, the Association of Professional Engineers and Geoscientists of Saskatchewan (APEGS) 2013 Environmental Excellence Award, 2013 Saskatchewan Municipal Award and the 2013 Innovative Technologies Award (City of Yorkton, n.d.-c).
Chronology of Events
In 2003 the City of Yorkton decided to employ Associated Engineering, consulting company, to evaluate the existing water treatment system and to prepare a study to upgrade it.
Associated Engineering completed the study in 2005 and recommended the construction of a new water treatment plant to replace the current plants.
The construction of the new water treatment plant started in 2007. At the same time, options for backwash water treatment were considered.
The first stakeholder meeting was held in March 2010, during which the participants reviewed the initial plan and discussed different components of the project.
Two other meetings were held in October of the same year.
The final meeting was held in May, 2011 during which the preliminary master plan was discussed.
In June 2011 the City of Yorkton held a community open house to introduce the project to the public and obtain their feedback.
The construction of the sedimentation ponds, linear wetland, fish pond and the soccer pitches started in August 2011.
Phase I of the plant was completed and commissioned in 2011.
The Logan Green Water Management System was officially open in June 2012.
Stormwater Management
While Yorkton has frequently suffered from water ponding in low lying areas, widespread flooding is not a common occurrence. According to the City’s Municipal History document, Yorkton experienced three floods prior to 2010 (City of Yorkton, 2020). However, since 2010, Yorkton experienced three floods, two of which were considered major, making the past decade one of the wettest for Yorkton.
The first one occurred on 1st of July 2010. The City of Yorkton declared a state of emergency3 after downpour had flooded the city and affected over 70% of the homes with more than 70 people being evacuated from their houses and over 900 Provincial Disaster Assistance Programs PDAP claims (Putnam, 2010; Wilger, 2010). The rainfall estimations ranged between 64mm and 150mm of rain, making it the highest record in over 50 years (AWSA, n.d.). The areas that were severely impacted by the flood include Broadway Street and the surrounding area, Dracup street, South end of Gladstone Avenue, Circlebrooke Drive and Riverside neighborhood (Wu & Nielsen, 2011).
Immediately after the flood, the City of Yorkton started making arrangements to reduce the vulnerability of people to future floods. This included commissioning Associated Engineering to conduct the Yorkton West Storm Drainage study and the construction of multiple ponds throughout the city (The Brodie Avenue pond, The Dracup Ponds and the Logan Green pond).
Exactly four years later, the City of Yorkton declared the state of emergency again as it experienced another major flood, but this flood was different. The rain was not as intense as the one that caused the 2010 flood but it lasted longer. As the water table was slightly elevated, sump pumps from homes around the city were releasing water into the sanitary system, which put an enormous pressure on the sewer system causing them to back up. In addition, because sump pumps at some low-lying locations had to work nonstop, they failed eventually and caused flooding in those basements.
The flood affected a number of houses and businesses and caused the closure of some highways including the highways to Saskatoon and Regina. However, the investment in storm-water infrastructure that the City made helped to reduce the intensity of the flood that would have been much more devastating without the upgrades (City of Yorkton, 2020). In 2016, the Yorkton flood mitigation study was conducted. This study covered the entire city and it identified 11 locations that require upgradation, some of them are already in progress while others are postponed until funding is available. The overall cost of the upgrade is estimated at around $40 million.
Chronology of Events
In 2006, a design for the Dracup Avenue ponds was prepared by Bullee Consulting LTD
On 1st of July 2010, the City of Yorkton declared the state of emergency as a result of a heavy rain that caused flood throughout the city.
In August 2010, the City proceeded to the design phase of the stormwater ponds on Dracup Avenue as identified by the 2006 study.
In October 2010, the City of Yorkton awarded the contract for the study and design of the Yorkton West Storm Drainage study to Associated Engineering
In January 2011, the City of Yorkton started considering the purchase of homes located on Brodie Avenue.
In May 2011, the Yorkton West Storm Drainage study (ref), which was prepared by Associated Engineering, was presented to the Council. The Council considered this study a long-term action plan that will be implemented as resources and funds become available.
The construction of the Logan Green dry bottom storm water detention ponds started in August 2011.
In October 2011, the construction of a dry bottom pond and the skatepark on Brodie Avenue started.
On 30th of June 2014, the City of Yorkton declared the state of emergency as a series of rain events caused sewer backup and localized flooding in some areas of the city.
January 2017, a flood mitigation study was prepared for the City.
The Research Process
To gain an in depth understanding of the water problems that Yorkton faced in terms of drinking water availability and flooding and the solutions that they implemented to reduce their vulnerability to future similar events, 11 semi structured interviews were conducted with people who were involved in the decision making process regarding the Logan GreenWater project and the infrastructure upgrades that the City of Yorkton implemented following the 2010 and 2014 floods (Refer to Appendix A for more info). The participants were identified based on the snowball sampling method, whereby each participant was asked to recommend another person for an interview. The interviews lasted between 45-90 minutes, all of them were conducted over the phone, recorded and transcribed. In addition to the information that the participants provided verbally, most of them had reports, presentation and other data that they volunteered to share with the researcher.
The questions were designed in a way that facilitated extracting information about the problems that the community faced, their impacts, the alternatives that were available at that time and the way the decisions to tackle those problems were made. Furthermore, some questions were concerned with the characteristics of the governance in Yorkton. For example, how decisions are made in general, who participates in this process, how autonomous are the participants, are resources and leadership available and how fair are the outcomes. These questions elicit crucial information about the context in which the decisions regarding the Logan Green project and the infrastructure upgrades were made.
Giving the fact that both the backwash water treatment project and the stormwater infrastructure upgrades started over nine years ago, it was difficult for the participants to remember the exact dates of some events. To overcome this problem, the City of Yorkton budgets (2010-2019), the City Council meetings minutes (2010-2011), the City Council meetings video recordings (2012-2019), Municipal History documents (2010-2019) and numerous Yorkton This Week articles discussing related issues were examined in order to acquire as much and as accurate information as possible.
Findings
Backwash water treatment
The problem of backwash water treatment came about with the City’s decision to construct a new water treatment plant. The water treatment process causes the accumulation of iron and manganese particles in the filters, which necessitates regular flushing using a reverse flow of water through the filter to remove those particles. The cleaning process is called backwashing. When operating on maximum capacity, the water treatment plant in Yorkton will be producing approximately 1100 cubic meters of water daily which is equivalent to 1.1 million liters of water, this resultant water is called backwash water.
At the beginning, the City considered treating the backwash water in the wastewater treatment plant, the same way it was previously done. This method would have required the construction of a force main, which is a pressurized pipeline, that is big enough to carry both the wastewater and the backwash water from the new water treatment plant to the existing gravity sewer system which in turn will convey this water to the wastewater treatment plant in the other side of the city. The capital cost of installing the pipes required to transfer the backwash water between the two plants, the operational cost and the maintenance cost over the life of the project would have cost millions of dollars. In addition to being extremely expensive, this option would have substantially increased the pressure on the existing wastewater treatment plant. Furthermore, giving the distance between the two plants, implementing the force main option would have required going through lots of logistics.
The City of Yorkton started looking for a way to treat the backwash water which would be more cost effective and environmentally friendly (ie not using any chemicals, creation of a recreation area). The idea of treating backwash water onsite using settling ponds came from the municipal Department of Environmental Services. But at that point it was not clear to them whether this idea was feasible, whether the community wanted it or whether it will be approved by the regulators. Hence, the Department of Environmental Services employed an Associated Engineering to conduct a feasibility study after receiving a grant from the Federation of Canadian Municipalities to fund this study (Associated Engineering, 2011a).
Logan Green is considered an environmentally sensitive area, due to the existence of a shallow aquifer (Associated Engineering, 2011a), and there was concern that implementing abackwash water treatment system there would be resisted by the community. For this reason, it was very important to have the community’s involvement from an early stage. To achieve this purpose, the Department of Environmental Services created a list of stakeholders that they thought would be interested in participating in the discussions and then they invited Assiniboine Watershed Stewardship Association to coordinate and mediate the meetings. The objective was to keep the City’s role as neutral as possible and to give the stakeholders the feeling that the City was looking for input and not dictating what it wanted to do. The Assiniboine Watershed Association refined the list of participants that was prepared by the Department of Environmental Service and invited those stakeholders to meet four times between March 2010 and May 2011 (A list of participants and their respective roles can be seen in Table 1).
The idea of treating backwash water onsite using settling ponds was expanded and consolidated through these meetings and consultations. The participants evaluated two design options. The first one involved the construction of a natural wet park with multiple storage ponds while the second one involved constructing a linear wetland through which water can flow from the settling pond to the east. Eventually, the study participants decided to implement the second option because it is less expensive, it does not take much land, allowing for other park uses and the moving water reduces the opportunity for mosquito breeding (Associated Engineering, 2011a).
In addition to the interest group consultations and meetings, the City of Yorkton organized a community open house with the objective of informing the public and obtaining their feedback regarding the plan which was positive with no changes suggested. After that the final plan was presented to the council, and it was unanimously approved. The construction began in August 2011 and the Logan Green Water Management System was open in June 2012. The result was an integrated project that includes a water treatment plant, two settling ponds, a stream, a fish pond, a dry bottom pond, and walking and cycling paths interposed with trees and shrubs (Map 2).
The backwash water treatment process is simple, natural and it has been working as intended with minimal maintenance. In fact, since the construction, the settling ponds required cleaning only once Around a foot and a half of sludge, mainly iron and manganese, was removed from the bottom of the first settling pond, while the second one had very little sludge accumulating in the bottom. Based on the City’s experience with the sedimentation ponds so far, it is expected that the cleaning will be done every three to five years.
It is worth mentioning that the cleaning of the settling ponds was not taken in consideration during the planning process, consequently, when cleaning was needed, the City did not exactly know how to do that. The process that they followed was that they diverted backwash water from the first settling pond to the second, then they drained the water as much as possible. After that, they used a submersible pump to dewater the iron and manganese that accumulated in the bottom of the pond. However, this process could not dry the sludge enough to be easily removed, so they decided to leave the sludge for some time to dry, which was however hampered by the wet weather conditions. Eventually, as the weather became colder, the sludge froze and they excavated and disposed it. Although the cleaning of the pond was not straightforward, the cost of the process was fraction of what the City would have to incur had they decided to construct the force main. Other than this issue, the participants reported no problem with this method. One participant described the process saying:”
“It is such a simple process, not very mechanical, so nothing to really break down. It is a settling pond with a couple of pipes; one coming in and one going out with a valve, so regular maintenance on those items and I think they will last for many years.” (CY1)
It is not expected that any upgrades will be required in the near future. The only thing that the participants mentioned is that if water demand increases substantially, which will increase the quantity of backwash water produced, there will be a need to construct a second fish pond. This additional fish pond was in fact taken in consideration in the initial plan.
Impetus and Success Factors
The City of Yorkton has managed to come up with and implement a cost effective and environmentally friendly solution to the backwash water problem that it was facing. What is interesting about this case is that the City managed to achieve these results not despite the budget constraints that it was having, but because of them. The high cost of constructing a force main to carry the water from the water treatment plant all the way to the wastewater treatment plant on the other side of the city has encouraged the City of Yorkton officials to consider innovative solutions to the backwash water treatment problem that they were facing. One of the participants described this by saying: “the budget did have a little bit of an effect it was more to identify that we did look at other options” (CY4). However, once it was confirmed that the sedimentation pond option was feasible, the budget was no longer the reason that made the City decide to implement it, the reason became all the benefits that this option provides to the community, compared to the first options, both in the short and the long run. When I asked one of the participants whether they would still go with the ponds option if they had the budget to construct the force main he said, “definitely the pond… even if it [the force main] was the same or cheaper. This is such a long-term zero maintenance project that not only does the facility benefit from it, it’s the whole community that benefits from this” (CY4).
While the tight budget has provided the impetus for environmental innovation, two factors have contributed to its success. The first one is the City of Yorkton Environmental Services department officials who have an environment oriented mindset and the desire to provide their citizens with the best possible service. They did not just look for a less expensive solution. They looked for an integrated solution that can address the problem in an efficient, economic, environmental and aesthetically pleasing manner. To put it in the words of the Director of Environmental Services in the first stakeholder’s meeting that was held in March 2nd 2010 “[We are] Looking for an award winning project with community involvement, marshlands, environment for wildlife, walking path, bike path, waterfall system, public education/awareness and recreation fields. Create a tourist attraction with strictly a water reuse project” (Associated Engineering, 2011a). Had the Department of Environmental Services staff had a different perspective on environmental issues, it is most likely that they would have looked into securing funds to finance the construction of the force main rather than trying to consider a different solution which combined community initiative with ecology and finances.
The second thing that contributed to the Logan Green water management system success is the participation of a wide range of stakeholders who contributed their ideas and expertise. It is still a widely prevalent practice that a government department comes up with a solution to a certain problem and then implements this solution without considering the perspectives of the people who are impacted by the problem or who may be impacted by the solution. While common, this approach to solving problems has proved to be inadequate. The Department of Environmental Services recognized the shortcomings of such an and the importance of including all the stakeholders in the decision making process. Hence, it prepared a preliminary plan based on the vision of what they wanted to implement and then held multiple meetings with stakeholders over a period of a year to refine this plan. It is worth noting that neither the interviews nor the review of the meetings minutes revealed any conflict among the stakeholders participating in those meetings. Provide some more information from the stakeholder’s viewpoint. This shows that the purpose of the meetings was not an attempt to find a common ground among the stakeholders or to resolve a conflict, the purpose was to get as much input as possible and to benefit from the expertise and knowledge of the involved parties in order to ensure that all aspects of the project are discussed and addressed in the best way.
Stormwater Management
The stormwater drainage system in Yorkton consists of two separate networks, the first one is the minor system network, which conveys the flows caused by the small and frequent events. The second one is the major system network, which carries the runoff caused by major rainstorms (Associated Engineering, 2011b). When the 2010 flood happened, the drainage system was over 30 years old and it was built to the standards of that period. Although the city had no flooding during minor rain events, the 2010 flood proved that the system is not capable of handling extreme rain events.
In addition to the fact that the drainage system is old and inadequate during major storms, other issues have exacerbated the 2010 flood situation. The Canadian Pacific and the Canadian National railways that cross the city of Yorkton are constructed on an elevated land compared to the surrounding area which restricts the flow of stormwater and creates a damming effect (Associated Engineering, 2011b).. Another issue that had a negative impact during the flood is the flat, or at some instances reverse, lot grading (Associated Engineering, 2011b). Ideally, the house must be higher than its immediate surrounding in order to ensure proper drainage. However, the improper lot grading in Yorkton caused runoff water to spill over curbs and move towards houses, cause flooding and damage to private property. In addition, there are many low lying locations throughout the city, which caused water to pond at these locations (Bullee Consulting, 2006).
Dracup Avenue Corridor
This study was prepared by Bullee Consulting LTD, an engineering firm, in 2006. Concentrating on the east part of the city, the study found that having a 1:25 year event would surpass the capacity of the drainage system and that water would pool in most low lying areas (Bullee Consulting, 2006). The study suggested that constructing water retention ponds is the most beneficial option arguing that having multiple small ponds located close to the contributing flow would perform better than one large pond (Bullee Consulting, 2006). Taking in consideration the costs associated with infrastructure upgrades and the future developments in the area, Bullee Consulting recommended constructing three retention ponds, two on the east and west side of Dracup avenue and the third south of Imperial Street (Daniels, 2010).
The study with its recommendations was presented to the Council in September 2006, however, no action was taken in this regard at that time. In August 2010, the council unanimously approved proceeding to the design phase of the stormwater ponds on Dracup Avenue as identified by the 2006 study. Constructing the ponds is projected to help the east side of the city in one-in-25 years to one-in-100 year events (Daniels, 2010).
Yorkton West Storm Drainage
The Yorkton West Storm Drainage study was awarded to Associated Engineering who used data provided by the City to develop a model that simulate the Yorkton West drainage area, including both the minor and major networks (Associated Engineering, 2011b).This model captures the surface runoff and its interactions with the underground piping network. Data on rainfall and flow was obtained from Saskatchewan Watershed Authority and used to calibrate the model.
Based on a review of stormwater system design standards adopted by different municipalities across the province, they recommended that the minor system in all new developments to be designed to handle 1:5 year events and the major system to be designed to handle 1:100 year events. While abiding by stringent standards in new developments is possible, it is very difficult and expensive to do in old and existing areas. Consequently, the target for the existing system is that pipes do not surcharge during 2-year events, manholes do not flood during 5-year events and run off water does not spillover the curb during 25-year events. Associated Engineering analysed the performance of the existing system. The analysis showed that over two thirds of manholes do not meet the suggested 5-year event standard, 12% of manholes do not meet the 5-year event target and 11% of street nodes do not meet the 25-year event target.
After trying different combinations of upgrades Associated Engineering recommended an extensive upgrade of the sewer system which includes adding stormwater management ponds, replacing and upgrading some culverts, re-grading the Victoria Avenue ditch system, upgrading the storm mains along different avenues and streets and connecting the Brodie Avenue system with the Victoria Avenue ditch system (check Appendix B for the detailed recommendations). Implementing these upgrades is supposed to significantly alleviate flooding in different areas of the city and reduce the extent and depth of flooding in the areas that will continue to be flooded. The total cost of the upgrades was estimated to be around $15 million which will be split over multiple years.
On 30th of May 2011, this extended concept upgrade was presented to the City Council. The study was accepted and considered a long term action plan that will be implemented as funds and resources become available.
The stormwater pond that the study recommended is on Brodie Avenue, which is one of the hardest hit areas in the city. The properties along Brodie Avenue was damaged beyond repair and the area was identified as flood prone. To avoid future flooding in the neighborhood, the City bought out properties on Brodie Avenue, demolished them and prepared to convert the area into a 8,700 cubic meters dry bottom pond that can hold water and relieve pressure on downstream drainage system in the event of a storm. (Daniels, 2011a, 2011b). However, with community involvement, the plan was expanded as the skateboarding community of Yorkton with local initiatives submitted a proposal to Aviva Community Fund contest for a $150,000 award that would go towards the construction of a skateboard park in the area, which they won in January 2012 (Benjoe, 2012; Putnam, 2011). The City matched this amount and an additional $50,000 came from the Community Initiatives Fund (Wilger, 2012) and the full amount was invested in the design and construction of the Skateboard park. The once flood-damaged location was transformed into a recreational area that includes a skating park, water retention pond, greenery and walking paths (Benjoe, 2012).
Discussion
Flood Mitigation Study
This study was conducted by Integrated Engineering, a consulting engineering firm who presented their findings and recommendations to the City of Yorkton Council on 30th of January 2017. What is unique about this study is that it is the first study to cover the entire city, which provides a better understanding of how changes in a certain location can impact drainage in other areas. Integrated Engineering used a modeling software, the data from the LIDAR survey that was performed in 2016 and the information provided by the Public Works department on problem areas in the city in order to identify the causes of the flooding in these areas.
The report indicated that most of the problems were happening in low lying locations and that the railways were also contributing to flooding problems. To solve those problems, Integrated Engineering recommended a list of upgrades that includes channel upgrades, diversion ditches and detention ponds- explain in footnotes (Appendix C). Some of these upgrades needed to be done in a certain order for the city to get the best results. Other upgrades can be done at any time with no particular order. The total cost of the upgrades is estimated to be around $40 million, however, this estimate does not include the cost of land acquisition that some upgrades require.
Impetus for change
Despite the significant costs associated with upgrading the drainage system, flood mitigation became a priority of the City’s agenda. This change in priorities is driven by change in perspective. Because of the geographic location of the City of Yorkton, its climate and the fact that it did not experience any floods for over 30 years prior to 2010, its residents considered Yorkton a place that does not get flooded. And although there were studies prepared since 2006 to improve the city’s stormwater infrastructure, these studies were not implemented as there was no pressing need to make changes and there were other things on the list that had higher priority. As one of the participants puts it “It’s pretty hard to obtain Major funding for stormwater projects if the flood never occurred” (CY4). The 2010 flood and the extreme events that followed made people change their perspective. Yorkton is now considered a flood-prone area, consequently, upgrading the drainage system became a priority. One of the participants explained this point by saying that “the priority is kind of tends to change depending on recent weather and that’s part of the challenge” (CY2).
Besides, the recurrence of floods has created political pressure for change. Although neither one of the two floods caused any fatalities, the disruption and the financial losses that it caused were substantial. Some people had to repair their properties and throw all the belongings that were in contact with water. Many businesses were closed for months others have temporarily relocated their operations to other locations while their main locations were being repaired. Some people lost their homes and businesses forever, as they were damaged beyond repair. In addition, the flood has caused health problems to people who were in contact with the mold that was caused by the dampness. The difficulties that the residents of Yorkton had to go through during the flood were substantial enough to make people fear going through a similar event again and they conveyed these concerns to the Council and the Mayor. One of the participants noted that “on years where we have several bad thunderstorms you know our politicians are very eager to do something about it” (CY2).
Important notes about the upgrades
Although the upgrades that have been done to the stormwater system since 2010 has reduced the risk of flood, all the upgrades that have been done so far and all the upgrades that are planned for the future are not sufficient to completely proof the city against flooding in case of extreme events such as the one that happened in 2010. Based on financial feasibility and the fact that most of the upgrades are done at existing development, it was decided that the upgrades are done to handle 1 in 100 year events. The probability of the 2010 event recurrence was decided at 1 in more than 100 years (Wu & Nielsen, 2011). In other words, if a storm of the same magnitude as the 2010 one happens again, the city will be flooded, however, it is expected that the flood will be less severe. However, it is worth noting that those upgrades are already extremely expensive. Making upgrades for events that are more extreme than 1:100 will be even more expensive and may not be implemented due to budget constraints.
Another thing is that although the upgrades that have been done since the 2010 flood have helped in mitigating the impact of the 2014 flood, these upgrades are meant to deal with the 2010 type of event, which is a heavy rainfall over a short period of time, not with the 2014 type of event, which is a less severe rain that falls over a prolonged period of time causing a higher water table and sewer backup.
Conclusion
This study examine two different water problems that the city of Yorkton faced and the way those problems were approached. Treating the backwash water on-site using sedimentation ponds saved the city close to $10 million in infrastructure, operational and maintenance costs over the project’s life. The project has been working as intended with no reported problems and with minimal maintenance requirements. Besides, it offered an environmentally friendly solution to the problem they faced while creating a recreational area for the community to enjoy with trees, settling ponds, a fish pond, sports fields, and walking and cycling trails. For these reasons, this project is considered successful.
The infrastructure upgrades that the City has made reduced people’s vulnerability to future flood events, and they utilized some Low Impact development projects such as the retention ponds. However, there are some shortcomings. For example, the upgrades do not completely flood proof the city and there was no public engagement. While the former project can be easily classified as a best water management practice, judging the latter project is not so straightforward.
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List of Participants
Appendix B
Extensive upgrade concept recommended by Associated Engineering for the Yorkton West Drainage Study
This option Includes:
Lowering the Victoria Avenue ditch by 1.4 m at the outlet just north of Smith Street.
Re-grading the 1.4 km Victoria Avenue ditch system to Hwy 16A (York Road).
Replacing eight culverts along the Victoria Avenue ditch system.
Upgrading the culvert crossing across Highway 16A (York Road).
Upgrading the storm mains along Melville Avenue, Haultain Avenue, Broadway Street West, Maple Avenue, Smith Street West, Laurier Avenue, and Brodie Avenue.
Increasing the inlet (catch basin) capacity in the Brodie and Broadway areas.
Adding a new storm sewer line to provide connectivity between the Brodie Avenue system and the Victoria Ave ditch system.
Adding a surge pond immediately east of Brodie Avenue.
Appendix C
Flood Mitigation Plan Costs and Construction Summary
