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HomeMy WebLinkAboutDTS-10-126 - Grand River Slope Stabilization - Class Environmental Assessment (EA) Addendum REPORT REPORT TO: Development and Technical Services Committee DATE OF MEETING: June 21, 2010 SUBMITTED BY: K. Grant Murphy, P.Eng., Director of Engineering Services PREPARED BY: Kevin Mick, P. Eng., Design and Approvals Engineer WARD(S) INVOLVED: Ward 2 DATE OF REPORT: June 14, 2010 REPORT NO.: DTS 10-126 SUBJECT: GRAND RIVER SLOPE STABILIZATION - CLASS ENVIRONMENTAL ASSESSMENT (EA) ADDENDUM RECOMMENDATION: THAT the Grand River Slope Stabilization Class Environmental Assessment Addendum Report prepared by MTE Consultants Inc., dated June 2010 be received; and That the Grand River Slope Stabilization Class Environmental Assessment Addendum Report be filed with the Ontario Ministry of the Environment for the mandatory thirty (30) day review period as required by the Environmental Assessment Act; and further; That staff be directed to commence the implementation of the recommendations of the Class EA Addendum, following the thirty (30) day mandatory review period and Ontario Ministry of the Environment acceptance of the study, through the Capital Budget. EXECUTIVE SUMMARY The City initiated a Class Environmental Assessment Addendum study in 2010 to explore alternatives and prepare a preliminary design to address the slope stability issues that currently exist on the Grand River in the Chicopee Vale subdivision adjacent to the properties between 307 and 331 Grand River Boulevard and from 81 to 97 Manitoulin Crescent. The study explored various solutions and evaluated each on defined criteria to determine a preferred alternative. The preferred alternative for the Grand River Slope Stabilization is Alternative 3 – Construct/Install Remedial works to intercept groundwater, collect surface water and stabilize slope and toe erosion. The main features of this alternative are the installation of a new groundwater and surface water collection system, complete with a new outlet, a vegetated reinforced earth retaining system along the top one-third of the slope and vegetated rip-rap along the toe of slope. These main features are recommended to be constructed on city owned property. è è ó ó ï ï BACKGROUND: In 2010, MTE was retained by the City of Kitchener to provide an update to an existing Environmental Study Report (ESR) prepared by Environmental Water Resources Group Ltd. in relation to the failing slope along Grand River Boulevard/Manitoulin Crescent in the Chicopee Vale subdivision. The study area is located along the Grand River approximately 3.0 km upstream of the King Street East and CN Railway crossings. It is situated on the outside of an eroding meander bend and the bank heights are approximately 35.0 m. The Chicopee Vale subdivision is located at the crest of the slope with directly affected residents located between 307 and 331 Grand River Boulevard and from 81 to 97 Manitoulin Crescent. The homes are located within 25 m of the slope crest with approximately 10 m of land between the rear property line and the slope crest. There is also a public pedestrian trail along the top of the slope. The length of the eroding slope is approximately 175 m. In 1992 residents affected by this problem requested help from the City of Kitchener (City) to find a solution, after a significant amount of soil and large trees had moved down the slope. The request prompted the initiation of the initial ESR. Consequently, in 1996, the Grand River Conservation Authority (GRCA), through their consultant, completed the Grand River Slope Stabilization Study - ESR. The report was submitted and accepted but none of the recommendations for remediation were implemented. In 2010, the City, having re-prioritized the need for erosion and stabilization measures along the Grand River to minimize the risk to public safety and to private property, retained MTE Consultants Inc. to review the original 1996 ESR and conduct a study to confirm or develop new alternatives for remediation following the course of action set out in the Municipal Environmental Assessment (MEA) process. REPORT: The City initiated a Class Environmental Assessment Addendum study to explore alternatives and prepare a preliminary design that addresses the slope stability issues that exist on the Grand River in the area of Chicopee Vale Subdivision, in a manner that complies with Ontario’s Environmental Assessment Act. A project team was formed and comprised of City staff and Consultant staff with expertise in different fields, such that the project could be evaluated from multiple standpoints. The main objective of the study is to determine a preferred option for this area of the Grand River with respect to slope stability issues, while taking into account: Natural and physical components of the environment Affects on residents and neighbourhoods Costs Operations and maintenance Constructability Land requirements Ability to Implement The Municipal Class Environmental Assessment Document (June 2000, as amended in 2007) defines “alternative solutions” as: è è ó ó î î “feasiblealternative ways of solving an identified problem (deficiency) or addressing an opportunity, from which a preferred solution is selected”. Based on the opportunities and constraints analysis, alternative solutions were identified and evaluated on project-specific evaluation criteria which covered five criteria categories as follows: Technical environment Natural environment Social/Cultural environment Economic/Financial environments Legal/Jurisdictional environments Alternatives Solutions The following alternative solutions were identified as being feasible ways of addressing the slope stability issues associated with this area. Alternative 1 - Do Nothing As part of the Class EA process, the “Do Nothing” alternative solution must be considered. For this project, “Do Nothing” would have the following implications: The slope will continue to fail There will be continued loss of trees, vegetation and habitat There will be a loss of the trail There will be a loss of aesthetic value and possible reduced property value Alternative 2 - Purchase of the Properties Most Adversely Affected This alternative has the following implications: The slope will continue to fail There will be continued loss of trees, vegetation and habitat There will be a loss of the trail Ultimately the homes will be removed and alternative uses created for these lands (Preferred Alternative) Alternative 3 – Construct/Install Remedial Works This alternative has the following implications: This alternative consists of various components that would consist of works to address problems related to surface water drainage; the groundwater elevations and their seepage onto the slope area creating slope instability; erosion of the toe of the slope by the river; and the over-steepened and instable top of slope area There will initially be loss of trees, vegetation and habitat on portions of the lands located between the property line and top of slope, upper slope and toe areas to construct the works but a re-vegetation plan will be part of the proposed rehabilitation è è ó ó í í Within Alternative 3 above, there were several combinations of each of the components that were reviewed. For example, to intercept groundwater, one option would be to collect the groundwater at the fronts (i.e. road side) of the properties and then pump it to the storm sewer. Another option would be to collect the groundwater on the rear of the properties and either pump it up to the storm sewer system at the road or discharge the waters directly to the Grand River. However, to address the other problems that exist in this area, additional works would still have to be done on or near the slope area (eg. surface drainage water collection and slope regarding or reinforcement). Consequently, a solution to address groundwater issues appeared best to fit with other components that would best address slope instability and surface water concerns and that it should be located in the same general area as those other components. As with, the groundwater components, several options also existed for the collection of surface drainage water, upper slope regrading or reinforcing and the protection of the toe of the slope along the river’s edge. Some of the factors that were considered in evaluating the components were: whether or not encroachments onto private property would be required; whether or not the location of the works would provide optimal effectiveness; what would be the environmental impacts; and the effects on aesthetics, both long and short term (eg. selection of vegetated rip-rap and reinforced earth solutions). Each of the above alternatives were evaluated based on their benefits in the five criteria categories (technical, natural, social/cultural, economic/financial and legal/jurisdictional) and were rated to determine the preferred solution. Using the ratings the preferred solution for the Grand River Slope Stabilization is Alternative 3 – Construct/Install Remedial works to intercept groundwater, collect surface water and stabilize slope and toe erosion. This alternative consists of the following elements: Construct a groundwater interceptor trench of sufficient depth along the City-owned lands between the rear property lines and the top of bank to intercept groundwater before it reaches the slope face and creates the instability in the upper one-third of the slope area; Construct a surface drainage system designed to be ancillary to, and in the same general area as, the interceptor trench in order to pick up the surface drainage water flowing from the rear portions of the lots, the slope crest area and other portions of the watershed area; Redirect the eavestrough downspouts from the affected homes fronting on Grand River Boulevard and Manitoulin Crescent so as to discharge toward the roads instead of to the rear of the properties and the slope area; Construct a new closed outlet down the slope area to the Grand River which would serve as the outlet the interceptor trench and the surface drainage system; Construct a vegetated reinforced earth retaining system along the majority of the top one-third of the slope area to stabilize the top of slope and at the same time, minimize as much as is possible the removal of existing vegetation. It is noted that notwithstanding this work, there will still be vegetation loss in order to gain slope stability; è è ó ó ì ì Construct protection consisting of vegetated rip-rap along the toe of the slope at the level of the Grand River in order to arrest erosion that is currently occurring along this westerly (outside bend) portion of the river’s bank; and Re-establish the trail path and plant vegetation along the slope area and top of slope area to provide a vegetative screen between the properties and the trail area as well as to provide new vegetation to replace as is practical the vegetation removed necessitated by construction of the erosion control work. Proposed Sequence of Implementation City staff is proposing the following sequence for the implementation of the recommendations: Completion of 30-day review (July 2010) Detailed design (July - August 2010) Permitting (August – September 2010) Construction of preferred alternative (Fall 2010 – Summer 2011) FINANCIAL IMPLICATIONS: Work completed to date on the Class EA has been accommodated in this project’s capital budget account. The estimated cost of implementing recommendations of the study is $5,500,000. This amount includes construction costs and consulting fees. The current approved budget for this project is $4,000,000. This amount was based on the original study and inflationary adjustments. The current budget is sufficient to implement a significant number of the study’s recommendations. However, the work will likely be staged over the 2010 and 2011 construction seasons, and adjustments to the 2011 budget will be made as part of the next budget cycle to accommodate the remainder of the work. COMMUNICATIONS: A Notice of Commencement was published in the KW Record and was sent to a mailing list of interested individuals. Two Public Information Centres (PIC) were held as part of this project. The first PIC was held in May 2010 and the second in June 2010. The PIC’s were advertised through newspaper and invitations were delivered to area residents. Both PIC’s were held at Howard Robertson Public School. Input was also solicited from various utilities and government agencies through written correspondence and telephone conversations. Due to the nature of this project, two resident meetings here held with homeowners that were directly affected by the slope stability issue. The purpose of these meetings was to engage in discussions and solicit feedback with those members of the public with a more direct stake in the project. è è ó ó ë ë CONCLUSION: The completion of the Grand River Slope Stabilization Class Environmental Assessment Addendum study has established a preferred alternative to address the slope stability issues that exist along the Grand River in the Chicopee Vale Subdivision. The preferred alternative is identified as Alternative 3 – Construct/Install Remedial works to intercept groundwater, collect surface water and stabilize slope and toe erosion. The main features of this alternative are the installation of a new groundwater and surface water collection system, complete with a new outlet, a vegetated reinforced earth retaining system along the top one-third of the slope and vegetated rip-rap along the toe of slope. These main features are recommended to be constructed on city owned property. Timing for the implementation of the recommendations will commence upon completion of the thirty (30) day mandatory review period and Ontario Ministry of the Environment acceptance of the study. ACKNOWLEDGED BY: Jeff Willmer General Manager, Development and Technical Services è è ó ó ê ê June 17, 2010 Grand River Slope Stabilization – MTE Project No. 34273-100 1.0EXECUTIVE SUMMARY In 2010, MTE was retained by the City of Kitchener to provide an update to an existing Environmental Study Report (ESR) prepared by Environmental Water Resources Group Ltd. in relation to the failing slope along Grand River Boulevard/Manitoulin Crescent in the Chicopee Vale subdivision. The study area is located along the Grand River approximately 3.0 km upstream of the King Street East and CN Railway crossings. It is situated on the outside of an eroding meander bend and the bank heights are approximately 35.0 m. The Chicopee Vale subdivision is located at the crest of the slope with directly affected residents located between 307 and 331 Grand River Boulevard, from 81 to 97 Manitoulin Crescent and 57 and 61 of Tinatawa Court. The homes are located within 25 m of the slope crest with approximately 10 m of land between the rear property line and the slope crest. There is also a public pedestrian trail along the slope face. The length of the eroding slope is approximately 250 m. In 1992 residents affected by this problem requested help from the City of Kitchener (City) to find a solution, after a significant amount of soil and large trees had moved down the slope. The request prompted the initiation of the initial ESR undertaken by the Grand River Conservation Authority as a Class Environmental Assessment for Remedial Flood and Erosion Control projects. Consequently, in 1996, the Grand River Conservation Authority (GRCA), through their consultant, completed the Grand River Slope Stabilization Study - ESR. The report was submitted and accepted but none of the recommendations for remediation were implemented. In 2010, the City, having re-prioritized the need for erosion and stabilization measures along the Grand River to minimize the risk to public safety and to private property, retained MTE Consultants Inc. to review the original 1996 ESR and conduct a study to confirm or develop new alternatives for remediation following the course of action set out in the Municipal Environmental Assessment (MEA) process. As this project follows the Class “B” EA process, the City as the proponent, is required to undertake a screening process involving mandatory contact with directly affected public and relevant review agencies. Two public information sessions have been held and information has been circulated to the affected residents as well as the public and various agencies. In addition, a formal notice of commencement and public advertising were completed. The project team has reviewed existing documentation and conducted field work to determine the existing conditions and establish the extent of work that would be required. The work included topographic survey and hydraulic, geotechnical and environmental field and desktop reviews. è ó é The review of conditions identified four (4) major contributing factors influencing the slope failure. These were identified as groundwater seepage onto the slope face, the collection and discharge of surface drainage waters onto and over the slope area, the over-steepened and eroding upper bank area and the erosion of the toe of the slope at the edge of the Grand River. The project team has identified three alternative solutions for remedial works ranging from the “do nothing” approach, to purchase of the homes most threatened, to a compilation of various remedial solutions. A chart illustrating the various alternative solutions is shown below: ALTERNATIVE COMMENTS 1.0 Do Nothing The slope will continue to fail There will be continued loss of trees, vegetation and habitat There will be loss of trail There will be loss of aesthetic value and reduced property value 2.0 Purchase of The slope will continue to fail Properties Most There will be continued loss of trees, vegetation and Adversely Affected habitat There will be loss of trail There will be loss of homes creating the necessity for families to relocate Ultimately the homes will be removed and alternative uses created for these lands 3.0 Construct/Install This alternative consists of various components that Remedial Works would consist of works to address problems related to surface water drainage; the groundwater elevations and their seepage onto the slope area creating slope instability; erosion of the toe of the slope of the river; and the over-steepened and instable top of slope area There will initially be loss of trees, vegetation and habitat on portions of the table lands, upper slope and toe areas to construct the works but a re-vegetation plan will be part of the proposed rehabilitation There will be temporary loss of trail but its re- instatement will be part of the proposed rehabilitation Within Alternative 3.0 above, there were several combinations of each of the components that were reviewed. For example, to intercept groundwater, one option would be to collect the ground water at the fronts (i.e. road side) of the properties and then pump it to the storm sewer. Another option would be to collect the groundwater on the rear of the properties and either pump it up to the storm sewer system at the road or discharge the waters directly to the Grand River. However, to address the other problems that exist in this area, additional works would still have to be done on or near the slope area (eg. surface drainage water collection and slope regarding or reinforcement). Consequently, a solution to address groundwater issues appeared best to fit with other components that would address slope instability and surface water è ó è concerns and that it should be located in the same general area as those other components. As with the groundwater components, several options also existed for the collection of surface drainage water, upper slope regrading or reinforcing and the protection of the toe of the slope along the river’s edge. Some of the factors that were considered in evaluating the components were: whether or not encroachments onto private property would be required; whether or not the location of the works would provide optimal effectiveness; what would be the environmental impacts; and the effects on aesthetics, both long and short term (eg. selection of vegetated rip-rap and reinforced earth solutions). Review of the various alternatives and their components (refer to attached Evaluation Matrix), identified a preferred alternative for the remedial measures. The elements of this preferred alternative have been identified. They are illustrated on the attached Figure 3.1 and are outlined briefly below: 1. Construct a groundwater collection system along the City-owned lands between the rear property lines and the top of bank to intercept groundwater. The collection system will extend to a depth of approximately 5m; 2. Construct a surface drainage system designed to be ancillary to, and in the same general area as, the interceptor trench in order to pick up the surface drainage water flowing from the rear portions of the lots and the slope crest area; 3. Redirect the eavestrough downspouts from the affected homes fronting on Grand River Boulevard and Manitoulin Crescent so as to discharge toward the roads instead of to the rear of the properties and the slope area; 4. Construct a new closed outlet down the slope area to the Grand River which would serve as the outlet the groundwater collection system and the surface drainage system; 5. Utiilize vegetated reinforced earth stabilizing technology system along the majority of the top one-third of the slope area to stabilize the top of slope and at the same time, minimize as much as is possible the removal of existing vegetation. It is noted that notwithstanding this work, there will still be vegetation loss in order to gain slope stability; 6. Complete toe protection along the base of the slope with vegetated large rip-rap. This will be completed at the level of the Grand River in order to arrest erosion that is currently occurring along this westerly (outside bend) portion of the river’s bank; and 7. Re-establish the trail path and plant vegetation wherever possible to provide a vegetative screen between the properties and the trail area as well as to provide new vegetation to replace the vegetation removed necessitated by construction of the erosion control work. è ó ç It is expected that construction of the works may take approximately 14 weeks. However, phasing of the works to be done may be required due to the timing of approvals, construction timing and budget planning. The phasing would be construction of the outlet works; construction of the erosion protection at the top of the slope area; and finally, the construction of the toe protection along the bank of the Grand River. The cost for the project has been estimated as approximately 5.5 million dollars. è ó ïð è ó ïï è ó ïî