Chines Integrated Stormwater (Watershed) Managerrient Plan

Transcription

1 Coouitlam Fof Counci June 13, 2016 Our File: /000/ Doc#: V1 To: From: Subject: For: City Manager General Manager, Engineering and Public Works Chines Integrated Stormwater (Watershed) Managerrient Plan Council Recommendation: That Council: 1. Adopt the final report of the Chines Integrated Stormwater Management Plan dated May 2016; and 2. Refer the recommended stormwater improvements in the plan to the City's capital budgeting process. Purpose: The purpose of this report is to seek Council's adoption of the Chines Integrated Stormwater Management Plan (ISMP). The executive summary of the plan is shown in Attachment #1, and a copy of the full plan is available for viewing in the Clerk's office. Strategic Goal: This plan supports City goals of strengthening neighbourhoods and enhancing the sustainability of City services and infrastructure. Background: The Chines ISMP is a Joint study with Port Moody and Metro Vancouver that covers a collection of small watersheds flowing into the Burrard Inlet. Metro Vancouver manages the trunk drainage mains and watercourses in the Chines area. The term Integrated Stormwater Management Plan (ISMP) is used by some other jurisdictions, but the City uses the term Integrated Watershed Management Plan (IWMP) to acknowledge the interconnected elements of a watershed which impact drainage patterns and watercourse health. The draft report of the Chines ISMP was received by Council on December 7, 2015, (Attachment #2), and a copy of the draft plan was made available on the City's website. The City of Port Moody met with stream stewardship groups earlier this year and received general support for the plan. The final report reflects input from

2 Page 2 June 13, 2016 stream stewards, a technical committee representing Port Moody, Metro Vancouver and Coquitlam staff, and an engineering consulting team. Discussion/Analysis: The Chines is an urban watershed straddling the cities of Coquitlam and Port Moody. The area contains a number of streams which remain in a relatively natural state on forested escarpment slopes. Within the upland and lowland areas, where there is substantial residential and industrial development, the watercourses are piped and rerouted to centralized discharges at Burrard Inlet. The objective of the plan is to gradually improve the overall health of the watershed over time and prevent further degradation from new development. There is no new land development anticipated in the Coquitlam portion of the watershed, but some development activity is occurring in Port Moody along the Evergreen line. Recommendations, summarized in the Executive Summary table, include measures for slope stability, erosion prevention, flood protection, pipe capacity upgrades, rainwater management, and environmental enhancements. The City's Rainwater Management Requirements are recommended for new developments in the watershed, consistent with other IWMP's. However, due to the prevalence of steep slopes, only detention storage and release into storm sewers will be used for source controls until a groundwater monitoring study can identify safe areas for infiltration. Opportunities for enhancing aquatic habitat that are identified in the plan may be implemented as habitat compensation for capital works or land development impacts. Engineering and Public Works staff will also be using outreach programs to educate the public about private property impacts to watershed health. As part of this plan, a qualitative landslide risk assessment was conducted by a professional geologist. Properties in the Chines area with a higher landslide risk were further assessed by a geotechnical engineer and determined to have an acceptable factor of safety against slope failure. File#: /000/ Doc#: V1

3 Page 3 June 13, 2016 Financial Implications: Coquitlam's portion of the Chines IWMP improvements are estimated at $2.7 million for upgrades to the piped system. Capacity upgrades will be phased with replacement of ageing infrastructure through the Asset Management Program and referred to the City's long range capital budgeting process. Conclusion: Development and implementation of IWMP's will improve flood protection in the City while protecting natural assets and improving watershed health overtime. Jo^f Dioszegh^ P.Eng^ Attachments: ^ 1. Chines ISMP Executive Summary 2. Council report titled, "Mundy and Chines Integrated Watershed Management Plans" dated November 16, 2015 This report was prepared by Melony Burton, AScT, Supervisor Infrastructure Management and reviewed by Dana Soong, P.Eng., Manager Utility Programs. File#: /000/ Doc#: V1

4 ATTACHMENT#! CoQuitlam Chines Integrated Stormwater Management Plan C it If tif till- /\ i t> Final Report metro Vancouver Associated Engineering GLOBAL PtRSPiCrm. LOCAL FOCUS. May 2016

5 J REPORT ATTACHMENT#! Executive Summary Metro Vancouver, in partnership with the City of Coquitlam and the City of Port Moody, engaged Associated Engineering to develop an Integrated Stormwater Management Plan (ISMP) for the Chines watersheds, which include the Port Moody-Coquitlam Drainage Area (managed by Metro Vancouver) and the Suter Brook and Pigeon Creek sub-watersheds, managed by the Cities. Metro Vancouver is only responsible for the main stems of the creeks and the major piping system. ISMP Objectives The objectives of the Chines ISMP are: Key Issues Manage runoff to reduce erosion activity in the ravines. Implement measures to improve water quality. Enhance aquatic and terrestrial habitat, including identification of long term strategies for partial stream daylighting. Identify and recommend the use of green infrastructure to manage rainwater through volume and peak flow reduction and the improvement of water quality. Provide improvements in aesthetics/livability within the ISMP. Address any flooding risks. Address the increase in impervious surfaces and runoff associated with future development by promoting control of rainfall onsite to reduce the need for additional hard infrastructure. Develop a landslide risk analysis methodology and implementation of a landslide partial risk analysis. The key issues are: The Chines ravine slopes are generally steep and slope stability is a concern. With the Evergreen Line planned to bisect the lower portion of the watershed, redevelopment of the City Centre area of Port Moody is anticipated. Flooding issues are limited and generally occur when debris blocks the intakes to the pipe system at the outlet of the ravines in Port Moody. Recommendations and Costs The recommended action items and cost estimates for the Chines watershed are summarized in Table ES-1.

6 ATTACHMENT#! Metro Vancouver Table ES-1 Summary of ISMP Recommendations Section Actions Cost Timeline Potential Lead Agency or Primary Responsibility Source Control Standards and Implementation 7.1 Enact and enforce the detention criteria discussed in Section 7.1. Potentially applicable BMPs are identified in Section 6.2, and should be selected as appropriate for each site. < $50, The City of Port Moody should adopt equivalent standards or guidelines for rainwater management as discussed in Section 7.1. < $50, Develop and implement an education and outreach program to encourage implementation, retention and maintenance of source controls. Infrastructure Improvements Upgrade minor pipe systems in uplands $2,700,000 Long City of Coquitlam $1,800,000 ($1,100, Upgrade minor and major pipe systems in lowlands. with optional daylighting of Clark Rd Tributary of S. Long City of Port Moody Schoolhouse Creek) Upgrade deficient major trunk drainage pipes. $250,000 Long Metro Vancouver Divert high flows if required to mitigate impacts to ravines. $7,000,000 (order of magnitude) Long Metro Vancouver 7.4 Upgrade hydrometric monitoring stations (three stations) with direct flow measurement and real time telemetry. $120,000 ($40,000/station) 5 years Metro Vancouver 11 p:\ \00_isnnp\engineering\03.02_conceptual_feasibility_report\phase 6\rpt_mv_masterjsmp_final_ _mm.docx

7 ATTACHMENT#! Executive Summary Section Actions Timeline Potential Lead Agency or Primary Responsibility ^Environmental Enhancements Clear accumulated garbage and debris at culvert/pipe inlets. < $50, Clear accumulated urban refuse and other debris from the ravine corridors. < $50,000 Stabilize or remove erosion sites and fine sediment deposits that decrease or impact available habitat for juvenile Varies with site salmonids and benthic invertebrates. Control or re-route runoff from heavy rainfall events that destabilize creeks Site dependant resulting in loss offish habitat. Develop plans for construction of pools and riffles in suitable fish accessible creek reaches to provide additional $50,000 overwintering and rearing habitat. Remove invasive plant infestations in interface areas between the ravines and residential development. $200,000 (order of magnitude) Implement education efforts to discourage disposal of garden wastes or < $50,000 residential refuse into the ravines Add spawning gravels to creeks. < $50,000 ft'':-:, T ' V I. Lowland creek daylighting and restoration per outcome of feasibility study (see below). indeterminate, but significant depending on scope Varies with opportunities, but should be a priority Metro Vancouver/Port Moody I Limit further enclosure of open channel drainage components (ditches and ffp 'r swales). Provide compensating rainwater management features for lost minor Immediate Both Cities iii

8 ATTACHMENT#! Metro Vancouver Section Actions Cost Timeline Potential Lead Agency or Primary Responsibility hydrological function. Studies, Evaluations and Ongoing Efforts Conduct a feasibility study on dayiighting lowland portions of Dallas Creek. $50,000, Metro Vancouver/Port Moody Conduct a feasibility study to examine 7.3 the replacement of the sediment basins $50,000 Metro Vancouver at the Goulet intake. Conduct a groundwater monitoring study 7.1 to determine suitable areas for infiltration. $200,000 per city. Both Cities, Priority for Coquitlam Develop and implement a monitoring and adaptive management process based on 7.4 the recommendations of Section 7.4. Coordinate efforts of the Cities and Metro Varies with selected level of effort. - Ongoing Vancouver. Ensure Operations and Maintenance 7.5 activities and responsibilities for BMPs are identified and followed accordingly. Varies - Ongoing Rainwater Management Criteria The Chines watershed rainwater management criteria are summarized in the table box below: Rainwater source controls in the Chines watershed should be designed to limit the 2-year post-development peak flow to 50% of the 2-year pre-development peak flow. It is recommended that the implementation of source controls in the Chines watershed be designed on a detention basis rather than infiltration basis until a groundwater monitoring study can identify safe areas for infiltration. IV p:\ \00_ismp\engineering\03.02_conceptual_feasibility_report\phase 6\rpt_mv_masterjsmp_final_ _mm.docx

9 ATTACHMENT #2 November 16, 2015 OurFile: /000/ Doc#: V1 To: From: Subject: For: City Manager General Manager, Engineering and Public VVorks Mundy and Chines Integrated Watershed Management Plans Council Recommendation: That Council: Purpose: 1. Adopt the final report of the Mundy Creek Integrated Watershed Management Plan (IWMP) dated October 2015; 2. Receive the draft final report of the Chines Stormwater Management Plan (ISMP) dated November The purpose of this report is to seek Council's adoption of the Mundy Creek IWMP and to present the draft Chines jsmp for information. Copies of the plans are available for viewing in the Clerk's office. Strategic Goal: Development of watershed management plans support the City's goal of enhancing the sustainability of City services and infrastructure. Background: IWMP's preserve watershed health while facilitating development by investigating issues related to stormwater runoff, flood protection, watercourses, wildlife, vegetation and land use. The plans combine engineering, environmental and planning objectives to develop cost-effective and balanced solutions. IWMP's are developed by a technical staff committee representing several City departments, stakeholders and an engineering consultant team. The term Integrated Stormwater Management Plan (I5MP) is used by some other Jurisdictions. The City uses the term Integrated Watershed Management Plan (IWMP) to acknowledge the interconnected elements of a watershed which impact drainage patterns and watercourse health. File #:H /000/2015-l Doc#f; V1

10 ATTACHMENT #2 Page 2 November 16, 2015 Discussion/Analysis: Coquitlam has completed IWAAP's for eight watersheds: Stbney, Austin/Rochester, Nelson, Como, Scott/Hoy, Hyde and Partington and Mundy. The Chines ISMP is in the draft final stage and the Maple IWMP is nearing completion. Mundy Creek IWMP In September 2015, the draft report of the Mundy Creek IWMP was received by Council-in-Cbmmittee ("Integrated Watershed Management Planning - Status Update" report, Attachment l). A copy of the plan has b^eh posted on the City's website since that time. There are no significant land use changes planned within the watershed and a hydraulic analysis deemed the existing capacity of the storm system to be adequate. As such, the plan focuses on protection and enhancement of watercourses and natural habitat. The City's Rainwater Management Requirements are recommended for new develppment applications in the watershed, consistent with other IWMP's. The plan also provides baseline data for future enyirorimental mpnitpring which will track watershed health and evaluate the effectiveness Pf improvement strategies Chines ISMP The Chines ISMP is a joint study with Port Moody and Metro Vancouver that covers a collection of small watersheds flowing into the Burrard Inlet (Attachment 2). Metro Vancouver manages the trunk drainage mains and watercourses in the Chines area. The key objectives of the Chines ISMP include: pevelpping a landslide risk methodology to assess steep escarpment slopes and perform a risk analysis to identify potential hazards Managing runpffto reduce erosion activity and address any flooding risks Enhancing aquatic and terrestrial habitat including identification of long-term strategies for partial stream daylighting Providing improvements in aesthetics/livability within the watershed Managing rainwater through volume and peak flow reduction and improve water quality Performing a capacity analysis of the trunk drainage system File #: /000/ Doc#; V1

11 ATTACHMENT #2 Pages November 16,2015 The key issues in the'chines watershed are: Stability of steep ravine slopes Redevelopment in Port Moody associated with the Evergreen Line Isolated flooding caused by debris blocking intakes to the piped system at the bottom of the ravine There is potential for public access trails to be developed to cohriect neighbourhoods above and below the Chines. Currently, most trails within the study area are intended for maintenance crews only and are not suitable for public access. The desire to formalize the network of trails in the Chines is identified in the City of Coquitlam Master Trail Plan (August 2013) and is an important long-term goal requiring partnership with the City of Port Moody and Metro Vancouver. The City's Rainwater Management Requirements are recommended for new developments In the watershed, consistent with other IWMP's. However, due to the prevalence of steep slopes, the plan recommends that source controls be designed for detention until a grouhdvyafer mohitoring 5tudy can identify safe areas for infiltration. A qualitative landslide risk assessment was conducted by a professional geologist who performed onsite inspections to classify properties as low, medium or high risk. Seven properties were classified as "high risk" and received detailed risk assessments. In the context of this study, "high risk" is a comparative term used to identify those properties which have more risks than others. Risks were largely attributed to homeowner actions such as routing of drainage, placement of fill and construction of structures such as pools and retaining walls at the tops of slopes. seven properties were determined to have an acceptable factor of safety against slope failure. The key components of the watershed management strategy are summarized in the Executive Summary of the draft Chines ISMP (Attachment 3). File #: /000/ Doc #: V1

12 ATTACHMENT #2 Page 4 November 16, 2015 Financial Implications: The Mundy IWMP improvements are about $150,000. The Coquitlam portion of the Chines IWMP improvements are estimated at $2.7 million for upgrades to the piped system. Capacity upgrades will be phased with replacement of ageing infrastructure through the Asset Management Program and referred to the City's long range capital budgeting process. Conclusion: Development and implementation of IWMP's Will improve flood protection in the City while protecting natural assets and improving watershed health over time. Joz^f Dioszeg Attachments: 1. Cduhcil repdrt titled, "Integrated Watershed Management Planning, Status Update," dated August 21, Chines ISMP Study Area Attachments not included in 3. Chines ISMP Executive Summary the June 2016 Report. This report was prepared by Melony Burton, AScT, Supervisor Infrastructure Management and reviewed by Dana Soong, P.Eng., Manager Utility Programs. File#: /000/ Doc #; V1