Region-Wide On-Site Stormwater Management Baseline. Workshop 1 (Technical) July

Transcription

1 Region-Wide On-Site Stormwater Management Baseline Workshop 1 (Technical) July

2 Agenda Item Time Facilitator/Presenter Project Introduction, Workshop Objectives & Engagement Process 1.00pm Sean Tynan, Metro Vancouver Technical Presentation 1.10pm Laurel Morgan & David Zabil, KWL Discussion 1.30pm Sean Tynan Break 2.15pm Discussion 2.30pm Sean Tynan Workshop Recap & Next Steps 3.00pm

3 Background Metro Vancouver Establish baseline criteria for on-site rainwater management Municipalities Update bylaws (ISMP or baseline)

4 Key Stakeholders Municipal - Engineering, planning, buildings, environment - SILG, REAC, RPAC, MEMC Senior Government Private sector Non-profit

5 Process Phase 1 Confirm Baseline Summer 2014 Phase 2 Implementation & Enforcement Fall 2014 Phase 3 Reporting & Recommendations Late Early 2015

6 Process Phase 1 Confirm Baseline Summer 2014 Phase 2 Implementation & Enforcement Fall 2014 Phase 3 Reporting & Recommendations Late Early 2015 Ongoing work with SILG & Working Group Reports to REAC & RPAC as needed Workshops Workshop 1: Municipal/Technical Baseline Criteria Workshop 2: Municipal Implementation & Enforcement Workshop 3: Municipal + Private Sector Interviews (filling the gaps)

7 Workshop Objectives Technical workshop on the science 1. Introduce you to the Baseline 2. Confirm scope Quality? Single-lot? 3. Establish minimum requirement to protect watershed health & validate draft mapping approach

8 Questions on objectives, process, or legal context?

9 Technical Workshop for the Region-Wide Baseline for On-Site Rainwater Management Presentation July 30, 2014 Laurel Morgan, P.Eng.

10 Goals of the Project 10 A Baseline Standard for Rainwater Management: Action Item under the ILWRM Targeted at Single Lot Development/ Re-development Considers Residential Land Use Only Intended to Be: Basic, Minimum Standard As Simple as Possible Easy to Use/Apply July 30, 2014

11 Where Would Baseline Apply? 11 For Single Family, Duplex, Triplex Residential Only Areas and Watersheds without Integrated Stormwater Management Plans Exempt More rural or agricultural Very small areas Infill or one off developments / redevelopment Not intended for subdivision development or non-residential land uses For areas where there is no rainwater management criteria or requirement July 30, 2014

12 Main Project Elements 12 Final Draft Document Completed Define a Minimum Standard for Rainwater Management Develop Hydrologic Zones for Rainwater Management for Metro Vancouver Select BMP Solutions for Rainwater Management Baseline Develop BMP Standards Develop a Generic Draft Bylaw for Rainwater Management in Metro Vancouver Develop Supplementary Checklists and Brochures to Support Rainwater Management Implementation July 30, 2014

13 Why a Baseline? Why Manage Hydrology? 13 Region-wide Minimum Level of Rainwater Management To provide basic hydrologic management GVRD and others, Research in the 1990s and 2000s on protection of stream health Validated monitoring and modelling B-IBI indicator monitoring Correlation between impervious area and stream health July 30, 2014

14 Focus on Single Family Residential Lots 14 Missed Category for Rainwater Management Skipped or excluded from ISMPs or existing bylaws Challenging for BMP implementation Cost concerns Design and Implementation by Non- Professionals Represents a significant portion of land use in Metro Vancouver Re-development is increasing impervious cover across the region Single lot development or redevelopment Include Duplex and Triplex lots July 30, 2014

15 Metro Vancouver Land Use by Area (2006) 15 July 30, 2014

16 Developable Land Use by Area (2006) 16 July 30, 2014

17 Proposed Minimum Standard 17 Defining a Baseline for Rainwater Management Looking for a simple, across-theboard criteria Focus on volumetric capture Application to single lot development and re-development Residential land use only Achieve a C- for rainwater management Linked with development of hydrologic zones for rainwater management July 30, 2014

18 One Baseline for Metro Vancouver? 18 How Can We Work With Differences? Rainwater Management Issues Vary Steep Slopes Geotechnical Considerations Poor Soils/Bedrock Low Infiltration High Water Table No Streams Receiving Runoff Ocean/River Outfalls Rainwater Management Goals Vary How Much to Manage? What is Minimum Standard? July 30, 2014

19 Development of Baseline Criteria 19 Impact of Impervious Area on Stream Health Watershed Impervious Cover Stream Quality Potential 1 10% Sensitive 11 25% Impacted 26 % + Degraded (Non-Supporting) based on Schuler, 1994 July 30, 2014

20 Proposed Minimum Standard 20 Basis for Rainwater Management Why Do It? Protection of downstream watercourses Source of capture criteria such as: 90% of average annual rainfall 6-month, 24-hour storm What level of protection makes sense? The barely passing level of impact is at 25% impervious cover Target: Manage 75% of Runoff from Impervious Surfaces Watershed Impervious Cover Stream Quality Potential 1 10% Sensitive 11 25% Impacted 26 % + *based on Schuler, 1994 Degraded (Non- Supporting) July 30, 2014

21 A+ Criteria Versus Baseline Criteria 21 90% 75% Baseline Criterion A+ Criterion Proposed Baseline Criterion: Limit Runoff to 25% Annually Capture 40% 2-Year 24-Hour Event July 30, 2014

22 Minimum Volume Reduction Target 22 July 30, 2014

23 Proposed Minimum Standard Criteria 23 Three Hydrologic Impacts of Development Volume Criterion: Capture 40% of the 2-year, 24- hour storm rainfall depth (mm) Rate Criterion: No additional requirement for single lot residential development Water Quality: Standards are consistent, no justification for a lower standard Additional sizing criteria adds complexity Practice Standard vs. Performance Standard Practice Standard for Water Quality Paved Areas must: Be Pervious Paving OR Drain to Vegetated Areas OR Be Collected and Drained Through a Sump July 30, 2014

24 Hydrologic Zones for Rainwater Management 24 Goal: Up to Ten Zones to Help Apply Rainwater Management Considered Range of Parameters to Define Hydrologic Zones Soil suitability for infiltration Poor, Moderate, or Good Receiving water body type Creek/stream or Ocean Average annual rainfall (mm) Three zones to cover the > 1m difference between White Rock and the North Shore mountains/coquitlam Site slope Mild (< 10%) or Steep (10% +) Water table elevation High water table, or not a concern Drainage slope Lowland areas (low slopes for drainage), or other areas July 30, 2014

25 Hydrologic Zones for Rainwater Mangement 25 Proposed Parameters for Rainwater Management Zones Soil suitability for infiltration Poor (< 10 mm/hr infiltration) Good ( 10 mm/hr infiltration) Average annual rainfall Low (typical of White Rock, 1100 mm annual rainfall) Medium (typical of Surrey, 1600 mm annual rainfall) High (typical of the North Shore/Coquitlam, 2100 mm annual rainfall) Lowlands single category July 30, 2014

26 Hydrologic Zones for Rainwater Mangement 26 July 30, 2014

27 Delineation of Hydrologic Zones 27 A+ Criteria: 72% 2-year, 24-hour Rainfall Depth July 30, 2014 Proposed Baseline: 40% 2-year, 24-hour

28 Multiple Benefits of Baseline Application 28 Stream Protection and Other Benefits Water Quality Protection for Other Receiving Waters Beach Protection Water Quality of Aquatic Habitat Detention for Downstream Capacity Volume Reduction to Combined Sewers Overflow Reduction Baseflow Treatment of Dirtiest Water Climate Change Resiliency July 30, 2014

29 Identification of Zone-Specific BMPs 29 Candidate BMPs for Residential Application Start with 2012 Source Control Design Guidelines Absorbent Landscaping Rain Garden Soakaway Manhole Infiltration Trench Pervious Paving Additional BMPs Cistern i.e. Retention Tank July 30, 2014

30 Thank You! 30 Comments Welcome! Comments on the Final Draft Report and This Presentation Should be Coordinated Through Metro Vancouver. If You Have Questions After Today Please Contact: Laurel Morgan: Ph: David Zabil: Ph: Questions? July 30, 2014

31 Comparison: Natural Conditions Graph 31 July 30, 2014

32 Discussion Questions

33 Discussion Questions 1. Given location-specific issues, opportunities, and challenges, can we create a single Baseline objective for all of Metro Vancouver? 2. What is the appropriate volumetric capture needed to protect stream health? A. Percentage? B. Absolute? (e.g. 24mm/day; 1 in 2 year storm event, etc.)

34 Discussion Questions 3. What types of streams and waterways (i.e. rivers, streams, beaches, ditches, sloughs) need to be protected by the Baseline?

35 Discussion Questions 4. Water quality is not the emphasis of the Baseline. A. Should it be? B. Are there approaches to measuring water quality that can be included in the Baseline?

36 Discussion Questions 5. Today, the Baseline is intended for single-lot residential developments, such as single detached homes or duplexes. A. Is this the right approach? B. What other type(s) of development should the Baseline apply to?

37 Discussion Questions 6. Does the approach to mapping rainfall zones in the KWL report (see Figure 2.2) seem reasonable? Is it sufficiently accurate to determine BMPs? If not, how could the map be improved?

38 Next Steps 1. Online comments to August 11 th 2. Meeting summary to attendees; update Baseline - August 3. Workshop #2 (Municipal) - September 4. Workshop #3 (Municipal, Private, NGO) - October Working Group Ongoing Recruitment Phase 1 Confirm Baseline Summer 2014 Phase 2 Implementation & Enforcement Fall 2014 Phase 3 Reporting & Recommendations Late 2014/ Early 2015

39 Thank You Robert Hicks Sr. Engineer, Utility Policy & Planning Liquid Waste Services Dept. Metro Vancouver Sean Tynan Public Involvement Liquid Waste Services Dept. Metro Vancouver

40 Reference Slides

41 Baseline Objectives Protect stream & watershed health Reduce quantity Improve quality

42 Challenges Variability across region Building code Getting diverse input Engineers, planners, building inspectors, environmental managers

43 Hydrologic Zones

44 Hydrologic Zones

45 Thank You Robert Hicks Sr. Engineer, Utility Policy & Planning Liquid Waste Services Dept. Metro Vancouver Sean Tynan Public Involvement Liquid Waste Services Dept. Metro Vancouver