Barrhaven Light Rail Transit and Rail Grade
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Barrhaven Light Rail Transit (Baseline Station to Barrhaven Town Centre) and Rail Grade- Separations Planning & Environmental Assessment Study Public Consultation Group Meeting #3 08 September 2020 Confidential 1 Agenda • Introductions • Study Objectives • Preliminary Recommended Plan – Baseline Station to Nepean Sportsplex – Nepean Sportsplex to Barrhaven Centre • Next Steps • Discussion Confidential 2 Study Objectives • Study commenced September 2018 • Develop Recommended Plan for: – LRT alignment and stations – SW Transitway, Woodroffe, Fallowfield rail grade- separations – Train Storage and Servicing Facility (TSSF) – Supporting Facilities • Environmental Assessment following Ontario’s Transit Project Assessment Process (TPAP) Confidential 3 Study in 2 Parts • Baseline Station to Nepean Sportsplex: – Identify preferred LRT alignment • Nepean Sportsplex to Barrhaven Centre: – Convert existing at-grade BRT Transitway to LRT – New rail grade-separations at VIA Rail crossings Confidential 4 Baseline Station to Nepean Sportsplex Confidential 5 Overview • 2.4 km long corridor • 2 km protected corridor west of Woodroffe ROW • 3 new stations Confidential 6 Three Key Design Considerations • Grade-separation and associated clearance requirements • Geotechnical conditions of concern • Limited available right-of-way in the “pinch point” Confidential 7 Grade Separation • Extension of the City’s O-Train Line: – Fully grade-separated facility designed to the same operational and safety requirements • Close spacing between street crossings and need to go over or under CN Rail line – Allowable slope and required clearance dictate vertical alignment choice needs to be consistent for entire 2.4 km segment (no mix and match) Confidential 8 Geotechnical Conditions of Concern • Recent investigations – Woodroffe and Fallowfield Grade Separations (2002, 2003) – SW Transitway Extension – Baseline to Norice (2008, 2009) – Woodroffe Watermain replacement (2014) – This EA Study (2018) • Ground conditions: – Topsoil over Sensitive Marine Clays – Up to 13 m thick, over – Sands, Silts and Glacial Till – Up to 17 m thick, over – Bedrock – depth varies from 10 to 25 m over Study Area Confidential 9 Geotechnical Conditions of Concern • These ground conditions common in the Ottawa area • Well understood by geotechnical specialists to be very challenging to address – Groundwater levels would be several meters above any the base of any below-grade alternative – All below-grade alternatives extend into permeable sands below the sensitive marine clay level – Below-grade alternatives need to be designed to prevent any lowering of groundwater as this would lead to dewatering of the clay – Dewatering of clay is likely to cause settlement of the clay and the homes and structures it is supporting – This could extend several hundred metres either side of the LRT alignment Confidential 10 Extent of Geotechnical Risks with Trench Option • Number of buildings within potential impact zone (250 m from LRT alignment): – Commercial - 18 – Institutional - 13 – Office - 10 – Residential - 647 • Roads • Underground Utilities Confidential 1111 Right-of-Way in Pinch Point • 1997 EA Plan located Transitway extension through pinch point in a cut-and-cover tunnel underneath SB lanes of Woodroffe Avenue • ROW limited to less than 40 m Confidential 12 Right-of-Way in “Pinch Point” • Approved 1997 EA plan through the “Pinch Point” to be re- evaluated • Both below-grade and elevated alternatives would be considered • Results of this focused evaluation would determine the preferred alternative for the entire Baseline Station to Nepean Sportsplex section Woodroffe Avenue facing South at Pinch Point Confidential 13 Alternatives Considered • Six alternatives between Knoxdale and West Hunt Club evaluated – Bored tunnel options screened out due to geotechnical considerations and cost – East side options screened out due to geometric design challenges, construction disruption and utility conflicts Confidential 14 Alternatives 1 and 2: Below-grade in Woodroffe Avenue ROW • Cut-and-cover tunnel or open trench Confidential 15 Alternatives 3 and 4: Elevated in Woodroffe Avenue ROW • Elevated to reduce construction challenges • Median and west-side alternatives • Median option has potential to provide a new station at Nepean Sportsplex on the east side of Woodroffe Confidential 16 Alternatives 5 and 6: West of Woodroffe Avenue ROW • Open trench and elevated alternatives • Continuous straight track geometry • Impacts some residential properties Confidential 17 Evaluation Criteria • A comprehensive list of criteria that respond to all aspects of the environment was used to evaluate the six (6) alternatives. Criteria groups included: – Transportation System Sustainability – NCC Greenbelt Sustainability – Ecological and Physical Sustainability – Land Use and Community Sustainability – Economic Sustainability Confidential 18 Findings – Elevated vs. Below-grade • Below-grade alternatives: – expose the City to more risk and liability associated with geotechnical conditions – are more expensive and challenging to construct – have reduced noise, privacy and view impacts but creates barrier – generally supported by the community (tunnel preferred) • Elevated alternatives: – reduce risk and liability associated with geotechnical conditions – are more cost-effective and easier to construct – have the potential for use of the at-grade space below the guideway for mobility or community uses Confidential 19 Preferred Alternative: Elevated West of Woodroffe Avenue Confidential 20 Evaluation Rationale (Elevated versus Trench) Geotechnical Risks • Trench options must be within continuous permanently water-tight structure to prevent leaks • Leaks could lead to lowering of water table resulting in settlement of surrounding structures and underground utilities • Leaks very difficult to repair or correct – potentially require ongoing pumping/ recharge to prevent settlement • Legal liability for possible damages Confidential 21 Below-grade Construction Methodology 2.4 Km of Continuous Watertight Wall 1 2 34 Confidential 22 Elevated Construction Methodology O/H Structure Supported on Piers every 30 – 40 m 1 2 34 Confidential 23 Evaluation Rationale (Elevated versus Trench) Minimizing Underground Utility Conflicts Confidential 24 Evaluation Rationale (Elevated versus Trench) Underground Utility Conflicts • Elevated alignment avoids conflicts with existing underground utilities that cross the corridor, thus do not require complicated solutions to maintain existing or provide new crossings. • Major impacted utilities* include: – 2100mm dia. Tallwood Storm Collector Sewer – 2250mm dia. Lynwood Sanitary Collector Sewer – 1800mm dia. Sovereign Storm Collector Sewer – 1350mm & 1200mm dia. West Hunt Club Storm Collector Sewers – Proposed Enbridge Gas Distribution Main & others • Geotechnical conditions add challenges to utility relocations and connections due to depth of watertight cut-off wall *Note: only sewers > 1000mm dia. listed, there are many more utilities that cross the corridor Confidential 25 Preferred Alternative Why Elevated? • Avoids geotechnical risks • Minimizes underground utility conflicts • Simpler and faster to build • Lower cost • Completely covering trench not a viable option Ottawa, Hurdman Station Confidential 26 Preferred Alternative Why Elevated? • Does not create community barrier that limits pedestrians and cyclist movement across corridor • Trench option requires additional crossing structures • Open space below guideway can be programmed for community benefit • Provides opportunity for new N- S MUP within corridor Confidential 27 Preferred Alternative Why West of Woodroffe Avenue? • Avoids impact to Woodroffe Avenue during and post construction • Straight alignment reduces noise, maintenance costs and provides best ride quality • Allows optimization of station locations and potential for integrated development opportunities • Best enables continuous MUP connection from Baseline Station to south of Hunt Club Road Confidential 28 Impacts to Existing Residential Properties • Three properties 1 between Knoxdale and West Hunt Club affected • 120 of 205 existing 1 dwellings directly impacted 2 • Majority of the buildings 2 constructed prior to 3 1965 (55+ year old) 3 Confidential 29 Redevelopment Potential (Concept) Confidential 30 Tallwood Station Looking Southwest Confidential 31 Knoxdale Station Looking Southeast Confidential 32 Nepean Sportsplex Station Looking Southwest Confidential 33 Public Feedback – What We Heard • Support advancing LRT and rail overpasses sooner • Elevated facility: – Noise and visual concerns – How would snow be managed? – What would space underneath be used for? • Avoid traffic impacts to Woodroffe Avenue during and post-construction • Groundwater quality impacts Confidential 34 Responses / Mitigation • Noise and vibration: no source mitigation needed • Views/Privacy: – alignment not close to existing dwellings – new developments designed to mitigate impacts • Seasonal Maintenance: snow management design guidelines such as wider guideway; MUP location • Corridor landscaping and space programming opportunities being developed • West of Woodroffe ROW avoids traffic impacts • No impact to groundwater anticipated Confidential 35 Nepean Sportsplex to Barrhaven Centre Confidential 36 Overview • Convert 7.6 km existing Transitway to twin-track electric Light Rail Transit • Includes modifying Fallowfield, Longfields, Strandherd Stations • New LRT/BRT transfer terminal station