Chris Denich, M.Sc., P.Eng Aquafor Beech Ltd TRIECA _ March 26-27 th , 2013
New Development ROW– Upper Middle Road Retrofits Public Realm– Green Glades Public Realm– Beach Boulevard Park Retrofit ROW Retrofit – Lakeview
Bioretention Unit New Development Oakville, Ontario Constructed in 2011 Facility- 1,600m 2 Accepts 4ha road drainage 25mm event
◦ Designed and constructed to address stormwater impacts to the habitat of Red-Side Dace, a fish species provincially designated as At Risk and protected under the Species at Risk Act (SARA). ◦ General reluctance to approve conventional SWM approaches: Wet ponds, wetlands and OGS for water quality ◦ Facility that can be characterized/become habitat are discouraged ◦ Thermal impacts are now a concern ◦ Disruption of baseflow, etc
Hydrogeological Study of Groundwater - Surface Water Interaction (Aquafor, 2009) Previous Geotechnical reports – 05 & 07 >8m of unsorted Sand & Gravel, overlain and confined within the Soil Stratigraphy valley slopes by 5 ‐ 10m of silty clay (Halton Till) Silty Clay till –low conductivity (10 ‐ 7 to 10 ‐ 10 m/s) Sand & Gravel unit – high conductivity (10 ‐ 5 to 10 ‐ 6 m/s) • 2 ‐ 3 orders of magnitude difference Hydraulic Conductivity • Using a sensitivity analysis, 15 mm/hr was determined using hand ‐ driven piezometers & sharp response to rainfall events and rapid drainage as baseflow ±122.5m Seasonally High Groundwater Table Elevation 0.2 ‐ 0.5m Groundwater Table Fluctuation
Bioretention Design Underdrain System Bioretention Facility Grass Filter Strip Plunge Pool Overflow Channel OGS Pre-Treatment 1. OGS (Stormceptor STC 14000) 2. Plunge Pool - 150m 2 3. Grass Filter Strip – 2.5m
Bioretention Facility Design Shredded Observation HW-Mulch Well Media D-Washed 50mm ø Native Sand & Gravel Underdrains
Can be characterized by the rain event type: Sm Small Ev Event ◦ Frequent/ ‘typical events’ – representing the majority of the annual rainfall events, typically characterized by low intensity, long duration.
Can be characterized by the rain event type: La Larg rge E Events ◦ Infrequent/ Large Events - these types of events occur infrequently but are characterized by high intensity and short duration.
Bioretention Media is the functional component of the system – critical to the long-term function of the system
Prototype 1 20.00 18.3 18 17.7 Prototype 2 18.00 16.00 Prototype 3 14.00 12.00 10.00 7.83 7.6 7.6 7.6 8.00 6.26 5.60 6.00 4.00 2.00 0.00 % Fines CEC (meq/100g) pH Hand Mixed Prototypes
20.00 18 18.00 15.6 16.00 14.00 12.00 10.00 7.83 7.7 7.6 7.5 8.00 6.00 4.00 2.00 0.00 % Fines CEC (meq/100g) pH Prototype 1 (Hand Mixed) Prototype 1 (Mechanically Mixed) Mechanically Mixed Prototypes – Mass Production
25.0 July 18, 2011 July 19, 2011 23.4 July 25, 2011 July 26, 2011 20.0 16.3 15.2 15.0 12.9 12.8 10.0 7.37 7.38 7.31 7.20 6.3 6.2 4.9 5.0 0.0 % Fines CEC (meq/100g) pH For Construction – Large Site
Infiltration Testing During Construction: 50-75mm/hr
Washed Un-washed
April 2012
June 2012
Bioretention Unit Retrofit Mississauga, ON Constructed in 2011 Facility- 11m 2 Accepts 0.03ha road & roof drainage 25mm event
Drainage Area Retrofit Area
Pilot Project - Retrofit Accept runoff from the small flat roof above the building’s front entrance as well as a portion of the parking lot area Existing Issues ◦ Iced sidewalk - Flat roof drainage flowed over sidewalk area ◦ Settlement of asphalt area at pedestrian cross-walk created nuisance ponding and icy conditions
Guelph Permeameter – In-situ infiltration testing Sub-surface soils investigation – hand auger 10 ‐ 15cm of topsoil 0.8 ‐ 1.0m of Silty, Fine sand (approx 10% silt) Soil Stratigraphy >2m of Fine sand At 1.5m depth below surface ‐ hydraulic conductivity Hydraulic Conductivity of native soils = 2.03x10 ‐ 3 cm/s or 73mm/hr No water table encountered at depths greater than Groundwater Table Elevation 2.5m throughout testing (June –August)
Inlet Grate Dry River Bed Bioretention Facility Outlet Grate Existing Electrical Trench
Existing Electrical Trench Prelim Revised liminary D sed D Desi sign Design
30.0 Approved Media Mix (Mechanically Mixed) 25.9 Refuted Sample (High) 25.0 Refuted Sample (Low) 20.0 15.6 15.2 14.8 15.0 13.4 10.0 7.7 7.6 7.5 7.5 5.0 0.0 % Fines CEC (meq/100g) pH For Construction – Small Site
Be Before re
Af After
ROW Retrofit within older residential area ◦ Bioswales & Perforated Pipe System ◦ Permeable pavement ◦ Bioretention media for filtration and infiltration Mississauga, ON Construction – Spring 2012 Accepts road & property drainage
Public R ic Resp sponse ses t s to Presente ted A Alte ternatives 10.0 Support for Rating 8.0 Environ. Project Grassed Swale 6.0 Alternative R 4.0 Vegetated Swale Alt 2.0 Ditch 0.0 Improvements Alternatives Alt
Other results (Most Important to least important) 1) Parking 2) Water Quality • No Sidewalks 3) Environmental Benefits • Cost not important 4) Prevent Flooding • Same Driveway width after 5) Integration with the Environment construction 6) Improve Conveyance • 50% want perennial plants 7) Integration with Existing • Willing to do maintenance Infrastructure 8) Aesthetics
Third St.
7. 7.2m 2m w widths pro provides a access bu but is less t is le ss than cur current Ci City S Standard (8 (8.0m) Select cted t to r reduce ce im impervio ious co cover an and al allow f for addi dditional a area f for r bi bioswales
Geotechnical investigation undertaken within the existing ROW/ditches 5 ‐ 30cm of topsoil 0.2 ‐ 1.5m of Clayey Silty Fill with some sand & gravel Soil Stratigraphy Clayey Silt Till deposits at depth At 1.0 ‐ 1.2m depth below surface ‐ design infiltration Hydraulic Conductivity rate was determined to be 5.45mm/hr (2.5 SF) – 5mm/hr used in the design Observations included generally no GW (GW observed at surface in some locations ‐ Groundwater Table Elevation attributed to water perched in the ditches and fill stratum)
Water Service Line Punctured Bell Line Damaged (BellService Onsite)
To avo avoid an an ex existing gas gas lin line, a a section o of perforated und underdrain was no notched t to a allow th the g e gas l line to to tra transect th the pi e pipe
Materials not identified in the geotechnical reports!
Re-grading of properties; Infil-development (3 homes); Abandoned and/or unmarked utilities; Sump-pump and property drainage connections; No trees;
Sacrificial Geotextile
Inlet ESC Controls
Soakaway Pit Park Redevelopment of vacant land Hamilton, ON Constructed 2011 Accepts parking lot drainage for up to 100 year storm (full infiltration) Combined and separated storm sewers – City desire to minimize flows resulting from infill developments
Seasonally high (March- April) groundwater elevation of 1.28m below the ground surface at an elevation of approximately 75.0m was determined Groundwater – Infiltration Testing Sands and Gravel Seasonally High
Groundwater – Seasonally High = Major Design Concern due to site location
Recommend
More recommend
