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© 2014 HDR Architecture, Inc., all rights reserved.© 2014 HDR Architecture, Inc., all rights reserved.© 2014 HDR Architecture, Inc., all rights reserved.© 2014 HDR, Inc., all rights reserved.© 2014 HDR, Inc., all rights reserved.© 2014 HDR, Inc., all rights reserved.© 2016 HDR, Inc., all rights reserved.
© 2016 HDR, Inc., all rights reserved.
More Than a Hole in the Ground: Makingthe Most out of Stormwater Management
2017 APWA Stormwater ManagementConference
01 Background and Process
02 Design and Integration
03 The Vision
01 Background andProcess
§ Calgary Factso Same size as NYC but just 10% the populationo 2,300 hours of sunshine a yearo Weird fact – Given a gun and horse when
leave jail
§ Project Playerso Owner & Client – Truman Developmento Planner – CivicWorkso Engineer – HDR & UrbanSystemso Municipality – City of Calgary
West District Project
§ 1st Idea – Total Infiltrationo City concerned with groundwater
contamination§ 2nd Idea – Pond with Open
Spaceo Developer instructed planner to
develop comingled open spacewith pond• All developments are required 10%
of open spaceo Planner found 4th Ward park,
reached out to HDR
Conceptual Stage
historic fourth ward park | atlanta
High-level collaboration between City and Developer prior to design phaseCalgary Development Process
Development Progression
§ Ongoing discussion about park ownershipand maintenance
§ Ensures early investment by developerdoes not go to waste.
§ Formalized submittalso Master Drainage Plan (MDP)o Staged Master Drainage Plan (SMDP)o Pond Report
§ “Final Design” during conceptual stage
Conceptual Design
02 Design and Integration
§ 500 Year Rainfall Event, 24 Hour Durationo 111.3 millimeterso 4.38 inches
§ Chicago Distribution§ Design for 100-year storm, potentially 500-
year storm
Rainfall
§ Dry Ponds, Wet Ponds & Wetlands§ Planned for prior to developmento Preliminarily Sized by City
§ Focus of algae prevention§ Water Quality improvements inherent to
design, provide 85% TSS removal
Stormwater Control
§ Wet Pondo 2.5 L/s/ha allowable unit area release rate (UARR)o Store volume discharging no higher than the UARRo 2-3 meter deep permanent poolo 1 meter minimum active storage deptho 0.3 meter freeboard (~1 foot)
§ Design Stormo 100-year design storm with emergency overflow, 500-
year with no overflowo Continuous modeling, statistical evaluation to
determine 100-year storage from 55-years of datao Most conservative volume of runoff is to be design
volume.
Wet Pond Design Criteria
§ Single Event Analysis – EPASWMMo Green-Ampt Method requestedo Design storms from City of Calgary Stormwater
Manual§ Continuous Modeling – PCSWMMo Green-Ampt Method requestedo 55-years of rainfall datao Daily Temperature Data
§ Statistical Evaluation - HYFRAN
Modeling Approach
Site Specific Hydrologic Results
§ 32.8 hectares – 81.0 acres§ 82 L/s release rate – 2.89 cfs§ 100-year Design Storm – 21,233 Cubic Meters – 17.2 ac-ft§ 100-year Statistical Evaluation – 22,400 Cubic Meters – 18.2 ac-ft§ Continuous Modeling Maximum Volume – 24,670 Cubic Meters – 20.0 ac-ft§ 500-year Design Storm Volume – 27,890 Cubic Meters – Total Volume of Pond Storage 22.6 ac-ft
Wet Pond Design
Uncontrolled Peak Flow Maximum Allowable Outflow148 cfs 2.89 cfs
§ Amphitheatre§ Splash Pad§ Lower Plaza Fountain/Skating Rink§ Restaurant§ Playgrounds§ Orchard§ Community Garden§ Lawn Space§ Preserve Native Aspen Stands
Public Outreach
03 The Vision
Wet Pond and Stormwater Park§ Approach for protecting park functionality
1. Utilized continuous modeling to determinehistorical frequencies of park inundation
2. Designed elevation of features to the 24-hourdesign storm for safety
§ Developer and City created unique goals forthe park functionality.o Perimeter Walkway – 2 Yearo Amphitheatre – 10-yearo Lower Plaza – 50-yearo 500-year does not impact adjacent building
foundations
Park, Meet Pond
west district central park | calgary
§ Utilizing subsurface infiltration toapproximately double pond discharge, inorder to meet level of service requirementsfor the park.
§ Gravelly soils, providing 2.77 m3/day/m2
infiltration rate§ 0.176 cm/s infiltration outflow (6.25 cfs)
Infiltration
§ End-of-pipe treatment - Primary§ Littoral Shelf - Secondary§ Boardwalk Wetlands - Secondary
Water Quality
§ City reviewing design§ Infiltration gallery design§ Water quality analysis§ Maintenance plan§ Final model
Status and Next Steps
Questions?Contact Information:[email protected]@hdrinc.com
