Urban Stormwater Management Rebecca Leonardson Rui Teles Brooke Ray Smith
Introduction Stormwater in Portugal Why urban stormwater is currently a problem What is green stormwater management? Why it is important Policy Framework for Decisionmakers Site suitability analysis Hydrologic analysis Implementation Recommendations Case Studies Bombarral downtown revitalization Vilar hillside hamlet growth
Existing Problems Flooding November 2006 River Pollution Street oil/trash runoff Sewage Discharges New Developments Bombarral More runoff Downstream impacts Vilar
Opportunity sites...
Definition: What is Green Stormwater Management? Non-mechanized stormwater collection, conveyance, detention, treatment Benefits: Reduces flood risk Reduces pollution of streams and water supply Creates habitat and enhances ecosystem function Improves landscape beauty of a town
Types and Purposes of Green Stormwater Management Rainwater collection Detention Conveyance Infiltration Treatment Re-use
Examples of Green Stormwater Management Green walls, Green roofs for water collection
Examples of Green Stormwater Management Source: www.eere.energy.gov Cisterns for water collection & storage CBF Merrill Environmental Center, Annapolis, MD Source: Landscape Architecture Cistern Detail
Examples of Green Stormwater Management Rainwater & greywater creative re-use Bombarral example here 10th at Hoyt Courtyard, Portland, OR
Examples of Green Stormwater Management Swales to channel and convey stormwater Clean Fill Clean Fill Subsurface Collection Contamination Existing Soil Parking Lot, Livermore, CA
Examples of Green Stormwater Management Source: City of Portland Planted swaled to infiltrate stormwater Source: City of Portland Swale, Cross Section
Examples of Green Stormwater Management Permeable paving for infiltration
Examples of Green Stormwater Management Constructed wetlands to reduce pollution into rivers
Examples of Green Stormwater Management Tree planters to infiltrate and treat stormwater Source: Landscape Architecture
Suitability Analysis Opportunities Underutilized areas (old buildings, vacant land) Existing pervious areas (agriculture, parks) Flood-prone areas (low elevation, in floodway) Constraints Built-out urban core (no infiltration) Steep slopes (no detention/treatment)?
Suitability Analysis: Bombarral Aerial
Suitability Analysis Topo map, slope map here
Suitability Analysis: Bombarral Flood Areas
Suitability Analysis: Bombarral Underutilized Areas
Suitability Analysis: Bombarral Green / Permeable Areas
Bombarral Case Study: Sewer & Stormwater Network
Bombarral Case Study: Sewer & Stormwater Outfall Locations
Bombarral Case Study: Treatment Opportun- ities
Bombarral Case Study: Treatment Opportun- ities
Bombarral Case Study: Stormwater & Wastewater Treatment Opportun- ities
Stormwater Treatment: Detention & Infiltration Typology Drainage Area: 305,000 m2 Peak Flow (1yr 1hr storm): 0.4 cms Stormwater runoff volume (20yr 24hr storm): 11,721 m3 Existing Basin Size (at 0.45m depth): 1,300 m2 (could detain 100% if 2m deep)
Wastewater Treatment: Bank Setback Typology
Wastewater Treatment: Urban Typologies
Policy Analysis Potential Funding Sources Developer fees - Developer incentives lower taxes Policy Strategies Performance measures for new development
Case Study: Bombarral Urban Design Strategy (diagram & calculations) Future Development Strategy (diagram & calculations) Outfall Area Treatment Strategy
Case Study: Vilar Urban Design Strategy (diagram & calculations) Future Development Strategy (diagram & calculations)
Conclusions
Stormwater Strategies Location Bombarral Vilar Existing Stormwater Challenges Flooding - sewer backflow Future Development & Retrofitting Urban runoff water quality Flooding - over AdO pipe capacity Urban runoff water quality Solution Strategies Rainwater reuse (permanent removal): cisterns Reduce peak flow (temporary removal): detention/treatment basins, swales Best Management Practices (BMPs): green roofs, cisterns, swales, performance measures Treatment wetlands Stormwater BMPs: infiltration basins, planted gutters/swales, cisterns Treatment wetlands, infiltration basins
Types and Purposes of Green Stormwater Management Type Detention Rainwater collection / Greywater re-use Conveyance Infiltration Treatment Purpose Reduce peak flow into system Reduce municipal water use Reduce volume into system Reduce peak flow into system Improve water quality Reduce volume into system Improve water quality Improve water quality Reduce peak flow into system
Backflow prevention http://www.valveandequipment.com/catalog/images/tf2.gif
Drainage standards for new development (from Seattle) Reduce impervious surfaces to 50% overall Control the 3 yr., and 25 yr, 24 hour storm Retain existing vegetation Protect river by matching the pre development hydrograph Collect, disperse and retain the roof runoff No directly connected impervious areas (either use pervious paving or bioretention)