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Burton L. Johnson, P.E., Michael Baker, Jr., Inc.Brenda Gasperich, P.E., CFM, Brown & Gay Engineering, Inc.
Confessions of (Former) LID Scoffers
Scoff (v) – to mock at or treat with derision
• Maybe a bit overstated!• Actually – a healthy skepticism, due to:
o Clay soilso Large and intense rainfalls
• Similar to 2010 Houston competition• Conceived to accelerate adoption, adaptation and implementation
• Hands on learning experience• 3 categories, 20 entries
Contest Overview• 3 Categories
o Urban Redevelopment – Central Library, Arlingtono Green Roadway – South Lamar Street, Dallaso Mixed Use Development – Northern Crossing West
• Real Projects• Teams provided background information• Provide a LID based design• Compare to a conventional design
o Demonstrate economic and market benefits of LID
• Must have an engineer, landscape architect, and architect
Northern Crossing West
SITE 1
SITE 2
DETENTION/WETLAND MITIGATION
SITE 3
Primary LID Features• Reclaim rainwater for irrigation• Bio‐swales replace storm sewers• Impervious pavers in parking areas• Establishment of native prairie vegetation
Recycled Rainwater• Rainwater from rooftops collected into cisterns
• Used as primary irrigation source
• Non‐potable• However, water is cheap
o At least it is today!
Bio‐Swales/Bio‐Retention•Underdrain system• Storage AND conveyance•Underdrains convey to bio‐retention
• Bio‐Retention – larger features that provide redundancy
Pervious Pavers
Native Prairie Vegetation
100‐year Hydrograph• 55% reduction in peak 100‐year flowratefrom site
• 10% reduction in runoff volume
• Treatment of 1 ¾” of first flush runoff
Cost Comparison
Sustainable DevelopmentEdward Barbier (1987)
• Traditional Development = $7,458,595• Low Impact Concept = $6,998,400
Cost Savings of 6%
Contest Format
• Initial Submittalo 30 Page Power Pointo 1‐2 24” x 36” posterso Reviewed by expert panel
• Finals Evento Lightning presentationo Jury Panel ‐ influential development, civic, and government leaders
Takeaways• There is no reason why LID cannot work in our region
• It can be competitive, but it is not necessarily “cheaper”
• Today’s Hydrologist and engineers want to model – techniques are needed to assist in direct hydrologic calculations
• Bio‐swales and bio‐retention are tomorrow’s (or perhaps today’s) storm sewers and detention basins
• Recycling of rainwater presents a great opportunity, but as long as water costs are low it will be of less economic interest
• We are very excited about the prospects of LID – NO MORE SCOFFING!
Takeaways
San Antonio LID Competition
• Registration due March 4• www.texaslid.org