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Sea Aire Stormwater Austin Balser, Daniel Chewning, Kelly Creswell, Tyler DuBose

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1. Austin Balser, Daniel Chewning,Kelly Creswell, Tyler DuBose 2. Introduction Overview Problem Goals Constraints Literature Review Design Methodology and Materials Analysis of Information Synthesis of Design Alternative Design Options Approach to Solution and Final Design Sustainability Budget Timeline References 3. Problem Recognition: Urban and suburban development leads to high runoffrates and low infiltration rates which reduce the qualityof ground and surface water Definition: Rapid increase of development in Charleston, SCleading to high volume of runoff and flooding 4. Goal Design a stormwater management plan for Sea Airesubdivision that: Meets state regulations by ensuring the peak flowduring a 2 and 25 year storm event doesnt exceed pre-developmentlevels Ensures the post-development runoff volume doesntexceed pre-development levels 5. Robinson Design Engineers: Site Plan 6. Robinson Design Engineers: Site Plan 7. Constraints Ecological: Must work with existing soil, water table,vegetation, and waterways Ultimate use: Residential living and recreationalspace Skills: Limited knowledge and experience withstormwater design Cost: Budget of $1200 for design process. Must accountfor travel expenses, software, and testing services Additional: Difficulty working with regulators andcontractors 8. Questions of User, Client and Designer User- Residents of Sea Aire What is a rain garden, why are there plants in the ditch? What do I have to do? Client- New Leaf Builders through Robinson DesignEngineers Will this meet regulations? Will it cost more? Designer- The design team and RDE Will this be long lived? Can this be an amenity? 9. Governing Equations Energy Balance +122 + mgha = PbV +12mvb2 + mghb Mass Balance = Curve Number Method =0.2 2+0.8, =1000 10 Hortons Equation = + (0 ) Universal Soil Loss Equation T=RKLSCP 10. Stormwater Management Conventional Methods versus LID methods Conventional methods provide solutions at the bottomof the site (ponds, basins, ect.) Low impact development methods encourageinfiltration from all locations on site in an effort tomimic the more natural process 11. Comparison of Volume1 Pre-development2 Conventional Methods3 LID MethodsLID methods maintain pre-developmentrunoff volumewhile conventional methodslead to increased volume 12. Conventional Methods Detention basins Drains Concrete ditches Culverts 13. Low Impact Develop Methods Green roofs Rain water collection Constructed Wetlands Bioretention cells Rain gardens Permeable Pavements 14. Constructed Wetlands Public area of development willneed a way to catch and retainstormwater Help filter and removecontainments, Natures Kidney Shallow depression in the groundwith a level bottom 15. Design Methodology and Materials Analysis of Information Synthesis of Design Vegetative Roof Rain Barrel Rain Garden Porous Pavement Infiltration Trench Bioretention Cell Elevation of Alternative Options Stormwater Pond StormwaterWetland Selection of Final Approach 16. Analysis of Information Rainfall Distribution Data: Type II 2-year storm: 4.3 inches 25- year storm: 8.0 inches54.543.532.521.510.500 5 10 15 20 25 30Cummulative Rainfall (in)Time (hours) 17. Determining Runoff on Site Determined weighted curve number for site usingWebSoil Survey Data Calculated runoff depth using Curve Number Method Used HEC HMS and SWMM to compute and comparerunoff depth for the entire site 18. 2-Year Design Storm Hydrographs2-Year Storm: Pre- DevelopmentRunoff Depth: 0.62 inchesPeak Runoff Rate: 0.8 cfs2-Year Storm: Post- DevelopmentRunoff Depth: 2.57 inchesPeak Runoff Rate: 3.5 cfs 19. 25- Year Design Storm Hydrographs25-Year Storm: Pre- DevelopmentRunoff Depth: 2.70 inchesPeak Runoff Rate: 3.9 cfs25-Year Storm: Post- DevelopmentRunoff Depth: 5.82 inchesPeak Runoff Rate: 8.0 cfs 20. Average Residential Lot Lot Area: 4857 ft2 Roof Area: 1132.5 ft2 Driveway Area: 527 ft2 Garage Area: 264 ft2Robinson Design Engineers: Site Layout Parameters used to determine design values for LIDoptions within each residential lot. 40% of the residential lot is impervious 21. Vegetative Roof Plants Sedum Growing Media Perlite (30%) Vermiculite (20%) Crushed brick (20%) Sand (10%) Coco peat (20%) Filter fabric Drainage Layer Root Protection Layer Waterproof Membrane Structural Componenthttp://godfreyroofing.com/wp-content/uploads/2011/09/green-roofing-layers.pnghttp://www.optigreen.com/produkte/draenageplatten/fkd-40/ 22. Design Considerations Load capacity of the roof Maintenance: 2 per year Initial Growth of Vegetation Avoiding Leaks Cost of Materials Access to Roof Fire Risk Pitch of Roof Gutter Systemhttp://i.stack.imgur.com/tW8B8.jpghttp://www.jrsmith.com/uploads/fileLibrary/1010_rdp_lg.jpg 23. Vegetative Roof Holding Capacity Designed to hold 50% of the amount of water falling onthe roof during a 2-year storm Each layer of a vegetative roof has a certain water capacityComponent Water Holding Capacity TotalPlants - -Media Layer 40%, 4 inches 148.7 ft3Filter Fabric - -Drainage Layer 8 L/m2 32.3 ft3Root Protection Layer 4 L/m2 14.8 ft3Waterproof Layer - -Roof Material - - Total Water Storage: 195 ft3 24. Rain Barrels Balance between aesthetics andstorage Linked barrels increasedvolume without overwhelming size Tank Volume: 200 gallon tanks Dimensions: 47height, 36diameter To be placed on both the house andgarage Total Storage Capacity: 800gallons (4 barrels total) Overflow management:Automatic Downspout Diverterhttp://gardenwatersaver.com/connector-kits/http://gardenwatersaver.com/connector-kits/http://www.tank-depot.com 25. Automatic Downspout Diverterhttp://www.gardeners.com/buy/downspout-diverter/33-991VS.html 26. Permeable Pavementhttp://www.bae.ncsu.edu/stormwater/PublicationFiles/PermPave2008.pdf Pavement Surface Storage Underdrain 27. Design Considerations Permeable Interlocking Concrete Pavements (PICPs) Layers (SWMM) Maintenance Street sweeping Pressure washing Vacuum truck At least once per year, or after evident damage 28. PICP Design 3-inch pavement layer Mannings n = 0.019 Surface slope = 2 to 3%(less than 5%) Storage thickness = 6 to 18inches Underdrain pipe = 1 to 4inches from bottom oflayer Overall depth = 1.5 feethttp://www.bae.ncsu.edu/stormwater/PublicationFiles/ICPIreport2004.pdf 29. Bioretention Cell The public area will contain multiple bioretention cells The cells will overflow into vegetative swales orunderdrain pipes below the bioretention cell to leavethe site via the wetland/ vegetated enhanced ditchhttp://www.northinlet.sc.edu/LID/FinalDocument/loRes/4.2%20Bioretention%20low%20res.pdf 30. Can we do it?Water Storage Capacities of LID Methods If all LID methods were used together the 25 year storm could theoretically becontained on each property Due to spatial and budgetary constraints, not all LID controls will be installed ona property Therefore, management of flow into the main area from individual plots muststill be consideredDesign StormPre-DevelopmentRunoff Depth (in)Post-DevelopmentRunoff Depth (in)Increase in RunoffDepth AfterDevelopment (withno LID controls) (in)Runoff Volume (gal)2 year 0.62 3.14 2.52 762925 year 2.7 6.56 3.86 11686Green Roof (gal) Rain Barrels (gal) Infiltration Trench (gal) Permeable Pavement (gal) Rain Garden (gal) Total Water Storage (gal)1465 800 6567 1800 5520 16152 31. SWMM Modelinghttp://www.hydraulicmodel.com/sites/hydraulicmodel.com/files/images/epa_logo_1_2.thumbnail.png 32. Life Cycle Assessment Vegetative Roof: Material processing (polypropylene,HDPE, and PVC), importing of media contents Rain Garden: Native plant acquisition, capture ofCO2, pollutant decrease, aesthetic advantage Porous Pavement: Manufacturing materials (CGP,PICP, reinforced plastic pavers), transportation,reusing rock (crushed/gravel), increase water quality Infiltration Trench: 33. Life Cycle Assessment (cont.) Rain Barrel: Bioretention Cell: Material processing (PVC),transportation of sand and stone, construction Wetland/vegetated enhanced ditch: 34. Sustainability Ecological goal of zero impact on the runoff volumecoming from the site as a means of maintaining theexisting ecosystem Social ultimately serves the people living in thedevelopment. Promotes an active lifestyle and providesan educational opportunity. Economic prevents future flooding and erosion Ethical aim to balance the wishes of the clients andthe biological integrity of the site 35. Sustainability Efficiency Capture 100% of stormwater runoff on site for designstorm Carbon and Water footprint Carbon negative Gravity fed systems Plants will sequester carbon Potential for decreased freshwater demands due torainwater recycling (rain barrels) 36. Budget Vegetative Roof: $5700 not including construction costor initial roofing cost, approximately $5/ft3 See report for cost breakdown Rain Garden: Porous Pavement: approximately $3.00/sq. ft. (thisvalue depends on slope, shape) Rain Barrel: Infiltration Trench: 37. TimelineEvent 9/8 9/10 9/17 9/24 10/1 10/7 10/8 10/15 10/22 10/29 11/5 11/12 11/19 11/26 12/3Finish ProposalPresent ProposalFinish majority of Literature ReviewPick DesignStart Writing Midterm Paper3- week progress reportDevelop preliminary DesignCalculations for DesignFinish Writing Midterm paperMidterm Presentation and paper dueCost Analysis for DesignBring together final designWrite Final PaperFinal Presentation 38. Questions? 39. References http://landstudy.org/Resources.html Fangmeier, D.D., Elliot, W.J., Huffman, R.L.,Workman, S.R. 2013. Wetlands. Soil and WaterConservation Engineering. Seventh Edition. 287-302. Best Management Practices Handbook. SouthCarolina Department of Health and EnvironmentalControl.www.scdhec.gov/Environment/waterquality/stormwater/BMPHandbook/