Charleston midterm

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<p>Stormwater</p> <p>Sea Aire StormwaterAustin Balser, Daniel Chewning, Kelly Creswell, Tyler DuBoseIntroductionOverviewProblemGoalsConstraintsLiterature ReviewDesign Methodology and MaterialsAnalysis of InformationSynthesis of DesignAlternative Design OptionsApproach to Solution and Final DesignSustainabilityBudgetTimelineReferencesProblemRecognition: Urban and suburban development leads to high runoff rates and low infiltration rates which reduce the quality of ground and surface waterDefinition: Rapid increase of development in Charleston, SC leading to high volume of runoff and flooding</p> <p> a stormwater management plan for Sea Aire subdivision that:Meets state and local regulations by ensuring the peak flow during a 2 and 25 year storm event doesnt exceed pre-development levelsEnsures the post-development runoff volume doesnt exceed pre-development levelsaustin4Robinson Design Engineers: Site Plan</p> <p>Robinson Design Engineers: Site PlanConstraints Ecological: Must work with existing soil, water table, vegetation, and waterwaysUltimate use: Residential living and recreational spaceSkills: Limited knowledge and experience with stormwater design Cost: Budget of $1200 for design process. Must account for travel expenses, software, and testing services</p> <p>Kelly7Questions of User, Client and DesignerUser- Residents of Sea AireWhat is a rain garden, why are there plants in the ditch?What do I have to do?Client- New Leaf Builders through Robinson Design EngineersWill this meet regulations?Will it cost more?Designer- The design team and RDEWill this be long lived?Can this be an amenity?Governing EquationsEnergy Balance</p> <p>Mass Balance</p> <p>Curve Number Method</p> <p>Hortons Equation</p> <p>Universal Soil Loss Equation</p> <p>Daniel9Stormwater ManagementConventional Methods versus LID methodsConventional methods provide solutions at the bottom of the site (ponds, basins, ect.)Low impact development methods encourage infiltration from all locations on site in an effort to mimic the more natural processKelly10Comparison of Volume 1 Pre-development 2 Conventional Methods3 LID Methods</p> <p>LID methods maintain pre-development runoff volume while conventional methods lead to increased volume</p> <p> MethodsDetention basinsDrainsConcrete ditchesCulverts</p> <p> Impact Development MethodsGreen roofsRain water collectionConstructed wetlandsBioretention cellsRain gardensPermeable pavement </p> <p> WetlandsPublic area of development will need a way to catch and retain stormwaterHelp filter and remove containments, Natures Kidney Shallow depression in the ground with a level bottom</p> <p> Methodology and MaterialsAnalysis of InformationSynthesis of DesignEvaluation of AlternativesLID Techniques Stormwater PondStormwater WetlandSelection of Final ApproachAnalysis of InformationRainfall Distribution Data: Type II2-year storm: 4.3 inches25- year storm: 8.0 inches</p> <p>Determining Site RunoffDetermined weighted curve number for site using WebSoil Survey DataCalculated runoff depth using Curve Number MethodUsed HEC HMS and SWMM to compute and compare runoff depth for the entire site</p> <p> Storm Hydrographs</p> <p>2-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 cfs25- Year Storm Hydrographs</p> <p>25-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 cfsChange in RunoffOverall change for site2: +2.0825: +2.71Change per lot2: +2.5225: +3.86Volume retained for site2: 40833 ft3 (0.3 mil. gal)25: 67892 ft3 (0.5 mil. gal)Volume retained per lot2: 1024 ft3 (7666 gal)25: 1570 ft3 (11743 gal)Design OptionsDetention Basin125717 ft3 (0.94 million gal)0.9 Acres (15%)Treatment Wetland138288 ft3 (1 million gal)1 Acre (17%)LID Techniques1860 ft2 lot area (50%)1133 ft2 roof areaEvaluation of OptionsDetention BasinLow costSpaceTreatment WetlandHigher costSpaceLID TechniquesLower costLower spaceFinal Approach LID TechniquesVegetative RoofRain BarrelRain GardenPorous PavementInfiltration TrenchBioretention CellConstructed WetlandAverage Residential LotLot Area: 4857 ft2Roof Area: 1133 ft2Driveway Area: 527 ft2Garage Area: 264 ft240% of the residential lot is impervious </p> <p>Robinson Design Engineers: Site LayoutVegetative RoofPlantsSedumGrowing Media Filter fabricDrainage LayerRoot Protection LayerWaterproof MembraneStructural Component</p> <p></p> <p> Design ConsiderationsInitial Growth of VegetationAvoiding LeaksCost of MaterialsAccess to Roof- MaintenancePitch of RoofGutter System</p> <p> </p> <p> 26Vegetative Roof Holding CapacityDesigned to hold 50% of the amount of water falling on the roof during a 2-year stormEach layer of a vegetative roof has a certain water capacity</p> <p>Total Water Storage: 195 ft3</p> <p>Rain BarrelsBalance between aesthetics and storage 1800 gallons roof runoff (2 yr.storm)2700 gallons roof runoff (25 yr. storm)Linked barrels increased volume without overwhelming sizeTank Volume: 200 gallon tanks Dimensions: 47height, 36 diameterTo be placed on both the house and garageTotal Storage Capacity: 800 gallons (4 barrels total)Overflow management: Automatic Downspout Diverter </p> <p></p> <p>Automatic Downspout Diverter</p> <p> Pavement</p> <p> UnderdrainDesign ConsiderationsPermeable Interlocking Concrete Pavements (PICPs)Maintenance Street sweepingPressure washingVacuum truckAt least once per year, or after evident damage</p> <p>PICP Design3-inch pavement layerSurface slope = 2 to 3%Storage thickness = 6 to 18 inchesUnderdrain pipe = 1 to 4 inches from bottom of layer</p> <p> TrenchUnderground water storage and infiltration featureCoarse gravel surrounded by filter fabric and topped with soil</p> <p>Schueler, Controlling Urban RunoffDesign DetailsAppropriate area and volume15% of the lot area2196 ft3Water storage40% void space878 ft3Infiltration rate</p> <p> GardenSurface Area: 600 ft2 Soil Media 70% sand contentDepth: 3 ft. (Infiltration rate x 24 hr)Ponding Depth: 6 in.Plants: Beautyberry, Palmetto Dwarf, Purple ConeflowerWater Table Level</p> <p></p> <p>Bioretention CellsBioretention cells in public areaThe cells will overflow into vegetative swales or underdrain pipes below the bioretention cell to leave the site via the constructed wetland Constructed WetlandManage water flowing onto the site through existing ditchTreat water for quality and quantity before it leaves the siteHandle excess runoff from individual lots and common areas</p> <p> We Do It?If all LID methods were used together the 25 year storm could theoretically be contained on each propertyDue to spatial and budgetary constraints, not all LID controls will be installed on a propertyBalance between space allotment, water capacity, and budgetTherefore, management of flow into the main area from individual plots must still be considered</p> <p>SWMM Model</p> <p></p> <p>EPA SWMM, Tyler DuboseSWMM Cont.</p> <p>EPA SWMM, Tyler DuboseSustainability MeasuresLife Cycle Assessment (LCA)Materials selectedCarbon and Water costsEfficiencySocietal IssuesOverall Carbon and Water footprint Life Cycle AssessmentVegetative Roof: Polypropylene, HDPE, PVC, media transportation Rain Garden and Bioretention Cell:PVC, material transportation, construction Porous Pavement:PICP, gravelInfiltration Trench:Geotex filter fabric, gravel, excavation and transportationRain Barrel: Polyethylene Constructed Wetland:Plants, soil media, drain materials </p> <p>LCA Cont.Ecological goal of zero impact on the runoff volume coming from the site as a means of maintaining the existing ecosystem Social ultimately serves the people living in the development. Promotes an active lifestyle and provides an educational opportunity. Economic prevents future flooding and erosion Ethical aim to balance the wishes of the clients and the biological integrity of the siteDaniel43SustainabilityEfficiencyCapture 100% of stormwater runoff on site for design stormCarbon and Water footprintCarbon negative Gravity fed systemsPlants will sequester carbonPotential for decreased freshwater demands due to rainwater recycling (rain barrels)Daniel44BudgetVegetative Roof$5700 not including construction cost or initial roofing cost, approximately $5/ft3Rain Garden:$2300, not including installation costsPorous Pavement:$3450, not including installation costsRain Barrels:$1170 for all 4Infiltration Trench:$1800 gravel and geotex</p> <p>Timeline</p> <p>Questions?</p> <p>Robinson Design EngineersReferences, D.D., Elliot, W.J., Huffman, R.L., Workman, S.R. 2013. Wetlands. Soil and Water Conservation Engineering. Seventh Edition. 287-302.Best Management Practices Handbook. South Carolina Department of Health and Environmental Control.</p>