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1
Karlsson, Felix. "Urban stormwater ponds: Evaluation of heavy metals and organic pollutants in stormwater and stormwater sediments". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85126.
Testo completoAbstract (sommario):
Urban runoff is generated by precipitation of rain and snowmelt on impervious surfaces. The increasing demand of urbanization causes contaminants to accumulate on roads, roofs and pathways. In turn, as runoff wash off these surfaces, contaminants such as heavy metals, particles and organic pollutants end up in the stormwater. Urban stormwater ponds improve water quality of runoff by facilitating contaminants in form of particles. To preserve the function of a stormwater pond accumulated sediment must periodically be removed.Therefore, upland disposal alternatives should be evaluated. This study examined stormwater sediment and outlet stormwater quality in seven and four ponds respectively in the vicinity of Halmstad. 7 heavy metals and 24 organic contaminants were analysed in both sediments and stormwater. Results showed metal and organic contaminant concentrations in stormwater pond discharge and sediment exceeding concentrations reported in guideline values. From the analysed heavy metals, Zn and Pb was considered the most critical contaminants. Heavier organic compounds were more frequently quantified than lighter ones, where 42 % of the analysed organic contaminants were quantified in at least one sample. Variability between inlets and outlets, between ponds and between sampling occasions was observed. The observed variability suggests that the contamination level is influenced by catchment area characteristics and activities. Significant correlation from Spearman’s rank correlation was found between the individual heavy metals (Cu, Cr, Ni, Pb and Zn), which suggest they originate from similar sources
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Pater, Susan. "Stormwater in Arizona". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2010. http://hdl.handle.net/10150/147002.
Testo completoAbstract (sommario):
40 pp.Managing stormwater is important to reduce flooding, keep people safe, maintain clean water, and to reduce soil erosion. Cities have built systems of streets, washes, channels, and stormdrains to manage stormwater and direct it to major washes. Because stormwater drains from small washes to these larger watercourses, keeping stormwater clean is also important. The next time it rains, consider how the rain affects you. Do you want to go outside and play in the raindrops and puddles? What happens to the streets in your neighborhood? Do you live near any washes that flow when it rains? Where does your stormwater go?
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Regent, Yoann. "Urban stormwater management: : Optimization of the treatment of stormwater in urban areas". Thesis, KTH, Industriell ekologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-58645.
Testo completoAbstract (sommario):
The Mulden-Rigolen system, a new urban stormwater management system implemented in Germany, has been examined in this study. The aim of this new system is to replace traditional sewer system for urban road runoff, by infiltrating the incoming water locally through a dual underground system: an active top soil layer and a deeper trench of packed gravel. For each site using this system, the characteristics of the soils in terms of pH, texture, organic matter, infiltration rate as well as Heavy Metals (Cd, Cr, Cu, Pb, Zn) and Phosphorus soil concentrations were successfully determined. The measured values for the soil characteristics were still, after an operation time of up to 15 years for some sites, globally in the range of the recommendation of the German Association for Water, Wastewater and Waste, except for organic matter in some sites, suggesting the need for a more cautious maintenance. Concerning heavy metals and phosphorus content, no alarming soil contamination was observed indicating that the studied “Mulden-Rigolen” systems were still acceptable in terms of soil pollution after several years of use, according to the Danish standards. If this system seemed to have a good flexibility and adaptability to different urban land uses, its treatment efficiency still has to be fully assessed. Indeed, only a primary evaluation of its performance war carried out through a simplistic model which brought up some questions about pollutant retention (especially in case of Zn). Further research (intact soil columns experiments, sequential extractions, on-site runoff sampling) would be necessary to fully determine how well this system works in terms of water treatment.
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Iten, Shoshana, e Julia Filling. "Stormwater Governance Commoning in Rostorp, Malmö: Practicing shared responsibility in stormwater governance". Thesis, Malmö universitet, Fakulteten för kultur och samhälle (KS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-23432.
Testo completo
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Fite-Wassilak, Alexander H. "Big boxes and stormwater". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24611.
Testo completo
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Dritschel, Amanda Marie. "The Impact of Different Stormwater Fee Types: A Case Study of Two Municipalities in Virginia". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71379.
Testo completoAbstract (sommario):
Stormwater user fees (SUFs) are an increasingly popular method of generating revenue for municipalities responsible for implementing complex stormwater regulations through the NPDES permit program. These fees can be created in a multitude of ways, including a flat fee for each parcel, charging by parcel area, charging based on a runoff factor, and many others. As a case study, eight SUFs were applied to the City of Roanoke and the Town of Blacksburg, both in Virginia, to determine the effect each SUF has on how land use type impacts the revenue composition. The City of Roanoke is larger and includes more industrial areas, but less multifamily impervious areas than Blacksburg, which translates differently in the SUFs. Residential parcels comprise the highest percentage of the revenue in all eight SUFs in Blacksburg and four in Roanoke. Open space parcels don't contain much impervious area yet account for up to 27% of the revenue. Industrial parcels comprise more of the revenue in Roanoke, averaging 11.1% compared to 4.6% in Blacksburg. A detailed digitized land cover dataset was compared to Blacksburg's land cover dataset, which resulted in maximum difference of $0.02 per parcel for residential parcel fees. Exemptions of large parcels in Roanoke, like the railroad and airport, if enacted would result in a maximum increase in fees of 15% and a shift of $7,491 of the monthly revenue to the residential parcels.Master of Science
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Padmanabhan, Aarthi. "Stormwater evaluation and site assessment : a multidisciplinary approach for stormwater Best Management Practices (BMPs)". Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1141.
Testo completo
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Kary, Daniel James. "Residential Development and Stormwater Runoff". Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/KaryD2011.pdf.
Testo completo
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Vo, Le Phu. "Urban stormwater management in Vietnam". Title page, table of contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09ENV/09envl595.pdf.
Testo completo
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Chen, Yuxiao. "Zhuji wetland city stormwater recycle /". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38297590.
Testo completoAbstract (sommario):
Thesis (M. L. A.)--University of Hong Kong, 2007.Includes special report study entitled: Water level control technology in constructed wetland. Title proper from title frame. Also available in printed format.
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Boberg, Anders. "Stormwater study Linköping City Airport". Thesis, Linköpings universitet, Medie- och Informationsteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-92840.
Testo completoAbstract (sommario):
Flygindustrin är en viktig del av Linköpings näringsliv med Saab som ett av stadens största företag och arbetsgivare. Angränsande till Saab ligger Linköping City Airport vars flygtrafik delas både av den civila och militära trafiken från Saab. 2014 behöver beläggningen för flygplatsens landningsbana bytas ut och då finns det även planer på att samtidigt bygga ut banan. Antingen genom att bara bredda banan eller att även förlänga banan med 600 meter sydost. I rapporten har förslaget med både breddning och förlängning av banan beaktats. Största skälet till att bygga ut banan är för att Linköping City Airport ska kunna ta emot större plan. Vid en ombyggnation behöver dagvattenhanteringen ses över eftersom de avvattnade ytorna kommer att bli större om banan byggs ut. I dagsläget fungerar dagvattenhanteringen dåligt och vid större regn blir det lätt översvämningar. En grundläggande lösning för hur man ska lösa dagvattenhanteringen tas upp i rapporten. Rapporten tar även upp en del problem som kvarstår att lösas. Rapporten beskriver dagvattenprojektering i allmänhet samt projekteringen för ombyggnationen av rullbanan vid Linköping City Airport. För att begränsa arbetet har endast ett förslag bearbetats i rapporten, där en breddning och förlängning av banan har studerats för att se om det är möjligt att avvattna hela banan västerut i större samlingsledningar. Ett krav vid projekteringen har varit att området inte får släppa ut mer dagvatten ut i det nuvarande systemet i västra delen av flygplatsen än vad det gör idag. Därför har volymen för ett fördröjningsmagasin dimensionerats. Rationella metoden har använts för att dimensionera ledningarna. För dimensionering av fördröjningsmagasin har hänsyn tagits till rinntiden. Resultatet av projekteringen visar att det är stora mängder dagvatten som kommer att behöva fördröjas. Resultatet av projekteringen redovisas i ett antal plan- och profilritningar som visar placering av valda brunnar och ledningarna både horisontellt och vertikalt. Resultatet av projekteringen visar att det är fullt möjligt att avleda dagvattnet från banan västerut med självfall. En nackdel med detta är att mängden dagvatten som behöver fördröjas ligger på ca 1500 kubikmeter och utrymmet att bygga ett fördröjningsmagasin väster om flygplatsen visar sig vara litet. Slutsatsen är att det krävs ytterligare projektering och att ytterligare alternativ av den horisontella utformningen av dagvattennätet bör studeras för att hitta den lösningen som är mest ekonomisk hållbar. Kostnader behöver därför beaktas i projekteringen, för den enda anledningen till att landningsbanan för Linköping City Airport kommer byggas ut 2014 är om det finns en ekonomisk rimlighet i byggnationen.The airline industry is an important part of Linköping's industry, with Saab as one of the city's largest companies and employers. Adjacent to Saab is Linkoping City Airport, which air traffic is shared by both the civilian and military traffic from Saab. In 2014 the paving for the airport runway need to be replaced and in conjunction with the renewal there are plans for an expansion of the runway. Either by just widen the lane or also extending the lane with 600 meters to the southeast. The biggest reason for Linköping City Airport to expand their runway is to accommodate larger airplanes. While renewing the runway the current stormwater system needs to revised as many parts of the runway gets flooded in heavy rain. The system also needs an upgrade to be able to handle an increase in stormwater. A fundamental solution how to solve storm water management is presented in the report. The report also addresses some problems that remain to be solved. The report describes stormwater planning in general and also the planning for the rebuilding of the runway at Linkoping City Airport. To limit the work only one suggestion is processed in the report. The suggestion with both a broadening and extension of the runway is presented to see if it is possible to drain the stormwater from the entire runway to the west. A requirement throughout the planning has been that the new system can't add more stormwater than it does today to the current system in the western part of the airport. Therefore the volume for a detention storage has been calculated. The rational method has been used for sizing the pipes. For the calculations of the detention storage flow time has been taken into account. The result of the planning indicates that there are large amounts of stormwater that will be needed to be delayed. The result is presented in a number of plan and profile drawings showing the location of selected wells and pipes in both horizontally and vertically perspective. The result of the planning also shows that it is quite possible to divert surface water to the western parts of the airport, with the help of gravity. However a disadvantage is that the amount of surface water that needs to be delayed is about 1500 cubic meters, and space to construct the detention storage is scarce. The conclusion of the work is that the project requires additional planning and multiple options for the horizontal planning of the stormwater system to find the solution that has the highest economical sustainability. Costs need to be considered in the planning, and there needs to be an economic reasonableness if the airport is going to expand in 2014.
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Chen, Yuxiao, e 陳瑜瀟. "Zhuji wetland city: stormwater recycle". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38297590.
Testo completo
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Davis, Brian M. "Contemporary Stormwater without the Green". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406252321.
Testo completo
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Wong, Yik Min. "Cost saving stormwater management system". Thesis, Wong, Yik Min (2020) Cost saving stormwater management system. Honours thesis, Murdoch University, 2020. https://researchrepository.murdoch.edu.au/id/eprint/57296/.
Testo completoAbstract (sommario):
Executive Summary
The project aims to create a cost-saving stormwater solution. The objectives are to build a dashboard for water level data and weather forecast analysis. Also, to simulate how the Climate Control Pump System, which rainwater tank in estate scale and single lot scale can affect the volume of stormwater runoff and the amount of groundwater infiltration throughout the year.
Due to technical problems with the water level sensor when installed at the Environmental Technology Centre at Murdoch University, the water level in the rainwater tank was not recorded. Hence, the rainfall data from the Bureau of Meteorology was used to build the simulation for the Climate Control Pump System, which a rainwater harvest system integrated with weather forecast, water level sensor and automated pump.
The water balance models of the simulation show that the annual stormwater runoff volumes can be reduced in both single lot scale and estate scale. It is also found out that a single lot scale is able to reduce the volume of stormwater runoff for more extended periods than estate scale.
There are very little literature and research providing data for the cost and the size of stormwater treatment systems, which is unable to calculate the expenditure saved and the percentage of the extent that the stormwater treatment can reduce. However, some research suggested that the use of rainwater tanks for stormwater retention can reduce the size and cost of stormwater systems.
Further improvement can be made on this project to gather more accurate data to compare the simulation and real-life result.
15
Tharp, Rebecca. "Ecological Stormwater Management: Analysis of design components to improve understanding and performance of stormwater retention ponds". ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/934.
Testo completoAbstract (sommario):
Stormwater runoff from developed land is a source of pollution and excessive flow to waterways. The most commonly employed practices for flow and volume control are stormwater ponds and basins (also referred to as detention and retention ponds). These structures can be effective at controlling peak discharge to water bodies by managing flow timing but are often ineffective at removing nutrients, particularly in dissolved forms. Pond morphology coupled with place-specific characteristics (like soil type and drainage area characteristics) may influence plant community composition in these water bodies. The interaction of physical, chemical, and biological elements in stormwater ponds may affect their water quality performance in more significant ways than previously understood. Floating treatment wetlands (FTW) are floating rafts of vegetation that can be constructed using a variety of materials and are an emerging technology aimed at improving the pollutant removal and temperature control functions of stormwater ponds. Previous studies with field research in subtropical and semiarid climatic regions found incremental nutrient removal improvement correlated with FTW coverage of pond surface area. However, data on their performance in cold climates is lacking from the literature.
This dissertation presents data from a three-year study examining the performance of FTW on stormwater pond treatment potential in cold climate conditions and optimal vegetation selection based on biomass production, phosphorus (P) uptake, and root architectural characteristics that enhance entrapment functionality. To put the FTW pond performance data into context, results from a survey of seven permitted stormwater ponds in Chittenden County, Vermont and the ponds' associated variability in influential internal and external dynamics are also discussed. Pond morphology, drainage area land use, soil types, and biological communities are analyzed for correlative relationships to identify design factors that affect pond performance but are not controlled factors in stormwater system permitting.
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Blecken, Godecke-Tobias. "Biofiltration technologies for stormwater quality treatment". Doctoral thesis, Luleå tekniska universitet, Arkitektur och vatten, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18090.
Testo completoAbstract (sommario):
Due to high runoff volumes and peak flows, and significant contamination with (inter alia) sediment, metals, nutrients, polycyclic aromatic hydrocarbons and salt, urban stormwater is a major cause of degradation of urban water ways. Since current urban drainage systems, which heavily rely on piped sewer networks, may not be sustainable, attempts are being made to develop and refine sustainable urban drainage solutions, notably in Water Sensitive Urban Design (WSUD) and Low Impact Development (LID) concepts. Promising systems recommended for application in both WSUD and LID are stormwater biofilters (also known as bioretention systems or rain gardens) using vegetated filter media. Besides their capacity to attenuate flows and minimise runoff volumes, stormwater biofilters have proven efficacy for enhancing effluent water quality. Furthermore, they can be aesthetically pleasingly integrated even in dense urban environments. However, there are still gaps in our knowledge of the variability of biofilters' pollutant removal performance, and the factors that affect their performance.In the studies this thesis is based upon, the effects of various ambient factors, stormwater characteristics and modifications of filter design on the removal of metals, nutrients and total suspended solids (TSS) in biofilters, and pollutant pathways through them, have been investigated. For these purposes, standard biofilters and variants equipped with a submerged zone, a carbon source and different filter materials were exposed to varying temperatures and dry periods, dosed with stormwater and snowmelt, and the inflow and outflow concentrations of the pollutants were measured.Although removal percentages were consistently high (>70%), demonstrating that biofilters can reliably treat stormwater, the results show that metal outflow concentrations may vary widely depending on the biofilter design and the ambient conditions. Prolonged drying especially impaired their removal efficiency, but variations in temperature and filter media variations had little effect on metal removal rates. The adverse effects of drying could be mitigated by using a submerged zone, and thus providing a more constant moisture regime in the filters between storm events. Combined with embedded organic matter, the submerged zone especially significantly enhances Cu removal, helping to meet outflow target concentrations. Similarly, installing a mulch layer on top of the filter provides additional sorption capacity, hence metals do not ingress far into the filter and are mainly trapped on/in the top layer by sorption processes and/or mechanical trapping associated with TSS. This leads to significant metal accumulation, which facilitates biofilter maintenance since scraping off the top layer removes high proportions of previously accumulated metals, thus delaying the need to replace the whole filter media. However, removal of accumulated pollutants from the filter media is crucial for successful long-term performance of the filters to ensure that no pollutant breakthrough occurs.Nitrogen removal was found to be more variable than metal removal, and to be adversely affected by temperature increases, leading to high nitrogen leaching in warm temperatures. Phosphorus removal rates were consistently high, since most phosphorus was particle-bound and thus trapped together with TSS. However, in initial stages phosphorus was washed out from the filter media, indicating that filter media that do not have high levels of labile phosphorus should be used to avoid high effluent concentrations. Given that most outflow concentrations were far lower than those in the stormwater, biofilters are appropriate stormwater treatment systems. Dependent on the ambient conditions, the target pollutants and the sensitivity of the recipient, adaptation of the filter design is recommended. Further work is required to investigate the winter performance and improve the reliability of nitrogen removal, which is highly variable.Dagvatten är en viktig orsak till ekologiska försämringar av urbana vattendrag p.g.a. stora avrinningsvolymer, och höga flöden samt en tillförsel av diverse föroreningar, t.ex. sediment, tungmetaller, näringsämnen, polycykliska aromatiska kolväten och salt. Dagvattenhanteringen har länge varit fokuserad enbart på att leda bort vattnet i rörledningar utan att hänsyn har tagits till retention av stora flöden eller till vattenkvalitén. På grund av dessa problem har utvecklingen av uthålliga dagvattensystem blivit allt viktigare och koncept som Lokalt Omhändertagande av Dagvatten (LOD), Water Sensitive Urban Design (WSUD) och Low Impact Development (LID) har utvecklats. En uthållig lösning inom dessa koncept är dagvattenbiofiltrering.Dagvattenbiofilter är infiltrationsbäddar med växter där dagvattnet infiltrerar och renas av växterna och filtermaterialet. De har en god förmåga att fördröja stora flöden samt att reducera föroreningar i dagvattnet innan det släpps ut till recipienten. Dessutom är det en estetisk och naturnära teknik som mycket väl kan integreras arkitektoniskt i både nya och befintliga stadsmiljöer. Dock saknas det fortfarande mycket kunskap om de processer som styr reningsförmågan samt hur de påverkas av varierande omgivningsförhållanden. I denna avhandling har därför effekterna av olika omgivningsfaktorer, dagvattenegenskaper och design av biofilter på reningen av metaller, näringsämnen och sediment undersökts. För att undersöka detta har biofilter, som delvis försetts med olika filtermaterial eller en vattenmättad zon, till dels kombinerad med en kolkälla, och utsatts för olika temperaturer och torra perioder. Biofiltren har bevattnats med dagvatten eller smältvatten. Prover har tagits på ingående och utgående vatten och föroreningskoncentrationerna har analyserats. Trots att reduktionsförmågan av metaller var hög (>70%), vilket bekräftar att biofiltren har förmågan att effektivt rena dagvattnet, visar resultaten att de utgående metallkoncentrationerna kan variera mycket beroende på utformningen av biofilter och varierande omgivningsfaktorer. Torra perioder som är längre än 3 till 4 veckor minskar metallavskiljningen i biofilter, medan växlande temperaturer och olika filtermaterial hade mindre betydelse för metallreningen. Dock kan en vattenmättad zon i filtermaterialet minimera (Cu och Zn) eller till och med avlägsna (Pb) den negativa effekten av torka med avseende på reningsförmågan. I kombination med en kolkälla kan en vattenmättad zon öka reningseffekten för framför allt Cu (som inte är lika bra i standardutförande av biofilter) på grund av en ökad komplexbildning och partikulärt organiskt material. Sediment, metaller och partikelbundna dagvattenföroreningar hålls tillbaka redan i det översta filterlagret vilket leder till en hög metallackumulation. Detta underlättar filterunderhållet: genom att skrapa och ersätta bara det översta jordlagret kan en hög andel ackumulerade föroreningar tas bort från filtret. Således kan utbyte av det hela filtermaterialet fördröjas.Kvävereningen var inte lika effektiv som metallreningen. I varma temperaturer (20°C) har kväveutlakning i stället for reduktion observerats. Fosforreningen var dock hög eftersom fosfor var mestadels partikelbunden och blev därför filtrerat tillsammans med sedimentet i det översta filterlagret. I början av biofilterdriften har dock fosforurlakning från filtermaterialet observerats vilket tyder på att det inte ska innehåller höga halter av fosfor för att undvika utlakning från filtret. Eftersom de flesta föroreningskoncentrationer i det utgående vattnet var betydligt lägre än i dagvattnet är biofilter en uthållig och tillförlitlig teknik för dagvattenrening. Beroende på olika omgivningsfaktorer samt de ekologiska förhållandena i recipienten rekommenderas dock anpassning av filterdesignen. Framtida forskning behövs för att undersöka biofiltrens reningsförmåga under vinterförhållanden och för att förbättra den varierande kvävereningen.
Godkänd; 2010; 20100812 (godble); DISPUTATION Ämnesområde: VA-teknik/Sanitary Engineering Opponent: Professor Jean-Luc Bertrand-Krajewski, INSA de Lyon, Frankrike Ordförande: Professor Maria Wiklander, Luleå tekniska universitet Tid: Fredag den 8 oktober 2010, kl 10.00 Plats: F1031, Luleå tekniska universitet
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Garis, Sargon. "Sedimentation of stormwater from construction activities". Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-224318.
Testo completoAbstract (sommario):
Vattenhantering i infrastrukturprojekt är ett viktigt ämne eftersom det kan påverka den omgivande miljön på ett negativt sätt. I projekt med förorenat mark kan vattnet innehålla allt från metaller till polyaromatiska kolväten, vilket medför svårigheter att hantera. Vattenföroreningarna orsakas av utgrävning, grundläggning, injektering, betonggjutning och bergsprängning. Vattnet kan delvis bildas av regnvatten som faller på byggarbetsplatsen eller genom schaktning under grundvattennivån. Det vatten som genom pumpning avleds från en arbetsplats eller uppfodras är känt som länsvatten. Syftet med detta examensarbete är att undersöka hur urvalet och tillämpningen av metoder för länsvatten kan förenklas och optimeras för att passa svenska förhållanden. Vidare är syftet att utvärdera hur informationen om olika tekniker är relaterad till hur entreprenörer arbetar i praktiken under vissa förhållanden. Avhandlingen består av tre delar. Den första delen är en teoretisk beskrivning av svenska lagar och utsläppskrav som gäller för länsvatten, vanliga reningsmetoder som används och hantering av länsvatten i Washington. Den andra delen är en fallstudie med ett studiebesök på byggarbetsplatsen Marieholmförbindelsen. Den tredje delen består av analytiska beräkningar och jämförelser mot provdata. Resultaten visar att vanliga container behållare bör endast användas för sedimentering av sandpartiklar eftersom ytområdet är begränsat vilket ger en kortare sedimenteringstid. De har också en begränsad flödeskapacitet vilket måste tas till hänsyn för att få en effektiv sedimentering. Specifika krav på övervakning och underhåll av container behållare bör finnas för entreprenören. I fall med mindre partiklar som till exempel silt bör användning av container behållare uteslutas, förutom vid användnings som försedimenteringssteg. Resultaten visar även att vid sedimentering av partiklar mindre än medelsilt är det nödvändigt med en uppehållstid på minst 10 timmar. Uppehållstiden kan däremot skilja sig från 10 timmar till allt uppemot 100 timmar för till exempel fin silt, som har en partikelstorlek mellan 0,0063 mm-0,002 mm. För lera skulle detta innebära en uppehållstid på minst 100 timmar vilket motsvarar mer än 4 dagar. Genom att använda traditionell sedimentering som reningsteknik skulle man antingen behöva ett stort sedimentationsområde eller ett mycket lågt flöde. Detta innebär att traditionell sedimentering är orimlig att använda sig av på grund av ekonomiska aspekter, rymdbegränsningar och effektivitet. Baserad på resultat och slutsatser, föreslås följande rekommendationer: •Vanliga container behållare som kräver hög underhållning och övervakning, rekommenderas inte att användas i större utsträckning än som ett försedimenteringssteg för partiklar som är mindre än grovsilt som har en partikeldiameter mellan 0,02-0,063 mm. •Det är viktigt att ha en helhetssyn genom att skapa tydliga riktlinjer för entreprenörerna. •Det är lämpligt att använda den hydrauliska effekten, A, för att säkerställa en korrekt konfiguration och god separationskapacitet.Water management in infrastructure projects is an important topic since it could affect the surrounding environment in a negative way. In projects with contaminated land, the water could contain everything from metals to polyaromatic hydrocarbons which entails difficulties in managing. The water can be formed partly by rainwater that falls on the construction site or by excavation below the water level. The water pollution is caused by excavation, foundation, grouting, concrete castings and rock blasting. This water is known as stormwater discharges from construction activities. The aim of the thesis is to investigate how the selection and application of methods for stormwater management from construction activities can be simplified and optimized in order to suit Swedish conditions. Further the aim is to evaluate how the information available about different techniques relates to how the contractors work in practice under some conditions. The thesis consists of three parts. The first part theoretical description of Swedish laws and requirements dealing with stormwater discharge from construction activities, common purification methods that are used and management of stormwater discharge in the state Washington. The second part is a case study with a study visit at the construction site of Marieholmförbindelsen. The third part consists of analytical calculations and comparisons to measured data. The results show that regular containers should only be used to sediment sand particles since the surface area is limited which gives a reduced sedimentation time. They also have a limited flow capacity, which must be followed to work properly. The requirement of self-monitoring and maintenance for the contractor should be increased. In other cases, with smaller particles to settle such as silt, regular containers should not be used greater than as a pre-sedimentation step. The results also show that for sedimentation of particles smaller than medium silt it is necessary with a residence time of minimum 10 hours. This means that for the soil type fine silt, which has a particle range between 0.0063mm-0.002mm, the residence time can differs between 10-100 hours. For the soil type clay this would mean a residence time of at least 100 hours which equals more than 4 days. By using traditional sedimentation as purification technique one would either need a huge sedimentation area or a very small flow. Either of these solutions is unreasonable due to economic aspects, space limitations and efficiency. Based on the results and conclusions, the following recommendations can be proposed: •Regular containers demands a high maintenance and self-monitoring, and isn’t recommended to use in greater occurrence than as a pre-sedimentation step for particles smaller than course silt, which has a particle diameter between 0.02-0.063mm. •Use a holistic approach by creating clear guidelines for the contractors. •Use the hydraulic efficiency, λ, to ensure a proper configuration and a good separation capacity.
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Wall, Roland. "Ecological conditions of stormwater retention ponds". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 56 p, 2007. http://proquest.umi.com/pqdweb?did=1253509771&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Testo completo
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Sharma, Ritu. "Economic analysis of stormwater management practices". Connect to this title online, 2006. http://etd.lib.clemson.edu/documents/1175185452/.
Testo completo
20
Karlsson, Kristin. "Pathways of pollutants in stormwater systems /". Luleå : Luleå University of Technology, 2006. http://epubl.ltu.se/1402-1757/2006/05/LTU-LIC-0605-SE.pdf.
Testo completo
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Roberts, Alexandra Helen. "Sediments in urban stormwater drainage systems". Thesis, Middlesex University, 1985. http://eprints.mdx.ac.uk/13634/.
Testo completoAbstract (sommario):
Suspended sediment, transported in urban stormwater sewers, is examined in order to determine its source, size, mineralogy, form and surface texture characteristics. The transport history is studied in relation to the hydrological parameters of rainfall and discharge in one catchment. The catchment is situated in North West London where field sampling was carried out over the period from March 1980 to December 1981. A Coulter Counter is used for particle size determinations; methods of sampling and the choice of dispersant and electrolyte are discussed. Particle surface texture analysis employs Scanning Electron Microscopy and preparation methods are discussed. Elemental composition is examined by energy dispersive x-ray analysis. Particle textures are described and quantified using a detailed surface area method and the Fuzzy Technique is employed in the analysis of a large number of particles. Sediment sources in the catchment include roads, buildings, open spaces and airborne material. Sediment is washed off land surfaces during rainfall and transported along the storm sewer to the outfall. Suspended sediment sampled at the outfall is commonly in the size range 1 to 40 mm and predominantly consists of quartz particles from roads tone erosion which have undergone considerable alteration by abrasion, silica precipitation and solution during drain transport. Storms and their sediment load fall into four groups : I. Intense rainfall of short duration generates moderately high total rainfall and discharge. Sediment comprises fresh-faced, angular, particles rapidly entrained from the land surface and of unimodal size distribution. II. Long periods of rainfall of moderate intensity create high rainfall totals and moderately high discharge. Drain deposited aggregates and surface particles are transported first; silica precipitates develop later, leading to aggregation as the discharge falls: size distributions are bimodal. III. Moderate rainfall and discharge transport sediment of similar characteristics to Group II but of moderated form. IV. Low rainfall and discharge for short period transports severly altered drain sediment of bimodal size distributions. Progressive sediment alteration along the storm sewer was simulated in a flume.
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Cutbill, Linda Beverley. "Urban stormwater treatment by artificial wetlands". Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266138.
Testo completo
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Vecchio, Ann-Ariel (Ann-Ariel Nichiko). "Stormwater management and multipurpose infrastructure networks". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/73850.
Testo completoAbstract (sommario):
Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 115-132).
In urban planning and design, natural systems are a key element of explorations about how to design for sustainability. As part of these efforts, academics and practitioners have also begun to explore the ways in which the utilization of natural systems can and should change our approach to the design and function of urban areas and of infrastructure itself. As an entry point to explore the topic, this thesis focuses on stormwater management as one basic building block or fundamental component of multipurpose infrastructure development. An increasing number of cities will seek to implement green infrastructure approaches or stormwater best management practices (BMPs) in response to new regulation, desires to improve urban quality of life, and changes in attitudes about sustainability and climate change. However, a variety of urban conditions exist within and between cities, and it is therefore necessary to consider the range of possibilities for designing and implementing green infrastructure strategies in a range of built environments. At the same time, there is also the need to address other environmental, social, and cultural goals, such as creating assets from vacant land, improving the public realm, and creating connectivity through neighborhoods. This creates opportunities to develop multipurpose infrastructure projects that utilize natural systems to address multiple objectives. San Francisco, California; Lincoln, Nebraska; and Cleveland, Ohio represent three different types of urban conditions and serve as test locations to identify the factors that affect the development of multipurpose infrastructure. San Francisco has a dense urban environment, Lincoln expects continued horizontal growth through subdivisions, and Cleveland's decline in population has created a condition of vacancy throughout the city. These conditions present a range of constraints and opportunities and shape the planning, design, and implementation of multipurpose infrastructure based on stormwater management. As a result, they lead to three methods or approaches for planning and design of multipurpose infrastructure: the retrofitting city, the preemptive city, and the repurposing city. These three approaches highlight how stormwater management can serve as a basis to develop multipurpose infrastructure systems that function at a range of scales, serve multiples purposes and create additional value for communities.
by Ann-Ariel Vecchio.
M.C.P.
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Wang, Chih-Yu. "Floating wetlands for urban stormwater treatment". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/52036.
Testo completoAbstract (sommario):
A floating treatment wetland (FTW) is an ecological approach which seeks to reduce point and nonpoint source pollution by installing substrate rooted plants grown on floating mats in open waters. While relatively novel, FTW use is increasing. A review of literature identified several research gaps, including: (1) assessments of the treatment performance of FTWs; (2) evaluations of FTWs in the U.S., particularly within wet ponds that receive urban runoff; and (3) plant temporal nutrient distribution, plant growth rate, and the long-term persistence of the FTWs in temperate regions with periodic ice encasement.
An assessment model, i-FTW model, was developed, and its parameter s fitted based on data from 14 published FTW studies in the first research topic. The estimated median FTW apparent uptake velocity with 95% confidence interval were 0.048 (0.018 - 0.059) and 0.027 (0.016 - 0.040) m/day for total phosphorus (TP) and total nitrogen (TN), respectively. The i-FTW model provided a more accurate prediction in nutrient removal than two common performance metrics: removal rate (mg/m2/day) and removal efficiency (%). In the second research topic, the results of a mesocosm experiment indicated that FTWs with 61% coverage, planted with pickerelweed (Pontederia cordata L.) or softstem bulrush (Schoenoplectus tabernaemontani), significantly improved TP and TN removal efficiency of the control treatment by 8.2% and 18.2%, respectively. The pickerelweed exhibited significantly higher phosphorus and nitrogen removal than the softstem bulrush when water temperatures were greater than 25 deg C. Field observations in the third research topic found that pickerelweed demonstrated higher phosphorus removal performance (7.58 mg/plant) than softstem bulrush (1.62 mg/plant). Based on the observed seasonal changes in phosphorus distribution, harvest of above-ground vegetation is recommended to be conducted twice a year in June and September. Planted perennial macrophytes successfully adapted to stresses of the low dissolved oxygen (DO) concentrations (minimum: 1.2 mg/L), ice encasement, and relatively low nutrient concentrations in the water (median: 0.15 mg/L TP and 1.15 mg/L TN). Systematic observation of wildlife activities indicated eight classes of organisms inhabiting, foraging, breeding, nursing, or resting in the FTWs. Recommendations for FTW design and suggestions for further research are made based upon these findings.Ph. D.
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Farmerie, Sarah Mace. "Stormwater filtration properties of pervious concrete". [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0025013.
Testo completo
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Levander, Ellinor. "Dagvatten i Vegastaden : Stormwater in Vegastaden". Thesis, KTH, Centrum för hälsa och byggande, CHB, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-40903.
Testo completoAbstract (sommario):
SammanfattningDetta examensarbete är utfört på Miljö- och stadsbyggnadsförvaltningen i Haninge kommun och är en utredning om hur dagvatten i den planerade stadsdelen Vegastaden kan hanteras. Vegastaden kommer att innebära 3000 nya bostäder, en ny pendeltågsstation och en ny anslutning till väg 73. Området där Vegastaden kommer att byggas är mycket kuperat och har varierande jordkapacitet. Vissa områden har växlande infiltrationsmöjligheter och består av morän- och hällområden, andra består av täta jordlager av lera med mycket liten genomsläpplighet. Drevviken, som är recipient för dagvattnet i Vegaområdet, är i dagsläget överbelastad med dagvatten så tyngdpunkten har lagts på lokalt omhändertagande av dagvatten. Dammar, trög avledning, våtmark, gröna tak, infiltration och översilningsytor diskuteras i rapporten som även innefattar beräkningar av vattenavrinning, undersökning av infiltrations- och översilningsmöjligheter, fördröjning samt dimensionering av diken och dammar. Examensarbetet ska ge en uppfattning om hur stor del av dagvattnet som kan hanteras genom LOD (lokalt omhändertagande av dagvatten) och ge en idé om hur stora ytor som behövs för fördröjning och rening i dammar. Haninges dagvattenstrategi som antogs i kommunfullmäktige i april 2005 har påverkat utformningen av examensarbetet. Under 1999 och 2000 byggdes en kretsloppsanpassad serviceanläggning, Green Zone, i Umeå som möjligtvis kan ge inspiration till hur dagvattnet i Vegastaden kan hanteras. Samtliga byggnader utformades med gröna tak och minskar avrinningen från hustaken med 50 %. För avrinningsberäkningar och dimensionering av dammar och diken har dataprogrammet Storm Tac använts. Olika scenarier presenteras där det visas hur mycket avrinningen kan reduceras genom olika åtgärder. Då inga åtgärder vidtas beräknas avrinningen till ca 195 506 m 3/år och med rejäla åtgärder i form av gröna tak och infiltrationsytor beräknas avrinningen till 88 137 m 3/år. För att ta hand om det dagvatten som måste ledas bort på grund av att det varken avdunstar, infiltrerar eller tas upp av växter så har dammar dimensionerats. Beroende på hur stora åtgärder som vidtas för att minska avrinningen varierar dammarnas storlek mellan ca 1 800 m 2och 3 700 m 2. Infiltrationsytor bör läggas där de gör som störst nytta och gröna tak där infiltration en i marken är som sämst. Kan man inte i dagsläget bestämma till hur stor del dagvattnet ska tas omhand lokalt bör förutsättningarna för ett sådant omhändertagande i framtiden göras goda, genom att till exempel bygga taken med en lutning och konstruktion som i framtiden klarar gröna tak och minimera de hårdgjorda ytorna. Då grundvattnet står högt i området är ett dike knappast ett alternativ till bortledning av dagvatten, men däremot skulle en dagvattenkanal i betong klara av att leda bort vatten. Området kan klara sig med endast en damm vad gäller avrinning och rening och den förläggs lämpligast öster om järnvägsspåret där de lägsta punkterna finns.AbstractThis thesis was carried out at the Environment- and town planning department in the municipality of Haninge and is an inquiry of how stormwater in the planned quarter, Vegastaden, can be managed. Vegastaden will involve 3000 new dwellings, a new commuter train station and a new connection with road 73. Drevviken, which is the recipient of stormwater in the neighbourhood of Vega, is overloaded with stormwater so the focus in this thesis is on local management of stormwater. Ponds, slow off leading, wet lands, green roofs, infiltration and filter strips are discussed in the thesis which even contains calculations of water run off, investigation of infiltration- and filter strips possibilities, slow off leading and dimensioning of swales and ponds. The thesis will give an apprehension of how large volume of the stormwater that can be handled through local handling of stormwater and give an idea of how large areas that will be needed for retardation and treatments in ponds. The stormwater strategy of Haninge was accepted in the municipal council in April 2005 and has influenced the model of this thesis. The area where Vegastaden will be built is very hilly and has varying ground capacity. Some areas have varying infiltration possibilities and consists of moraine and flat rocks, other areas consists of seal earth-layers of clay with minimal permeability. During 1999 and 2000 an ecocycle society service construction, Green Zone was built in Umeå which possibly can give inspiration in how to manage the storm water in Vegastaden. All the buildings were designed with green roofs which reduce run off from the roofs with 50 %. The computer program Storm Tac has been used for run off calculations and dimensioning of ponds and swales. Different scenes are introduced where it shows how much of the run off that can be reduced through different measures. When no measures are taken the run off is calculated to ca 195 506 m 3/year and with great measures in form of green roofs and filter strips the run off is calculated to ca 88 137 m 3/year. To manage the stormwater that has to be led off on account of no evaporation or infiltration ponds have been dimensioned. Depending on the measures taken to reduce the run off, the size of the ponds will vary between ca 800 m 2and 3700 m2. Filter strips should be placed where they do the greatest good and green roofs where the infiltration in the ground is the worst. If there is no way today to decide how much of the storm water that should be managed locally the conditions for such a management in the future should be favoured through for example green roof friendly roof constructions and to minimize the non-permeable surfaces. Because of the high ground water in the area a swale is hardly a good alternative when leading off storm water, but a stormwater canal of concrete should be able to lead off stormwater. The area should manage with only one pond regarding run off and treatment and is suitably placed east of the railway where the lowest parts are.
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Armstrong, Andrea. "Organizational Adaptation in Local Stormwater Governance". DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4439.
Testo completoAbstract (sommario):
Much of the past research and policy analysis on issues of western water has focused on inter-basin river agreements, large infrastructure that captures and distributes water, and conflict between agricultural and urban water demands. My dissertation asks a set of different questions:
How is water governed and managed within communities of Utah?
How are the organizations that manage water responding to changes in population, water availability, and water quality policy?
The answers to these questions are essential for understanding the ways in which changes to water quantity and quality will be addressed in the present and coming years. To better understand the ways in which local water management organizations, including irrigation groups and municipalities, manage water in Utah, I conducted three major types of research activities. First, in 2013, I attended 18 meetings of local water management organizations and conducted 18 interviews of organization representatives that managed water within the Heber and Cache Valleys of northern Utah. In 2014, I built upon the knowledge learned in the 2013 observations and interviews, and conducted an online survey of stormwater managers throughout the state of Utah. To build upon survey responses, I then conducted 30 follow-up interviews of stormwater managers that represented municipal stormwater programs. This research was funded with a combination of support from the National Science Foundation’s iUTAH EPSCoR project (iutahepscor.org) and funds from the Utah Storm Water Advisory Committee, a group that represents municipal stormwater programs at the state level.
My findings suggest that local water management organizations are already responding to growth and expansion in urban land use, rising uncertainties in water supplies, and shifting responsibilities for stormwater governance and management toward local governments. To cope with these changes, organizations are using a combination of strategies, including working with private consultants and collaborating with one another. With increasing pressures from environmental change and added responsibilities through decentralized water policies, it is expected that these adaptive strategies will persist or even spread to other local water management organizations yet to take on these behaviors.
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Bayley, Mark. "Constructed Ponds for the Treatment of Urban Stormwater - Biotic Processes Influencing the Removal of Nitrogen, Phosphorus and Carbon". Thesis, Griffith University, 2007. http://hdl.handle.net/10072/367630.
Testo completoAbstract (sommario):
Stormwater ponds for the treatment of urban runoff are being increasingly used as ‘treatment’ technologies in the management of urban stormwater world wide. Although stormwater ponds have been proven to be effective at reducing the concentration of nutrients from urban stormwater, the exact processes leading to this reduction remains largely unknown and unquantified. With stormwater management fast becoming a managed and mitigated water quality issue, the importance of our understanding on how these ecosystem function increases. A stormwater pond system designed and built for the treatment of urban runoff in 2001 was used as the study site for the PhD investigation. The primary goal of the PhD study was to investigate and quantify biological processes leading to N, P, and C load reduction within the inlet and outlet ponds at the Bridgewater Creek Stormwater Treatment System (BWC System) in Brisbane, Southeast Queensland Australia. The BWC System consists of 6 interconnected ponds spanning a total surface area of 0.8 ha, and draining 198 ha catchment consisting almost entirely of residential, single lot development. The initial sedimentation basin (Pond 1) and the final polishing pond (Pond 6) of the BWC System were the focus of the investigation.
Based on rainfall runoff rates, 29.5% of the catchment feeding into the stormwater treatment pond system was classed as ‘directly connected impervious area’, with each storm event delivering a mean 18.3ML of urban runoff. Data showed that storm events generating greater than 9.89 mm of rainfall produced runoff volumes greater than the storage capacity of the BWC System, thus triggering the high flow bypass channel. During the study period (2003-2005), 56.9% of all generated stormwater bypassed the BWC System, attributed to the small size of the pond system compared to its catchment drainage area. Within Ponds 2-6 of the treatment system, stormwater was retained for up to 9 days. Nutrient load reduction within the pond system was calculated at 50%, and 16% for TN and DOC respectively, but TP loads increased by 30% within the pond system. The export of TP loads greater than input for the given events within the BWC System was attributed, in part, to sediment resuspension and transportation due to the lack of significant macrophyte stands to stabilize sediment within the system. Possibly a result of this, the BWC System rarely achieved TP water quality objectives, set by the Brisbane City Council, but TN, Org-N, NH4, NOx and PO4 objectives where achieved more than 40% of the time.m Using Principal Component Analysis, three factors where found to significantly influence the variability of water quality within the pond system on a temporal scale. That being, ‘storm events’, ‘phosphorus dynamics’, and/or ‘DIN dynamics’. These factors effectively describe the abiotic or biotic variables driving water quality within the ponds at any given point in time. Key physicochemical parameters driving water quality in the ponds included pH, redox potential and DO. Water quality was similar between pelagic and littoral zones of both ponds within the BWC System.
The phytoplankton community within the BWC System was characteristic of polluted freshwaters, dominated by mixotrophic green algae. Cyanobacteria blooms within the ponds was minimal, with one bloom of Anabaena spp. occurring in Apr-04. Phytoplankton production rates were indicative of eutrophic freshwater environments (0.6-20 gC m?² day?¹), with production limited by light. Bacterioplankton production far exceeded that of phytoplankton production (8-210 gC m?² day?¹) during all incubations, defining the pond system as net heterotrophic. These high rates of bacterioplankton production coupled with the phytoplankton production suggested that the mineralsation of gross particulate organic matter entering the system during stormevents may be providing the nutrients nessasary to fuel such high production rates. Within Pond 1, nutrient movement across the benthic/water column interface were calculated at 0.73, 0.37 and 0.47 mg m?² day?¹ for TN, TP and DOC. In Pond 6, there was a gross loss of nutrients from the water column to the sediment zone for TN and TP (0.24 and 0.03 mg m?² day?¹) but not for DOC (sediment to water movement, 0.17 mg m?² day?¹). As in Pond 6, if sunlight can penetrate the benthos and gross particulate matter is low, Benthic Macro Algae can inhabit the benthos and enhace nutrient loss from the water column. During the mesocosom experiments the Ceratophyllum/epiphyton complex exhausted ammonia concentrations within the incubation jars and reduced PO4-P to background concentrations. Attached epiphyton and phytoplankton community displayed similar characteristics in PO4-P concentration reduction from the water column, with biotic uptake within the incubation jars limited to 0.03 and 0.02 mg L?¹ day?¹ respectively (0.14 mg L?¹ day?¹ for Ceratophyllum/epiphyton complex). From these incubation experiments, the important role of submerged macrophyte communities in nutrient reduction from the water coloumn was proven.
The research presented in this thesis justifies the use of stormwater ponds for urban stormwater management. The ability of submerged macrophytes at enhancing nutrient removal from stormwater was demonstrated. Phytoplankton and Bacterioplankton production and associated inorganic N and P uptake within the pond system did not correspond to measured and calculated storm flow inputs, indicating a large ‘unmeasured source’ – assumed to be the input of large particulate organic matter into the system during storm events.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Full Text
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Hardin, Michael. "THE EFFECTIVENESS OF A SPECIFICALLY DESIGNED GREEN ROOF STORMWATER TREATMENT SYSTEM IRRIGATED WITH RECYCLED STORMWATER RUNOFF TO". Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3681.
Testo completoAbstract (sommario):
One of our greatest threats to surface-water quality is polluted stormwater runoff. In this research, investigated is the use of a green roof irrigated with recycled stormwater runoff to remove pollutants from stormwater runoff and reduce the volume of stormwater runoff leaving developed areas. The green roof properties of interest are the filtration and biological processes as well as the roof's ability to hold water and increase evapotranspiration, reducing the volume of stormwater runoff from the source. Because of the above mentioned reasons the experiment consists of a water quality analysis and a water budget done on several experimental chambers modeled after the green roof on the student union building at the University of Central Florida. The green roof chambers are used to study different types of growing media, different irrigation rates, and the addition of plants and how stormwater runoff quality and quantity is affected. There are also control chambers built to model the conventional roof on the student union building. The purpose of the control is to determine the effectiveness of the different media's filtration/adsorption processes and ability to hold water, in addition to identifying the benefits of adding a green roof to both water quality and the water budget. This research showed that a specifically designed green roof stormwater treatment system with a cistern is an effective way to reduce both the volume of and mass of pollutants of stormwater runoff. The year long water budget showed that this system can reduce the volume of stormwater runoff by almost 90%. The green roof model developed within this work showed similar results for the same conditions. Design curves produced by the model have also been presented for several different geographic regions in Florida. The green roof stormwater treatment system presented within this work was effective at reducing the mass of pollutants. However, the concentration of several of the examined pollutants in the effluent of the cistern was higher or equivalent to that of a control roof. Nitrate and ammonia were two that had a lower concentration than the control roof. The use of a pollution control growing media was also examined. The results of this study show that the Black & GoldTM growing media is effective at removing both ortho-phosphorus and total phosphorus. Isotherm analysis was also preformed to quantify the adsorption potential. Despite the promise of the Black & GoldTM growing media to remove phosphorus the plants did not grow as well as in the expanded clay growing media. It is suggested that the pollution control media be used as a layer under the growing media in order to get the benefits of both media.M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering
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O'Hanlon, Eoghain Rua Patrick Allen O'Hanlon. "Evaluating the Effectiveness of Stormwater Quality Improvement Devices (SQIDs) in Sub-Tropical Conditions". Thesis, Griffith University, 2012. http://hdl.handle.net/10072/366913.
Testo completoAbstract (sommario):
Stormwater quality improvement devices (SQIDs) are frequently installed to improve the water quality of runoff to match particular water quality objectives (WQOs). However, there is a lack of data to evaluate the functioning and performance of these systems, particularly in sub-tropical climates. The primary aim of this study was to collect such data. Another aim was to establish baseline monitoring of an urban catchment before the installation of SQIDs and to forecast the improvement to the water quality after installation.
This study investigates the performance of two SQIDs (a pond and wetland) within a treatment train that has been retrofitted into a sub-tropical urban catchment (Waterbird Park) on the Gold Coast, Queensland, Australia. The method used to evaluate the effectiveness of this system was through rainfall events, sampling of the inlets to the pond, its outlet and the outlet of the wetland. Sampling was conducted through the use of automatic sampling devices, before the retrofit, during the construction phase and after the construction of the treatment train. A secondary study was conducted on a separate catchment, (Discovery Park), in which no SQIDs were installed. The Discovery Park site was used as a baseline study, where the objective was to estimate the likely improvement that a lake and wetland treatment train would have at that site.Thesis (Masters)
Master of Philosophy (MPhil)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text
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Alias, Noraliani Binti. "First flush behaviour in urban residential catchments". Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63811/1/Noraliani_Alias_Thesis.pdf.
Testo completoAbstract (sommario):
The current state of knowledge in relation to first flush does not provide a clear understanding of the role of rainfall and catchment characteristics in influencing this phenomenon. This is attributed to the inconsistent findings from research studies due to the unsatisfactory selection of first flush indicators and how first flush is defined. The research study discussed in this thesis provides the outcomes of a comprehensive analysis on the influence of rainfall and catchment characteristics on first flush behaviour in residential catchments. Two sets of first flush indicators are introduced in this study. These indicators were selected such that they are representative in explaining in a systematic manner the characteristics associated with first flush.
Stormwater samples and rainfall-runoff data were collected and recorded from stormwater monitoring stations established at three urban catchments at Coomera Waters, Gold Coast, Australia. In addition, historical data were also used to support the data analysis. Three water quality parameters were analysed, namely, total suspended solids (TSS), total phosphorus (TP) and total nitrogen (TN). The data analyses were primarily undertaken using multi criteria decision making methods, PROMETHEE and GAIA. Based on the data obtained, the pollutant load distribution curve (LV) was determined for the individual rainfall events and pollutant types. Accordingly, two sets of first flush indicators were derived from the curve, namely, cumulative load wash-off for every 10% of runoff volume interval (interval first flush indicators or LV) from the beginning of the event and the actual pollutant load wash-off during a 10% increment in runoff volume (section first flush indicators or P).
First flush behaviour showed significant variation with pollutant types. TSS and TP showed consistent first flush behaviour. However, the dissolved fraction of TN showed significant differences to TSS and TP first flush while particulate TN showed similarities. Wash-off of TSS, TP and particulate TN during the first 10% of the runoff volume showed no influence from corresponding rainfall intensity. This was attributed to the wash-off of weakly adhered solids on the catchment surface referred to as "short term pollutants" or "weakly adhered solids" load. However, wash-off after 10% of the runoff volume showed dependency on the rainfall intensity. This is attributed to the wash-off of strongly adhered solids being exposed when the weakly adhered solids diminish. The wash-off process was also found to depend on rainfall depth at the end part of the event as the strongly adhered solids are loosened due to impact of rainfall in the earlier part of the event. Events with high intensity rainfall bursts after 70% of the runoff volume did not demonstrate first flush behaviour. This suggests that rainfall pattern plays a critical role in the occurrence of first flush.
Rainfall intensity (with respect to the rest of the event) that produces 10% to 20% runoff volume play an important role in defining the magnitude of the first flush. Events can demonstrate high magnitude first flush when the rainfall intensity occurring between 10% and 20% of the runoff volume is comparatively high while low rainfall intensities during this period produces low magnitude first flush. For events with first flush, the phenomenon is clearly visible up to 40% of the runoff volume. This contradicts the common definition that first flush only exists, if for example, 80% of the pollutant mass is transported in the first 30% of runoff volume.
First flush behaviour for TN is different compared to TSS and TP. Apart from rainfall characteristics, the composition and the availability of TN on the catchment also play an important role in first flush. The analysis confirmed that events with low rainfall intensity can produce high magnitude first flush for the dissolved fraction of TN, while high rainfall intensity produce low dissolved TN first flush. This is attributed to the source limiting behaviour of dissolved TN wash-off where there is high wash-off during the initial part of a rainfall event irrespective of the intensity. However, for particulate TN, the influence of rainfall intensity on first flush characteristics is similar to TSS and TP. The data analysis also confirmed that first flush can occur as high magnitude first flush, low magnitude first flush or non existence of first flush.
Investigation of the influence of catchment characteristics on first flush found that the key factors that influence the phenomenon are the location of the pollutant source, spatial distribution of the pervious and impervious surfaces in the catchment, drainage network layout and slope of the catchment. This confirms that first flush phenomenon cannot be evaluated based on a single or a limited set of parameters as a number of catchment characteristics should be taken into account. Catchments where the pollutant source is located close to the outlet, a high fraction of road surfaces, short travel time to the outlet, with steep slopes can produce high wash-off load during the first 50% of the runoff volume.
Rainfall characteristics have a comparatively dominant impact on the wash-off process compared to the catchment characteristics. In addition, the pollutant characteristics also should be taken into account in designing stormwater treatment systems due to different wash-off behaviour. Analysis outcomes confirmed that there is a high TSS load during the first 20% of the runoff volume followed by TN which can extend up to 30% of the runoff volume. In contrast, high TP load can exist during the initial and at the end part of a rainfall event. This is related to the composition of TP available for the wash-off.
32
Anantapadmanabhan, Anisha. "Paying for municipal stormwater services : a case study on drivers of stormwater user fees in three Massachusetts communities". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104996.
Testo completoAbstract (sommario):
Thesis: M.C.P., Massachusetts Institute of Technology, Department of Urban Studies and Planning, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 66-71).
Urban stormwater is a major source of pollution in U.S. water bodies. Addressing the problem of stormwater pollution at the municipal level can be expensive, from infrastructure maintenance to implementing regulatory best practices. These needs have put pressure on municipalities to look for a stable source of revenue that extends beyond general tax appropriations for public works projects. In this context, stormwater user fees have remained a hotly debated topic in local budget discussions and national forums about stormwater management. In comparison to the rest of the country, the adoption of fees in Massachusetts communities is plagued by low uptake. This thesis aims to understand the surprisingly small proliferation and early adaptation of stormwater user fees in Massachusetts by identifying the local drivers of fee adoption as an alternative to using local tax income in three communities: Chicopee, Fall River and Northampton. Through a descriptive case study approach using qualitative interviews and publicly available data, the research underscores four key drivers apparent in local fee adoption: financial pressure, local history, governance arrangements of budgets, and cost equity. Ultimately, communities face numerous tradeoffs that affect the momentum and intricacy of the fee adoption process. Lessons learned about the local drivers of stormwater user fees in these three cases are specifically applicable to the Massachusetts context, but can serve as a guide for other New England municipalities considering new fees.
by Anisha Anantapadmanabhan.
M.C.P.
33
Rohrer, Alastair R. "The viability of using the stormwater ponds on the Diep River in the Constantia Valley for stormwater harvesting". Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/24918.
Testo completoAbstract (sommario):
Harvesting stormwater to supplement water demands has attracted a growing interest in South Africa as concerns over the security of the country's water supply increase. Whilst stormwater harvesting has been shown to offer a viable alternative water resource, there are often concerns about its storage requirements due to space constraints in urban areas. Stormwater ponds offer a potential solution to these concerns. Since stormwater ponds are typically designed for the sole responsibility of attenuating the periodic peak stormwater flows that are associated with large storm events, they often remain underutilised. By introducing Real Time Control (RTC) systems to operate stormwater pond outlets, ponds could potentially be used to store stormwater. This could increase the benefits that stormwater ponds provide as well as offer a viable alternative water resource. To investigate the economic viability of harvesting stormwater from existing stormwater ponds, a case study was performed on a representative urban catchment – the Diep River subcatchment, located in Cape Town, South Africa. The catchment contains seven stormwater ponds, which could be retrofitted for harvesting purposes. Sixteen different stormwater harvesting scenarios were developed that modelled various non-potable demands in the vicinity as well as different storage and harvesting arrangements, created using RTC strategies, of the catchment's existing ponds. These scenarios were modelled using an assortment of modelling tools which include: a catchment stormwater model; water distribution network models; and a Life Cycle Cost Analysis (LCCA). The economic viability of harvesting stormwater from the Diep River subcatchment's stormwater ponds was most susceptible to the cost of the system's water distribution infrastructure. Consequently, stormwater harvesting was most economically viable if used to supply toilet, clothes washing and irrigation demands to residential properties situated in close vicinity to the system's harvesting pond as this minimised the extent of the water distribution network. The results also revealed that distributing storage amongst ponds situated throughout the catchment is an effective method of increasing the volume of stormwater a stormwater harvesting system could yield without reducing its economic viability. However, this is on the condition that the system only extracts stormwater from the most downstream pond in the catchment. Importantly, the study also revealed that the attenuation of peak flows of large storm events (up to 1-in-20 year return period), achieved when harvesting stormwater from the existing stormwater ponds would be comparable to what the ponds currently provide. The study concluded that harvesting stormwater from existing stormwater ponds is potentially viable. It also demonstrated an effective method to maximise a catchment's storage capacity using distributed storage. For stormwater harvesting to be viable however, stormwater should be used to supplement a large percentage of non-potable end-uses and requires significant uptake amongst catchment residents.
34
Giron, Efrain. "Development of a SWMM-GIS Flood Model for New Orleans Drainage Pumping Station No 4 Basin". ScholarWorks@UNO, 2005. http://scholarworks.uno.edu/td/261.
Testo completoAbstract (sommario):
An urban flood damage model for the drainage area serve by Pump Station No. 4 (Prentiss, New Orleans, Louisiana) has been completed. This study presents the research effort needed to develop a stormwater management model (SWMM) integrated with GIS that includes a Damage Model to estimate the losses produced by storm events on flood prone areas. The latest LIDAR data are used for the topography. The drainage area for this study covers approximately 3218 acres, with elevations ranging from -9 ft to 6 ft above sea level. The runoff produced is pumped into Lake Pontchartrain via London Outfall Canal. The study area includes a pump station with a capacity of 106 m3/s and a complex drainage system including a 10 ft siphon that drains the runoff on the western side. The hydrology and hydraulic routing for the watershed was estimated using the U.S. EPA Storm Water Management Model (SWMM) and the input of the model was created using a geodatabase composed of nodes, conduits and subcatchment areas developed in ArcGIS 8.2. The GIS was designed to take advantage of the importing node and graphic capabilities of the SWMM. Since all features used by SWMM were georeferenced, node flood elevation data were transferred back for display in geographic space. This approach allows for a more accurate volume computation of flooded areas by using Boolean operations on a Triangular Irregular Network (TIN) surface of node elevations and a TIN surface of LIDAR elevation data. Flood volumes were obtained for the study area by simulating a series of rain events. These flood volumes were then incorporated into a Damage model to estimate damage rating curves for the study area. The 1:100 year damage was estimated to be 17.2 million of dollars (2005 US dollars). The average annual flood damage was estimated to be 5.5 million of dollars (2005 US dollars). The developed Annual Flood Maps can be used to set rational flood insurance rates or to plan improvements to the drainage system. This information can be used by FEMA and by the private insurance industry of the State
35
Birt, Lindsay Nicole. "Evaluation of compost specifications for stormwater management". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1236.
Testo completo
36
Beck, Kade Jacob. "Design of Logan City's Stormwater Conveyance System". DigitalCommons@USU, 2017. http://digitalcommons.usu.edu/etd/6838.
Testo completoAbstract (sommario):
Logan City is located in northern Utah's Cache County. The average annual rainfall for Cache Valley is between 15 and 20 inches (PRISM 2016). Several times a year, the incomplete storm water system causes flooding, which risks industrial and agricultural lands. The current system collects storm water between 200 West and 1000 West, and discharges the water directly along 1000 West.
Cutler Reservoir, Swift Slough, and the Lower Bear River in Cache Valley do not comply with water quality regulations. The Clean Water Act of 1972 mandates that all municipal separate storm sewer systems (MS4) comply with EPA regulations, expressed as Total Maximum Daily Loads (TMDLs). Logan City's untreated storm water might contribute to the pollution in these water bodies. The pollution threatens surface water, groundwater, and wildlife in the area.
Logan City plans to implement a new wastewater treatment process. However, the new treatment process is not designed to use the existing polishing ponds. Consequently, Logan City hopes to use these polishing ponds to treat storm water.
The implementation of this design improves storm water management. 10th West Engineers (10WE) had three goals. First, design a system to transport water form the discharge locations to the holding pond. Second, design a system that provides irrigation users access to water during a storm. Third, comply with the goals of the client: design a gravity-fed system, minimize effect on wetlands, and produce an economical design.
37
Béland, Michel C. "Modelling mixing patterns in stormwater retention ponds". Thesis, University of Ottawa (Canada), 1985. http://hdl.handle.net/10393/4817.
Testo completo
38
Fryar, Colby, e Colby Fryar. "Ina Road landfill stormwater management system design". Thesis, The University of Arizona, 2006. http://hdl.handle.net/10150/626940.
Testo completoAbstract (sommario):
This report describes the design of the Ina Road Landfill Stormwater Management System. Such a system is required by the Arizona Department of Environmental Quality to efficiently and safely remove stormwater drainage from the landfill to better protect the environment and the public during storm events. Stormwater drainage systems are required at landfills to efficiently collect and remove stormwater, limit moisture that can penetrate waste, protect the integrity of the buried mass and the final cover system from washing out and reduce risk of flooding to neighboring property. The State requires that landfill stormwater management systems be designed to handle a minimum size storm event based on historical precipitation records.
39
Kadurupokune, Wanniarachchi Kankanamge Nilmini Prasadika, e s3144302@student rmit edu au. "Sustainable management of stormwater using pervious pavements". RMIT University. Civil, Environmental and Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081029.102009.
Testo completoAbstract (sommario):
Pervious pavements in car parks and driveways reduce peak discharge and the volume of runoff flowing in to urban drains and improve the water quality by trapping the sediments in the infiltrated water. This reduces the risk of pollutants such as suspended solids and particle bound chemicals such as phosphorous, nitrogen, heavy metals and oils and hydrocarbons entering receiving waters. The key objectives of the study are to establish relationships between rainfall and pervious pavement runoff and quantify improvements to infiltrated stormwater quality through the pervious pavement. The field experimental results were used to calibrate the PCSWMMPP model and to develop water flow and quality improvement transfer functions of the MUSIC model for concrete block and turf cell pavements. The research reported herein has demonstrated that pervious pavements can be introduced as a sustainable stormwater management initiative and as a key Water Sensitive Urban Design feature to deliver numerous benefits to the environment. The outcomes from the study will be useful in designing environmentally friendly car parks, pedestrian paths, light traffic drive ways, sporting grounds and public areas in the future. Land developers and local government authorities will be major beneficiaries of the study which has increased the understanding of the use of pervious pavements and explored a number of issues that previously inhibited the wider use of pervious pavements in practice.
40
Guo, Yiping. "Development of analytical probabilistic urban stormwater models". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0010/NQ41432.pdf.
Testo completo
41
Larsson, Stephan. "Can Social Learning help facilitate Stormwater Management?" Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-254133.
Testo completoAbstract (sommario):
This thesis shows the effect social learning has on various stakeholders involved in a project aimed at tackling a stormwater challenge in the city of Uppsala in Sweden and if social learning is a useful tool to address such an issue. Due to the onset of climate change societies are having to deal with increasingly complex issues. Finding sustainable answers to these challenges is proving difficult so alternative methods such innovation competitions much like the one studied in this paper are becoming attractive alternatives to conventional climate change mitigations approaches. By using an active participation method, this thesis attempts to study whether or not social learning is taking place in the innovation competition and if it is having an impact on the innovation competition. The study found that social learning is in fact taking place during the meetings which were attended but whether or not the resulting knowledge created as a result of the social learning was being used to the advantage of the stakeholders was compounded by communication issues outside of the project meetings.
42
Davies, John W. "Modelling of stormwater quality in combined sewers". Thesis, University of Westminster, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303530.
Testo completo
43
Lind, Johanna. "Stormwater modelling tools : a comparison and evaluation". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-250267.
Testo completoAbstract (sommario):
Stormwater is rain, melt and rinse water that temporarily runs off the ground surface. In cities with many impermeable surfaces large amounts of stormwater may be formed. Stormwater is diverted through conduits and ditches to recipients. If the diversion of stormwater is insufficient flooding can occur. Stormwater contains contaminants from the catchment surfaces such as nutrients, heavy metals, bacteria, organic compounds and oils. To study stormwater pollution and flows various stormwater modelling tools are used. The purpose of this thesis is to test, compare and evaluate four stormwater modelling tools and conclude their strengths and weaknesses. This was done by a literature study, a market research, definition of evaluation criteria and by testing the tools on a case study of an industrial and residential area in Scotland. The main developed evaluation criteria was model characteristics, required input, user friendliness, output and model application. The four selected tools were StormTac, Infoworks CS, SuDS Studio and MUSIC. The case study included both flow and pollutants on a yearly basis and for a rainfall event. The results from the study were compared against observed values both before and after calibration. No model gave good model predictions for all parameters. The observed volumes of water were larger than modelled for all four models even after calibration. An intercomparison between the models however gave a better fit. Regarding pollutants, the model predictions compared with observed values varied between the tools and substances. Strengths with StormTac are that it includes over 70 pollutants, includes the recipient and gave good model predictions for pollutant concentrations when compared with observed pollutants. A weakness is that StormTacs automatically calculated base flow was much smaller than observed in the case study and the tool is not suited for studies of single event rainfalls.Strengths with Infoworks CS are that it is fully distributed, a complete network is built up and the tool can be used for design of networks, flood predictions and flows over time. It is time consuming to build a model in Infoworks CS, few default pollutants are included and it gave poor model predictions for nitrogen concentrations in the case study. SuDS Studio is a unique tool for defining suitable options for retrofitting SuDS solutions and this is a strength as it is the only tool of its kind. SuDS studio gave large intervals for pollutant loads in the case study which can be difficult to interpret. A strength with MUSIC is that it is user friendly and can be used for comparing water quality pre and post treatment. It does however only include three default pollutants in the model, and only three pollutants can be modelled at a time.
44
Parsian, Habib. "In-sewer flow regulators in stormwater management". Thesis, London South Bank University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336381.
Testo completoAbstract (sommario):
The overall aim of this work is to determine the ability of several types of in-sewer flow regulator to limit and attenuate, in conjunction with some type of storage unit, the flow of stormwater into a sewer system. The intended result of these devices is the reduction of overland flooding and downstream surcharge during storm events. Various stormwater management (SWM) techniques, practised both in the UK and abroad, were reviewed with particular emphasis on attenuation and control. Several types of flow regulators were tested where the choice was based on their popularity (i.e orifice plates and vortex), and novelty (i.e self regulating valve and throttle hose). A full size laboratory rig was built to allow experimentation and comparison of in-situ performance of several flow regulators. This system was capable of generating flows of up to 100 I/s which was controlled by a pneumatic valve interfaced to a dedicated PC. The flow characteristics(discharge and upstream head) were measured efficiently and accurately by two ultrasonic sensors. Investigation of the blockage performance of the vortex flow regulators indicated that these devices retained gross solids at higher heads (i. e. after formation of vortex) which either caused increase in discharge (up to 25% for a given upstream head) or reduced the outlet area (i. e. blockages). In terms of head/discharge relationships, the SRV offered optimum performance with consistent and near constant outflow (discharge changing 3% over 1m change in head). Vortex devices exhibited a linear relationship which is attributed to small changes in the air-core diameter. Comparisons were also made on the performance of these devices in terms of outlet opening, storage and passage of gross solids. A theoretical model was developed for the vortex regulator by combining the hydraulic properties of the free vortex with Bernoulli's equation and applying the principle of maximum discharge. In this way discharge could be predicted for a vortex flow regulator with an inlet opening in terms of upstream head and geometry of the device. The model was calibrated using the laboratory data and verified against independent data sets on blocked devices and from external sources.
45
Cetin, Lauren Marie. "Evaluation of Green Stormwater Infrastructure Monitoring Protocols". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83612.
Testo completoAbstract (sommario):
Due to development of once natural landscapes, also referred to as urbanization, stormwater management has evolved in an effort to address and counteract impairment of waterways in the United States by extensively implementing best management practices (BMPs) or Green Stormwater Infrastructure (GSI). Facilities are installed without any requirement of long-term monitoring; instead relying on lab-tested or assumed pollutant removal efficiencies that often do not translate into field implementation and do not perform as intended and required by regulatory agencies. Monitoring studies have often been applied with variable standards, which lead to inconsistent results and inconclusive data. This study aims to synthesize essential components of a GSI monitoring program based on a review of existing programs (Technology Assessment Protocol – Ecology [TAPE], Technology Assessment Reciprocity Partnership [TARP], etc.). Data from past protocols was used in tandem with historic precipitation data to develop a methodology for creating a local or small region-specific protocol. This methodology was applied to the case study area of Fairfax, Virginia. Results from the study indicate that historic precipitation data and past protocol recommendations can be effectively applied in a local setting to create a more suitable protocol adapted for GSI monitoring in order to confirm designed efficiency.Master of Science
46
Siddiqi, Rubia. "Removal of Nitrates from Stormwater Using Nanoclays". DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1776.
Testo completoAbstract (sommario):
Creeks and rivers are often polluted as a result of stormwater runoff that carries various contaminants in to open water bodies, causing adverse environmental and health effects. Low impact development (LID) techniques are currently employed to treat this runoff prior to discharge. Nitrate, however, is not consistently removed by these LID techniques. This study analyzed the ability of several nanoclays to remove nitrate in runoff and determined the feasibility of using them as a soil supplement for LID implementation. Six different nanoclays and HCl-treated clays were compared (pre-modified trimethyl stearyl ammonium nanoclay, pre-modified dimethyl dialkyl amine nanoclay, unmodified hydrophilic bentonite, unmodified halloysite nanoclay, HCl modified hydrophilic bentonite and HCL modified kaolin) to the control clay, unmodified kaolin, for their ability to adsorb nitrate solution by batch adsorption experiments. The findings determined that the pre-modified trimethyl stearyl ammonium nanoclay was the most effective adsorbent, decreasing the nitrate concentration up to 86% for a nitrate to clay ratio of 6.25 mg: 1 g under normal pH (5-6) and temperature (25⁰C) conditions. The HCl acid modification did not prove to provide significant additional benefits to the clays. Column studies were also conducted on the most successful clay, pre-modified trimethyl stearyl ammonium nanoclay, to assess the breakthrough point when 0.1% w/w and 1% w/w of the nanoclay were added to Nevada Sand. The results showed a projected breakthrough pore volume of 17 when the larger fraction was added to the sand, and a corresponding hydraulic conductivity of 12.6 in/hr, which is 35% slower than the un-amended Nevada Sand. Such a high hydraulic conductivity indicated that future work can test larger fractions of clay to sand mixtures to achieve a higher number of pore volumes before the soil reaches its breakthrough point. Future studies can also further explore both batch and column experiments to assess the feasibility of implementing soil amendments to a filtration system by changing the experimental parameters, such as base soil material, types of nanoclays used, and the nanoclay to nitrate ratios. Additionally, synthetic stormwater from runoff should be used as the influent instead of a nitrate-only solution to reflect more realistic scenarios for a potential real-world application.
47
Ludwig, Andrea L. "Constructed Floodplain Wetland Effectiveness for Stormwater Management". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28460.
Testo completoAbstract (sommario):
A 0.2-hectare wetland was constructed in the floodplain of Opequon Creek in Northern Virginia as a best management practice (BMP) for stormwater management. The research goals were to 1) determine if wetland hydrology existed and quantify the role of groundwater exchange in the constructed wetland (CW) water budget, 2) estimate wetland hydraulic characteristics during overbank flows, and 3) quantify the event-scale nutrient assimilative capacity of the constructed wetland. CW water table elevations and hydraulic gradients were measured through an array of nested piezometers. During controlled flooding events, stream water was pumped from the creek and amended with nutrients and a conservative tracer in two seasons to determine hydraulic characteristics and nutrient reduction. Samples were collected at the inlet, outlet structure, and at three locations along three transects along the wetland flowpath.
Water table elevation monitoring demonstrated that wetland hydrology existed on the site. The mean residence time of the wetland was found to be 100 min for flow-rates of 4.25-5.1 m3/min. Residence time distributions of the high and low marsh features identified a considerable degree of flow dispersion. Manningâ s n varied between macrotopographic features and was significantly higher in the spring event as compared to the fall event, likely due to the presence of rigid-stem vegetation. Average wetland n was 0.62. Total suspended solid concentrations decreased with increasing residence time during both experiments. Mass reduction of pollutants were 73% total suspended solids (TSS), 54% ammonia-nitrogen (NH3-N), 16% nitrate-N (NO3-N), 16% total nitrogen (TN), 23% orthophosphate-phosphorus (PO4-P), and 37% total P (TP) in the fall, and 69% TSS, 58% NH3-N, 7% NO3-N, 22% TN, 8% PO4-P, and 25% TP in the spring. Linear regression of mass flux over the event hydrograph was used to determine pollutant removal rates between the wetland inlet and outlet. Pollutant removal rates were determined through linear regression of mass flux and were higher in the spring event than in the fall. Dissolved nitrogen species were more rapidly removed than dissolved phosphorus. TSS, TP, and TN removal were greater and faster than dissolved nutrient species, suggesting that physical settling was the dominant removal mechanism for stormwater pollutants.Ph. D.
48
DeBusk, Kathy Marie. "Stormwater Treatment by Two Retrofit Infiltration Practices". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32757.
Testo completoAbstract (sommario):
Increases in impervious surfaces associated with urbanization change stream
hydrology by increasing peak flow rates, storm-flow volumes and flood frequency, and
degrade water quality through increases in sediment, nutrient, and bacteria
concentrations. In response to water quality and quantity issues within the Stroubles
Creek watershed, the Town of Blacksburg and Virginia Tech designed and constructed
two innovative stormwater best management practices (BMPs). The goal of this project
was to evaluate the effectiveness of a bioretention cell and a CU-Structural Soilâ ¢
infiltration trench. BMP construction was completed in July 2007. Twenty-nine
precipitation events were monitored over a period of five months between October 2007
and March 2008. For each storm, inflow and outflow composite samples were collected
for each BMP and analyzed for suspended sediment, total nitrogen, total phosphorus,
fecal coliform bacteria and E-coli bacteria. The inflow and outflow concentrations and
loads, as well as total inflow and outflow volumes and peak flow rates, were then
compared to evaluate how well each BMP reduces stormwater flows, decrease peak
runoff rates and improves water quality of stormwater runoff. Results for the bioretention
cell indicate average reductions in stormwater quantity, sediment, total nitrogen, total
phosphorus and fecal coliform bacteria that exceeded 99% by mass. The CU-Structural
Soilâ ¢ infiltration trench produced reductions in stormwater quantity, total phosphorus
and sediment that averaged 60%, 45% and 51%, respectively. Preliminary bacteria
results indicated that both BMPs served as sources of E-coli, and the infiltration trench
served as a source of fecal coliform bacteria.Master of Science
49
Adams, Erica Elaine. "Operationalizing Scale in Watershed-based Stormwater Management". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/72982.
Testo completoAbstract (sommario):
Watershed-based stormwater management (WSM) has been proposed as more effective for stormwater management than traditional methods of controlling stormwater, which are carried out based on jurisdictional lines at the parcel-scale. Because WSM considers the watershed as a total unit, this method is considered to be more effective in reducing problems associated with stormwater management including environmental degradation and flooding. However, larger watersheds encompass smaller watersheds, and therefore WSM can be implemented at a wide range of scales. There has been little research on what scale is most appropriate, and more specifically, only a modest amount of work has taken stakeholder opinion into account.
The specific objectives of this study are to determine: 1) if watershed scale is an important factor in WSM, 2) whether stakeholder opinion has an effect on the appropriate scale used in WSM, and 3) what scale is most appropriate for WSM, if scale is an important factor. To meet these objectives, we delineated sub-watersheds within a watershed in southwestern Virginia, surveyed stakeholders within the watershed on their opinions of stormwater management methods, and compared the results at both watershed scales using statistical tests and decisions support software. The results of this study have important implications for geographic scale in WSM as well as the use of qualitative data in determining appropriate geographic scale in matters of implementation in the field of planning.
Master of Science
50
Hixon, Lee Franklin. "Making the Case for Tailored Stormwater Management". Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/46200.
Testo completoAbstract (sommario):
Protection of downstream channels and reduction in flooding can potentially be improved by evaluating alternative site stormwater management (SWM) strategies at a watershed scale and selecting the optimal strategy for a subject watershed. Tailoring a management strategy for a specific watershed may be worthwhile to minimize development costs and maximize downstream benefit. A hydrologic/hydraulic model for a watershed in Blacksburg, Virginia, is used to evaluate downstream results based on implementation of several alternative SWM strategies currently practiced within the United States.
Results show none of the strategies meet the goal of maintaining the baseline goal at the watershed POI for the full range of design storms. Modification to the strategy that performs best at the watershed scale did meet the watershed goal for all design storms except the 1-year. For smaller storm events, it appears that increasing the volume of an initial capture and the drawdown time to release that volume does not increase performance downstream. This is potentially significant as extra dollars spent on site would not provide extra benefit downstream. When post-development peak runoff rates are detained to the predevelopment rate for larger storm events, whether based on a site or watershed focused strategy, the watershed goal can be met. A volume reduction strategy performs well, but implementation is hindered by soils with poor infiltration and the presence of karst.
Other insight to watershed based management strategies, the role of regional facilities and predevelopment condition assumptions at the site scale to maintain a baseline condition downstream are discussed.Master of Science