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Evaluation of a Constructed Dry Swale for Treatment of Stormwater RunoffWilson, Laura R. January 2004 (has links) (PDF)
No description available.
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Removal of hydrocarbons from urban stormwater runoff by gravity separationBoe, Jennifer Barber 31 October 2009 (has links)
Three rain events were sampled from a storm drain at Manassas Mall in Manassas, Virginia. The urban runoff samples obtained were placed into lab-scale Plexiglas~ settling columns to monitor removal of total hydrocarbons (THC) by extended quiescent settling.
Samples were collected from the columns at specific depths and times over the 48-hour settling period. The samples were analyzed for total hydrocarbon content on a Horiba oil content analyzer. Hydrocarbon values were averaged at each column depth in order to construct average THC concentration and average THC percent removal profiles over settling time.
Maximum average THC removals were 77.8%,32.5%, and 73.6%, respectively, for Storms #1, 2, and 3 after 48 hours of quiescent settling. These average removals corresponded to depths of -2 feet, -1 foot, and -3 feet in the 5-foot tall columns.
According to traditional sedimentation theory, pollutants settle out of water to the bottom of the container of interest. This did not appear to be solely the case in this hydrocarbon sedimentation study. It appeared that sedimentation was not the sole removal mechanism at work. Some fractions of oil and grease seemed to reorganize into low-density sub-groups and float to upper regions of the column. Also, the majority of THe removal occurred within the first 18 hours of settling for two of the three storms sampled. / Master of Science
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Extended stormwater detention basin design for pollutant removalWatkins, Edwin W. 04 August 2009 (has links)
A Statistical formulation for estimating the average time of detention within a pond for a captured runoff volume is presented. It is assumed that mixing takes place during an event and that settling occurs over the period required to empty the captured volume or the time between successive events, whichever is smaller. This analytical detention time is used in conjunction with a pollutant settling efficiency-detention time curve to estimate the settling efficiency. This curve is generated from Storm Water Management Model (SWMM) simulations and shown to be independent of runoff statistics, pond configuration, and arbitrary but constant influent concentration under complete mixing. The analytical detention time estimate, in combination with the settling efficiency curve and an expression for the capture efficiency of the pond provides a valuable desktop method for the planning level design of detention basins for pollutant removal. The method performs quite well when compared to the results obtained from long-term SWMM simulation runs. / Master of Science
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Modeling urban stormwater disposal systems for their future management and designStovold, Matthew R January 2007 (has links)
[Truncated abstract]This thesis investigates aspects of urban stormwater modeling and uses a small urban catchment (NE38) located in the suburb of Nedlands in Perth, Western Australia to do so. The MUSIC (Model for Urban Stormwater Improvement Conceptualisation) model was used to calibrate catchment NE38 using measured stormwater flows and rainfall data from within the catchment. MUSIC is a conceptual model designed to model stormwater flows within urban environments and uses a rainfall-runoff model adapted to generate results at six minute time steps. Various catchment scenarios, including the use of porous asphalt as an alternative road surface, were applied to the calibrated model to identify effective working stormwater disposal systems that differ from the current system. Calibrating catchment NE38 using the MUSIC model was attempted and this involved matching modeled stormwater flows to stormwater flows measured at the catchment drainage point. This was achieved by measuring runoff contributing areas (roads) together with rainfall data measured from within the catchment and altering the seepage constant parameter for all roadside infiltration sumps. ... The MUSIC model generated future scenario outcomes for alternative stormwater disposal systems that displayed similar or improved levels of performance with respect to the current system. The following scenarios listed in increasing order of effectiveness outline future stormwater disposal systems that may be considered in future urban design. 1. 35% porous asphalt application with no sumps in 2036 2. 35% porous asphalt application with no sumps in 2064 3. 68% porous asphalt application with no sumps in 2036 4. 68% porous asphalt application with no sumps in 2064. Future scenarios using the current stormwater disposal system (with roadside infiltration sumps) with porous asphalt were also run. These scenarios reduced stormwater runoff and contaminant loading on the catchment drainage point however the inclusion of a roadside infiltration sump system may not appeal to urban designers due to the costs involved with this scenario. Climate change will affect the design of future stormwater disposal systems and thus, the design of these systems must consider a rainfall reducing future. Based on the findings of this thesis, current stormwater runoff volumes entering catchment drainage points can be reduced together with contaminant loads in urban environments that incorporate porous asphalt with a stormwater disposal design system that is exclusive of roadside infiltration sumps.
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The application of integrated environmental management to improve storm water quality and reduce marine pollution at Jeffreys Bay (South Africa) /Seebach, Rudi Dieter. January 2006 (has links)
Thesis (M. Sc. (Environmental Science))--Rhodes University, 2006.
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Urban stormwater management in VietnamLe Phu Vo. January 2000 (has links) (PDF)
Bibliography: leaves 84-91. Examines the current status of urban stormwater and water resources management in Vietnam
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The end of the pipe : integrated stormwater management and urban design in the Queen’s ditchMurdoch, Scott Philip 11 1900 (has links)
The Queen's Ditch is located three kilometers north of Comox on Vancouver Island and is
roughly 1300 hectares in size. In 1998, the watershed experienced a 1 in 200-year rain event that
flooded much of the lower watershed. The Regional District of Comox-Strathcona is responsible
for land-use planning in the watershed and initiated an investigation into the stormwater runoff
problem. This thesis is divided into two components: a planning phase to identify problems with
watershed hydrology; and a design phase to illustrate urban design that manages stormwater
runoff.
Watershed assessments were conducted at the watershed and sub-watershed scale. Watershed
assessments were descriptive and helped predict future trends in land-use change. These
assessments were not able to identify site specific problems. Sub-watershed assessment was
useful at quantifying and identifying stormwater problems. Planners should use sub-watershed
hydrological performance to guide land-use planning decisions and assess hydrological and
ecological effects of development. The planning phase provides planners with a process to
prioritize candidate areas for development, conservation, and rehabilitation.
The design phase compares urban design and stormwater performance standards of a proposed
conventional design with a sustainable design. The goal of the sustainable design was to mimic
the site's natural hydrology to help reduce off-site runoff, and to ensure adequate groundwater
recharge. Objectives of the sustainable design were to preserve natural vegetation; maintain x>£
time of concentration; reduce and disconnect impervious surfaces,, and treatment first flush
flows.
Comparisons of conventional and sustainable designs indicate that stormwater runoff and
pollution can be managed at the site level. The sustainable design provides forty-seven percent
more dwelling units and exports no stormwater. The sustainable design achieves this without an
expensive stormdrain infrastructure. Stormwater is managed at the site level using small
infiltration depressions and swales. The design works with the natural hydrological processes of
the site to generate a hydrologically sustainable design. Simulated stormwater outputs were used
to test and size infiltration ponds and to assess flooding risks. The sustainable design effectively
manages stormwater production, runoff, and pollution from storm events ranging from polluted
first flush flows to large, flood producing rainstorms.
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Towards the development of a multi-criteria decision support system for selecting stormwater best management practices.Duncan, Peter Neil. January 2001 (has links)
The aim of this dissertation was to develop a multi-criteria decision support system (MCDSS) to
allow a specified manager to select with confidence one or many of these BMPs for a particular site.
The principal design approach was a review of South African and international literature pertaining
to stormwater management techniques, in particular BMPs. This information was formulated into a
primary matrix using a rank-and-weighting method. The scores were then checked against the
literature to ensure that they were reasonable, culminating in the initial MCDSS. The MCDSS was
then provided with seven scenarios, described in the literature, and the output reviewed. Although,
the MCDSS would select appropriately when given few criteria for selection when these were
increased, inappropriate outcomes resulted. Consequently, weighting factors were assigned to each
criterion. The MCDSS was further tested using all the selection criteria and the output deemed
satisfactory. The MCDSS was then tested in a case study of the Town Bush stream catchment at
eleven sites along the river network and the results were adequate. Taking into consideration the
economic aspects of BMP implementation a need also arose for the sites to be allocated to certain
authorities depending upon ownership or responsibility. The sites were prioritised depending on
potential threat to property and lastly by the hydrological nature of the stream at each site. A
stormwater plan for the study area was also proposed. Although the MCDSS was functioning
adequately it was not without its limitations. Limitations included the use of drainage areas as a
surrogate measure for peak discharge thus, not allowing the user to design a series of BMPs or
treatment chain. A second limitation was that initially the BMPs were designed as offline systems
where stormwater is managed before entering the channel but in this study they were used as inline
systems. Hence the ultimate selection was biased towards those BMPs able to deal with large
drainage areas. Recommendations for further improvement include the development of a surrogate
measure for drainage area thus allowing the user to design a treatment chain of BMPs; testing the
MCDSS in more diverse circumstances; developing a more comprehensive set of selection criteria;
and developing a clearer priority-setting model as the one used was rather simplistic. In conclusion
the MCDSS provides the user with a useful tool where the selection and implementation of BMPs
no longer has to take place in an ad hoc manner. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001
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Local ecological knowledge of flooding in the Madison Valley neighborhood of Seattle, WashingtonMcGarry, Shawna. January 2007 (has links) (PDF)
Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen (viewed 1/23/2008). "A thesis: essay of distinction submitted in partial fulfillment of the Master of Environmental Studies, The Evergreen State College, June 2007." Includes bibliographical references (leaves 66-70).
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The artificial recharge of urban stormwater runoff in the Atlantis coastal aquiferWright, Alan January 1992 (has links)
The thesis covers the investigation of the storm water runoff and artificial recharge components of the Atlantis Water Resource Management Scheme in the Southwestern Cape. The objective of the study was to obtain an in-depth knowledge of the process of artificial recharge of urban storm water runoff, in order to identify the most efficient recharge management strategy for the Atlantis aquifer. To achieve the objective it was necessary to first study the existing knowledge on urban storm water hydrology and artificial recharge by spreading, and to create a conceptual model of what might be expected. The study area was then investigated to examine how closely the actual situation was reflected by the conceptual model, enabling recommendations to be made for the sound management of the system. The stormwater runoff component was found to differ from most urban hydrological studies as a result of its large baseflow component. The sandy nature of the catchment, small percentage area of effective impervious surface, and high groundwater table resulted in the baseflow constituting more than 40% of the total storm water runoff and accounting for over 60% of the pollution load. The "first flush" effect established as a major source of pollution in other studies, was found to be of minor significance in this study area. The overall stormwater quality (excluding the noxious industrial baseflow) was found acceptable for artificial recharge within the study area, although the baseflow from the industrial sub-catchments showed the potential for being a major source of pollution in the future. The treated wastewater used for artificial recharge prior to 1987 was found to be unacceptable for recharge purposes. The treated industrial effluent should under no circumstances be recharged up-gradient of the Witzand well field. The treated domestic effluent although of a poorer quality than the resident Witzand well field groundwater could be recharged in order to boost recharge volumes and form a buffer against further intrusion by the poor quality groundwater from the Brakkefontein area. This would however only be acceptable if strict water quality control is maintained and recharge does not take place west of the present basin. The recharge basin was found to be well situated with respect to influencing the Witzand wellfield and maintaining a groundwater buffer against poor quality groundwater flow from the northeast towards the central area of the wellfield. Unfortunately the surrounding low-lying topography and sandy retaining walls have resulted in return flow and raised groundwater-levels. The raised groundwater mound does not comply with the conceptual model and together with the sandy nature of the unsaturated zone resulted in less effective purification during infiltration. The practice of letting large portions of the basin floor dry-out during summer was shown to be beneficial and the periodic cleaning of the deeper portions of the basin essential. The artificially recharged water was found to have influenced the upper portion of the aquifer well beyond the West Coast Road. The study of groundwater quality being a good method for tracing artificially recharged water. The groundwater quality has improved as a result of artificial recharge since the removal of treated wastewater from the recharge basin. The groundwater was (ii) found to be very responsive to the slightest changes in recharge basin water quality or/and quantity. Management of the recharge basin therefore had to be very much of a compromise between qualitative and quantitative approaches. The present approach of recharging all the stormwater runoff throughout the year providing the most efficient compromise under the present conditions. The study revealed that the most efficient recharge management strategy would be the recharge of treated domestic sewage effluent in the present recharge basin and all residential storm water runoff plus industrial "storm flow" stormwater runoff in a new recharge basin located northwest of the present basin. Strict water quality control must be maintained on the water discharged into the basins and an annual wet/dry cycle implemented within the basins to boost infiltration. The entire system should continue being monitored to safe guard the groundwater resource from pollution and over exploitation.
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