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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of a SWMM-GIS Flood Model for New Orleans Drainage Pumping Station No 4 Basin

Giron, Efrain 20 May 2005 (has links)
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
2

The Impact of Different Stormwater Fee Types: A Case Study of Two Municipalities in Virginia

Dritschel, Amanda Marie 20 June 2016 (has links)
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
3

Assessment of the Viability of a Natural Urban Wetland in the Treatment of Stormwater

McGuigan, Janeen 19 July 2013 (has links)
Stormwater runoff generated from urban areas can be a source of contamination and may negatively impact receiving waters. Best management practices, including the use of treatment wetlands, are recommended to minimize impacts and maintain the quality of water bodies receiving stormwater discharge. This study focuses on the viability of a natural wetland in the treatment of urban runoff. Kuhn Marsh is a natural urban wetland located in Dartmouth, NS. The wetland is approximately 2 ha in size and the primary inlet is a stormwater outfall servicing a 28 ha urban drainage area. Kuhn Marsh has been receiving stormwater generated from the urban drainage area for decades. A wetland drainage area of approximately 9 ha contributes to surface runoff downstream of the wetland inlet. Project objectives are defined as: (i) characterization of the hydrology and hydraulics of the wetland system, (ii) characterization of contaminant fluxes within the wetland system, and (iii) analysis of the treatment performance of Kuhn Marsh. Research strategies used to achieve project objectives include physical and hydrologic characterization of the wetland and contributing watersheds as well as surface and ground water quality analysis. Monitoring was conducted in the wetland during both baseflow and stormflow conditions from May 2011 through October 2012, with the exception of November 2011 to January 2012. Surface water samples were analyzed in the laboratory for TSS, TOC, TN, TP, turbidity, E.coli, and a suite of heavy metals including Fe, Pb, Cu, Cd and Zn. In-situ surface water monitoring included DO, temperature, conductivity and pH. Groundwater samples were analyzed for E.coli and microbial source tracking was performed on all well samples in addition to samples from the inlet and outlet of the wetland. Results from the well samples and the wetland outlet were inconclusive, however the wetland inlet showed human source bacteria indicating potential sewer cross connections within the stormwater system. It was determined that the wetland is an area of groundwater discharge, with groundwater accounting for an average of 50% of the volume discharging through the outlet control structure. Largely due to groundwater influence, Kuhn Marsh shows no peak flow dampening or volume reduction between inlet and outlet. Minimal hydraulic retention times, between 2 and 4 hours, were calculated during stormflow conditions, indicating potential short circuiting of flows through the wetland. Wetland treatment performance was analyzed on a concentration and mass reduction basis and on the number samples that exceeded parameter guidelines at the outlet of the wetland. Guideline exceedances were reported for the majority of samples taken and increases in concentration between inlet and outlet resulted in a larger number of samples exceeding guidelines at the outlet. Despite dilution from groundwater discharge, minimal to no concentration reduction was reported between the inlet and outlet of the wetland. Mass reduction did not occur between the inlet and outlet and Kuhn Marsh was found to be a source of all contaminants sampled. Results of this study show that Kuhn Marsh is no longer acting as a reservoir for stormwater contaminants and, based on the fact that the wetland has been receiving stormwater input on the order of decades, study results may be indicative of the long-term treatment capacity of a stormwater treatment wetland. In the future, comprehensive sampling of groundwater is recommended to determine if contaminants are entering the wetland via groundwater discharge, and if possible, surface water sampling should be conducted on a finer scale to better estimate mass fluxes and contaminant loading rates.
4

Design and Development of a Stormwater Policy Decision-Making Tool

Sigman, Stephanie Joy 11 December 2015 (has links)
Municipalities tend to develop their stormwater management policy by examining those of their neighboring communities, chosen out of convenience and perception of similarity rather than a purposeful, directed search. Alternatively, having a policy that is backed by science creates regulations that policy makers can confidently support. To address this issue, the model used in this study incorporates local rainfall and development data to analyze stormwater runoff volumes for various storm events using one year of development data from Chattanooga, Tennessee. The runoff values are used to analyze several policy combinations based on simplified policies, model policies, and customizable policies. Outputs of the tool include project count, impervious area managed, runoff managed, and runoff cleaned. This study indicates that stormwater managers can use the outputs of this tool to choose the policy that best meets their city’s unique goals.
5

Retrofit of an existing flood control facility to improve pollutant removal in an urban watershed

Gilpin, Amy Christine 11 September 2014 (has links)
Levels of bacteria in excess of water quality standards for contact recreational designated use have been documented in Gilleland Creek, located in northeast Travis County, Texas. Stormwater monitoring showed increased bacteria levels after rainfall runoff events in Gilleland Creek, and analysis indicates the bacteria is of a nonpoint source origin. The objective of this research was to modify a flood control basin in an urban area in the upper part of the Gilleland Creek watershed to determine whether it is possible to substantially increase bacteria removal by retaining stormwater in the basin for 24 hours after a storm event. Bacteria reduction was predicted as a result of sedimentation and exposure to sunlight. The outlet of one flood control basin was retrofitted with an automated gate valve to control stormwater outflow and acted as the test basin. Another flood control basin, located approximately ¼ mile from the test basin, was unmodified and acted as the control basin. Stormwater monitoring at the inlet and outlet to both basins over the course of five storm events showed that neither the control nor the test basin exhibited a decrease in E. coli concentrations. Both basins were effective in decreasing the concentration of total suspended solids and showed varying performance for the treatment of nutrients. The dataset is limited by the small number of storm events that were sampled, and continued stormwater monitoring would offer additional insight into retrofit performance. / text
6

Leaching Test with Sawdust from Different Tree Species : Appropriateness of using them as adsorption media in wastewater and in stormwater treatment

Svensson, Henric January 2010 (has links)
Abstract   Bio energy in form of woodchips and sawdust is today commonly stored outdoors in heaps on hardened surfaces, exposed to weather and wind. Any water leaching from these heaps have the potential to be toxic to the environment. This paper examines the quality of the water leaching from heaps of four different tree species (oak, pine, maple and beech), by analysing different parameters such as pH, conductivity, colour, COD, BOD7, tannins & lignins (T&L) and phenols. The results show significant higher leaching values of COD, phenols, T&L and colour from oak compared to the other tree species (pine, maple and beech). These leached substances from woodchips and sawdust were shown in the BOD7 tests and BOD7/COD ratio values to be hard to biodegrade and are therefore not easily removed from the water. Hence it is important that wood-based fuel storage conditions are considered in bio energy generation schemes to ensure that the environmental benefits of using woodchips and sawdust instead of traditional fuel are not offset by the potential harm of inappropriate storage. The investigation further showed that leaching of highly toxic substances such as phenols can be up to 10 times higher for one tree type (oak) than another (pine, beech and maple). This difference could potentially be found for other tree species not characterized in this study.  Therefore, it is important to consider the constitution of the heaps to be able to apply appropriate storage conditions to avoid these toxic substances in the leached water reaching sensitive watercourses. As some of these substances are hard to biodegrade the treatment applied need a long retention time. Another problem is the carbon: nutrient ratio, this water has a high carbon content compared to phosphorus and nitrogen content which might prevent an efficient biodegradation. Adjusting C:N:P ratio with low cost amendments might raise the performance of the biodegradation in for instance, a constructed wetland.
7

Performance of vegetated roadsides in removing stormwater pollutants

Rammohan, Pavitra 16 August 2006 (has links)
Stormwater runoff from highways can contain pollutants such as suspended solids, nitrogen and phosphorus, organic material, and heavy metals. Growing awareness leading to regulatory requirements reflects the need to protect the environment from highway runoff effects. The management practice discussed in this study is the use of vegetated roadsides. The primary objective of this research is to document the potential treatment values from vegetated roadsides typical of common rural highway cross sections in two Texas cities: Austin and College Station. Three sites in each city were examined in this study over a 14-month monitoring period. No significant difference between the edges of pavement pollutant concentrations were observed at any of the research sites in the two study areas. This allowed for direct comparisons of the vegetated roadsides and their associated site characteristics such as annual daily traffic (ADT), dry period, and rainfall intensity. The scatter plots of College Station data show that concentrations of total suspended solids (TSS), total Pb, and chemical oxygen demand (COD) in runoff are dependent on the antecedent dry period and decrease with longer dry periods. The results show that pollutant concentrations are not highly dependent on ADT. However, the results show that the number of vehicles during the storm (VDS) was evaluated and accepted as a satisfactory independent variable for estimating the loads of total Pb and TSS. The results of correlation analysis show that the concentrations of total Pb and chemical oxygen demand are significantly correlated with TSS levels. The findings indicate that nitrate concentrations in runoff is most dependent on the average daily traffic using the highway during the preceding dry period as well as the duration of that dry period. Sites 2 and 3 in College Station are steeper but outperformed Site 1 which has much flatter slopes. This could be accounted for by the poor vegetative cover (brown patches) at Site 1. In the Austin sites, the permeable friction course appeared to have a significant impact on the quality of runoff leaving the road surface. On the whole, the results of this study indicate that vegetated roadsides could be used as a management practice for controlling and treating stormwater runoff from Texas highways.
8

Performance of vegetated roadsides in removing stormwater pollutants

Rammohan, Pavitra 16 August 2006 (has links)
Stormwater runoff from highways can contain pollutants such as suspended solids, nitrogen and phosphorus, organic material, and heavy metals. Growing awareness leading to regulatory requirements reflects the need to protect the environment from highway runoff effects. The management practice discussed in this study is the use of vegetated roadsides. The primary objective of this research is to document the potential treatment values from vegetated roadsides typical of common rural highway cross sections in two Texas cities: Austin and College Station. Three sites in each city were examined in this study over a 14-month monitoring period. No significant difference between the edges of pavement pollutant concentrations were observed at any of the research sites in the two study areas. This allowed for direct comparisons of the vegetated roadsides and their associated site characteristics such as annual daily traffic (ADT), dry period, and rainfall intensity. The scatter plots of College Station data show that concentrations of total suspended solids (TSS), total Pb, and chemical oxygen demand (COD) in runoff are dependent on the antecedent dry period and decrease with longer dry periods. The results show that pollutant concentrations are not highly dependent on ADT. However, the results show that the number of vehicles during the storm (VDS) was evaluated and accepted as a satisfactory independent variable for estimating the loads of total Pb and TSS. The results of correlation analysis show that the concentrations of total Pb and chemical oxygen demand are significantly correlated with TSS levels. The findings indicate that nitrate concentrations in runoff is most dependent on the average daily traffic using the highway during the preceding dry period as well as the duration of that dry period. Sites 2 and 3 in College Station are steeper but outperformed Site 1 which has much flatter slopes. This could be accounted for by the poor vegetative cover (brown patches) at Site 1. In the Austin sites, the permeable friction course appeared to have a significant impact on the quality of runoff leaving the road surface. On the whole, the results of this study indicate that vegetated roadsides could be used as a management practice for controlling and treating stormwater runoff from Texas highways.
9

Performance comparison of stormwater biofiltration designs

Limouzin, Maëlle 21 December 2010 (has links)
A biofiltration system is a stormwater Best Management Practice (BMP) that uses a biologically active filtration bed to remove contaminants. This type of BMP is preferred because it provides the opportunity for pollutant uptake (particularly nutrients) by vegetation in an aesthetically pleasing design. The goals of this research, proposed by the City of Austin, Texas, are to assess the role of plants in nutrient removal and to compare the pollutant removal effectiveness of biofiltration systems containing different media, plant species and designs. A laboratory column study was conducted with nineteen experiments using synthetic stormwater and one experiment using real stormwater. The results of this study show a significant improvement in nutrient removal with the presence of plants and a submerged zone with a carbon source in the filter. The columns without plants were found to export up to twice the nitrate/nitrite input, whereas the columns with plants showed significant removal of all nutrients (Nitrate 30-50%, Total Kjeldhal Nitrogen 65-85%, Total Phosphorus 80-90%). The difference between the two biofiltration media was not significant. Metals (Copper, Lead, Zinc) removal by all columns was very high (>95%) compared to similar field studies. Total Suspended Solids removal remained high through the whole set of experiments for all the columns (85- 95%). / text
10

The hydraulic design of infiltration drainage systems

Watkins, David Christopher January 2002 (has links)
No description available.

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