Browsing by Subject "Stormwater"
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Item Analysis of stormwater runoff from permeable friction course(2009-12) Frasier, Patrick Martin; Charbeneau, Randall J.; Barrett, Michael E.Recently, the Texas Department of Transportation began using Permeable Friction Course (PFC), a 5 cm overlay of porous pavement that is applied over conventional pavement. PFC was initially developed because it allows water to drain off the surface of roads much more rapidly, thus reducing visual impairment due to splash and spray as well as reducing the risk of hydroplaning. While investigating the water quality of stormwater runoff, researchers at the University of Texas discovered that PFC caused a reduction in many common stormwater pollutant concentrations. Monitoring of stormwater at one site has been ongoing for 5 years without any indication of a decline in water quality. A second location provided paired samples to analyze the particle size distribution. Results show a significant reduction in the mass of particles commonly associated with heavy metals and nutrient loads. A third location was chosen based on tests indicating it to have a lower hydraulic conductivity relative to other locations. The paired samples provided a comparison of runoff quality at a site believed to be heavily clogged. The results show PFC continues to produce significantly lower runoff pollutant concentrations despite the decreased hydraulic conductivity.Item Evaluation of compost specifications for stormwater management(2009-05-15) Birt, Lindsay NicoleUrban development will continue to increase in Texas because of population growth and urban sprawl. Despite the desire for urbanization and expansion of the economy, this growth increases the amount of construction, which, if not properly managed, can increase non-point source pollution and threaten surface water quality. Therefore, Texas Department of Transportation (TxDOT) has approved and promoted the use of compost as a stormwater best management practice (BMP) during highway construction. The objectives of this study were to construct and calibrate an indoor rainfall simulator and to determine the effectiveness of using compost rather than conventional hydroseeding or topsoil to reduce erosion from disturbed soils. Runoff rates, interrill erosion, and interrill erodibility were determined and compared across five compost treatments following TxDOT specifications for compost applied as an erosion control and two control treatments of topsoil (TS) and hydroseeding (HS) applied at 5 cm depth. The simulator produced 89% uniformity using ten Veejet 80100 nozzles at a target rate of 100 mm h-1. The surface runoff was collected after 5 minutes of rainfall (first flush) and during the last 30 minutes of rainfall (steady-state). The first flush mean runoff for GUC-5 treatment was significantly higher than all other treatments. All other treatments; 50% woodchips and 50% compost blend (ECC-1.3, ECC-5), and hydroseeding (HS) had significantly lower runoff and erosion rates compared to topsoil (TS) and compost manufactured topsoil (CMT) at first flush and steady-state. Furthermore, there were no performance differences between 1.3 cm and 5 cm compost applications at first flush or steady-state. The results of this project indicate that particle size, soil moisture capabilities, and time at which rainfall is applied affect surface runoff. TxDOT specification of using ECC at 5 cm depth on a max of 3:1 slope should be reconsidered. An ECC application depth of 1.3 cm was effective in reducing first flush runoff and interrill erosion rates.Item Investigating Rainwater Harvesting as a Stormwater Best Management Practice and as a Function of Irrigation Water Use(2012-02-14) Shannak, Sa'D Abdel-HalimStormwater runoff has negative impacts on water resources, human health and environment. In this research the effectiveness of Rain Water Harvesting (RWH) systems is examined as a stormwater Best Management Practice (BMP). Time-based, evapotranspiration-based, and soil moisture-based irrigation scheduling methods in conjunction with RWH and a control site without RWH were simulated to determine the effect of RWH as a BMP on a single-family residence scale. The effects of each irrigation scheduling method on minimizing water runoff leaving the plots and potable water input for irrigation were compared. The scenario that reflects urban development was simulated and compared to other RWH-irrigation scheduling systems by a control treatment without a RWH component. Four soil types (sand, sandy loam, loamy sand, silty clay) and four cistern sizes (208L, 416L, 624L, 833L) were evaluated in the urban development scenario. To achieve the purpose of this study; a model was developed to simulate daily water balance for the three treatments. Irrigation volumes and water runoff were compared for four soil types and four cistern sizes. Comparisons between total volumes of water runoff were estimated by utilizing different soil types, while comparisons between total potable water used for irrigation were estimated by utilizing different irrigation scheduling methods. This research showed that both Curve Number method and Mass-Balance method resulted in the greatest volumes of water runoff predicted for Silty Clay soil and the least volumes of water runoff predicted for Sand soil. Moreover, increasing cistern sizes resulted in reducing total water runoff and potable water used for irrigation, although not at a statistically significant level. Control treatment that does not utilize a cistern had the greatest volumes of predicted supplemental water among all soil types utilized, while Soil Moisture-based treatment on average had the least volume of predicted supplemental water.Item Modeling stormwater sewer systems using high resolution data(2014-05) Galdeano Alexandres, Carlos; Maidment, David R.More than 54% of the world population lives in urban areas, and this percentage is projected to increase rapidly in future years. This growth significantly affects the hydrological cycle, which translates into social and economic costs due to urban flooding. This thesis develops a procedure to evaluate the current storm water infrastructure using Airborne LiDAR data. This evaluation is essential to mitigate and prevent the effect of floods in urban areas. Airborne LiDAR data provides the elevation data necessary to characterize the elements involved in the storm water system. The processing of this data, digitization, and characterization of the storm drainage system is computed with ArcGIS, Geographic Information System (GIS) software. Scenarios for 4 return periods (2, 10, 25 and 100 years) are modeled using StormCAD in order to evaluate the capacity of the stormwater sewer system in the northwest area of The University of Texas at Austin main campus. The performance of the drainage system might work under strain for a 100-year storm event; therefore, it is suggested to modify the pipe sizes to prevent flooding in the area analyzed. The results indicate that the methodology proposed for evaluating the current conditions of a stormwater drainage system produces valid results, but can be improved using Ground-based LiDAR data.Item Performance comparison of stormwater biofiltration designs(2010-08) Limouzin, Maëlle; Barrett, Michael E.; Lawler, Desmond F.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%).Item Reducing turbidity of construction site runoff via coagulation with polyacrylamide and chitosan(2012-05) Rounce, David Robert; Lawler, Desmond F.; Barrett, Michael E.The U.S. Environmental Protection Agency is in the process of developing a nationwide standard for turbidity in construction site runoff. It is widely expected that this standard cannot be met with conventional erosion and sediment control measures; consequently, innovative practices for managing sediment on construction sites must be developed. The objective of this research was to develop an understanding of how soil characteristics and polymer properties affect the amount of turbidity reduction that can be achieved through flocculation. The polymers used were PAMs, a proprietary product, and chitosan. The charge density of the PAMs ranged from 0% to 50% and the molecular weights ranged from 0.2 to 14 Mg/mol. A protocol for creating modified synthetic stormwater runoff for soil samples was developed and used on soils from seven construction sites. Particle size distributions were used to compare the modified synthetic stormwater runoff with grab samples of stormwater from one site and showed the synthetic runoff was representative of the actual runoff. Flocculation tests were performed on the synthetic runoffs with PAM and chitosan doses from 0.03 to 10 mg/L. The non-ionic PAM, proprietary product, and chitosan were found to be the most effective at reducing the turbidity of all the synthetic runoff below 200 NTU. The high molecular weight anionic PAMs were effective on only two of the seven synthetic runoff samples. Hardness tests were performed indicating interparticle bridging to be the bonding mechanism of the PAM. Electrophoretic mobility tests were performed on two of the soil suspensions and indicated the bonding mechanism of PAM to be interparticle bridging, and the bonding mechanism of chitosan to be a combination of charge neutralization and interparticle bridging. Tests showed as the charge density of the PAM increased, their effectiveness decreased.Item The relationship between urban design, water quality, and quality of life(2006-08) Stewart, Justin Thomas; McMillan, Tracy E.This report uncovers relationships between water quality and quality of life (QOL) through urban design. It shows that Smart Growth (a type of urban design) is a reasonable management practice for stormwater that can also positively affect our quality of life. This study is meant to support and inspire further research on how to link quantitative measurements of QOL with quantitative measurements of water quality through urban design characteristics. The report will introduce an ongoing study by PhD candidate, Suzanne Pierce, as her and her team currently combine water quantity/quality science with decision making. They are using the stakeholder process I served on, The Barton Springs Regional Water Quality Plan 2005, as a test bed for their creation. My hope is that this study will serve as a collection of data that Pierce’s group can draw from as they get closer to illustrating design choices for stakeholders as well as linking those choices to water quality and QOL.Item Retrofit of an existing flood control facility to improve pollutant removal in an urban watershed(2014-05) Gilpin, Amy Christine; Barrett, Michael E.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.Item Rising tide : stormwater management, historic preservation, and sustainable redevelopment in Houston’s Fifth Ward(2014-05) Kobetis, Sarah Bridget; Holleran, MichaelHouston's Fifth Ward neighborhood is one of the last remaining areas of the inner city to have not yet seen large-scale redevelopment. Situated just northeast of downtown, the neighborhood's population is predominantly low- to mid-income African Americans; demographics are similar today as they were during the neighborhood's prime, from the 1920s-60s, when the Fifth Ward was a cultural hub of Houston famous for its musical culture of zydeco and blues. The ward's rich history also has dark spots, however, specifically its longstanding reputation as a center of poverty and violent crime, and its physical vulnerability to damaging floods. Much of the neighborhood's built history is unpreserved and unprotected, at risk of being wiped off the map by both development interests and extreme weather events. By modernizing the city's approach to stormwater management and infrastructure and strengthening its historic preservation and emergency management practices, Houston could help preserve one of its oldest communities, while also decreasing flood volumes, improving air and water quality, saving money, and establishing a pattern of smart growth citywide. In addition, neighborhood level efforts to promote placemaking via preservation and sustainability efforts can help the Fifth Ward leverage the redevelopment process to change its reputation, ensuring a future for the community that respects its past.