Highways and roadways are the major source of stormwater runoff due to their prevalence and large non-permeable surface area. Best Management Practices (BMPs) such as bioswale provide effective on-site management and control of stormwater runoff from linear infrastructure such as highways. Many factors affect the performance of bioswales for stormwater volume reduction. The ratio of the installed BMP area to its service drainage area, characteristics of precipitation and the amount of sediment build-up over the surface of the BMP area are among the most important factors. Earlier studies have indicated that volume reductions in stormwater runoff from bioswale application range from 50% to 94%. However, the reported research lacks adequate information for a full understanding of how bioswales perform under various conditions. Consequently, additional systematic and in-depth research to better understand and the potential of bioswales as a method of controlling stormwater runoff is indicated. This research examined the effect of the following factors on bioswale performance: the ratio of the BMP area to the service drainage area, precipitation amounts and intensity, and sediment build-up. Hydraulic and hydrological processes were developed and analyzed through conceptual and physical models using appropriate governing equations including the Green-Ampt method. Field study of discrete rainfall events was conducted to collect information to calibrate and validate the numerical models. The field study tested various bioswale conditions with different levels of sediment accumulation. It also considered expected soil loss in the study area using the Universal Soil Loss Equation (USLE) method. In addition to field study, extensive simulations were conducted considering various contributing areas, rainfall depth and intensity, and sediment accumulation. These variables were manipulated to evaluate their effect on runoff volume reduction. Findings indicate that, for a given rainfall depth and duration, increasing the ratio of the BMP area to the service drainage area from 4% to16% results in increased bioswale efficiency ranging from 84% to 99%. The results revealed that input flowrate to the bioswale ranged from 0.04 to 4.7 in./min. depending on the rainfall intensity and soil type in the area. The runoff reduction performance of a newly constructed bioswale ranged from 44% for the highest input flowrate to 99% for the lowest input flowrate rainfall events. On the low end of rainfall volume/intensity, a 4% increase in the BMP area ratio results in a 34% improvement in efficiency (50% to 84%). On the high end of rainfall volume/intensity, a 16% increase in the area ratio results in only a 5% increase in efficiency (94% to 99%). Results also show that sediment accumulation has a substantial negative effect on infiltration rate. The observed efficiency of a bioswale in runoff reduction ranged from 13% to 100%. According to the USLE, the expected amount of soil loss occurring in the right-of-way area of a highway is approximately 1 ton/acre annually. The research revealed that for a given rainfall depth, duration, and area ratio; increasing the amount of sediment accumulation from 0 lbs./sq. ft. (equivalent to a newly constructed bioswale) to 2.7 lbs./sq. ft. (equivalent to a 10-year old bioswale) results in a 52% reduction in the runoff effectiveness of the bioswale sub-catchment from 98% to 46%. Finally, the physical model and associated governing equations were analyzed to describe the process of each studied factor. These results can be used for further study where the sediment accumulation rates differ from those modeled in this research.

No description available.

Sustainable Built Environments Senior Capstone Project / During Tucson rainstorms, many roads and neighborhoods experience high levels of flooding on the city’s street networks. This phenomenon creates unsafe road conditions, damage to the road infrastructure, and excessive urban stormwater runoff that is potentially polluted. The vast quantities of impervious surfaces in the urban landscape impede the rainwater’s ability to infiltrate the ground, thus resulting in increased volumes of runoff during a rainstorm. Stormwater management is used by municipalities and communities to address the previously mentioned adverse impacts of stormwater runoff. Various techniques and strategies used in stormwater management include, low impact development (LID), green infrastructure, and better site design (BSD) strategies implemented during design stages to reduce stormwater runoff levels. In addition, local governments can establish stormwater utilities and policies in order to help address and better manage the issue of stormwater runoff within urban areas. The primary research questions of this study will include: What are the most effective best management practices and techniques to address urban runoff? What combination of best management practices and government policies will be the more effective in addressing Tucson’s urban runoff problem? Accordingly, this study will examine a variety of policies and techniques to address stormwater runoff, and then, based on this information, provide a suggestion of the best practices and techniques that may be feasible for implementation in Tucson.

Sustainable Built Environments Senior Capstone Project / During Tucson rainstorms, many roads and neighborhoods experience high levels of flooding on the city’s street networks. This phenomenon creates unsafe road conditions, damage to the road infrastructure, and excessive urban stormwater runoff that is potentially polluted. The vast quantities of impervious surfaces in the urban landscape impede the rainwater’s ability to infiltrate the ground, thus resulting in increased volumes of runoff during a rainstorm. Stormwater management is used by municipalities and communities to address the previously mentioned adverse impacts of stormwater runoff. Various techniques and strategies used in stormwater management include, low impact development (LID), green infrastructure, and better site design (BSD) strategies implemented during design stages to reduce stormwater runoff levels. In addition, local governments can establish stormwater utilities and policies in order to help address and better manage the issue of stormwater runoff within urban areas. The primary research questions of this study will include: What are the most effective best management practices and techniques to address urban runoff? What combination of best management practices and government policies will be the more effective in addressing Tucson’s urban runoff problem? Accordingly, this study will examine a variety of policies and techniques to address stormwater runoff, and then, based on this information, provide a suggestion of the best practices and techniques that may be feasible for implementation in Tucson.

This research identified and evaluated possible uses of environmental monitoring data collected and reported by industrial facilities under the Clean Water Act requirements and determined whether the current regulatory system supported any of those uses. Federal policies and state-level policies in the United States, Florida, and California were evaluated in order to determine whether the current regulatory system supported any of the identified uses. Monitoring programs and currently available monitoring data were evaluated from Hillsborough County, Florida, and Los Angeles County, California, from the perspective of 1) the current implementation of the monitoring program, and 2) perfect implementation under full compliance with the monitoring program. Four possible uses for monitoring data were identified by this research: (1) identification of high polluting facilities within a given jurisdiction, (2) assessment of pollutant load to receiving waterbodies, (3) documentat ion of improvement over time in the amount of pollutants discharged from a given industrial facility, (4) self-evaluation purposes, such as identifying on-site pollutant sources, adapting pollution prevention efforts, and evaluating the monitoring protocol. The research conducted a telephone survey and evaluated industrial facilities' reported analytical monitoring data. Telephone questionnaires were administered to 63 industrial facilities, and analytical monitoring data were obtained from industrial facilities in Hillsborough County, Florida and Los Angeles County California. The representativeness, sampling frequency and variation in the industrial facilities' analytical monitoring data do not assist in the identification of high polluting facilities within a given jurisdiction nor provide for documentation of facilities' improvements. Pollutant loads to receiving watebodies can not be assessed through the use of industrial facilities' analytical monitoring data because of the sampl e measurement, variation, and sample frequency of the data. Therefore, these uses can not be supported under current implementation/current data submitted or under perfect compliance. However, the telephone survey revealed facility operators are attempting to use the results from monitoring for self evaluation purposes.

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Permeable Interlocking Concrete Pavements (PICP) have seen increased popularity in the principles of Water Sensitive Urban Design and Sustainable Drainage Systems in recent years. To address certain design queries that still existed in industry, a two-year experimental study was conducted. It entailed the construction of an Infiltration Table Apparatus and subjecting a representative volume of PICP to hydraulic testing within it. The study aimed at determining the controls of the flow of water into and through these pavements, the effect of variations in construction materials and incline on them, the validity of the hydraulic testing methods currently being applied to them in industry and lastly, to inform on their infiltration rates. A host of permeability data for PICP was gained and it was found that both the choice of materials and the incline on which PICP are constructed, can change their hydraulic properties drastically. In general, the selection of lower permeability materials in the surface portion of the layer works decreased the overall permeability of the pavement, while increases in inclines did the same. In addition, it was found that field investigation techniques require revision and further innovation before they can be effectively applied to PICP. / Dissertation (MSc)--University of Pretoria, 2019. / Bosun Brick (Pty) Ltd. / Geology / MSc / Unrestricted

No description available.

Green roofs are increasingly being used in the United States to mitigate the negative effects of impervious surfaces on aquatic ecosystems. Though performance of these systems varies with climate, little research has been conducted in the Southeastern U.S., and no prior research has been conducted in Mississippi. An experiment was conducted to determine the effect of soil depth and roof slope on the stormwater retention of green roofs in Mississippi’s hot, humid climate. Simulated roof platforms were constructed to investigate two soil depths and two slopes, each replicated three times and planted with four species of Sedum. The green roof platforms significantly reduced runoff depth when compared with total rainfall depth. Soil depth and slope both significantly affected retention, with higher retention seen with increasing soil depth and lower retention seen with increasing slope. These results indicate that green roofs can be an effective tool to reduce runoff in Mississippi.

Portland Cement pervious concrete's ability to permit water infiltration has encouraged its use as a stormwater management tool. However, the material has suffered historically poor support due to a number of factors, including failures due to poor mix design and improper construction techniques, concern about lesser structural strength, concern about poor long term performance due to clogging of surface pores and undefined credit for stormwater management. This study focuses on long term performances of pervious concrete parking lots and their stormwater management credit. Before stormwater management credit could be estimated, it was necessary to develop a testing device to gather information from existing pervious concrete parking lots currently in use. Eight parking lots were examined to determine the infiltration rates of the pervious concrete, as well as to verify the soil makeup beneath pavement. A total of 30 cores were extracted from pervious concrete parking lots and evaluated for infiltration rates. Three of the sites had a pervious concrete section that included a gravel reservoir. Infiltration rates were measured using the application of an embedded single-ring infiltrometer. In an attempt to provide an estimate of credit, a mass balance model was created to be used for simulation of the hydrologic and hydraulic function of pervious concrete sections. The purpose of the model is to predict runoff and recharge volumes for different rainfall conditions and hydraulic properties of the concrete and the soil. The field derived hydraulic data were used to simulate infiltration volumes and rainfall excess given a year of rainfall as used in a mass balance operated within a spreadsheet. The results can be used for assessing stormwater management credit.