Matching Items (4)
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- All Subjects: infrastructure
- All Subjects: Leachate
- Creators: Civil, Environmental and Sustainable Engineering Programs
- Resource Type: Text
Description
There has been much work done predicting the effects of climate change on transportation systems, this research parallels that past work and focuses on the effect of changes in precipitation on roadway drainage systems. On a macro level, this work addresses the process that should be taken to make predictions about the vulnerability of this system due to changes in precipitation. This work also addresses the mechanisms of failure of these drainage systems and how they may be affected by changes in precipitation due to climate change. These changes may entail more frequent failure by certain mechanisms, or a shift in the mechanisms for particular infrastructure. A sample water basin in the urban environment of Phoenix, Arizona is given as a case study. This study looks at the mechanisms of failure of the infrastructure therein, as well as provides a process of analyzing the effects of increases in precipitation to the vulnerability of this infrastructure. It was found that drainage structures at roadways being currently designed will see increases from 20-30% in peak discharge, which will lead to increased frequency of failure.
ContributorsHolt, Nathan Thomas (Author) / Chester, Mikhail V (Thesis director) / Mascaro, Giuseppe (Committee member) / Underwood, Benjamin S. (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The culture of the 1970s in the United States of America was progressive and revolutionary. Due to various events that were unfavorable to the public, U.S. citizens began to lose trust in their government. Signs of the public's revolt and dissention began to show in laws and propositions voters passed. In California, Proposition 13 was one of many anti-tax laws taxpayers voted for to cut back the control of the government. As a result, revenues for public services and improvements decreased and maintenance allocations for infrastructure systems were considerably reduced. Fast-forwarding to today, infrastructure systems in the U.S. are reaching their retirement period and are requiring extreme maintenance and attention. Los Angeles has been experiencing severe water main breaks in its water distribution system for several years now, but the city is lacking funds to replace the aging pipes. The lack of funds paired with aging infrastructure indicates there is a flaw in the forecasting analysis techniques used today to project infrastructure costs. Therefore, an alternative discounting function to the exponential is proposed: the hyperbolic discounting function. A comparative analysis was performed using a hyperbolic and an exponential discounting function. The two functions were calibrated over the course of 50 years and the parameters r and a were determined. Then the discounts were applied to a 50-year expenditure projection for pipe replacements of a water distribution system. The present value was computed with each discount function and results were obtained. By year 50, the hyperbolic function yielded a higher present value of $25.06 million and the exponential function yielded a present value of $14 million. These results lead to the conclusion that the hyperbolic discounting function is the preferred methodology when calculating long-term expenditures, especially those dependent on tax revenue.
ContributorsSawyer, Madeline Elizabeth (Author) / Seager, Thomas (Thesis director) / Clark, Susan (Committee member) / McBurnett, Lauren (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Currently conventional Subtitle D landfills are the primary means of disposing of our waste in the United States. While this method of waste disposal aims at protecting the environment, it does so through the use of liners and caps that effectively freeze the breakdown of waste. Because this method can keep landfills active, and thus a potential groundwater threat for over a hundred years, I take an in depth look at the ability of bioreactor landfills to quickly stabilize waste. In the thesis I detail the current state of bioreactor landfill technologies, assessing the pros and cons of anaerobic and aerobic bioreactor technologies. Finally, with an industrial perspective, I conclude that moving on to bioreactor landfills as an alternative isn't as simple as it may first appear, and that it is a contextually specific solution that must be further refined before replacing current landfills.
ContributorsWhitten, George Avery (Author) / Kavazanjian, Edward (Thesis director) / Allenby, Braden (Committee member) / Houston, Sandra (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2013-05
Description
Zero-Valent Metals (ZVM) are highly reactive materials and have been proved to be effective in contaminant reduction in soils and groundwater remediation. In fact, zero-Valent Iron (ZVI) has proven to be very effective in removing, particularly chlorinated organics, heavy metals, and odorous sulfides. Addition of ZVI has also been proved in enhancing the methane gas generation in anaerobic digestion of activated sludge. However, no studies have been conducted regarding the effect of ZVM stimulation to Municipal Solid Waste (MSW) degradation. Therefore, a collaborative study was developed to manipulate microbial activity in the landfill bioreactors to favor methane production by adding ZVMs. This study focuses on evaluating the effects of added ZVM on the leachate generated from replicated lab scale landfill bioreactors. The specific objective was to investigate the effects of ZVMs addition on the organic and inorganic pollutants in leachate. The hypothesis here evaluated was that adding ZVM including ZVI and Zero Valent Manganese (ZVMn) will enhance the removal rates of the organic pollutants present in the leachate, likely by a putative higher rate of microbial metabolism. Test with six (4.23 gallons) bioreactors assembled with MSW collected from the Salt River Landfill and Southwest Regional Landfill showed that under 5 grams /liter of ZVI and 0.625 grams/liter of ZVMn additions, no significant difference was observed in the pH and temperature data of the leachate generated from these reactors. The conductivity data suggested the steady rise across all reactors over the period of time. The removal efficiency of sCOD was highest (27.112 mg/lit/day) for the reactors added with ZVMn at the end of 150 days for bottom layer, however the removal rate was highest (16.955 mg/lit/day) for ZVI after the end of 150 days of the middle layer. Similar trends in the results was observed in TC analysis. HPLC study indicated the dominance of the concentration of heptanoate and isovalerate were leachate generated from the bottom layer across all reactors. Heptanoate continued to dominate in the ZVMn added leachate even after middle layer injection. IC analysis concluded the chloride was dominant in the leachate generated from all the reactors and there was a steady increase in the chloride content over the period of time. Along with chloride, fluoride, bromide, nitrate, nitrite, phosphate and sulfate were also detected in considerable concentrations. In the summary, the addition of the zero valent metals has proved to be efficient in removal of the organics present in the leachate.
ContributorsPandit, Gandhar Abhay (Author) / Cadillo – Quiroz, Hinsby (Thesis advisor) / Olson, Larry (Thesis advisor) / Boyer, Treavor (Committee member) / Arizona State University (Publisher)
Created2019