This paper presents the results of an experimental study aimed at determining the impact of porous asphalt on the quality of stormwater runoff on highways with a curb and gutter drainage system. A porous overlay, also known as permeable friction course (PFC), is a layer of porous asphalt applied to the top of conventional asphalt highways at a thickness of 50 mm to improve safety and water quality and reduce noise. The quality of highway stormwater runoff was monitored before and after the installation of PFC on an eight-lane divided highway in the Austin, Texas area for 15 months. Observed concentrations of total suspended solids from PFC are more than an 80% lower than from the conventional pavement. Concentration reductions are also observed for nitrate/nitrite and total amounts of phosphorus, copper, lead, and zinc. The data shows that the results with curb and gutter are consistent with past results where runoff sheet flowed onto vegetated shoulders. / text

Thesis (Ph. D.) -- University of Maryland, College Park, 2007. / Thesis research directed by: Civil Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Stroubles Creek is registered on Virginiaâ s 303(d) list of impaired waters for both benthic and fecal coliform impairments. The upper reach of the creekâ s watershed drains into two ponds on the Virginia Tech campus. The area draining to the ponds, approximately 715 acres, encompasses most of the Town of Blacksburg and the Virginia Tech campus. Below the ponds, the creekâ s watershed is primarily forested and agricultural, with some areas of residential development. In order to improve water quality downstream, the two ponds will be converted to a water quality facility by redirecting all flow from the northern branch of Stroubles Creek into the upper, smaller pond, which then flows into the larger pond below. With flow into the upper pond increasing dramatically, the dam between the two ponds and associated overflow structures were evaluated and redesigned to protect the dam from overtopping and possible washout. In addition, concrete weirs were designed and will be constructed on both branches of Stroubles Creek above the ponds for future installation of flow and water quality monitoring equipment. Above the ponds, the banks along both branches of the creek have become severely eroded. Interlocking concrete block armoring was designed for the stream banks to reduce erosion and protect the trees growing along the creek. This project was jointly funded by Virginia Tech and a grant from the Virginia Department of Conservation and Recreation Water Quality Improvement Fund. Construction will be performed by the Capital Design department of Virginia Tech. / Master of Science

With a growing concern for the environment and increasing urbanization of rural areas, understanding the characteristics of urban non-point source pollution has become a focus for water quality investigators. Once thought to be a small contributor to the pollution problem, urban non-point sources are now responsible for transporting over 50% of all pollutants into natural waterways. Assessing non-point source pollution is the key to future water quality improvements in natural receiving waters. The purpose of this research was to investigate the water quality of an urbanized watershed, analyze current prediction methods and to investigate the effectiveness of an extended dry detention basin as a pollutant removal management practice on a 21.68-acre urban watershed on the Virginia Tech Campus. This research included extensive stormwater monitoring and sampling to characterize the runoff and water quality from an urban watershed. The resulting analysis included comparing well-known desktop prediction methods with pollutant removal rates using an extended dry detention basin and comparison with different literature values. Finally, the study team calibrated the PSRM-QUAL model for watershed prediction of non-point source runoff and pollution. The results of the stormwater monitoring process show that water quality prediction methods are not very successful on a storm by storm basis, but can be fairly accurate over longer periods of time with little or no storm water quality sampling. The extended dry detention basin is a simple yet effective management practice for the removal of sediments and sediment bound pollutants. / Master of Science

One of the many issues communities will face when trying to protect their local watershed is the lack of background their policy makers have in environmental protection and watershed health. The purpose of this study is to test a range of on-site stormwater management policies against a selection of new development projects from a specific small city of the United States in order to determine what combination of policies works best in a particular urban environment. Three policies were selected to test the range of stormwater approaches being used in the United States. These policies were then measured in a spreadsheet analysis against three years’ worth of new development from the city of Starkville, Mississippi. The outcomes of this research can provide communities and municipalities with a tool to help them determine which combination of application trigger and detention requirement for on-site stormwater management will best serve their watershed needs.

Proper stormwater management acknowledges both water quantity and water quality. Historically, stormwater quantity and quality have been separately considered; runoff was routed as quickly as possible into the nearest body of water. Although this alleviates potential flooding concerns, water quality is often compromised. Common stormwater quality problems include gross pollutants, sediment, nutrients, and heavy metals. The chronic elevated presence of these pollutants is detrimental to the environment. As a result, the government has passed legislature to protect waterways. The passage of the National Pollution Discharge Elimination System (NPDES) permit requires that municipalities implement stormwater treatment techniques, known as Best Management Practices (BMPs). Unfortunately, the NPDES document suggests treatment to the maximum extent possible, a vague description at best. This thesis reports a two-part study that endeavors to evaluate three of these proprietary treatment units manufactured by Stormceptor, BaySaver Separation Systems, and Continuous Deflective Separator (CDS) Technologies, Inc. to determine their performances. Each manufacturer produces a separator system that physically removes contaminants through the use of hydrodynamic flow principles. Phase I of the study focuses on monitoring two Stormceptor units and a CDS device in field conditions, while the second phase of the study evaluates each of the three treatment systems under laboratory conditions. The data analyses from the field study show the importance of proper maintenance. Storm events monitored after sump material removal showed great improvement over storm events occurring some time after the sump material removal. Furthermore, the treatment devices show a greater ability to remove pollutants from smaller storm events when compared with larger storm events. It is suggested that large storms cause scour of sediment previously trapped within the sump of the devices. An increase in the total suspended solid and nutrient concentrations, which were higher than the influent concentrations, was observed in both the field and laboratory studies. This could be explained by the fact that organics trapped by the treatment system decompose over time, therefore producing nutrient-rich water in the sump of the devices with higher concentration than the subsequent storm events. Some results are close to the minimum detection limit of the parameters being tested and small differences between influent and effluent load exaggerate the percent load differences. Consequently, there is little statistical significance between influent and effluent data, thus the data are summarized utilizing two methods. The methods include graphical representation of concentration and percent load difference, a method that normalized storms based on event size. In addition, a mass balance of gross litter was performed during the laboratory study.

The potential real-time control (RTC) has to improve the performance of existing stormwater management systems is a topic of increasing interest as hydraulic and hydrologic modeling capabilities proliferate. The benefits of incorporating precipitation forecast data into a RTC algorithm to allow for prediction-based control of an urban watershed is explored using an EPA SWMM 5.1 watershed model. One reactive and two predictive RTC algorithms are simulated in various configurations across seven dry detention ponds located in the 162 hectare urbanized watershed. The hydraulic benefits they provide at the site and watershed outlet in regards to peak flow and the flow duration curve are compared to conventional, static control. The ponds retrofit with the novel predictive RTC algorithm had lower peak flows during 24-hour design storms more consistently than when retrofit with reactive RTC. The duration of erosive flows at the site level was decreased by the novel predictive RTC in most cases. Improvements at the watershed outlet depended on where RTC was applied as hydrograph compounding was observed during some RTC implementations. / Master of Science / The consequences of watershed urbanization on nearby waterways has become a more relevant concern as urbanization increases and climate change continues to develop. Conventional stormwater management practices are employed to control peak flows from urbanized drainage areas for certain design storm criteria. Real-time control (RTC) technology has the potential to enable existing stormwater facilities to improve their performance during storm events different from their design conditions. This study compares the performance of several reactive and predictive rule-based RTC algorithms simulated as retrofits on seven dry detention ponds in a 162 hectare urbanized watershed. The results indicate that RTC algorithms that use rainfall forecast data for predictive decision making have the most potential to reduce stream erosion when applied appropriately throughout the watershed.

No description available.

<p>An approach to incorporate the effect of flood routing through a channel reach for use with the analytical probabilistic stormwater models (APSWM) was developed earlier in 2005. That earlier approach relied on adding the Muskingum K value of the channel reach into the catchment time of concentration and treating the whole drainage area including the channel reach as a lumped catchment. This is insufficient since other factors such as the X value in the Muskingum routing method also affects the routing results. In this study, a new approach to incorporate the routing effect of channel reaches in APSWM was developed where not only the K value but also the X value of a channel reach are considered. A number of continuous simulations were conducted to verify the proposed approach. It was demonstrated that the proposed approach performs better than the earlier one.</p> / Thesis / Master of Applied Science (MASc)

Excess nutrients, particularly phosphorus (P), significantly contribute to anthropogenic eutrophication, which negatively impacts ecosystems, human health, and the economy. Traditional Best Management Practices (BMPs) such as wet retention ponds prevent eutrophication by acting as a sink for nutrients, but can become a source of pollutants if not properly monitored and maintained. A proposed solution is a standalone, multi-stage filter system that can attach to BMPs with standing water for targeted removal of excess nutrients and with the potential to recycle the filter media. The studies in this dissertation seek to address the feasibility of this solution through the following tasks: 1.) develop a tool that can identify ponds and locations within ponds with high total phosphorus (TP) concentrations, 2.) evaluate filter media that can remove P and can be recycled along with captured P, and 3.) develop a filter system that can remove pollutants in separate stages for the option to recycle certain pollutants. The studies focused primarily on P because the nutrient has the potential to be recycled if captured within the filter. Models developed in the first task showed that TP concentrations in the water were correlated with the pond outlet, pH of the water, and iron concentrations. TP concentrations in the sediment were correlated with the pond's length-to-width ratio and the concentration of aluminum and copper. For the second task, a batch experiment and measurements of physicochemical properties were conducted on four biochars (corn stover pyrolized at 400°C , corn stover pyrolized at 600°C, mixed hardwood, and rice husk). Results indicated that mixed hardwood biochar could sorb dissolved phosphorus (DP) above a solution concentration of 2.9 mg P/L. The properties that could allow this biochar to sorb DP were a smaller negative surface charge, high surface area, smaller concentration of elemental P, and more water-extractable cations. A laboratory-scale test of a three-stage filter system was performed as part of the third task. The filter effectively separated nitrogen and P in different stages, but did not separate lead from P. Median water quality parameters (pH, conductivity, temperature, turbidity, dissolved oxygen, carbon, iron) met U.S. EPA recommended limits, but some parameters violated the recommended limits at a few time points. These studies demonstrate that excessive pollutant concentrations exist in current BMPs, which can benefit from a filter system. The filter system has the potential to collect pollutants separately provided that the correct media mix and configuration is identified such that P can be more completely isolated and water quality parameters are met. / PHD / Excess nutrients, particularly phosphorus (P), cause harmful algae blooms in the nation’s water bodies, which negatively impacts ecosystems, human health, and the economy. Structures such as wet retention ponds detain these nutrients by storing them, but can become a source of pollutants if not properly monitored and maintained. A proposed solution is a standalone, multi-stage filter system that can attach to wet retention ponds for targeted removal of excess nutrients and with the potential to recycle the filter media. The studies in this dissertation seek to address the feasibility of this solution through the following tasks: 1.) develop a tool that can identify ponds and locations within ponds with high total phosphorus (TP) concentrations, 2.) evaluate filter media that can remove dissolved P (DP) and can be recycled along with captured DP, and 3.) develop a filter system that can remove pollutants in separate stages for the option to recycle certain pollutants. The studies focused primarily on P because the nutrient has the potential to be recycled if captured within the filter. Models developed in the first task showed that TP concentrations in the water were correlated with the pond outlet, pH of the water, and iron concentrations. TP concentrations in the sediment were correlated with the pond’s length-to-width ratio and the concentration of aluminum and copper. For the second task, four biochars (corn stover pyrolized at 400°C, corn stover pyrolized at 600°C, mixed hardwood, and rice husk) were tested for their ability to collect DP. Only the mixed hardwood biochar was able to collect DP when the surrounding DP solution was higher than 2.9 mg P/L. A laboratory-scale test of a three-stage filter system was performed as part of the third task. The filter effectively separated nitrogen and P in different stages, but did not separate lead from P. Water quality parameters (pH, conductivity, temperature, turbidity, dissolved oxygen, carbon, iron) generally met U.S. EPA recommended limits, but some parameters violated the recommended limits at a few points in time. These studies demonstrate that excessive pollutant concentrations exist in current wet retention ponds, which can benefit from a filter system. The filter system has the potential to collect pollutants separately provided that the correct media mix and configuration is identified such that P can be more completely isolated and water quality parameters are met.