The performance of an urban stormwater bioretention management practice in the Kingsbrooke Subdivision of Prince William County, Virginia was examined over a one-year period. Bioretention is a relatively new urban stormwater best management practice (BMP) intended to mimic the pollutant-removal characteristics of an upland forest habitat. Typical bioretention areas utilize shallow ponding and highly-infiltrative sandy soils to treat the stormwater runoff from small commercial or residential drainage sites. The Kingsbrooke bioretention area was found to be atypical in several ways, including its relatively large, 14 acre, drainage area and the high clay content of its topsoil. Hydrologic and chemical data were collected by Virginia Tech staff for a total of 8 months in 2003 and 2004. Analysis of pollutant loading data was complicated by the presence of three unmeasured water flows: overland inflow bypassing the inflow gage, and groundwater flows both entering and exiting the bioretention soils. The BMP did reduce peak runoff rates for some storms, but did not significantly reduce total storm volumes because of the combined effects of the large drainage area to BMP area ratio and the poor infiltration capacity of the soil. Pollutant load calculations determined that the site removed about 28% of total suspended solids, 32% of total phosphorus, and about 15% of total nitrogen. Removals of approximately 16% and 7% were observed for lead and zinc, respectively. Although the Kingsbrooke bioretention area did improve water quality, the pollutant removal efficiencies were lower than those reported in the literature from more conventional bioretention areas. / Master of Science

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

Runoff from paved surfaces in the urban environment is recognised as a major contributing source to deteriorated water quality. In stormwater, both various metals and organic compounds can be present and the quality of stormwater is dependent on e.g. the characteristics of the surfaces that the runoff encounters. Diffuse pollution sources, i.e. anthropogenic emissions from e.g. traffic or constructions, has been pointed out by the European Water Framework Directive to significantly contribute to pollution of stormwater receivers. In order to create and obtain a sustainable, liveable and aesthetical urban environment it is critical to be able to mitigate stormwater pollution, not least considering the increasing amount of stormwater due to climate change.The aim of this master’s thesis was to evaluate the potential release of inorganic- and organic stormwater pollutants from conventional roofing materials by laboratory leaching experiments. The study was mainly aimed to serve as a first screening on the roofing materials, in order to be able to select a number of materials for further investigation later on. The organic compounds included in this study were polycyclic aromatic hydrocarbons, nonylphenols and -ethoxylates, phthalates and herbicides. Previous research on stormwater pollution has mainly focused on metals and there is therefore a knowledge gap on organic compounds in urban runoff. The leaching experiments were designed considering previous similar studies. Synthetic rainwater was prepared based on measurements of rainwater quality in Sweden. Duplicates of 16 commonly used roofing materials were prepared and immersed in beakers of synthetic rainwater. The beakers were agitated on an orbital shaking device for 24 hours and pH as well as conductivity was recorded in the leachates before sending the samples to the contracted laboratory for analysis. Metals were analysed on all materials and the organic compound analyses were performed on selected materials based on each material’s composition and was limited with the substance’s probability to release from each material.From the analysis results, mean values for the leached concentrations of all duplicates were calculated. The annual potential release of substances from materials was estimated based on the leached concentrations and data on the average annual precipitation in Sweden, in order to get an indication of the order of magnitude of the pollutant release. The results showed a potential release of a number of the included substances from many of the studied roofing materials, in varying order of magnitude. The shingle roofing was the material that showed the ability to release the largest number of pollutants. Some materials e.g. the clay tile also showed potential to adsorb substances on the material surface. Metals were mainly released in dissolved form from most materials. Phthalates were not present in concentrations above report limits in the leachates from any of the studied materials. The results also indicate a significant different in the release potential from materials that were considered similar in their composition and expected to have similar leaching behaviour prior to the laboratory experiments, e.g. two similar felt roof materials from different manufacturers. / <p>Validerat; 20150715 (global_studentproject_submitter)</p>

Extended detention basins are not used for stormwater quality management in many areas of the US because they generally do not achieve the 80% removal of total suspended solids required by many regulatory agencies. The objective of this research was modification of the outlet controls of an existing basin to provide batch treatment of the urban stormwater runoff through efficient control of the hydraulic residence time. A solar powered automated valve and controller were developed and placed on the outlet of an extended detention basin in Austin, Texas to increase the detention time beyond the times achievable using an orifice. This system retained the diverted runoff in the basin for a variable preset period of time. The quality of the influent and effluent of the basin was monitored for concentrations of suspended solids, nutrients, chemical oxygen demand. and total and dissolved metals. The suspended solids concentrations in the basin were controlled by adjusting the residence time of the runoff in the basin to meet the required pollutant reduction. The automated valve can also be used to regulate flow into the receiving waters to control peak flow.

Pervious pavements in car parks and driveways reduce peak discharge and the volume of runoff flowing in to urban drains and improve the water quality by trapping the sediments in the infiltrated water. This reduces the risk of pollutants such as suspended solids and particle bound chemicals such as phosphorous, nitrogen, heavy metals and oils and hydrocarbons entering receiving waters. The key objectives of the study are to establish relationships between rainfall and pervious pavement runoff and quantify improvements to infiltrated stormwater quality through the pervious pavement. The field experimental results were used to calibrate the PCSWMMPP model and to develop water flow and quality improvement transfer functions of the MUSIC model for concrete block and turf cell pavements. The research reported herein has demonstrated that pervious pavements can be introduced as a sustainable stormwater management initiative and as a key Water Sensitive Urban Design feature to deliver numerous benefits to the environment. The outcomes from the study will be useful in designing environmentally friendly car parks, pedestrian paths, light traffic drive ways, sporting grounds and public areas in the future. Land developers and local government authorities will be major beneficiaries of the study which has increased the understanding of the use of pervious pavements and explored a number of issues that previously inhibited the wider use of pervious pavements in practice.

Accurate and reliable estimations are the most important factors for the development of efficient stormwater pollutant mitigation strategies. Modelling is the primary tool used for such estimations. The general architecture of typical modelling approaches is to replicate pollutant processes along with hydrologic processes on catchment surfaces. However, due to the lack of understanding of these pollutant processes and the underlying physical parameters, the estimations are subjected to gross errors. Furthermore, the essential requirement of model calibration leads to significant data and resource requirements. This underlines the necessity for simplified and robust stormwater pollutant estimation procedures. The research described in this thesis primarily details the extensive knowledge developed on pollutant build-up and wash-off processes. Knowledge on both build-up and wash-off were generated by in-depth field investigations conducted on residential road and roof surfaces. Additionally, the research describes the use of a rainfall simulator as a tool in urban water quality research. The rainfall simulator was used to collect runoff samples from small-plot surfaces. The use of a rainfall simulator reduced the number of variables which are common to pollutant wash-off. Pollutant build-up on road and roof surfaces was found to be rapid during the initial time period and the rate reduced when the antecedent dry days increase becoming asymptote to a constant value. However, build-up on roofs was gradual when compared to road surfaces where the build-up on the first two days was 66% of the total build-up. Though the variations were different, it was possible to develop a common replication equation in the form of a power function for build-up for the two surface types with a as a multiplication coefficient and b as a power coefficient. However, the values for the two build-up equation coefficients, a, and b were different in each case. It was understood that the power coefficient b varies only with the surface type. The multiplication coefficient varies with a range of parameters including land-use and traffic volume. Additionally, the build-up observed on road surfaces was highly dynamic. It was found that pollutant re-distribution occurs with finer particles being removed from the surface thus allowing coarser particles to build up. This process results in changes to the particle size composition of build-up. However, little evidence was noted of re-distribution of pollutants on roof surfaces. Furthermore, the particulate pollutants in both road and roof surfaces were high in adsorption capacity. More than 50% of the road and more than 60% of the roof surface particulates were finer than 100 μm which increases the capacity to adsorb other pollutants such as heavy metals and hydrocarbons. In addition, the samples contained a significant amount of DOC which would enhance the solubility of other pollutants. The wash-off investigations on road and roof surfaces showed a high concentration of solid pollutants during the initial part of events. This confirmed the occurrence of the 'first flush' phenomenon. The observed wash-off patterns for road and roof surfaces were able to be mathematically replicated using an exponential equation. The exponential equation proposed is a modified version of an equation proposed in past research. The modification was primarily in terms of an additional parameter referred to as the 'capacity factor' (CF). CF defines the rainfall's ability to mobilise solid pollutants from a given surface. It was noted that CF varies with rainfall intensity, particle size distribution and surface characteristics. Additional to the mathematical replication of wash-off, analysis further focused on understanding the physical processes governing wash-off. For this, both particle size distribution and physicochemical parameters of wash-off pollutants were analysed. It was noted that there is little variation in the particle size distribution of particulates in wash-off with rainfall intensity and duration. This suggested that particle size is not an influential parameter in wash-off. It is hypothesised that the particulate density and adhesion to road surfaces are the primary criteria that govern wash-off. Additionally, significantly high pollutant contribution from roof surfaces was noted. This justifies the significance of roof surfaces as an urban pollutant source particularly in the case of first flush. This dissertation further describes a procedure to translate the knowledge created on pollutant build-up and wash-off processes using small-plots to urban catchment scale. This leads to a simple and robust urban water quality estimation tool. Due to its basic architecture, the estimation tool is referred to as a 'translation procedure'. It is designed to operate without a calibration process which would require a large amount of data. This is done by using the pollutant nature of the catchment in terms of buildup and wash-off processes as the basis of measurements. Therefore, the translation procedure is an extension of the current estimation techniques which are typically complex and resource consuming. The use of a translation procedure is simple and based on the graphical estimation of parameters and tabular form of calculations. The translation procedure developed is particularly accurate in estimating water quality in the initial part of runoff events.

Urbanization causes various environmental issues including water pollution, air pollution, and solid waste. Urbanization of watersheds has a profound influence on the quality of stormwater runoff. The quality of stormwater runoff is highly associated with land use. This study analyzed the exceedance frequency of stormwater quality in five watersheds of Denton over eleven years and also analyzed the relationship between stormwater quality and land use/cover of each watershed. The results showed that the most of the water quality parameters that were examined in the Lower Pecan watershed exceeded their threshold most frequently. The higher frequency of exceedance in this watershed can be attributed to the wastewater treatment plant and landfill site. Total suspended solids and turbidity were frequently exceeded in Hickory and Clear Creek watersheds. Conductivity was found to have highest percentage of exceedance in Upper Pecan and Cooper watersheds. Thus, rural watersheds were related with higher exceedance of TSS and turbidity whereas urban watersheds were related with higher exceedance of conductivity.

This dissertation argues that stormwater management is fragmented both at that vertical fragmentation (at the level of intergovernmental relations) and horizontal fragmentation (within the level of governments). The first essay focuses on the institutional arrangements used by states to implement stormwater management policies. Building on the race to the bottom literature, I examine the impact of the institutional arrangement centralization on state water quality in California, Texas, Virginia, and Minnesota. A five-year (2013-2018) permitting cycle was used to analyze five dimensions: formalism, coercion, education, prioritization, and accommodation.There is an inverse relationship between the quality of stormwater and the degree of centralization in the institutional arrangements adopted by state governments to implement their stormwater management policies. The second essay focuses on a local government's decision to join an inter-local agreement to comply with federal/state stormwater management policies. Building on the transaction cost framework, the study used a cross-sectional design to analyze a case study. The case study consists of 119 cities subjected to stormwater regulation requirements in northern Texas during 2017. The dependent variable is the membership of the regional inter-local agreement, and the independent variables are the number of neighboring cities and population density. Community wealth, public works spending, stormwater fees, government type, and the percent of the population over 65 were used as control variables. Logistic regression was used for data analysis. This study concludes that the increase in the number of neighboring regulated local governments is associated with an increase in the likelihood of a decision by the regulated local government to join an interlocal agreement (ILA), as well as finding that an increase in the population density is associated with an increase in the likelihood of a decision by the regulated local government to join the ILA. In addition, the study found that the type of government also affects a decision to enter into a cooperative relationship to meet the regulative burdens associated with implementing the stormwater management policies imposed by state/federal governments. The results found in this dissertation contribute to bridging the gap in our knowledge on the impact of the institutional framework adopted by the states to implement environmental policy through empirically evaluating the effect of institutional arrangements (as represented in the States general MS4 permits) on the policy output (reducing the level of stormwater pollution).

This thesis investigates the effectiveness of Low Impact Development Infrastructure (LIDI) and Green Infrastructure (GI) in reducing flooding resulting from heavy rainfall events and sea-level rise, and in improving stormwater quality in the City of Miami Beach (CMB). InfoSWMM was used to simulate the 5, 10, and 100-year, 24-hour storm events, total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) loadings, and in evaluating the potential of selected LIDI and GI solutions in North Shore neighborhood. Post-development results revealed a decrease of 48%, 46%, and 39% in runoff, a decrease of 57%, 60%, and 62% in TSS, a decrease of 82%, 82%, and 84% in BOD, and a decrease of 69%, 69%, and 70% in COD loadings. SWMM 5.1 was also used to simulate the king tide effect in a cross section in Indian Creek Drive. The proposed design simulations successfully demonstrated the potential to control flooding, showing that innovative technologies offer the city opportunities to cope with climate impacts. This study should be most helpful to the CMB to support its management of flooding under any adaptation scenarios that may possibly result from climate changes. Flooding could be again caused as a result of changes in inland flooding from precipitation patterns or from sea-level rise or both.

Le développement des réseaux séparatifs entraîne le transfert fréquent de polluants urbains vers les milieux récepteurs (plans d’eau, rivières, etc.). La compréhension des processus de production et de lessivage des polluants dans le milieu urbain est pourtant incomplète à l’heure actuelle. Afin de répondre aux questions liées à la gestion des eaux urbaines, l’amélioration des connaissances des processus physiques est nécessaire, tant au niveau des surfaces urbaines que les réseaux d'assainissement. Pour cela, la modélisation du transfert hydrologique des polluants en milieu urbain peut être un outil précieux.Cette thèse a pour objectif de développer et d'analyser des modèles distribués à base physique pour simuler les flux de polluants routiers (Matières En Suspension (MES), Hydrocarbures, Métaux) dans un environnement urbain. Elle s'inscrit dans le cadre du projet ANR "Trafipollu" et bénéficie des résultats expérimentaux mis en œuvre dans ce projet pour la calibration et validation des modèles utilisés. Le travail de thèse s’articule autour de deux échelles de modélisation : l’échelle locale et l’échelle du quartier.A l'échelle locale, le code FullSWOF (volumes finis, schéma numérique d'ordre 2) couplé au modèle d’érosion d'Hairsine and Rose (1992a; 1992b) et des données géographiques très détaillées (résolution spatiale centimétrique) ont été utilisés et adaptés afin d'améliorer nos connaissances des processus physiques du lessivage des polluants sur les surfaces urbaines. La comparaison aux mesures en continu permet d’évaluer la performance d’une modélisation physique pour représenter les variations spatiales et temporelles des processus de transferts des polluants sur les surfaces urbaines. Les analyses des résultats obtenus permettent de constater la prédominance des effets d'arrachement liés à la pluie sur les processus d'entrainement par l'advection sur la majeure partie du bassin versant routier. L’utilisation d’un modèle d’érosion pour modéliser le transport particulaire en zone urbaine est une innovation importante de cette thèse.A l’échelle du quartier, la deuxième étape du travail consiste à coupler séquentiellement le modèle TREX (Velleux, England, et al., 2008) avec le modèle CANOE (Alison, 2005), nommé "TRENOE" plateforme. En changeant différentes options de mise en œuvre et de configurations du modèle, l’adaptation de la précision numérique et l’utilisation de données détaillées d’occupation du sol semblent être les facteurs clés pour une telle modélisation. Par ailleurs, ce couplage a montré des problèmes de fond tels que la modélisation du schéma numérique des flux en surface (seulement dans 4 directions), ainsi que l'utilisation de l'équation USLE pour simuler l'érosion en milieu urbain, ne comprenant pas d’impact des gouttes de pluie pour la modélisation.Pour remédier à ces défauts, la plateforme opensource LISEM-SWMM est développée en couplant le modèle LISEM (De Roo, Wesseling, et al., 1996), modèle d’érosion développé initialement pour le milieu naturel, et le modèle SWMM (Rossman, 2010). Pour la première fois, la modélisation hydrologique s’appuie aussi sur l’utilisation de sorties de modèles atmosphériques pour les dépôts des particules fines (PM10), hydrocarbures et métaux. Les résultats montrent que l’emploi de modèles totalement distribués peut arriver à reproduire de manière très fine les dynamiques des particules, des hydrocarbures et des métaux. Même si à ce stade la plateforme développée nécessite des améliorations pour adapter aux utilisations dans le champ opérationnel, ceci constitue une avancée pour le domaine de modélisation du transfert hydrologique des polluants routiers en milieu urbain / Nowadays, the increasing use of separate stormwater systems causes a frequent transport of urban pollutants into receiving water bodies (lakes, rivers). However, current studies still lack of the knowledge of urban build-up and wash-off processes. In order to address urban management issues, better understanding of physical mechanism is required not only for the urban surfaces, but also for the sewer systems. In this context, the modelling of hydrological transfer of urban pollutants can be a valuable tool.This thesis aims to develop and assess the physically-based and distributed models to simulate the transport of traffic-related pollutants (suspended solids, hydrocarbons, heavy metals) in urban stormwater runoffs. This work is part of the ANR "Trafipollu" project, and benefit from the experimental results for model calibration and validation. The modelling is performed at two scales of the urban environment: at the local scale and at the city district scale.At the local scale of urban environment, the code FullSWOF (second-order finite volume scheme) coupled with Hairsine and Rose model (1992a; 1992b) and detailed monitoring surveys is used to evaluate urban wash-off process. Simulations over different rainfall events represent promising results in reproducing the various dynamics of water flows and particle transfer on the urban surfaces. Spatial analysis of wash-off process reveals that the rainfall-driven impacts are two orders of magnitude higher than flow-drive effects. These findings contribute to a significant improvement in the field of urban wash-off modelling. The application of soil erosion model to the urban context is also an important innovation.At the city district scale, the second step consists of coupling the TREX model (Velleux, England, et al., 2008) and the CANOE model, named "TRENOE" platform. By altering different options of model configurations, the adequate numerical precision and the detailed information of landuse data are identified as the crucial elements for achieving acceptable simulations. Contrarily, the high-resolution topographic data and the common variations of the water flow parameters are not equally significant at the scale of a small urban catchment. Moreover, this coupling showed fundamental problems of the model structure such as the numerical scheme of the overland flow (only 4 directions), and the empirical USLE equations need to be completed by raindrop detachment process.To address these shortcomings, the LISEM - SWMM platform is developed by coupling the open-source LISEM model (De Roo, Wesseling, et al., 1996), which is initially developed for soil erosion simulations, and the SWMM model (Rossman, 2010). For the first time, the hydrological model is also supported by the simulations of atmospheric dry deposits of fine particles (PM10), hydrocarbons and heavy metals. The performance of water flow and TSS simulations are satisfying with the calibrated parameters. Considering the hydrocarbons and heavy metals contents of different particle size classes, simulated event mean concentration of each pollutant is comparable to local in-situ measurements. Although the platform at current stage still needs improvements in order to adapt to the operational applications, the present modelling approach contributes to an innovative technology in the field of modelling of hydrological transfer of the traffic-related pollutants in urban environment