Dissertations / Theses on the topic 'Stormwater pollutants'

Urban runoff is generated by precipitation of rain and snowmelt on impervious surfaces.  The increasing demand of urbanization causes contaminants to accumulate on roads,  roofs and pathways. In turn, as runoff wash off these surfaces, contaminants such as heavy metals, particles and organic pollutants end up in the stormwater. Urban stormwater ponds improve water quality of runoff by facilitating contaminants in form of particles. To preserve the function of a stormwater pond accumulated sediment must periodically be removed.Therefore, upland disposal alternatives should be evaluated. This study examined stormwater sediment and outlet stormwater quality in seven and four ponds respectively in the vicinity of Halmstad. 7 heavy metals and 24 organic contaminants were analysed in both sediments and stormwater. Results showed metal and organic contaminant concentrations in stormwater pond discharge and sediment exceeding concentrations reported in guideline values. From the analysed heavy metals, Zn and Pb was considered the most critical contaminants. Heavier organic compounds were more frequently quantified than lighter ones, where 42 % of the analysed organic contaminants were quantified in at least one sample. Variability between inlets and outlets, between ponds and between sampling occasions was observed. The observed variability suggests that the contamination level is influenced by catchment area characteristics and activities. Significant correlation from Spearman’s rank correlation was found between the individual heavy metals (Cu, Cr, Ni, Pb and Zn), which suggest they originate from similar sources

Stormwater runoff from highways can contain pollutants such as suspended solids, nitrogen and phosphorus, organic material, and heavy metals. Growing awareness leading to regulatory requirements reflects the need to protect the environment from highway runoff effects. The management practice discussed in this study is the use of vegetated roadsides. The primary objective of this research is to document the potential treatment values from vegetated roadsides typical of common rural highway cross sections in two Texas cities: Austin and College Station. Three sites in each city were examined in this study over a 14-month monitoring period. No significant difference between the edges of pavement pollutant concentrations were observed at any of the research sites in the two study areas. This allowed for direct comparisons of the vegetated roadsides and their associated site characteristics such as annual daily traffic (ADT), dry period, and rainfall intensity. The scatter plots of College Station data show that concentrations of total suspended solids (TSS), total Pb, and chemical oxygen demand (COD) in runoff are dependent on the antecedent dry period and decrease with longer dry periods. The results show that pollutant concentrations are not highly dependent on ADT. However, the results show that the number of vehicles during the storm (VDS) was evaluated and accepted as a satisfactory independent variable for estimating the loads of total Pb and TSS. The results of correlation analysis show that the concentrations of total Pb and chemical oxygen demand are significantly correlated with TSS levels. The findings indicate that nitrate concentrations in runoff is most dependent on the average daily traffic using the highway during the preceding dry period as well as the duration of that dry period. Sites 2 and 3 in College Station are steeper but outperformed Site 1 which has much flatter slopes. This could be accounted for by the poor vegetative cover (brown patches) at Site 1. In the Austin sites, the permeable friction course appeared to have a significant impact on the quality of runoff leaving the road surface. On the whole, the results of this study indicate that vegetated roadsides could be used as a management practice for controlling and treating stormwater runoff from Texas highways.

The research concerned the assessment of the pathways utilized by heavy metal pollutants in urban stormwater runoff. A separately sewered urban residential catchment of approximately 107 hectares in Chelmsley Wood, north-east Birmingham was the subject of the field investigation. The catchment area, almost entirely residential, had no immediate industrial heavy metal input, however, industry was situated to the north of the catchment. The perimeter of the catchment was bounded by the M6 motorway on the northern and eastern sides and was believed to contribute to aerial deposition. Metal inputs to the ground surface were assumed to be confined to normal suburban activities, namely, aerial deposition, vehicular activity and anthropological activities. A programme of field work was undertaken over a 12 month period, from July 1983 to July 1984. Monthly deposition rates were monitored using a network of deposit cannisters and roadside sediment and soil samples were taken. Stormwater samples were obtained for 19 separate events. All samples were analysed for iron, lead, zinc, copper, chromium, nickel and cadmium content. Rainfall was recorded on site with additional meteorological data obtained from local Meteorological Offices. Use was made of a simple conceptual model designed for the catchment to substantiate hypotheses derived from site investigations and literature, to investigate the pathways utilized for the transportation of heavy metals throughout the catchment.

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

Blue-green infrastructure have been more lucrative during the last 30 years, since urbanizationbrings more impervious surfaces that increases stormwater runoff volumes. Amongst thedifferent blue-green infrastructures there are e.g., constructed wetlands and swales. Blue-greeninfrastructure means more natural management of the stormwater, such as infiltration. Forinfiltration of water, the hydraulic conductivity is an important parameter, but also the abilityto remove dissolved pollutants. In literature, various studies of filter materials are only testedfor single dissolved pollutants, which might be a disadvantage as this does not represent fieldconditions where metals usually co-exist. Economic costs are also an important parameter,unfortunately not always targeted in research. In this thesis, the efficiency of five different material mixtures for removing typical dissolvedstormwater pollutants: chromium (Cr), copper (Cu), nickel (Ni), phosphorus (P), lead (Pb) andzinc (Zn) were studied. The mixtures were following: 1) crushed rock + soil (RO_SO) 2)crushed rock + soil + LECA 4/10 + biochar (RO_SO_BC_LC4). 3) crushed rock + soil + LECA10/20 + biochar (RO_SO_BC_LC10). 4) Soil (SO). 5) crushed rock + soil + biochar(RO_SO_BC). This study was a part of blue-green investments that is being made in Östersundmunicipality and the use of low-cost materials for stormwater treatment are examined. The study was made using batch equilibrium tests, to determine the sorption capacity fordifferent material mixtures, using dissolved metal- and P-solutions. The measured data werefitted to Freundlich, Langmuir, Temkin, Dubinin-Radushkevich and Redlich-Petersonisotherms. Economic feasibility has also been compared between the material mixtures.Results showed that SO had the best sorption capacity for all metals and P, with rankingPb > Cr > Cu > Ni > Zn for the metals. All material mixtures showed a removal efficiency of79-99%, at the lowest concentration (1mg/L) for the metals and 31-62% for the lowestconcentration of P-single solution (1mg/L). Using additional materials in the mixtures, such asbiochar, slightly improved the sorption capacities of Pb and P. Redlich-Peterson isothermsprovided the best fits to the data. An economic evaluation of the ingoing materials shows thatSO and RO_SO are undoubtedly the most feasible alternatives for removal of targeted metalsand P.

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.

Urban development leads to increased impermeable landscapes that interrupt the hydrological cycle by creating an impermeable barrier to the natural infiltration of precipitation. Precipitate, unable to infiltrate, flows over impermeable surfaces as sheet runoff, carrying the pollutants from the land with it; thus comprising the quality of the stormwater. The runoff is redirected (frequently untreated) to nearby waterways altering their water quality and quantity, thereby, adversely affecting receiving aquatic ecosystems. Suspended solids and elevated heavy metal concentrations in stormwater are the leading causes of water quality degradation in urban waterways in New Zealand. It is widely reported that vehicles and metal roofs are a major direct source of the key pollutants (total suspended solids (TSS) and heavy metals) in stormwater runoff; however, the contribution of atmospheric deposition, as an indirect source, in stormwater runoff is rarely considered. This is principally due to the many uncertainties and challenges with measuring and managing these pollutants in stormwater runoff. Therefore, a monitoring programme into the dynamics controlling atmospherically derived pollutant build-up and wash-off from urban surfaces was conducted. In particular, this research focused on the spatial and temporal variability of Cu, Zn, Pb, and TSS deposition in different land-use areas; the influence of pavement type on atmospherically-deposited pollutant loads in stormwater; and the contribution of wet deposition and dry deposition to the total deposition loads. Impermeable concrete boards (≈ 1 m2) were deployed for 11 months in different land-use areas (industrial, residential and airside) in Christchurch, New Zealand, to capture spatially distributed atmospheric deposition loads in runoff over varying meteorological conditions. Mixed-effect regression models were developed to explain the influence of different meteorological characteristics on pollutant build-up and wash-off dynamics. Next, impermeable asphalt, permeable asphalt, impermeable concrete, and permeable concrete boards were deployed for two months in a residential land-use area to determine the influence of pavement composition and roughness on pollutant loads in stormwater. Finally, wet deposition samples were analysed in an industrial land-use area for 8 months to monitor the contribution of wet deposition to atmospherically-deposited pollutant loads. All samples were analysed for total and dissolved Cu, Zn, Pb, and TSS. Pavement type: Results showed that both impermeable and permeable concrete were efficient at retaining Cu and Zn. Bitumen leaching from the impermeable asphalt was a significant source of Zn to runoff. However, bitumen leaching from the permeable asphalt did not contain elevated Zn loads. Infiltrate from the permeable asphalt provided little/no removal of Cu and Zn. Impermeable asphalt provided greater retention of TSS and Pb over impermeable concrete because its rougher surface entrapped more particulates. TSS and Pb loads were the lowest from the permeable pavements due to the pavers filtering out particulates. Spatial variability: Results showed that all three land-use areas exhibited similar patterns of varying metal and TSS loads, indicating that atmospherically-deposited metals and TSS had a homogenous distribution within the Christchurch airshed. This suggested that the pollutants originated from a similar source and that the surrounding land-use was not an important factor in determining atmospheric pollutant loads to stormwater runoff. Although, higher pollutant loads were found for the industrial area, this was attributed to local topographic conditions rather than land-use activity. Temporal variability: Results illustrated the importance of antecedent dry days on pollutant build-up. Peak rainfall intensity and rain duration had a significant relationship with TSS and Pb wash-off; rain depth had a significant relationship with Cu and Zn wash-off. This suggested that the pollutant speciation phase plays an important role in surface wash-off. Rain intensity and duration influenced particulate pollutants, whereas, rain depth influenced dissolved pollutants. Additionally, mixed-effect models could predict approximately 53-69% of the variation in airborne pollutant loads in runoff. Deposition pathways: Wet deposition was an important contributor of dissolved Zn to stormwater runoff. However, dry deposition was the greatest source of total Cu, Zn, and Pb loads in stormwater runoff. This is principally due to the low annual rainfall in Christchurch limiting pollutant removal via wet deposition unlike dry deposition, which is continually occurring. Understanding the dynamics of airborne pollutant deposition and their contribution to stormwater pollution could help stormwater managers in strategic decision-making processes such as choice of location and installation of different treatment systems.

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

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.

Validerat; 20150715 (global_studentproject_submitter)

Development of cities, new buildings and other impervious surfaces entails increased stormwater flows, volumes and pollutant loads. Heavy metals, nutrients, sediments and salt are common pollutants in stormwater. The conventional way to managestormwater, which is by discharge to the receiving water body via asewage network, will not be sufficient for mitigating high flows, flood risks and pollution export. Thus,Low Impact Development (LID) stormwater facilities, such as stormwater biofilters, are built in an increasing rate in Swedenand worldwide.The main function of a stormwater biofilter is water quality treatment, which is achieved when stormwater percolates through a vegetated filter media. Sometimes a pre-treatment facility is installed before the biofilter to reduce thesedimentload on the biofilter and extend its life-length. However, there are knowledge gaps regarding pollutant removal in biofilters and the role of associated pre-treatment facilities. In this study the impact of a pre-treatmentfacility, calcium carbonateas amendment in the filter media and vegetation wasinvestigated regardingtreatment of heavy metals (Cd(cadmium),Cu(copper), Pb (lead)and Zn (zinc)), phosphorus and total suspended solids. To do this, influent and effluent stormwater samples from an existing biofilter in Sundsvall were analysed and evaluated regarding removal performance of the above-mentionedpollutants. In general, the stormwaterbiofilter facility (including pre-treatment) removed total metals well while the removal of the dissolved fraction showed higher variations. Influent concentrations of TP were always higher than effluentconcentrations. Leaching of phosphate repeatedly occurred from the filter sections.The mean removalof TSS was high (96.9%). CaCO3as amendmentin the filter material had a beneficial effect on the overall metal removal of the stormwater facility. Although leaching of phosphate occurred from all filter sections, the leaching was lowest from the section with CaCO3, indicating possible benefits of CaCO3as amendment. CaCO3 did not seem to affect the mean total phosphorusremoval significantly.Removal of total metals seemed to be improved by vegetation, but the removal of dissolved metals, total phosphorusand phosphate did not seem to be enhanced by vegetation. The filter section with vegetation and without CaCO3 amendment contributed with the highest effluent concentrations of total phosphorusand phosphate (leaching), considering that vegetation released more phosphate that it captured. The main treatment of the stormwater pollutants occurred within the biofilter and both positive and negative removal of all pollutants was observed by the pre-treatment facility. The result showed that the pre-treatment facility was most beneficial for removal of dissolved metals.
Utvecklingen av städer, nya byggnader och andra hårdgjorda ytor ökar både mängden dagvatten och föroreningshalterna. Vanligt förekommande föroreningar i dagvatten är tungmetaller, näringsämnen, sediment och salt.Det traditionella sättet att hantera dagvatten är genom avledning via avloppsnätet till närliggande recipient, men med den förändrade kvalitén och kvantitet på dagvatten blir kapaciteten i det befintliga ledningsnätet otillräckligtför de ökadeflödenaoch föroreningsinnehållet.Därför byggs bland annat dagvattenbiofilter, som är en typ av Low Impact Development (LID), i en ökande takt i Sverigeoch globalt. Huvudsyftet med dagvattenbiofilter är dagvattenrening, vilket uppnås när dagvattnet filtreras genom en filterbädd med växter. För att minska (sediment)belastningenoch förlänga livslängden på biofiltret kan ibland en förbehandlingsanläggning placeras i före biofiltret. Dock finns det fortfarande kunskapsluckor om reningspotentialen i biofilter och betydelsen av en förbehandlingsanläggning. I den här studien undersöktes betydelsen av en förbehandlingsanläggning, kalciumkarbonat som tillsatsi filter materialet och växter på biofiltret för reningen av tungmetaller (Cd (kadmium), Cu (koppar),Pb(bly)ochZn(zink)), fosfor och totalt suspenderat material. För att undersöka detta analyserades och utvärderades dagvattenprover på inkommande och utgående vattenfrån ett biofilter i Sundsvall, med avseende på reningsprestation av ovan nämnda föroreningar. Resultatet visade att biofiltret (med förbehandlingsanläggningen inkluderad), renade totala metaller bra medanreningen av lösta metaller varierade mer. Inkommande koncentrationer av totalfosforvar alltid högre än utgåendekoncentrationeroch fosfat lakades kontinuerligt ut från filtersektionerna. Den genomsnittliga reningen av TSS var hög (96,9%).CaCO3 som tillsats i filtermaterialet hade en positiv effekt på reningen av totala och lösta metaller i biofiltret. Fosfat lakades ut från alla filtersektioner,men urlakningen var lägst från filtersektionen med CaCO3, vilket tyder på möjliga positiva effekterdet som tillsats i filtermaterialet.CaCO3 verkade inte öka genomsnittliga reningen av totalfosfor signifikant. Vegetationenverkade öka reningen av totala metallermen inte reningen av lösta metaller, totalfosfor eller fosfat. Filtersektionen med vegetation men utan CaCO3genererade de högstautgående koncentrationernaav totalfosfor och fosfat (urlakning), vilket tyder på att vegetation avgav mer fosfor än den tog upp. Den dominerande reningenav dagvattenföroreningarnaskedde inuti biofiltret och både högre och lägre koncentrationer av samtliga föroreningar observerades efter förbehandlingsanläggningen.Resultatetvisade attförbehandlingsanläggningen var mest effektiv för reningen av lösta metaller.

The management of stormwater runoff is a particular challenge for communities in karst regions. Most guidelines for compliance with regulations for stormwater monitoring and mapping pertain to non-karst environments. It can be argued that effective stormwater management is even more essential to karst regions because stormwater receives little or no natural filtration as it is transferred through conduits in the subsurface and the buildup of pollutants underneath can be detrimental to community and environmental health if not effectively mitigated. Because of the limited resources available to determine how stormwater runoff carries potential pollutants across the surface before being transferred to the karst subsurface and then reentering back on the surface across the landscape, this study aims to use geographic information systems (GIS) to investigate this problem. The objectives of this study are twofold. The first objective is to understand the transport mechanisms for stormwater runoff and how the movement through karst systems differs from non-karst systems, especially in regards to the surface and subsurface interactions. The second objective is to develop a general procedure for predicting stormwater runoff pathways in karst regions using GIS technologies and spatial analysis techniques – including identifying which data and techniques are essential to analyze surface and subsurface processes - to improve stormwater monitoring effectiveness. The premise of this study is broken down into a conceptual model with three significant components: Surface Input (stormwater runoff on surface), Subsurface Transport (stormwater transport through subsurface), and Output to Surface (output of stormwater to the surface via springs). The first component utilizes Hydrological Analysis and Network Analysis techniques to determine stormwater runoff pathways from potential point-source pollutant sites across surface to injection points where runoff enters subsurface. The second component uses Spatial Interpolation Techniques and Hydrological Analysis to predict subsurface accumulation areas that collect runoff from injection points and subsurface conduit pathways to output locations. The third and final component examines the output of the runoff back to the surface and identifies the locations where stormwater runoff can be sampled. The analyses of the Surface Input component proved to be effective in predicting the behavior of stormwater runoff between pollutant sites and their corresponding injection points. The analyses of the Subsurface Transport captured the overall patterns in the inferred dye tracing pathways that were used as the control dataset. The Output to Surface established the linkages among RCRA sites, their corresponding injection points and ultimately their output springs. These findings are very useful in developing informed stormwater sampling strategies and plans. In future investigations, these results could be verified with stormwater sampling and additional dye tracings and can be improved in two ways: more complete datasets of all stormwater features in the area – especially springs and drywells, and a more extensive and equally distributed dataset for groundwater depths across the study area to create a more accurate interpolated potentiometric surface.

Stormwater provides a direct link between urban infrastructure and the urbanised natural environment. In particular, highway drainage presents a high risk of pollution when compared to other urban land use areas (Ellis et al., 2012); introducing heavy metals, suspended solids and hydrocarbons to urban waterways. This research investigated runoff from the R300 highway, located in the greater Cape Town area. The City of Cape Town Management of Urban Stormwater Impacts Policy requires the treatment and attenuation of stormwater from developments within the city, and proposes Sustainable Drainage Systems (SuDS) as a means to achieve this (CSRM, 2009b). SuDS are structural and process controls that attenuate surface drainage, improve runoff water quality, provide amenity and deliver ecosystem services. This study characterized the R300 runoff through a sampling program and modelling exercise in order to provide an indication of the ability of SuDS to manage highway runoff in South Africa. Sediment and runoff samples were collected from the road surface and an undeveloped parcel of land adjacent to the highway. The sampling results showed that heavy metals, suspended solids and phosphorus are present in significantly greater concentrations in road runoff compared to rainwater from the same area. The concentration of aluminium, copper, lead, zinc and phosphorus exceed the Department of Water and Sanitation's water quality guidelines for aquatic ecosystems in excess of 1000%. The concentration of heavy metals, phosphorus and fats, oils and greases was significantly greater in road sediment compared to sediment from the surrounding area. Barring copper, all contaminant concentrations in the road surface sediment are less than the maximum concentration required to protect ecosystem health. The R300 rainfall-runoff response was modelled in PCSWMM to evaluate the performance of SuDS such as infiltration trenches, bioretention areas and swales for managing highway runoff in terms of quantity and quality. The modelling exercise showed SuDS to be a viable means to attain the City of Cape Town's stormwater objectives, provided that SuDS are implemented in treatment trains along the entire road length.

Although wood floor production does not use water in the production process, water consumptionis related to cleaning and washing of floor and machineries in different steps of the process line,which generate a number of small flows that are highly polluted.Besides this, the industry has a need to store large amounts of wood outside to be able to havecontinuity in the production. This takes up a lot of space outdoors and once it rains the water thathas been in contact with wood, oil and metals forms stormwater, which transports pollutants.Stormwater has for a long time not been seen as a problem and has often been discharged intorecipient water bodies without any treatment. During cold seasons, this also involves snowmelt thatcan transport high concentrations of different pollutants.This report describes the composition of process- and stormwater from a wood floor industry inNybro, Sweden regarding parameters such as COD, phenol, tannin and lignin. The concentrationsof phenols in the stormwater were found in a range considered toxic to marine life.Regarding the process water, high values was found for COD (Chemical Oxygen Demand) and forother substances and elements potentially toxic (e.g. formaldehyde, wood resins, detergents andmetals). If these waters are directly released to a sewage treatment plant without any pre-treatmentprocess it can disturb the plant treatment efficiency; if released to a recipient water body, it cancause oxygen deficiency and consequently, death to marine life.The possibility of reducing the levels of pollutants through the use of electrocoagulation has beenexamined in this study. This has been done both for process water and stormwater from the woodfloor industry. A 250 ml batch unit for electrocoagulation EC was setup with iron (Fe) andaluminium (Al) electrodes for treating process water and stormwater. The results show that the ECprocess can reduce COD concentration from stormwater at least 70%. On the other hand, lessefficiency of EC for treating process water was observed.A method for simulating a snowmelt period in lab scale was also developed. Snow collected from awood floor industry was melted according to real temperature and the quality of these samples hasthen been compared to on-site samples of stormwater

Development of an integrated approach for industrial wastewater and stormwater management in the wood-industry sector

Market gardening is commonly characterised by intensive cultivation, high inputs of both organic and inorganic fertilisers, chemical over/misuse, frequent irrigation, and a low degree of soil cover. While market gardening is readily perceived to be detrimental to waterways, there is remarkably little data to quantify the impacts. Soil and nutrient loss in stormwater runoff varies with soil type, climate and production systems. Therefore local data are needed to determine the impact of market gardening on the Hawkesbury-Nepean. This should lead to a better understanding of how land management influences runoff quantity and quality so that practices can be improved. Objectives of this research were to : quantify sediment, N and P loss and assess the implications for waterways; relate sediment, N and P losses to specific land management practices and assess their impacts on profitability; and, reflect on this research in terms of extension and adoption of better land management. An 8.8 ha property with 6.6 ha of market garden was used as a case study in the Hawkesbury-Nepean Catchment. Soil samples were collected at the beginning and end of the study. Sediment core samples were collected from the drainage channel. A rainfall simulator was used to compare runoff volume from green manure and bare fallow beds. The research produced several recommendations for the extension and adoption of improved land management. In order to reduce sediment, N and P losses in stormwater, the primary focus should be on improving soil and nutrient management, in particular matching fertiliser inputs more closely to nutrient requirements. The secondary focus should be on utilising structural measures, in particular farm dams, to prevent pollutants from entering waterways. The outcome should be decreased costs to the farmer and decreased impacts on waterways. The use of N-fixing green manure to decrease the use of poultry manure should be explored.
Master of Science (Hons)

Increased urbanization leads to more impermeable surfaces.Togther with climate changs with more intensive precipitation, more frequent urban floodings should be expected in the near future. As undreground convey systems have proven to be inadeqate, leading to several combined sewage overflows each year, new innovative stormwater management devices are relevant and also getting more recongnition.Raingardens, a planted depression, work as local stormwater management and allows water to infiltrate into the ground. A raingarden is planned on The Bryggen in Bergen, Norway. The Bryggen has struggled with lowering of the groundwater table, causing settling of overlaying buildings and increased decomposion of underlayning protected archaeological remains.The raingarden will be fed with stormwater from the catchment above The Bryggen.Microorganisms in the ground are responsible for decay of the archaeological remains, it was therefore importante to characterize the stormwater and indetify potential treaths to the archaological remains.It was found that stromwater from the impervious surfaces at The Bryggen catchment varies withlocation, surface use and within rain events. Different roofing material and traffic volume have differenteffects on pollutant distribution and concentration. The road Ovregaten with the most traffic (5001\--10 000 vehicles pr day) had the highest pollution levels for 8parameters (TSS, Conductivity, total P, PO^4-P, Cu, Ni Zn and Cu), while the smaller road Koren Wibergsplass had the highest pollution levelon one parameter (Pb).The roof surfaces had signigicantly lower pollutant levels, but does notachieve insignificant pollution level for recieving waters according the The Climate and Pollution Directorate in Norway. An estimated value for monthly TSS was 654 kg.The catchment had a minimum volume percent of particles with diameter below 1.2 micro m at 70% for S2, 10% for S6, while S3 and S4 had a maximum at 15% and 30% respectivley. Comparing filtrated and unfiltrated heavy metal samples for Overgaten it was shown that mimimum 65% of the metals was particle bound, while a value of 75% particle bound metals were more common.Through litterature review of pollutant retension in raingardens, it is estimated thatthe planned raingarden, with its high content of organic material will be able to retainheavy metals concentrations from 55% to 99%. It is suggested that the stormwater from the large road is not utilized in feeding the groundwater, due to the high pollutant level. No clear answer regarding sulfates and dissolved oxygen level in the effluent of the raingarden was found.

Stormwater is water that originates from snow or rainfall and that cannot naturally infiltrate the soil. When stormwater flows from hard surfaces it can transport different pollutants to watercourses. By measuring turbidity continuously and using the relationship between turbidity and pollutants the pollutant levels can be estimated. The aim of this study was partly to investigate the relationship between turbidity and phosphorus, metals and PAHs in stormwater in three catchment areas. This study also aimed to investigate how the distribution between dissolved and particulate bound concentrations of phosphorus and metals varied during different rain courses and at different catchment areas. The study was carried out in Uppsala and included continuous measurement of turbidity in three stormwater wells in three catchment areas. Seven samples were also taken at different precipitation occasions in both stormwater and in Fyrisån. In Svartbäcken there was a strong relationship between turbidity and phosphorus and metals. In Librobäck there was an indication that there was a strong relationship between turbidity and some metals and PAH:s. There was no relationship between turbidity and pollutants in Luthagen. Based on these samples, it is difficult to draw any conclusions about why the connections differed for certain pollutants and catchment areas. Due to the fact that the number of measuring points was too few the continuous measurement could not be used to estimate variations in pollution levels. To be able to use the continuous measurement, a longer sampling period and different precipitation occasions is needed. The continuous measurements were used to get an idea of when the samples were taken during the stormwater flow. The results also showed that all pollutants were mostly particulate bound for samples taken at the beginning of a precipitation occasion and with some precipitation during the sampling. For samples that did not take place in connection with stormwater runoff events, the distribution varied for the pollutants in the study. It has not been possible to see a clear trend for how the distribution between dissolved and particulate bound pollutants has varied between different catchment areas.
Dagvatten är vatten som uppkommer vid regn eller vid snösmältning och som inte kan infiltrera naturligt i marken. När dagvattnet avrinner ytligt på marken kan det föra med sig föroreningar till recipienten. Genom att mäta turbiditet kontinuerligt och utnyttja eventuella samband med föroreningar kan föroreningshalter i dagvatten uppskattas. Studien hade två huvudsakliga syften varav det ena var att undersöka samband mellan turbiditet och fosfor, metaller samt PAH:er i dagvatten i tre avrinningsområden. Detta för att se om sambanden kunde användas för att med hjälp av kontinuerlig mätning av turbiditet uppskatta föroreningshalter vid avrinningsområdena. Det andra syftet var att undersöka hur fördelningen mellan lösta och partikulärt bundna andelar fosfor och metaller varierade under olika regnförlopp och vid olika avrinningsområden.  Studien utfördes i Uppsala och innefattade delvis kontinuerlig mätning av turbiditet i tre dagvattenbrunnar i tre avrinningsområden. Det gjordes även sju stickprovtagningar vid olika nederbördstillfällen i både dagvatten och i Fyrisån. I Svartbäcken visade resultaten att det fanns starka samband mellan turbiditet och fosfor och metaller. I Librobäck fanns det en indikation för starka samband mellan turbiditet och fosfor samt vissa metaller och PAH:er. I Luthagen fanns det dock inga samband mellan turbiditet och undersökta föroreningarna. Utifrån dessa prover var det svårt att dra några slutsatser kring varför sambanden skilde sig åt för vissa föroreningar och avrinningsområden. På grund av att antalet mätpunkter var för få kunde inte den kontinuerliga mätningen användas för att uppskatta variationer av föroreningshalter. För att kunna använda den kontinuerliga mätningen behövs en längre provtagningsperiod med fler provtagningar.  Resultatet visade även att den partikulärt bundna andelen dominerade för alla föroreningar vid de provtagningar som togs i början på ett nederbördstillfälle och vid viss nederbörd. Vid provtagningar som utfördes senare under nederbördstillfället varierade fördelningen för de olika föroreningarna. Det har inte varit möjligt att se en tydlig trend för hur fördelningen mellan lösta och partikulärt bundna föroreningar varierade mellan olika avrinningsområden.

Les bassins de retenue-décantation ont trois fonctions principales : stocker les eaux pluviales pour éviter les inondations, favoriser la décantation des polluants particulaires, éviter la remise en suspension et la remobilisation des polluants décantés vers l’aval. La conception et la gestion de telles installations nécessitent de connaître les caractéristiques hydrodynamiques, celles des sédiments et de pouvoir prédire les zones où les dépôts sont fortement contaminés. L’objectif principal de la thèse est d’identifier les zones où les teneurs en polluants sont élevées au niveau des sédiments des bassins de retenue-décantation. Le site d’étude est le bassin de rétention des eaux pluviales de Django Reinhardt (BDR), qui est un bassin sec à l’exutoire d’un bassin versant industriel. Ce bassin a fait l’objet de plusieurs études dans le cadre de de l'Observatoire de Terrain en Hydrologie Urbaine (OTHU).Dans un premier temps, les mesures de vitesses de surface par LSPIV (Large-Scale Particle Image Velocimetry) ont permis de mieux comprendre l’hydrodynamique au sein de l’ouvrage. Ces mesures ont été exploitées pour évaluer les modèles CFD (Computational Fluid Dynamics). C’est la première fois que cette technique de mesure est appliquée au cas des ouvrages de gestion des eaux pluviales. Les résultats montrent que les modèles CFD identifient la principale zone de recirculation qui favorise la décantation. Ces modèles évalués ont ensuite été employés pour simuler le transport de polluants particulaires, leur sédimentation et leur remise en suspension. L’exploitation des résultats de ces simulations a permis d’indiquer les points où les sédiments sont remis en suspension et transférés vers le bassin d’infiltration à l’aval et de prédire les zones d’accumulation en métaux. Les résultats obtenus montrent également que les teneurs en fer dans les sédiments sont fortement corrélées aux vitesses de chute. Le fer pourrait être un bon indicateur du niveau de contamination des sédiments en certains métaux lourds. Les résultats de cette thèse contribuent à améliorer les règles de conception des bassins de retenue-décantation des eaux pluviales et les stratégies de gestion des sédiments associés
Stormwater detention basins have three main functions: storing rainwater to prevent flooding, promoting settling of particulate pollutants, avoiding resuspension and remobilization of settled pollutants to the downstream. The design and the management of such facilities requires the knowledge of hydrodynamic and sediment characteristics, as well as the ability to predict areas where deposits are highly contaminated.The main objective of this PhD work is to identify the areas where pollutant levels in sediments are high in detention and settling basin. The studied site is the stormwater detention basin (Django Reinhardt basin or DRB), which is an extended and dry basin at the outlet of an industrial watershed. This basin has been the subject of numerous investigations within the framework of the Field Observatory for Urban Water Management (or observatoire de terrain en hydrologie urbaine - OTHU in French).First of all, the measurements of surface velocities by Large-Scale Particle Image Velocimetry (LSPIV) permits to better understand the hydrodynamic behaviour in the basin. These measurements were used to evaluate CFD (Computational Fluid Dynamics) models. This is the first time this measurement technique has been applied in the case of stormwater management facilities. The results show that CFD models identify the main recirculation zone that promotes settling. These evaluated models were then used to simulate the transport of particulate pollutants, including sedimentation and resuspension. The exploitation of these simulations results enables to (i) identify the preferential areas where resuspended contaminated sediments may be conveyed to the downstream infiltration basin and (ii) predict the accumulation zones of some metals. Results also demonstrate that iron contents in sediments are strongly correlated to settling velocities and can be considered as a good indicator of the level of heavy metals contamination of sediments. The results obtained in this thesis contribute to improve the design of stormwater detention and settling basins and the management of contaminated sediments

Stormwater runoff is one of the leading causes of water quality impairment in the U.S. Bioretention systems are ecologically engineered to treat stormwater pollution and offer exciting opportunities to provide local climate change resiliency by reducing peak runoff rates, and retaining/detaining storm volumes, yet implementation is outpacing our understanding of the underlying physical, biological, and chemical mechanisms involved in pollutant removal. Further, we do not know how performance will be affected by increases in precipitation, which are projected to occur in the northeastern U.S. as a result of climate change, or if these systems could act as a source or sink for greenhouse gas emissions. This research examines the design, construction, and development of monitoring methods for bioretention research, using the University of Vermont (UVM) Bioretention Laboratory as a case study. In addition, this research evaluates mobilization patterns and pollutant loads from road surfaces during the "first flush" of runoff, or the earlier part of a storm event. Finally, this research analyzes the comparative pollutant removal performance of bioretention systems on a treatment by treatment basis. At the UVM Bioretention Laboratory, eight lined bioretention cells were constructed with monitoring infrastructure installed at the entrance and at the subterranean effluent. A conventional, sand and compost based, bioretention soil media was compared to a proprietary media engineered to remove phosphorus, called Sorbtive Media™, under simulated increases in precipitation. Two drought tolerant vegetation mixes, native to the northeast, were compared for sediment and nutrient retention. Each treatment was sampled for soil gas emissions to determine if it was a source or a sink. The monitoring infrastructure designs used in this research allowed for the effective characterization of pollutant mass loads entering and exiting bioretention. Cumulative mass loads from stormwater were found to be highest for total suspended solids, followed by total Kjeldahl nitrogen, nitrate, non-labile phosphorus and soluble reactive phosphorus, in descending order by mass. Total suspended solids, total Kjeldahl nitrogen, and non-labile phosphorus mass were well retained by all bioretention treatments. However, the compost amendment in the conventional soil media was found to release labile nitrogen and phosphorus, far surpassing the mass loads in stormwater. When compared with conventional media, Sorbtive Media™ was highly effective at removing labile phosphorus and was also found to enhance nitrate removal. Systems containing deep-rooted vegetation (Panicum virgatum) were found to be particularly effective at retaining both labile and non-labile constituents. Overall, none of the bioretention treatments were found to be a significant source of N2O and were small sinks for CH4 in most treatments.

Stormwater runoff may contain high levels of pollutants and is regulated by the Federal National Pollution Discharge Elimination System (NPDES). Stormwater bioretention (BR) systems are often used to satisfy these regulations. BR systems collect accumulated runoff that leaches into groundwater. A greenhouse study evaluated nutrient and metal removal among plant species that are typically found growing in BR systems. A field demonstration study assessed citric acid enhanced metal bioaccumulation potential under typical BR system conditions. The greenhouse experiment examined pollutant retention, and bioaccumulation potential for six plant species undergoing three hydraulic and pollutant loads. Results verified there was 98% recovery of total phosphorous over the study period. Biomass increased with higher hydraulic and pollutant loads for all species. Phragmites australis, Carex praegracilis, and Carex microptera took up significantly more total phosphorous and nitrogen mass into shoots than Typha latifolia, Scirpus valid us, and Scirpus acutus. This study also found that 89% of applied metals were removed within the top 27 em of soil in all treatments. Similar results were found regarding copper, lead, and zinc concentrations and bioaccumulation. Carex praegracilis, and Carex microptera exhibited higher metal distribution in plant tissue and exfiltrate, and lower distribution in the soil media than the other species. This indicated species differences in biological and chemical processes taking place within the simulated BRsystems. The field experiment investigated citric acid enhanced metal bioaccumulation potential among three different plant species under representative BR conditions. Citric acid significantly increased metal concentrations in the soil pore water for the planted treatments, but this did not result in increased metal uptake into plant tissue. However, notable differences were found among species, where Carex microptera accumulated more AI, Cr, Cu, and Fe in the above ground tissue than Helianthus maximiliani and Typha /atifolia (except for Cu in Helianthus). These results provide greater insight into the biological and chemical process that affect transport, uptake and translocation of nutrients and metals, and confirm the importance of species selection in BR systems to optimize nutrient and metal retention and recovery from stormwater runoff to minimize subsequent groundwater pollutant loading.

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.

This thesis project monitors the quantity and quality of stormwater entering and leaving a bioretention system in Coralville, Iowa. Bioretention is among many engineered solutions designed to provide treatment for runoff that might otherwise be drained directly to a body of water. Increased quantities of stormwater can impact stream morphology, degrade aesthetics, increase flood frequency, peak flow, and peak duration; as well as increased sedimentation and sediment transport. Decreases in water quality can impair fish or other aquatic populations, and increase the treatment requirements for downstream intakes. The number of communities, presently 47, affected by stormwater control ordinances increases as the Environmental Protection Agency continues to require smaller Municipal Storm Sewer Systems to adhere to National Pollutant Discharge Elimination System permits. The City of Coralville is setting an example by using infiltration practices to treat runoff from a 4-lane divided thoroughfare. Preliminary monitoring shows that the system in Coralville provides an average reduction in effluent temperature g of 3.7°C, an average reduction in peak flow of 2 cfs, and an average peak delay of 45 minutes. The project provides infiltrative treatment for the water quality volume and the empirical curve number for the project is 77.4. The urban runoff to the project is within literature values and the pollutant concentrations in the project effluent are below legal limits.

Long-term hydrologic and nonpoint source (NPS) pollutant response is quantified for four headwater basins of the Occoquan River in northern Virginia using 24 years of observed rainfall, basin discharge, water chemistry, and derived land use/land cover (LULC) data. Long-term summaries document that several hydrologic and NPS pollutant delivery characteristics in the urbanizing Cub Run basin are significantly different from adjacent non-urban basins. Higher annual NPS fluxes of total suspended solids (TSS), phosphorus (P), and nitrogen (N) in Cub Run are identified with periods of increased soil disturbance from urban land development and significantly increased storm volumes resulting from higher mean impervious cover. Long-term summaries of nutrient flux are consistent with literature documenting increased ratios of particulate to soluble nutrients with increased discharge. Storm fluxes of NPS particulate P, soluble P, particulate N, and soluble N make up 92, 67, 89, and 50 percent, respectively, of total NPS nutrient fluxes from all headwater basins, with between 88 and 98 percent of mean annual TSS fluxes delivered by storm flow. Higher sediment and nutrient fluxes observed in Cub Run basin during the summer and fall growing season after 1983 demonstrate the impact of replacing vegetated cover with urban impervious surface (IS). Annual regression models indicate that mean IS above 10 percent and precipitation are significantly associated with total basin discharge (r2=0.65). The positive association of annual storm soluble phosphorus flux with cumulative mean IS suggests the need for continued evaluation of urban NPS soluble phosphorus strategies. Urban soil disturbance is indicated by measuring the annual change in mean IS (delta IS). Regression models show that urban soil disturbance is a significant source of TSS flux in all seasons. Long-term total soluble phosphorus and nitrogen fluxes are significantly and positively associated with precipitation, delta IS, and agricultural land use (r2=0.50 and 0.58, respectively). The significant impact of urbanization on hydrologic and NPS pollutant flux, especially during the growing season, is a major finding of this study.
Ph. D.

The Oak Ridge National Laboratory, Tennessee, was the site for a number of US Government projects during the 1940s and 1950s including the development of thermonuclear weapons. Chemical processes conducted at the site as part of these projects resulted in contamination of certain building areas at the ORNL. The purpose of this study is to develop a hydraulic-hydrologic computer model via XPSWMM to determine surface water flow rates and water stages within the drainage system during rainfall events and introduce a conservative contaminant into the system to trace peak concentrations of contaminants. The model was calibrated by simulating actual rainfall events over the area of interest. The model results were compared to that of Outfall 211’s monitored data. Trial 1 was most successful, where the cumulative flow rates produced by the model and the monitored data varied only by 0.5 cfs. A sensitivity analysis was completed by varying Manning’s coefficient and infiltration parameters within the area of interest. The sensitivity analysis concluded that the model was responsive to the variations presented; however, only minor differences were determined for the selected range of parameters, indicating robustness of model predictions. A hypothetical conservative contaminant was entered into the system as constant and varied timeseries. The resulting pollutographs produced by XPSWMM aid in the assessment for potential mobilization of contaminants and provide insight to where peak concentrations and loads occur under present conditions. Probability exceedance and probability distribution methods were used to analyze the timeseries of flow and pollutant concentrations collected during this study. Probability exceedance curves determined the percentage of time flooding occurred within the system under various conditions. The flow rates and concentrations produced by the transport analysis were best described by the Generalized Extreme Value, while the loading rates were best described by Log-logistic distribution.

Many different stormwater control measures (SCMs) can be implemented in order to mitigate issues with polluted stormwater flows into receiving water bodies.  The treatment function of  SCMs is commonly based on the removal of particles by sedimentation, thereby also removing pollutants associated with particles. In recent years, more attention has been given to characterizing and understanding of different particle size fractions and their association with pollutants commonly found in stormwater. It has become increasingly clear that the smaller sized particles are very important pollutant transporters and should be considered when designing and implementing SCMs. However, the settling velocities for smaller sized particles are very low and may not be effectively removed in existing SCMs. One treatment process with a proven ability to enhance sedimentation is coagulation/flocculation, widespread in water and wastewater treatment, but with very few accounts of it being used in a stormwater context. This thesis aims to investigate the treatability of stormwater with a coagulation/flocculation process. This includes the determination of operating conditions, the dominating coagulation mechanism and the reduction efficiency of stormwater related pollutants. The objectives of the thesis were achieved in laboratory tests treating stormwater in a jar-testing procedure. An initial screening of primary coagulants and flocculant aids was conducted using an urban snowmelt mixture. Five of the chemicals were then selected for an extended testing regime which was setup up to determine the operating conditions where maximal turbidity reduction was attained by measuring the pH, conductivity, alkalinity and zeta-potential over the tested doses for each coagulant. Criteria used for chemical selection included high turbidity reduction, low dose requirement and low pH/alkalinity impacts. Charge reversal was observed at positive zeta-potential indicating that the dominating coagulation mechanism was charge neutralization. The content of turbidity/total suspended solids, total organic carbon, total metals and hydrocarbons by >90%. Dissolved copper was reduced by 40% on average, and the reduction rates for dissolved zinc were varying with up to a 300% increase, presumably due to changes in pH, leading to a higher mobility. Changes in the particle size distribution after coagulation/flocculation as compared to sedimentation indicated an effect on the size fraction corresponding to smaller particles. The performance of the coagulation/flocculation process was also tested on road runoff collected from a central road in Luleå with a high traffic intensity. Two coagulants were tested, iron chloride and pre-hydrolyzed aluminum chloride. Reduction rates for the total metal fraction were >90% on average for both coagulants, but for the dissolved metal fractions differences could be observed between the coagulants with the iron chloride resulting in higher reductions for dissolved chrome (57% compared to 34%) and copper (47% compared to 30%). Both products increased the dissolved fractions of nickel and zinc due to lower final pH.

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.

Monitoring of a regional stormwater management facility, located on the Virginia Tech campus in Blacksburg VA, was conducted in order to assess its efficacy in reducing nonpoint source pollutant losses downstream. The facility design includes both an upper water quality (wet) pond and a lower 100-yr-event quantity (dry) pond. These on-stream ponds capture both baseflow and storm runoff from the southern portion of the Virginia Tech campus and surrounding lands, and release the water back to the unnamed stream shortly above its conjunction with Stroubles Creek, a tributary of the New River. Monitoring sites for flow measurement, water quality sampling, and biotic assessments (habitat evaluation and rapid bioassessment of benthic macroinvertebrates) were located above and below each of the ponds.

Both grab samples and automated samples were collected at these stations. Between 1997 and 1999, water quality grab samples included 35 baseflow samples and 22 stormflow samples. The grab samples were analyzed for concentrations of total suspended solids (TSS), metals, bacteria, and nutrients as well as temperature, pH, dissolved oxygen, conductivity, total organic carbon (TOC), and chemical oxygen demand (COD). Automated flow-weighted sampling was initiated in February of 1999 and results are reported through the end of October 1999. Thirty-three storms in 1999 were monitored for flow and various water quality parameters (TSS, TOC, COD, and nutrients). Pollutant loads and pollutant removal estimates were calculated with regard to the wet pond, dry pond, and the combined facility. Two types of pollutant removal efficiencies were calculated: (1) the EMC efficiency, based on pollutant concentrations from individual storms; and (2) the SOL efficiency, based on pollutant loads, to estimate long-term performance over the study period. Benthic macroinvertebrate sampling and habitat assessment were performed in both 1997 and 1999. In addition, a preliminary investigation of pond characteristics was conducted, including measurements of water quality and composition, sediment deposition and composition, and residence time.

As a system, the stormwater management facility appears to have minimum impact on improving the downstream water quality. Pollutant concentrations and loads both appear to increase downstream of the facility as compared to upstream, during both storm event and baseflow periods. Monitoring results of the benthic assemblages showed evidence of moderate to high impairment at all sampling locations, and habitat assessments showed evidence of high sedimentation levels within the stream, even after installation of the stormwater management facility. Total suspended solids (TSS) concentration removal efficiency was 10% for the combined wet pond and dry pond system, much lower than the 80 to 90% TSS removal expected for properly functioning stormwater management facilities (Hartigan, 1989). There is some evidence of sedimentation within the ponds because of a slight reduction in sediment-bound constituent export, but the dissolved nutrient constituents had either very low and most often negative (indicating pollutant export) removal efficiencies. Concentrations of metals measured in the stream often exceeded their respective acute and chronic water quality criteria at all sampling locations.

Pollutant removal efficiencies measured in the wet pond are atypical of those reported in the literature (Schueler, 1993). Insufficient residence time (two days compared to the optimal two weeks), and wet pond embankment failure are likely the principal causes of the wet pond's inadequate performance and thus, the inadequate performance of the overall facility. TSS removal efficiencies were low in the wet pond (19% for concentrations and 33% for loads) compared to the 80 to 90% expected for similar ponds. Nevertheless, the wet pond reduced the concentrations of several pollutants typically associated with TSS and not likely to be associated with the fill material for the wet pond embankment. Zinc concentrations in sediment cores were highest near the pond inlet, where the majority of sedimentation occurs. During storm events, the following results were noted. Copper and zinc concentrations in 1998 were lower at the pond outlet as compared to the pond inlet, and TOC concentrations and loads were also reduced by the wet pond (13% for concentrations and 12% for loads). However, sedimentation is also expected to remove phosphorusl, and wet pond phosphorus loads were only reduced by 10% and 3% for orthophosphorus and total phosphorus, respectively.

Because the wet pond is undersized with respect to the watershed it serves (surface area less than 1% of the watershed area (0.87 ha), as compared to the 3% ratio often recommended for optimal pollutant removal (Athanas, 1988)), higher removal efficiencies were found during baseflow periods. The greatest reductions in baseflow concentrations were for ammonia (67%), nitrate (57%), total nitrogen (54%), and COD (45%). However, the residence time of two days appears to be insufficient to reduce fecal coliform concentrations in the stream, and over 40% of the fecal coliform samples collected exceeded the water quality standard for contact recreation (DEQ-WQS, 1997). Furthermore, the wet pond did not appear to reduce TSS or TOC during baseflow periods. Export of TSS (-29% EMC efficiency) and TOC (-44% EMC efficiency) from the wet pond during baseflow periods is likely due to the wet pond embankment failure as well as pond eutrophication. Eutrophication processes are favored by the water temperature increase as flow passes through the shallow wet pond. The wet pond increased downstream temperatures by approximately 8°C above inflow temperatures during the summer, and to levels above 21°C which cannot be tolerated by sensitive coldwater species (Schueler, 1987).

The dry pond did not remove dissolved nutrient constituents or other pollutants during baseflow periods, but there is some evidence of sedimentation within the dry pond during storm events. During storm events, the dry pond was effective in removing TSS, with a concentration removal efficiency of 69% (EMC efficiency) and loading removal efficiency of 43% (SOL Efficiency). Removal of TKN and total phosphorus (36% and 37% respectively for concentrations) within the dry pond is further evidence of sedimentation within the dry pond.

The wet pond embankment was built in 1997, and monitoring occurred during a potential stabilization period when evidence of water quality benefits are slow to appear, especially with respect to downstream habitat and aquatic communities. Some benefits which could have been observed more immediately may have been negated or masked by the progressive erosion of the wet pond embankment as a result of a design flaw. Further complicating the results is the appearance; based on observations of extended drawdown time and results from a water budget analysis in the wet pond (where inflow substantially exceeds inflow); that groundwater interacts with the pond in a complicated fashion, possibly including both recharge and discharge.

To fully understand the impact of the stormwater management facility on the water quantity and quality within this tributary of Stroubles Creek, monitoring efforts should continue after the wet pond embankment is repaired and is fully operational. If biotic community improvement is desired, the stabilization period could be defined by the time necessary to flush out accumulated sediment within the channel. Monitoring efforts should also expand to include the investigation of the groundwater regime and water level fluctuations within the wet pond. Further measurements of pollutant removal processes and influences upon those processes within the wet pond should also be considered. Last, the influence of the stormwater management facility on downstream flow regimes should be investigated to assess the adequacy of its performance with regard to flow control and prevention of stream channel degradation.
Master of Science

Det vatten som avrinner från hårdgjorda ytor, så kallat dagvatten, innehåller ofta en mängd olika föroreningar, så som tungmetaller och näringsämnen, som kan göra stor skada om vattnet inte renas innan det når recipienten. Ett vanligt sätt att rena detta vatten är genom öppna system, som dammar och våtmarker, eftersom de fungerar både som flödesutjämnare och som sedimentationsmagasin. I Steningedalen, Märsta, finns en dagvattenanläggning med dammar och översilningsytor, vars syfte är att rena dagvatten från ett avrinningsområde på ca 7200 ha. Vattnet leds till dammarna via en dagvattentunnel vars primära syfte var att leda vattnet förbi Märsta centrum. Tunneln är ca 3100 m lång, sprängd och delvis i betong, och har ett skibord installerat i tunnelmynningen med syfte att skapa ett sedimentationsmagasin samt att vid höga flöden leda vattnet förbi dammarna direkt till Märstaån. I denna studie har reningseffekten av denna dagvattentunnel utretts. Detta har gjorts genom provtagning av vattnet i två punkter i tunneln, den ena belägen ca 1 km uppströms tunnelmynningen och den andra i tunnelmynningen. Analyser med avseende på tungmetallerna bly, kadmium, krom, koppar, nickel och zink samt näringsämnet fosfor har därefter genomförts. Även halten suspenderat material och vattnets partikelstorleksfördelning har undersökts. För att komplettera vattenanalyserna har även tungmetall- och fosforhalten i sedimenten vid provpunkterna analyserats och sedimentmäktigheten mätts. Resultaten av vatten- och sedimentprovtagningen visar bland annat att halterna av tungmetaller i vattnet generellt är relativt höga. Speciellt zink återfinns i höga halter både i vattnet och i sedimenten och överskrider det av Naturvårdsverket uppsatta gränsvärdet för lösta halter i vatten. Vidare är fosforhalterna, enligt Naturvårdsverkets klassning för sjöar och vattendrag, extremt höga vid högt flöde och höga vid lågt flöde i tunneln.  Resultaten av filtreringsanalyserna visar på att partikelstorleken i vattnet är generellt mycket liten, vilket innebär att andelen partiklar som är stora nog att sedimentera också är mycket liten. Sedimentmäktigheten är dock högre i slutet av tunneln, vilket visar att sedimentationen ökar med ett minskat avstånd till tunnelmynningen. Detta beror sannolikt på att det installerade dämmet leder till en minskad vattenhastighet genom en ökning i tvärsnittsarea, vilket i sin tur leder till förbättrade förutsättningar för sedimentation. Resultaten visar vidare att halterna av tungmetaller och fosfor i dagvattnet inte skiljer sig avsevärt mellan provpunkterna vid lågt flöde i tunneln. Vid högt flöde är halten av tungmetaller och fosfor dock lägre vid tunnelmynningen jämfört med den övre provtagningspunkten, vilket tyder på att det sker en viss avskiljning i tunneln, sannolikt genom sedimentation av partikelbundna föroreningar. Därmed dras slutsatsen att tunnelns senare del uppvisar en god avskiljning av föroreningar vid ett relativt högt flöde, men att avskiljningseffekten minskar vid lägre flöden, vilket kan förklaras genom att partiklarna i vattnet generellt är mycket små men att både mängden partiklar och partikelstorleksfördelningen ökar vid högre flöden.
Stormwater often contains a variety of pollutants such as heavy metals and nutrients that can cause great damage if the water is not treated before it reaches the recipient. A common way to decontaminate this water is through open systems such as ponds and wetlands since they both act as a sedimentation tank and also create a more steady flow. In Steningedalen, Märsta, there is a constructed wetland system designed to clean stormwater from a catchment of about 7200 ha. The water is channeled to the ponds via a stormwater tunnel whose primary purpose was to carry water past the center of Märsta village. The tunnel is about 3100 m long, partially in concrete, and has a weir installed in the end of the tunnel. The purpose of the weir is partly to create a sedimentation basin and partly to channel water past the wetland system when high flows occur. In this study, the treatment effect of this stormwater tunnel is investigated. This has been carried out by sampling the water at two points, one about 1 km away from the end of the tunnel, and the other at the end of the tunnel, with subsequent analysis for the heavy metals lead, copper, cadmium, chrome, nickel and zinc as well as the nutrient phosphorus. Also, the concentration of suspended matter and the particle size distribution of the stormwater has been investigated. To supplement the water analysis, heavy metals and phosphorus in the sediments were analysed and thickness of the sediment was also measured. The result of the water and sediment sampling shows that the levels of heavy metals in the water are generally relatively high. Zinc in particular, is found at high concentrations both in water and in sediments and exceeds the Environmental Protection Agency’s limit. Phosphorus levels are also, according to the Environmental Protection Agency's classification of lakes and streams, extremely high at high flow rates and high at low flow rates in the tunnel. The results also show that the concentrations of heavy metals and phosphorus in surface waters do not differ significantly between the sampling points at low flow rates in the tunnel. At high flow rates, however, a reduced level of both heavy metals and phosphorus was detected in the end of the tunnel, which indicates that the level of these pollutants decreases with distance from the inlet due to sedimentation in the tunnel. Sediment thickness is greater at the end of the tunnel, which indicates that sedimentation increases towards the outlet of the tunnel which most likely is due to fact that the installed weir slows down the flow rates and creates a sedimentation basin. However, the results of the particle size distribution analysis show that the fraction of particles large enough to settle is very small. Thus it is concluded that the later part of the tunnel shows a relatively good separation capability at high flow rates, but the separation effect is reduced at lower flow rates, which can be explained by the small size of the particles in the water.

Municipal separate storm sewer system (MS4) permittees face costly obligations to reduce pollutant loadings needed to achieve waste load allocations (WLAs) and meet total maximum daily loads (TMDLs). Street sweeping is potentially an effective BMP since streets exist throughout urban watersheds, often are directly connected to the storm sewer, and are found to contain an abundance of contaminants. Although pollutant removal from street sweeping has been evaluated for decades, an understanding of the impact on water quality in receiving streams is elusive. Due to numerous variables, the large number of samples necessary to measure impact in receiving streams may never be obtained. In response, modeled pollutant removal efficiencies based on frequency of sweeping have been recommended to the Chesapeake Bay Program, but these results are suspect. Alternatively, the amount of swept material has emerged as a method to quantify reductions. A sampling study was conducted to measure pollutants in swept material. The study identified the fraction of material susceptible to transport in runoff based on timing of sweeping in relation to runoff events. Based on observed pollutant concentration associations with particle size, the study results in estimates of pollutant concentrations for the fraction of material susceptible to downstream transport, dependent on duration since the last rainfall and type of surface swept, whether the area is a streets or a parking lot. Pollutant loadings and required reductions to achieve the Chesapeake Bay WLAs for various land use sample areas are computed for an average year. Modeled removal efficiencies and results from the sampling study were employed to assess impacts from street sweeping. Modeled efficiencies predict significantly lower impact than measurements of pollutants susceptible to runoff in swept material. Modeled loadings are inconsistent with measurements of swept materials and the rigorous sweeping frequency required for modeled removal efficiency credit appears to be unnecessary.
Doctor of Philosophy

Regnvatten, smältvatten och spolvatten som rinner av från hårdgjorda ytor kallas dagvatten. Dagvatten är ofta förorenat av tungmetaller eller svårnedbrytbara organiska ämnen, som kan göra stor skada om vattnet inte renas innan det når recipienten. I dagsläget finns det inga nationellt fastslagna riktvärden för föroreningshalter i dagvatten. Dagvattengruppen på Vattenfall AB Värme Uppsala har tillsammans med miljökontoret i Uppsala tagit fram riktvärden för föroreningshalter från kvarteret Brännugnen, som området som studerats i detta examensarbete kallas. Vattenfall har idag problem med att klara dessa riktvärden för bland annat metaller i en del av kvarterets dagvattenbrunnar. För att reducera utsläppet av föroreningar till dagvattennätet från kvarteret Brännugnen har därför denna dagvattenutredning genomförts. Genom platsundersökningar och provtagning på dagvattnet i sex punkter har källor till föroreningar identifierats. Förslag på åtgärder har tagits fram genom litteraturstudier, platsundersökningar och samtal och diskussioner med erfaren personal. Studien har också resulterat i förslag på en förbättrad provtagningsstrategi som ger en mer korrekt bild av utsläppta mängder föroreningar per år. Målsättningen var att den nya provtagningsstrategin skulle vara mer kostnadseffektiv vilket uppnåddes. I dagvattenstudien undersöktes också om rening sker i det underjordiska magasin som dagvattnet från halva kvarteret Brännugnen leds till. Resultatet visade att ingen rening sker i magasinet, då uppehållstiden är för kort för att partiklar ska hinna sedimentera. Förutom vatten från regn- och snösmältning kommer även kondensat och processvatten till dagvattennätet från kvarteret Brännugnen. Ett av målen i utredningen var att undersöka hur mycket kondensatet bidrar till den utsläppta mängden metaller. Provtagning av kondensat och dagvatten visade tillsammans med flödesberäkningar att kondensatet har en stor påverkan på hur stor mängd förorening som släpps ut per år. Riktvärden studerades också i denna dagvattenutredning, slutsatsen är att de riktvärden som Vattenfall förhåller sig till i dag är låga. Både schablonhalterna för värmeverk och vägdagvatten samt analysresultat av dagvatten från vägen utanför området överskrider Vattenfalls riktvärden för dagvatten. Slutligen skulle dagvattenstudien resultera i förslag på framtida åtgärder för rening av dagvattnet från kvarteret Brännugnen i form av tekniska lösningar. Avsättningsmagasin under mark och filteranläggning är två lösningar som är lämpliga för rening av dagvattnet med hänsyn till föroreningar och flöden. Kostnaden beror mycket på vilket flöde som blir dimensionerande.
Stormwater is rain and snow melt that runs off from hard surfaces. Stormwater is often polluted with heavy metals and organic pollutants, which can cause great damage if the water is not treated before it reaches the recipient. There are no national guidelines for threshold values of pollutants in stormwater. The stormwater group at Vattenfall AB Heat Uppsala and the environmental department at Uppsala municipality have together established threshold values for pollutants in the stormwater from the area Brännugnen, which is the name of the investigated area. Vattenfall has difficulties to keep the concentration of pollutants in the stormwater below the threshold values. To reduce the content of contaminants in the stormwater from the area Brännugnen this study was therefore carried out. Through site investigations and sampling of stormwater in six measuring points, sources of the contaminants were identified. Through literature studies, site investigations and discussions with experienced personnel, propositions of actions to avoid contamination of the stormwater have been developed. The stormwater study has also led to suggestion of an improved sampling strategy which better represents the amount of contaminants in the stormwater and is more cost-effective. The study included an investigation with the purpose to find out if the magazine that the stormwater from half of the area runs to have the capacity to reduce the contaminants. The results showed no reduction of contaminants. The reason is that the residence time is too short for the particles to have time to settle. In the study the contribution from condensate to the total amount of emitted metals in the stormwater was investigated. The condensate passes a treatment plant for purification before being discharged to the stormwater pipes. The result shows that the condensate has a large impact on the amount of emitted metals per year. Threshold values and standard values for stormwater was also studied, the conclusion is that the threshold values for the stormwater from the area Brännugnen are low. Both standard values for stormwater from thermal power stations and roads are higher than the threshold values. The results from the analyses of stormwater from the road outside the area Brännugnen also show higher concentrations of metals than the threshold values. Finally the stormwater study resulted in suggestions of technical solutions for future treatment of the stormwater from the area Brännugnen. An underground sedimentation magazine and a filter system are two treatment processes that can be used for removal of pollutants in the stormwater from the area Brännugnen.

Stormwater run-off from surfaces such as roads or rooftops is often polluted with heavy metals and nutrients. Many of these substances can cause great damage in biota if they end up in the recipient. In Sweden constructed wetlands and ponds for treatment of stormwater are frequently used, since research has shown that these treatment ponds are reducing stormwater pollution considerably to a low cost. The knowledge of these pollutant removal mechanisms and how follow-up and assessment of the ponds should be performed is still limited.

To determine the pollutant removal efficiency of the stormwater ponds it is recommended that flow-weighted water samples are collected from both the inflow and the outflow of the pond. This method demands considerable resources of time and money for installations and analysis. Alternative methods for assessing pollutant removal are requested, methods with lower costs but relevant results. This thesis is investigating whether sediment sampling could be such an alternative.

Sediment core samples were taken in four stormwater ponds where flow-weighted water sampling has been performed as well. This makes it possible to compare the two methods. A method of sampling recently sedimented material was also tried out by constructing and placing sediment traps on the pond floor. Analysis of concentration of six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and phosphorus were carried out.

The results show i.e. that the concentrations of heavy metals and phosphorus in the pond sediments decrease as the distance from the pond inlet increase. Comparing the two methods shows that the results from the sediment sampling are in the same order of magnitude as the results from the water sampling. Consequently, the conclusion states that a well executed sediment sampling may be an alternative to flow-weighted water sampling.

NOS dagvatten

The river Göta Älv reaches between Vänern and Gothenburg and is the main raw water source for Gothenburg that supplies about 700 000 people with water. To protect and maintain a high water quality, continuously samples and water analyses are made throughout the river. In 1998 a protection area was founded between surte and Lärjeholm where the raw water intake is. This was made to increase the awareness of the importance to protect the water. However, there is a lot of contribution of untreated stormwater to Göta Älv within the protection area.

Göteborg Water and Sewage Works commissioned this thesis where two areas, Tagene industrial area and Kärra residential area, with untreated stormwater outlets within the protection area are studied. The areas have been divided according to surface composition with different rates of pollutant contribution. Then the stormwater flow and the contribution of pollutants was simulated with the model SEWSYS. The future aim is that the model will be able to simulate the contribution of pollutants for a variety of rains, for the whole protection area.

SEWSYS (Sewer System) is built in MATLAB/Simulink and consists of three modules, a stormwater module, a sanitary wastewater module and a treatment plant module. This project only includes the stormwater module. The model simulates the stormwater flow and the pollutants total phosphorous, total nitrogen, copper, zinc, lead, cadmium and polycyclic aromatic hydrocarbons (PAH). Samples and analysis for the two areas has been carried out for another thesis work during the same period. The results from those analyses have been used for the model settings for the areas.

Simulations have been performed to adjust the model and evaluate its ability to describe the stormwater flow and the pollutant contribution within the areas. The amount of stormwater and the runoff are well simulated by the model. However, the measured and analysed data has not been enough to get reliable simulations over the pollutant contribution. Further development of the model is necessary. Generally the model simulates lower values compared to measured values, especially in the industrial area. For a more general understanding over how SEWSYS works for the two areas, simulations were carried out on a yearly basis. Those simulations have been compared with general data for stormwater pollutants. Even though the results from the simulations have shown lower values than the measured values, the model shows clearly that the contribution of pollutants from the industrial site is greater than the contribution from the residential site.

Göta Älv sträcker sig från Vänern ner till Göteborg och är Göteborgs huvudsakliga råvattentäkt som försörjer ca 700 000 personer med vatten dagligen. För att säkra råvattenkvaliteten görs kontinuerliga provtagningar utmed älven. Dessutom beslutade Länsstyrelsen 1998 om ett skyddsområde med skyddsföreskrifter för avrinningsområdet mellan Surte i norr till vattenintaget vid Lärjeholm i söder. Ett mål med skyddsområdet är att det ska öka medvetenheten hos boende och de som är verksamma inom området om behovet att värna om vårt vatten. Dock leds det på flera ställen ut orenat dagvatten till älven inom skyddsområdet.

Examensarbetet är ett uppdrag av Göteborgs Va-verk där två områden med orenade dagvattenutsläpp till Göta Älv studeras, Tagene industriområde samt Kärra bostadsområde. Dessa områden har karterats och dagvattenflödet samt föroreningsbelastningen från dagvattnet har simulerats med modellen SEWSYS. Målet på lång sikt är att modellen ska kunna användas för att simulera föroreningsbelastningen vid olika regn för hela skyddsområdet.

Modellen SEWSYS (Sewer System) är uppbyggd i MATLAB/Simulink och bygger på tre moduler, en dagvattenmodul, en spillvattenmodul och en reningsverksmodul. För detta projekt har endast delen för dagvatten använts. Modellen simulerar dagvattenflödet och behandlar föroreningarna totalfosfor, totalkväve, koppar, zink, bly, kadmium samt polycykliska aromatiska kolväten (PAH). I ett examensarbete parallellt med detta har provtagning och analyser av föroreningar för de båda områdena ägt rum och dessa värden ligger till grund för inställningen av modellen.

Simuleringar har utförts för att anpassa modellen samt utvärdera dess förmåga att beskriva dagvattenflödet och föroreningsbelastningen inom de aktuella områdena. Simuleringarna visar att avrinningen och dagvattenflödet simuleras bra av modellen. Det har dock visat sig att de gjorda mätningarna inte har varit tillräckliga som underlag för att få en tillförlitlig beskrivning av föroreningsbelastningen och vidare utveckling är nödvändig. Detta gäller särskilt i industriområdet där modellen generellt simulerar för låga föroreningsmängder. För en mer allmän uppfattning av SEWSYS modellen för de två områdena, har även simuleringar på årsbasis utförts och jämförts med schablonhalter för dagvattenföroreningar. Trots att simuleringsvärdena har legat lägre än de uppmätta värdena på föroreningsmängderna har det gått att visa att industriområdet bidrar till högre föroreningsbelastning än bostadsområdet på recipienten Göta Älv.

Urban and agricultural runoff is the principal contributor to non-point source (NPS) pollution and subsequent impairments of streams, rivers, lakes, and estuaries. Urban and agricultural runoff is a major source of sediment, nitrogen (N) and phosphorus (P) loading to receiving waters. Coastal waters in the southeastern U.S. are vulnerable to human impacts due to the proximity to urban an agricultural land uses, and hydrologic connection of the Coastal Plain to receiving waters. To mitigate the impacts of urban and agricultural runoff, a variety of stormwater control measures (SCMs) are implemented. Despite the importance of the Coastal Plain on water quality and quantity, few studies are available that focus on prediction of nutrient and sediment runoff loads from Coastal Plain watersheds. The overall goals of my dissertation are to assess the effect of urban and agricultural watershed on coastal waters through monitoring and modeling, and to characterize treatment performance of SCMs. These goals are addressed in four independent studies. First, we developed the Storm Water Management Model (SWMM) and the Hydrologic Simulation Program-Fortran (HSPF) models for an urbanized watershed to compared the ability of these two models at simulating streamflow, peak flow, and baseflow. Three separate monitoring and modeling programs were conducted on: 1) six urban land uses (i.e. commercial, industrial, low density residential, high density residential, transportation, and open space); 2) container nursey; and 3) a Coastal Plain retention pond. This study provides methods for estimating watershed pollutant loads. This is a key missing link in implementing watershed improvement strategies and selecting the most appropriate urban BMPs at the local scale. Results of these projects will help urban planners, urban decision makers and ecological experts for long-term sustainable management of urbanized and agricultural watersheds.
Doctor of Philosophy
Urban and agricultural runoff is a major source of sediment, nitrogen (N) and phosphorus (P) loading to receiving waters. When in excess, these pollutants degrade water quality and threaten aquatic ecosystems. Coastal waters in the southeastern U.S. are vulnerable to human impacts due to the proximity to urban an agricultural landuse. To mitigate the impacts of urban and agricultural runoff, a variety of stormwater control measures (SCMs) are implemented. The overall goals of my dissertation are to assess the effect of urban and agricultural watershed on coastal waters through monitoring and modeling, and to characterize treatment performance of SCMs. These goals are addressed in four independent studies. First, we developed two watershed models the Storm Water Management Model (SWMM) and the Hydrologic Simulation Program-Fortran (HSPF) to simulate streamflow, peak flow, and baseflow within an urbanized watershed. Three separate monitoring programs were conducted on: (1) urban land uses (i.e. commercial, industrial, low density residential, high density residential, transportation, and open space); (2) container nursey; and (3) a Coastal Plain retention pond. These studies provided methods for estimating watershed pollutant loads. Results of these projects will help urban planners and ecological experts for long-term sustainable management of urbanized and agricultural watersheds.

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

Dagvatten kallas det regn- och smältvatten som rinner av från hårdgjorda ytor i stadsmiljön. Detta vatten för ofta med sig stora mängder av föroreningar som tungmetaller, näringsämnen och oljerelaterade ämnen, vilka kan göra stor skada om de når recipienter. För att rena dagvattnet och därmed minska föroreningsbelastningen byggs det allt fler öppna dagvattensystem som t.ex. våtmarker och dammar. Studier har visat att dessa system har hög reningseffekt och dessutom är de kostnadseffektiva. Kunskapen om hur avskiljningen i dessa system fungerar och om hur de bäst utvärderas är dock begränsad. Kungsängsdammen utanför Uppsala är en nybyggd dagvattenanläggning som är avsedd att rena och fördröja dagvattnet från industri- och handelsområdet Boländerna. Detta examensarbete syftar till att utreda reningsfunktionen av anläggningen. Framför allt genomfördes flödesproportionell provtagning vid inlopp och utlopp under 8 veckor. Ämnen som analyserades var näringsämnena P och N, suspenderat material, tungmetallerna As, Cd, Co, Cr, Cu, Mo, Ni, Pb, V, Zn och oljekolväten. Vid några tillfällen analyserades också de oljerelaterade organiska föreningarna PAH:er, oktyl- och nonylfenoler samt tributyltenn. Flödesproportionell provtagning rekommenderas för att säkert avgöra avskiljningseffektiviteten av en damm, men nackdelen är att den tar mycket tid och stora resurser i anspråk. Utöver denna metod genomfördes kompletterande mätningar med sedimentfällor samt en beräkning av föroreningsbelastning vid inloppet med programmet StormTac. Den flödesproportionella provtagningen visade att Kungsängsdammen fungerar väl som avskiljningsanläggning för föroreningar. Suspenderat material, näringsämnen och tungmetaller avskiljs effektivt och utloppshalterna understiger föreslagna riktvärden för dagvatten. Detta trots att både zink, koppar, kväve och suspenderat material hade inloppshalter som låg över riktvärdena. Flödesberäkningar visade att andelen av flödet som bräddas i bypass-diket förbi dammen är viktig vid bedömning av avskiljningseffektiviteten. För organiska föreningar uppmättes tributyltenn i halter över miljökvalitetsnormen för ytvatten både vid inlopp och vid utlopp. Inloppskoncentrationer framräknade i StormTac gav överensstämmande resultat med den flödesproportionella provtagningen för tungmetaller och näringsämnen. Vidare visade undersökningen av sediment att sedimentationen sker främst i fördiket och i inloppet till dammen. Fördiket är i stort behov av rensning, då sediment riskerar att spolas bort vid höga flöden.
Stormwater is the name for rainwater and snowmelt runoff from impervious surfaces in the urban environment. This water often carries large amounts of pollutants such as heavy metals, nutrients, and oil-related substances, which can cause great damage if they reach the receiving waters. To clean the storm water and thus reduce the pollution load, more and more open storm water systems are being built, such as wetlands and ponds. Studies have shown that these systems have high pollutant removal efficiency and are cost effective. Knowledge of how these systems work and how they best are evaluated is limited. “Kungsängsdammen” near Uppsala is a newly constructed stormwater facility that is designed to clean and retard stormwater from the industrial and commercial area Boländerna. This thesis aims to investigate the purification function of the facility. Flow proportional sampling was carried out at the inlet and outlet for 8 weeks. Substances that were analyzed were nutrients P and N, suspended solids, heavy metals As, Cd, Co, Cr, Cu, Mo, Ni, Pb, V, Zn and petroleum hydrocarbons. On some occasions, the petroleum-related organic parameters PAHs, octyl and nonylphenols and tributyltin were analyzed. Flow proportional sampling is recommended to determine the efficiency of a stormwater pond, but the problem is that it takes much time and considerable resources. In addition to this method, additional measurements were carried out with sediment traps, and a calculation of pollution load at the inlet with the program StormTac. The flow proportional sampling showed that the “Kungsängsdammen” pond-, functions well as a treatment facility for pollutions. Suspended solids, nutrients and heavy metals are separated effectively and the outlet concentrations for these substances were below proposed guideline values. This is observed, despite the fact that zinc, copper, nitrogen and suspended solids had intake concentrations above the guideline values. Flow calculations showed that the bypass flow is important when estimating the pollutant removal efficiency. For organic compounds, tributyltin was measured at concentrations above the Environmental Quality Standards (EQS) for surface water both at the inlet and outlet. The inlet concentrations that were calculated in StormTac were consistent with the results of the flow proportional sampling for heavy metals and nutrients. Moreover, the investigation of sediments showed that sedimentation occurs mainly in the ditch before the pond and at the inlet to the pond. The ditch is in need of cleansing, because of the risk of sediment being washed away during high flows. The flow proportional sampling showed that the “Kungsängsdammen” pond-, functions wellas a treatment facility for pollutions. Suspended solids, nutrients and heavy metals are separated effectively and the outlet concentrations for these substances were below proposedguideline values. This is observed, despite the fact that zinc, copper, nitrogen and suspended solids had intake concentrations above the guideline values. Flow calculations showed that the bypass flow is important when estimating the pollutant removal efficiency. For organiccompounds, tributyltin was measured at concentrations above the Environmental Quality Standards (EQS) for surface water both at the inlet and outlet. The inlet concentrations that were calculated in StormTac were consistent with the results of the flow proportional sampling for heavy metals and nutrients. Moreover, the investigation of sediments showedthat sedimentation occurs mainly in the ditch before the pond and at the inlet to the pond. The ditch is in need of cleansing, because of the risk of sediment being washed away during high flows.

Hamrebäcken rinner genom östra delen av Västerås och har Mälaren som recipient. Under bäckens flödesväg tillkommer dagvatten och föroreningar i form av näringsämnen och tungmetaller från dess avrinningsområde. Bäcken utgör ett av de mest prioriterade vattendragen i Västerås gällande utsläpp av dagvatten. Detta examensarbete har utförts med syftet att utreda föroreningssituationen för Hamrebäcken och hur dess recipient Mälaren påverkas. Examensarbetet syftade även till att undersöka reningseffekten för en befintlig dagvattendamm samt att utifrån ett kostnads- och reningsperspektiv beskriva ett antal åtgärdsförslag för att uppnå en förbättring av bäckens ekologiska och kemiska status. Utvärdering av Hamrebäckens föroreningsbelastning samt reningseffekt för befintlig dagvattendamm och åtgärdsförslag utfördes med hjälp av den Excelbaserade dagvatten- och recipientmodellen StormTac.   Resultatet från studien visade att den modellerade belastningen från flera av bäckens delavrinningsområden överskrider föreslagna riktvärden för mindre vattendrag. Den totala belastningen från Hamrebäckens avrinningsområde överskrider i fallet för föroreningarna bly och suspenderat material även föreslagna riktvärden för Mälaren. Modellering av den befintliga dammen indikerar att anläggningen är underdimensionerad i förhållande till dess belastningsyta. Dammens reningseffekt uppnår inte heller effektmålen i Västerås stads handlingsplan för dagvatten. Ett förslag om utbyggnation av dammen har tagits fram utifrån litteraturstudie och tillgänglig yta för åtgärden. Den simulerade ombyggnationen uppnådde inte uppsatta effektmål men gav en betydande ökning i reningseffekt. Åtgärder som syftar till att öka dammens avskiljningsförmåga bör därför utredas ytterligare.   Fyra ytterligare åtgärdsförslag togs fram och reningseffekten av dessa modellerades i StormTac. Detta inkluderade två olika placeringar av dagvattendammar, en skärmbassäng med flytande våtmark, samt en konstruerad våtmark. Från genomförd modellering rekommenderas vidare utredning av åtgärdsförslagen inkluderande ett anläggande av en skärmbassäng med flytande våtmark, alternativt en konstruerad våtmark. Detta då dessa åtgärdsförslag uppnådde effektmålen för rening enligt Västerås stads handlingsplan för dagvatten. Åtgärdsförslagen skilde sig något åt gällande kostnadseffektivitet. Detta ansågs dock inte ensamt vara argument nog för att motivera anläggning av något åtgärdsförslag till följd av osäkerheter i det beräknade resultatet. Att en skärmbassäng kan utföras i närtid och inte kräver några ingrepp i avrinningsområdet kan anses som ytterligare argument för installation av anläggningen. En konstruerad våtmark kan i sin tur motiveras med att anläggningen bidrar till att höja det estetiska och ekologiska värdet av området. Dessa argument bör beaktas i valet av metod och det fortsatta arbetet med att minska områdets föroreningsbelastning och förbättra bäckens ekologiska och kemiska status.
Hamrebäcken is a small stream in Västerås, which flows through the eastern part of the city. Along it’s course to Lake Mälaren, the stream receives polluted stormwater containing such as heavy metals and nutrients. The primary objective of this master thesis was to investigate the level of pollutants in Hamrebäcken. A secondary objective was to study the reduction efficiency of an existing wet stormwater treatment pond in the area, and propose ways in which to achieve a higher ecological and chemical status for the stream. The stormwater and recipient software model StormTac was used to estimate the level of pollutants and to investigate the reduction efficiencies of different stormwater treatment facilities.   The study revealed that pollutant levels were too high for several of the subwatersheds, based on the recommended guidance for small streams. The pollutant load for the total watershed exceeded the guidance levels for Lake Mälaren for lead and suspended solids. Modelling the reduction efficiency of the existing wet pond indicated that the pond’s size was inadequate to cater for the quantity of incoming stormwater in need of treatment. Subsequently, the pollution reduction efficiency of the pond was not meeting those objectives set out in the Stormwater Action Plan developed by Västerås municipality. A proposal for rebuilding the pond was therefore developed, taking into account the existing conditions of the area and using recommendations from literature. When modeled in StormTac, the modified pond showed a substantial increase in reduction efficiency compared to that of the existing pond. Despite not reaching the objectives of the Action Plan, this suggested that it would be beneficial to investigate measures that increase the reduction efficiency of the existing wet pond further. As a result, an additional four alternatives for reducing the pollutant load of Hamrebäcken were developed using StormTac. These consisted of two wet stormwater treatment ponds at different locations within the watershed, a screen basin with floating treatment wetlands, and a constructed wetland.   The modeling revealed that the most feasible of the investigated measures was an installation of either a screen basin with floating treatment wetlands or a constructed wetland, both measures adjacent to the outlet of Hamrebäcken. This was mainly due to the modeled reduction capacity of these measures where the reduction objectives of the Action Plan were reached. A difference in cost effectiveness was found between the different measures. This was however not considered to solely be argument to justify the implementation of a certain measure due to uncertainties in the modelled result. The fact that a screen basin can be installed in the near future and without occupying space in the watershed are additional arguments for the use of this measure. A constructed wetland can in return be motivated by a potential increase in esthetic and ecological value of the area. These arguments should be considered in the continued investigation of choosing a measure for reducing the pollutant load of Hamrebäcken and to achieve a higher ecological and chemical status for the stream.

Thesis (M.S.)--University of Wisconsin--Madison, 1995.
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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.
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Nonpoint source (NPS) pollution is one of the leading causes of water quality problems in the United States. Bioretention has become one of the more frequently used stormwater management practices for addressing NPS pollution in urbanized watersheds in New England. Yet despite increased acceptance, bioretention is not widely practiced. This study explores and evaluates the efficacy of bioretention for protecting urban water quality. This research found that numerous monitoring methods are used by researchers and industry experts to assess the effectiveness of stormwater best management practices (BMPs) and low impact development (LID) practices that include bioretention. The two most common methods for analyzing and evaluating water quality data are pollutant removal efficiency and effluent quality. While effluent quality data is useful for characterizing classes of BMP treatment performance on a statistical basis, pollutant removal efficiency is more representative of the actual pollutant load being reduced by the stormwater treatment practice over time, and is used in Total Maximum Daily Load (TMDL) assessments. However, despite this difference, monitoring is still arguably the best method for determining the effectiveness of stormwater treatment practices. Monitoring of bioretention performance results is needed to inform improvements to design standards and guidance to aid state and local municipalities in the proper selection of bioretention/stormwater controls. This study advocates for instituting fine-scale, “safe-to-fail” design experiments as part of an adaptive management process that is used to advance bioretention design guidance and future applications of monitoring practice(s) that target reduction of pollutants in downstream receiving waterbodies. This innovative approach could result in increased use of bioretention in New England urban environments.