Stormwater Quantity Research Articles

Removal of Heavy Metals from Urban Stormwater using Pervious Concrete

Removal of Heavy Metals from Urban Stormwater using Pervious ConcretePervious concrete is a sustainable alternative to conventional impervious pavement materials because it allows water to infiltrate into the subsurface, thus solving problems associated with stormwater quantity and quality. This study aims to deepen the understanding of the chemical processes involved in removing heavy metals using pervious concrete. A percolation testing system was developed to...Author(s)Austin WeidnerArthur KneyMuhannad T. SuleimanDerek RidingerSourceProceedings of the Water Environment FederationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2012ISSN1938-6478DOI10.2175/193864712811699401Volume / Issue2012 / 5Content sourceStormwater SymposiumCopyright2012Word count168

Development of a Bioretention Cell Model and Evaluation of Input Specificity on Model Accuracy

With the implementation of Phase II of the National Pollutant Discharge Elimination System (NPDES), municipalities have new requirements to reduce stormwater quantity and enhance water quality. Bioretention cells (BRCs) are a pollution mitigation option that can address the new regulations. In order to implement BRCs in the landscape, models are needed so stormwater engineers and managers can estimate the impact of the mitigation technique. While several BRC models are available, users must supply input parameters, which are many times poorly understood. The objective of this work was to determine the level of input specificity in hydraulic parameters needed to accurately estimate water movement through a BRC. A water movement model was developed that incorporates infiltration, drainage, and overflow for a single storm event. Then pilot-scale BRCs were constructed and operated to obtain data for model testing. The model was run with four sets of input parameters with increasing specificity: soil type, fraction sand/silt/clay, an adjustment for bulk density, and a macropore routine to serve as a fitting parameter. While the model with the highest input specificity proved to match experimental values closest (drainage volume between 0.7% and 8.8% from observed, and maximum drainage flow rate between 1.4% and 18% from observed), it is unlikely that stormwater managers would have access or time to obtain this information. However, a simulation with the fraction sand/silt/clay and an adjustment for bulk density provided acceptable results (drainage volume between 0.7% and 18% from observed, and maximum drainage flow rate between 30% and 39% from observed).

Cost Comparison of Conventional Gray Combined Sewer Overflow Control Infrastructure versus a Green/Gray Combination

AbstractThis paper outlines a life-cycle cost analysis comparing a green (rain gardens) and gray (tunnels) infrastructure combination to a gray-only option to control combined sewer overflow in the Turkey Creek Combined Sewer Overflow Basin in Kansas City, MO. The area of this basin is 2,248 ha (5,554 acres). A set of spreadsheets was developed upon which this life-cycle cost analysis is based. The spreadsheets allow the user to vary the length and/or the diameter of the tunnels. The spreadsheets calculate the additional number of rain gardens needed to handle a given amount of stormwater when the tunnel sizes are reduced. The difference in life-cycle costs between the green/gray and gray-only alternatives is calculated. For a range of options for the number of rain gardens, the green/gray combined alternative is more cost-effective than the gray-only option. The potential present worth of the cost savings for the 50-year expected lifespan of both the gray and green infrastructure could reach as much as $...

Off-Stream Detention Design for Storm-Water Management

AbstractA detention basin is designed for storm-water quantity and quality controls. An in-stream basin is often located on a widened floodplain, whereas an off-stream basin can be part of open space in a parking lot, park, or sport field. The inflow channel associated with an off-stream basin is allowed to carry its base flow not to exceed the downstream capacity. When the inflow channel is full, the excess flood water is diverted into the off-stream basin through the side weir. During the flood recession, the equalizer conduit drains the basin flow back to the channel. In this study, the rational volumetric method was expanded from in-stream to off-stream detention design. The required off-stream detention volume is maximized by the rainfall event longer than the time of concentration of the tributary area. In comparison, the off-stream detention volume can be significantly less than an in-stream, depending on the flow-through capacity in the downstream channel. This paper presents a design procedure to...

Characterization of Green Roof Stormwater Runoff Quality

Green roofs are recognized as effective means of stormwater quantity control through runoff volume reduction and peak discharge attenuation. A properly designe…

Biophysical properties and thermal performance of an intensive green roof

Green roofs have been increasingly enlisted to alleviate urban environmental problems associated with urban heat island effect and stormwater quantity and quality. Most studies focus on extensive green roofs, with inadequate assessment of the complex intensive type, subtropical region, and thermal insulation effect. This study examines the physical properties, biological processes, and thermal insulation performance of an intensive green roof through four seasons. An experimental woodland installed on a Hong Kong building rooftop was equipped with environmental sensors to monitor microclimatic and soil parameters. The excellent thermal performance of the intensive green roof is verified. Even though our site has a 100 cm thick soil to support tree growth, we found that a thin soil layer of 10 cm is sufficient to reduce heat penetration into building. Seasonal weather variations notably control transpiration and associated cooling effect. The tree canopy reduces solar radiation reaching the soil surface, but the trapped air increases air temperature near the soil surface. The substrate operates an effective heat sink to dampen temperature fluctuations. In winter, the subtropical green roof triggers notable heat loss from the substrate into the ambient air, and draws heat upwards from warmer indoor air to increase energy consumption to warm indoor air. This finding deviates from temperate latitude studies. The results offer hints to optimize the design and thermal performance of intensive green roofs.

The Runoff Reduction Method

Abstract:The Runoff Reduction Method (RRM) provides an innovative approach to crediting the total performance of stormwater best management practices (BMPs). Total BMP performance refers to the pollutant removal and runoff volume reduction capabilities. The RRM tracks the implementation of stormwater BMPs, including Low Impact Development (LID) strategies such as permeable pavement, rainwater harvesting, downspout disconnection, soil amendments, etc., and credits the appropriate runoff volume reduction, pollutant concentration reduction, or both towards compliance with stormwater quality and quantity requirements. By providing a mechanism to credit the volume reduction associated with these LID strategies the RRM also documents an allowable reduction of the overall size and footprint of structural detention practices, thereby providing an economic incentive for the development community to implement LID providing a better overall solution for minimizing the impact of development on the hydrologic cycle.

Bioretention processes for phosphorus pollution control

Phosphorus is a water pollutant of concern around the world as it limits the productivity of most freshwater systems which can undergo eutrophication under high phosphorus inputs. The importance of treating stormwater as part of an integrated phosphorus pollution management plan is now recognized. Bioretention systems are urban stormwater best management practices (BMPs) that rely on terrestrial ecosystem functions to retain storm flows and reduce pollutant loads. Bioretention has shown great potential for stormwater quantity and quality control. However, phosphorus removal has been inconsistent in bioretention systems, with phosphorus leaching observed in some systems. Numerical models can be used to predict the performance of bioretention systems under various conditions and loadings. The aim of this paper is to identify and characterize bioretention phosphorus cycling processes, with a particular focus on process modelling. Both soluble and particulate phosphorus forms are expected in significant proportions in bioretention system inflows. Sorption mechanisms are expected to dominate soluble phosphorus cycling, while particulate phosphorus transport occurs mainly through sedimentation. Vegetative uptake, mineralization, and immobilization are also known to play a role in the cycling of phosphorus; however, data is lacking to assess their importance. There is a need for simple mathematical equations to represent dissolution and precipitation reactions in bioretention systems. More research is also needed to characterize the rates of colloidal capture and mobilization within soils. Finally, approaches used to model phosphorus transport in systems similar to bioretention are not applicable to bioretention system modelling. This reinforces the need for the development of a bioretention phosphorus transport model.

Stormwater quantity and quality response to climate change using artificial neural networks

AbstractThis research investigates the potential impacts of climate change on stormwater quantity and quality generated by urban residential areas on an event basis in the rainy season. An urban residential stormwater drainage area in southeast Calgary, Alberta, Canada is the focus of future climate projections from general circulation models (GCMs). A regression‐based statistical downscaling tool was employed to conduct spatial downscaling of daily precipitation and daily mean temperature using projection outputs from the coupled GCM. Projected changes in precipitation and temperature were applied to current climate scenarios to generate future climate scenarios. Artificial neural networks (ANNs) developed for modelling stormwater runoff quantity and quality used projected climate scenarios as network inputs. The hydrological response to climate change was investigated through stormwater runoff volume and peak flow, while the water quality responses were investigated through the event mean value (EMV) of five parameters: turbidity, conductivity, water temperature, dissolved oxygen (DO) and pH. First flush (FF) effects were also noted. Under future climate scenarios, the EMVs of turbidity increased in all storms except for three events of short duration. The EMVs of conductivity were found to decline in small and frequent storms (return period < 5 years); but conductivity EMVs were observed to increase in intensive events (return period ≥ 5 years). In general, an increasing EMV was observed for water temperature, whereas a decreasing trend was found for DO EMV. No clear trend was found in the EMV of pH. In addition, projected future climate scenarios do not produce a stronger FF effect on dissolved solids and suspended solids compared to that produced by the current climate scenario. Copyright © 2010 John Wiley & Sons, Ltd.

Low Impact Development Design—Integrating Suitability Analysis and Site Planning for Reduction of Post-Development Stormwater Quantity

A land-suitability analysis (LSA) was integrated with open-space conservation principles, based on watershed physiographic and soil characteristics, to derive a low-impact development (LID) residential plan for a three hectare site in Coshocton OH, USA. The curve number method was used to estimate total runoff depths expected from different frequency storms for: (i) the pre-development condition, (ii) a conventional design, (iii) LID design based on the LSA of same building size; and (iv) LID design based on the LSA with reduced building footprints. Post-development runoff depths for the conventional design increased by 55 percent over those for the pre-development condition. Runoff depth for the same building size LSA-LID design was only 26 percent greater than that for the pre-development condition, and 17% for the design with reduced building sizes. Results suggest that prudent use of LSA may improve prospects and functionality of low-impact development, reduce stormwater flooding volumes and, hence, lower site-development costs.

Low Impact Development for Stormwater Quantity and Quality

Low impact development, also known as LID, is an innovative stormwater management approach modeled after nature. This chap-ter provides information and case st…

An urban drainage stormwater quality model: Model development and uncertainty quantification

Summary The evaluation of urban stormwater quality is of relevant importance for urban drainage, and mathematical models may be of great interest in this respect. To date, several detailed mathematical models are available to predict stormwater quantity–quality characteristics in urban drainage systems. However, only a few models take sewer sediments into account, considering their cohesive-like properties that influence the build-up process of the pollutant load. Furthermore, the model data requirements, especially for the quality aspects, are extensive, which limit their applicability and affect model results with large uncertainty. Uncertainty analysis provides a measure or index regarding the significance and the accuracy of the results obtained by mathematical modelling and is therefore of high interest. Nevertheless, only few studies have been carried out in the urban drainage field, and very few deal with water quality issues. One of the main reasons for this lack of research is the computational burden required by detailed models that preserve this analysis and generally require several Monte Carlo simulation runs. A possible to this problem may be the adoption of simplified parsimonious models that generally require shorter computational times. In this context, this paper presents a parsimonious conceptual model for the evaluation of the pollutant load in-sewers. The model contains two modules: a hydrological and hydraulic module that calculates the hydrographs at the inlet and at the outlet of the sewer system, and a solid transfer module that calculates the pollutographs. The cohesive properties of sewer sediments were carefully considered. Further, the effectiveness of the innovative sewer sediment modelling approach has been verified by taking into account the uncertainty assessed according to the GLUE methodology. The model has been tested using experimental quantity–quality data gathered in two Italian catchments, Fossolo (Bologna) and Parco d’Orleans (Palermo).

A technical decision-making framework: stormwater as an alternative supply source

Stormwater harvesting is a relatively new concept which has developed using traditional stormwater management practices as well as water resourcing and holistic water management concepts. While stormwater harvesting systems have been designed and constructed in the past, the planning and design processes have not followed an integrated approach. This paper addresses this issue and describes a decision-making framework (DMF) that determines the most appropriate stormwater harvesting scheme option based primarily on technical feasibility and financial costs with a focus on neighbourhood-scale development. A case study of an existing urban area in the suburb of Sunshine in Melbourne, Australia, was conducted to demonstrate the DMF. Comparison of all stormwater harvesting scheme options determined that while one scheme option was the most effective option in terms of cost, reliability, quantity of stormwater used and end uses met, several other options could also be examined further for detailed analysis.

Review of Stormwater Quality, Quantity and Treatment Methods Part 2: Stormwater: Quality Modelling

Review of Stormwater Quality, Quantity and Treatment Methods Part 2: Stormwater: Quality Modelling

Stormwater Runoff Quality and Quantity From Traditional and Low Impact Development Watersheds1

Abstract: The quality and quantity of residential stormwater runoff from a control, traditional, and low impact development (LID) watershed were compared in a paired watershed study. A traditional neighborhood was built using typical subdivision standards while a LID design was constructed with best management practices including grass swales, cluster housing, shared driveways, rain gardens, and a narrower pervious concrete‐paver road. Weekly, flow‐weighted, composite samples of stormwater were analyzed for nitrate + nitrite‐nitrogen (NO3 + NO2‐N), ammonia‐nitrogen (NH3‐N), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total suspended solids (TSS). Monthly composite samples were analyzed for total copper (Cu), lead (Pb), and zinc (Zn). Mean weekly storm flow increased (600x) from the traditional watershed in the postconstruction period. Increased exports of TKN, NO3 + NO2‐N, NH3‐N, TP, Cu, Zn, and TSS in runoff were associated with the increased storm flow. Postconstruction storm flow in the LID watershed was reduced by 42% while peak discharge did not change from preconstruction conditions. Exports were reduced from the LID watershed for NH3‐N, TKN, Pb, and Zn, while TSS and TP exports increased.

Review of Stormwater Quality, Quantity and Treatment Methods Part 1: Stormwater Quantity Modelling

In this paper, review of stormwater quality and quantity in the urban environment is presented. The review is presented in three parts. This second part reviews the mathematical techiques used in the stromwater quality modelling and has been undertaken by examining a number of models that are in current use. The important features of models are discussed.

Impacts of Impervious Cover and Other Factors on Storm-Water Quality in Austin, Tex.

Changes in impervious cover result in changes in both urban water quality and quantity. The changes in storm-water quantity have been studied for many years; however, the impacts of impervious cover on storm-water quality are not as well understood. This paper examines the impacts of impervious cover on both storm-water quality loads and concentrations using data collected from 38 storm-water monitoring stations in Austin, Tex., between 1985 and 2005. The writer determined whether there was a significant relationship between impervious cover and the mean concentrations of several pollutants, including nutrients, metals, solids, and bacteria. In cases where no significant relationship existed, the data were examined to determine whether a difference in storm-water runoff quality from developed and undeveloped areas existed. A final comparison was performed using impervious cover and land use as independent variables and mean watershed concentrations of several common pollutants as dependant variables. This...

Effect of Aggregation of On-Site Storm-Water Control Devices in an Urban Catchment Model

Spatially distributed on-site devices such as detention tanks and bioretention are becoming more common as a means of controlling urban storm-water quantity and quality. One approach to modeling the cumulative catchment-scale effects of such devices is to resolve the catchment down to the scale of a land parcel or finer, and then to model each device separately. This involves computational and input data demands that may be impracticable, especially in planning or preliminary design stages of storm-water system design. To reduce these demands, the spatial resolution can be coarsened by aggregating land parcels and devices, but this may compromise model accuracy. The focus of this study was examination of the effects of aggregation on predictions of water quantity and quality (for a representative contaminant, total suspended solids) for detention, infiltration, and bioretention devices. A detailed model for urban storm water improvement conceptualization simulation was set up for a 0.83 km2 catchment wit...

Predictive Modeling of Storm-Water Runoff Quantity and Quality for a Large Urban Watershed

A predictive model for storm-water runoff was implemented on a GIS platform based on the unit area loading method and Browne’s empirical relation for soil characteristics for the Upper Ballona Creek Watershed in Los Angeles. The heterogeneity of the watershed was quantified by dividing it into many small subareas and applying lumped parameters for each. Characterization of total pollutant load by land-use types to total loads was achieved through zeroth-order regularization and limited memory Broyden–Fletcher–Goldfarb–Shanno bound constrained optimization techniques. Relative form was used in the objective function to compensate for strong contributions of high magnitude variables. Model predictions showed reasonable agreement with pollutant loadings, using Zn as an example, measured at the mass emission site at watershed mouth. The predicted runoff volumes using the developed quantity model were in good agreement with the data and had R2 of 0.86. The RMS error of the quality model was 9 kg , which is low...

Sustainable use of stormwater for irrigation case study: Manly Golf Course

Sustainability has become an increasingly used term, but what does it mean in terms of practice. This research will look at the harvesting of captured stormwater for the irrigation of urban playing fields and what the implications are for catchment hydrology, local community, and local council. This research aims to identify, understand and determine the catchment conditions that may hinder the stormwater quality and quantity for capture and reuse, as well as determining whether the stormwater harvesting will be sustainable. Research methods for this project will include systemic analysis in order to further investigate the assumptions being made in the study. Manly Golf Club has relied on groundwater extraction supplemented by potable supplies for irrigation, however potable supplies are no longer available. It has been proposed to provide irrigation supplies from stormwater via onsite storage and groundwater recharge. Monitored stormwater entering the Golf Course from the adjacent Cemetery Creek sub-catchment for pollutants, have indicated that it may be suitable for irrigation with treatment and may reduce problems generated by overuse of groundwater. The proposal will provide environmental benefit through reduced pollution loads being discharged directly to receiving waters and cessation of use of potable supplies by the Club. Social and economic benefits are expected to be gained and will be monitored as part of an ongoing research program.