World Environmental and Water Resources Congress 2016: Water, Wastewater, and Stormwater and Urban Watershed Symposium

Cities with combined sewer systems must comply with Environmental Protection Agency (EPA) regulations which mandate control of stormwater discharges and prevention of combined sewer overflows (CSOs). Mimicking natural hydrologic processes, green infrastructure (GI) practices manage stormwater at the source, reduce CSOs and may provide long-term solutions to urban challenges. In this study, a holistic approach is applied to monitoring, developing and demonstrating high-performing next generation volume reduction GI practices through a partnership between Villanova University and the Philadelphia Water Department, funded via the EPA STAR grant program. Data collection is underway at multiple GI sites in Philadelphia with the goals of performance evaluation and informing future design, and with targeted focus on both maximizing and further understanding the infiltration and evapotranspiration components of the water budget. Preliminary results show that these systems have the ability to capture more runoff than previously thought. The research presented in this paper also identifies challenges and appropriate solutions associated with monitoring in the urban environment.

Urban flood is one of the biggest environmental problems of the planet. It generates high negative impacts of various kinds: social, environmental, and economic. These problems grow exponentially in megacities, since the disorderly occupation of land, coupled with the size of the population, make it extremely complex to control and to manage. Structural measures for flood control are not enough, the city needs to deploy a number of non-structural measures such as a flood warning system. This system aims to provide real-time occurrence of floods that may cause impacts in several areas of the city. These forecasts trigger a series of actions for civil defense, firefighter, traffic control, social support, and other entities. The flood warning system of the São Paulo metropolitan region, Brazil, called SAISP system, installed a set of weather radars and telemetry networks, as well as a decision support system (DSS), which generates a set of forecasting bulletins. Several public organizations and press receive these bulletins in real time. The results obtained in the last years of operation show that SAISP is a high efficient system, bringing immense benefits to the population of the São Paulo metropolitan region. This paper presents the major technical challenges faced by SAISP in the last years of operation and shows some of their latest results, especially of the mathematical models used to forecast floods in many areas of the city.

Roads, highways, and developed land can alter hydrologic pathways, cause erosion and pollution to nearby waters. Best management practices (BMPs) are commonly used to reduce adverse effects of post-construction runoff (e.g., peak flows and runoff volumes). By applying the personal computer stormwater management model (PCSWMM), this study took an idealized catchment area approach to evaluate the performance of linear BMP alternatives for retaining the first inch of stormwater runoff from highways and roads in Illinois. Various combinations of BMPs consisting of vegetated filter strip, bioswale, and/or infiltration trench were analyzed. Two types of grass covers were considered: prairie grass and turf grass. One-inch of 24-h accumulated rainfall was used for all of evaluated scenarios. The sizes and dimensions of the evaluated BMPs were extracted from Illinois Department of Transportation (IDOT) projects. Stormwater runoff from combined post-BMP construction under the two different grass covers were compared to pre-BMP construction under the condition of bare soil cover. Results indicated that runoff reduction ranges from 96 to 99% for combination of vegetated filter strip-bioswale, 89 to 100% for vegetated filter strip-infiltration trench, and 100% for bioswale-infiltration trench. Results also showed that prairie grass cover is more effective than turf grass in reducing runoff from various soil types. Findings from this study can benefit DOT to develop cost-effective solutions to manage storm runoff from roads and highways.

Flood models were developed using a rapid 2D simplified-hydraulics solver for four watersheds located within Radnor township. These urban watersheds vary in size from 6.1 to 77.2 km². A range of design events were simulated in the four watershed models in order to understand the variations in extent and severity of flooding for different storm magnitudes and durations. The design events and their corresponding rainfall depths, which were based on point precipitation frequency estimates at Villanova, PA, range from 1.19 in. for the 1-year/1-h event to 7.61 in. for the 100-year/24-h event. Use of the flood modeller FAST simplified-hydraulics solver enabled a quick representation of the location, extent and severity (depth grid) of known flood locations and identification of additional areas that may be prone to further flooding. High flood risk areas were ultimately chosen based on the streets and parcels that contained the most significant flooding based on the modeled flood depth grid results. The simulated flood extents corresponded with the majority of the township’s known flooding areas. Several of the additional areas identified to be prone to flooding based on model results were also confirmed by the township. The high flood risk areas determined by the modeling are currently being investigated in the field. Concept designs, ranging from increased conveyance capacity to implementation of green infrastructure, will be developed to alleviate flood risk in these areas.

Increasing urbanization augments impervious surface area which results in increased run off volumes and peak flows. Low impact development (LID) approaches present a decentralized alternative for sustainable urban stormwater and provide water conservation opportunities. They also provide a wide array of ecosystem services and foster community building by enhancing neighborhood aesthetics, increasing property value, and providing shared green spaces. While projects involving sustainability concepts and environmental design are favored in privileged communities, marginalized communities have historically been located in areas that suffer from environmental degradation. Underprivileged communities typically do not receive as many social and environmental services as advantaged communities. This research develops a participatory decision-making approach to address environmental justice for marginalized communities and explore LID strategies at the watershed scale for improving hydrological performance and mitigating flooding. Focus groups are designed and conducted to solicit input from community members, stakeholders, and community advocates about sustainable stormwater management alternatives. Input will be used to develop LID strategies that meet community goals, such as maximizing the provision of ecosystem services, providing water conservation opportunities, and fostering community building. A hydrologic/hydraulic stormwater modeling system will be developed using HEC-HMS and SWMM to simulate the stormwater impacts of rain water harvesting systems, green roofs, and bioretention cells. This approach will be implemented for a marginalized community within the Walnut Creek Watershed in Raleigh, North Carolina. On-going research will seek further feedback from the community about LID strategies that are developed using the hydrologic/hydraulic modeling system to assess preferences about LID decisions and tradeoffs among design goals.

Rain gardens have proven to be an effective means to control stormwater; thus, in Pennsylvania’s Stormwater Best Management Practice’s Manual, rain gardens are the preferred stormwater control measure (SCM). Currently, volume capture in Pennsylvania is calculated using a static bowl equation that does not include the dynamics of infiltration and evapotranspiration (ET). In addition, many states’ design guidelines for rain garden soil mixes are often restrictive and vague. The goal of the work described in this paper is to develop guidelines for soil mixes that consider the balance of infiltration and ET using bench-scale experiments at Villanova University. A total of twelve discrete weighing lysimeters were filled with soils that span the lower portion the USDA classification triangle. The lysimeters were divided evenly into two flow path configurations: vertical 46 cm deep columns and horizontal 20 cm deep boxes at a 2.5% slope. Both lysimeter configurations utilized loamy sand, sandy loam (typical rain garden mix in PA), loam, silt loam, and clay loam soils. Switchgrass was planted in all but two lysimeters to provide a non-vegetated control with sandy loam soil. Runoff was added into the lysimeters during rainfall events to simulate actual rain garden performance and the lysimeters were weighed daily for two weeks after the event. Preliminary results of five storm simulations provide an average ET rate of 3.3 mm/day for the vertical lysimeters and 2.6 mm/day for the horizontal lysimeters. In the vertical configuration the silt loam soil produces the most volume removal through ET at 44% of the total volume removal with an average ET rate of 4.2 mm/day. In contrast, the loamy sand soil produces the least volume removal through ET at 25% of the total volume removal.

Urban stormwater runoff can promote eutrophication by discharging excessive nitrogen loads into downstream surface waters. Conventional stormwater biofiltration systems are inefficient in removing nitrate; however, a submerged denitrifying biofilter containing an electron donor (e.g., wood chips) can be incorporated into these systems to enhance denitrification. This study presents a nitrate removal model for denitrifying stormwater biofilters. This model is compatible with existing stormwater modeling software (i.e., Environmental Protection Agency Stormwater Management Model version 5.1). Processes that were incorporated into the model include water mixing, wood chip dissolution and a denitrification kinetic model that includes the effects of bio-available organic substrate and dissolved oxygen concentration on denitrification. The model was calibrated and validated with experimental data using thirty design events with different storm duration, antecedent dry conditions, hydraulic loading conditions, influent nitrate concentrations and biofilter depth. The model accurately predicted nitrate mass removal efficiencies that were within 10% of the results of each experimental event. The model was validated with a high Nash-Sutcliffe efficiency coefficient (0.80) and coefficient of determination (0.85). This denitrifying biofilter model provides a practical tool for engineers to quantify nitrate removal as a function of biofilter characteristics as opposed to assumed percent removal efficiencies. Recommendations for future research include validating the model with field data and developing a total nitrogen removal model for denitrifying biofiltration systems.

Focusing on the neighborhood where the Village of Arts and Humanities is, we have developed, evaluated, and tested a method for incorporating community input regarding ancillary green infrastructure (GI) benefits into a multi-objective GI optimization model. The model adapts the Stormwater Investment Strategy Evaluation (StormWISE) model for use in urban settings where the community interests are expressed using additive utility functions with weights elicited from community workshops. The ancillary benefits quantified in the case study are the highest priority benefits identified by the GreenPhilly Community Advisory Research Board (GCARB) though exercises created for the workshops. Four weighting methods are compared to assess consistency and sensitivity of the results.

As introduced at the 2014 EWRI Congress, the city of Austin undertook a rigorous planning and modeling study to evaluate decentralized, green infrastructure approaches for neighborhood flooding and other watershed management issues. This study, which was recently completed, provided rare opportunities to perform model calibration of a small urban watershed, conduct detailed two-dimensional modeling of overland flow, and evaluate various potential control alternatives. The goal of this study was to evaluate whether alternative flood control approaches, based on decentralized controls, could be more cost-effectively implemented than traditional approaches while providing additional benefits such as reduction in pollutant loads and channel erosion, increase in water supply, and neighborhood improvements. More recently, additional model iterations were completed and the monitoring record was expanded to include major rainfall events. The study concluded with development and evaluation of a preferred green/grey hybrid option and associated implementation guidance. The preferred approach involves a combination of green infrastructure retrofits for hydrologic source control (implemented through public projects and private property incentives) combined with strategic traditional drainage improvements to address capacity limitations. The combination of elements allowed the frequency of critical flooding to be reduced within the watershed by 5 to 10 fold and structure flooding to be nearly eliminated up to the 25 year peak event, while maintaining no increase in peak flow at the watershed outlet. This has significant cost savings compared to the traditional approach, as it avoids the need for a series of upgrades to the downstream conveyance system. This paper provides a summary of final study findings and highlight the findings that are applicable to other municipalities, land developers, and stormwater professionals.

Municipalities are turning to green infrastructure (GI) as an attractive solution for combined sewer overflow (CSO) control. Given the myriad combinations of GI implementation options, decision makers need tools to optimize investments. Multiobjective models hold significant promise for developing GI investment portfolios, but need to be developed and tested under real world conditions. We present models for estimating GI costs and for optimizing deployment of GI practices applied to a Piedmont sewershed in Philadelphia’s CSO area.

Green infrastructure (GI) is typically implemented with static flow control devices. More recently, actively controlled GI concepts have been developed (e.g., OptiRTC, RainGrid) and applied to demonstrate that additional benefits (e.g., lower runoff volume, cost savings) can be accomplished with different operating strategies. The objective of this study was to evaluate the potential long-term performance of several actively controlled GI technologies implemented throughout a mixed-land use neighborhood. Detailed USEPA SWMM models of the drainage area and a spreadsheet tool were developed for conventional, GI and controlled GI scenarios, and a separate spreadsheet tool was developed to simulate and test different operating strategies. Model results indicate that the GI implementation results in an overall runoff reduction and peak flow reduction of 54.7% and 26.3%, respectively. Controlled GI offered a small incremental improvement, but was able to maximize the use of existing infrastructure and minimize the negative effects caused by sewer overflows.

Gray stormwater infrastructure has a specific hydraulic capacity, which tends to get undersized when receiving the incremental input flow rate coming from new developed areas or from changes in the land use. Implementing sustainable urban drainage systems - SUDS in consolidated urban watersheds is a feasible alternative that allows managing stormwater runoff combined with the traditional infrastructure. However, its use on a massive scale in cities is a challenge for urban planning. This article shows the results from a research oriented to identifying potential areas for applying SUDS as a support for urban planning in order to define strategies for potential application of rain gardens, permeable paving, storage tanks and green roofs by using models from GIS. A case study was conducted to 10 watersheds in Barranquilla (Colombia), which has severe stormwater issues related to runoff volume and peak flow, and where SUDS may be a feasible alternative for runoff management. Physical conditions of the watershed, such as the type of soil, the water table and slope, socio-economic characteristics, land use and other environmental variables were analyzed in a decision making framework model implemented in GIS. The results allowed defining criteria for prioritizing by type of SUDS and location area in order to help ensuring their general effectiveness on the urban watersheds.

Philadelphia Water’s Green City, clean waters program outlines a vision for large-scale implementation of green stormwater infrastructure (GSI) to reduce stormwater-based demand on the combined sewer. A GSI monitoring plan has been developed as a component of the comprehensive monitoring plan required by Philadelphia water’s agreement with the Pennsylvania department of environmental protection. A brief overview of the continuous water level (CWL) monitoring network and its tools and collection methods is presented. Qualitative and quantitative performance evaluation via simulated runoff tests (SRTs) is discussed. The methodology and suitability of each test type are explained through real world examples of each. Quantitative SRT data are also used to calibrate a model that predicts infiltration rates and helps calculate water budgets. Data analysis infrastructure is discussed. Philadelphia Water’s GSI monitoring group uses R (R core team, 2015) and related technologies for automated quality assurance and quality control of large amounts of CWL data. The R infrastructure allows for ease of visualization, report writing, and malfunction detection. Interoperation with a sophisticated R-based analysis tool called PilotDB allows for tracking performance and compliance in a cloud-based dashboard. The merit of R-based analysis over manual spreadsheet-based analysis is illustrated through these topics.

Philadelphia Water (PWD) has entered its fifth year of the Green City, Clean Waters program, which focuses on implementing green stormwater infrastructure (GSI) to manage runoff. PWD is developing an evaluation and adaptation plan (EAP) to document implementation progress to date. PWD is monitoring constructed GSI systems to assess observed performance compared to design assumptions and expected performance. Due to the large scale of Green City, Clean Waters, the monitoring plan focuses on gathering long term data from many systems, rather than intensive monitoring at a few sites. Each system has two data inputs: a continuous water level logger within the system and gauge-adjusted radar rainfall data. These data are processed with PilotDB, a cloud-hosted data analysis tool developed with the Shiny web application for R. Data are run through a time step-based, mass balance algorithm to develop an estimated water budget for each event at each site. An expected water level time series is developed using knowledge of the design configuration, material properties, and pre-construction geotechnical investigation data. Time series plots for observed and expected water levels are compared in PilotDB, and the interface allows the user to categorize events based on system response. Performance metrics are established for each system, and used to analyze the effect of design parameters on the functionality of each system. Analysis protocols executed in PilotDB and by PWD staff are demonstrated through case studies and summary statistics. Integration of design parameters, as-built conditions, monitoring, and maintenance information into PilotDB analyses is described.

As stormwater permits and design manuals are updated throughout the United States, design standards have tended to become more prescriptive for biofiltration (bioretention with underdrains), including limitations on filtration rate, footprint, and other factors. Recognizing the need for innovation in biofiltration design, the Los Angeles County MS4 Permit (Order No. R4-2012-0175) (MS4 Permit) provided a pathway for the approval of alternate biofilter designs that provide equal or better pollutant load reduction compared to the standard specification. In response, an analysis was conducted to compare Filterra performance to conventional biofiltration. Using water quality performance data from field studies and hydrologic modeling of system capture efficiency and volume reduction, we identified site conditions and sizing criteria under which Filterra systems would provide equivalent performance in comparison to conventional biofiltration BMPs in the Los Angeles region.

The city of Barranquilla in Colombia has one of the major stormwater management issues in the world. Due to the lack of a stormwater drainage system in more than 90% of its urban area, the runoff flows on the streets during rain events with dangerous flow rates of up to 100 m3/s for a 50-years return period. The permeable areas are little and the steep slopes of the city cause supercritical flow and flash floods on many streets with high velocities. This has negative consequences such loss of human life, damage to infrastructure, and economic losses. A 1D model was setup in PCSWMM to assess the flow rate, velocity and hazard levels on the streets for different rainfall events. This model was performed considering a process of characterization and calibration of the drainage conditions of the city, including land survey and field measuring by using rain gages and flow gauges installed in the monitoring system PLUVIAL.CO (www.pluvial.co). The hazard levels results were compared with the safety criteria for people (1.2 m²/s), obtaining up to 6 m²/s from recorded events in 2014 and 20 m²/s for events with 100-year storm. The hazard, velocity and depth maps are presented in the article.

To comply with Oregon Department of Environmental Quality (ODEQ) requirements for a National Pollution Discharge Elimination System (NPDES) permit, a mixing zone dilution and modeling study was conducted for a municipal wastewater multiport diffuser discharge into the Willamette River. A field dilution study was conducted to observe and measure ambient and discharge conditions at the site. The discharge location is relatively shallow and is not density stratified or tidally influenced. Rhodamine WT fluorescent tracer dye was injected into the 5 m long, 4-port multiport diffuser discharge of 1.1 MGD to measure downstream mixing zone behavior of the effluent plume. Measurements of ambient bathymetry and velocity were taken with a boat mounted acoustic Doppler current profiler (ADCP) unit. Measurements of dye concentrations were taken using a boat mounted conductivity temperature depth (CTD) sensor fitted with a submersible Rhodamine WT sensor. CORMIX v9.0 mixing zone model predictions were compared with and verified by field dye dilution measurements. CORMIX model predictions were in good overall agreement with measured dye dilution data. Subsequent modeling was completed to determine dilutions from the newly installed multiport diffuser for various critical low ambient flow conditions to reflect extreme conditions and for regulatory compliance. Overall the newly installed multiport diffuser increased the effluent plume dilutions by about 6 times within the near-field and by about 2 times at the far-field when compared to the previous single port discharge configuration.

The solid by-products generated in treatment of municipal wastewater are generally dewatered to 16 to 30%, which is dependent upon effectiveness of chemical conditioning and dewatering. Current mechanical dewatering of municipal wastewater solids include usage of belt filter presses (BFPs) or centrifuges for most part, however, screw or rotary fan press’ low-energy dewatering of biosolids are upcoming. Dewatering of municipal wastewater biosolids is critical in that solids’ conditioning and dewatering are two (2) expensive steps. Several municipal solids’ dewatering results showed the conditioning polymer use can range between ten (10) and twenty (20) pounds per dry-ton of solids and, however, some biosolids based on the stabilization techniques upstream, may consume higher polymer for conditioning. Author has designed and conducted pilot and field scale biosolids dewatering studies with the application(s) of various conditioning polymers. The municipal operators are challenged with complex situations of selection of chemical conditioner, mixing with solids, and the effective operation of mechanical sludge dewatering unit(s). This paper included a critical discussion of characteristics of biosolids for dewatering, use of chemical conditioners, mechanical sludge dewatering methods, and field data on selected mechanical dewatering techniques.

Selenium is toxic to aquatic life at very low levels and can also be harmful to human health. Anthropogenic sources of selenium are wide spread including electronic and photography, glass manufacturing, pigments, additives for metal processing, copper refining operations, fossil fuel combustion, petroleum refining, and agricultural drainage waters in the Western United States. This study investigates selenium removal by microbial reduction with a pure culture of selenium-reducing bacterium Escherichia coli strain EWB32213 isolated in our laboratory from a coal slurry pond. Environmental factors evaluated include temperature, pH, and selenium concentration with optimal conditions observed at pH 7 and 30°C. A two-stage reduction process, from selenate to selenite, followed by selenite to elemental selenium and subsequent precipitation was observed in the batch culture. The reduction of selenite to elemental selenium in the second stage was found to be the rate limiting process with reduction rate significantly lower than that in the first-stage.

As a stormwater management technique, rain gardens can reduce runoff volume and retain contaminants such as metals found in urban stormwater runoff. Due to organic material in rain gardens such as plants, mulch, and compost, however, rain gardens have been shown to release dissolved phosphorus, which is typically targeted for removal from stormwater. As a result, rain gardens can act as a source of dissolved phosphorus and cause a corresponding increase in the dissolved phosphorus concentration in runoff. This project assesses the performance of an iron-enhanced rain garden with regards to its ability to retain dissolved phosphorus. Studies have shown that iron-enhanced sand filtration has the ability to remove over 90% of dissolved phosphorus from stormwater runoff. A new rain garden design incorporating a layer of sand mixed with iron shavings at 5% (by weight) beneath typical rain garden media was tested under laboratory conditions for its ability to retain dissolved phosphorus. Performance was compared to a control rain garden that contained a layer of only sand beneath typical rain garden media. Preliminary results indicated that the iron-enhanced rain garden consistently retained approximately 90% or more of the dissolved phosphorus load after more than 61 m of water had infiltrated. The control rain garden initially retained over 50% of the dissolved phosphorus load. However, after the same depth of infiltrated water, dissolved phosphorus retention dropped significantly and ultimately became negative.

Stormwater bioinfiltration systems are widely used in urban areas to reduce stormwater runoff volume, peak flows, and stormwater pollutant loads reaching receiving waters. Appropriate hydraulic characteristics of the filter media, including treatment flow rate, and water contact time, are important considerations for the selection of the media. This paper describes a series of tests conducted using a variety of biofilter media to determine factors that affect their infiltration rates. Laboratory tests examined the infiltration rates of these materials subjected to various levels of compaction and sand amendments. A series of sand mixtures were also prepared and tested that represent a wide range of median particle sizes and uniformity coefficients and were also subjected to various levels of compaction. The effects on the infiltration rates by adding organic matter to selected media mixtures were also examined. The laboratory tests indicated that compaction has a significant effect on the infiltration rates; however, amending the sand mixtures with peat reduced the degraded flow rate effects associated with compaction.

Stormwater poses flooding and pollution hazards in urban areas. The impacts of polluted urban stormwater have given rise to low impact development (LID). The Avalon Green Alley Network: LID Demonstration project is a joint partnership between the City of Los Angeles Bureau of Sanitation, the trust for public land, the council for watershed health, the coalition for responsible community development, and the Los Angeles Conservation corps to develop LID design interventions for stormwater infiltration in South Los Angeles. The project is located in public alleys right-of-way in high-density neighborhood blocks. The alley is bordered primarily by residential units and is adjacent to a schools, parks, and commercial building with parking lot. The project slows, infiltrates, and retains stormwater on site, capturing runoff from the intersecting streets catch basin intercepts, using dry well chambers, replacing asphalt with permeable surfaces, percolating stormwater, and providing underground storage. Runoff drains toward interlocking pavers to allow stormwater to flow into an underground infiltration trench for treatment. Overflow from these trenches then flows to a dry-wells system where it infiltrates into the ground. Water quality monitoring includes groundwater motoring wells, flow meters, and series of level-loggers have been installed in the alley to quantify water quality and water-supply benefits. In addition to water quality components, the project has other benefits for the community, including the growing of vines and espalier trees, artistic paving, and artwork in the form of poetry.

Development of low-cost, self-sustainable, and easy-to-operate sewage treatment reactors for rural areas of India for non-potable reuse is an earnest need-of-the-hour. Three low-cost sewage treatment systems: vermifiltration (VF), soil biofilter (SBF), and sponge-filled trickling filter followed by SBF (SPTF-SBF) were studied for removal of COD, turbidity, and transformation of N and P, at hydraulic loading (HLR) varying as 0.5, 1.0, and 1.5 m/day. All the reactors achieved almost complete removal of turbidity and increase in PO₄-P in the effluent due to decomposition organic matter. VF1 and VF2 (containing 36 and 72 g earthworms, respectively) achieved 88–94% and 90–95% COD and 58–80% and 30–90% NH₄-N removal, respectively, with removal decreasing slightly with increase in HLR. The earthworm massin VF decreased with time indicating that an additional source of food may be required for survival and growth of earthworms. SBF achieved 86-91% COD and 41-60% NH₄-N removal. The performance of VF and SBF was inconsistent due to chocking of soil layer with SBF chocking more frequently. It was observed that decrease in nitrification and PO₄-P formation indicated onslaught of chocking in VF and SBF. Overall COD removal of 95-96% and almost complete nitrification was obtained in SPTF-SBF, independent of HLR. The performance of SPTF-SBF system was consistent, free of any chocking, and did not require any supervision. Increase in PO₄-P (~48%) in the effluent of SPTF-SBF was the highest among the three systems. The nutrients (NO₃-N, PO₄-P) were retained which suggests that effluent of SPTF-SBF system can be reused for irrigation.

A geyser in a stormwater (SW) and combined sewer system (CSS) is a high frequency oscillatory release of a mixture of gas and liquid that occurs at vertical shafts and other relief points. The oscillating jet of gas-liquid mixtures may reach a height of the order of a few to tens of meters above ground level. A considerable number of hypotheses were formulated for the causes of these geysers. Using actual geyser formulations, it is not clear how to predict a large geyser height as observed in actual stormwater and combined sewer systems. This paper describes a new theory on the causes of geyser occurrence and presents a simplified model for quantifying geyser eruption based on simultaneous exsolution of multiple gases. This model was applied to a geysering event in a stormwater collection system in Minneapolis.

The Maheshtala is one of the century old textile clusters in India. Due to availability of cotton and skilled human resources in West Bengal, textile units set up rapidly. At present about 700 units are operating in Maheshtala region covering Chatta, Chatta bazaar, Kalikapur and Mahishpota and other adjoining areas. The effluent discharged from these units is estimated at 20,000 kl/day. The huge quantity of water drawn from the underground resources for textile processing, bleaching, dyeing, printing, etc. Effluents thus produced from such operations are directly discharged to the adjoining Chatta Canal and nearby land. The study revealed that the chemical parameters like suspended solids (926 mg/L), total dissolved solids (6,410 mg/L), chemical oxygen demand (1,824mg/L), biochemical oxygen demand (608 mg/L), chromium (0.03mg/L), and lead (0.43 mg/L) of raw effluent exceeded the maximum permissible discharge limits laid down by Bureau of Indian Standards and WHO standards. The degraded surface water of canal overflows to the adjoining agriculture land. The surface water quality is not suitable for domestic use, agriculture and aqua cultural production. The major cross-section of the people inhabiting in those areas and the persons occupationally exposed to those trace metals have become affected in many pathological conditions like gastrointestinal disorder, high blood pressure, ulceration in GI region, cancer, etc. As an immediate remedial measure 3–4 advanced common effluent treatment plants (CETP) with a capacity of treating of 500–600 kl/day each being technically feasible and financially viable are required to be installed for altogether 250 tiny and small scale textile bleaching and dyeing units in an industrial park within the cluster.

This project is a component of a U.S. Environmental Protection Agency Great Lakes Restoration Initiative grant awarded in 2014 to Detroit Water and Sewerage Department (DWSD). The project is a collaborative effort between DWSD, Lawrence Technological University, Detroit Economic Growth Corporation, several non-profit entities and private consulting firms. It is important for green infrastructure retrofit projects to estimate volumetric reduction, especially in CSOs as is the case for this project. An estimating approach is common because of the difficulties associated with accurately modeling green infrastructure. As such, the “success” or cumulative effect of green infrastructure implementation is often estimated and not measured. There are four methodologies currently being used for predicting stormwater runoff for this project including EPA SWMM 5.1, EPA Stormwater Calculator, spreadsheet based NRCS curve number (CN) method, and the green values calculator. Methods based on the CN Method are event-based models and provide volume reduction for specific sized storm events. Other hydrologic models, like SWMM, are capable of continuous modeling and more accurately determine the performance of green infrastructure in terms of peak discharge and volume reduction. These various modeling methods are being compared at both the lot scale and neighborhood scale both with each other and ultimately flow monitoring data being collected within the combined sewer and street gutter systems from both real and synthetic rainfall simulations on the site. The validated models will then be used to more accurate predict flow from existing and redeveloped green infrastructure conditions.

In booster chlorination, the chlorine is reapplied at strategic locations to achieve the uniform chlorine concentration within the water distribution network. The only source chlorination provides uneven residual chlorine at various locations in the network covering large area. The critical nodes are identified by developing response coefficient matrix using EPANET. EPANET is used to simulate the flow hydraulics and residual chlorine in the network. It uses first order reaction kinetics to simulate the chlorine decay. At selected locations chlorine mass rate range provides solution space for particles in PSO. The objective is to minimize the total mass rate of chlorine application in the network. The minimum residual chlorine and its maximum values are maintained by introducing penalty terms. Distribution network of Vadodara City area of India is selected for the application of model. The junction nodes of network feeding micro network to consumer end are monitored for residual chlorine. Maximum two booster stations are proposed to be selected and the coupled model is used to find their locations and mass rate of chlorine injection in conjunction with the source chlorination mass rate. The residual chlorine concentrations are obtained for optimum solution and results are compared with that obtained for conventional source chlorination. It is observed that reduction of more than 30% is achieved in booster chlorination strategy as obtained by optimization model. The suggested strategy also results in uniform distribution over conventional approach. The reduction in chlorine in the network also helps reducing disinfection by products.

Reactive azo dyes constitute a major fraction of all dyes manufactured in India. It is reported that out of ~0.7 million t synthetic organic dyes manufactured worldwide, ~15% of the dyes end up in environment causing severe water pollution. The present study demonstrates a simple route for synthesis and application of plasmonic Ag^o/AgBr photocatalyst for rapid decolourization of an azo dye RB5 under visible light. The TEM images of Ag^o/AgBr showed the particle size ranging from 7 to 28 nm. The influence of molar ratio of Ag:Br, irradiation time for formation of Ag^o, initial pH, dye concentration, and dose of photocatalyst on decolourization was studied. Extent of RB5 removal was almost independent of initial pH values of 2.0, 7.0, and 9.0. 76.7%, 96.7%, 97.9% decolourization of initial 50 mg/L RB5 with corresponding 1^st-order reaction rate constants as 0.069, 0.160, and 0.149 min^-1 were obtained at Ag:Br molar ratio of 1:1, 1.25:1, and 1.5:1, respectively, for 60 min of photocatalysis. Irradiation time for formation of Ag^o during synthesis influenced decolourization. Decolourization efficiencies at 0, 10, 20, and 30 min irradiation were 84.26%, 95.7%, 98.1%, and 94.9%, respectively, at Ag:Br molar ratio 1.25:1. The rate and extent of decolourization decreased with increasing initial dye concentration and increased with increase in photocatalyst dose from 0.3 to 0.5 g/L. However, further increase in dose did not improve decolourization efficiency any further.

The EPA Stormwater Management Model (SWMM) for the city of New Bedford’s collection system is uniquely complex. It is highly detailed and thoroughly calibrated to baseflow, runoff, groundwater, and snow processes. The city’s combined collection system, which serves a population of 104,000, dates to the 19th century. This aging, complicated collection system includes 71 overflow weirs, 11 pump stations, and 9 control gates. Beginning in 1990, New Bedford has dedicated $250 million to system improvements, reducing average annual combined sewer overflow (CSO) from 3.1 billion gal. in 1990 to 284 million gal. as of 2012, a 90% reduction. Since 2012, New Bedford has committed an additional $11 million to continue to reduce CSO. Today, the city is implementing programs for sewer separation in flood-prone areas, detection and elimination of illicit discharges, and reconstruction of pump stations. For the current CSO abatement program, the model was expanded to capture recent system improvements and add detail in areas that were previously coarsely represented. The model was updated with treatment plant control rules calibrated to SCADA, pump station capacities calibrated to actual performance, and calibration to 2013–2014 flow monitoring data. Simulation of an average five-year period shows that the recent system improvements have further reduced CSO volumes from 2012. New Bedford now discharges an average of 220 million gal./year, a 20% reduction from 2012. The model is currently being used to plan further improvements to the system and assess potential green stormwater infrastructure.

Optimal design of water distribution networks involves an evaluation of different aspects such as economic and technical analysis, mechanical and hydraulic issues, and population-based strategies. These objectives often conflict, to an extent that finding the optimal solution for one of those objectives reduces the other objective’s utility. This paper presents an approach to select an optimal design between three pre-specified scenarios that accounts for both economic and technical issues to supply the required water demand to customers, and also satisfy decision makers’ criteria and meet the design purposes for Darakeh neighborhood in Tehran, Iran. WaterGEMS software that contains powerful GIS-based solution for efficiently modeling, managing, and protecting valuable resource water, was used to find a management solution and design an optimal water-supply system. Consequently, based on economic and technical scoring, one of the considered scenarios was evaluated as the best option for the water distribution network of the study area.

On October 29, 2012, Superstorm Sandy brought devastation to the east coast. Storm surge and flooding affected a large swath of the State of New Jersey. Along with the homes and businesses, critical public infrastructure including water and wastewater treatment facilities was inundated. One such entity that was impacted was the Kearny Municipal Utilities Authority (KMUA). Two of KMUA’s pump stations were flooded on October 29th and on October 30th their road to recovery started. Beginning with initial operational restoration efforts, their journey has included but is not limited to design approaches to increase resiliency at these facilities and obtaining funding from various sources for construction. Recovery efforts are funded by FEMA the optimum hazard mitigation solutions for the KMUA’s facilities were investigated. Effective communication between the owner, its operators, engineers, regulatory, and funding agencies is paramount to successful completion of the recovery efforts in a timely manner. Resiliency design options to fit both the needs of the facility and work with in the operational goals of the organization were evaluated with the owner.

Using smoothed particle hydrodynamics (SPH) method the hydrodynamic equations can be solved by interpolating a continuous fluid with particles. Key advantages for the application in wastewater treatment (WWT) are the intrinsic support of free surfaces and the exact handling of advection. The combination of SPH as hydraulic model with the activated sludge models (ASM) enables a spatially resolved calculation of the biokinetic processes. The proposed approach is to assign biokinetic concentrations to SPH particles such that the transport processes can be modelled in detail. Thereby, it is possible to quantify the effects of the hydraulic mixing on the biokinetic processes for unsteady flow conditions. In this paper, the SPH activated sludge engine (SPHASE) software is introduced. SPHASE is a self-developed and freely available tool where the method discussed above is implemented to support the design and operation of WWT plants. A specifically optimized two dimensional SPH solver uses graphics devices to cope with the high computational demand such that real-time simulation performance is attained. Spatially resolved biokinetics are computed per particle using a neighborhood weighted ASM function, different biological initial conditions can quickly be evaluated on top of the existing hydraulic simulation. The results are graphically visualized in the user interface to analyze the hydrodynamics and the corresponding biokinetic evolutions.

Improving the hydraulic performance of waste stabilization ponds (WSPs) is an important management strategy to not only ensure protection of public health and the environment, but also to maximize the potential reuse of valuable resources found in the treated effluent. To reuse effluent from WSPs, a better understanding of the factors that impact the hydraulic performance of the system is needed. One major factor determining the hydraulic performance of a WSP is sludge accumulation, which alters the volume of the pond. In this study, computational fluid dynamics (CFD) analysis was applied to investigate the impact of sludge layer geometry on hydraulic performance of a facultative pond, typically used in many small communities throughout the developing world. Four waste stabilization pond cases with different sludge volumes and distributions were investigated. Results indicate that sludge distribution and volume have a significant impact on wastewater treatment efficiency and capacity. Although treatment capacity is reduced with accumulation of sludge, the latter may induce a baffling effect which causes the flow to behave closer to that of plug flow reactor and thus increase treatment efficiency. In addition to sludge accumulation and distribution, the impact of water surface level is also investigated through two additional cases. Findings show that an increase in water level while keeping a constant flow rate can result in a significant decrease in the hydraulic performance by reducing the sludge baffling effect, suggesting a careful monitoring of sludge accumulation and water surface level in WSP systems.

Sanitary sewer overflow (SSO) is the discharge of wastewater from the collection network into the environment. The EPA estimates that up to 75,000 SSO events occur in the U.S. each year. SSOs can occur during dry or wet weather and are significant environmental and public health hazards. One of the main causes of SSOs is excessive rainfall derived inflow and infiltration into the network. This study applies a multi-objective genetic algorithm (MOGA) to identify near optimal solutions to minimize SSO occurrences and costs. The tested approach enhances the flow capacity of the collection and conveyance system by pipe diameter increase. The approach is tested in a 5.9 mi² sewer network, located west downtown of San Antonio, Texas. This network is 16.8 mi long, divided into 459 pipe segments, and is currently monitored by 3 flow meters. The hydraulic behavior of the network was modeled using the EPA SWMM. The MOGA approach characterizes the trade-off between SSO reduction and cost, and provides stakeholders a better understanding of the system and flexibility in the decision making process to eliminate SSOs.

This paper presents the integration of Weap and Qual2k models for the simulation of water quality scenarios in the Descoberto River Basin as a consequence of the population growth in the southwest of the Federal District in Brazil. The high growing rates of urban areas in the region add stress to the water supply and sanitation systems jeopardizing the water quality in the Descoberto River Basin, where most of the waste water treatment plants (WWTPs) are located. Scenarios of population growth and different WWTP’s efficiency were built in WEAP from 2010 to 2030 to evaluate the impacts on the water quality through the simulations of DBO developed by the QUAL2K embedded in WEAP. The water quality in the Descoberto River was also evaluated under the recently approved water quality regulations in the Federal. The results of the different scenarios suggested stricter regulations for new urban-developments and higher levels of treatment efficiency in the WWTPs.

Recently, rainwater has been used to meet the demand for uses other than human consumption. The artificial wetland—storage tank system built at the Pontificia Universidad Javeriana (PUJ) was built as an alternative source of irrigation for the local area. The system is made up of three components: a catchment system from the drainage pipelines coming from the parking structure, a sub-surface artificial wetland used for the water treatment, and a storage and distribution system for irrigation. A hydraulic and hydrological assessment for the system, a water balance for the system’s tributary areas, and a water demand analysis for the vegetative species at PUJ were carried-out to evaluate the system’s performance. The results from this assessment demonstrated the presence of short-circuiting patterns that affected the wetland hydraulic performance. Furthermore, there were considerable differences between the inflow and the outflow, which suggests a non-optimal water transport inside of the wetland.

This paper summarizes research conducted to revise existing pavement thickness design tables for permeable interlocking concrete pavement (PICP) published by the Interlocking Concrete Pavement Institute (ICPI) in 2011. The study included a literature review, field deflection testing of existing projects and test sections, estimation of the effective stiffness of each layer in PICP structures, mechanistic analysis and structural design of a test track incorporating three different subbase thicknesses (low, medium, and higher risk), tests on the track with a heavy vehicle simulator (HVS) to collect performance data to validate the design approach using accelerated loading, refinement, and calibration of the design procedure using the test track data, development of a spreadsheet based design tool, and development of revised design tables using the design tool. Rut development rate as a function of the shear stress to shear strength ratios at the top of the subbase and the top of the subgrade was used as the basis for the design approach. The revised design tables are based on subgrade soil properties, subbase aggregate properties, the number of 80 kN standard axle loads, and the number of days with standing water in the subbase. The minimum design thicknesses required to prevent subgrade rutting in the revised tables do not differ significantly from those in the 2011 ICPI publication, and are mostly less conservative.

Engineered media is the heart of bioretention system performance. Therefore, preserving media integrity is of the utmost importance. A successful bioretention installation involves oversight not just onsite, but having a framework in place for transferring raw materials to a blended, commercially installed product. This framework should encompass standards of practice utilizing rigorous verification testing for qualifying, sourcing, verifying, producing, storing, and handling media. Media certification must be based on high standards of quality control in bioretention media raw materials and media composition, and use of strict quality assurance methods in the controlled manufacturing process, validated with numerous characterization, composition and performance tests conducted during and after production. Finally, bioretention media should be verified, post-construction, that the media was not compromised during the construction of the bioretention system. In following the appropriate media certification test program, the stormwater designer can be confident that use of media in his/her bioretention plan will yield the same performance as specified in the bioretention design manual.

This study aimed to predict the long term effects of outflow runoff quality from green roofs located at two sites in Adelaide, Australia. Samples of stormwater runoff were collected from Site 1, fertilized, and Site 2, unfertilised intensive and extensive green roofs. The non-parametric Mann Kendall trend analysis was employed in this study. The results for Site 1 showed decreasing trends for EC, turbidity, chloride, and TDS and an increasing trend for pH. There were no trends observed for nitrate and orthophosphate concentrations. The corresponding results for Site 2 showed increasing trends for nitrate+nitrite concentration from beds containing scoria and a sharply increasing trend from beds containing an organic-based media. For the crushed brick media type there was a slight decreasing trend for orthophosphate while total cations did not show any trend. This study demonstrated that the growing media is more likely to be the cause of the observed trends in drainage water.

The major goals of this research were to determine the impact of mean cell residence time (MCRT) on the alpha coefficient (α) and how low dissolved oxygen (DO) concentrations in the aeration basin affect effluent quality. Two, bench-scale activated sludge reactors were operated for 8 weeks. Daily, 18 L of synthetic wastewater were prepared for each reactor by mixing tap water with bacto-peptone, sodium bicarbonate, ammonium sulfate, and other salts. Parameters measured on the influent and effluent included: chemical oxygen demand, total nitrogen, ammonia nitrogen, alkalinity, total phosphorus, and pH. Other effluent parameters monitored included: nitrite, nitrate, oxygen transfer coefficient (K_La), alpha coefficient and beta coefficient (β), and suspended solids. Reactor 1 (R-1) was operated at MCRTs of 20.3±1.5 and 14.1±0.5 days; and Reactor 2 (R-2) at 17.7±2.3 and 12.8±0.8 days, respectively, during the first and second runs. A non-linear regression program was used to determine K_La. Water quality analyses were performed in accordance to HACH procedures. R-1 performed better than R-2 achieving average ammonia removals of 91.2% and 98.1% during the first and second runs; while R-2 achieved ammonia removals of 69.2% and 25.3% respectively during the first and second runs. Alpha coefficients for each run increased as MCRT increased. Oxygen uptake rates were much higher in R-2 than for R-1 and increased as MCRT increased. The nitrogenous oxygen demand of the synthetic wastewater fed to R-2 was approximately 15 g/day compared to 1.6 g/day for R-1 while the same air rate was supplied to each reactor resulting in low DO concentrations and a nitrite buildup in R-2.

This paper presents results from a study to examine the flow and sediment deposition patterns in a new vortex-type stormwater retention pond using physical scale and computational models. The pond, that is circular in plan, has a peripheral inlet and a central outlet, which creates a strong circulation in the pond. Two geometries of the pond were tested. Measurements of the residence time distributions, flow patterns, and sediment deposition patterns were taken at the design flows for the two pond geometries. The effectiveness of an internal berm to improve desirable flow characteristics was also examined. The berm improved flow and sediment deposition in the pond, as the sediment deposition patterns showed that most of the sediments deposited outside the berm. This is considered to be beneficial for pond maintenance. The physical scale model results are also compared to 3D computational fluid dynamics (CFD) modeling results using ANSYS Fluent.

The objective of this research was to assess the feasibility of utilizing the white rot fungus, Pleurotus ostreatus, to decrease the concentration of Escherichia coli found in liquid dairy manure. Corn stalks and spent mushroom compost (SMC) and Phragmites and SMC were used as growth media and support for the fungus within the reactors. We also used the SMC alone as a control treatment. When the concentration of E. coli in the influent manure was reduced, the combination treatments were able to reduce the bacteria concentration consistently throughout the incubation period. We also evaluated the effect of flow rate on the system and found that bacterial reduction was greater at the slower flow rate but the BCR were able to decrease the E. coli concentration at both flow rates. The nutrients contained in the SMC may have influenced the predation behavior of the fungus. The reduction of the C:N was due mainly to changes in total nitrogen in the BCRs. Carbon content increased slightly in all of the treatments except for the SMC-Live control. Further investigation into the relationship between nutrient concentration and fungal growth and predation activity was evaluated. The ligninolytic activity of the WRF is a secondary metabolism typically initiated by low levels of nitrogen and/or carbon. If this is the mechanism utilized by P. ostreatus to kill the E. coli, the nitrogen load of the dairy manure would have to be addressed by the carbon content of the system. This presentation explores the effects of nutrient concentration on the predation behavior of the fungus.

Constructed subsurface flow wetlands have the potential for high phosphorus removal through chemical adsorption onto the media. Over the past decade researchers at Griffith University, Australia have been using 240 L mesocosms to investigate the long term sustainability and performance efficiency of using different soil media and plant species to maximise nutrient removal from secondary wastewater effluent. The performance efficiency of 15 different media mixes including amendments for enhanced phosphorus adsorption, and 10 different plant species have been investigated. Total phosphorus removal was highest (94–99%) in sand media amended with water treatment residuals (WTR), followed by ‘brickies loam’ (92%), then sand amended with red mud or krasnozems (86–89%) and lowest in gravel (44%). Phosphorus removal using sand with WTR had the greatest efficiency when treating influent with P concentrations ranging from 0.5 to 8 mg/L (90–99%). The addition of biochar to sand did not enhance P removal during a two year trial. Leaching and export of P occurred from the media either after heavy rain or loading with stormwater having low P concentrations (<0.06 mg/L). However, following such ‘flushing events’ P sorption and hence P removal efficiency were enhanced. Mature plant assemblages could uptake up to 16gP/m2/year. Of the herbaceous plants the perennial grasses Pennisetum alopecuroides and Vetiver-Chrysopogon zizanioides, and the sedge Carex appressa had the highest biomass. The woody species Callistemon pachyphyllus and Melaleuca quinquenervia had the highest carbon sequestration (1000 g C/m2/year). Thus various sandy loam media can be used to enhance long term effective phosphorus removal, and plants can be used for carbon credits

Wastewater treatment technology has been improved in developing odor control. The odor control strategies aim to minimize odor nuisance beyond the treatment plant facilities’ boundaries. This paper presents the adopted odor control strategy at an advanced WWTP in Egypt that shares boundaries with residents. A comprehensive evaluation of the odors from the plant has been carried out utilizing odor dispersion modeling. The model has simulated the odor dispersion from each treatment process and potential odor source in terms of overall odor units in dilutions to threshold (D/T). The odor can also be measured in hydrogen sulfide (H₂S) equivalents. However, it has been proven that other compounds rather than H₂S can contribute to odors. Depending on tackling solely H₂S might result in inadequate treatment of emissions from treatment processes where H₂S is not the dominant odor source. The main objective of this research is to develop odor dispersion models that could be used to enhance the understanding of how odors generated from wastewater treatment plants and dispersed to the fence line and offsite receptors. The model predicts the concentration, frequency, and spatial extent of odor nuisance released from a proposed treatment plant based on the meteorological and geographical data in addition to the odor emissions estimates for each treatment process. Various mitigation measures are investigated to achieve different odor levels at the plant fence and at the nearest residential area. The results of these analyses show that 5 OU/m³ can be selected as a guideline for current and future designs.

Sediment basins are designed to mitigate damage to delicate natural environmental features such as streams and prevent excessive amounts of water from escaping construction sites as runoff. This runoff is often heavily soil-laden water and often requires an undisturbed settling time in the order of hours or days if fines (e.g., silts) are present. Once settled, however, these fine soil particles may be susceptible to resuspension if during the basin dewatering stage new inflows are admitted. In such conditions, velocity along the bottom of the basin increases significantly and shear forces may lead to resuspension of settled soil particles. Resuspended particles can thus be discharged from the basin, denying the benefits of these structures. In order to minimize the resuspension of soil particles in a sediment basin, an ongoing experimental investigation assess the benefits of containment cells as a lining for the bottom of the basin. By shielding the soil from high velocities and shear forces, significantly less soil becomes disturbed, resuspended, and discharged through weirs and other outlets. Preliminary results indicate significant decrease in turbidity of water samples from the discharge point in the apparatus, associated with an increase in weight of retained soil within the cells. CFD modeling has been used to estimate flow velocity within the cells and determine adequate and low-cost containment cell geometries to mitigate resuspension issues in sediment basins.