Chi-Yuan Fan’s research while affiliated with United States Environmental Protection Agency and other places

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Publications (24)


Fig. 1. Side view of experimental flume setup 
Fig. 2. Grain size distribution of sediment used in laboratory testing 
Fig. 3. Weight of sediment flushed versus gate opening height. Initial water depth in flushing tank was 86.4 cm. Initial thickness of sediment in flume was 2.5 cm; Initial water depths in flume vary.
Fig. 4. Weight of sediment flushed versus gate opening height. Initial water depth in flushing tank was 44.5 cm. Initial thickness of sediment in flume was 2.5 cm; Initial water depths in flume vary.
Fig. 5. Measured and fitted time variations of water depth in flushing tank for test run No. 68
Gate and Vacuum Flushing of Sewer Sediment: Laboratory Testing
  • Article
  • Full-text available

May 2004

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757 Reads

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41 Citations

Journal of Hydraulic Engineering

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Chi-Yuan Fan

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Ramjee Raghaven

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The objective of this study was to test the performance of a traditional gate-flushing device and a newly designed vacuum-flushing device in removing sediment from combined sewers and CSO storage tanks. A laboratory hydraulic flume was used to simulate a reach of sewer or storage tank. The flushing device was fabricated and installed at upstream end of the flume. The removed sediment was collected at downstream end of the flume and weighed. The test results indicate that the weight of flushed sediment increases with increasing initial water depth in the flushing device; the weight of flushed sediment decreases with increasing initial water depth in the flume: the weight of flushed sediment only changes slightly with changing height of flushing device opening for water release and does not necessarily increase with increasing opening height. Water is held up by vacuum and is released upon dissipation of the vacuum in the vacuum-flushing device rather than through closing and opening of a mechanical gate in the gate-flushing device. The test results indicate that sediment removal efficiency of the vacuum-flushing device is practically the same as the gate-flushing device.

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Sewer-Sediment Control: Overview of an Environmental Protection Agency Wet-Weather Flow Research Program

April 2003

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34 Reads

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41 Citations

Journal of Hydraulic Engineering

This paper presents a historical overview of the sewer sediment control projects conducted by the Wet-Weather Flow Research Program of the United States Environmental Protection Agency. The research presented includes studies of the causes of sewer solids deposition and development/evaluation of control methods that can prevent sewer-sediment accumulation. Discussions focus on the relationship of wastewater characteristics to flow-carrying velocity, abatement of solids deposition and solids resuspension in sewers, and sewerline flushing systems for removal of sewer sediment. Methods for abating sewer sedimentation include steeper sewer slope, pipe bottom shapes that maintain high velocity during low-flow conditions, and periodic sewer flushing. The future research program plan for sewer-sediment control is also presented.


Costs of Best Management Practices and Associated Land for Urban Stormwater Control

January 2003

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84 Reads

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77 Citations

Journal of Water Resources Planning and Management

James P. Heaney

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Chi-Yuan Fan

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[...]

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New methods are used to evaluate stormwater controls and Best Management Practices (BMPs) within a land development context. Costs are developed using published literature and standard cost estimation guides. A method is developed in which costs are determined for each parcel within a development for specific land uses. The effect of including the opportunity cost of land in the analysis is evaluated. Costs attributable to stormwater controls are allocated among purposes. A method is developed in which stormwater control costs are assigned at the parcel level. Data gaps and research needs are then explored in the context of addressing this complex problem.


ESTIMATING URBAN WET-WEATHER POLLUTANT LOADING

January 2003

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10 Reads

Proceedings of the Water Environment Federation

This paper presents procedures for estimating pollutant loads associated with the major sources of solids and solid materials in urban wet-weather flow. Equations are presented for the annual quantity of litter and floatables; the quantity of sand used on highways for traction during snowstorms; loadings of dust-and-dirt accumulated on street surfaces during dry weather; soil erosion within urban areas; and the load associated with the resuspension of sediments and solids deposited in urban sewers. Although dissolved contaminants are not addressed, these equations may be used to estimate the total maximum daily loads for watershed management plans.During low-flow, dry-weather periods, sanitary wastewater solids deposited in combined sewers have significant adverse impacts on the integrity of sewerage system. In the U.S., estimates of dry weather flow deposition in combined sewers vary from 5 to 30% of the daily inputs of solids and pollutants. In Europe, average deposition rates have been measured at between 30 and 500 g/m/d. Even sewers that are supposedly designed to be `self-cleansing' will have transient sediment deposits and part of the load in transport will move toward the sewer invert.Deposited organic matter contains high concentrations of sulfates that can be reduced to hydrogen sulfide under anoxic conditions often reached in a sewer. The hydrogen sulfide is then oxidized to sulfuric acid, a highly toxic and corrosive gas, by biochemical transformation. The concentration of BOD5, COD, and NH3-N in sewer sediments can be as high as 150,000 mg/L, 200,000 mg/L, and 300 mg/L, respectively. During a storm event, resuspended sediments are discharged directly into receiving waters. Thus, sewer sedimentation should be controlled.


Development of a decision-support framework for placement of BMPs in urban watersheds

January 2003

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24 Reads

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5 Citations

Proceedings of the Water Environment Federation

The U.S. Environmental Protection Agency (EPA) has initiated a research project to develop an evaluation framework for the optimal placement of best management practices (BMPs) options at strategic locations in mixed land use urban watersheds. The integrated watershed-based stormwater management decision-support framework (ISMDSF) is to be based on a geographical information system (GIS) watershed/BMP database, cost, and hydrologic, hydraulic, and water quality modeling to achieve desired water quality objectives. The initial phase of this research is expected to be completed in early 2005. While this work is ongoing and many tasks have yet to start, this paper presents the project background, rationale, approach, initial review findings of watershed and BMPs models, and the preliminary design recommendations of the framework.


Sewer-sediment control: Overview of an EPA wet-weather flow (WWF) Research Program

January 2003

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37 Reads

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29 Citations

This paper presents a historical overview of the sewer sediment control projects conducted by the Wet-Weather Flow Research Program of the U. S. Environmental Protection Agency. Research presented includes studies of the causes of sewer solids deposition and development/evaluation of control methods that can prevent sewer-sediment accumulation. Discussions focus on the relationship of wastewater characteristics to flow-carrying velocity, abatement of solids deposition and solids resuspension in sewers, and sewerline flushing systems for removal of sewer sediment. Methods for abating sewer sedimentation include steeper sewer slopeage, pipe bottom shapes that maintain high velocity during low-flow conditions, and periodic sewer flushing. The future research program plan for sewer-sediment control is also presented.


THE COMPLICATIONS OF MONITORING TREATMENT BMPs

January 2003

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9 Reads

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1 Citation

Proceedings of the Water Environment Federation

The use of best management practices (BMPs) in an urban watershed can provide pollutant load reductions at a relatively low cost. BMPs can range from being management operations (such as street sweeping or reducing the amount of pesticides used on urban lawns) to structural treatment options (the four most common alternatives being detention/retention ponds, swales, filter/buffer strips and constructed wetlands). Evaluation of BMP performance requires adequate monitoring to report ?true? values of their treatment capabilities. This paper focuses on the complications associated with monitoring structural BMPs and provides an overview of the drawbacks of existing monitoring systems, limitations of monitoring devices and methodologies, inadequacies of commonly used monitoring parameters and their impacts on the performance and design of treatment BMPs. One of the complications of existing monitoring systems is that we measure standard parameters instead of those pertinent to pollutant removals. For example, total suspended solids is frequently measured to indicated the solids loading and removal in a retention pond. But a more important measurement could be total settleable solids, since only those particles that will settle out in the retention pond are pertinent to its effectiveness. Further, determination of particle size and settling velocity distribution of the solids is important because a significant portion of pollutants present in stormwater are adsorbed on the finer fraction of the suspended solids. A significant portion will not settle out in a retention pond, so no matter how large the pond is designed, reasonable pollutant removals cannot be expected. However, particle size distribution estimates are not only time consuming but also expensive, so they are rarely done in routine monitoring of BMPs. Proper monitoring is absolutely necessary if we are to best evaluate the effectiveness of BMPs and their impact in improving water quality in urban watersheds.



Flushing for Sewer Corrosion and Pollution Control

February 2002

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7 Reads

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1 Citation

This paper overviews causes of combined-sewer deterioration and their heavy pollutant discharges caused by rain events together with a discussion of their control methods. In particular, it covers in-sewer and combined-sewer overflow (CSO) storage-tank-flushing systems for removing sediments and minimizing hydrogen sulfide production, resulting in the reduction of associated pollution and sewerline corrosion, respectively. Performance of two technologies, i.e., the tipping flusher, (TF) and the flushing gate (FG) were evaluated by a detailed examination of 18 facilities in Germany, Canada, and the United States. Results indicate that both the TF and FG technology appear to be a cost-effective means for flushing solids and debris from CSO storage tanks, while the FG is considered to be the most efficient method for controlling combined-sewer sediment.


Citations (18)


... In the United States of America (USA), total gross water consumption exceeds the total available freshwater supply in many southern states, including California, Florida, Texas and Arizona (Fan and Field 2002). To address the decline of per capita freshwater availability, the USA has introduced a variety of innovative water management practices, including roof rainwater harvesting, wastewater reclamation and aquifer recharge measures. ...

Reference:

Review of Stormwater Harvesting Practices
Beneficial Use of Urban Stormwater
  • Citing Chapter
  • August 2002

... The complex composition of sewage pollutants results in the intricate composition of deposits. Ahyerre et al. [20] classified sewage deposits into three categories based on their physicochemical properties: gross bed sediment (GBS), organic layer (OL), and biofilm. Among these, GBS consists mainly of inorganic solids such as sediment and macromolecular organic matter (COD or BOD 5 ), which deposit in sewers in large quantities during the dry season. ...

Innovative wet-weather flow collection/control/treatment systems for newly urbanizing areas in the 21st century
  • Citing Article
  • January 1999

... We focused on the first-order removal rate because it is the more fundamental parameter; i.e., the overall removal rate achieved by a biofilter will depend on both the rate at which FIB are removed by one or more mechanisms (k obs ) and the advective and dispersive transport processes that determine the biofilter's residence time distribution. 47 Thus, plants can affect overall FIB removal in at least three potential ways: (1) creating new mechanisms by which FIB are removed in the biofilter, for example, by growing roots that serve as collectors for FIB, 40 creating habitat for micro-and meso-faunal grazers that remove FIB through predation, 19,37,38,62 and altering the survival rates of FIB through, for example, competition for nutrients; 34 (2) altering the single collector contact efficiency and attachment efficiency through promotion of biofilm growth, 63 generation of surface-active plant exudates, 64 and creation of preferential flow paths that limit stormwater/biofilter media interactions; 65,66 and (3) changing the infiltration rate which, in turn, alters the biofilter's residence time distribution, 66 the single-collector contact efficiency (see Figure 1), and ultimately the first-order filtration rate (see eq 5). ...

Urban wet-weather flows
  • Citing Article
  • June 1997

Water Environment Research

... The presence of sediment deposits in storm sewers can cause pipe blockage, a reduction in hydraulic capacity, resulting in low drainage efficiency (Todeschini et al. 2010;Regueiro-Picallo et al. 2018;Yang et al. 2019;Liu et al. 2021). Moreover, the pollutants attached to the sediment particles can be re-released and thus form hydrogen sulfide and methane by actions of chemical and/or biological processes, inducing water quality of receiving water bodies, odor concerns, and pipe corrosion (Fan et al. 2003;Liu et al. 2015Liu et al. , 2021Chen et al. 2022). ...

Sewer-Sediment Control: Overview of an Environmental Protection Agency Wet-Weather Flow Research Program
  • Citing Article
  • April 2003

Journal of Hydraulic Engineering

... Concentrations of total N and P often increased during the initial period of storm runoff, likely because of washoff of particulate plant material. Fan, et al. (2001b) reviewed the transport of toxic pollutants through multiple media and drainage systems in urban watershed during wet-weather periods and found that a major portion of priority pollutants (including benzene, polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, and heavy metals) are in particulate form, or sorbed onto particles. Table 3 summarizes inlet and outlet concentrations for total and dissolved metals (Cd, Cr, Cu, Pb, Ni, and Zn), TSS, hardness and total oil and grease for a retrofitted pond in Sunnyvale, CA. ...

Toxic Pollutants in Urban Wet-Weather Flows: An Overview of the Multi-Media Transport, Impacts, and Control Measures
  • Citing Conference Paper
  • May 2001

... Multiobjective optimization for water resource problems that encompass long-and short-term strategies includes work by Ostfeld and Tubaltzev (2008) on water distribution systems, Cembrano et al. (2004) on flooding and sewer overflow volumes, and Dhar and Datta (2008) and Celeste et al. (2004) on reservoir operations. Although many papers have suggested offline improvements to sewer systems (Moeini and Afshar 2012;Lai et al. 2000;Muleta and Boulos 2007;Campisano et al. 2016), to the authors' knowledge, existing work has not combined possible infrastructure changes and optimal online operation. This work extends these applications to evaluate the impacts of sewer pipe size on minimizing CSOs that are optimized for real-time control. ...

Collection System Modeling for Planning/Design of Sanitary Sewer Overflow (SSO) Control
  • Citing Conference Paper
  • September 2000

... The cost of the implemented solution can be calculated using a mathematical formula as it is proportional to the cost of NBS per surface unit. A strategy used to calculate that unit cost has been proposed in (Fan et al. 2000). Furthermore, in some case studies, a cost module is integrated into the framework (Lee et al. 2012). ...

Costs of Urban Stormwater Control
  • Citing Conference Paper
  • September 2000

... These waste waters need to be collected, treated and stored in silos or pools often made of concrete before or during the treatments . Due to chemical and microbiological reactions the pH of the stored materials could be acidic [1][2][3]. It is well-known, that acidic circumstances effect harmful the cement-based matrix. ...

Sewer and Tank Flushing for Sediment, Corrosion, and Pollution Control

Journal of Water Resources Planning and Management

... But current tools and theories used to design and expand sanitary sewer networks, particularly in LMICs, do not sufficiently account for urbanization and climate change. Infrastructure implemented today must be capable of accommodating or mitigating the future threats of climate change and urbanization over its long lifetime (75-100 years; Burian et al. 1999) to provide robust sanitation (World Bank 2020). Failing to adequately consider uncertainties throughout the long lifetime of infrastructure systems can result in too little or too much capacity, with dangerous or costly consequences (Boland and Loucks 2021). ...

Historical Development of Wet-Weather Flow Management

Journal of Water Resources Planning and Management

... The factors can be mainly classified into flushing hydraulics, pipe geometry, and sediment properties (Montes et al. 2021). These three factors include parameters, such as stored water head (Guo et al. 2004), number of flushes (Bong et al. 2013), flushing duration (Campisano et al. 2004), flow velocity (Sun et al. 2022), bed shear stress (Yang et al. 2019), backwater (Jin et al. 2016), pipe slope (Zhang et al. 2011), pipe diameter (Safari et al. 2018), pipe cross-section shape (Safari & Aksoy 2021), surface roughness (Knight & Sterling 2000), sediment cohesiveness (Regueiro-Picallo et al. 2018;Tang et al. 2020), sediment thickness and width (Campisano et al. 2019;Montes et al. 2021), sediment particles median grain size (Zhang et al. 2011), gradings, porosity, anddensity (Campisano et al. 2019;Sun et al. 2022). By studying these factors, researchers aimed to address flushing efficiencies in sewer cleaning and to propose simple dimensionless equations for the design and operations of self-cleaning devices. ...

Gate and Vacuum Flushing of Sewer Sediment: Laboratory Testing

Journal of Hydraulic Engineering