A Synopsis of Technical Issues for Monitoring Sediment in Highway and Urban Runoff

Bent, Gardner C.; Gray, John R.; Smith, Kirk P.; Glysson, G. Douglas

doi:10.3133/ofr2000497

Cited by 32 publications

(23 citation statements)

References 47 publications

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“…The adopted system includes the following classes: Very Fine (<8 µm), Fine (8-63 µm) and Medium (63-500 µm). Approximately an 8-fold increase in particle size defines the boundary of each class and the class ranges are consistent with the particle size classification modified from Guy (1969) and recommended by Bent et al (2000) for sediment analysis. Very Fine Particles (VFP) includes 'very fine silts' and 'clays', Fine Particles (FP) covers 'fine silts' to 'coarse silts' and Medium Particles (MP) covers 'very fine sands' to 'medium sands' under the Bent et al (2000) system.…”

Section: Determination Of Suspended Particles In Storm Runoffsupporting

confidence: 75%

“…This simple design allows the sampled flow to be isokinetic and vertically integrated with the runoff flow. Transport of particles larger than 40 μm is not uniform with flow depth (Bent, et al 2000), and the vertical partitioning by the flow splitter provides representative sampling across a range of particle sizes. Hydraulic testing demonstrated that the sampling device is capable of obtaining a constant proportional sample flow (within ± 2%) for discharges up to 5 L/s.…”

Section: Runoff Samplingmentioning

confidence: 99%

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Suspended particle characteristics in storm runoff from urban impervious surfaces in Toowoomba, Australia

Brodie

Dunn

2009

Urban Water Journal

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Total Suspended Solids as a measure of suspended particles in urban stormwater has limitations and the alternative Suspended Sediment Concentration method was adapted to determine Non-Coarse Particle (NCP) concentration, defined as particles smaller than 500 μm. NCP was partitioned into the following classes: Very Fine Particles (<8 µm, VFP), Fine Particles (8-63 µm, FP) and Medium Particles (63-500 µm, MP). A Site Mean Concentration approach was adopted to differentiate the suspended particle characteristics between three impervious surfaces (roof, road and carpark) using runoff data collected for 35 storms.Runoff particle size distribution (PSD) of all surfaces was dominated by particles less than 63 μm. A weak trend of relatively constant VFP concentration was present in the road runoff data. Roof runoff PSD became finer as NCP concentration increased and, overall, the PSD of carpark runoff was coarser compared to road and roof runoff. These findings have runoff treatment implications as settling processes are influenced by particle size. IntroductionPollution due to urban stormwater is a significant environmental issue. A management philosophy to reduce, detain, infiltrate, treat or use stormwater at its source has emerged to reduce the adverse impacts of urban stormwater. This approach is variously termed 'low impact development' (LID), 'water sensitive urban design' or 'sustainable urban drainage systems'. A common LID feature is the strategic use of small-scale and on-site controls on urban stormwater, including non-structural measures such as alternative road layouts to minimize imperviousness. Several LID-type design guidelines are available (e.g. CIRIA, 2000 used in Scotland). The introduction of LID has highlighted a need for more information about the characteristics of stormwater generated from specific urban surfaces such as roads and roofs.3 Suspended particle load in urban runoff is a key pollutant leading to reduced water clarity in receiving waters. Due to the affinity of heavy metals and other contaminants to particles, stormwater treatment systems generally involve some form of particle separation process. On this basis, Total Suspended Solids (TSS) is a common performance indicator used in urban stormwater planning and analysis. Determination of TSS concentration is accepted practice to characterise suspended particles in runoff, but research has disputed the validity of using TSS as a reliable measure in stormwater (Knott, et al. 1992;Gray, et al. 2000). An alternative measure, referred to as Non-Coarse Particle (NCP) concentration is described in this paper.This paper is based on stormwater monitoring data collected from three impervious surfaces; a road, a carpark and a roof, located in Toowoomba, Australia (Brodie, 2007). The NCP test methods, the monitored impervious surfaces and a passive stormwater sampling device developed as part of the study are described.Suspended particle characteristics in runoff from each surface are also described based on statistical analysis of the m...

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Section: Determination Of Suspended Particles In Storm Runoffsupporting

confidence: 75%

Section: Runoff Samplingmentioning

confidence: 99%

Suspended particle characteristics in storm runoff from urban impervious surfaces in Toowoomba, Australia

Brodie

Dunn

2009

Urban Water Journal

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“…Automatic samplers have been documented to capture particles in this size range, but no measure of consistency of capture has been provided. Similar to Bent et al (2001), Burton and Pitt (2002) stated that automatic samplers are not efficient at sampling the largest particles, which are found in the bedload flows. They noted that particles having settling velocities in the 1-to 15-cm/sec range (100-to 1000-lm size) are found in grit chambers and catchbasins at inlets to drainage systems, but seldom are obtained in Figure 1-Reported PSD of stormwater runoff and street dirt samples (residential/commercial: House et al, 1993;OH highway: Cristina et al, 2002;street dirt: Pitt, 1979; CA highway 1 and 2: Li et al, 2005;LA highway: Kim and Sansalone, 2008; source area inlet: Morquecho, 2005;NJDEP: NJDEP, 2003;Portland BES: City of Portland, 2004).…”

Section: Introductionmentioning

confidence: 88%

“…Maintaining a homogeneous distribution of the particles in the water is difficult, even with adequate stirring (as discussed later), especially when large particles are present. However, at higher flows and higher solids concentrations, the differences between fixed-point autosamplers and cross-section, depth-integrated samplers is small (Bent et al, 2001;Breault and Granato, 2000;Horowitz et al, 1990;Krug and Goddard, 1986), such as the ,20% difference noted in sediment concentrations between paired samples collected with a fixed-point autosampler and a cross-section, depth-integrated sampler (Bossong et al, 2006). However, the differences remain high (40%) at low solids concentrations (Graczyk et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Only recently has attention been focused on quantifying the errors associated with each phase of this process, with most of the activity focusing on quantifying the concerns regarding analysis technique, including storage time and temperature and effect of PSD (Chan et al, 2008;Clark and Pitt, 2008;Siu, 2008a, 2008b;Guo, 2005Guo, , 2007Li et al, 2005;Siu et al, 2008). Earlier work by the U.S. Geological Survey (Reston, Virginia) (USGS) (Bent et al, 2001;Edwards and Glysson, 1999;Winterstein and Stefan, 1983) quantified some of the concerns regarding the ability of automatic samplers to capture solids in the different size ranges and densities that can be associated with stormwater runoff. Guidance, as summarized below, has been developed to adapt wastewater automatic samplers to stormwater monitoring, with the research results reported within these guidance documents.…”

Section: Introductionmentioning

confidence: 99%

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Peristaltic Pump Autosamplers for Solids Measurement in Stormwater Runoff

Clark

Siu

Pitt

et al. 2009

Water Environment Research

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Regulatory agencies approve automatic samplers containing peristaltic pumps as a sample collection method for stormwater characterization and for treatment-device evaluation. Autosampler performance, as discussed in the limited available literature, can vary across the entire particle size range typically found in stormwater from different source areas and outfalls-reasonably consistent performance for particle sizes ,250 lm, but much less consistency for particles .250 lm. Therefore, a series of experiments was undertaken to quantify the upper range of consistent particle capture that may occur with sampling stormwater suspended sediment and particulate-bound pollutants. These experiments, based on triplicate sampling at each experimental condition, found that peristaltic pump autosamplers commonly used in stormwater monitoring could not repeatedly and effectively capture particles .250 lm from a simulated stormwater whose particles have a specific gravity of 2.65. It was expected that the effective size for autosamplers would be correspondingly larger for particles having smaller specific gravities. The height of the sampler had no influence on particle recovery up to a height of 2.5 m, with slightly decreasing recoveries of large particles occurring at greater heights, as a result of reduced sampler intake velocity. Therefore, to characterize the solids across the entire size range and specific gravities that may occur in stormwater runoff, autosamplers should be deployed in conjunction with bedload and floatables sampling. Water Environ. Res., 80 (2008).

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