Application of the log-normal and normal distributions to stormwater quality parameters

Buren, M. A. Van; Watt, W. E.; Maršálek, Jiří

doi:10.1016/s0043-1354(96)00246-1

Cited by 96 publications

(38 citation statements)

References 9 publications

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“…A study that was conducted in the same local area as this study also found that the concentrations of stormwater constituents in this region have a log-normal distribution (Bellevue 1995). A more recent study found that many stormwater constituent concentrations have a log-normal distribution upon entering a pond, but change at the pond outlet to a normal distribution (Van Buren et al 1997).…”

Section: Discussionmentioning

confidence: 99%

Storm Water Pollutant Removal by Two Wet Ponds in Bellevue, Washington

2000

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Two wet detention ponds were investigated for their ability to remove pollutants, primarily phosphorus, from stormwater runoff. The two ponds lie within the Phantom Lake watershed, a sub-basin of the Lake Sammamish watershed in Bellevue, Washington, which is developed as a commercial and residential area with impervious surface area as high as 57%. There are design differences between the two ponds, yet both are comparable to design recommendations set forth by local agencies. One pond was built for flow attenuation and water quality treatment; the other serves only to improve water quality. Fifteen storms and two baseflows were successfully sampled during the Northwest's wet season from October 1996 through March 1997. Pollutant removals varied between a fifth to a half for phosphorus, and greater than half for total suspended solids and most of the analyzed metals. Removal efficiencies were consistently better in the pond designed primarily for water quality.

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Section: Discussionmentioning

confidence: 99%

Storm Water Pollutant Removal by Two Wet Ponds in Bellevue, Washington

2000

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“…Such procedures have been tested by various workers against annual load estimates derived from deterministic multi-parameter hydrologic methods and have been found to either match or even outperform the more complex modelling algorithms (Van Buren et al, 1997). The functionality of complex operational modelling can be confounded by definitions of boundary conditions as well as process dynamics and kinetics which often make them difficult to calibrate and unwieldy to implement and collect reliable real-time data.…”

Section: Methodology and Study Sitesmentioning

confidence: 99%

Urban surface water pollution problems arising from misconnections

Revitt

Ellis

2016

Science of The Total Environment

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The impacts of misconnections on the organic and nutrient loadings to surface waters are assessed using specific household appliance data for two urban sub-catchments located in the London metropolitan region and the city of Swansea. Potential loadings of biochemical oxygen demand (BOD), soluble reactive phosphorus (PO 4 -P) and ammoniacal nitrogen (NH 4 -N) due to misconnections are calculated for three different scenarios based on the measured daily flows from specific appliances and either measured daily pollutant concentrations or average pollutant concentrations for relevant greywater and black water sources obtained from an extensive review of the literature. Downstream receiving water concentrations, together with the associated uncertainties, are predicted from derived misconnection discharge concentrations and compared to existing freshwater standards for comparable river types. Consideration of dilution ratios indicates that these would need to be of the order of 50-100:1 to maintain high water quality with respect to BOD and NH 4 -N following typical misconnection discharges but only poor quality for PO 4 -P is likely to be achievable. The main pollutant loading contributions to misconnections arise from toilets (NH 4 -N and BOD), kitchen sinks (BOD and PO 4 -P) washing machines (PO 4 -P and BOD) and, to a lesser extent, dishwashers (PO 4 -P). By completely eliminating toilet misconnections and ensuring misconnections from all other appliances do not exceed 2%, the potential pollution problems due to BOD and NH 4 -N discharges would be alleviated but this would not be the case for PO 4 -P. In the event of a treatment option being preferred to solve the misconnection problem, it is shown that for an area the size of metropolitan Greater London, a sewage treatment plant with a Population Equivalent value approaching 900000 would be required to efficiently remove BOD and NH 4 -N to safely dischargeable levels but such a plant is unlikely to have the capacity to deal satisfactorily with incoming PO 4 -P loads from misconnections.

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“…However, it is commonly known that stormwater constituents are lognormally distributed (Athayde et al, 1983;Duncan, 1999;Van Buren et al, 1997). As a result, the arithmetic mean is likely to overestimate SMC and produce a lower confidence interval bound that is less than zero.…”

Section: Methodsmentioning

confidence: 99%

Prediction of long-term urban stormwater loads at single sites

May¹,

Sivakumar²

2013

Proceedings of the Institution of Civil Engineers - Water Manag

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Long-term total phosphorus loads from 17 urban catchments in the USA were predicted using five different measures of central tendency defining site mean concentration (arithmetic mean, geometric mean, median, harmonic mean and flow-weighted mean). Overall, the flow-weighted mean concentration produced the most accurate predictions of long-term loads. The geometric mean produced the second most accurate predictions. Along with the median and harmonic mean, the geometric mean predicted long-term load relatively well at most catchments exhibiting negative correlations between event mean concentration and total event runoff depth. However, they significantly underestimated long-term load at catchments exhibiting a positive correlation between these variables. Better estimates of long-term load at these two catchments were produced using the flow-weighted mean and arithmetic mean. However, the arithmetic mean tended to overestimate long-term load at the remainder of catchments.

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Application of the log-normal and normal distributions to stormwater quality parameters

Cited by 96 publications

References 9 publications

Storm Water Pollutant Removal by Two Wet Ponds in Bellevue, Washington

Storm Water Pollutant Removal by Two Wet Ponds in Bellevue, Washington

Urban surface water pollution problems arising from misconnections

Prediction of long-term urban stormwater loads at single sites

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