Representative Particle Size of Sediment in Storm Sewer Inlets

Abstract

Problem statement: The aim of this study was examine the representative particle size of noncohesive sediment samples collected from different storm sewer inlets in residential catchments within Kuwait. Approach: A number of 25 sediment samples were collected from storm sewer inlets located in five residential areas in Kuwait: Bayan, Al-Nuzha, Al-Feiha, Al-Andalos and Al-Rumaithya. All the impervious areas for the selected sites are hydraulically connected to the drainage system, including the roofs for houses which are piped to the roads with gutters and thus have pronounced influence on catchment hydrology. Results: It was found that the sample median and mean particle sizes vary locally within each site and spatially compared to others, while the mode is invariant for most of the cases. This result suggests that the mode particle size is more stable in terms of magnitude than the median and mean and may constitute a robust estimator for sediment sizes reflecting the similarity found in watershed characteristics. Conclusion/Recommendations: This is the first such study conducted in Kuwait on sediment samples collected from five residential storm sewer inlets were employed to examine the average particle size readily available for transportation into the conduit.

Statistical Analysis and Determination of Representative Size for Sediment in Malaysian Urban Drains

“…The 10 locations are Bandar Kangar, Butterworth, Ipoh, Shah Alam, Seremban, Kuantan, Kuala Terengganu, Kota Bahru, Kuching (residential) and Kuching (commercial). This has some similarity to the sediment samples from 5 residential areas in Kuwait where the samples skewed to the right [9]. This showed that most of the samples were not of normal distribution, thus using the median diameter, 50 d might not be a good representative of the sediment samples size.…”

“…Mean, being the average of the particle size varies depending on the nature of the sediment data; while median may become sensitive to the shape of the data set distribution and often does not depict the typical outcome. Mode, on the other hand is less bias due to the nature of mode that always represent the highest percentage of particle by weight [9].…”

“…An analysis of the data from 125 gravel-bed streams mostly from the United States with unimodal distribution have suggested in using ISSN: 2289-7771 287 the mode value of 68.8% or close to 70 d to be a suitable representation of the sediment distribution [8]. As for urban drain, a study on the sediment distribution collected from 5 residential areas in Kuwait has shown that the distribution tends to skew to the coarser particle (for unimodal distribution) with a mode size of 0.3 mm and mode percentage value ranging from 11% to 33% [9]. The suggestion that mode as being useful in studying sediment mixture is based on the basis that mode is a less bias statistical parameter since it always represents the highest percentage of particles by weight and covers the largest portion when compared to any other size class.…”

Rectangular Storm Sewer Design Under Equal Sediment Mobility

“…The main advantage of designing a sewer with a rectangular cross section is the flexibility of selecting a channel depth and changing the width to acquire larger flows, while in circular sections the sewer size is proportional to the pipe diameter. A common problem in sewer design is to avoid sediment deposition at the bottom of the conduit (Kleijwegt, 1992;Almedeij et al, 2010). This problem has adverse impact on the environment as the sediment can act as pollution store or generator that can be washed out by the first flush into receiving water (Artina et al, 2007;Almedeij et al, 2010;Mannina and Viviani, 2010).…”

“…A common problem in sewer design is to avoid sediment deposition at the bottom of the conduit (Kleijwegt, 1992;Almedeij et al, 2010). This problem has adverse impact on the environment as the sediment can act as pollution store or generator that can be washed out by the first flush into receiving water (Artina et al, 2007;Almedeij et al, 2010;Mannina and Viviani, 2010). The deposits under severe conditions may also cause early water surcharge resulting with a reduction in conduit hydraulic capacity (Ackers, 1991).…”