Transcript of Characterisation of surface water runoff from an urban residential sewer separation scheme Dave...
- Slide 1
- Characterisation of surface water runoff from an urban
residential sewer separation scheme Dave Morgan, Paul Johnston and
Laurence Gill Trinity College Dublin Phil Collins HRD Technologies
Ltd Kwabena Osei Hydro International morgandt@tcd.ie Department of
Civil, Structural & Environmental Engineering Trinity College
Dublin
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- MotivationCatchment Introduction Considerable research
conducted on source-area or end of pipe solids characterisation and
modelling..... but SS prediction still a challenging proposition
Can the consideration of a system mass balance: -Improve prediction
of suspended solids and associated pollutants in the runoff -Inform
SuDS retrofit MbMb M sew MgMg M hs M out M wo M wo = M g + M sew +
M hs + M out Methodology -Field monitoring of small urban
residential catchment (18 months) -Characterisation of sediment
(loadings / PSD / TP / Cu / Pb / Zn) -Modelling of the suspended
solids RG HDVS Separate Pipe and Gully System
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- Project OutlineCatchment Introduction River Poddle 225 450 225
Stormwater sampling
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- ComparisonRunoffGully Sediment yield Build-up rates 0.5 10.5
g/m 2 /day (bitmac road) ~ 0.05 g/m 2 /day (concrete footpath)
Particle size D 50 = 1200m 10% < 200m Washoff
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- ComparisonRunoffWashoff Sediment yield 1 3 5 7 9 6 8 10 4 2
Gully sediment characteristics Annual accumulation of 36kg (10
gullies, 30% of imp. area) D 50 =1000m 13% < 200m Gully
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- ComparisonRunoffWashoffGully Sediment yield SSC -19 events/231
discrete samples - 30% of annual runoff volume -Site median EMC =
29mg/l -Total mass: 40kg PSD -D 50 = 34 microns -90% < 200m
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- ComparisonRunoffWashoffGully Sediment yield
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- Conclusions Gullies ineffective in trapping < 200 m
particles 2 4 times higher annual pollutant load in SS compared to
gully sediments High uncertainty in source loading rates modelling
of SS washoff required to determine mass balance Thanks for
listening.... Current work Modelling of suspended solids at the
outlet Partitioning of easily eroded and stable solids
fractions