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An impervious area of `20` hectares is to be served by a sewer line. This area is subjected to three storms X, Y, Z with equal frequency of occurrence. The duration of three storms is `20` minutes, `30` minutes and `35` minutes respectively. Taking time of concentration equals to `30` minutes. Determine maximum runoff from each storm. [Ans : `0.938` `m^3`/s ,`1.134` `m^3`/s , `1.03` `m^3`/s]
An impervious area of `20` hectares is to be served by a sewer line. This area is subjected to three storms X, Y, Z with equal frequency of occurrence. The duration of three storms is `20` minutes, `30` minutes and `35` minutes respectively. Taking time of concentration equals to `30` minutes. Determine maximum runoff from each storm. [Ans : `0.938` `m^3`/s ,`1.134` `m^3`/s , `1.03` `m^3`/s]
Solution:
For impervious area, `C=1`
For area X,
`t=20 min`
`t_c=30 min`
Since `t
The contribution area is,
`=sum A**t/t_c`
`=20**20/30`
`=13.33 ha`
Now,
`i=760/(30)`
`=25.33` mm/hr
Thus, `Q=(CiA)/360`
`=(1**13.33**25.33)/360`
`=0.939 m^3/s`
For area Y,
`t=30 min`
`t_c=30 min`
In this case, contributing area is equal to entire area i.e, 20 ha.
Thus, `i=1020/(50)=20.4` mm/hr
Thus, `Q=(1**20.4**20)/360=1.134 m^3/s`
Again for area Z,
`t=35 min`
`t_c=30 min`
since `t>t_c`, contributing area is equal to entire area i.e, 20 ha.
Thus,
`i=1020/(35+20)`
`=18.55` mm/hr
Now,
`Q=(1**18.55*20)/360`
`=1.03\ m^3/s`
All Chapters
Introduction
Quantity of Waste Water
Design of sewers Tutorial
Treatment of WasteWater
Similar Question
Determine the quantity of sewage in `m^3`/sec for the combined system from the following data :
- `50 %` of the area is roofs and pavements (`C_1 = 0.8`)
- `50 %` of the area is vacant plots (`C_2 =0.1`)
- Area of the community ` 5` hectares
- Population density = `700` persons/hectare
- Water supply rate = `150` lpcd.
- Peak factor = `3`
- Time of concentration =`10` minutes.
An impervious area of `20` hectares is to be served by a sewer line. This area is subjected to three storms X, Y, Z with equal frequency of occurrence. The duration of three storms is `20` minutes, `30` minutes and `35` minutes respectively. Taking time of concentration equals to `30` minutes. Determine maximum runoff from each storm. [Ans : `0.938` `m^3`/s ,`1.134` `m^3`/s , `1.03` `m^3`/s]
Assuming the surface on which rainfalls in thickly built residential district as follows: `40 %` area consist of roofs and pavements having impermeability factor `C` as `0.85`, `40 %` of area consists of lawns and gardens having `C` as `0.20` and remaining area consists of ground surface having `C` as `0.1` .If the total area draining to the sewer is `5` hectares and maximum intensity of rainfall is `50` mm/hr, estimate the probable runoff from the area.
