6. Detention ponds In the figures below is a line draft of the detention ponds. On figure 4 the entire square is lowered. In the dent there is three wet ponds with gravel and plants.
Figure 5 shows three connected basins with high edges of 1m internal depth, 0,5m external. The basins can contain 284m3.
The volume of those three are 312 m3. The capacity of the entire square is 1714m3.
In total the capacity runs up to approximately 2000m3.
+ 5.00 + 4.50
+ 5.00
+ 4.00 + 3.50
+ 4.50
+ 4.00
+ 3.50
+ 2.50
+ 5.00 Figure 4
Figure 5
The volume is found by,
With a return period of 10 years,
Vol=(i*Fr-Qout)*tr
c= 45960 tr = 20min - 4 days, rain duration [s] α= 0,79 Fr = 6,1669, catchment area [ha] Qout = 16, outflow [l/s]
i=c*tr-α
i is the rain intensity [l/s*ha]
Vol=((c*tr-α)*Fr-Qout)*tr
[Bentzen]