wastewater disposal and water supply preliminary report woodlane

2.1.2 Capacity Assessment
To determine the current system load and its capacity for future expansion, a
stand-alone assessment of the Woodlane sewerage was computed and is
attached in Appendix E. Some assumed parameters of the assessment are as
follows:
Peak factor 3
Average daily flow 490 L/connection/day
The calculated flows for the pump stations are summarised below in Table 3.
Table 3 – Pump Stations Summary
Pump
* Storage
ADF Peak Flow Pump
Time to Overflow Time to Overflow
Station
Capacity
(L/d) (L/s) duty (L/s)
(Local catchment) (System)
No.
(m 3 )
1 28,910 1.004 4.00 12.79 15.28 hrs 10.62 hrs
2 8,820 0.306 5.00 6.90 18.77 hrs 18.77 hrs
* Total emergency storage consisting of both the pump sump (storage above high level
alarm) and incoming drains (storage between inlet inverts and overflow levels).
Note that for Pump Station 1, the time to overflow for the local catchment is
greater than for the system. The reason for this is that if PS2 is operating then it
will pump into pump station 1 reducing its storage time. If PS2 is not working
i.e. a complete area wide power failure, then PS 1 only receives effluent from
the gravity connections directly connected to the pump station catchment. This
means that the storage time will be greater than if PS2 is pumping effluent into
PS1.
As there is no other contributing effluent into Pump Station 2 its storage time
remains constant at 18.77 hrs.
Table 4 presents the emergency storages available for the pump sumps only
and could be considered the worst case scenario with no line storage included.
Woodlane Wastewater Disposal and Water Supply Preliminary Report
Wallbridge & Gilbert/070250rp002RevB/January 2008 Page 14