E-N Rd Non-worsening calculations

[Sheet: Sheet1]
Estimated Flows to Rear of Property in 1% AEP Storm Events

Development Case	Description of Calculation	1%AEP flow (m3/s)	Approx. Capacity outlet pipe (m3/s)	Flow in Kerb adaptors (m3/s)	Estimated Flow to Rear (m3/s)	Comments
Current Approved Design	Capacity of 300mm diameter oulet pipe	0.193	0.33	0	0.193	Proposed 300 pipe has capacity for full 1% AEP runoff
Existing undeveloped site	1%AEP flow (100% pervious)	0.16211999999999999	0	0	0.16211999999999999	All flow presently goes to rear
Previous developed site prior to 2016	1%AEP flow (90% Imperv) - Flow in 250 pipe - flow in single kerb adaptor	0.193	7.0000000000000007E-2	2.5000000000000001E-2	9.8000000000000004E-2	Existing 225 pipe combined with kerb adaptors can cater for full 1% AEP runoff
Proposed	1%AEP flow (90% Imperv) - Flow in 250 pipe - flow in multiple kerb adaptors	0.193	7.0000000000000007E-2	0.1	2.2999999999999993E-2	Existing 225 pipe combined with kerb adaptors can cater for full 1% AEP runoff
Notes: 
1. 1%AEP flow (90% Imperv) obtained from B&W SMP Nov 23
2. 300mm dia Pipe Capacity based on orifice flow calculation assuming stagnant water in upstream pit and 2.0m of allowable pressure head
3. 225mm dia pipe Capacity Based on pipe flowing full calculation at 2% grade
4. Capacity of Kerb adaptors based on 25L/s noting that pressure head from downpipes will likely be > 2.0m even with buildings at rear