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Network Improvements Scheme (two PS share a common rising main which…
Network Improvements Scheme
hydraulic solution
1 minute timesteps
shortest interval available within InfraWorks
at every minute interval hydraulic model identifies rule that is valid; instantaneously implemented for the next 1 minute duration
existing outstations at these sites operate via radio and signals transmitted at 5 minute intervals
improve signal frequency to allow various assets to implement control philosophy as flows within combined sewage system significant
full bore flow via the 1.8 m diameter inlet pipe is 2.5 m3/s
combined sewage network
gravity system
comprises number of large diameter sewers ( up to 1.8 m dia) which convey approx 2.5m3/s of flow during a storm
active control solution
provide additional protection to 2no of CSOs which discharge to river
PS currently has a 900 m3 tank associated with the asset situated beneath the adjacent car park
CSO tank needs to completely fill before the storm pumps operate and discharge excess flow into the river
2nd CSO is upstream of PS and provides additional flooding protection
existing duty/standby actuated penstocks at another PS restricts the gravity flows to our PS based on a flow meter and excess flow then spills over another weir, passes through 5 mm screens, enters our PS CSO tank and when this 1000 m3 tank is completely full excess flow spills over a secondary weir and gravitates to river.
proposed solution needs to instruct these penstocks to close sooner to provide additional protection to our PS
keeping existing penstock control philosophy our PS CSO spills 15 times on average per bathing season
at present penstocks close if flow exceeds 267 l/s
instruct the existing penstocks to close when our PS CSO tank starts to fill up. This 900 m3 (900,000 Litre) tank can in theory completely fill within 6 mins (2500 litre / second flow rate)
need to understand telemetry limitations
proposed solution reduces this to 11 no
permitted to spill 12no times
instruct the penstocks to close as soon as the tank fills
level within the our PS CSO tank to be relayed to other PS penstocks to either close or open them
both PS 1.22 km apart
two PS share a common rising main which discharges flows to a WRC
when both assets pump at the same time the PPF from one PS reduces below the minimum pumped rate, reference in the EA discharge permit, and this typically coincides with the PS CSO spilling
the level within the two PS to be sent to either assets to prompt the DWF pumps to either start or stop
both PS 1.12 KM apart
identify how best to modify our rule set to ensure the CSOs are adequately protected i.e. set a lower level and incorporate rate of rise
AT WWTW WITH STORM OVERFLOWS LIMITING THE MAXIMUM FLOW THAT IS FULLY TREATED, AN INCREASE IN PERMITTED DWF WILL USUALLY LEAD TO AN INCREASE IN THE OVERFLOW PASS FORWARD FLOW SETTINGS AND STORM TANK CAPACITY REQUIREMENTS.
hydraulic modelling package
scope of project
implementation of active control systems to utilize significant existing capacity within the sewer network to reduce spill frequencies at four CSO locations in line with frequencies agreed with the EA during the consent applicable period.
sentient catchment approach developed by the innovation team