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Pass Forward

Flow Scheme

Developing a standardised approach to drive efficiencies

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The Capital Delivery Alliance (CDA) was tasked by DCWW with the design and construction of MCERT Standard pass forward flow (PFF) measurement to meet the U_MON4 driver and event duration monitors for flow to storm, EDM (U_MON3 driver), at wastewater treatment works or at last in line overflows. This is to allow the actual PFF to treatment and flows to storm to be readily checked.

PFF compliance should ensure that storm storage does not fill and discharge prematurely, preventing more frequent, higher strength, longer duration discharges to receiving waters from last in line overflows, storm tanks or other storm overflows.

Over 350 assets require installation in AMP7; DCWW have committed to completing the works by Sept 2022 to allow the data to be used to inform the PR24 Business case.


The works will ensure DCWW is compliant with new regulatory criteria, providing data on flows being passed forward to treatment, sent to storm storage and/or discharged to the environment. It will also provide reliable data on spills to storm and whether these happen before consented flows are passed forward for treatment.  The data will help determine the root cause of issues:

  1. Preventing PFF from being passed forward at the consented level.

   2. Flows to storm storage and or discharge to the environment on dry days,               when PFF maintained.

The root cause investigation can then be used to inform solution development to address the issue.

Approach – Standard design and collaborative working

DCWW agreed to carry out 20 installations and 40 designs in AMP6 so the solutions could be reviewed ready for building to start in earnest at the beginning of AMP7.

Following the AMP6 work, efficiencies were identified and standard solutions developed, utilising some of the standard CDA designs, in collaboration with DCWW.

Working Groups

There is a PFF strategy group focusing on higher level opportunities and risk reduction. There is also a PFF working group with key contributors across the different stakeholders. Given the number of assets, the geography and relatively short programme, it is essential that the team are aligned and focused on each playing their part. Communication is of vital importance and any significant delays will result in either not meeting the commitment date or an increase in cost.


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Six standard solutions (above) were developed and a clear decision map allowing an assessment of each assets. A desktop study was undertaken to determine the required solutions.

This found the solution spread for all assets and found most require 1 and 5. This is therefore where most efficiencies will be found and where he team is focusing on driving value.

With all solutions requiring ACT input, and solution type 1 requiring ACT only work at the assets, it is imperative that information provided is right first time, sufficiently detailed to minimise the need for clarification and that a communication charter is established to ensure effective and efficient use of resource.

From the 20 sites delivered in AMP6, a 40% efficiency has been realised both through reduced and standardised design and effective delivery.

To achieve these efficiencies, the CDA worked collaboratively with DCWW. By defining the route to achieving the output, we identified who and ‘when responsible teams were required in the programme of works



Want to learn more? Speak to Amelia Winslade @ MMB

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