Supply Chain - Sewerage - Event Duration Monitoring

The Water Industry National Environment Programme (WINEP), developed by the Environment Agency, Defra, Natural England and Ofwat, is a regulatory framework that outlines the environmental obligations for water companies in contributing to the wider national objectives for the natural environment. One of its aims is to ensure that pollution incidents resulting from spills of untreated wastewater are better monitored and managed. The most significant requirement in this context is the retrofitting of event duration monitoring at sewage treatment works. EDM records the time and duration of storm water releases into rivers, lakes, oceans, or the surrounding land from combined sewer overflows (designated as U_MON1 under WINEP), when stormwater is diverted to a storm storage facility before being returned to the treatment process (U_MON3) and recording the flow being passed forward for treatment (U_MON4). The programme

Southern Water required the delivery of UMON_4, final stages of UMON_3, and MCERTS qualification for all monitoring equipment on spill overflow points by 31 March 2025.

Initially, Southern Water contacted Trant Engineering to carry out U_MON4 and EDM installations at 20 wastewater treatment works to be completed in AMP7, with Trant having previously installed 645 EDM and U_MON monitors for Southern Water in AMP5 and AMP6.

Prior to beginning design work, detailed site surveys were carried out to establish existing assets, the details of power, communications and telemetry hardware and to ensure that the new installations would not interfere with any other site processes.  Design work was all conducted by Trant’s inhouse electrical engineers working closely with Southern Water’s team to ensure a ‘right first time’ approach.

[caption id="attachment_26776" align="alignnone" width="1200"] FFT Radar at Petersfield WwTW - Courtesy of Trant Engineering[/caption] Challenges

Installing flow metering and EDM equipment sounds straightforward but, as is always the case in engineering, challenges arise. Although the concept design was identical for each site, the detail varied depending on individual site conditions: civil works, cable ducts, flow meter positioning, power supplies and many other factors.

Initial scoping is required to identify environmental considerations, including wildlife which may need to be moved or invasive species and the effect on programme. For example, a colony of bats had taken up residence in one of the existing kiosks, but fortunately, after careful monitoring, by the time installation was due to commence the colony had moved on.

Another challenge was that completed installations had to be certified by Environmental Flow (one of only four independent MCERTS approved bodies in the UK). With so many EDM schemes being installed around the country, Environmental Flow Ltd was very busy, so any missed scheduled sign-off date could have resulted in long delays. Thus, commissioning was completed strictly to a year-long rolling programme.

Project management

Installations were made ready for switchover in a brief window to ensure that reporting time would not be compromised. Installation and commissioning at several sites were carried out simultaneously and the region was split into two sectors. Each with its own delivery team including electrical, installation along with civils, and mechanical operatives to enable the delivery to be met.

To cover all the work in such a condensed time, staff were allocated allowing back-to-back design, installation and commissioning. The programme evolved collaboratively with Southern Water as the requirements become known, and Trant was able to build, invest and recruit into the programme.

Some of the sites had a history of power outages, which created some concerns for Southern Water about potential loss of data reporting. As a result, Trant proposed to install individual uninterruptable power supplies (UPS) to maintain power for 12 hours. Southern Water decided that the additional cost presented real value in terms of security and their MCERT coordinator was sufficiently impressed to request that a UPS be installed on all the schemes, including retrofitting at those already completed.

[caption id="attachment_26774" align="alignnone" width="1200"] Instrument board including new FFT monitor, FTS monitor and storm return MAG - Courtesy of Trant Engineering[/caption] Undertakings

Running many small, live sites concurrently meant a large volume of paperwork to ensure that there was minimal interruption to normal service: risk-assessed method statements, permits to work had to be submitted in a timely manner, and this needed close cooperation between all stakeholders. Trant demonstrated organisational proficiency as further sites were given with the final 35 sites to be completed in an eight-week period to meet tight accelerated WINEP deadline of 31 March 2025. Following which, Southern Water awarded Trant a further 40 sites. Later increasing to 91.

EDM & U_MON4 Programme Supply chain: Key participants Client: Southern Water Principal designer & contractor: Trant Engineering Civil design: Godsell Arnold Partnership Ltd Electrical installation: SRE Services Ltd Civil installation: DR Clark Services MCERT inspections: Environmental Flow Ltd FFT instrumentation: Vega Controls Ltd Flow meters: Siemens Project success

Whilst Trant were completing the initial schemes, Oliver Lockwood Southern Water’s Capital Delivery Project Manager was impressed by the performance.

“The Trant team has delivered incredible work across the U_MON projects, their exceptional efforts over AMP7, successfully delivering our U_MON3 regulatory outputs, as well as the challenging U_MON4 project while simultaneously finishing the final EDM programme deliverables. The work has not gone unnoticed.

“The team has demonstrated flexibility under numerous pressures and collaborated seamlessly with Southern Water and other delivery partners. Your experience has been a significant factor to the overflow monitoring performance, and I can confidently say that the successes of these projects would not have been possible without your collective skill and dedication.”

[caption id="attachment_26775" align="alignnone" width="1200"] New Storm Return MAG Sensor at Cowfold WwTW - Courtesy of Trant Engineering[/caption]

In all, Trant completed a total of 496 EDM installations for Southern Water during AMP7 by the regulatory date of 31 March 2025 and have now delivered over 1,000 such monitoring installations over the past three regulatory periods for Southern Water.

Southern Water’s EDM & U_MON4 Programme provides full visibility of events from every overflow in Southern Water’s network as well as monitoring Flow to Full Treatment (FFT) to meet the regulatory deadlines. The works saw just under 100 sites upgraded across Kent, Hampshire, the Isle of Wight, and East & West Sussex.

The Event Duration Monitoring (EDM) Programme of works consisted of 86 sites across Devon and Cornwall, where South West Water had a requirement to install monitoring equipment on existing consented spill overflow points. This is part of a continuous improvement of South West Water’s CSO monitoring systems, and these works will enable the instantaneous monitoring of spill events across the catchment, ensuring the client has visibility of any spills that occur and the duration of the spill event. The programme

Galliford Try firstly had to survey the existing assets to ascertain the requirements for each spill point, and to verify the method of both power and communications required for each location. Project scopes were then agreed with South West Water and any third-party stakeholders including the National Grid, British Telecom and residents. Once agreements were finalised and any wayleaves required obtained through the client’s Estates team, a programme was produced for the delivery of the works.

The original programme consisted of 14 months of continuous work, however the client then requested this was reduced to five months due to the importance of the scheme. The team managed the works for both the in-house installation teams and coordinated the interface with all the third-party organisations to ensure the scheme was completed to the accelerated programme.

[caption id="attachment_11388" align="alignnone" width="1200"] (left) New ultrasonic head in existing tank and (right) new ultrasonic head at existing spill point - Courtesy of Galliford Try[/caption] Accelerated programme

To achieve the accelerated programme, the Galliford Try team had to come up with innovative solutions to reduce time throughout the programme of work. One of the main innovations implemented was the use of solar powered instrumentation on sites that would otherwise have required, costly, time-consuming, complex mains power installations. This model was specifically designed and built for the bespoke project, however since the project completion the client is now investigating the use of this specification across a wider range of applications.

The use of standard designs and Galliford Try’s off-site build capabilities were also incorporated into the delivery of the scheme to further reduce installation times on site, the use of off-site build provided a 20% reduction in on site working. This assisted Galliford Try in reducing the overall carbon footprint of their works, minimised wastage and enabled their site teams to complete the installation as efficiently as possible.

EDM Programme: Supply chain - key participants Designer & project delivery: Galliford Try Groundworks: R&R Civil Engineering Ltd Kiosks: Quinshield Ltd Instrumentation: Pulsar Measurement Solar kiosks: GT Water Technologies Preparation, planning & innovation

The project was completed nine months ahead of the programme and has provided South West Water with its highest level of spill visibility.  The project was completed with zero accidents and incidents and had a high level of public stakeholder interface supported by Galliford Try’s site operational staff and Customer Liaison team.

The project incorporated the use of solar powered technology on some of the sites where providing a new supply would affect completion dates; and by minimising the requirement for permanent power supplies, this reduced the disruption to the residents, minimised cost to the scheme and enabled the project to be completed within the accelerated timescales.

The team used off-site construction to also aid with the accelerated programme, all the instrument kiosks were fitted out prior to delivery, the team also used items from its SAFE (Safe Assembly, Factory Environment) range including instrument junction boxes and prefabricated bracketry to reduce installation time whilst maintaining a high level of quality and consistency across all sites.

Community liaison

Throughout the duration of works Galliford Try’s project and site team in collaboration with their in-house Customer Liaison Officer ensured that affected local residents were proactively informed of the works being undertaken, this allowed Galliford Try to create positive interface with the communities affected by their works. This included letter drops and face to face communication to ensure Galliford Try’s works did not have a negative impact on the people living in and around the work sites.

[caption id="attachment_11387" align="alignnone" width="1200"] New level controller - Courtesy of Galliford Try[/caption] Accolades and feedback

SWW's Performance Manager said:

“Due to the dedication of Galliford Try the additional EDM installations were completed by the very tight deadline including the delivery of the supplementary documentation. As a result of their hard work, this allowed these new installations to be included for the first time in the EDM regulatory return for 2022 giving SWW 99.6% coverage for the first time”.

SWW's Programme Manager for Devon Wastewater Projects said:

“On behalf of SWW, Galliford Try were tasked as a trusted partner with installing and commissioning 86 Event Duration Monitoring stations throughout our area of coverage. These stations are vital to ensuring SWW have full visibility for spill events from our network of Consented Sewer Overflows. Due to the importance of the scheme’s completion, SWW requested that GT completed the project with 5 months, although the original target was set at 14 months.

Their commitment, skill and knowledge along with their professionalism and dedication ensured the project was completed within the accelerated programme dates.  We found them extremely responsive, innovative and accurate throughout the project. And look forward to maintaining this approach across our portfolio of capital schemes throughout the remainder of the AMP7 programme of works’.

Awards

Galliford Try received a Bronze “Environmental Best Practise” Green Apple award for this scheme and were presented with it at the Houses of Parliament in November 2023.  The team also received a South West Water Pure award in innovation for the development of the solar powered instrument kiosk that was used as part of the scheme.

The project was completed within the 5-month accelerated programme and was delivered to budget. The overall cost of the scheme to South West Water was £868,108 this was funded as part of SWW’s Green Recovery programme of works.

Due to the success of the project, SWW are now reviewing additional spill points that require the monitoring to be installed, some of which will benefit from the standard designs, off site build and solar innovations implemented as part of the project.