Working with Southern Water at Whitewall Creek WwTW

Hydro International provided Southern Water with a complete inlet works screening and screenings handling package that boosts performance and reduces OPEX and TOTEX costs.

Situation

Southern Water’s Whitewall Creek WwTW serves a population of 85,000 in the catchment area of Rochester, Kent. Operational fatigue, high levels of grit and H₂S corrosion due to the Works' proximity to the coast meant that long-standing screening equipment had reached the end of its serviceable life.

Southern Water looked to replace the existing equipment with the latest in Screens and Screenings Handling technology and invited Hydro International's UK Wastewater Services team to look at options. In 2015 the team completed an upgrade to the Inlet Works which involved the supply and installation of two escalator screens, two wash presses, an overhead launder complete with grit trap and a new MCC to control the equipment.

Objectives

Provide a complete package of screens and screenings handling solutions by working with the team's manufacturing partners.
Design a layout that would ensure ease of maintenance & servicing going forward.
Overcome natural hydraulic challenges on site.

Solution

Following a review of the relevant information and discussions with Southern Water operations, engineering and procurement the team brought together manufacturing partners FSM Frankenberger GmbH & Co, Kuhn GmbH and in-house design teams to put together a packaged solution best suited to the site’s operational requirements and budget.

With the issue of the site being hydraulically challenged design engineers used specialist software to assess the hydraulics and ensure the final screening solution was designed to ensure no issues occurred downstream of the proposed new screening equipment.

A package of two FSM Frankenberger 1,200 mm FRS III Escalator Screens and two Kuhn HD 300/1200 Wash Presses were selected to comprise the Screens and 4.5 m³/hr Screenings Handling requirements of the new design.

In preparing layout options to ensure ease of future equipment maintenance and servicing, it was also necessary to take into account the potential impact of grit and stone capture in the launder flow.

An Inline Grit Trap was incorporated into the design package to capture as much of the grit and stone as possible. This was also factored in to extend the brush life of the Kuhn Wash Press. The launder arrangement, including the FSM Escalator Screen interfaces with the launder and grit trap was modelled using the team's 3D CAD software to ensure there would be no issues at key interface points, cutting the installation time of the final package on site.

The team's specialist Controls & Automation division fabricated a custom MMC to serve the new equipment, incorporating dedicated PLC software and telemetry.

All aspects of the mechanical and electrical installation were undertaken by the UK Wastewater Services team and completed over a 4 week period.

Outcome

In 2018 the team's engineers undertook an inspection of the performance of the plant at Whitewall Creek. Despite the naturally high levels of grit in the channels feeding the screens, since the 2015 installation Southern Water have not required any spares for the inlet screens. Screens and screenings handling performance had been maintained over the period, with the following run hours recorded for the equipment:

FSM FRS III Escalator Screens - 3,800 hours run
Kuhn KWP Wash Presses - 420 hours run

Project Summary

The team's collaborative approach, exclusive relationships with key manufacturing partners, extensive in-house resources and expertise provided Southern Water with a complete inlet works screening and screenings handling package that: