Working with Anglian Water at Letchworth Parkwood STW


As part of M&N’s expanded servicing contract framework agreement, M&N engineers are responsible for Planned Preventative Maintenance across a wide range of inlet screens throughout the Anglian Water territory.

During a routine visit to the Letchworth Parkwood STW the team found 3 Escalator Screens to be experiencing operational abnormalities so further inspection was undertaken to make servicing recommendations for the equipment.

The initial on-site analysis identified several key repairs that were necessary to prevent costly screen failures, improve screening results and extend the lifespan of the assets. The key elements were a result of natural operational wear and included: 

  • Worn Gearbox units
  • Worn chains
  • Driven Sprockets in need of replacement
  • Chains at full adjustment


  • Disruption to operational stability had to be kept to a minimum
  • Screening operations had to be maintained
  • Refurbishment could not be undertaken on site


As it was necessary to carry out work ‘off site’ the team worked closely with Letchworth STW Optimiser Dale Patton to establish the best approach to maintain operational stability during the refurbishment & repair programme.

The team elected to stagger works over a 4-week period, at each stage leaving 2 screens ‘in operation’ whilst work was undertaken to the remaining screen at M&N’s extensive Portland workshops.  

Utilising M&N’s dedicated heavy lifting & transport vehicles scheduled work could be carried out quickly, minimising disruption to screening operations. 

MandN Crane Lorry

Once at the Portland workshops each screen was stripped and pressure wash cleaned to allow for a more thorough inspection of their working parts and the elements identified during the preliminary ‘on site’ analysis.

Anglian Water received a detailed evaluation of what was required and an advisory report recommending further action to be taken, timings & cost breakdowns.

Specialist M&N personnel undertook the individual elements of refurbishment on the Escalator Screens ensuring that each screen was refurbished and back at Letchworth Parkway within a week of removal from site.


5th Feb – Removal of Inlet Screen 1 from channel

15th Feb – Install of refurbished Inlet Screen 1 & removal of Inlet Screen 2

22nd Feb – Install of refurbished Inlet Screen 2 & removal of Inlet Screen 3

29th Feb – Final install of refurbished Inlet Screen 3

On each screen the CHASSIS was repaired and the existing GEARBOX UNIT fully refurbished. Alongside this the team supplied and fitted new DRIVE CHAINS, PLASTICS & SEALS and DRIVEN SPROCKET, all of which were covered by M&N’s 12 month Refurbishment Guarantee.

Download Letchworth Parkwood case study [547KB]