Chirton Water Treatment Works – Sand Filtration

ACWA was approached by Wessex Water to help with the replacement of the iron removal filtration system at Chirton WTW, located on a small borehole supply near Devizes.

In addition to the Sand filters, a single GAC filter was also required to dechlorinate the clean backwash water to ensure the discharging dirty backwash water meet Wessex Water discharge requirements.

In line with Wessex Water’s detailed requirement, ACWA’s contract involved the design, Installation, Testing & Commissioning of 3No Sand Filters complete with Automated backwash and air scour systems. Each Sand Filter is Ø3.0m x 2.0m Tan / Tan which an operating bed depth of 0.9m. in addition there was a GAC Filter was Ø2.6 m x 2.0m Tan / Tan and filled with Carbon.

All the vessels were connected with stainless steel 316 manifold pipework running between the vessels on common goal post supports with the feed, discharge and backwash connections rising up to flanged connections.
The system was designed to enable access to the vessels and corresponding control valves from the front without the need for access steelwork.

Each Sand Filter vessel is filled with a base of supporting 6mm stone and 6/14 sand with a filtration bed of 16/30 sand.

Technical Overview

Design basis:

  • Mechanical and Instrument Supply Project
  • Flow – 116m3/h (2.784MLD)
  • Purpose Iron Removal
  • Meets WW Design Specifications
  • Complies with DWI Regulations

The Benefits

ACWA’s solution is:

  • Designed to minimise the overall filter footprint
  • Built with redundancy for future treatment flow requirements
  • Simple to access, operate and maintain