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Harbour Area Treatment Scheme - PTW Drop Shafts & Scum Chambers

Project data

Location: Hong Kong Island, Hong Kong

Shaft Sites

  1. Aberdeen PTW Dropshaft & Scum Chamber
  2. Wah Fu PTW Dropshaft & Scum Chamber
  3. Cyberport PTW Dropshaft & Scum Chamber
  4. Sandy Bay PTW Dropshaft & Scum Chamber

Overall Depth:

  1. Aberdeen: 9.20m
  2. Wah Fu: 22.50m
  3. Cyberport: 17.80m
  4. Sandy Bay: 18.80m

    Construction period: July - October 2014
  • Concrete lining of pre-excavated shafts; 4 No. in total

  • Construction of a rectangular Scum Chamber in each shaft

Wah Fu shaft: elliptical; with a finished lining size of 7.000m x 5.000m; other linings: circular with a finished lining size of 8.000m dia.


  • Fast construction progress, easy system operation
  • Minimum crane usage for the system
  • Form elements to follow the structure shape (circular, elliptical and rectangular)
  • Optimized element sizes, hinges and retraction devices used for stripping, no additional assembly/ modification works necessary during the construction
  • Maximum safety for workers
  • Central opening in platforms for material and manpower transfer



Leighton - LNS JV

Customer's benefit

As the contractor was required to complete all four shafts within 4 months, a proven system was required for each shaft with the following requirements:

  • Easy to use, with no skilled labour required

  • Each shaft system capable of self-climbing, sharing one set of mobile hydraulic system

  • Fast and reliable

  • Able to meet the tight programme requirements of 5 months to complete all shafts

  • Technical Supervisor to ensure a swift, trouble-free start-up


PERI solution

  • Vario GT 24 single sided wall formwork, with purpose-made shaped walers to obtain the profile
  • RCS custom made climbing platform, requiring only 4 wall anchors thus reducing setting and repair time
  • BR units inside the Scum Chambers for safe and simple support and operation