Stonbury were contracted to complete internal and external refurbishment works to a large clean water reservoir. To ensure minimal disruption and uninterrupted service, Stonbury were challenged to complete all refurbishment works in a timely manner. As a twin compartment reservoir, half of the reservoir was kept in service at all times.

Scope of works - Internal

  • Remove the existing joint material containing asbestos
  • Preparation works to joints and columns with HPWJ and Von Arx floor scabbler
  • Preparation works to internal pipework and steelwork
  • Fill joints with an approved cementitious repair mortar
  • Apply overbanding to all internal joints
  • Apply approved cementitious render coating to all columns
  • Apply approved polyurethane coating to all pipework and steelwork
  • Remove and replace stainless steel stair treds to the main access staircase

Scope of works - External

  • Remove the overburden from the roof and store adjacent to Reservoir No.1
  • Preparation of the full roof area by high pressure water jetting
  • Minor concrete repairs to localised areas
  • Application of bonded sheet membrane to complete roof area
  • Application of deckdrain to the complete roof area
  • Complete reinstatement of the roof area incl grass seeding

The reservoir was a particularly deep asset and so extra precautions were taken when working at height, specialist scaffoldings were also erected to facilitate the works. Appropriate safe systems of work were applied for safe entry and exit to the confined space. A fall arrest tripod and winch were installed for use.

As half of the reservoir remained in service for the duration of the works, extra precautions were considered, due to working over live on the reservoir roof. Any potential damages caused to the roof slab directly or to any existing joint material, where ingress could be a possibility, Site Operatives were instructed to stop works immediately and report the damages. Where necessary, immediate repairs were carried out.

After the floor and wall joints were resealed with the joint overbanding system, the columns were then rendered to prevent further deterioration and provide the required protection. Pull-off tests were carried out to ensure all coatings had sufficiently adhered. All temperatures were also recorded, to ensure the coatings were applied as per the manufacturers IFU (Information for Use).

Pipework and steelwork were then coated, using the same systems. All products used in the reservoir were approved for use with potable water and in accordance to DWI Regulation 31. After the required amount of cure time, the reservoir was ready for clean and final chlorination, before returned to service.