This class was introduced in CESMM4 to deal with rehabilitation and renovation works for underground pipelines (mainly sewers and water mains), where existing infrastructure is retained and improved, rather than new construction (which is covered under Class F – Pipework).
1. Scope
Class Y covers:
- Renovation and rehabilitation methods for sewers and water mains, including:
- Pipe bursting
- Pipe relining (cured-in-place pipe (CIPP), slip-lining, close-fit lining, spray lining)
- Pipe coating and sealing
- Segmental lining
- Ancillary works associated with renovation:
- Manhole renovation (coatings, benching, covers, step irons)
- Connections and reconnections of laterals/house sewers
- Cleaning, de-silting, CCTV inspection before/after works
- Temporary flow diversion or over-pumping arrangements
- Specialist equipment/methods required for trenchless technology and rehabilitation.
2. Subdivision of Items
Works are subdivided into:
- Preliminary & enabling works
- CCTV surveys, flow surveys, condition assessments
- Cleaning and flushing of pipelines
- Over-pumping, flow diversion arrangements
- Renovation methods
- Pipe bursting and replacement
- Slip lining
- Cured-in-place lining (CIPP)
- Close-fit lining (fold-and-form, deform-reform)
- Spirally wound liners
- Spray-applied structural linings (epoxy, cement mortar, geopolymer)
- Ancillary sewer works
- Reinstating connections to laterals
- Sealing pipe junctions
- Grouting annular space between host pipe and liner
- Manhole renovation
- Concrete repair, benching, step replacement
- Epoxy/polymer lining or cementitious lining
- Raising covers, sealing covers
- Testing and commissioning
- Air/water pressure test for water mains
- Hydraulic leak testing for sewers
- CCTV post-installation survey
3. Method of Measurement
- By length (m) → for pipe renovation methods (CIPP, slip-lining, coatings).
- By number (No.) → for manhole rehabilitation, connections, inspections, tests.
- By area (m²) → for manhole lining, benching, protective coatings.
- By volume (m³) → for grouting, sealing materials.
- Lump Sum (LS) → for temporary flow diversion or over-pumping system.
4. Item Coverage
Unless otherwise stated, items include:
- Supply of all materials, plant, and equipment.
- Surface preparation, cleaning, desilting.
- Liner installation, curing, and trimming ends.
- Reinstatement of service connections.
- Testing, commissioning, and handing over with reports.
- Traffic control, temporary works, safety precautions.
5. Notes for BOQ Preparation
- Clearly state the method of renovation (CIPP, slip-lining, bursting, coating, etc.).
- Nominal diameter and length of pipeline must be specified.
- If connections, manhole works, or over-pumping are required, include them as separate items.
- Tests (air/water/CCTV) should be measured separately.
- Distinguish renovation (improving existing pipelines) from replacement (new pipework in Class F).
6. Example BOQ Items
- Y.1.1: Cleaning and desilting of existing sewer (300 mm dia) including removal of silt/debris, measured per m.
- Y.1.2: Renovation of 450 mm dia sewer by cured-in-place pipe (CIPP), UV cured, including all resin, installation, and trimming ends, measured per m.
- Y.1.3: Reinstating 150 mm dia lateral house connection into renovated sewer including cutting and sealing, measured per No.
- Y.1.4: Rehabilitation of existing brick manhole with epoxy lining 4 mm thick, including benching repairs, measured per m².
- Y.1.5: Over-pumping arrangement for diversion of sewer flow up to 500 mm dia, including pumps, pipelines, fuel, and operation for 1 week, measured as Lump Sum.
- Y.1.6: CCTV inspection of sewer after lining, including recording and submission of report, measured per m.
- Y.1.7: Hydraulic testing of rehabilitated water main (250 mm dia) including preparation and certification, measured per No.
✅ In summary:
Class Y is specialized for trenchless rehabilitation and renovation of sewers and water mains. It includes cleaning, lining, bursting, coatings, reconnections, manhole works, flow diversion, and testing. It ensures that pipeline renewal projects can be measured systematically and distinctly from new pipeline works.
