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Disuse Existing Water Mains

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When working on projects that require the removal, decommissioning, or diversion of an existing water main, it is essential to understand the scope and all associated costs. These jobs typically arise when:

  • An existing water main is outdated and no longer meets requirements.
  • A new development or infrastructure project conflicts with the existing water main alignment.
  • A larger capacity main needs to be installed, requiring removal or abandonment of the existing one.

In such cases, the existing water main must either be disconnected and abandoned in place (grout-filled) or completely removed from the ground. Each option comes with its own set of challenges and cost considerations.

1. Disconnection & Grout Filling (No Removal from Ground)

One approach is to disconnect the existing main and grout fill it without removing it from the ground. This method is often chosen when:

  • The existing pipe does not interfere with new infrastructure.
  • There is no risk of the abandoned pipe collapsing.
  • A cost-effective solution is needed compared to full removal.

However, several factors must be considered in this method:

  • Laser Bore Grout Calculation: The volume of grout required depends on the total length and diameter of the pipe.
  • Concrete Company Minimum Charges: Even if only 0.5m³ of grout is needed, suppliers will typically charge for a full 4m³ batch.
  • Injection Points & Site Preparation: The exact start and end points of the abandoned main must be determined to ensure a proper grout fill.
  • Proper Disconnection & Sealing: The main must be capped off correctly to prevent any potential contamination.

2. Full Removal of the Existing Water Main

In cases where the existing main must be entirely removed, the job becomes more complex and requires additional planning and site management.

Excavation Along the Old Pipe Alignment

  • The old main must be dug up along its entire length, requiring careful coordination.
  • If the main is under a road or footpath, traffic control measures will be necessary.
  • Working near live traffic can complicate excavation and extend project duration.

Traffic Control Costs

  • If the main runs along a live road, the job will require approved traffic management plans.
  • Road occupancy fees, council permits, and detour signage may be required.
  • Costs increase if excavation must be done during night works due to high traffic areas.

Saw Cutting, Driveways & Kerb Reinstatement

  • If the pipe runs under driveways or footpaths, saw cutting will be required before excavation.
  • Once the old main is removed, those sections must be properly reinstated.
  • Temporary road plates may be required to allow vehicle access while work is ongoing.

Tree & Plant Removal

  • If the existing alignment has trees, grass, or garden beds, they may need to be removed.
  • Some councils require tree replacement fees or landscaping reinstatement.
  • If tree removal is needed, it should be either properly included in the estimate or explicitly excluded.

Spoil & Disposal Costs

  • Once pipes are removed, they must be disposed of at an approved waste facility.
  • Proper allowance for tipping fees and transport costs must be made.
  • If trench backfill material is not reusable, imported fill material will be required, adding cost.

Site Visit & Alignment Assessment

Before estimating a job, a detailed site visit is essential to properly assess:

  • The alignment of the existing main and whether it passes through private property, council land, or road reserves.
  • The presence of trees, driveways, or other obstructions that could increase reinstatement costs.
  • The condition of the existing main to determine whether full removal or grout filling is the best option.
  • The proximity to other underground services to ensure safe excavation.
  • The need for additional approvals or council permits.

A proper Dial Before You Dig (DBYD) assessment should also be carried out to identify all underground services before excavation begins.

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Why These Jobs Must Be Priced Carefully

Disusing or removing existing mains involves more than just excavation and pipework. It includes a range of additional costs, such as:

  • Traffic Control & Council Permits (if working along a live road).
  • Saw Cutting & Driveway Reinstatement (if the alignment runs under private access points).
  • Tree & Landscape Removal Costs (if working in a vegetated area).
  • Tipping Fees & Spoil Management (for old pipe disposal).
  • Labour Costs for Grout Injection & Capping (if grout filling is the chosen method).
  • Temporary Road Plates (to maintain access for vehicles if needed).

It is crucial to account for all these variables in the estimate, as missing even one factor can lead to underestimated costs and project delays.

WSE Sydney – Experts in Existing Main Disuse & Removal

At WSE Sydney, we specialize in accurate cost estimation for water main removal and disuse. Our estimates cover:

✔ Grout filling calculations for abandoned mains.
✔ Excavation & removal costs, including disposal fees.
✔ Traffic control, road permits, and council fees.
✔ Proper reinstatement of affected areas (driveways, footpaths, and vegetation).
✔ Spoil management & tipping allowances.
✔ Site visits & alignment assessments for accurate pricing.

📧 tenders@watersewerestimatingsydney.com.au
📞 +61 451 404 645

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