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Upgrade Existing Sewer Mains

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Sewer upgrades are required when the existing main cannot accommodate future demand. This often involves increasing the pipe size to handle higher sewage flow.

📌 Example Scenario:

  • Existing sewer: 150mm
  • New sewer: 225mm
  • Upgrade length: 300m
  • Location: Urban area, under a roadway

Each project has unique challenges, making site visits crucial for accurate estimating.

1. Key Factors in Sewer Upgrade Estimates

🔹 Pipe Size & Length:

  • Designers specify the exact length of the upgrade and the new pipe size.
  • The upgrade may involve new manholes if spacing needs to change.

🔹 Depth & Excavation Constraints:

  • The deeper the sewer, the more complex and expensive the installation.
  • Excavation width depends on the pipe size and soil conditions.
  • If trench walls cannot be benched out, shoring boxes must be used for safety.

🔹 Site Constraints & Traffic Conditions:

  • If the upgrade is in the middle of a road, extensive traffic control is required.
  • Narrow streets, busy roads, or pedestrian areas complicate work planning.
  • Overhead powerlines or underground utilities require additional precautions.

🔹 Machinery & Crew Requirements:

  • The right excavator size depends on depth and material type (rock, clay, sand, etc.).
  • Additional machinery such as vacuum trucks may be needed for utility exposure.
  • Crew size must be sufficient to handle excavation, installation, and backfilling efficiently.

2. Site Visit – Why It’s Essential for Cost Accuracy

A physical inspection of the job site helps answer key questions:
✅ Is there enough space for excavation and stockpiling material?
✅ Will benching work, or do we need shoring boxes?
✅ Are there any obstacles (overhead powerlines, underground utilities, trees, structures)?
✅ Will we need extensive traffic control and road closure permits?
✅ Where will excavated material be taken, and how much disposal will cost?

📌 Site conditions significantly affect costs. A thorough inspection avoids surprises later.

3. Excavation & Shoring Costs

🔹 Depth Considerations:

  • If the sewer depth is over 3m, Level 1 Geotechnical supervision is mandatory.
  • The deeper the trench, the more expensive the excavation and safety requirements.

🔹 Shoring vs. Benching

  • If there’s enough space, trench walls can be benched to prevent collapse.
  • If space is limited (e.g., in a roadway), shoring boxes must be used for worker safety.
  • Shoring rentals and installation time must be factored into costs.

🔹 Excavator Selection:

  • Small jobs (shallow trenches): 5T–14T excavators.
  • Medium-depth sewers (2m–3m): 14T–20T excavators.
  • Deep sewers (3m–6m+): 30T–50T excavators (especially for rock excavation).

 

🔹 Material Type & Excavation Difficulty:

  • Rock excavation is significantly more expensive than clay or sand.
  • Different soil conditions (clay, shale, sand, etc.) affect digging speed and disposal costs.
  • Vacuum excavation may be required if working near existing utilities.

4. Traffic Control & Roadway Costs

If the sewer upgrade is in or near a roadway, extensive traffic management is needed:

🔹 Traffic Control Measures & Fees:

  • Traffic Management Plan (TMP) – Council approval required.
  • Road opening fees & permits – Paid to local councils.
  • Road occupancy fees – If lanes must be closed.
  • Reinstatement bonds – Refundable but must be accounted for upfront.
  • Night works (if required) – Higher labor costs.

📌 Traffic control costs can be substantial – they must be included in the estimate.

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5. Disposal & Material Costs

🔹 Spoil Disposal:

  • Excavated material cannot be reused in roads – select fill must be imported.
  • Tip fees depend on material type – general waste, clean fill, contaminated soil, etc.
  • If disposing of old pipes or concrete manholes, costs vary based on contamination levels.

🔹 Pipe & Bedding Materials:

  • Sewer mains require select bedding material (e.g., Blue Metal).
  • Pipe type (e.g. PVC, PE) impacts material costs.

6. Testing & Compliance

🔹 Level 1 Geotechnical Supervision (if depth >3m)
🔹 Compaction testing every 150mm layer
🔹 Hydrostatic or air pressure testing for new pipes
🔹 CCTV inspection of completed sewer upgrade

📌 All testing fees must be included in the estimate.

7. Summary – Estimating Sewer Upgrade Costs Accurately

✔ Confirm upgrade details from the designer – length, new pipe size, manholes.
✔ Conduct a site visit – assess space, depth, existing services, traffic impact.
✔ Plan excavation method – benching vs. shoring, excavator size, ground conditions.
✔ Account for traffic control & council fees – road opening, occupancy, reinstatement bonds.
✔ Estimate disposal costs – confirm tip fees for different materials.
✔ Include material & labor costs – select bedding, pipe materials, crew size.
✔ Factor in all testing requirements – geotech supervision, compaction, pipe testing, CCTV.

💰 A detailed and well-researched estimate prevents cost overruns and ensures profitability.

At WSE Sydney, we specialize in accurate estimating for sewer upgrade projects, ensuring all costs are properly accounted for.

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

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