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Insert Sewer Junction Estimates

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1️⃣ New vs. Existing Sewer Junctions

🔹 For New/Proposed Sewer (Simple & Low Cost)

  • Junctions are installed while laying the new sewer pipe.
  • No additional excavation or cutting required.
  • Standard costs for pipe materials, excavation, and backfill.

🔹 For Existing Sewer (Complex & Expensive)

  • Cutting a junction into an existing sewer is far more complicated.
  • Multiple risks, unexpected site conditions, and time-consuming work.
  • Requires detailed investigation & careful estimation.

2️⃣ Key Steps for Estimating an Existing Sewer Junction

📌 Step 1: Initial Investigations

✅ Dial Before You Dig (DBYD) & Existing Sewer Records

  • Check pipe size, depth, material, and any existing encasement.
  • Identify any structures or obstacles nearby.

✅ Site Visit & Utility Locating

  • Confirm depth and access issues.
  • Look for any surface constraints (roads, footpaths, buildings, trees, other utilities, etc.).

📌 Step 2: Excavation & Shoring

✅ Excavation Method Selection

  • Standard digging (if ground conditions allow).
  • Hand digging or vacuum excavation (if working near live services).
  • Rock breaking (if required).

✅ Shoring or Benching Costs

  • If the depth is over 1.5m, allow for shoring hire costs.
  • In tight spaces, trench shields or steel shoring boxes may be required.
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📌 Step 3: Exposing the Existing Sewer Pipe

✅ Check for Unexpected Encasement

  • If the pipe is concrete encased, additional jackhammering & concrete removal is needed.
  • If the pipe is not encased, work is simpler – but confirm this with qualifications in pricing!

✅ If Sewer was Originally Bored:

  • Existing sewer may be inside a steel casing pipe.
  • Cutting the steel casing requires special tools.
  • Inside the casing, there may be grout fill (which is basically solid concrete now).
  • Breaking through grout fill is another time-consuming step.

📌 Step 4: Cutting & Installing the Junction

✅ Pipe Material Considerations

  • OPVC/DICL Pipes: Standard cutting methods.
  • MSCL Pipes: May require welding & hot works permits.
  • Concrete Pipes: May require core drilling before installing the junction.

✅ Backfilling & Compaction Testing

  • Backfilling carefully to avoid damaging the new junction.
  • Compaction testing every 150mm lift (mandatory in Sydney Water projects).

3️⃣ Hidden Costs & Risks

⚠ Unexpected Encasement – Adds extra time & labour for breaking concrete.
⚠ Traffic Control – If work is near a road or footpath, extra permits & management costs.
⚠ Deep Excavation Challenges – Requires larger machines, extra shoring, and more crew.
⚠ Disposal Costs – Any cut concrete, steel casing pieces, or grout-filled sections must be removed.
⚠ Unforeseen Delays – Always include qualifications in the estimate to allow for variations.

4️⃣ Key Takeaways for Estimating Accurately

✔ Site Conditions Matter – Confirm depth, access, and encasement status before pricing.
✔ Excavation & Support Systems – Shoring, shields, or benching costs must be included.
✔ Cutting & Reinforcement Costs – Allow extra costs if existing pipe has steel casing or grout fill.
✔ Testing & Compliance – Sydney Water requires compaction testing for reinstatement.
✔ Clearly Define Qualifications – State that the price is based on a non-encased sewer line unless proven otherwise.

📞 Need expert estimation? Contact WSE Sydney
📧 tenders@watersewerestimatingsydney.com.au
📞 +61 451 404 645

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