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Insert Sewer Junction Estimates
🔹 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.
📌 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
