3.2.7 Rising Mains
This section details the rising sewer mains used in the collection network and recycled water distribution.
Zone 3 — SSP3 to Unit 40 Access Pit (Under Lake)
| Item | Detail |
|---|---|
| Pipe | 40 mm lilac poly pipe encased in a 100 mm PVC pipe (upgraded from original DN32 HDPE Blueline) |
| Route | Submerged sewer rising main under Lake Bennett from SPS3 (SSP3) to the access pit near Unit 40 (MH A / Access Chamber 2) |
| Onward | From MH A via Zone 1 DN150 gravity main to SPS1 (SSP1), then WWTP Primary Tank 1 (PT-1) |
| Test | Pressure tested successfully (original pipe) |
Recycled Water Irrigation Mains
Treated Class A effluent is distributed from the WWTP discharge tank through the control room (microfiltration, UV, chlorine dosing) to the Land Application Areas via lilac-coloured subsurface dripline irrigation pipework.
| Main | Detail |
|---|---|
| Pipe colour | Lilac (permanently coloured, per recycled water standards) |
| Technology | Netafim Bioline 17 pressure-compensating dripline |
| Areas served | Irrigation Area 1 (1,386 m²) and Irrigation Area 2 (6,234 m²) |
| Supplier | Thinkwater NT |
See 3.2.8 Effluent Disposal for irrigation area details.
Decommissioned Mains
Legacy System Decommissioned
The following rising mains from the pre-upgrade system have been decommissioned:
- SSP1 to legacy LAA distribution box: 50 mm uPVC pressure pipe (previously exposed at ground level along access track)
- SSP2 to SSP1 causeway crossing: 50 mm PVC pipe through riser chamber sidewall (replaced by STEP tank discharging to WWTP)
Version Control
| Version | Date | Description |
|---|---|---|
| 1.0 | 2025-10-06 | Initial Release |
| 2.0 | 2026-06-22 | Updated for WWTP upgrade; marked legacy mains decommissioned |
| 2.0.1 | 2026-06-22 | Corrected irrigation area sizes per site |
| 2.1 | 2026-10-30 | Under-lake SSP3→SPS1 lilac poly corrected to 40 mm |
| 2.2 | 2026-10-30 | Under-lake route corrected: lands at Unit 40 access pit (MH A), then gravity to SSP1 |
Next Review Date: 2027-04-30