3.2.6 Gravity Mains
This section details the specifications for the sewer gravity mains and access chambers.
Zone 1 — Bungalows 17–59
- Pipe: DN150 PVC gravity main running parallel to the access road, discharging to SPS1 (SSP1) septic tank
| Chamber | CCTV | Location |
|---|---|---|
| Access Chamber 1 | MH C | Next to Bungalow / Unit 17 |
| Access Chamber 2 | MH A | Behind Unit 40 (common area between Units 39 and 40); receives Zone 3 under-lake rising main from SSP3 |
| Access Chamber 3 | MH B | Common area between Bungalows / Units 55 and 56 |
Access Chamber 2 (MH A) — Unit 40
Access pit behind Unit 40. The 40 mm lilac Zone 3 rising main from SSP3 lands here after crossing under the lake, then effluent continues in the DN150 gravity main toward SSP1. See 3.2.7 Rising Mains and 3.2.3 SSP3.
Access Chamber 1 (MH C) — Unit 17
Inside view of the Zone 1 gravity-main access pit next to Unit 17 (MH C / Access Chamber 1).
Known Issues
- Groundwater Ingress: Observed through joins in the access chamber nearest SSP1
- Sealing: Gaps present between lids and riser pipes in both chambers
- CCTV Priority 1 (6 March 2026): Pipe barrel structural grade 1. East-side Priority 1 repairs and the Unit 41 investigation are complete (Oct 2026) — see 5.2:
- Unit 39 main / connection — 5.2 Unit 39
- Unit 40 / MH A — 5.2 Unit 40
- Unit 41 branch — 5.2 Unit 41
Programme summary remains on 5.1 East Side Septic Main Repair (status Complete).
Zone 2 — Bungalows 1–16
- Pipe: Gravity sewer main to SPS2 (SSP2) STEP tank
- Note: Previously fed a distribution box and septic tanks (now removed and replaced by the 22 kL STEP tank)
Zone 3 — Bungalows 65–66, 75–80
- Pipe: Gravity sewer mains to SSP4 and SSP5 septic systems, then to SPS3 (SSP3) via 32 mm pipeline
Version Control
| Version | Date | Description |
|---|---|---|
| 1.0 | 2025-10-06 | Initial Release |
| 2.0 | 2026-06-22 | Updated Zone 2 for STEP tank; added Zone 3 reference |
| 2.1 | 2026-08-31 | Linked 2026 gravity sewer main repair |
| 2.2 | 2026-08-31 | MH A–C labels and DHE CCTV Priority 1 defects |
| 2.3 | 2026-10-25 | Unit 41 branch repair complete; Priority 1 at 39/40 still open |
| 2.4 | 2026-10-25 | Unit 40 / MH A Repair 2 complete; only Unit 39 Repair 1 open |
| 2.5 | 2026-10-25 | Unit 39 Repair 1 complete; east-side Priority 1 programme closed |
| 2.6 | 2026-10-26 | Added MH C / Unit 17 access-chamber inside photo (moved from 3.2.1) |
| 2.7 | 2026-10-26 | Renamed MH C photo file; dropped SSP1-riser disclaimer |
| 2.8 | 2026-10-30 | MH A / Unit 40 noted as landing for SSP3 under-lake rising main |
Next Review Date: 2027-04-26