3.2.10 Wastewater Treatment Plant Overview
This section provides an overview of the Lake Bennett Community (LBC) Onsite Wastewater Management System (OWMS), based on the LBC OWMS O&M Manual V1.1 prepared by ENVR Solutions Pty Ltd.
Project location: 841 Chinner Road, Lake Bennett, Northern Territory (Lot Plan 2005/20)
Legacy System
The pre-upgrade sewerage infrastructure — including the old SSP2 distribution box and lift well, and the legacy trench-based Land Application Area — has been decommissioned and replaced by this system.
System Purpose
The OWMS sustainably treats wastewater flows that fluctuate significantly over holiday periods throughout the year to Class A recycled water quality. The system comprises three distinct subsystems:
- Wastewater Treatment Plant (WWTP) — AdvanTex® advanced secondary treatment, peak design 37,800–38,800 L/day
- Land Application Areas (LAA) — Two subsurface dripline irrigation zones (7,620 m² operational)
- Recycled Water Storage (RWS) — Four 27 kL tanks (108,000 L total) for wet-weather storage and future reuse
Treatment Technology
The WWTP uses an AdvanTex® treatment system manufactured by Orenco Systems® Inc (Orenco) and designed by ENVR. The AdvanTex® process is an attached-growth, multi-pass advanced secondary treatment method utilising naturally occurring microorganisms in anaerobic, anoxic, and aerobic environments. Key features:
- Four (4) AdvanTex® AX100 Textile Filters with upstream primary tanks and downstream RWS tanks
- Anoxic treatment tank with alkalinity dosing for effective nitrogen reduction
- Microfiltration and two-step disinfection (UV + chlorine) before discharge
- Orenco T-COM Control Panel with 4G telemetry for remote monitoring and alarm notification
Treated effluent is suitable for subsurface irrigation within two designated zones or for use in a future community nursery propagation program.
Process Flow
Collection Network (Zones 1–3)
↓
Primary Treatment (PT-1, PT-2, AT-1)
↓
AdvanTex AX100 Secondary Treatment (4 units, recirc tanks)
↓
Discharge Tank → Microfiltration → UV → Chlorine Dosing
↓
Recycled Water Storage (4 × 27 kL) / Subsurface Dripline Irrigation (LAA)
See Appendix 1 — WWTP Schematic in the O&M manual.
Plant Layout
Site Layout (Plant and LAA)
As-Constructed Services
Collection Network
Wastewater from 64 bungalows is collected via three zones:
| Zone | Bungalows | Collection Route |
|---|---|---|
| Zone 1 | 17–59 | Gravity sewer to ~18 kL septic tanks (SPS1 / SSP1), discharging to WWTP Primary Tank 1 |
| Zone 2 | 1–16 | Gravity sewer to 22 kL STEP tank (SPS2 / SSP2 replacement) |
| Zone 3 | 65–66, 75–80 | Gravity to SSP4/SSP5 septic systems → SPS3 (SSP3) → submerged rising main under lake → SPS1 |
See 3.2.2 SSP2 — STEP Tank, 3.2.1 SSP1, and 3.2.3 SSP3 for collection network details.
Design Basis
| Parameter | Value |
|---|---|
| Average daily flow | 12,000 L/day |
| Peak daily flow | 37,800 L/day |
| Power supply | 220–240 V AC, 3-phase, 50 Hz |
Influent Characteristics (avg / max)
| Parameter | Average | Maximum |
|---|---|---|
| BOD | 140 mg/L | 200 mg/L |
| TSS | 50 mg/L | 100 mg/L |
| TKN | 50 mg/L | 80 mg/L |
Discharge Targets
| Parameter | Target |
|---|---|
| BOD | ≤ 30 mg/L (max) |
| TSS | ≤ 20 mg/L (max) |
| TN | ≤ 60 mg/L (avg) |
| TP | ≤ 20 mg/L (avg) |
| E. coli | ≤ 10 CFU/100 mL (max) |
| pH | 6–9 |
Design Limits
Flows and waste strengths entering the WWTP must be monitored. If influent parameters exceed the design basis, measures must be taken to reduce them or additional treatment capacity will be required. Contact ENVR Solutions for a design review.
WWTP Components
| Component | Specification | Detail Page |
|---|---|---|
| Primary Tank 1 (PT-1) | 22,000 L concrete | 3.2.11 |
| Primary Tank 2 (PT-2) | 22,000 L concrete | 3.2.11 |
| Pre-Anoxic Tank (AT-1) | 22,000 L concrete | 3.2.11 |
| Recirculation Tanks | 2 × 15,000 L concrete | 3.2.12 |
| AdvanTex AX100 Filters | 4 units | 3.2.12 |
| Discharge Tank | 15,000 L concrete | 3.2.12 |
| Control Room | 20 ft repurposed container | 3.2.15 |
| Microfiltration | HUR 90 HP / HC/90-5 | 3.2.13 |
| UV Disinfection | Sanitron S5000C | 3.2.13 |
| Chlorine Dosing | Grundfos DDA 7.5-16 AR | 3.2.13 |
| Alkalinity Dosing | Sodium bicarbonate via Liquid Chem Feed Unit | 3.2.11 |
| T-COM Control Panel | Orenco telemetry panel | 3.2.15 |
| RWS Tanks | 4 × 27,000 L poly | 3.2.14 |
| STEP Tank (SPS2) | 22,000 L concrete | 3.2.2 |
| LAA Dripline Irrigation | 7,620 m² (2 areas) | 3.2.8 |
Prohibited Wastes
The following must not be discharged into the OWMS, as they may adversely affect biological treatment processes:
- Chlorine (pool and spa overflow)
- Waste dairy products
- Quaternary Ammonium Compounds (disinfectants, cleaning products)
- Formaldehyde (disinfectant, chemical toilet treatment)
- Dichlorobenzene (urinal tablets, sanitisers)
- Petrochemicals (waste oil, diesel, turpentine, etc.)
- Pharmaceuticals (drugs and medicines)
- Water softener brine — strongly prohibited; discharge will void Orenco's warranty
Contacts
| Role | Company | Contact |
|---|---|---|
| Designer, Installer, Remote Monitoring | ENVR Solutions | Matt McKennariey — 0402 524 033, m.mckennariey@envr.com.au |
| AdvanTex Manufacturer | Orenco Systems | +1 (541) 537-0049, bhensley@orenco.com |
| Liquid Waste Removal | McMinns Pumping Systems | 0408 895 171, mcminnspumping@pbigpond.com |
| Local Electrician | Top End Electrical | Liam Kuhl — 8945 5684 / 0438 486 603 |
| Local Plumber | Absolute Plumbing NT | Damien Mahony — 0408 234 428 |
| Site Caretaker | Lake Bennett Community | Tim Earl — 0417 892 281 |
Related O&M Manual Appendices
| Appendix | Content |
|---|---|
| 1 | WWTP Schematic |
| 2 | ENVR As-Constructed Drawings |
| 3 | Orenco Contact Details |
| 4 | AdvanTex Material List |
| 5 | Orenco Design Review Letter |
| 6 | Technical Data Sheets |
| 7–9 | Effluent Pump, UV, Microfiltration Owner's Manuals |
| 10–11 | AdvanTex O&M Manual and Troubleshooting Guide |
| 12–14 | Control Panel Specification, Wiring Diagram, T-Com Settings |
| 15–16 | Warranties, Orenco Disclosure Letter |
Full appendices are in the O&M Manual PDF.
Version Control
| Version | Date | Description |
|---|---|---|
| 1.0 | 2025-10-06 | Initial Release (legacy system) |
| 2.0 | 2026-06-22 | Updated for AdvanTex WWTP upgrade per O&M Manual V1.1 |
| 2.0.1 | 2026-06-22 | Added plant and site layout diagrams |
Next Review Date: 2026-12-22