Mount Verde Estate Hydraulic Masterplan

Executive summary

Mount Verde Estate is progressing a major, phased expansion comprising 91 subdivisions (2–3 ha) and additional residential development totalling approximately 774 units. Ant Consult was appointed to produce a hydraulic masterplan to quantify demands, confirm storage needs, and propose a robust, low-maintenance bulk water configuration that prioritises operational simplicity and reliability.

The recommended concept leverages the existing municipal gravity feed (Ø160mm) and high-level storage at Plot A16 (250 kL) as the command reservoir, while using targeted offtakes, pressure management, and limited booster pumping only where unavoidable.

Client context

Mount Verde’s existing water supply and constraints included:

• Municipal supply via Ø160mm pipeline, with measured boundary pressure of ~6 bar.
• An existing Ø200mm UPVC CL12 line from the boundary to a 250 kL reservoir at the estate high point.
• Existing internal reticulation consisting mainly of HDPE PN10 (Ø50–Ø110mm).
• Planned development growth (circa 800 units total) requiring a supply services masterplan to support phasing and infrastructure investment decisions.

Objectives and scope

The appointment required:

1. Quantify and spatially allocate present and future water demands.
2. Size storage reservoirs to provide adequate buffering.
3. Identify optimal reservoir locations to minimise pipe runs while maintaining gravity head.
4. Route and size main water lines for the preferred future configuration.
5. Compare the “ideal” arrangement to the status quo and recommend strategic upgrades.

A key instruction was to prioritise ease of management and lower operating cost over minimum capital cost.

Approach (method)

Ant Consult followed a masterplanning workflow aligned with common industry practice for water supply masterplans:

• Data review and validation of supplied drawings and surveys.
• Development of planning-level hydraulic assumptions and material standards.
• Demand modelling using recognised guidance (Red Book, 2019 categories).
• Network concept modelling using preliminary ring mains to approximate final friction losses and operational performance.
• Identification of pressure and topography risks, followed by definition of mitigation measures (e.g., pressure management strategy).

Key technical assumptions (planning level)

• Pipe materials: HDPE PN10 for ≤110 mm, UPVC CL12 for >110 mm.
• Pressure management:
  • PRVs acceptable at offtakes.
  • Avoid PRVs in series (risk of “hunting” and pressure oscillations).
  • Prefer break-pressure tanks for long downhill runs.
• Reservoir control: modulating float valves (e.g., Bermad 750 series or similar).
• Design philosophy: “right infrastructure in the right place” with the fewest moving parts, minimal pumping, and minimised maintenance.

Demand and storage outcomes

The development demand profile (planning categories) included:

• Agricultural (domestic use only): 2,000 ℓ/day × 90 units
• Residential high density: 700 ℓ/day × 430 units
• Residential medium density: 900 ℓ/day × 354 units

This yielded a total annual average daily demand of ~711 kL/day.

Given the low-risk nature of the municipal gravity source and upstream buffering, 24 hours of storage was adopted as sufficient (risk-based decision).

24-hour storage requirements (recommended):

• Forest Hills reservoir: ~120 kL
• Scheme command reservoir: ~500 kL, with recommendation to double storage at the command site using a second identical tank with interconnected outlets.

Recommended masterplan concept

The recommended estate-wide configuration:

• Retain municipal gravity supply to the Mount Verde boundary (Ø160 mm, ~6 bar).
• Continue conveying supply via Ø200 mm UPVC CL12 to the existing 250 kL command reservoir .
• Address hydraulic “distance from command storage” by supplying certain regions via direct offtakes off the mainline, each controlled by a suitably sized PRV.

Firefighting considerations

• Agricultural plots fall under the local agricultural fire protection association, so no fire flow provision was included for those areas.
• Residential areas were assessed as low risk or potentially Medium Risk 2 (depending on the final development type).

Outcomes and value delivered

The masterplan provided:

• A quantified demand basis and storage sizing for phased development.
• A clear, operationally robust water supply configuration centred on gravity supply and strategic buffering.
• A pressure management strategy suited to steep topography (break-pressure tanks and limited PRV use).
• Defined upgrade triggers (survey certainty, firefighting classification, and development phasing).

Recommendations and next steps

1. Conduct a site-wide LIDAR survey to remove terrain-related uncertainty.
2. Use LIDAR to confirm the masterplan and proceed to detailed design of mainlines and offtakes, including pipeline-reservoir interfaces and air/scour valve siting.
3. Complete detailed design downstream of offtakes ~6 months ahead of each phase construction start.

Deliverables

• Hydraulic masterplan report
• Supporting drawing set