Early and detailed civil design for a rural Blenheim subdivision

RISEN was engaged to support the planning and design of a proposed residential subdivision on an approximately 1.3 hectare site in rural Blenheim.

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The work combined early subdivision planning with a detailed assessment of the civil infrastructure required to support the development. This included wastewater, potable water, stormwater, access, power, communications and wider site constraints.

 

Understanding the site

RISEN reviewed Council records, topographical information, historic aerial imagery, utility plans and the developing subdivision layout.

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Most of the site was considered suitable for residential development. Steeper land along one boundary, nearby flood mapping and existing utility services were identified and allowed for as the design developed.

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Designing the subdivision infrastructure

Existing public wastewater and water mains were identified along the road frontage. RISEN assessed possible connection points and identified the capacity and level checks required before construction design.

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Stormwater was the main servicing challenge. There was no existing reticulated stormwater connection and the roadside swale required improvement to support the proposed development.

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The preliminary design included upgrading the swale and installing a dedicated piped stormwater system alongside the road. The preferred alignment followed the existing berm and swale towards a suitable downstream discharge point, reducing the amount of road excavation and reinstatement required. Onsite soakage was also considered but was not preferred due to the scale of the development and the level of reliance it would place on ground infiltration.

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Power, fibre and telecommunications services were also reviewed, with existing networks available near the property boundary.

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Access and subdivision layout

Different access and internal road arrangements were considered as part of the subdivision design.

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A looped internal road was preferred because it provided clearer vehicle movements, improved circulation and better opportunities for pedestrian access. The existing road entrance could largely be retained, subject to minor improvements for visibility and nearby services.

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The outcome

The work confirmed that the site had good potential for residential subdivision and provided a clear basis for progressing into detailed engineering design.

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The assessment established:

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• a preliminary subdivision and access layout

• wastewater and potable water servicing options

• a piped stormwater alignment and roadside swale improvements

• utility connection requirements

• geotechnical and flood considerations

• the further investigations needed before construction

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This allowed the wider project team to develop the subdivision around the actual site and infrastructure constraints, reducing the risk of major changes later.

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Services provided

Subdivision planning, early and detailed civil design, three waters assessment, stormwater concept design, roadside drainage improvements, utility investigations and access planning.