Civil Engineers North Kellyville | Drainage & OSD

North Kellyville has grown from paddocks into one of The Hills Shire’s most complete new communities in a little over a decade, and it’s still building. Duplexes, custom homes, granny flats and infill subdivisions are all happening at once across the precinct. Contrive Consultants provides civil and stormwater engineering for this exact kind of work, and we’re based in Rouse Hill — one suburb over, on the other side of Windsor Road. When a North Kellyville certifier asks for a drainage amendment, we can inspect the site the same day rather than working off photographs.

Building in North Kellyville

North Kellyville was one of the first precincts released in the North West Growth Area. The precinct covers roughly 707 hectares, bounded by Smalls Creek to the west, Cattai Creek to the east and north, and Samantha Riley Drive to the south, and was planned to accommodate up to 4,500 new homes. Development ramped up through the 2010s, and today the suburb has its own shopping village, schools and a well-established street network — but pockets of larger, older lots remain, and these are steadily being subdivided or redeveloped.

From an engineering perspective, the two creeks define everything. North Kellyville’s stormwater ultimately drains toward the Cattai Creek and Smalls Creek corridors, and the precinct planning put significant weight on protecting those riparian systems. The terrain rolls noticeably — this is genuinely hilly country — so cut and fill, retaining walls, driveway grades and interallotment drainage come up on almost every job. It’s common for us to design a drainage system for a lot that sits several metres above or below its street.

The Hills Shire Council administers development here, with contributions collected under the precinct’s dedicated contributions plan, and council’s engineering standards apply to every drainage connection, OSD system and driveway crossing.

What builders need in North Kellyville

Applications for new dwellings, duplexes and dual occupancies in North Kellyville routinely require:

Stormwater drainage plans designed by a civil engineer, coordinated with the site survey and architectural levels.
On-site detention (OSD) — with much of the precinct now built out, redevelopment and multi-dwelling projects usually can’t rely on subdivision-era assumptions and need their own detention storage sized to Hills Shire requirements. Council also has clear preferences about above-ground versus underground OSD tank construction.
Easement investigation — many lots drain through interallotment easements toward the creek corridors; building over or near a drainage easement needs careful documentation and sometimes formal approval.
Driveway and access design — steep frontages regularly need longitudinal sections proving compliant grades and transitions.
Erosion and sediment control during construction, particularly on sloping sites above the creek catchments.
Supporting documents — waste management plans and BASIX certificates accompany virtually every application.

For duplex and dual-occupancy projects — a huge share of current North Kellyville work — the stormwater design is often the deciding factor in whether the site works financially. We recommend a feasibility-level drainage check before purchase or design.

Our services in North Kellyville

The Contrive group covers the full consultant list for a North Kellyville build:

Civil and stormwater engineering (Contrive) — drainage design, OSD, driveway sections, retaining coordination and certifier responses.
Traffic engineering and swept path analysis (Sweptpaths) — access reports for dual occupancies, childcare proposals and tight corner lots.
Surveying (partner company) — detail and contour surveys that capture the level changes North Kellyville is known for.
Town planning (URBA) — subdivision and dual-occupancy planning advice under the Hills LEP and DCP.
Architecture and 3D visualisation (ARQI) — duplex and custom home design that works with the slope instead of fighting it.
NatHERS/BASIX (NathersPRO) — energy assessments for new dwellings and alterations.
Waste management plans (Contrive) — construction and ongoing waste documentation.
NBN pit and pipe design (Pit and Pipe) — for infill subdivisions creating new lots.

North Kellyville FAQs

I’m building a duplex in North Kellyville — will OSD be required?

Almost certainly, yes. Multi-dwelling development in The Hills Shire generally triggers on-site detention, and council is particular about tank type and configuration. We size the storage, design the outlet control and prepare the full OSD package certifiers expect.

There’s a drainage easement through my North Kellyville block. Can I still build?

Usually, but the easement dictates your footprint. Structures generally must stay clear of the easement or be specifically justified, and your own stormwater may need to connect into the easement line under controlled conditions. We review the 88B instrument and design around it — this is bread-and-butter work for us in this suburb.

My site slopes steeply toward Cattai Creek. Does that change my drainage design?

It changes plenty: discharge energy needs to be managed, erosion controls become more important, and if you’re near the riparian corridor there can be additional setback and water quality considerations. Sloping sites are normal here and entirely buildable with the right engineering.

Start with a local engineer

Still choosing a builder for your North Kellyville project? 13 Homes is a Sydney builder we regularly coordinate designs with in the growth areas.

Before you lock in a design for your North Kellyville project, get the civil engineering questions answered — it’s cheaper in that order. Call Contrive Consultants on +61 497 848 111, email info@contriveconsultants.com.au, review our full service list, or send your plans through our contact form for a quote within one business day.

Planning a new build in North Kellyville? For new homes, duplexes and knock-down rebuilds we’re happy to recommend 13 Homes, a Sydney home builder we regularly work alongside on local projects.