Landscape Plans for DAs: What Councils Assess and the WSUD Link

The landscape plan used to be the document nobody read: a few tree symbols, a planting list, approved. Those days are over. NSW councils now assess landscape plans hard – against numeric controls for landscaped area, deep soil and canopy cover, against tree preservation requirements, and increasingly against water-sensitive urban design (WSUD) expectations that tie the landscape drawings directly to the stormwater engineering. On many DAs, the landscape plan has become one of the documents most likely to attract a request for information.

This article explains what councils are actually assessing, where landscape plans typically fall short, and why the smartest projects treat landscape and stormwater as one integrated design rather than two consultants’ separate paperwork. It draws on the work of ARQI, the architecture, urban design and landscape studio within the Rouse Hill–based Contrive group, whose landscape architects document DAs alongside the group’s civil and stormwater engineers.

Why councils care so much about landscape now

Three policy pressures converge on your landscape plan. First, urban heat: councils across Western Sydney and beyond have adopted canopy cover targets and green grid strategies, and they implement them one DA at a time – through your tree retention, tree planting and deep soil provision. Second, amenity and character: landscaped setbacks, screening and streetscape planting are how medium-density development earns its place in existing suburbs, and assessors read the landscape plan as evidence of whether the design respects that. Third, water: runoff quality and quantity controls are now standard, and vegetated systems – raingardens, swales, landscaped detention – are the preferred way to meet them. The landscape plan sits where all three pressures meet.

What the assessor checks: the numeric controls

Every council’s development control plan (DCP) sets its own numbers, but the categories are consistent. Expect your landscape plan to be measured against:

• Minimum landscaped area. A percentage of site area that must be soft landscaping, with each council defining precisely what counts – and typically excluding driveways, decks and narrow strips below a minimum dimension. Plans fail when they claim areas the definition excludes.
• Deep soil zones. Areas of natural ground free of structures above and below – no basement, no slab, no OSD tank – with minimum dimensions and percentages, particularly for apartment development under the Apartment Design Guide. Deep soil is where basements and landscape collide, and it is the single most common landscape RFI on apartment and townhouse projects: the basement footprint quietly ate the deep soil.
• Canopy cover and tree planting rates. Many NSW councils now require a minimum number of trees (often tied to lot size or site area) and/or a projected canopy percentage at maturity, with expectations about mature tree size classes. Token planting of small ornamentals where the DCP demands medium or large canopy trees is an easy pick-up for an assessor.
• Existing tree retention. An arborist’s report typically accompanies the DA, and the landscape plan must be consistent with it: retained trees shown with their tree protection zones, and structures, services and level changes kept out of those zones. Landscape plans that show new planting inside a retained tree’s protection zone – or worse, a driveway through it – undermine the whole package.

What the assessor checks: the qualitative content

Beyond the numbers, councils assess whether the landscape design is real and buildable:

• Species selection appropriate to the locality – many councils publish preferred species lists and expect native and locally endemic species, with mature heights and spreads that suit their location (no future forest giants under powerlines, no large trees hard against footings).
• Planting detail – pot sizes, quantities, spacing and a planting schedule that matches the plan graphics.
• Functional layout – screening where privacy demands it, streetscape planting in the front setback, usable communal open space on multi-dwelling sites, and safe sightlines at driveways (this is where the landscape plan gets checked against the swept path and sight-distance work by our traffic colleagues at Sweptpaths).
• Consistency with every other drawing. The silent killer. The landscape plan must agree with the architectural site plan, the stormwater plan, the shadow diagrams and the waste management plan. A bin bay shown on turf, a raingarden missing from the landscape plan but present on the civil plans, retaining walls at different heights on different drawings – each one is an RFI.

The WSUD connection: where landscape meets stormwater

Water-sensitive urban design is the discipline of managing stormwater quality and quantity through the design of the site itself – and its delivery mechanisms are overwhelmingly landscape elements:

• Raingardens (bioretention systems) – planted, filtered beds that treat runoff from roofs and pavements before discharge. On the civil plans they are engineered systems with specified media, ponding depths and outlets; on the landscape plan they are planted beds needing species that tolerate both inundation and drought.
• Vegetated swales – grassed or planted channels that convey and treat flows.
• Permeable paving and infiltration areas – reducing runoff volume while serving as usable surface.
• Rainwater re-use – tanks (often BASIX-driven) plumbed to irrigation, connecting the water balance to the planting design.
• Trees as infrastructure – canopy intercepting rainfall and passively irrigated tree pits taking street runoff.

Councils increasingly require WSUD measures through DCP controls and stormwater codes, and on larger projects ask for water quality modelling to demonstrate pollutant reduction. Here is the practical point for developers: every WSUD element lives on two sets of drawings. The raingarden is simultaneously a stormwater asset (sized by the engineer for treatment and hydraulics) and a landscape asset (planted, maintained, and counted – or not – toward landscaped area). When landscape architect and stormwater engineer work separately, these elements drift apart between drawing sets: different sizes, different locations, planting that would kill the hydraulic function, or a raingarden placed in the deep soil zone it just disqualified. When they work together – as ARQI’s landscape architects and Contrive Consultants’ stormwater engineers do within one group – the WSUD elements are designed once, documented consistently, and defended easily at assessment.

Common landscape plan failures – and how to avoid them

• Deep soil eaten by the basement. Resolve the basement footprint against deep soil requirements at concept stage, not after the parking layout is locked. Sometimes losing two basement spaces buys an approvable scheme.
• Landscaped area arithmetic that doesn’t survive checking. Measure to the council’s definition, show the calculations on the plan, and exclude what the DCP excludes.
• Trees without room to grow. Canopy trees need soil volume and clearance from structures and services; assessors know a tokenistic tree symbol when they see one.
• Ignoring the arborist. Tree protection zones are design constraints, not suggestions – and consent conditions will enforce them during construction.
• WSUD as decoration. A “raingarden” drawn without engineering behind it invites the stormwater referral to unpick it. Real systems, jointly documented, pass.
• Unmaintainable ambition. Councils (and future owners) are alert to landscape schemes that will die within two summers. Sensible species, irrigation from the rainwater tank, and realistic maintenance access all read as credibility.

Sequencing landscape design in your DA program

Bring the landscape architect in when the site plan is still movable – at concept design, alongside the stormwater strategy. The critical early decisions (basement extent versus deep soil, tree retention versus demolition plan, WSUD strategy, driveway location versus street trees) are all site-planning decisions. Landscape documentation drawn over a finished architectural scheme can only decorate whatever survived; landscape design done with the architecture shapes a scheme that meets the controls by construction rather than by exception. On planning-pathway questions – which controls apply, where variations are arguable – the group’s planners at URBA set the targets before the drawing starts.

Frequently asked questions

Do I need a landscape architect for a duplex or townhouse DA?

Most NSW councils require a landscape plan prepared by a suitably qualified person for multi-dwelling development, and many now require one even for dual occupancies. Beyond the formal requirement, the numeric controls – landscaped area, deep soil, tree planting rates – are precisely where small-site designs get caught, so professional documentation usually pays for itself in avoided RFIs.

What counts as deep soil, exactly?

Broadly: an area of natural ground with no structures above or below – no basement, no OSD tank, no slab – meeting your council’s (or the Apartment Design Guide’s) minimum dimensions and percentage of site area. Definitions vary in detail between instruments, so check the applicable control. The practical test is simple: if anything built sits under it, it almost certainly is not deep soil.

Can a raingarden count toward my landscaped area?

Often yes – vegetated WSUD elements are soft landscaping in many DCP definitions – but it depends on the council’s wording and the element’s design. What a raingarden generally cannot do is sit within a required deep soil zone if it has an engineered base or underdrainage. This is exactly the kind of dual-role question that gets resolved cleanly when the landscape and stormwater designers share an office.

Who maintains WSUD systems after completion?

For most private developments, the owner or owners corporation maintains on-site systems, usually under a positive covenant or maintenance schedule required by consent conditions – similar to OSD arrangements. Design for that reality: accessible layouts, robust planting and a clear maintenance schedule lodged with the plan make the obligation practical rather than theoretical.

Landscape and stormwater, designed as one

ARQI (arqi.com.au) provides landscape architecture, urban design and architectural services within the Contrive group in Rouse Hill, working beside the group’s stormwater engineers, traffic specialists and planners so your landscape plan and WSUD strategy arrive at council as one coherent package. See the group’s services or contact us: +61 497 848 111, info@contriveconsultants.com.au.