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During the initial design phase, Davis Ogilvie approached Azwood for a custom rain garden media to work with their landscape design. They also had to be conscious of potential weather events such as high rainfall and droughts that are often seen in the Nelson Tasman area.


The Richmond West Development in Tasman is a 1500+ home residential development on the outskirts of Richmond. For this project, we partnered with Davis Ogilvie Engineers, Taylors Contracting, Tasman District Council and Manaaki Whenua Landcare Research to come up with a rain garden solution for the residential streets of their new subdivision.

Azwood's BioRetain rain garden media provided a customised solution to the specific project requirements and they handled the council approval directly which saved us time. I recommend BioRetain as a rain garden media.

Davis Ogilvie


Nelson Tasman is susceptible to long dry summers as well as wet weather events, making it hard for plants to grow.


With rainfall data, testing results and the environmental conditions within the subdivision, Azwood created a bio-retention media which effectively filters stormwater and road surface runoff while allowing the plants growing within the rain gardens to thrive.

Azwood worked through the necessary project specifications to ensure a range of recipes were suitable. From here, our technical team conducted in-house testing along with independent laboratories to analyse plant health and create a solution specific to Nelson’s long dry summers, and wet winters.

BioRetain ingredients are project-specific. Generally, mixes contain washed sand, composts, screened soils and other additives. This specific blend was created with the issues in mind as well as the local climate.

When is a rain garden beneficial to a project?

BioRetain prevents erosion and scouring of streams and rivers by moderating flooding, peak flows and spills. It also reduces water pollution by removing suspended solids, nutrients and dissolved metals contaminants from stormwater runoff. Bio Retain is also developed with local climate considerations so that in the drier months plants can thrive in a moist and nutrient-rich environment.

That being said BioRetain is a great option when developing gardens and landscaping near roads, built-up areas or on urban sites and is utilised by local government, large-scale contractors and land developers for stormwater management.

Everything you need to know about rain garden media


Tasman District Council (TDC) were pleased with how Azwood endeavoured to meet Council’s specifications as set out in our bio-retention Practice Note, including having the media independently tested by Landcare. 

Azwood worked with Council and developers/contractors to develop a bioretention filter media using locally sourced components. TDC is confident that it has met the general specifications as well as site-specific requirements in Richmond.

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