Case Study

Mangere Wastewater Treatment Plant used new wastewater filtration to solve drainage issues

Mangere Wastewater Treatment Plant used new wastewater filtration to solve drainage issues

McConnel Dowell Constructors, who manage the Mangere Wastewater Treatment Plant, consulted Wholesale Landscapes on new Biofiltration bark media.

A Wholesale Landscapes customer since

Wholesale Landscapes product used

When they started using the product

A Wholesale Landscapes customer since


Wholesale Landscapes product used

First use of product



McConnell Dowell Contractors found their current Pumice media provided poor drainage which was crucial in the wastewater filtration process. This means that with their current solution the Biofilter fills with water and then creates short cutting patches, which doesn’t allow the bacteria in the biofilter to remove the odours (VOC gases).
wastewater filtration

McConnell Dowell Constructors manage the Mangere WWTP for Watercare. This site currently processes 50-60% of Auckland City’s waste, through a series of different processes, which removes waste solids, treats and neutralises the water and then discharges it safely back into the Auckland Harbour.

The purpose of a biofilter is to remove VOC (Volatile Organic Compounds) that are released as gases, during the wastewater filtration treatment process. As the waste flows through the series of processes, high levels of VOC gases are captured and filtered through the biofiltration bark media, which works to remove and neutralise the unpleasant odours.
Poor drainage with their current biofiltration system.
Our Assessment:

Due to the ongoing challenges that they were experiencing with their Pumice Biofiltration, McConnell Dowell Constructors felt they needed to explore other alternatives. Wholesale Landscapes were contacted following a recommendation from their consultant regarding a new recipe to try and mitigate their issues. The recommended recipe had too many variables and was not a proven solution, therefore we offered an alternative solution which is our Biofilm Max c/w Ocean Shell, a tested and trusted solution used by many other wastewater filtration businesses around NZ.
wastewater filtration
Biofilter cutaway
Biofilter 2 mangere WWTP
Wholesale Landscapes Biofiltration bark media is generated from two naturally derived products, Pine Bark Nuggets (derived as a forestry residue), and Ocean Shell (derived from the muscle fishing industry).

Our recommended recipe has different sizes of chipped/mulched timber at varying stages of the aging process as well as composted bark fines and ocean shell. This blend would allow for sufficient drainage while maintaining an optimum pH level.

The premium Biofilm bark nuggets encourage the bacteria within the biofilter to thrive, which assists in the removal of the VOC odorous gases. The challenge any biofilter faces is the ability to maintain a level PH for optimum performance, this is where the ocean shell as a natural source of calcium helps to assist with maintaining the level PH.
This video on wastewater collection and treatment explains the process in detail. We supply bark media to filter out VOCs at every stage of the process.

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Our Truck Volumes

3T Truck

Full truck load volumes
  • Bark: 7m³
  • Compost: 4m³
  • Supersoil: 3m³
  • Soil: 3m³
  • Shell: 3m³
  • Stone: 1.5m³

7.5T Truck

Full truck load volumes
  • Bark: 20m³
  • Compost: 10m³
  • Supersoil: 7m³
  • Shell: 8m³

11T Truck

Full truck load + trailer volumes
  • Bark: 25m³ - 65m³
  • Compost: 17m³ - 38m³
  • Supersoil: 12m³ - 29m³
  • Shell: 12m³ - 30m³

In Canterbury or other regions? We offer bulk truck and trailer load volumes throughout the South Island.

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Our Retailers

Below is a list of our retailers. Please contact them for stock and supply.

PLEASE NOTE: Not all of our products are supplied to all retailers. We can only guarantee product quality of products we manufacture.

  • Wholesale Landscapes – Stoke Yard (that's us!)
  • Stoke Garden & Landscapes
  • Bay Landscapes & Garden Centre
  • Goldpine Richmond
  • Māpua Landscapes
  • Stonescape Garden Supplies (Concrete & Metals)
North Canterbury
  • Woodend Landscape Supplies
  • Amberley Hire & Landscape Supplies
  • Hanmer Landscape Supplies
  • Garden Box – Middleton
  • Urban Paving & Landscape Supplies – Harewood
  • Pearsons Landscape Supplies – Bromley
  • Styx Mill Landscape & Nursery  – Styx
  • Mitre 10 Mega Ferrymead
  • Odering Garden Centre Christchurch - Philpotts
  • Odering Garden Centre Christchurch - Barrington
  • Mainscape Garden Supplies
South Canterbury
  • Fulton Hogan Timaru
  • Ashburton Contracting Ltd (ACL)
  • Centaland
  • CMT Group
  • Kaikōura Landscape Supplies

Pick-Up Information

We welcome pick-up of product by the public for volumes 1m³ and over. Please check your estimated trailer weight rating below. If your trailer is unable to hold the weight of our minimum pick-up volume, please book a delivery. *We require a minimum order quantity of 3m³ for any bark, compost, soil or shell products and a minimum order quantity of 1.5m3 for any stones or aggregates.

Standard trailer
(750kg limit)
  • Bark / Mulches
  • Shell
  • Compost
  • Soil
  • Stones / Aggregates
Tandem trailer
(1,500kg limit)
  • Bark / Mulches
  • Shell
  • Compost
  • Soil
  • Stones / Aggregates
Tip truck
(2,000kg limit)
  • Bark / Mulches
  • Shell
  • Compost
  • Soil
  • Stones / Aggregates

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*We will quote to the nearest cubic meter.

Recommended depths

Typically you need a finishing layer of screened soil of 100mm when working with an uneven surface. 100mm of soil will allow to even out any hollows and give enough depth to create a flat surface

A general rule for compost is to allow for the depth of the current root structure of your plants with an additional 30-50% to mix in with the base. If you’re planting into holes or filling up a vege garden  you will need to accommodate for this prior to filling up

We recommend 100mm (10cm) deep for new bark gardens and planting into bare areas. For existing gardens with some cover, we recommend 75mm-100mm (7.5cm-10cm)

Note: Barked areas for playground impact protection need to meet NZS5828:2015 standards and is calculated on the fall areas and the height of the playground. Please contact us to discuss your barked playground areas

For paths and driveways which are often exposed to car and foot traffic, we recommend 100mm-125mm (10cm-12.5cm) on newly prepared areas due to settling of product.

This excludes preparation, compaction or drainage gravel underneath. For existing areas 75mm thickness is recommended for areas needing a small top-up.