Stormwater & Drainage

How to manage stormwater and drainage

What is stormwater and how does it affect you?

Stormwater is rainwater that flows over land into drains, along waterways, eventually discharging at the coast.

The stormwater flows can be greatly affected by land development. The areas of impervious surfaces (roofs, driveways and roads) increases as bush and farmland are developed into residential or commercial spaces.

Flooding, erosion of stream channels and pollution of streams and beaches are all problems that can be associated with stormwater. The Resource Management Act (1991) sets up the statutory framework for stormwater management. It aims to protect human and ecological values by preventing or mitigating the adverse effects of stormwater quality and quantity on the human and the aquatic environment. All land developers have a responsibility under this act.

Why use a constructed wetland to manage stormwater?

Stormwater sediment wetlands are constructed wetlands that are a cost effective and aesthetically pleasing way to meet the legislative and regulatory requirements of managing stormwater and drainage.

The two most commonly used stormwater sediment wetlands are stormwater retention ponds and rain gardens.

Stormwater Retention Ponds Are systems that temporarily retain runoff and then disposes of it by infiltration. These ponds can be dry (normally dry between storm events) or wet (standing pool of water) ponds.

Rain Gardens Are used to ease peak flows and to provide stormwater treatment. They are created in low-lying areas and look and function like any other garden except they are designed with specific layers of soil, sand and organic mulch. These layers naturally filter the stormwater.

These systems assume that the increase in runoff or contamination of stormwater has already occurred reducing the contaminants in the stormwater or hold runoff to reduce flooding and erosion, improving the quality of the water.

These wetlands can treat stormwater and trap sediment from:

• Residential and Commercial Developments
• Roading (new and existing)
• Towns and small cities
• Urban stormwater runoff
• Other land developments

A key component of a constructed stormwater sediment wetland is the planted vegetation (wetland plant species). The effectiveness of this is dependent on the selection and planting of the appropriate wetland plant species.

Planting native vegetation is also a stormwater management practice that can reduce the total volume of stormwater run off. Native planting provides ecological, landscape and visual benefits.

How Wetland Solutions can help

Wetland Solutions objectives when undertaking stormwater management is to improve the aesthetics, water quality, ecological function and add economic value to the development/project.

Services include:

• Consultation
• Site assessments and feasibility studies
• Design
• Consent processing
• Catchment management planning
• Strategic and feasibility studies
• Construction supervision, and commissioning.
• Resource and discharge consents
• Plant supply and planting
• Weed and pest control
• Monitoring and maintenance

Click here to contact us to discuss your stormwater and drainage requirements.