What can residents do?
There are a number of steps people can take to help manage both the quantity and quality of stormwater. These include:
- Washing your car on the lawn, this will allow water to naturally seep into the earth
- Don't hose housewashing, concrete cleaning or any other chemicals down the stormwater drain
- Avoiding tipping paints, oils and greases down catchpits - look ouit for the embossed image of the Giant Kokopu fish icon that is on stormwater catchpits
- Ensure that spa and swimming pools are discharged to wastewater system
- Avoiding the temptation to litter. Dispose all litter to rubbish bins to avoid it being washed into stormwater systems. This will also help avoiding both blockages and potential flooding.
Managing stormwater
Council manages stormwater through the following means:
- Through planning to reduce the risk of flooding to residential, commercial and industrial areas
- By regularly cleaning streets to significantly reduce the potential for contaminants to enter the stormwater system - reducing contaminants discharging to waterways
- By regularly clearing any accumulated litter and silt from catchpit grates to reduce blockages. Seasonal hot spots are identified for appropriate cleaning intervals (majority of the surface flooding is caused by blocked catchpits)
- Stormwater Solutions for Hamilton city booklet
Subdivision development increases the area of impervious surfaces. The eventual growth of lawns, trees and shrubs is important to impede and use stormwater naturally. Council maximises this natural way of absorbing stormwater through zoning, protection of green spaces and vegetation. It carries out planting and landscaping and endeavours to achieve a consistent approach to the natural environment by integrating green space with ongoing urban development of the city.
- All new properties are required to maximise ground soakage before discharging to city's main stormwater system
- Controls on earthworks, vegetation removal, site coverage, impermeable surfaces and modification of waterways are set by Council to minimise stormwater runoff and reduce environmental impacts
- Berm pits (round ones) are put in place to catch low-lying areas
- Regular inspection and maintenance of stormwater pipes and open drains is also carried out to ensure the network is adequately functional.
- Soak Up Your Stormwater booklet
Connections
Connections to the Hamilton City Stormwater System are usually arranged through a Subdivision or Building Consent process and these connections need to comply with the HCC Development Manual; which, for small and medium sized developments, is summarised in the Connections Guide.
Copies of the Connections Guide and applications for stormwater connections can be arranged through the Water and Waste Services counter on the 6th floor of the Municipal Building in Garden Place. Before applying for a stormwater connection, note the advice at Managing Stormwater above. Stormwater soakage tests under the Building Act and/or by a Professional Engineer are usually required before a stormwater connection application will be considered.
All lots should already have a stormwater water management solution when sold for further development; you can find information on existing connections at Services Plans. Where a soakage system exists or has been approved in principle at subdivision, a notice on the Legal Title will often alert the owner.
Detention of stormwater flows may be required as part of an approval to connect to Council's infrastructure.
Discharge to Waikato River
Discharge stormwater to the Waikato River is regulated by the regional council Environment Waikato. Hamilton City Council plays an active part in protecting the greater Waikato catchment in partnership with Environment Waikato. For further information on consent to discharge stormwater to the Waikato River, refer to the Environment Waikato website.
Managing stormwater on a property
Depending on your location and situation there are a number of options available. These include:
- In some areas the stormwater may be diverted to an existing soakhole or other solution. Council's Building Unit can provide guidelines for soakage work.
- Connection to existing private drains - sometimes two or more properties share a drain. In this case an easement will be required
- Connection to a public stormwater network which usuallylocated in the road reserve, public area or in some cases in private land (easement required)
- Environment Waikato allows Council to manage the diversion of stormwater to existing natural waterways, (not the Waikato River) as part of the stormwater drainage system. This only applies to residential properties that are situated near natural waterways which are managed by Council. There are also detailed requirements from Environment Waikato on the rate of discharge and the size of the pipe. However, the drainage design must be approved by Council's network engineer from Water & Waste Services Unit.
Drainage easement
Drainage easement is often established in favour of a second party in a private property. The second party could be a private property owner next door or Council.
The intention of an easement is to protect stormwater/wastewater pipes that belong to a private property or Council. The easement area is not allowed to be built over without the second party's consent. This is to prevent any potential damages to the pipe and provide adequate assess for maintenance work.
The area of the easement is determined by the size and depth of the pipe and agreed upon when it is established. It allows the second party to enter the area and carry out maintenance work when required.
The details of any easement in a private property can be identified in the property title.
Flooding or run-off
Localised flooding can be caused by:
- Most commonly - network entries are obstructed by debris, e.g., leaves in autumn
- Faults/damages in stormwater pipe that affect designed capacity and flow
- Rainfall exceeded designed service level and the flooded area is in the secondary flow-path
- Rainfall exceeded 2, 5 or 10 year return storm level and exceeded system capacity
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