Cromwell Wastewater Options Public Engagement

The Cromwell community was asked late 2012 to give feedback on two options for its wastewater treatment upgrade. Feedback closed mid-November 2012 and more than 100 submissions were received. Thank you to everyone who shared their views. Cromwell Community Board considered your feedback at its December meeting and has decided to proceed with a resource consent application based on a treatment standard similar to Option 2. 

Background information is available in this public engagement discussion document - please note though that feedback has closed. 

Managing Wastewater

Wastewater goes either into the reticulated wastewater network or to a septic tank.

Septic Tanks

Septic tanks are not cleaned or operated by Council.

Septic tanks need emptying out every few years. The sludge removed from septic tanks can be taken by a contractor to Council’s wastewater treatment plants. Charges apply for disposing of sludge to Council’s facilities.

The drainage fields from septic tanks often require periodic maintenance. New drainage fields should have an operation and maintenance manual supplied by the installer.

How Does my Septic Tank Work?

Follow this link and find out more http://www.waternz.org.nz/documents/publications/books_guides/story_of_your_septic_tank.pdf

Overview of Wastewater Systems Managed by Council

Alexandra

The town sewerage system was established around the 1940s, at that time with a discharge direct to the Clutha River near the conjunction of the Manuherikia River. After the filling of Lake Roxburgh when the hydro dam was constructed in the mid 1950s, a treatment facility was established 500m upstream from the bridge in the area now known as Gala Grove. This plant was decommissioned in 1987 and a new plant was constructed in the Graveyard Gully area, which is still in use today. There are currently six separate pump stations within the Alexandra network. In 1987 a new treatment plant was constructed in Graveyard Gully, which is an extended aeration process (activated sludge) where the treated effluent is discharged directly into the Clutha River.

Cromwell

A piped reticulation system was introduced in the 1930s. Up until commissioning the new system, raw sewage was discharged directly to the Clutha River. Investigation into a new system started in 1975. It was decided that oxidation ponds would be suitable for this small community. The ponds were constructed at a derelict orchard south of town adjacent to the Kawarau River. These were upgraded in 2000 due to population growth. Reticulation mains service the town and in the 1990s the system was extended to Pisa Moorings, Wakefield Bayand Lowburn.

Bannockburn

In its heyday Bannockburn was the centre of gold sluicing operations and a thriving community with hotels and stores to service the mining population. A piped reticulation was introduced to the town in the 1980s under a government subsidy scheme. Most sewer pipes are installed in private property, which was common practice when the schemes were established. The Bannockburn scheme consists of one pumping station and an oxidation pond discharging to Lake Dunstan at Bannockburn bridge.

Omakau

Omakau is mainly a service town for the surrounding agricultural community. Little is known of the history but installation of a sewerage scheme was around 1965, and probably with assistance of the Central Government subsidy scheme. Prior to the introduction of a community sewerage scheme, individual septic tanks serviced the town wastewater needs. Omakau has a dedicated wastewater collection system which operates entirely under gravity discharging to oxidation ponds to the South of the town.

Naseby

Naseby is mainly a service town for the surrounding agricultural community with a number of lifestyle residents and holiday homes. Little is known of the history of the sewerage scheme but installation was around the 1960s, and probably with assistance of the Central Government subsidy scheme. Prior to the introduction of a community sewerage scheme, individual septic tanks serviced the town wastewater needs. Naseby has a dedicated wastewater collection system which operates entirely under gravity discharging to oxidation ponds to the South of the town.

Ranfurly

Ranfurly is primarily a rural service town, although, with the Rail Trail, tourism is becoming a significant money earner. Prior to the introduction of a community sewerage scheme, individual septic tanks serviced the town wastewater needs. Ranfurly has a dedicated wastewater collection and treatment system which operates entirely under gravity. The treatment consists of fine screening, primary settlement, bio-filter, oxidation ponds, and a tertiary wet-land system.

Roxburgh

The main activities of the area are farming and fruit growing. A piped sewerage reticulation was introduced to the town in 1938. At that time it is most likely that effluent had been discharged directly to the river. Oxidation ponds were established on the left bank of the Clutha River around the late 1970s. Roxburgh has a dedicated wastewater collection system, which is almost entirely domestic sourced. There are currently four separate pump stations within the Roxburgh network.

Lake Roxburgh Village

The village wastewater system was created just prior to the construction of the Roxburgh Dam in the early 1950s. Lake Roxburgh Village has a dedicated wastewater collection system operating entirely under gravity and discharging to a primary settlement tank and soakage field beside the Clutha River.

Information on Trade Waste

Trade Waste Bylaw

The Central Otago District Council Trade Waste Bylaw came into effect on 1 September 2001.  The bylaw applies to all businesses that discharge wastewater into Council sewers. The bylaw aims to protect the wastewater system from any harmful trade wastes, and ensure that the best quality of effluent is discharged into the environment from our wastewater treatment system.

Trade waste is any commercial or industrial liquid waste that is disposed of through the Council’s sewerage system. It does not include wastewater that goes into the sewer from toilets, kitchens, bathrooms or laundries in homes.

All businesses discharging wastewater into the sewer are required to apply for a trade waste discharge consent. If you are taking over an existing business, the existing consent will need to be transferred. There may also be conditions attached to the consent that you will need to be aware of.

• Central Otago District Council Trade Waste Bylaw(270kb)
• Application for Trade Waste Discharge Consent (199kb)
• Application to Transfer Trade Waste Discharge Consent (102kb)
• Trade Waste Bylaw 2001 as it applies to Food Premises Information (85kb)

For further information, please contact the Water Services Officer janis.quiding@codc.govt.nz

Frequently Asked Questions

We flush, wash and empty large amounts of water into drains once we have used the water.  This water often has other things with it - dealing to these is very important to our health and environment.  We don’t often think about all the drains and sewers we rely on, but a little care and thought can save a lot of pain and inconvenience.

Where does wastewater go?

After treatment all wastewater goes either directly into streams, groundwater or rivers or indirectly through the ground.  Things like chemicals may not be removed by treatment and can cause water pollution.

How is wastewater treated?

Most wastewater goes to shallow ponds or tanks where natural processes break down organic matter and bugs to less harmful products.  This process cannot remove everything so water leaving the treatment process can contain nutrients and chemicals.  In some towns the water from treatment is spread on the ground so plants growing there can further clean the water.

What can and can’t go down drains?

• Household wastewater from the bathroom, toilet, washhouse and kitchen can go down drains.
• Garbage disposal grinders under sinks can be connected to drains BUT these are not encouraged as they make treatment processes work too hard breaking down unnecessary scraps that are better composted. For this reason garbage grinders are NOT environmentally friendly.
• Fat, oil, paint and solvents and poisons should not be tipped down drains - these damage pipes and joints and form lumps that block drains.
• Rainwater from roofs and paving or anything else is prohibited - it overloads pumps and treatment systems causing overflows and potential for massive pollution.
• Commercial and industrial waste products are only allowed if a TRADE WASTE PERMIT is obtained.
• Antifreeze must not be tipped down drains - it is a powerful fish killer that will eventually reach streams and rivers.
• Solids such as sand, stones and ashes must never be washed down drains.

Drains and Sewers - What is mine and what is Council's?

Pipes that service one or a few houses only are called “Drains” - these are mostly in private property and are the property owner’s responsibility to look after and fix.  Larger pipes, usually in the street are “Sewers” and Council looks after these.  The property owner is responsible for looking after and clearing blockages all the way out to the sewer.  Property owner responsibilities do not stop at the property boundary.  The exception is where pipes in the street are damaged, say by heavy trucks.

What if the Council sewer causes a problem for my connection?

You or your plumber/drainlayer must contact Council immediately so that Council can see and sort out the problem.  But your plumber/drainlayer should be certain the problem is Council’s, or Council may charge you for the work.  Council may refund your costs, fix and clean up a problem if it is Council’s responsibility but only when:

• Council is called in time to see the problem
• When an itemised account is supplied

How can I look after my drains?

• Don’t put fats and oils down drains - they will build up and cause blockages.
• Don’t put solvents down drains - they may damage joints and let the roots in.
• If you get a repeat of tree roots in drains, have the troublesome section of drain replaced with modern materials.

My drain smells

Drains should not make odours.  Have your drain layer check that your drain has the correct venting.

There are tree roots in my drain

Tree roots do not usually get into modern drainage pipes that are correctly laid.  The owner of the tree is responsible for fixing the drain.  If it is your neighbour you should discuss the situation politely and reach an agreement.  If your drains are in poor condition it may not be all your neighbour’s fault.  If the problem tree is a street tree, ring the Council, or have your plumber/drain layer ring for you.  Council needs to see what is happening at the time.  Re-laying old or damaged drains with well jointed modern materials is an alternative to removing attractive trees.  Council will not sort out disputes between neighbours over trees and drains.  If relationships deteriorate seek legal advice or talk to a Citizens Advice Bureau.

I share drains with my neighbours

In some situations a number of flats or houses share a joint common drain.  It is the shared responsibility of all users to sort out and pay for problems.  Ideally you should have a written agreement with those who share the drain.

There is a sewer on my property

Sometimes sewers have to be through private property.  Council has a legal right to access these for repairs, inspection and maintenance.  Council’s agents should contact you before doing any work, although in emergency situations they may not have time to contact you.

Who can fix drains?

Only registered drain layers are allowed to work on drains.

How can I find where my drains are?

Council’s records for your property may contain a drainage plan provided by the drain layer who built your drains.  Council may also be able to provide plans of your connection to Council’s sewer.  You can ask to have copies of these sent to you at any Council office.

Can I build over a drain or sewer?

Building over drains and sewers is strongly discouraged.  You need to discuss this with your Building Compliance Officer and/or phone Council's Assets Department.

Special conditions apply to building over sewers.  This covers both buildings and other structures like retaining walls. If you build over a sewer without permission your building may suffer serious damage if the sewer needs repair.

Finding More Information

Some councils have websites contained very detailed information and you may find them useful, but please remember that not all places have the same bylaws and regulations.  Two such websites are www.ccc.govt.nz  www.dcc.govt.nz

For further information, please contact the Water Services Officer janis.quiding@codc.govt.nz