PREVENTING WASTEWATER OVERFLOWS

Transcription

1 Te Whakakorenga Whakakino PREVENTING WASTEWATER OVERFLOWS Aukatia te waipara e maringi noa ana PREVENTING WASTEWATER OVERFLOWS I

2 How you can help to prevent costly sewer blockages and wastewater overflows. Pehea e taea ai e koe te awhina REPORT POLLUTION TO TAURANGA CITY COUNCIL PH (07) Information in this book is correct at the time of publication April 2011

3 CONTENTS Introduction 1 How your sewer system works 2 It s a big cost to us all! 3 What does a wastewater overflow look like? What can cause a wastewater overflow? What is a gully trap? INTRODUCTION Tauranga City has around 1200 kms of wastewater pipe network, 10,000 manholes and 140 pump stations. These sewer pipes carry the waste from houses and businesses to be treated at the City s Wastewater Treatment Plants. Once this waste has been treated, the treated water component is discharged into the sea and the treated biosolids are taken to a consented landfill for disposal. Wastewater overflows protecting your health How you can prevent blockages and overflows How Council responds to blockages and overflows If blockages or breaks occur in the network the result can be raw sewage flowing into our harbour. Overflows are a health risk and beaches may be closed to the public. Overflows are expensive to clean up and cost ratepayers thousands of dollars every year. What you wash down the sink or flush down the toilet is pumped to the treatment plants. Every year in Tauranga foreign objects, fats and oils, rags, towels and nappies cause blockages that result in overflows. This booklet gives you important information on ways you can reduce the risk of causing sewer overflows. EVERY YEAR THE TWO WASTEWATER TREATMENT PLANTS PROCESS AROUND 10 MILLION CUBIC METRES OF WASTE. Chapel Street Wastewater Treatment Plant PREVENTING WASTEWATER OVERFLOWS 1

4 1. HOW THE SEWER SYSTEM WORKS Anei ta te punaha tuku para mahi Your house or business' wastewater pipes are called service lines (or private lines). These service lines run from various sinks, showers and toilets in your home or business to connect with the public wastewater network. The public wastewater network includes pipes and pump stations which take wastewater from houses and businesses to one of two wastewater treatment plants in the city at either Chapel Street or Te Maunga. The service lines are the property of the homeowner and the maintenance and operation of them is the responsibility of the home owner. Operation and maintenance of the public network is the responsibility of Tauranga City Council. Every time you flush your toilet the wastewater can travel many kilometres, through one or more pump stations before arriving at one of the treatment plants. Treatment plants then have to screen and process all of this waste before it can be disposed of. Our treatment plants work primarily through biological processes, with good bacteria eating bad bacteria. Unfortunately many items like gloves, wipes and disposable nappies are also flushed away. Items like this are not biodegradable so they have to be screened and removed before treatment continues. This adds cost and complexity to the treatment process. These items should be disposed of in your domestic rubbish. Once waste has been treated to remove harmful chemicals, bacteria, viruses and other nasties the treated wastewater is discharged into the sea. Gully trap Wastewater manhole Council main wastewater line 2 BEST PRACTICE GUIDELINES FOR STORMWATER POLLUTION PREVENTION

5 2. IT S A BIG COST TO US ALL! He nui te utu ki a tatou katoa It costs the Council a great deal of money to clear blockages and clean up overflows created by residents who treat the sewer system as a rubbish dump. These costs are funded as the wastewater component of the rates. Regular clearing of pipes cost thousands of dollars every year. Cleaning up after a sewer overflow A single overflow alone can cost over $5,000 for investigation, clean-up and water quality monitoring. If beaches have to be closed this will be inconvenient for beach users, events may also have to be cancelled and this all costs Tauranga City, and therefore you, money. There are also significant environmental costs for aquatic life and health risks for the public. Flushing items such as latex gloves, rags, cotton buds, nappies, medical wipes and other foreign objects down the toilet can result in the blocking of pumps at pump stations. The cost for unblocking or repairing a single pump can be over $3,000. Clearing a blockage can cost thousands of dollars Remember that everything you put down the drain has to be treated and it s a very expensive business. The less water you use, the less wastewater you create. This means you'll pay less for wastewater treatment (in your rates) and less on your water bill. If a blockage occurs on your property then you or your landlord will have to pay the cost for a plumber to fix the problem and this could be hundreds of dollars. WASTEWATER OVERFLOWS COST YOU, THE RATE PAYER THOUSANDS OF DOLLARS PREVENTING WASTEWATER OVERFLOWS 3

6 3. WHAT DOES A WASTEWATER OVERFLOW LOOK LIKE? Pehea te ahua o te waipara, maringi noa? Sewage spills can range from just a trickle of wastewater to a very noticeable gushing from a manhole or gully trap. As a general rule in Tauranga wastewater manhole covers are painted white (stormwater manhole lids are generally painted blue). If the leak is underground wastewater may be visible bubbling up through the ground. For serious overflows solids and toilet paper may be visible. Minor overflows may look more like a water leak. Usually with overflows there is an unpleasant odour. Look for: Back-ups in drains inside your home. Broken sewer pipe discharging wastewater to an open drain Water leaking around manhole lids onto your property or the street. Leaking water from outside drains and gully traps. Water bubbling up from underground. Unusual foul smelling wet areas which may have deposits of faecal matter, toilet paper or sanitary products. Manhole overflowing due to a blockage IF YOU NOTICE ANY OF THESE SIGNS CALL THE COUNCIL IMMEDIATELY PH (07) BEST PRACTICE GUIDELINES FOR STORMWATER POLLUTION PREVENTION

7 4. WHAT CAN CAUSE A WASTEWATER OVERFLOW? He aha tera i taea ai te maringi noa o te waipara Although some wastewater overflows are caused by defects in the network, the majority of overflows are caused by residents flushing things they shouldn t down the sink or toilet. 4.1 Foreign Objects Your toilet and sink are not rubbish disposal units. If it is not wastewater from your toilet, sink, shower or washing machine, then it should NOT be going down the pipes. Your wastewater (or sewer) pipes are designed only for wastewater to be collected. Avoiding blockages also means avoiding plumbing bills. Causes of wastewater overflows in Tauranga 24% Cause unknown 6% Tree roots 10% Third party damage 20% Foreign objects 12% Network faults 28% Fat PREVENTING WASTEWATER OVERFLOWS 5

8 Do not flush any of the following: Kaua e tukua kia rere te wai mo enei e whai ake nei Strong chemicals Wood Rocks and concrete Plastic wrapping Cigarette butts Kids toys Cotton buds Dental floss An entire deep fryer retrieved from a sewer line Disposable nappies Medical wipes Condoms Feminine hygiene products Towels Rags Baby wipes Clothing Underwear Surgical gloves Kids toys caused a blockage and an overflow to the harbour Fats or oils Waste engine oil Anything else that is not organic/biodegradable COTTON BUDS, DENTAL FLOSS, NAPPIES AND BABY WIPES CAN ALL CAUSE SEWER BLOCKAGES Rags flushed down the toilet blocked a wastewater pump station 6 BEST PRACTICE GUIDELINES FOR STORMWATER POLLUTION PREVENTION

9 4.2 Fats, oils and grease Nga momona, nga hinu me nga pera Hot fat, oil and grease tipped down the sink do not travel far before they cool down and solidify resulting in pipe blockages. Tipping hot water down the sink just moves the problem further down the system. Collect cooled fats, oil and grease in a covered container, plastic bag or newspaper and dispose of it in the rubbish bin or put it in the compost bin or worm farm. Restaurants and other food premises are a significant source of grease and fat that are used in cooking. These businesses must have a grease trap plumbed into their waste system to collect fats and oils. Tipping fat down the sink and washing it through with hot water only moves the problem down the system 4.3 Tree Roots Nga take rakau Tree roots find their way into the wastewater network through joints in the pipes (older pipes in particular). The roots cause blockages as they grow and restrict the flow in the pipe. This can result in the tree needing to be removed. If the tree is on private land and is causing problems in the wastewater network, then the cost of tree removal may be charged to the landowner. Before planting a tree, owners should consider the likelihood of that tree causing damage to underground pipes. Choose plant locations carefully. Tree roots growing into manholes or pipes can cause blockages PREVENTING WASTEWATER OVERFLOWS 7

10 4.4 Third party damage Ngaa roopu tuatoru whakakino 4.6 Inflow and infiltration Te paringa me te urunga mai Contractors can damage or break sewer lines. Heavy machinery or directional drilling can damage pipes and contractors may not be aware of the problem. Everyone working around sewer pipes must know where they are located to ensure they are not damaged. 4.5 Vandalism Mahi taurekareka Exposed wastewater pipes can be damaged or broken by vandals, and there have been cases of manhole covers being removed and foreign objects deliberately dumped into the wastewater network. During heavy rain, sewer drains can become overloaded when stormwater enters them, causing overflows. Often the overflows are caused by stormwater entering cracks and breaks in private sewer drains that connect to Council pipes. Inflow from house gully traps during heavy rain is a big contributor. Infiltration is the entry of groundwater and stormwater into sewer pipes below ground, which can substantially increase the wastewater flow in the pipe. It can also contribute significantly to wet weather flows. Council is actively trying to reduce this by undertaking inspections of residential gully traps, and working with residents to remedy any problems found. Hundreds of rocks deliberately dumped in a sewer manhole. This caused a major overflow Overflowing sewer manhole during heavy rain 8 BEST PRACTICE GUIDELINES FOR STORMWATER POLLUTION PREVENTION

11 5. WHAT IS A GULLY TRAP? He aha te awaawa rerenga wai Gully traps are small drains, usually located beside your house s foundations, outside your kitchen, bathroom or laundry. It may have a grate or cover over it to keep out leaves and other debris. A gully trap can have up to four waste pipes draining into it and should be raised above the ground to prevent stormwater from the roof or ground draining into it. House gully trap If rainwater can enter your gully traps they need to be fixed. It is the landowners responsibility to do this. Rainwater entering gully traps is a major cause of wastewater overflows during heavy rain. Contact Council for advice on how to inspect and fix your gully traps. Don t confuse your gully trap with a stormwater drain houses often have small drains around the outside and these lead directly to rivers and the sea. Remember all the water that washes off your roof, driveway or the street flows directly into streams or the harbour. Illegal gully trap allowing rainwater to enter SAVE THE DRAIN FOR RAIN Small stormwater drain (not to be confused with a gully trap) PREVENTING WASTEWATER OVERFLOWS 9

12 6. WASTEWATER OVERFLOWS - PROTECTING YOUR HEALTH Ko ngaa waipara he huarahi tuku hei tiaki to hauora Contact with wastewater can cause diarrhoea, and more serious diseases like cholera, typhoid, and dysentery. When Council is aware that an overflow has affected a waterway or the harbour, health warning signs will be put out in prominent locations, and the media is advised. If you see health warning signs or you think an overflow has occurred there are a few things you can do to minimise the health risk to you and your family: Do not swim, fish or gather shellfish if health warning signs are in place. Minimise skin contact with sewer water, especially if you have cuts and sores. Keep them clean and covered. Do not allow children or pets to play in areas contaminated by sewage overflows. Do not eat or drink anything exposed to the sewer water, including vegetables from your garden. Health warning sign put out following an overflow Keep contaminated objects, water and hands away from your mouth, eyes and nose. Wash hands immediately following contact with sewer water or contaminated objects or surfaces. Following heavy rain water may not be healthy due to contamination washed off the land. Contamination may come from industrial sites, roads, farms, etc. It is common for elevated bacterial levels to be recorded in waterways after heavy rain. Harbour waters may be unsafe after periods of heavy rain YOU ARE RECOMMENDED NOT TO SWIM IN THE HARBOUR FOR 48 HOURS AFTER HEAVY RAIN. 10 BEST PRACTICE GUIDELINES FOR STORMWATER POLLUTION PREVENTION

13 7. HOW YOU CAN PREVENT BLOCKAGES AND OVERFLOWS Pehea te whakakore purunga, maringi noa ranei o te wai Do not flush these! There are a few simple things you can do to prevent causing a blockage or overflow: Place a waste basket in your bathroom to dispose of solid and inorganic waste. Disposable nappies, condoms and personal hygiene products do not belong in the sewer system. These need to go into your domestic rubbish. Condoms Sanitary products Rubber gloves Medical wipes Collect fat, oils and grease in a container and dispose of it in the rubbish bin or bury it in the garden. Start a compost pile or worm farm for food scraps. Take inorganic rubbish to your local refuse station. Put baskets/strainers in sink drains to catch food scraps and other solids. Before you plant trees, check how big they are expected to grow and place them in a suitable area away from pipes. Ensure your gully trap is legal (contact Council to check this if you are unsure). Dental floss Disposable nappies If you didn t do it don t flush it Mena kare koe i tuku, kaua e tukuna These are some of the more interesting items that have caused blockages in sewer lines: An entire deep fryer Dead animals Doormats Wigs False teeth Large rocks Blocks of wood PREVENTING WASTEWATER OVERFLOWS 11

14 8. HOW COUNCIL RESPONDS TO BLOCKAGES AND OVERFLOWS He aha ngaa huarahi a te Kaunihera hei whai atu i ngaa purunga, maringi noa ranei o te wai Once a blockage or overflow has been reported to Council our contractors will come and assess the problem and find the quickest way to fix it. This may involve flushing a sewer line to clear a blockage, diverting wastewater, inspecting pipes using a camera and even digging up pipes to repair them. Council will investigate what caused the problem so we can prevent it from occurring again. If it s a blockage in the public pipes, we will fix it. If it s a blockage on your property, the expense and responsibility is your's and you will need to hire a plumber. If there has been an overflow to public areas or the stormwater system Council will clean up any mess and disinfect the area. This may involve using vacuum tankers (sucker trucks) to collect wastewater. If wastewater has flowed into waterways or the harbour it may not be possible to remove all of the contaminated water. Vacuum tanker removing contaminated water from a stormwater pipe Council will put up health warning signs if there is a possible health risk and advise the media and any affected parties. Council will take water samples to check water quality and as soon as it s safe will advise the public and remove the health warning signs. Water quality sampling following a sewer overflow IF YOU NOTICE A WASTEWATER OVERFLOW CALL COUNCIL IMMEDIATELY ON BEST PRACTICE GUIDELINES FOR STORMWATER POLLUTION PREVENTION

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