A guide to choosing a wastewater system - Biolytix
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Choose the right system for your property One important decision you will need to make when building or renovating outside of urban areas is how to manage your wastewater. Most rural properties in New Zealand do not have a Council sewer to connect to and all household wastewater needs to be treated and disposed within the property boundaries. Septic tanks, which do very little to treat the wastewater, are becoming less acceptable to regulators and society generally, and more advanced wastewater treatment options need to be considered. Choosing an advanced wastewater system can be a complex process for most consumers. Claims on company websites, brochures and quotes from companies can be confusing, misleading or unsubstantiated. To make an informed choice for your wastewater management, we recommend the following issues are considered. © Biolytix Limited 2017 01
1 What level of 1. Primary treatment may have more maintenance requirements. treatment do you Primary Treatment (i.e. septic tanks) provides minimal treatment Higher levels of treatment will of domestic wastewater which generally be at higher capital and need? is only suitable for ground soakage by trenches. Primary operating costs and maintenance complexity – so it is important to treated wastewater should not be understand what level of treatment disposed of using driplines. is necessary for your property and whether the manufacturer’s claims about treated effluent 2. Secondary treatment levels can be substantiated. In New Zealand there is the On-site Secondary Treatment is a Effluent Treatment National Testing significant reduction in organic Programme (OSET-NTP) which is and particulate contaminants the only independent trialling of and is the most common level of package wastewater treatment treatment offered by package plants in NZ. Further information treatment plants in New Zealand. about the OSET-NTP and test Secondary treated effluent is results for different package usually suitable for land disposal treatment plants can be found via driplines. at waternz.org.nz/OSET 3. Tertiary treatment It is important to note however the OSET-NTP trials do not take into Tertiary Treatment usually includes account otherkey issues such some level of disinfection or as odour, noise, price, reliability, nutrient removal. Tertiary treated size, maintenance requirements, effluent may be able to be customer satisfaction etc. disposed of closer to waterways than primary or secondary treatment. Some Councils have regions (e.g. around Lake Taupo and the Rotorua Lakes) where wastewater systems are required to remove a certain amount of nutrient. Tertiary treatment will usually be more expensive to install and operate than primary and secondary treatment, and There are three main levels of treatment typically offered for domestic wastewater. 02 03
2 What is the treatment 3 Some Councils will only allow certain types of package capacity? wastewater treatment plant, with the most common benchmark being whether the treatment plant has a performance certificate from the OSET-NTP trial (see above). Some Councils in New Zealand, such as the Bay of Plenty Regional Council, publish a list of treatment plants that meet their criteria for installation in their regions: boprc.govt.nz/environment/pollution-prevention- and-compliance/on-site-effluent-systems-oset/ approved-on-site-effluent-systems/ How much wastewater can It is important to ensure the capacity be processed each day by of your wastewater treatment plant the treatment plant you are comfortably exceeds the maximum considering? Most package volume of wastewater you are likely treatment plants claim to be able to to produce. process a maximum volume of up to between 1000 and 2000 litres per The following are typical levels of day. If you exceed the maximum use in many New Zealand homes: Is the system capacity of the treatment plant it may overload the process, • 1-3 bedroom house, 2 – 5 causing reduced treatment levels, occupants: 300 to 1100 litres odour or more maintenance costs. Manufacturers will likely void the per day • 4-6 bedroom house, 6 – 10 approved for use warranty if treatment capacity has been exceeded. occupants: 1000 litres to 2200 litres per day in your region? 04 05
4 How much does it cost Installed prices of secondary package treatment plants typically • Does the quote include electrical installation? If not then find out to purchase & install range from $12,000 + GST to what is involved and how much it $25,000 + GST, with difficult or is likely to cost. remote sites being potentially more • Be wary of systems that claim to a package wastewater expensive. We have noticed the perception of the final price paid is not require a pump or electricity. In most circumstances dripline system in NZ? often lost in the customer’s overall disposal will require a pump to building costs for the project. It is deliver the minimum operational best to obtain written quotes from pressure. suppliers and then check whether • Is the supply and installation you are comparing ‘apples with of the land disposal system apples’ when comparing quotes. included? Also check whether the quote includes burial or We suggest at least confirming the covering of the land disposal following when comparing quotes: system (which may be a Council requirement or an • Does the quote include GST? owner preference). This can • Does the quote include supply be a significant additional and installation? cost if excluded. We certainly • Does the quote include recommend dripline burial. drainage? (This is typically • Are there exclusions like site excluded from an initial quote clearing, removal of spoil, as it can be quite site-specific. unforeseen excavation costs, Look out for quotes that require burial of disposal area etc? separate greywater and blackwater drainage, as this can add significant additional cost). 06 07
5 How much does 6 Does it smell it cost to operate or make lots of a wastewater noise? system? Wastewater treatment plants have The initial capital cost is one issue Keep in mind a house in Auckland potential to create unpleasant but the long term operating costs connected to the Council sewer odours and noise – especially if are just as important. Try to get and producing 1,000 litres per day they are not operating properly. some confirmation of what the in wastewater will incur well over Most brochures will claim ‘no following annual costs will be: $1000 per year in wastewater odour’ but it is worth talking to charges. existing owners of treatment plants • Servicing costs (frequency and you are considering to get some the cost per visit) It would not be unreasonable to confirmation of whether the no • Electricity consumption (ask for budget a similar amount per year ‘odour claims’ are true. evidence, as some types for an onsite wastewater plant of treatment technology use (which should cover all operating The same applies for noise. The 20 to 30 times more electricity costs, including an allowance Australian New Zealand Standard than others) for occasional component 1546.3 recommends treatment • Sludge removal replacements). plant noise should be less than • Component failure and 40dB, but some treatment plants replacement. make a lot more noise. Ask the supplier to provide certification of compliance with this Standard recommendation. 08 09
7 How reliable and Product and installation quality are critical issues to ensure • Have the manufacturer and installer been in business for a reputable are satisfactory long term operation of sufficient length of time? your wastewater system. Both the • Do the installer and manufacturer installer and manufacturer should have satisfied customer the manufacturer be reputable, reliable and well organised companies. We suggest testimonials? • Are the installers ‘registered & installer? you check the following: drainlayers’? Both the tank and disposal field should be installed • Do the manufacturer and by a Registered Drainlayer. You installer carry adequate can check current registration insurances? status for New Zealand registered • Does the manufacturer or here: https://www2.pgdb.co.nz/ installer have any Quality PGDB/PublicRegister.aspx Assurance accreditations? • How punctual was the installer • Does the manufacturer have or manufacturer when making any independent review of their their site visit, sending a quote, technology available? responding to emails/phone • Is the wastewater treatment calls etc? This may give you technology developed in New some confidence in their ability Zealand for New Zealand to supply, install and service conditions or was it imported the system within the promised from overseas? timeframes. You don’t want an • Is the manufacturer or installer unnecessary delay to hold up able to provide you with quality other project works. documentation such as Owner Manuals, installer manuals, specifications etc 10 11
8 Wastewater 9 Councils and other regulators often do not allow the use of reports insinkerators in houses with onsite wastewater systems installed. However, many manufacturers claim their wastewater system is suitable for use with insinkerators. Use of an insinkerator at a house will significantly increase both the organic loading and the hydraulic loading, and we therefore recommend against one. Even if the wastewater system manufacturer claims their system is suitable for Installation of a wastewater system have an engineer in their company use with an insinkerator, there will will require a Building Consent able to provide a report as a likely be increased energy use, from your local council, and the part of their total price, or at a maintenance cost and sludge consent application will require an reduced rate. Often companies pump outs. Where possible, it engineer’s wastewater report on will request a deposit before this is better for a household with site-specific issues such as: report is provided. If you do get a an onsite wastewater system to manufacturer/installer to provide separately compost or bury their • the size and likely occupancy a wastewater report you should food scraps. of the house check their credentials: • the likely volume of wastewater generated each day • Are they sufficiently qualified and • the level of treatment required experienced (e.g. an engineer, • the options for package geologist or similar)? wastewater treatment plants • Are they approved by Council • the type of soils present and to author wastewater reports suitable loading rates for in the region? those soils • Are they sufficiently covered by • the size and location of the a Professional Indemnity disposal area. insurance policy? In-sink waste • Will they visit your property to In New Zealand, a wastewater assess soils and site conditions, disposal units report is likely to cost between and is this included in the cost? $500 and $2,000 + GST if it is • Will they provide a ‘Producer provided by an independent Statement’ after the installation engineer, however some manufacturers/installers may to allow you to get Council Completion Certification? (insinkerators) 12 13
10 What waste does an 11 How often does a onsite wastewater wastewater system system treat? need servicing? Most package wastewater systems The onus will be on you as the Servicing frequencies and costs • Ask your manufacturer/installer/ are designed to treat all domestic property owner to ensure only can vary significantly between service technician to confirm household wastewater originating biodegradable, non-toxic items manufacturers, service technicians service costs and frequencies from toilets, showers, hand basins, enter the wastewater treatment and in different parts of the country. • Ask to see a Service Contract and the laundry and the kitchen etc. plant. Your manufacturer will The Council will usually require Service check sheet so you can They are not normally designed probably have a list of what can a service contract to be in place understand what service is being to treat: and cannot be treated. Non- between the property owner and provided biodegradable or toxic items a service technician. The service • Ask how long a service technician • Stormwater or surface water entering the wastewater system technician could be a part of is typically onsite for a standard (e.g. rainwater tank overflows) will likely result in additional often the manufacturing company, service • Process waste (e.g. home significant maintenance costs. the installation company or a • Ask what the expected response hairdressing salons, home If there is likely to be anything third party provider. Servicing is time is in the event of an alarm or brew waste) unusual about your wastewater, something that is required at least other malfunction? • Commercial laundry or make sure you discuss this with the annually and sometimes 3 to 4 commercial food preparation manufacturer. times per year, depending on the • Swimming pool or spa pool type of technology. Cost of a service backwash. is usually in the range of $100 to $400 per service. 14 15
12 What size and 13 The size of the disposal area is a function of the local Council rules, weight are the the amount of treated wastewater being disposed of, the type of disposal and the type of soil at your tanks? property. The type of wastewater treatment plant you choose will generally not affect the size of the disposal area required. An average size house on poor soils will usually require around 300m2 of disposal area if using pressure compensating dripline disposal. Some wastewater systems require • The size, weight and quantity of a number of large and heavy tanks tanks required which need to be transported to • Whether any special machinery your property. The more big tanks will required to deliver or install required, the higher the freight and the tanks on your property and installation costs will be. Large, what the costs will be How much heavy tanks may also require • The total area required for the more expensive machinery to lift tanks to be installed and where and install them. Larger tanks will this will be on your property also take up more space on your property and require more spoil to • The total volume of soil that will need to be removed from site disposal area be removed from site. We therefore recommend you check: and whether the costs of removal are included in the quote. is required? 16 17
14 Does the waste- 15 Ask to see a warranty from the supplier. Parts should be covered water treatment for at least 2 years. Performance guarantees are rare because performance depends largely on plant need regular the quantity of wastewater being treated and whether any toxic desludging? compounds enter the treatment plant, both of which are outside the manufacturer’s control. All wastewater systems will need occasional solids removal. Solids in all types of wastewater treatment are consolidated and decomposed, but they do not disappear and will eventually need removal before accumulation begins to affect the treatment plant operation. Check with the manufacturer what the What are the expected frequency and costs of solids removal is. guarantees? 18 19
Thank you We hope these Guidelines Cooks Beach Plumbing Davies Plumbing & for Choosing a Wastewater & Drainage Drainlaying Ltd System have been useful, and Coromandel Nelson, Tasman we wish you every success for 07 866 3189 03 544 2101 your project. Thames Drainage Morgan Plumbing We’ve tried to cover off the Coromandel, Hauraki, Marlborough, Kaikoura most important and most East Auckland 03 578 0060 commonly asked questions. 07 868 7004 However, if there is other Foley Plumbers - Christchurch information you would like WH Kelly Ltd Canterbury to know about purchasing, Bay of Plenty 03 343 0763 installing or operating an on 07 543 5296 land domestic wastewater Kere Marshall Drainage treatment systems, then Opotiki Drainlayers Canterbury please contact us or any of Opotiki & Whakatane 0274 359 005 our approved installers at one 07 315 6367 of the addresses below. Peter Hansen Drainage Donaldson Plumbing Canterbury Gisborne 027 536 9331 Associated Wastewater 06 863 3688 Management Ltd Menzies Group Northland Lifestyle Plumbing & Timaru, South Canterbury 09 437 2712 Drainage 03 684 8440 Hawkes Bay Owen Bennett Drainage Ltd 06 836 5100 Foley Plumbers - Oamaru Northland & Kaipara Oamaru 021 203 3808 Turfrey 0800 303 530 Hawkes Bay Laser Plumbing Warkworth 0800 182 182 All Septic & Drainage Ltd Rodney & Kaipara Otago - Dunedin 09 422 9051 Laser Plumbing Wairarapa 03 489 4828 Wairarapa, Masterton Water FX Limited 06 370 2259 Optum Plumbing & West Auckland, Rodney Energy Solutions 09 412 6322 Clark Plumbing & Queenstown Lakes, Gas Ltd Central Otago WB Civil Limited Whanganui, Taranaki, 03 443 5718 West Auckland, Kaipara Manawatu, Ruapehu 027 273 2311 06 343 8953 Laser Plumbing Invercargill Plumbcraft Turfrey Southland South & East Auckland Manawatu 027 530 4199 09 2967070 0800 182 182 Tomasi Plumbing & Drainage Systems Ltd Mana Plumbing Drainlaying South Auckland, Waikato Wellington, Kapiti West Coast 07 850 4370 04 233 8350 03 736 9715 Biolytix Limited biolytix.co.nz info@biolytix.co.nz 20 0800 700 818
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