Residential Wastewater Systems

Transcription

1 Residential Wastewater Systems An introduction to installing and maintaining a domestic septic tank.

2 What is this booklet about? Home wastewater systems are used on properties that are not connected to Council s sewer. In the Gisborne district it s all areas outside Gisborne city, Te Karaka, and Te uia townships. It includes Wainui beach, akaraka, and rural and coastal areas. When it works well, managing your own waste is as easy as collecting your own rain water, but if something goes wrong, it can be unpleasant and expensive to fix. This booklet is for people who use or need to install an onsite wastewater system commonly referred to as a septic tank and will help you get it right from the start. age 1 Resdiential Wastewater Systems (Jun 2015) - A574901

3 Contents Onsite wastewater systems 3 Types of systems 3 How the system works 4 Installing an onsite wastewater system 5 Wastewater treatment professionals 6 Legislation and resource consent 6 xempt work 6 Looking after your system 6 If things go wrong 7 Costs 7 Find a wastewater specialist 8 Approved site assessors/system designers 8 Tank cleaning specialists 9 aintenance and service agents 9 Residential Wastewater Systems (Jun 2015) - A age 2

4 Onsite Wastewater Systems Onsite wastewater systems are used to dispose of all household waste that goes down the drains or toilet. With an onsite wastewater system, there is no flush and forget all your liquid household waste has to be safely and hygienically processed on your property, in your wastewater system, which itself is a living system. An effective system contains and processes waste without contaminating ground water or surface water, or having adverse affects on the environment. Types of systems There are two main types of onsite wastewater systems: one or more septic tanks with a gravity or pumped effluent disposal bed a home treatment system that usually has dripper line disposal. Your wastewater system may include: sanitary plumbing fixtures connected to drain pipes that take sewage and sullage that s the liquid from kitchens, wash basins, toilets and laundries to the septic tank treatment tanks passive, aerated or filtered a distribution system, pump, siphon, or gravity fed an effluent disposal system, trenches, beds, mounds, or dripper lines. age 3 Resdiential Wastewater Systems (Jun 2015) - A574901

5 How the system works The type of system you install will depend on your property. ost systems work in a similar way in that wastewater is gradually separated, treated, and dispersed with the help of an army of natural organisms. Just as we have good bugs in our stomachs, septic tanks have anaerobic bacteria that partially breaks down solid waste. Your septic tank depends on these organisms to work properly, which is why you must keep your septic tank a chemical free zone. Disposing of any kind of chemicals paint, disinfectant, petrol, flammable liquid, bleaches down your drains or toilets can wipe out the organisms your tank needs to work properly. When you flush the toilet or run the tap, sewage and sullage flow to the septic tank where the solid matter settles on the bottom and forms sludge, while fats and lighter matter float to the surface to form a scum. Figure 1 - Conventional Septic Tank Filter if required Inspection Cover - must be above ground level All household waste waters (excluding rainwater) To land application trenches or bed Scum Zone Settling Zone Sludge Zone The intermediate liquid that has had most of the organic matter digested by your tank s bugs is eventually discharged into an effluent trench a series of underground pipes on a gravel bed used to evenly dispose of treated wastewater. While it soaks away it is further treated by organisms that live in the drainage metal and soil. Residential Wastewater Systems (Jun 2015) - A age 4

6 Figure 2 - Septic Tank and ffluent Trenches Septic Tank ump Chamber (if required) Approved ffluent etal Distribution Box ffluent Trench Unexcavated The effluent trench is dug deep enough for treated wastewater to safely soak into the ground without contaminating the groundwater. The trench is lined with clean washed river metal, with the pipe laid flat with more river metal. A textile filter cloth is laid over the metal before backfilling to prevent the downward movement of soil that could clog the drainage metal. The top of the trench system must be crowned to stop rainwater pooling. Figure 3 - Conventional Trench System Crowned Finished Surface xisting Surface Topsoil Filter Cloth erforated ipe Distribution Aggregate (20-70 mm) 600mm 75mm min 100mm Installing an onsite wastewater system If you re installing a new system, it s important that the tanks and effluent beds are the right size so they have the time and area to work efficiently. Talk to a professional about the best type of system, and the best size and location, for your property. age 5 Resdiential Wastewater Systems (Jun 2015) - A574901

7 WASTWATR TRATNT ROFSSIONALS The Council maintains a list of approved people who do site assessments and design for onsite wastewater systems in the Gisborne district. They can evaluate the soil type and soak rate, and use a set of guidelines to design a system that will suit the building and the property, and protect the surrounding environment. In general, installing a septic tank or effluent disposal system will require some degree of site evaluation and design before a building consent can be issued. You will need to provide details of this work, such as a site plan and details of the system type, size and layout, with your building consent application. The Council will only accept it if it has been done by one of the assessors listed at the back of this booklet, or a recognised wastewater engineer. Legislation and resource consent Onsite wastewater systems must meet the environmental standards in the Resource anagement Act and the Gisborne Regional Discharges lan. They must also meet the functional and durability requirements of the New Zealand Building Code and the Building Act. To install a new system or replace a failed system you ll need a site assessment and building consent. The site assessment is to be carried out by an approved assessor, who will design a system or identify the work required to rectify the failure. Or you can use a recognised wastewater engineer to design a system. The design must be based on the site assessment. XT WORK Some like-for-like building maintenance projects don t need a building consent under exemptions in Schedule 1 of the Building Act. Although replacing a failed effluent line is included in the examples in the schedule, it is likely to still need a building consent. A failed system won t comply with the regional rules under the Discharges lan and therefore the like-for-like option does not apply. Looking after your system These tips will help to keep your septic tank working safely and reliably. Desludge every three to five years or when scum and sludge take up two thirds of the tank or the first stage of a two-stage system rotect your tank and effluent lines from vehicles If you have a grease trap have it cleaned out regularly Keep the vent and/or access cover of the septic tank exposed If you have an outlet filter have it inspected and cleaned. Residential Wastewater Systems (Jun 2015) - A age 6

8 roblems can arise when systems aren t maintained and when absorption areas get blocked or clogged. Look out for: wet or soggy absorption field with wastewater ponding on the ground a bad smell near the septic tank or absorption area drains and toilets run slowly grease trap is full or blocked. If things go wrong A failed onsite wastewater system is a serious health and environmental hazard and can lead to: the spread of infectious disease an increase in mosquitoes, flies and rodents pollution of waterways, beaches, streams and shellfish beds contamination of bores, wells and groundwater alteration of local ecology air pollution and odours. Regularly cleaning and maintaining your system will help to prevent costly failures. Costs It can cost between $15,000 for a small basic septic tank system to around $22,000 or more for a more complex system (2014 costs). Transport costs to remote sites could add significantly to these costs. The cost of cleaning your tank can also vary depending on where you live. This is because contractors charge for mileage to and from your property. Systems that have been installed since 2002 may have a filter on the outlet from the second tank or chamber. These must be cleaned regularly or the filter will clog and cause backups in the tank. Systems with a pump, aerated home treatment plants (AWTS), and low pressure dosed effluent systems have ongoing power costs. An AWTS needs bi-annual maintenance. All maintenance is at the homeowner s cost. For comparison, all single residential properties in Gisborne city that are connected to the main sewer line pay about $560 a year. This is on top of the original connection costs, which depend on the distance between the house and the main sewer line. Over the life of your septic tank, reticulated and tank costs are comparable. age 7 Resdiential Wastewater Systems (Jun 2015) - A574901

9 Find a wastewater specialist AROVD SIT ASSSSORS/SYST DSIGNRS Andrew Appleby or George Winkler LD O Box 671, Gisborne Gary Thompson Thompson Drainage 81 Innes street, Gisborne John Taylor Terry Taylor Drainage 89 Customhouse Street, Gisborne Ian Donaldson Donaldson lumbing 73 Carnarvon Street, Gisborne Alan Hall 8 Ferry Road RD 1, Gisborne Carl Horne 834 Gladstone Road, Gisborne Sarah illar vironmental ngineer Opus International Consultants Ltd F F F W (06) (06) info@lde.co.nz (06) thompsondrainage@xtra.co.nz (06) (06) terrytaylor@xtra.co.nz (06) idonaldson@vodafone.co.nz (06) (06) (06) carlandtech@xtra.co.nz (06) Sarah.illar@opus.co.nz The use of any firms or people listed in this booklet is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the Gisborne District Council of any product or service, that they provide or to the exclusion of others that may be suitable. You may use your assessment to get quotes from a number of drain layers and are in no way obliged to use the drain layer who carried out the assessment. Residential Wastewater Systems (Jun 2015) - A age 8

10 TANK CLANING SCIALISTS Below are some local service agents who offer septic tank cleaning in Gisborne. Regularly cleaning your tank will help to keep your system working well. Agent Contact details Wayne s Waste (06) Terry Taylor Drainage (06) Baywaste/nvirowaste (06) orris ataira Septic Solutions Ltd (06) (Ruatoria) (06) ( Te Araroa) Fulton Hogan (06) AINTNANC AND SRVIC AGNTS There are several companies and agents in Gisborne that offer tank maintenance services. Type of wastewater system Recommended servicing frequency Agent contacts Bio-Cycle Oasis Clearwater Gary Hills (06) thewatertankman.co.nz Bio-Cycle Thompson Drainage (06) thompson.drainage@xtra.co.nz General servicing Brian Rofe lumbing (06) brofe@xtra.co.nz KiwiTreat KiwiTreat Limited (Rangiora) (03) Biolytix Aquablue Devan Blue Annually Donaldson lumbing Limited (06) idonaldson@vodafone.co.nz age 9 Resdiential Wastewater Systems (Jun 2015) - A574901

11 Type of wastewater system Recommended servicing frequency Agent contacts HYNDS Lifestyle Terry Taylor lumbing Ltd (06) Carl Horne Innoflow - Advantex Annually Walters lumbing (06) waltersplumbing@xtra.co.nz AirTech 9000 Steve Wolters lumbing (06) nviroflow Ross Brown Gould Tanks Contact Council for advice (06) Septech Turbo Jet 2000 Annually Watercycle Annually Find out more For further information on domestic wastewater systems see Your Septic System a comprehensive guide for owners and users. You can download it from our website or pick up a copy from customer services. Residential Wastewater Systems (Jun 2015) - A age 10

12 15 Fitzherbert Street, Gisborne phone web facebook GisborneDc