All posts by Drainage NZ

New Manhole Connections For Subdivisions

If you are tasked with the drainage in a subdivision, then one of the many drainage tasks will be the installation of new manholes or creating new connections to existing manholes.  The rules and regulations regarding the installation of new manholes will differ from region to region and so if you have FIFO’d (Fly in Fly Out) or are on a job outside of your normal regional council, it will pay to check what the local council regulations are and be familiar with them before embarking on your project.

For small to medium sized developments, new manholes are usually required on Council pipes where a new connection is the same size pipe as the existing pipeline it is connecting to. As well as this, new manholes can also be required if there is a change in the horizontal direction or grade in the pipe, if there are poor ground conditions which hinder the construction of ramped connections difficult (this can be assessed by engaging a Geotechnician as a geotechnical report will be required), if your 150mm diameter pipe serves more than 2 properties or is at the end of 150mm diameter pipe that is further than 50 metres from the next manhole.

Often when preparing to submit quotes for new manholes the following items can be classed as exclusions:

  • Soil Removal (To be spread on site)
  • Any finishing works
  • Removal of spoil
  • Hard-rock breaking
  • Building Works
  • Traffic Control
  • Subsoil or Retaining Wall Drainage
  • Concrete and Landscaping reinstatement works
  • CAD Drawings (Hand drawn to be provided on site)
  • All excavation limited to 800mm unless stated otherwise
  • Removal of existing services (Tanks, pipework, manholes etc.)
  • Limited to filling of trenches to 200mm above drainage, does not include any finishing works such as concreting, trench fill to required levels.

However, this list is not a full and final, and depending on the job site it may be pertinent to include some of the above in order to offer full service for your clients.

If you are working within the confines of the Auckland Supercity and you need to extend or modify the public water and/or wastewater networks, you will need to gain approval from both Auckland Council and Watercare before any work starts. Outside of Auckland the approval will need to be gained from the local borough or city council and the relevant waste water service.

The usual process for obtaining consent before embarking on the drainage works will be for you to apply and obtain resource consent from the council and then apply to the waste water service for a network extension. Some councils will allow you to apply directly to them for an engineering plan approval after obtaining the resource consent.

Before submitting any applications, it is wise to consult with a civil engineer to discuss your requirements and to ensure that all extensions or modifications to the water or wastewater network comply to the local waste water services engineering standards.

When planning the positioning of the manhole connections keep in mind that where you deem a suitable location for the manholes may influence your pipe alignment.

Generally, there is a minimum clearance required of 1.0m from the outside diameter of the manhole riser to any structures or boundaries which needs to be provided to facilitate maintenance and rescue. The local council may determine other specific requirements subject to the individual site characteristics.

The placement of the manholes needs to be with the view of minimising any interference with future building.

The structure of manholes has been engineered and developed over the years and there are many rules and regulations as to the designs acceptable for implementation.

All manholes in New Zealand need to be designed to support all existing and any predicted future dead loads. Design live loads for reinforced concrete manholes and cast iron covers shall be HN-HO-72 for motorways and arterial roads, HN for local streets and driveways, and 20kN wheel load for non-trafficable areas.

Manholes are required to be able to support lateral earth pressure, hydrostatic pressure and any expected high eccentric lateral pressure due to live load or surcharge load. You will also need to consider the manhole foundations which need a design that accommodates the bearing pressure and at no time exceeds the safe bearing capacity of the soil.

Reinforced concrete pipes produced to AS/NZS 4058:2007 can be used as manhole risers provided that the load class of the pipes is adequate to carry the service loads on the manhole. Use of pipes with oval reinforcement is not acceptable at any time or at any site.

Most Manhole work (unless classified private) is considered as Public work. In Auckland drain layers must be Auckland city and Watercare registered to be allowed to work on public systems. Both of which Drainage NZ are. We carry all the required certifications and qualifications to accommodate and size public work. Drainage NZ can assist you in the design, application and consenting stages including manhole installations and involved drainage.

New Home Residential Drainage

Building a new home, whether it is a one off or part of a large scale development, is stressful. Don’t listen to anyone who tries to convince you otherwise.

One thing that Drainage NZ can help you with is your… Drainage! We have a great team who are well qualified and used to liaising with builders, architects, engineers and councils. We can create the best solution for your site and come up with specified custom designs to suit. We can arrange and organise building consents for your job to help take that stress away.

Drainage NZ can project manage your drainage requirements. With over 20 years of experience in the field, our drain layers are exceptional at what they do. They are all New Zealand certified and registered drain layers and you can be assured that your job will be completed to the highest standard and will comply with all NZBC standards.

Our Quantity Surveyors are out on sites daily, pricing jobs and they can bring their expertise to your site too. We are determined and focused on meeting your deadlines. This means that you can relax knowing that we are working hard on your site to keep your build on schedule.

When looking for a drainage company you can’t go past Drainage NZ as we have all our own equipment. This means that our costs are lower than other drainage contractors. Our equipment is well maintained and our staff are familiar with our equipment. This means that unlike some of the other companies who have to rely on hired equipment we are less likely to have issues with our equipment.

We always locate all existing services before undertaking any drainage or drilling work. We locate and mark existing: Power, Gas. Water, Drainage, Telecom and Power lines.

Drainage NZ are serious about health and safety. Our priority is to protect public and employees during all drainage works. This includes Fencing, Notices and warning signs, protection from falling objects, a requirement to use protective helmets, goggles and hearing protection when applicable.

All employees are trained and required to comply with our relevant health and safety policies. Drain layers are trained in confined spaces, methods of excavation, shoring and are site safe registered.

So if you are needing to find a company that you can trust with your residential drainage installation and has the expertise, the equipment and the best price give Drainage NZ a call today on 0800 372 465.

Thrusting, directional drilling, water main leak repairs and replacement

Yes we do it All!

Drainage NZ are setup to replace and repair waters at unbeatable rates! Thrusting and directional drilling services also available.

With the Pohutukawa’s bursting into full flower this past week we know that Summer for 2016/17 has definitely arrived. Don’t be persuaded to think otherwise with the intermittent rain that seems to keep surprising us – all the weather watchers are saying we’re in for a long, hot drawn out summer.

With the dry season upon us, the ground we stand on, build on and otherwise exist on is going to dry out. When the ground dries out the natural consequence is that the ground contracts. When this happens, water mains can burst under the pressure.

A burst in your water mains supply between the street and your meter is the responsibility of the water supply company; but the pipe between the meter and your house is your responsibility.

There are three types of water mains commonly found in New Zealand. Galvanised, Copper and Plastic.

If you have a galvanised water main, this pipe is likely from the 1920’s. Simply due to age these pipes are usually very corroded internally and it is uneconomical to repair these. Replacement is your only option.

If you have a copper water main these are usually easy to locate and able to repaired fairly well without incurring large costs.

If you have a plastic water main, then a number of issues are usually found with these. A lot of early plastic water mains were made from a very hard polyethelene. Polyethelene is susceptible to pin holing or splitting.  This needs to be completely replaced.

Once a pipe is over 30 years old, it will probably leak again

Drainage NZ are setup to replace and repair water mains at unbeatable rates!

Drainlayer $ 75 + GST / HOUR
Truck and Driver $ 90 + GST / HOUR
Drainlayer and Excavator $ 110 + GST / HOUR
Drainlayer Labourer $ 45 + GST / HOUR
Concrete cutting $ 45 / METER

Soil Removal based on local fees

Drainage Fix Pricing:

100mm UPVC FROM $ 55 / meter
100MM SN16 (heavy duty) FROM $ 65 / meter

Drainage NZ also have thrusting and directional drilling services available. Thrusting is used when installing:

  • Water Distribution Piping
  • Fire Protection Lines
  • Sanitary Sewer Piping
  • Storm Sewer Drainage Piping
  • Gas Distribution Piping
  • Landfill Applications
  • Irrigation Applications
  • Electrical/Telecommunications

Using the latest technologies and techniques, we also provide directional drilling. We service jobs big or small for both residential and commercial at competitive rates; telecom and water mains, storm water drains and sewers.

Directional Drilling allows for

  • Less traffic disruption
  • Lower cost (no labour, concrete reinstating etc)
  • Deeper installation possible
  • Long installations possible
  • Quickly completed
  • Safer for the environment

So watch out this summer for any burst mains and if this happens at your home or workplace – keep Drainage NZ in mind. If you have drainage needs right now – give us a call on 0800 DRAINLAYER (0800 372 465) and see what we can do for you!

Our Drainlayers specialise in public drainage

Public drainage includes all works that take place on public stormwater or sewer lines. This will includes repair works and new installations.

In Auckland, city council is responsible for stormwater while Watercare looks after the public sewer network system.

Whether a drainlayer is working on the public stormwater or sewer line, applications to both authorities must be made and approvals obtained before any works may take place.

Some councils such as Manukau city council may also have their set of standards which may defer to the common Auckland city standard. One example of this is the well-known “London junction” which is an approved standard in Manukau.

Whilst a registered drainlayer may do any residential drainage works, special training, experience and registration with Auckland city council and Watercare is required to enable works on the public network.

Drainage NZ have obtained all qualifications and experience to repair or install any size public drainage. Scope of experience and works include:

  • Public sewer line thrusting over 200mm.
  • Road drainage and manhole installation. Up to 1500mm diameter.
  • Sub divisions and rearranging of network layout.
  • Public sewage pumped systems.
  • Public stormwater and grease management.
  • Commercial grade Grease traps.
  • Repair works on large scale public systems.
  • Design and planning of public networks. 

Drainage NZ are able to advise on solutions and provide quotes in a timely manner on any size public drainage work.

Give us a call on 0800 DRAINLAYER for more information.

Here are some images from a recent job on the Northshore showing extensive repair works to existing public manholes. Works included raising levels to accommodate a subdivision and raising of existing ground levels.  

manhole_installation manhole_benching  manhole_repairs  public_drainlayers  9 8-2

NZ’s Wet Season has begun

Is your basement, garage, underground flat and / or storage area ready for the upcoming wet season by being protected against flooding?

Spring has started with a wet bang in New Zealand, especially in Auckland. In 2017 an additional 5% (L/sqm) in rain fall is expected when compared with 2016 stats. Storms are more frequent, heavy and short resulting in “flash floods”.

How does the ground respond to flash floods and what solutions are available?

The earth’s condition prior to rainfall is very important to determine the outcome when a flash storm hits. Has it been raining slowly for a few days prior or was the ground dry?

For example in Auckland many suburbs have been developed on clay (predominantly West Auckland and Northern areas) and still don’t have access to the public storm water system. Such properties rely on the stormwater management system within the boundary which is often in form of a soakhole or if lucky a curb discharge.

Unlike areas such as Mt Wellington or Onehunga that have access to underground volcanic cavities, or the public system, homes that manage their own stormwater rely on soil percolation. In simple terms “how quick can my ground soak the water?” The higher the rate, the higher the soakage reducing risk of flooding.

Lower percolation values are common and when they apply, alternative methods need to be used to manage stormwater. If nothing is done, a high level of surface water will result in flooding and over a longer period of time the ground will be charged with so much water it will expanding to a point where underground streams may result finding the least path of resistance into your basement area if no protection is available.

Site conditions such as the following play a critical role:

  • Level of elevation
  • Ground type
  •  Percolation values (soakage tests can be done)
  • Depth of areas affected
  • Current stormwater management system

In the following pictures (Birkenhead Auckland) you can see some of the processes we use to tackle ground water (not in order of works). Are you affected? Call us for a ground water solution.

digging_for_subsoiltrench_shoring

nova_coil_subsoilgeotech_filterationsubsoil_drainage_basement

approved_drainage_fill

Auckland city council is pushing for more detention tanks

So for starters, what is a retention or a detention tank?

Here is a clear definition from Auckland city council.

Detention tank: Detention tanks work by temporarily storing stormwater runoff during a rainfall event and then slowly releases the water into the public stormwater system. These can be located either above or below ground.

Retention tank (Water Harvesting) : A retention tank is used to permanently hold rainwater, which can then be reused for hose taps, toilet use and laundry purposes. Also known as a single purpose rain tank.

Dual purpose tank: Dual purpose tank both retain and detain rainwater. The bottom third of the tank is used to store rainwater permanently (retains) for non-drinking water supply and the upper two thirds of the tank temporarily holds (detains) rainwater and slowly releases it until it reaches the retaining level.

Water supply rain tank: These tanks store rainwater collected from roof areas and provide the main water supply to a household, this includes drinking water. This practice note does not address potable water supply requirements; for further information refer to Clause G12 of the NZ Building Code, which can be found at www.mbie.govt.nz.

Why are detention tanks desired by Auckland city council?

Auckland is growing! As such, its infrastructure must also grow to keep up with the demand, this includes its public sewer and storm water systems into which all properties discharge. Keeping up with this growth could cost tax payers Billions of dollars.

1000’s of new homes are being built with even more homes being extended adding hundreds of thousands of square meters of roof surface collecting additional rain water.

All this water needs to somehow be managed , if not, our public storm water systems will get overwhelmed affecting our public sewer lines and that is something no one wants for obvious reasons. So Auckland city council have come up with a solution that will slow down this infrastructure growth.

The solution was to simply make the managing of this additional rainwater the homeowners problem by introducing detention tanks. The surface area of the roof will determine the size of the detention tank. Rule of thumb is that 1 square meter or roof surface area will equal to 100 liters of detained water (this can change depending on council or conditions).

Detention tanks are designed to take the first load of rain, then with a controlled outlet slowly release the water back into the public storm water system. The size of the controlled outlet will be specified in your consent application.

The controlled discharge will allow the public storm water system to cope with the initial downpour, at some point the tank may completely fill up because the controlled outlet may not keep up with ongoing downpour. At this point in time the tanks will automatically overflow directly into public system. In theory, this should only happen every 100 years :).

In the images below you can see underground detention tanks have been installed (no pump). Having them underground is a great way to hide them. These specific models are very handy because they are only 1 meter deep allowing us in most cases to find a gravity solution rather than having to use a pump.

Drainage NZ can advise on many variations of retention and detention setups. This includes commercial and residential solutions. Simply give us a call if you have any questions.

My next article will discuss a maintenance schedule council urges home owners should maintain.

underground_retention_tanks
retention_chamber_overflowunder_ground_5000L retention_tanks_and_chamberoverflow_relief_gully

Drain Unblockers or CCTV Experts?

blocked_toiletA blocked drain is the last the last thing you would expect when you are relaxing on the weekend. Suddenly your kitchen sink is not draining, your gully trap is overflowing or even worse your toilet decides to throw up!

This is exactly what happened to Sandy in Remuera Auckland over the long Anzac weekend.

After several calls to several drain unblockers Sandy quickly got confused about what service was required, the cost for that service and whether or not it would solve the issues right away. After 1 hour of talking to multiple drain unblocking service providers, Sandy just about gave up and was more confused than to begin with.

Thankfully she came across Drainage NZ!

After only 15 minutes on the phone with Sandy, we identified the issue by asking a series of simple questions. Experience allows us to ask the right questions, go through a simple process of elimination and pin point the problem and quote the correct cost.

Many companies are understaffed and unwilling to service a “simple” drain unblock at a “simple” cost. Like in Sandy’s they company in question would not come to site unless also  CCTV was booked. Having asked the right questions it was quickly determined that the issue was inside the building envelope and not outside.

After arriving onsite, the problem was resolved with a simple plunge! 3 year old Marty put her teddy down the drain causing the blockage. We were able to get our drain unblocking snake down the toilet and pull the offending Winnie the pooh out hence resolving the issue. You can imagine Sand’s relief!

The cost? A simple minimum weekend charge out rate.
Drainage NZ are available 24/7, call 0800 DRAINLAYER for more information or free quotes.

Stormwater Drainage, Why So Crucial

stormwater_draiange_why_so_crucial

Has your property developed a new swimming pool after that last storm or heavy downpour? I wouldn’t try swimming in it though, floodwaters are usually filled with contaminants and pollution from the water picking up things such as trash, oil, fertilisers and what ever else it has swept over before gathering into your new pool.  Just imagine what could be floating around in there contaminating your home and waterways. This is why proper stormwater drainage is crucial to keeping your home and your surrounding environment safe.  If not installed properly it can also become home to mosquitos who will use this wonderful water source as a breeding ground, which is no fun unless you’re a fan of these little bloodsuckers.  A properly installed stormwater drainage system will be strategically placed to ensure your home is drained properly, so you will no longer have unwelcome “swimming pools” coming up on your property every time it rains.

Not having a stormwater drain or having an improper stormwater drainage system that is not operating properly can also cause damage to your house. Water pooling around the base of your house can weaken the structure and shift soil causing cracks in walls and foundations. The shifting foundation can stop doors and windows from sealing properly causing home dampness and mould. We all know a damp house will cause a host of physical illnesses such as respiratory problems. Also you have the cost of running a dehumidifier to try dry your home, heaters to try keep your home warm, the list goes on. So for your health, safety, and your bank account having a stormwater drain installed properly is a must.

In Auckland,  drain layers are required to have additional certifications to work on stormwater systems. Drainage NZ has these certifications along with 20 years experience. Our work is guaranteed. So call us now, we will take care of everything with one call so you don’t have to call around companies for different reasons and for different equipment for different jobs and areas.

Blocked Drains? You Might Need A Repair

Blocked_drains_repairMore often than not, a blocked drain is a simple solution which involves quick unblocking of the drain from debris that got stuck in out. However, sometimes can also be much more complicated.

A CCTV inspection of the drain will quickly reveal if there is damage to the drainage causing the blockage. Damage can be caused by a number of things including tree roots growing into the pipe, damage caused by humans, age, or other external forces.

Should you find your drains damaged, quick repair is crucial. Many times it is possible to repair the drain by doing a relining, without the need for excavation, which is the ideal scenario. In extreme cases, the drain may need to be completely excavated and replaced with new pipes, but this is a rare occurrence.

Drainage NZ can help you with all your drain repair needs. Give us a call on 0800 372 465 today!