On-Site Detention Tanks

OSD Tank

Looking to store rainwater runoff during times of heavy rainfall, to maximise your water capacity. Depending on where you are located it may require the installation of an on-site detention tank/s. The purpose of the installing the tank is not only to conserve water, it also supports urban development and protect the community, by bringing about a reduction in the number of floods to the local area.

What is an On-Site Detention Tank (OSD)?

Also referred to as on-site stormwater detention tank, an OSD is the system of detaining storm water and slowing discharging it to the council storm water system or to the drainage, by providing an on-site temporary storage. It is important to pay particular attention to the fact that an on-site detention tank only slows down the flow rate and it should not retain the water for use in other purposes. The tank that collects water for use domestically is called a retention tank or a rainwater tank.
An on-site detention tank should be always empty, except when it rains and for a short period after the rain has stopped. 

Why are On-Site Detention Tanks required?

Storm water detention tanks are required to be installed by your local council to prevent the existing drainage infrastructure, from getting pressured by the run off and ensure that the run off does not cause flooding downstream of your development. Changes in land use for urban development, building new roofs, site drainage and other hard surfaces increase not only the volume, but also the speed of storm water run-off. These factors also reduce the storm water capacity to soak into the ground.

This has made the different councils, to take immediate measures into consideration in order to prevent serious problems from happening in the future:

What are the Design Requirements of OSDs?

on site detention tank

The design of on-site detention tanks should be done, by a qualified engineer for approval by your local council. The system should include an OSD tank and a DC), which is the storm water specification Development Control Plan. The system should be complete with orifice plates, trash screens, inlets and overflows in the right position. If you want to save on cost, you can combine the OSD tank, with the rainwater tank in the design. The OSD and the DCP will be craned into position by our delivery truck. Rain Cycle provides clear instructions to make sure that your storm water detention tank is properly installed, once it is received on site.

The OSD system must have the capacity to store the runoff, caused by a rain event of up to 100 years. It must also be able to control the rate of water release, to make sure that the storm water system is able to handle the extra run off. So, once you have your approved requirements from your council on the installation of a storm water detention tank, then you can organise your design to meet the strict council requirements. 

You will also need verification that your system has been designed, to meet the calculated PSD and SSR and certified by a civil engineer. PSD is Permissible Site Discharge, which is the maximum rate of discharge that the storm water system can handle. SSR is Site Storage Requirement, which is the minimum storage volume required to store temporarily and offset the excess water run-off.

The on-site storm water detention system requirements differ from one council to another, so it’s important that you have it discussed, with your local council, before you start implementing any storm water detention solution. 

Obtaining advice from the experts like Rain Cycle about detention tanks design and installation will ensure you meet the necessary requirements and approvals. Rain Cycle is in the business of design, construction, and installation of water tanks of all sizes. We supply concrete water tanks intended to be buried deep underground, such as under garage structures. We prefabricate our products right here in Australia, so you know you are buying Australian made. We can also build on site according to your specifications. Our workforce consists of skilled, professional and licensed water tank specialists.

Rain Cycle tanks are purpose-built, durable, and reliable, they can last for decades. Call us if you need to install a detention or retention tank on your property. We will be happy to help work with you on this project from design, council approvals, manufacture, and installation. We also provide full service and warranty back up, so we can help take the stress and worry out of the whole process for you.

What properties need OSDs?

Detention tanks, usually, are specified by the council, in regions or parts of the town where there is a potential risk of flooding. With the current increase in housing and the challenges that go with it, the storm water systems provided by the council are to a large extent, undersized. So, in most cases, if your intention is to build a new home or renovate and extend the home, where storm water systems are yet to be renewed, it is most likely that you need to install a detention tank.

OSDs or on-site detention tanks are required on all industrial, commercial and special use buildings, such as recreation halls, schools and community buildings. Other properties such as townhouses, home units, villas, dual occupancy lots and sporting facilities, such as basketball and tennis courts are also required to install on-site storm water detention tanks.

However, if you plan on building a solo residential house or you are renovating an existing structure and maintain the drainage system currently in operation, you may be exempted from the council requirement, this is an requirement you should check with your local council. The same also applies, if your total property area is below 250 square meters or your site you are going to develop on is, in the bottom sector of the catchment. 

Operation of On-Site Detention Tanks

By capturing and temporarily storing storm water run-off, detention tanks slowly release the water, through a small opening into the council’s stormwater drainage system. This process of detaining and slow release of water lessens the peak flows whenever there is a rainfall, thereby lessening the impact on underground water infrastructures in the local areas, especially those prone to flooding.

The flow of storm water from the roof and other hard surfaces is thereby controlled by the OSD tanks. If your building roof has a large surface area, it can capture a large volume of storm water. If the water flows freely, it is highly likely that the storm water drainage system of your local council would be overwhelmed. On-site detention tanks detain the water and then release it in a controlled manner, to prevent surges of storm water.

How much will it cost?

Our pricing can be tailored for your individual projects based on your needs and budget .
Costs can vary depending on the size, accessories, finish and strength of the tank, so call the team at Raincycle for more information.

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