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Types of drainage - pros & cons (with independent cost comparison)

types of drainage

There are two main approaches to surface water drainage:

  1. Linear drainage
    Simple one-way falls are required for linear drainage, enabling a continuous line of water capture which quickly and efficiently collects and transfers surface water off site.
  2. Grated pit and pipe drainage
    Precise and exact grading is required to intercept surface water with the grated pit and pipe option. The pits are located at strategic areas on the pavement to collect the water which is removed from the site via a network of underground pipes.

Modular, factory produced trench drains offer consistent quality and can be created with advanced shape profiles with a built-in slope, providing additional benefits and cost savings.

Modular Precast Trench Drains

A cast-in-situ drain is created on-site during a concrete pour. It has some similarities with modular trench drains except for the following disadvantages:

Cast Insitu Trench Drain

A spoon drain is a formed swale in the pavement, often leading to a grated pit.

Spoon Drain

Point drainage consists of a series of grated pits located at strategic places in the pavement. Precise and exact grading is needed for efficient drainage.

Point Drainage

Independent investigation

A report was prepared by an independent quantity surveyor, Rider Levett Bucknall, to compare the installation costs of three alternative surface drainage methods for the carpark of the Aquatic Centre at Homebush, NSW.

The methods under investigation were

  • Grated pit & pipe system – point drainage (Figure 1.) or
  • Grated trench drains (Figure 2.), which can be further categorised into:
    a. Cast in-situ trench drains
    b. Precast modular trench drains (ACO Drain®)

cost comparison surface drainage systemsCost Comparison Results

  1. Cast in-situ trench drains $393,000
  2. Grated pit & pipe system $377,000 (4% cheaper than cast in-situ trench drains)
  3. ACO Drain® $340,000 (13% cheaper than cast in-situ trench drains)

The ACO Drain® option was determined to be cheaper than the cast in-situ trench drains and grated pit & pipe system.

Click here for further information and a breakdown of all costs

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