Types of surface water drainage
Pros and cons with an independent cost comparison
There are two main approaches to surface water drainage:
- 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. - 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.
Here are 5 surface water drainage options and their pros and cons:
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.
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:
A spoon drain is a formed swale in the pavement, often leading to a grated pit.
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.
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 Results
- Cast in-situ trench drains $393,000
- Grated pit & pipe system $377,000 (4% cheaper than cast in-situ trench drains)
- 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
