How to Install a Stormwater Pit

Stormwater Pits are a fundamental component of any stormwater infrastructure project, and are one of the most common items produced by Civilmart today. High-quality, durable and reliable Stormwater Pits are essential to ensuring the stormwater infrastructure in any city, town or rural area will stand the test of time. Despite their commonality, many people are still unsure exactly what Stormwater Pits are used for, or how to install a Precast Stormwater Pit. Let’s dive in and find out exactly how Precast Stormwater Pits work, and the installation process behind them.

What is a Stormwater Pit?

A Stormwater Pit is a water collection and storage device that holds all the runoff stormwater before it is diverted through attached Reinforced Concrete Pipes. They’re designed to cope with large amounts of stormwater runoff to prevent flooding, while the pipes attached drain the water away. Stormwater Pits are made of precast concrete, and come standard with “knockouts” – holes in the walls of the to install pipes.

How do Stormwater Pits Work?

When it rains in a natural environment, stormwater is absorbed into the earth. In urban areas and on man-made surfaces however, stormwater is unable to be absorbed. This creates what’s known as stormwater runoff. Without proper management of stormwater runoff, the risk of flooding is increased, as is the chance of contamination of local waterways. Stormwater Pits are key to ensuring stormwater runoff is captured and diverted appropriately. Stormwater Pits are placed strategically to collect stormwater runoff and contain the flow, as the pipes attached divert the water away.

Types of Stormwater Pits

There are a variety of different styles of Stormwater Pits, all specially designed for a specific job. Types of Stormwater Pit include:

Precast Knockout Pits

Precast Knockout Pits are the standard Stormwater Pit. These pits feature “knockouts” for easy installation of Reinforced Concrete Pipes. The knockout areas on the pit are thinner, and are able to be broken open with a hammer as necessary. Precast Knockout Pits are one of our most common items, as they are used in a wide variety of civil infrastructure and stormwater projects.

GRC Stormwater Pits

Glass Reinforced Concrete (GRC) pits serve as a lightweight, easy-to-install alternative to traditional precast pits for smaller scale uses. They’re made from a concrete and glass fibre composite, and are designed (in most cases) to be lifted by one or two people, making them easy to move and install on-site. As GRC products are manufactured without steel reinforcement, it is also ideal for installation in areas normally prone to corrosion.

Side Entry Pits

Side Entry Pits are built into the roadside to collect stormwater runoff from street gutters. Side Entry Pits are commonly seen in residential and urban areas, built into the kerb to collect stormwater runoff from roads. Civilmart Side Entry Pits are supplied in Class C and can come as a Double Top Unit for easier installation.

Custom Stormwater Pits

Civilmart are able to custom-design and manufacture stormwater pits to suit almost any individual project. Unique penetrations, wall thicknesses, exposure classifications and more can all be customised to suit a specific job. Civilmart are experts in creating custom products that fit our clients’ needs perfectly, get in touch with our friendly team today for more information on our custom capabilities.

How to Install a Stormwater Pit

A typical installation of a Stormwater Pit follows these basic steps:

1. Check that the foundation and bedding material is undisturbed and ready for installation.
2. Prepare the stormwater pit for lifting via lifting clutches. Ensure the pit is not susceptible to striking any other objects.
3. Lift the stormwater pit into position, guiding it onto the downstream pipe. Lift the pipe slightly to enable the joint to be made before the base touches the bedding. Ensure the end of the pipe stops slightly short of the benching inside the base. Check that there is enough clearance underneath the pipe to apply sealant.
4. Ensure that the pit is sitting level. Use a spirit level to check, placed on top of the rim. Also check the downstream and upstream invert levels are in accordance with the design.
5. For modular pits with knockout sections, mark the size and location of the pipe on the thin knockout section of the pit wall. Use a proper tool (like a ball peen hammer) to slowly and gently break the pit wall. Use a small sledge hammer to make the initial break in the centre of the knockout.