A pit cover might seem like a straightforward product — a lid that sits on top of a pit. But specify the wrong one and you have a safety risk, a compliance problem, or a cover that fails prematurely under load.

This guide covers the key factors that determine the right pit cover for your application: load rating, access requirements, pit dimensions, and material considerations.

Why Pit Cover Specification Matters

Pits are used across a wide range of civil and agricultural infrastructure applications — irrigation pits, stormwater pits, service access pits, and agricultural drainage pits. In each case, the cover serves two functions: it provides structural support for loads above the pit, and it provides access to the pit for maintenance and inspection.

Getting the specification wrong can mean:

• Structural failure — a cover rated for foot traffic that is driven over by a tractor or vehicle can crack or collapse
• Safety incidents — a cover that is too heavy to lift safely, or that has no lifting provision, creates a manual handling risk for maintenance workers
• Compliance issues — in some applications, pit covers must meet specific standards for load rating, slip resistance, or access dimensions

Load Ratings Explained

Pit covers are rated by the load they are designed to carry. The most common rating categories for precast concrete pit covers are:

Pedestrian (Class A)

Rated for foot traffic only. Suitable for pits in areas where no vehicle access is possible — inside buildings, in pedestrian-only areas, or in remote locations where vehicle access is physically prevented.

Light Vehicle (Class B)

Rated for light vehicles — passenger cars and light commercial vehicles. Suitable for pits in car parks, driveways, and light-traffic areas.

Heavy Vehicle (Class C/D)

Rated for heavy vehicles — trucks, agricultural machinery, and construction equipment. This is the most common specification for irrigation and agricultural pits, where tractor and truck access is routine.

If you are unsure what load rating you need, specify for the heaviest vehicle that could realistically access the area — it is much cheaper to over-specify at the design stage than to replace a failed cover after the fact.

Access Requirements

Opening Size

The opening in the pit cover needs to be large enough for a person to enter the pit safely for maintenance and inspection. Australian standards specify minimum access opening dimensions for confined space entry — typically 600mm × 600mm as a minimum for a person wearing personal protective equipment.

For pits that require regular access, a larger opening makes entry and exit easier and reduces the risk of injury. For pits that require only occasional inspection, a smaller opening may be acceptable.

Lifting Provision

Pit covers need to be removable for access. For small, lightweight covers, a simple lifting recess or handle may be sufficient. For larger, heavier covers, a mechanical lifting point — a cast-in lifting eye or a recessed hook point — is required.

Consider who will be removing the cover and what equipment they will have available. A cover that requires a forklift to remove is impractical for routine maintenance by a single operator.

Slip Resistance

In wet conditions, a smooth concrete surface can be slippery. For covers in areas where people walk — particularly in irrigation areas where the ground is regularly wet — a textured or broom-finished surface improves slip resistance.

Milcast Pit Cover Range

Milcast manufactures pit covers in a range of standard sizes to suit the most common pit dimensions used in Riverina irrigation and civil infrastructure applications. Our standard range includes:

• 600 × 900mm — the most common size for standard irrigation pits
• Custom sizes — for non-standard pit dimensions or special access requirements

All Milcast pit covers are manufactured from reinforced concrete to Australian standards. Load ratings are available to suit pedestrian through to heavy vehicle applications.

Matching Cover to Pit

The pit cover must match the pit it sits on — not just in plan dimensions, but in the seating detail. A cover that overhangs the pit opening by the correct amount will distribute loads to the pit walls; a cover that is undersized may drop into the pit under load.

When ordering pit covers, provide:

• The internal dimensions of the pit opening
• The wall thickness of the pit (to determine the seating width)
• The required load rating
• Any special access or lifting requirements

If you are ordering pit covers to suit Milcast pits and risers, we can supply matched covers that are designed to work together as a system.

Talk to Us

If you are specifying pit covers for an irrigation or civil infrastructure project, our team in Finley can help you get the specification right. We supply pit covers to irrigation districts, civil contractors, and farmers across the Riverina.

Call us on (03) 5888 3051 or request a quote through our website.