Channel Drains for Car Parks

Public or private car parks, whether ground-level, subterranean or multistorey, generally feature large, asphalt or concrete surfaces. These don’t absorb water, making them vulnerable to pooling and flooding during heavy rainfall and even lower-grade surfaces such as compacted aggregate often require drainage. 

Channel drains provide an efficient solution by collecting and directing surface water, ensuring the safety and structural integrity of the car park.

Let’s look into the types of channel drains that are suitable for parking areas and the benefits they bring.

How Do Channel Drains Work?

Channel drains, also known as linear or trench drains, consist of a long, narrow channel covered by a grating. Water runoff from the parking area flows into the channel along its length and is directed to an underground drainage system, soakaway or water treatment facility. This design is more efficient than traditional single-point drainage systems, such as gully drains.

What Are The Benefits Of Using Channel Drains In Car Parks?

1. Effective Water Management

Channel drains quickly collect and redirect surface water, preventing pooling and flooding. This is particularly important in large car parks where water accumulation can cause significant disruption.

2. Enhanced Safety

Standing water increases the risk of vehicle skidding and pedestrian slips, particularly in sub-zero temperatures. Channel drains minimise these hazards, creating a safer environment for all users.

3. Prevention of Structural Damage

Flooding can weaken the sub-base of car parks, leading to cracks and potholes. Proper drainage protects the surface, reducing maintenance costs.

4. Compliance with Regulations

Channel drains support SuDS compliance by managing surface water runoff effectively, ensuring environmental and legal compliance.

What Materials Are Channel Drains Made Of?

Channel drains are manufactured from various materials to suit different applications and load requirements:

• Polymer Concrete

A robust composite material, ideal for moderate to heavy loads.

• Concrete

Durable and cost-effective, suitable for large-scale car park projects.

• Polypropylene (PP) and Polyethylene (PE-HD)

Lightweight, corrosion-resistant materials for light-duty applications.

Grating covers, which protect the channel and allow water entry, are typically made from:

• Galvanised Steel

Affordable and rust-resistant, suitable for light to medium traffic.

• Ductile Iron

Highly durable, ideal for areas with heavy vehicles.

• Composite Materials

Lightweight, eco-friendly options with versatile designs.

What Load Rating Is Right For A Car Park?

Channel drains are classified by load ratings under BS EN 124:2015 to ensure they meet specific application demands:

• C250 (25 tonnes)

Suitable for private car parks with light traffic. 

• D400 (40 tonnes)

Ideal for public car parks with regular vehicle use.

• E600 (60 tonnes)

Designed for HGV parking areas.

It’s important that the appropriate load rating is chosen to prevent damage to the grating or collapse of the channel.

Installing Car Park Channel Drains

For optimal performance, channel drains should ideally be incorporated into the car park’s initial design. This approach allows for:

• Proper grading to direct water towards the drains.
• Strategic placement for efficient water flow.
• Easy connection to underground drainage systems or soakaways.

Channel drains are widely used in multistorey car parks, where they will be incorporated within the design and construction. They can also be retrospectively installed in ground-level parking lots where a drainage problem may have developed; their shallow depth makes installation straightforward, minimising disruption.

Maintaining Car Park Channel Drains

While channel drains are designed to be low-maintenance, no drainage system is ‘no-maintenance’. Following a simple maintenance routine will ensure your channel drains give the best performance over a longer period.

1. Regular Inspections

Maintaining channel drains in car parks is essential to ensure proper drainage, prevent flooding, and extend the lifespan of the drainage system. Regular inspections should be conducted at least quarterly or after heavy rainfall to identify blockages, cracks, dislodged grates, or any signs of wear and tear. Inspect the outlet pipes to ensure water flows properly out of the system. 

1. Clearing Debris

Surface debris such as leaves and rubbish should be removed regularly, while sediment and smaller obstructions inside the channels can be cleared using a pressure washer or hose. The outlet pipes may also require cleaning.

1. Maintaining Grates

The condition of the grates covering the drains must also be monitored. Loose grates should be tightened to ensure safety and damaged grates should be replaced to avoid injury and prevent larger debris from entering the channels.

1. Repairs and Damage Control

Prompt repairs are crucial for maintaining the system. Cracks and leaks should be sealed immediately to prevent water seepage and structural damage, and damaged sections of the channel drains should be replaced as needed.

1. Seasonal Maintenance

Seasonal maintenance is another key consideration. During winter, it is vital to clear snow and ice from drains to prevent freezing and blockages, while in autumn, focused removal of leaves can avoid clogging issues.

1. Professional Servicing

Professional servicing should be scheduled at least once a year for thorough inspections and deep cleaning, especially in high-traffic car parks. Professionals can identify and address underlying issues that may not be visible during routine checks.

1. Record Keeping

Keeping detailed records of inspections, cleaning and repairs helps monitor the drainage system's condition over time and ensures proactive maintenance.