Our guide to vehicle wash down bay design

Designing an effective vehicle wash bay is essential for businesses that need to manage vehicle cleanliness and environmental compliance. A well-designed wash bay not only helps maintain equipment and vehicles but also protects the surrounding environment by treating and managing wastewater safely. 

This guide covers the key components of a functional wash bay, from selecting the right layout and equipment to implementing systems for efficient wastewater management and regulatory compliance. No matter your industry, understanding the basics of wash bay design will help ensure your facility operates smoothly, sustainably, and cost-effectively.

Find out how Cleanawater can help you with vehicle wash down bay design and compliance.

Key elements of vehicle wash down bays

The most crucial element of a vehicle washdown bay is effective wastewater management as it ensures that contaminants like oils, heavy metals, and chemicals are removed from wash water before they enter local waterways or sewage systems. This is essential not only for environmental protection but also for regulatory compliance, as most industries are subject to strict guidelines around wastewater disposal to prevent pollution.

Therefore, an authorised discharge point must be negotiated with the local water authority, or a discharge tank must be installed. This tank collects treated water for disposal by truck. Local water authorities have specific processes for obtaining a wastewater discharge license, with water quality specifications and pre-treatment requirements.

Every wash bay has a silt sump to capture soil and other solids from the wastewater before it passes through pre-treatment. Wash bays are graded so that water flows to a low point where it enters the silt sump. Solids collect in the bottom of the sump, and a pipe near the top transports water to a collection pit for pre-treatment.

Local water authorities specify pre-treatment solutions, which normally include oil water separators. These solutions may also require pH control and other site-specific treatments to ensure that wastewater quality remains within specification.

Cleanawater process for vehicle wash down bay implementation

It is advisable to work with an experienced partner in wash bay design and water recycling systems to ensure compliance with regulators. Cleanawater has over 20 years of experience in wastewater solutions. Our track record includes the installation of multiple vehicle wash down bays. We follow a process developed from experience to deliver successful projects to each client.

Step 1: Initial Consultation

We discuss the client requirements; view the proposed site; and gain an overall understanding of the scope of the project.

Step 2: Inground services check

We determine if any pipes or cables are installed underground at the proposed site, which may impact construction. As a result of this step, sites may be moved or reconfigured.

Step 3: Water availability check

We assess the water flow and pressure requirements based on the expected volume of vehicles and consider future business expansion. Roofed vehicle washdown bays have the potential for rainwater harvesting, which may also be evaluated at this point, in addition to the potential for recycling.

Step 4: Discharge point check

This is a key step in terms of compliance. Negotiations with local water authorities will clarify pre-treatment requirements and the location of a discharge sewer.

Step 5: Stormwater point check

This is a critical step for unroofed wash bays. Provisions must be made for large volumes of rainwater so that the pre-treatment system and wastewater system are not overloaded. First flush diversion enables wash bays to capture potentially contaminated water but allows clean water to flow to stormwater sewers.

Step 6: Bureau of Meteorology data check

We check the BOM Intensity–Frequency–Duration data to set design criteria regarding expected rainfall patterns for unroofed wash bays.

Step 7: Design and quotation

Our team collates all of the information and checks conducted up until this point to produce a detailed design of the vehicle wash bay. All parameters are checked against compliance criteria to ensure the wash bay meets and exceeds local water authority requirements. Design elements include the size of the wash bay, the size and location of the silt sump, pre-treatment solutions, and discharge systems of wastewater and stormwater as appropriate.

Step 8: Installation

The installation of wash bays is completed by Cleanawater teams. The bay is built according to design drawings and is signed off by engineers. Cleanawater participates in the inspection process and sign-offs by local authorities.

Step 9: Commissioning

Commissioning of vehicle wash bays involves testing each element of the system. The wash bay performance is evaluated, and the functioning of each element is checked. Staff training is also carried out to ensure each person fully understands how the system works.

Step 10: Live and post-live inspections

We ensure that the system is operating as per design - this includes checking the wash pads, flush diversion system, and any related plant equipment. We’ll ensure that local water authorities are satisfied with the compliance.

Step 11: Service and maintenance

Ongoing service and maintenance contracts are often required by local water authorities as part of their wastewater license application. Cleanawater provides these services to ensure equipment operates as expected and to pick up any defects before an environmental incident occurs.

Does a heavy equipment wash bay design differ from a car wash bay design?

A heavy equipment wash bay design differs significantly from a car wash bay design due to the size, weight, and type of contaminants involved. Heavy equipment wash bays are typically larger and reinforced to accommodate the greater weight of machinery like excavators, bulldozers, and trucks. They often feature more powerful water pressure systems, specialised filtration, and sludge management solutions to handle tougher grime, mud, and oil. 

Additionally, these bays may include features like high-capacity oil-water separators and extra drainage to deal with the heavy-duty washing requirements of industrial equipment.

What is the ideal design for portable wash bays compared to permanent wash bays?

The ideal design for a portable wash bay or unroofed wash bay focuses on flexibility, ease of setup, and mobility, making it suitable for temporary sites or operations that require frequent relocation. In contrast, a permanent wash bay is designed for long-term use, with more robust construction, larger wash water drainage systems, and advanced filtration options.

Key differences in design:

Portable wash bay:

• Lightweight, modular components for easy transport and assembly.

• Temporary drainage and filtration solutions in the wash bay area.

• Suitable for short-term or project-based use.

• Flexible sizing to fit various site conditions.

Permanent wash bay:

• Reinforced structures designed for long-term durability.

• Advanced drainage, sludge management, and filtration systems.

• Customisable to handle high volumes and heavy equipment.

• Fixed installation with higher water capacity and treatment efficiency.

Contact Cleanawater for expert advice

Cleanawater has more than 20 years of experience in Australian wastewater systems. We have worked with clients and local water authorities across the country to implement wash bays that discharge into municipal wastewater sewers. 

Our track record and expertise make us the ideal partner to help you set up your vehicle wash bay system. Contact us today for more information on wash bay construction and design.