Wash bay design is dependent on what is being washed, the size of the items being washed, the amount of solids on the items being washed and the amount of oil/grease or chemicals on the items. For example; a tracked excavator can hold several cubic feet of mud on the tracks and very little oil or grease. An oilfield service company may encounter large amounts of oil and grease and very small amount of solids. These things should be considered as they are very different and require a very different design.
Wash Bay design for light solids loading
Wash bay design for washing vehicles or equipment with low amounts of soilds and low amounts of oil and grease. For example, washing the outside of cars, trucks or aircraft. This would be a standard design. Typically consisting of a sized collection pit in the washing area that would gravity drain to an in-ground 3 chamber separation pit.
If you are discharging to the sanitary sewer, this may be all you need. Check with your cities public works department or sewer department for local requirements and permits.
If you plan to recycle the wash water, the water can be pumped directly from the 3 chambered separation pit to a recycle system. See recycle systems for more information.
Wash bay design for heavy solids loading
Wash bay design for washing earth moving equipment with heavy amounts of mud and dirt require a different design. There are many options, such as center collection, front collection, or side collection of the mud. The choice depends on the available space and the anticipated amount of mud. The collection areas are usually built with a ramp to allow a front end loader, such as a Bobcat, access to the mud for removal. Mechanical augers are also an option in very heavy mud applications.
Again, check with your cities public works department or sewer department for local requirements and permits.
Wash bay design for heavy oil and grease loading
Wash bay design for oil field equipment, motor rebuilding, transmission repair and motor rebuilding. These all generate large amounts of oil, grease or other fluids. In these applications, it is important that the fluids drain away from the workers feet to avoid excessive contact and to prevent a slip hazard.
With heavy amounts of oil or fluids a 3 chambered separation pit is usually not enough to meet local sewer requirements. An oil water separator is usually required to meet permit requirements. See oil water separators.
Concrete Design for Wash Bays
Concrete foundations must be designed for the anticipated loading. The thickness of the floor, the rebar design are all part of the structural aspect of designing a wash bay floor.
A 1 % slope to the collection area is standard. Broom finish is also standard, never use a slick or polished finish in a wash bay as these will create a slipping hazard.
American Concrete Institute (ACI) has guidance for concrete in wet areas such as wash bays. This can be found under ACI 350 Environmental Concrete. Note that most contractors will use ACI 318 Building Design, and not ACI 350. ACI 350 takes into account the fact that concrete cracks as it dries. If not controlled and sealed, cracks can lead to uneven swelling caused by water under the slab. It can also lead to future environmental problems such as impacted soils or groundwater under the wash bay.
Standard Wash Bay Design Packages
Wilson Environmental offers several off-the-shelf wash bay design packages. These packages can save you money when a standard design is appropriate.
- Center Drain Designs – Good for small to medium size facilities where concrete loadings are not an issue.
- Side Drain Designs – Good in limited space situations and where large amounts of mud and dirt are expected.
- Back Drain Designs – Also good in a limited space situation and in cases where water recycle is required.
- Pre-Wash/Final Wash Designs – Used in larger high volume facilities where a pre-wash is needed. By separating the pre-wash from the final wash, water treatment costs can be kept to a minimum.
- Heavy Solids Designs – This design incorporates a heavy solids dewatering and handling area. Used where excessive amounts of mud and dirt are anticipated.
- Wash Pan Designs – This design uses a metal pan instead of a sump system. This system can be disassembled and moved. This design is generally used when a move is anticipated or the operator does not want to make capital improvements on the property, as in some lease situations.
Whatever your requirements, we can help you select a standard wash bay design package. If a standard package is not a fit for you, we can design and build a custom wash bay design solution.
Contact us today to get started.