Professional Carwashing & Detailing

Solve self-serve sediment odors

October 11, 2010

In a typical self-serve carwash, with a central basin in the middle of the bay, it is extremely difficult to have a satisfactory sediment removal and odor control system.

In a conveyorized tunnel carwash or an automatic rollover installation, the water is returned to a reclaim vault/tank where the sediment and reclaim water can be treated consistently.

In a self-serve facility where there is no reclaim vault/tank, it is not only difficult to control the sediment and odor, but is also a maintenance headache.

In addition, an odor control system that eliminates odor consistently is almost impossible.

Bacteria and chemicals
Odor from the pits can be attributed to two sources:

  • Biological; and
  • Chemical.

Bacteria (the biological source of the smell) creates foul odor in a carwash for obvious reasons. The chemical odor develops from two possibilities — the first is from one type of chemical spilling into the bay; the second can be from a chemical reaction.

Bays should be cleaned regularly to prevent the build-up of bacteria and chemicals.

Because bacteria is more likely to be a problem during the warm months of summer, experts recommend that the pits be cleaned twice a year; once before summer and then once again at the end of summer.

Another easy way to prevent smelly chemical reactions from happening in your pit is to strongly discourage illegal dumping.

Put up signs in a conspicuous location, such as the coin box, reminding customers that dumping is illegal and will not be tolerated.

Remember that whatever is dumped at your site is your responsibility. If customers are dumping oil, grease, antifreeze, or other waste products at your site, you’ll be the one left to pay the bill from the Environmental Protection Agency (EPA) or Department of Conservation (DEC).

The self-serve treatment
A truly horrible stench from a bay pit will drive away customers at your self-serve.

While the combination of aeration and enzyme/bacteria will eliminate and control the odors, as well as petroleum hydrocarbons and other organic contaminants, owners still fight the battle of bacteria that is constantly trying to establish itself in the sludge sediment within the reclaim vaults and pits at carwashes.

Typically, a self-serve facility consists of multiple bays that have a catch basin in the center of the bay where the water and sediment settle.

From there, the used water is sent to the sewer with possibly an oil/water separator prior to disposal.

The main problem when trying to treat this water and sediment is that the water flow is not steady.

On an average busy day the used water will flow through the basin very quickly, so there is not sufficient time for treatment of the water.

We encounter the same problem with trying to treat the sediment. The odor from the sediment is also very difficult to eliminate simply because much of the enzyme/bacteria wash away.

Applying enzyme/bacteria (or other odor control products) over a period of time and maintaining a strict schedule will allow the enzyme/bacteria to establish a colony that is able to consume the petroleum hydrocarbons as well as other organics, thereby reducing odor by a substantial amount.

Starting fresh

When building a new ground up facility there is a better way. A strip/trench drain needs to be laid through all the bays and exiting into a holding tank/vault.

The catch basins are then constructed in a cone shape so that the water and sediment are flushed into the strip drain and continue down to the holding tank/vault.

At this point, the sediment can either be pumped out by a service company or pumps can be placed in the holding tank/vault to pump out the sediment on a preset timetable into filter bags, which can then be disposed of according to local ordinance.

The odor emanating from the holding tank/vault can be controlled by adding aeration 24/7 as well as enzyme/bacteria on a weekly/monthly basis.

Andy Pazz is the owner of Laguna Ltd. and has written an e-book: “Building a Successful Tunnel Carwash.” If you have additional questions for Andy, please e-mail