Published June 2007

Ill Winds Blow

(page 66)

A poster asks what to do when a country club customer is fed up with grease trap exhaust odors

This feature in Pumper® reports noteworthy conversations that take place in Pumper Discussion, an e-mail based forum for industry professionals sponsored by COLE Publishing. Pumper Discussion provides for the exchange of information and ideas on septic and drainfield installation and maintenance, trucks and equipment, portable sanitation, chemicals and additives, and much more. To find out more about Pumper Discussion, or to subscribe, visit www.pumper.com/discussion.php.

Information and advice in Overheard Online is offered in good faith by industry professionals. However, readers should consult in depth with appropriate industry sources before applying such advice to a specific business situation.

Vacuum Exhaust Odors Causing Problems

Question:

We pump grease traps and poultry waste with the same truck we use for daily pumping at a country club. We go to the country club very early in the morning, but have had complaints regarding vacuum pump exhaust odors. We’ve tried fragrances in the separators and vacuum pump oil fragrances without positive results. I’d like some additional ideas; we are told a 55-gallon drum charcoal filter provides too much backpressure on the vacuum pump. Unfortunately, the clubhouse air intakes are directly above the holding tanks. Maybe we are not using the correct odor-masking agent?

Answers:

We’re sometimes forced into doing grease traps. Grease is the single nastiest thing I have ever experienced. I don’t think it’s possible to hide the odor of 1,000 gallons of decaying animal. If you find a way let us know.

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Have their building’s air circulation shut down while you pump and for a bit after you are done. It is the only sure way. If building designers weren’t hampered by university educations, they would put the grease traps and the induct vents miles apart, and the maintenance people wouldn’t have this problem.

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What is the flow rate of your vacuum pump system? Also do you know the maximum backpressure for your pump? You may be able to utilize a smaller activated carbon scrubber rather than a 55-gallon drum system.

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Part of the grease odor is from too little maintenance to the trap. We all know nobody wants to spend a buck, and customers may think it’s all right to abuse the trap. Have you taken a sample of the grease to a lab to see if it’s just grease and not bleach or antiseptics? Is their dishwasher a high-water-temperature model, or do they use chemicals? The low temperature chemicals kill off any bacteria in the grease trap, and for it to stop smelling when it’s being pumped. Talk to the clients and find out if cleaning chemicals they add to the grease trap are causing the odors. We have almost all of our grease trap clients using bacteria with a fragrance and on an auto-drip system, so it’s always going into the trap. The result is fewer odors coming from the truck.

System Has Serious Problems

Question:

I have a couple of friends in the excavation business who have had a situation come to light. They did a repair job on a pressure dose system. The system was installed a couple of years ago when the house was built. It worked fine for about a year. When they inspected the system, it was functioning well, but showed some signs of problems. They went in and placed an L-shaped drainage area at the end. They dug down about 14 feet and backfilled it with sand and gravel. This worked for about another year. Just so you know, the ground is mostly swampy muck and the house and system are in a flood area with a possible spring underneath. The homeowner now is suing the excavators because they worked on the system last. How well do pressure dose systems work in this type of ground and what would you do in this situation?

Answer:

First off, remember this: Water always behaves the same way. It has no mind of its own. While individual soils may behave differently, the same soil always behaves the same way. Sponges and tabletops always behave the same way, too. When a fully saturated sponge is sitting on the table and you pour more water onto the sponge, the water cannot go into the sponge. So it runs off onto the table. Neither can the water go into the table, so it runs across the top of the table.

If the water finds an obstruction, it will go around it if it can. If the obstruction surrounds the water and you continue to pour water onto the sponge, the water will pile up behind the obstruction, getting deeper and deeper.

If the water piles up to a point higher than the obstacle, it will run over the top of the obstacle and move on. It will not leave the table until it gets to the edge of the table and falls off. If the water encounters a seam or split in the impervious table top, it will “fall” into that split or seam. If this crevice goes through the tabletop, the water will continue its fall, presumably to the floor. If the crevice does not go through, it too will fill up and the water will continue to accumulate.

Swampy, mucky ground got that way, not from the water that the system added, but from the soil’s natural inability to quickly move water away and dry itself out and from the water that God put there. While the soil at this site may have had some inherent ability to move some small amount of water away, the increased flow from the system apparently overwhelmed the soil’s natural ability to transmit water.

Digging the drainage area may have created some new void spaces into which water could move. If the “drainage” is completely surrounded by the muck and swamp, it did nothing to promote meaningful drainage. It appears now that this additional capacity and the additional contact area’s ability to move more water has apparently also been overcome.

There is no indication in the post regarding the rationale for pressure dosing. Pressure dosing is a process by which effluent is uniformly distributed throughout the area covered by the distribution system piping. Pressure dosing does not alter the infiltrative capability of the soil or its ability to “drain.” We are not discussing pressure injection. This gets us back to the sponge.

Regarding your friend being sued, ask these questions and follow where they lead: How did this system get in this swamp muck soil in the first place? Who issued permits for this?

And here’s one last truth: No matter what a permit says should happen, water is dumb, and it cannot read a permit. But for sure, water always behaves the same way.