This feature in Pumper reports noteworthy conversations that take place at the Pumper Discussion Forum, an online forum for industry professionals found at www.pumper.com. Pumper Discussion enables exchange of information and ideas on septic and drainfield installation and maintenance, trucks and equipment, portable sanitation, chemical and additives and much more. Information and advice in “Overheard Online” is offered in good faith by industry professionals.

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Question:

I see a lot of trucks under 26,000-pound GVW with 2,000-gallon tanks. I am curious to know what these trucks weigh when loaded. Has anyone been stopped and fined? I have a 1997 GMC C6500 that scales 14,640 pounds empty. It has a 1,900-gallon tank, and if fully loaded, it weighs around 28,000 pounds. I looked at some of the weigh slips at the sewer plant and all of them weigh 17,000 pounds empty. I just got a Freightliner FL70 (26,000-pound GVW) and it appears to be a lot heavier than the GMC. I got it because it has air brakes. I’m thinking about putting a tank on it. But if it weighs 17,000 to 18,000 pounds empty and I add a 2,000-gallon tank, I think it would scale around 30,000 pounds loaded.

ANSWERS:

It depends on what kind of tank you’re adding. I know those GMCs are pretty heavy though; I used to have one and it was always overweight. And a lot of people out there build trucks that aren’t spec’d right in wheelbase and weight. Figure 8.5 pounds per gallon of septage plus the weight of the tank. That is how they calculate the weight of the tank loaded.
 
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My present vacuum truck is a GMC C6500 and rated at 25,995 pounds GVW. With tank and hoses and everything else, it scales at about 14,990 pounds. That gives me about 11,000 pounds more before exceeding legal load limit and staying under CDL. About 90 percent of my loads I scale under 26,000 pounds, but sometimes it will go as high as 28,000 pounds. Most trucks under 26,000 pounds have hydraulic brakes, and if you are fully loaded the brakes are on the weak side.

I ran an FL70 with air brakes rated at 26,000 pounds GVW. Everything on it is heavier than the GMC. I don’t know how they came up with a 26,000-pound GVW. I just don’t want to go to all that work putting a 2,000-gallon tank on it and find out it weighs 20,000 pounds empty.

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Most all septic trucks you see running up and down the road are not legal when loaded, even the ones that have a high-enough GVWR because they won’t scale out right per axle. I run what I call cheater trucks. They are 33,000-pound GVW trucks derated to 26,000 pounds GVW at the factory. They have the heavy suspension, bigger wheels and tires, air brakes/air ride and the most powerful motor and best transmissions. I have aluminum 2,800-gallon tanks so if they were loaded to capacity would be over 30,000 pounds. I run under CDL trucks for several reasons. The biggest is that insurance is way cheaper. To answer your question about staying under 26,000 pounds GVW, with aluminum you can go up to 2,350 gallons.
 
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Almost all the pumpers in my area have gone to the smaller trucks, under 26,000 pounds GVW. Cheaper insurance, cheaper to operate, less damage to driveways. You say that you have a 2,800-gallon tank. Do you ever run fully loaded? I have had several people saying I just need to bite the bullet and buy an aluminum tank. That is not practical for me.