pugboy wrote:The elongated ones I saw had ribs along the sides for reinforcement unlike the fatboy ones which are just plastic ball.
I guess they dont have any vertical load strength.
Ripped from the web:
Septic Tanks: Plastic or Cement?
This entry was posted on January 17, 2017 by GoToTanks Staff.
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If you’re like most people, you probably don’t give your septic tank much thought from day to day – that is, until something goes wrong. Once something goes wrong, chances are you’ll think about nothing else until you get the problem fixed.
Buying a new tank can be a daunting task. Septic tanks come in two options: concrete or plastic. At first glance, it might seem like there’s no real difference between the two. However, if you read on, you’ll see not only the pros and cons of each type, but also why plastic tanks are really the better option for your home.
Concrete Tanks
Pros
Concrete has been the standard building material for septic tanks for a long time now, and it’s easy to see why. First, concrete is long-lasting. With proper maintenance, a concrete tank can last for decades. So, not only are they durable, they are also resilient. Concrete tanks will hold up to the rigors of heavy machinery during installation, and should you have to work on part of your yard later, you don’t have to worry about accidentally punching a hole in the side of your tank. Also, because concrete is so heavy, once that tank is in place it is settled in with no fear of it (or it’s, err, contents) shifting in the ground.
Cons
They might be sturdy and strong, but that doesn’t mean they will last forever. When a septic tank goes bad, it’s not pretty. As they age, concrete tanks are prone to cracking and corrosion. This can lead to noxious wastes leaking out. Low quality concrete also has steel support struts, which are prone to rusting, causing a slew of new issues. Concrete tanks are also much heavier, which means a much more expensive and complicated installation. This weight also means much more difficult and expensive repairs, should a problem arise at some point during the tank’s life.
And speaking of lifespan, once it’s over, that weight means a complicated (and expensive) removal. So, even though these tanks are built to last, when a concrete tank goes bad or encounters a problem, it is potentially an extremely foul-smelling and inconvenient predicament that will cost you an arm and a leg to fix or replace.
Plastic Tanks
Pros
Plastic tanks have a lot to offer. Made from strong and high-tech polyethylene, plastic septic tanks offer a much more lightweight solution. This lighter mass means a much cheaper installation without the need for heavy machinery or equipment. In addition, because they are easier to transport, plastic tanks can be installed just about anywhere – even in more remote areas. This makes them the perfect choice for places like vacation cabins and island-based housing. Plastic tanks are also more resistant to the cracking, rusting, or corrosion issues that can plague concrete septic systems down the road, and can be installed as deep as three feet underground, which helps to protect them from the outside elements and dangers.
Cons
Even though they are cheaper and very reliable, plastic tanks do come with some concerns. Because they are so light, it is possible that a newer plastic tank can “float” in areas where the water table is higher, causing them to rise up and shift, making it unlevel. This can lead to structural and leakage problems down the road. Also, even though polyethylene is tested and strong, it isn’t quite as durable as concrete in all situations, which means it is more prone to damage under extreme conditions.