The house is not on the city sewer system which means we have a septic tank. Having had the "pleasure," in my past life of digging up the septic tank at the most inopportune times to be pumped, I suggested that we have a pipe installed to make it easier to pump, since we had to locate the tank opening anyway. Mind you, this started as part of a project to locate the septic tank/leach field which is part of the landscape planning project for the area between the house and the street; specifically planning the water diversion area for managing the monsoon waters that flow through the front area. (It is all so interconnected. Hopefully I didn't lose you on this one.

Let me explain. A riser is a 24" heavy duty tube that fits over the take out hole and fitted with a secure cover. It allows access to the septic tank for general maintenance without digging to China each time. Should be simple enough, right? This is where it became fun.
Take a step back. During the house inspection, the septic tank had to be certified as recently pumped and fully functional. According to the inspection report (March 2013), the tank had been pumped September 2012. That means it had been fully cleaned out of everything within the tank. (Keep that in mind.)
Fast forward to installing the riser.
1. The take out hole was only 8" in diameter. Probably code in 1976, but not so much now.
2. The riser tube is 24" in diameter. It needs to fit tightly into the hole. The hole needed to be made bigger.
3. Some idiot allowed trees to grow over the tank. Big no-no due to roots going for the water. We had already removed one tree that was right at the end of the big dig.
4. Upon inspection, two things were evident. First, the Oleander right in front of the house (in background in picture above) had grown roots into the tank right at the point of the take out hole. There was no way that a hose could be inserted into the tank for proper service. Second, the tank had not been properly pumped in forever, despite the "certified" report to the contrary.
5. Upon rereading the home inspection report, the shower drains were slow and had to be snaked. It appeared to the pipe to the tank had roots recently removed. Makes sense when taking into account #4 above.
So what started as a project to make our lives easier in the future ended up being a bit of a set back. In the end, it turned out to be a good thing. The Oleander has been removed. We now have a properly cleaned tank and a riser that will make the job easier for the next service call, in about 5 years. We still don't know the location of the leach field, but we do know it was recently replaced. We will just need to tread lightly when shaping the front area for water abatement.
At least now we can move forward.