Friday, February 1, 2013

Project Flashback: Septic Tank Installation

As we’re in between remodeling projects for the moment (translation: I haven’t worked up the enthusiasm to paint anything), it seems like an opportune time to step into the WayBack Machine to see what other projects we knocked out early on.

I’ve already blogged about the work we did on our porch, including new screens and paint. While that was underway, we also came to learn that our septic tank wasn’t in the best shape.

Here’s what it looked like when we bought the house. That white thing sitting on top was a dilapidated thing used to haul stuff on top of your car, like if you were going camping. It was filled with water and various bits of debris. Gives a nice homey touch, dontcha’ think? I can tell you that all the insects loved it.

We had noticed some cracks in the block that was above ground, and initially thought they could be patched. But after we chatted with Fernando and few others, we came to learn the real story.
It seems that when the original tank was installed, shortcuts were taken (surpise!). For instance, no Rebar was used in the walls and little or no concrete was poured in between the blocks to add stability. Basically, a few swift kicks to the corners and this thing might collapse. Okay, maybe that’s a wee bit of an exaggeration, but it certainly wasn’t in good shape. And I don’t know about any of you, but having a working septic tank is one of those things that’s kinda’ important, no matter where you live.
Through a lead provided by Fernando, we found a contractor who could do the job. He had installed tanks in the area and agreed that there was no way the existing one could be repaired. After providing us with a diagram of what he thought needed to be done, as well as a detailed list of material and labor costs, we decided this was the guy for us.
So as to not be without a septic system for the time the new one would be built, a bit of an inconvenience to say the least, it was agreed that augmenting the existing pipes to run to the new tank would be one of the last steps and something David would take care of. That would give him time to put together a game plan, plus get the supplies he needed for that part of the job.
Now if you live in the States and need a new septic tank installed, the contractor would more than likely bring in a backhoe, dig the hole, then install a pre-fab tank and connect the lines. Badda-bing, badda-boom -- job done.
Here in Corozal, one might say the process takes a bit more time and effort. For instance, we agreed to have an 8’x8’x6’, three-chambered tank, plus a “soak away” chamber (more on this in a minute). With heavy equipment, such as backhoes, almost non-existent, the hole for this would be dug by hand. Yup, a crew of four guys, two going at it at one time, started to break ground and dig the pit.

By the end of the first day, they managed to dig down about three feet. On the second day, instead of hitting black dirt, the limestone layer appeared.

Quite a pile, no? And I must mention that the guys were doing all this digging while it was beastly hot and humid.I was breaking a sweat just sweeping the floor. Haven’t a clue how they managed without falling over from heat exhaustion.
While the digging was going on, another couple of guys went out to buy and deliver cement, sand, and gravel, all loaded in the back of a pick-up truck. These would be used, in part, to pour the floor of the tank.

Then they went out to get cinder block. No pre-cast blocks here. All are hand-made.

After another day or so of digging, they hit the water table at about 5 ½ feet. At that point, they put down some plastic and built a rebar frame to go over it. Rebar – a word and a product that I’ve come to appreciate. Anyhoo, once the frame was built, they poured cement over it and smoothed it out.

With the floor in place, the crew could then start building the three chambers with the cinder block. The way this works is that instead of having a drain field, all the stuff from these tanks gets piped into a separate chamber, called a “soak away.”

While all of this was going on, David and Fernando started digging trenches to see where and how the existing pipes were located and installed.

Ideally, we should end up with one 4" pipe that goes to the septic tank. However, we found out that there are three 2" pipes coming from the sinks. David got to work to figure out how to make those connections, plus get the slope of the pipe correct.

Back to the septic tank construction. Contrary to its appearance, this is not a burial pit, but rather the initial dig on the "soak away" chamber.

 Once the guys reached the soak away's required depth, they started creating the footers.

Here you can see the walls of the soak away, along with the pipe leading from the three chamber septic tank. To the right, more boards are in place for the tank cap, along with the forms that will create the access hatches.

Instead of having two separate slabs to cover the tanks, we opted for one. The crew finished spreading the top coat.

Close-up of the forms for the hatches. Over the lower boards, the crew assembled rebar grids, then took the used concrete bags to line the mold, then poured in cement.

After the crew left for the evening, this happened:

The culprit: Sam. He decided to walk across the wet cement. Fortunately, David was able to smooth out the surface and no one was the wiser.

The aforementioned cement bags. I was surprised that these were used as the release agents for the caps, but sure enough they peeled right off when the cement was dry.

Okay, this shot tells a couple of stories. First, that the crew filled each chamber with stones (and later gravel). The other is that pipe you see, which leads to…

 ...the other part of this project -- locating the original waste and water pipes, then reconfiguring them to go into the new septic tank.

Fortunately, my husband is a math marvel and got everything figured out. In addition to the math, there was also the challenge of the old pipes being too small in diameter, which meant all kinds of funky fittings that he had to contend with and get pipe for.
There were five separate lines that feed into the old system. David needed to figure out how to have them all connected and lead into one pipe to the new system. Angles, slopes, and lots of other math was involved. Needless to say, I was NOT in any way part of that ciphering. As soon as David started explaining the formula for determining the slope (1/8' for every foot), my brain cramped.
Here is what were the separate water and waste pipes from the spare bed/bathroom, which are now going into one feed.


Did I mention that due to limited part availability that David could only work with 45 and 90 angle pipes? Like the job wasn't challenging enough.

But all the piping worked out perfectly and, VOILA, our finished system. Purty, ain't she?

All told, it took nine days from start to finish for the entire project.

Not long after the new septic system was installed, we asked Fernando (pictured on the right) and his son, Hugo (pictured on the left), to demolish the old one.
What we thought might take a few days, took only one. The reason? For starters, the cap for the tank was being held together with tying wire, not Rebar. A few swift hits with a sledgehammer and it fell apart. And, much like we suspected, the concrete block wasn’t filled with cement, nor had any rebar reinforcements.

Once the demolition was complete, the area was filled with left over dirt from the new tank installation, sand, and gravel.

This is  what it looks like now:

It's come a long way, baby.


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  2. Elizabeth,
    This is one of this best blow by blow articles I have found. As a soon to be resident of Belize, I search for info on dealing with the concerns of building a home. The pictures were excellent. Please post other projects you do.

  3. Wow, this looks like a tough job in a humid climate. I'm glad I didn't have to take this project on. It looks well done though, even though there were a few hiccups along the way. I hope it serves you well.