Your aerobic septic installer will begin by determining the dimensions of your property. If you are building a new house, it is advisable to speak first to your septic installer and water-well installer on the placement of water-related structures.
Do you have plans for the property? How many bedrooms will your home have? With more than three your system size usually increases. Will you install a water well? If so, the aerobic system and spray have to be one hundred feet away. This will affect placement so don't just drill a well wherever you want. Your aerobic installer and water well installer need to talk and plan things out. We have seen instances where the water well was put in the wrong place and ruined the whole job. Will you be installing a pool in the next five years? Will there be future additions to the home? Your septic contractor and any other contractors working on the project will discuss these topics. This discussion helps determine the necessary septic system size and how many G.P.D. (gallons per day) the system will have to treat. A 2500 square foot house with four bedrooms typically needs a 500 G.P.D. system, but in some areas, the same home may require a 600 G.P.D. system. The larger the house, the larger the system. The number of people living in the home is NOT a factor, as some might have you believe.
Installing the Aerobic Septic System
Before choosing the location to install your septic tank, your septic contractor will need to check local regulations and the soil quality. Most municipalities require tanks and leaching fields to be located a minimum distance from houses, water wells, streams, etc. The size of your septic system will depend on how many bedrooms are in the home, including any additions expected in the future. Your contractor should discuss this with you. Septic tanks are below ground and tank installation requires a backhoe to dig an adequate hole. Inlet and outlet pipes must also be planned for and laid during initial installation. Do not hesitate to ask your contractor about their plans for moving equipment on and off your property as well as any plans for digging and returning any soil and vegetation that might require relocation.
To ensure that you can easily find the opening to the septic tank, it is recommended that you have a ‘riser’ installed to bring the septic tank lid to just above the surface of the soil.
You don't want to skimp on this part of the house. We have seen systems installed too high, causing water to be held in the inlet pump coming from the home. The homeowner would have to continually snake the line to unclog it because of a lousy septic installation. More on this subject in the next section.
On any installation (one, two, or three tank installation), the first tank should be dug and the tank set when the hole is dug. A good installer will leave enough room on all sides of the tank so that one and a half buckets will fit in the hole. The reason for this is so he can pack the dirt with the weight of the backhoe arm, and the earth does not settle after the job is done. Good installers do this and the lazy ones don't. They make a hole just big enough for the tank to fit in and throw the dirt over it and leave. One reason they do this is lack of skill; they are afraid they will hit the tank and lack confidence on the machine. They also just don't care what it looks like later. It may seem done right when they go but it won't feel that way later. When it rains, a moat will form around it and water will sit there. After the first hole is dug, it should then be almost completely backfilled, and the ground consolidated with the backhoe or track hoe arm about 4 inches past the inlet hole for the pipe coming from the house. Then you dig back down with a shovel to the hole. That way, the pipe has an excellent foundation to sit on and won't move. By not doing it this way you guarantee an expensive repair later. Once the first tank is set, the hole for the second is dug, we repeat the process. We like to put about 4 feet between each tank. We do this because if anything happens like someone drives over the system and you have only a foot between the tanks it's impossible to replace the pipes between the tanks. You have to cut or chisel into the tank to accomplish a repair. We do this because of all the repairs we do and don't want to have to do on our systems. A lot of installers don't do repairs, so they don't think ahead on things. The only time you dig one hole is for an all-in-one tank, and you should still backfill it as described. That is why all-in-one systems are popular; they don't require all the work and are hard to screw up.
If someone tells you they are going to dig one hole and put the tanks in at the same time, they don't know what they are doing. A lot of installers might not agree but after all the repairs we do on systems that are done like this, we know it to be true. Another problem with doing it like this; you can't get a proper grade as each tank should be a little lower than the next. We have seen pipes that come loose, are broken, or been broken from the get-go. When you take a bucket of dirt and drop it on top of the pipes, the weight is immense, and it's not designed to take that pressure. Also, leaching fields may not work correctly if done this way.
Your control panel for your septic system should never be in the ground. There are multiple reasons and sound logic for this.
Reason number one: in Texas, you can get a bunch of rain and any panel in the ground will be ruined. Number two involves fire ants; they are abundant in southern states. They love electricity and will make their mound around your control panel, get inside, and destroy it. Also putting it on the ground makes it harder to work on and repair. We never mount control panels in the ground. In should be a rule in southern states but we have idiots in Austin. In northern states, you have snow, so it's always best to mount them on a 4x6 piece of treated lumber or to the house. Manufacturers started this because installers are lazy and don't think ahead.
Your junction box, if you have a pump tank, always needs to be on the outside of the tank and not inside or buried underground. This is possibly done by the installer, so wires are not in the open, or they just don't know what they are doing. Guess what? It's a bad idea because the pump or float switch will fail one day, the tank will fill up, and the electricity is underwater. On top of that, the environment of the aerobic septic system is corrosive; it degrades and eats at the copper. So if the junction box is in the tank, you can't get to the wires. It also makes it harder to work on because space is limited in that area of the aerobic septic system. You want the junction box or LB that what we use to be on top of the pump tank riser. This makes life easier on everyone later down the road.
The pump connection should have a union and it should be no lower than 9-15 inches from the top of the riser. This way, if the system does flood, you can get a pair of channel locks in the tank and get the pump undone and out of the tank. If the union is two feet down it makes it difficult as you won't be able to see the pump union if its full of water and you don't want to have to stick your arms in that far to pull the pump.
Installing the Leaching Field
These factors will determine the size of your leaching field:
• The size of your septic tanks
• The type and absorptive capacity of your soil
• The particular technology that you've chosen to absorb the wastewater. This is very important as not enough field lines, and you will get pooling on the ground. If you can afford to put in an extra 50-100, do it. The systems used to install fields lines now are easy, and the technology has really improved the reliability of them.