Septic holding tanks are a long-term temporary solution for sewage disposal. The tank retains waste until the tank is emptied. Holding tanks must be checked regularly to avoid overflowing waste into the ground surrounding it. The single difference between a permanent septic system and a holding tank is the lack of an outlet on the holding tank.
Obtain any construction permits required per community ordinances. Have the construction site approved along with the plans.
Plan the drain field around the tank. You may need a leaching field for gray water depending on your community ordinances. Should the tank overflow, the field must be far enough away from any water source, wetland or structure to avoid contamination and seepage.
Identify the main sewage line in the house. Locate the exit point of the line from the house. You might need to dig up around the exit point to access the end of the line.
Connect the 10-foot PVC pipe to the end of the line. The PVC pipe should have an adapter ring at one end to attach to the sewer line.
Take a measurement from the base of the tank to the bottom of the inlet pipe. This is the minimum depth the tank must be placed underground. Measure the width of the tank. Add 2 feet to both measurements to find the depth and width of the installation pit.
Measure and mark a line from the end of the drain pipe from the house to the location of the tank pit. Cut a section of PVC pipe matching this distance and add ½ inch.
Dig out the pit using the measurements from the septic tank, remembering to add 2 feet to the depth and width. Pour in a 1-inch layer of pea gravel for the base. Level the base of the pit by hand using the rake and carpenter's level. The tank must be level to keep accurate measurements of the contents.
Lower the tank using a boom truck. Check the accuracy of your measurements and adjust the pit dimensions or base accordingly.
Connect the second PVC pipe to the inlet pipe. Glue the other end of the PVC pipe to the main sewer line.
Flush the toilet several times to check the connections and the tank.
Have the installation approved by the local authorities.
Backfill the hole with dirt until only the hatch at the top of the tank is visible. Seed the area with grass seed.