How to Dig a Leach Field
A leach field is the part of your sewage system that takes waste water and disperses it into the soil. Using perforated PVC pipes that are laid in trenches within the field, your waste water is absorbed by the soil. Solid waste material remains in your septic tank to be pumped out and disposed of later. The size of your drainage field will depend on the size of the house it is servicing. You can dig a leach field easily with a rented backhoe and have the field dug, the drainage system installed and everything covered within one day. Does this Spark an idea?
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Things You'll Need
- Measuring tape
- Survey stakes
- Hammer
- Orange paint
- Backhoe
- Hand tamp
- Shovel
- Gravel
- Perforated PVC pipe
- PVC pipe 'T' connectors
- PVC pipe glue
- Felt paper
Instructions
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Locate where you want your leach field to be placed. Make sure it is in a location that is below or downhill from the septic tank. A downward slope is necessary to allow gravity to help move the waste water through the pipe and into the leach field. If this is not possible, you need to add a suitably sized dispersal pump to your septic tank in order to move the waste water through the pipe. Consult your local hardware store to find a pump appropriate for your tank's size.
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2
Measure and mark out the size of your leach field using survey stakes and orange marking paint. The size of your house and the type of soil present will determine how large the leach field should be. Use the chart in the resources to determine the size of your leach field. Mark the edges of the field clearly so the backhoe operator will not have a difficulty seeing it from the cab of the machine.
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3
Dig out the entire leach field with a backhoe making the field at least 1-foot deeper then the frost line in that area. The frost line is the average depth that the soil freezes each winter. You will want to place your PVC pipes below this line so they do not freeze and break. You can call your local weather station or research online to find out the depth of the local frost line.
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Spray a line of orange paint on the sides of the field pit that is level to the ground. Measure down and remove dirt as necessary to create a pitched slope to the bottom of the field pit. For example, if your orange line is 6 inches above the bottom of the pit when it was first dug with a flat bottom, you want to remove enough dirt so that it gradually slopes down until the orange line now measures 8 inches above the soil at the farthest end.
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Dig a trench back to your sewage system wide enough to fit the solid PVC pipe that will connect the sewage system with the leach field. Make sure that the depth of this trench falls below the frost line as well and has a slight downward slope from the sewage system to the bottom of the leach field.
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Add 4 inches of gravel to the bottom of the leach field pit and the connecting trench and tamp the gravel until it is compact. You want to maintain the same slope with the gravel that you had with the dirt in both the pit and the trench.
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Make the drain vaults for your leach field out of perforated PVC pipe. Each pipe length can be either 6 or 4 feet long, but all the pieces must measure the same except for the feeder pipe. Lay one pipe across the width of the leach field. Cut and attach 'T' connectors at the following places: in the center (connecting to the solid pipe from the septic tank) and at every 4 foot interval to allow for a drain pipe to be run perpendicular from the feeder pipe and into the leach field. Use PVC glue to hold the pipes in position.
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Lay the drain vault pipe system on top of the gravel in the leach field pit. Connect the feeder pipe to the solid PVC pipe that comes from the septic tank.
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Cover all of the pipe with 6 inches of gravel.
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Lay felt paper over all of the gravel. This will prevent roots from growing down and breaking through or blocking the pipe.
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Backfill the leach field pit and pipe trench with the backhoe using the soil you removed when you dug them out. Fill them until the soil is even with the ground surrounding the trench and pit.
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Tips & Warnings
Dig your leach field larger than what you currently need to service your house. This way, the field will be ready to handle an increase in size should you ever choose to expand your house.
Contact your local utilities companies before digging to make sure there are no buried pipes or wires in that area. Should you dig down and break a line, you could be injured and cause a serious disruption to utility services.
References
Resources
- Photo Credit excavator. image by Stanislav Komogorov from Fotolia.com
