Digging A Drainage Trench 101: An Expert’s Guide


It is horrible to see your plants die and go rotten in your yard. A flooded garden or yard can cause serious damage to your home.

Inadequate drainage systems can lead to yard flooding. It is best to avoid or fix this problem by digging a drainage trench that drains water away from your home and your neighbor’s property.

A french drain, or drainage trench, is a perforated pipe that distributes water flow evenly so as to prevent flooding. It eliminates the leak-and-erosion-causing traditional pipe end.

We are your drainage experts and will discuss our recommendations and tips for digging a french drain. Continue reading

Plan Your Trench Drain

Prior to digging your trench, plan the layout. The following should be determined:

  • Surface water collecting in your yard
  • Any excess water that comes to your yard
  • A place where your water can be directed to prevent any damage

Discuss your drain plans with a professional trencher.

Which direction Of Flow

To determine which areas allow water to flow towards your home, examine your yard’s grading. These are the areas you will need to close to divert water to avoid damaging properties.

At least one inch must be sloped downwards for every ten feet of trench length. The pipe will not drain if it does not have sufficient slope to allow for drainage.

Dig The Trench

Dig a trench large enough to hold gravel and a standard-sized drainpipe. Recommended dimensions are 9-12 inches wide and 18 inches deep.

Tip: Larger trenches are easier to collect water and last longer because they have less clogging.

The soil should be deeper and more firm to allow for better water flow to the perforated drain pipe.

Place Landscape Fabric And Pour With Gravel

To prevent roots and grass infiltration, line your trench with water-permeable landscaping fabric. This will also help to avoid any potential problems in your drainage ditches or pipes.

Make sure you overlap seams and allow extra time to wrap the gravel after digging.

Place at least 2 inches of washed aggregate in your trench, above the landscape fabric liner.

A good amount of gravel can improve your drainage.

Install Your Drain Gate And Drain Pipe

To allow water to flow through your drainage trench, install a drain gate above the trench.

The pipe should be installed near a gutter downspout or flood-prone area in order to direct rainwater to the trench. Your goal is to prevent flooding and divert water through the drainage trench.

Two common pipes are used to drain trenches

Perforated Pipe

This pipe distributes underground water evenly throughout the trench, without leaving a mess at the drain end.

Solid Pipe

A solid pipe, unlike a perforated pipe, transports water to an open-drain, unobstructed end. It should drain into a gravel bed, rain garden, or other ponds that are not susceptible to flooding from a neighboring property.

Cover your drain pipe with gravel to ensure optimal drainage.

Your preference can dictate how you cover your trench. These are our suggestions:

  • Add gravel to it
  • You can line it with bricks and stones
  • It should be covered with soil. Then, plant grass.

FAQS: Digging a French Drain

How deep should a drainage trench be?

To allow gravel and pipes to be installed, a french drain must be at least 18 inches in depth. This allows you to protect and modify the pipe in the future.

Poor drainage can result from a narrow trench. It should be as wide as you can.

How long does it take to dig a trench by hand?

It takes GreenBar Excavation about 12 hours to dig 100 feet of trench. Multiply the length of the trench that you have to dig by 0.12 to calculate the labor hours.

Get your drainage system order in today!

A french drain is a cost-effective and efficient solution to water flooding on your property. It drains large quantities of water away from your property and yard, which can prevent potential damage.

Follow these 10 steps to ensure a better drainage system. To avoid any unwanted damage or headaches, it is a good idea to seek the assistance of drainage and grading professionals.

We can help with your french drain problems!

We offer culvert installation, dozer, and dirt work, as well as other grading or drainage services. Call us today for a quote or to book an appointment.

This post was written by Tanner Brown. Tanner is the Owner and operator of Greenbar Excavation. http://greenbarexcavation.com/ is a fully licensed, insured, and accredited Excavation company based in Prineville, Oregon. Greenbar Excavation is one of the top Excavation companies in Central Oregon. Don’t look further, go with the company with your best interest in mind!

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