Proper excavation and backfilling are essential for drainage systems to work effectively. This guide outlines how to prepare trenches with proper slope and how to restore the yard for long-term durability.
Excavation
Set slope with precision: Use a laser level and grade rod or a 4' stick level to ensure a minimum slope of 1% throughout the trench.
Check depth requirements: Depending on the project, ensure the trench depth is at least 12", 14", or 18" minimum.
Dig the rough trench: The excavator should dig the basic trench path, staying within depth and slope targets.
Smooth and prep the trench floor: A person inside the trench should level the base by removing humps with a shovel and fixing low spots by adding compacted dirt.
Keep the sides clean: Maintain clean trench walls and ensure excavated dirt is placed on one side—preferably on plywood sheets to minimize yard damage.
Hand dig near utilities: Especially around gas lines and other sensitive areas, switch to hand tools for safety.
Backfill
Inspect trench before backfill: Ensure it's clean—no tools, trash, loose materials, or debris (like tree limbs) left inside.
Backfill with excavator: Use the bucket to push dirt from plywood or piles into the trench in controlled amounts.
Hand backfill sensitive spots: Around downspouts, catch basins, and other delicate areas, use shovels for better control.
Use a hard rake if needed: For clumpy soil or uneven distribution, use a hard rake and excavator bucket teeth to pull dirt into the trench area and smooth the surrounding yard.
Compact thoroughly: Drive the excavator over the trench at least 6–10 times (or more for clay soils) to compress the backfill and reduce future settling.
Leave a mound: Leave a 2–3" mound above the trench. As the soil settles over the next 6 months, this will result in a flat, level yard for the client.