French Drain Installation Boise: Process, Timeline & What to Expect

Phase 1: The Initial Inspection (Day 0)

Before any digging starts, we need to understand your property's unique water problems. Our inspection includes:

• Water Source Identification: Is it irrigation runoff? Rising groundwater? Downspout discharge? Neighbor's property? Each requires a different solution.
• Soil Analysis: Boise has wildly varying soil—from loose fill to concrete-like hardpan. This affects excavation difficulty and cost.
• Slope Assessment: We use laser levels to determine the natural grade and plan the drain's path. Water must flow downhill—no exceptions.
• Utility Location: We call Idaho 811 to mark underground utilities. Hitting a gas line is not an option.
• Discharge Planning: Where will the water go? Storm drain? Dry well? Street? We confirm this before digging.

Timeline: Inspection takes 30-60 minutes. We provide a written estimate within 24-48 hours.

Phase 2: Pre-Installation Prep (Day 1 Morning)

Before the crew arrives, you should:

• Clear the work area: Move patio furniture, planters, and anything within 6 feet of the drain path.
• Mark sprinkler heads: We'll avoid them if we know where they are.
• Protect delicate plants: Transplant anything you can't replace.
• Confirm pet arrangements: Dogs and excavation equipment don't mix.

We'll arrive with our equipment—typically a compact excavator (mini-hoe), compactor, and materials trailer.

Phase 3: Excavation (Day 1)

This is the messy part. Here's what happens:

Trenching

We dig a trench along the planned drainage path. Specifications:

• Width: 12-18 inches (enough for pipe and gravel)
• Depth: 18-24 inches for yard drains; deeper for foundation protection
• Slope: Minimum 1% grade (1 inch drop per 8 feet)—verified with laser

Boise-Specific Challenges

Our soil makes excavation harder than in most cities:

• Hardpan: A layer of calcium carbite (caliche) that's nearly as hard as concrete. Common on the Bench.
• Tree Roots: Mature trees in the North End have roots extending 50+ feet.
• Buried Irrigation: Old Boise properties may have abandoned irrigation lines everywhere.

Timeline: A typical 50-foot yard drain takes 2-4 hours to excavate.

Phase 4: Drain Installation (Day 1)

With the trench dug, we install the actual drainage system:

1. 1. Geotextile Fabric: We line the entire trench with non-woven filter fabric. This is the most critical step—it prevents silt from clogging the system. We overlap seams by at least 12 inches.
2. 2. Base Gravel: 2-3 inches of washed 1-inch drain rock goes in first. This creates a bed for the pipe.
3. 3. Perforated Pipe: We use rigid 4-inch PVC with perforations facing DOWN. (Not flexible corrugated pipe—that crushes under soil weight.) Pipes are connected with sealed fittings.
4. 4. More Gravel: Pipe is covered with 6-8 more inches of drain rock.
5. 5. Fabric Wrap: The fabric is wrapped over the top (the "burrito wrap"), completely enclosing the gravel and pipe.
6. 6. Backfill: The trench is filled with the excavated soil, compacted in layers to prevent settling.

Phase 5: Discharge & Finishing (Day 1-2)

The water collected by your drain needs somewhere to go:

Discharge Options

• Daylight Exit: Best option. Pipe emerges on a slope, draining to open ground. Requires adequate yard space.
• Dry Well: Underground pit filled with gravel where water slowly percolates into surrounding soil. Good for flat properties.
• Sump Pump Connection: If you can't drain by gravity, the French drain connects to a sump basin.
• Storm Drain: In some areas, connection to city storm drains is permitted (requires approval).

Final Restoration

We don't leave your yard a disaster zone:

• Soil is graded smooth over the trench
• Sod is replaced if we cut it (optional additional cost)
• Sprinkler repairs are made if we disturbed lines
• All excess material and debris is hauled away

Timeline Summary

What Can Go Wrong (And How We Prevent It)

• Insufficient Slope: Water pools instead of draining. We verify with laser levels, not eyeballing.
• Wrong Fabric: Cheap fabrics clog in 3-5 years. We use commercial-grade non-woven geotextile.
• Crushed Pipe: Corrugated pipe collapses under soil pressure. We use rigid PVC that lasts 50+ years.
• Utility Strikes: We always call 811 and hand-dig near marked lines.