Concrete Pad & Trench for Backup Generator — Langley
Project Overview
A homeowner in the Walnut Grove area of Langley was installing a whole-home backup generator after losing power for three days during a winter storm. The generator manufacturer specified a reinforced concrete pad with specific dimensions and a direct-burial conduit trench running from the pad to the electrical panel on the opposite side of the house. The electrician handled the wiring — we handled everything outside: the pad pour, the trench, the conduit routing, and restoring the lawn afterward.
The Challenge
The generator pad needed to be exactly 42 inches by 72 inches with 4-inch thickness and a minimum of 4 inches of compacted gravel base — manufacturer spec, not optional. The conduit trench ran 45 feet from the pad location to the panel, crossing under a concrete walkway that we couldn't cut. That meant tunneling under the walkway with a boring bar. The trench also had to maintain a minimum 18-inch burial depth per code. After all that digging, the homeowner expected the lawn to look like nothing happened.
Our Solution
We excavated the pad site, compacted a 6-inch gravel base, set forms with rebar on 12-inch centers, and poured 4,000 PSI concrete with a smooth trowel finish and 1-degree slope for water runoff. For the trench, we used a trencher to cut a clean 6-inch-wide by 20-inch-deep channel along the marked route. At the walkway crossing, we used a boring bar to push through without cutting the concrete. Two runs of schedule 40 PVC conduit were laid in the trench on a sand bed. After the electrician pulled wire, we backfilled with the original soil, compacted in lifts, added topsoil, and re-sodded the entire trench line.
Materials Used
- ✓4,000 PSI ready-mix concrete
- ✓Rebar on 12-inch centers
- ✓Compacted gravel base
- ✓Schedule 40 PVC conduit
- ✓Sand bedding for conduit
- ✓Boring bar for walkway crossing
- ✓Kentucky bluegrass sod (trench restoration)
Timeline: 3 days
Project Gallery
The Result
The pad is dead level, the trench is invisible under restored lawn, and the walkway was never touched. The electrician said it was the cleanest generator site prep he'd worked with. Three months later, you'd never know 45 feet of trench was dug across that yard.