PG&E Joint Trenches Are Non-Negotiable—Here’s How They Work
A joint trench carries both gas and electric lines in a single excavation with internal barriers separating them. PG&E doesn’t technically mandate joint trenches, but they’ll push back hard on parallel trenches without documented site constraints. I’ve seen projects delayed four months because the developer assumed they could run separate trenches. They can’t, unless you’ve got seismic faults, contaminated soil, a water table above minus-eight feet, or slope angles that physically prevent it. Start your coordination now—before your civil drawings are locked.
Why PG&E Prefers Joint Trenches
PG&E’s preference isn’t arbitrary. Joint trenches reduce installation cost, cut easement requirements, and simplify maintenance access. For us, that means fewer site plan conflicts and faster approvals when we design to their standard. The gas line sits on a shelf or ledge; the electric duct bank runs below or alongside it. Barriers—concrete, plywood, or PVC—keep the two utilities isolated. This separation satisfies California Code of Regulations Title 8 (Cal/OSHA) work safety requirements and PG&E’s own standards.
What developers miss: joint trenches still require separate conduit and separate easement language in your CC&Rs, even though they share one hole. You’ll need easements for both utilities on the same alignment. Don’t combine them into one easement—PG&E’s legal team will reject it.
When Parallel Trenches Are Actually Defensible
Parallel trenches require documented justification. We’ve approved them in three scenarios:
- Seismic fault zones: If your site sits on or crosses a mapped fault (check the State Geological Survey database), PG&E will accept parallel trenches with increased separation—typically 10 feet minimum.
- Contaminated soil: Phase I ESA results showing volatile organics or petroleum above remedial action levels in the trench zone. PG&E requires a certified Phase I and may demand deeper burial or encasement, making joint geometry impossible.
- High water table: Seasonal groundwater at minus-six feet or higher. You’ll need hydrogeologic data. PG&E may accept parallel trenches rather than deal with dewatering complexity in a joint configuration.
- Slope constraints: Cuts steeper than 2:1 or fills steeper than 3:1 where joint trench depth would trigger retaining walls. Parallel trenches can sometimes follow contours instead.
Generic reasons—”we don’t have space” or “it’s cheaper”—won’t fly. Have a geotechnical or civil engineer document the constraint in writing before you submit.
The 16-Week Coordination Timeline
Start here: 4.5 months before your planned groundbreaking date. Here’s the real sequence:
- Week 1: Call PG&E’s Developer Services line at 1-800-227-2000. Have your APN, address, project scope, and site plan ready. They’ll assign a project manager and request formal drawings.
- Weeks 2–3: Submit complete site plans with utility corridors, easement locations, and trench depth/width notes to PG&E via their online portal or assigned PM.
- Weeks 4–6: PG&E field review. They’ll mark the site, identify conflicts with existing lines, and assess accessibility. Don’t miss this walk—the PM needs you there to answer questions about grading and building setbacks.
- Weeks 7–9: Design approval. PG&E reviews your trench specs, conduit size, and burial depth against their standards. Expect one revision cycle.
- Weeks 10–12: Permit coordination. Your building permit and PG&E’s utility permit process overlap here. Check with your city—some require PG&E approval before they’ll issue grading permits.
- Week 13+: Construction. PG&E may require a service representative on-site during the first dig; confirm this in advance.
This isn’t negotiable. I’ve never seen it compress below 12 weeks for a standard project. Seismic, contamination, or water-table issues add 4–6 weeks.
Call 811 Before You Dig—No Exceptions
California Government Code Section 4216 mandates a utility locate call 48 hours (but not more than five business days) before any excavation. Call 811 or visit call811.com. This triggers PG&E’s marking crew to flag existing lines in spray paint. Digging without a valid locate ticket costs $1,000+ per violation, kills your insurance coverage, and can kill someone. We’ve seen it shut a project down for a month while the city investigates.
Document the ticket number and crew completion. Your grading contractor needs that confirmation before they roll.
Common Failures We See in the Field
Designers skip the verbal call and jump straight to drawings. PG&E then rejects the entire design because the site doesn’t support their standard. Start the conversation first—it’s 20 minutes and saves weeks.
Contractors assume a locate ticket covers both gas and electric. It doesn’t. Gas lines are often at a different depth. You’ll get electric marked and then hit a gas line at 48 inches below surface. Call 811 early enough that you can request a second crew if needed.
Easement language doesn’t match trench specs. Your attorney writes “utility easement” but the trench is 12 feet wide. PG&E’s title team will reject it. Specify width, depth, and the fact that both gas and electric occupy the same easement footprint.
Water and sewer conflicts go unresolved. Your joint trench design shows PG&E at 36 inches, but the city’s sewer line is already there at 42 inches. That redesign happens six weeks into grading. Coordinate all utilities—water, sewer, storm, telecom, gas, electric—on one cross-section before you finalize the trench layout.
What Your Engineer Needs to Submit
We always include: site plan with utility corridors at 1/16″ scale, trench cross-section showing depth and width (typically 4–6 feet wide, 4–8 feet deep for joint), conduit schedule (PG&E usually specifies 4-inch PVC for gas, 3-inch or 4-inch for electric), burial depth in feet, separation distance if parallel, and easement boundaries. Add a note citing Title 8 Cal/OSHA and PG&E’s current standards. PG&E’s template is on their website—use it.
Get Your Joint Trench Right the First Time
We’ve handled over 80 utility coordination projects in the Bay Area and Central Valley. The ones that sail are the ones that start conversations with PG&E before the pen hits the paper. If you’re breaking ground in six months, call us now. Contact Calichi Design Group to walk through your site and file the right way the first time.