Underground
Utility Services

811 is California's "Call Before You Dig" service. Before any excavation or trenching begins — regardless of depth — California law requires contacting 811 at least two business days in advance. The utility companies then send locators to mark the approximate location of their underground lines with colored flags or paint.

This step isn't optional and isn't just a formality. Hitting an unmarked underground utility line can cause serious injury, service outages affecting an entire neighborhood, and significant liability for the property owner and contractor. We always call 811 and wait for utility marks before opening any trench. If you're planning utility work and a contractor doesn't mention 811, that's a problem.

In most cases, yes. Installing or replacing a water service line, sewer lateral, electrical service, or gas line typically requires a permit from the local building department and coordination with the relevant utility company. The permit triggers inspections at key stages — typically before backfill — to verify that the work meets code requirements.

The specific requirements vary by county and municipality. Sonoma County and Monterey County have their own permit offices, and incorporated cities within each county may have additional requirements. We're familiar with what's required in the areas we work and can help identify what permits apply to your project.

Minimum burial depth varies by utility type and is governed by California Building Code and applicable utility company standards. As general guidance: water lines are typically buried at least 18–24 inches deep; sewer lines depend on the slope required for gravity flow and are often deeper; electrical conduit depth varies based on whether it's in a conduit sleeve or direct-buried cable; gas lines are typically 18–24 inches minimum.

These are minimums — actual installation depth may need to be greater based on freeze protection requirements, soil conditions, or crossing under roads and driveways. The permit and inspection process verifies that depth requirements were met before backfill is allowed.

A utility trenching project starts with 811 marking and permit approval. We then excavate the trench to the required depth and width, taking care to avoid any marked existing utilities. The bottom of the trench is prepared with appropriate bedding material — typically sand or crushed aggregate — before the pipe or conduit is laid.

Once the pipe is in place, we coordinate the inspection with the building department before backfilling. After inspection, we backfill in lifts and compact to the required density. Any surface restoration — patching paving, regrading, or restoring landscaping — happens last. The total timeline depends on the scope, permit timing, and inspection scheduling.

Trenching through existing landscaping or paved surfaces requires careful planning. We try to route trenches to minimize surface impact where possible, and we take care during excavation to preserve root systems and minimize the affected area.

For paved surfaces, we saw-cut clean edges before excavating so the trench patch has straight, defined boundaries. After backfill and compaction, we restore the paving to match the existing surface as closely as practical. For landscaped areas, we stockpile topsoil separately, restore grade, and compact the subgrade before replacing topsoil. We're realistic with property owners about what restoration looks like — a fresh trench patch never looks exactly like undisturbed pavement, but we do the work correctly so it performs well over time.

A sewer lateral is the private line that runs from your building to the public sewer main in the street. The lateral is typically the property owner's responsibility from the building to the point of connection with the public main. The sewer main is the public infrastructure in the street, maintained by the city or sanitation district.

Lateral replacements are one of the most common underground utility projects we do. Older laterals — particularly clay pipe installations from the mid-20th century — fail through root intrusion, cracking, and joint separation over time. We handle the excavation, removal, and new pipe installation on the private portion of the lateral and coordinate the connection to the public main with the relevant agency.

The excavation and installation work itself on a typical residential utility project — a single water line, sewer lateral, or electrical service — usually takes one to three days of field work. The overall project timeline is often longer because it's driven by permitting and inspection scheduling rather than the excavation itself.

Permit processing time varies by jurisdiction and workload — sometimes a few days, sometimes a few weeks for complex projects. Inspection scheduling adds additional time between trench opening and backfill approval. We try to sequence work to minimize delays and will let you know upfront what the realistic timeline looks like for your specific project and location.

Yes, but it requires planning. Parts of the California Central Coast — particularly the Salinas Valley and other low-lying agricultural areas in Monterey County — have seasonally high water tables that can make trench work challenging. When a trench fills with water, it compromises bedding, makes proper compaction difficult, and creates trench stability issues.

We address high groundwater through trench dewatering — pumping water out of the trench as it fills — and by scheduling work in drier periods where possible. For some situations, trench boxes or shoring may be required for safety. We evaluate site conditions before committing to a timeline and build the right approach into the project plan.

Yes. DW Excavation holds California Contractor License #1060838 and carries the required liability insurance and workers' compensation coverage. We've been performing underground utility work on the California Central Coast since 2013 and are familiar with the permit requirements, inspection processes, and utility company coordination procedures that apply to this work in both Sonoma and Monterey Counties.

Note that while we handle the excavation and trenching side of utility work, licensed specialty contractors (plumbers, electricians) typically handle the actual pipe and wire connections. We coordinate with those trades as part of a complete project, or we work alongside your existing subcontractors as the excavation contractor.

Cost depends on the length and depth of the trench, soil conditions, whether existing pavement or landscaping needs to be removed and restored, permitting fees, and whether there are existing utilities in the path that require extra care. A short water line replacement under a yard is a very different scope from running a new sewer lateral 150 feet through clay soil and existing paving.

We don't publish price ranges because they're too variable to be useful without site context. Call 707-601-9091 and we'll schedule a site visit to understand the specific conditions and give you an accurate estimate.