Redwood City Excavation and Grading Contractor
A Redwood City address doesn’t tell you whose rules your project falls under. Emerald Lake Hills and some other pockets with Redwood City mailing addresses are unincorporated, so grading and tree permits there go through San Mateo County instead. The ground changes just as much, from the former marshland under Redwood Shores to the sloped lots in the hills.
Harris Excavation handles excavation, grading, trenching and drainage across Redwood City for homeowners, contractors and developers. We’re a licensed general engineering contractor (CSLB #1117960) based in South San Francisco, and we confirm which agency’s rules apply before we price the job.
What We Dig in Redwood City
- Foundation excavation for new homes, additions and rebuilds. Residential excavation
- Hillside cuts and retaining wall backfill on sloped lots in the hills
- Drainage fixes such as French drains, catch basins, dry wells and regrading for yards that pond. Residential drainage
- Utility trenching for water, sewer, storm and electrical lines, including PG&E service upgrades and EV charger conduit. We’re PG&E Operator Qualified. Residential trenching
- Site prep and ADU pads cut to grade and compacted to the geotechnical engineer’s spec
- Erosion and sediment control that keeps soil out of the street and storm drains. Erosion control
City or County? Check Before You Dig
Inside city limits, Redwood City’s grading rules send grading permits to the City Engineer. The city treats a job as “engineered grading” if it includes an excavation more than 2 feet deep, a cut slope over 5 feet high, fill over 3 feet high, fill on natural ground steeper than 20 percent, fill that supports a structure, or more than 50 cubic yards of material.
In unincorporated areas like Emerald Lake Hills, San Mateo County’s grading regulations apply. A dig under 2 feet deep that removes less than 150 cubic yards from stable, gently sloped ground can be exempt. The County treats October 15 to April 15 as the heavy-rain season and can refuse land disturbance then if it would cause excessive erosion. On a hillside lot, plan to move dirt in the dry months.
Redwood Shores: Building on Former Marsh
Redwood Shores was built on former San Francisco Bay marshland and is protected by a system of levees. In 2010 the city raised more than three miles of levee around it to meet FEMA standards. In 2020, FEMA warned that without more levee work, about 4,700 households would land in a Special Flood Hazard Area.
Ground like this is often soft and slow to drain. We read the geotechnical report and plan for water before the excavation opens. Our guide to Bay Area soil types explains why Bay mud behaves the way it does.
Redwood City’s 12-Inch Tree Rule
Redwood City has protected trees on private property since 1970. A tree with a trunk over 38 inches around (about 12 inches in diameter), measured between 6 and 36 inches above the ground, needs a city permit to prune or remove. That catches a lot of ordinary backyard trees. Most trees between the sidewalk and curb are city-owned street trees and need a permit too.
In Emerald Lake Hills the County’s threshold is lower. A significant tree there is 19 inches in circumference at 4.5 feet up, half the 38 inches used elsewhere in unincorporated San Mateo County. When a trench or footing passes close to a protected tree, we bring in the arborist early and dig by hand or with a hydrovac truck around roots and live utilities.
Nearby Project: Drainage and Grading in San Mateo
In March 2026 we wrapped up a grading and drainage job just up the Peninsula in San Mateo: 150 linear feet of perforated drain pipe, 200 linear feet of solid drain pipe, 20 tons of material hauled off, and 20 tons of new aggregate base spread by hand for a new parking pad. Flat Redwood City lots that pond in winter often need the same mix. See the project.
Redwood City Neighborhoods We Serve
We work throughout Redwood City, including Mount Carmel, Farm Hill, Eagle Hill, Woodside Plaza, Roosevelt, Palm Park, Downtown and Redwood Shores, plus unincorporated Emerald Lake Hills. Nearby, we also serve Menlo Park, San Mateo, San Carlos, Atherton and Woodside. See all our San Mateo County service areas.
Redwood City Excavation FAQ
My address says Redwood City. Whose permits do I need?
It depends on whether your parcel is inside city limits or in unincorporated San Mateo County, like Emerald Lake Hills. The rules differ, so we confirm the jurisdiction before we price the work.
Does the tree in my backyard count as protected?
In the city, yes if the trunk is over 38 inches around. In Emerald Lake Hills, the County threshold is 19 inches. If one is near the work, bring in an arborist before the dig.
Do I need a grading permit to level part of my yard?
Maybe not. In the city, isolated grading under 50 cubic yards is generally exempt unless it counts as engineered grading, such as a dig deeper than 2 feet. We’ll tell you where you likely stand.
Do you work directly with homeowners?
Yes. We work directly for homeowners and as the excavation subcontractor for general contractors and developers.
Start Your Redwood City Project
Send your address, plans and any soils or arborist report. We’ll confirm whose rules apply, walk the site and send a clear written estimate. Request a free estimate