Basements and Palo Alto’s Dewatering Rules

In many Palo Alto neighborhoods the groundwater is close enough to the surface that a basement dig will hit it. To limit how much pumped water goes to waste, the city only allows construction dewatering from April 1 through October 31. It requires a dewatering plan and a geotechnical study reviewed by Public Works before pumping starts, limits how far below the slab the water can be drawn down, and requires a fill station so neighbors can use the pumped water.

For your schedule, that means a basement that needs dewatering has to be excavated inside that window. We coordinate with your geotechnical engineer and dewatering contractor to sequence the dig, shoring and slab, so the hole isn’t open and pumping any longer than it has to be.

Working Inside Tree Protection Zones

Palo Alto sets a protection zone around protected trees of ten times the trunk diameter or ten feet, whichever is greater. Inside that zone, the city’s tree protection instructions call for air-spade excavation, with hand digging as the backup. Roots 2 inches and larger stay intact, and the project arborist supervises on site. Separately, any excavation or paving within 10 feet of a street tree needs the city arborist’s approval.

We’ve done this work in Palo Alto. On one residential job, our crew hand-dug 150 linear feet of trench, 3 feet deep and 18 inches wide, through hard clay over four days to expose a tree’s root system without damaging it. That gave the arborist what was needed to design around the roots, and the job came in on budget. Read the project write-up.

Grading, Drainage and Street Work

Palo Alto asks new homes for a stamped grading and drainage plan, with the ground sloping at least 2% away from the foundation and neighboring properties. We build the grade to the plan and check it as we go, so final inspection holds no surprises. Our guide to property grading and what it costs explains the process.

If your project puts a trench in the street or sidewalk, such as a new sewer lateral or water service, Palo Alto requires a Street Work Permit from Public Works, separate from your building permit. Soil and debris can’t go into gutters or storm drains, so we protect the inlets and keep the street clean.

Palo Alto Neighborhoods We Work In

We work across Palo Alto, including College Terrace, Professorville, Crescent Park, Old Palo Alto, Community Center, Midtown, Barron Park and Charleston Meadows. Nearby, we also serve Menlo Park, Los Altos, Mountain View and Sunnyvale.

Palo Alto Excavation FAQ

When can I dewater for a basement in Palo Alto?

From April 1 through October 31, with a dewatering plan reviewed by Public Works. Plan the excavation start so the full pumping period fits inside that window.

Can you dig near my oak tree?

Yes, with the arborist’s approval and supervision. Inside the protection zone we dig by hand or with vacuum excavation as the arborist directs, and we leave roots 2 inches and larger intact.

Do I need a separate permit to trench in the street?

Yes. Work in the public right-of-way needs a Street Work Permit from Palo Alto Public Works, in addition to your building permit.

Do you work directly with homeowners?

Yes. We work directly for homeowners and as the excavation subcontractor for general contractors and developers.

Get a Palo Alto Excavation Estimate

Send us your plans, soils report and arborist report if you have them. We’ll walk the site and send a clear written estimate. Request a free estimate