Topographic Surveys in Petaluma, CA

Petaluma's terrain is deceptively demanding. Through the middle of town the Petaluma River and its tributary creeks define a broad floodplain where the total fall across a lot can be measured in inches, and the difference between a drainage design that works and one that ponds is decided at the hundredth of a foot. Away from the water the ground tilts: the old west-side grid climbs off the flat onto the firm ground that carried downtown through 1906, and the newer east-side subdivisions run up against rolling hills at the edge of the urban growth boundary. The city's own subdivision code recognizes that split. Municipal Code 20.16.150 calls for contours at 1-foot intervals where the predominant ground slope is between level and 5 percent, and 5-foot contours above that, referenced to the city datum, and the tentative map checklist requires that the closest City benchmark be used and its elevation called out on the map.

A conventional total-station topo produces a few hundred shots and interpolates everything between them. On a nearly level Petaluma lot that interpolation is the error. Our Trimble terrestrial laser scanner records millions of survey-grade points in a single visit, so every crown, swale, back-pitched driveway, curb flow line, and top-of-bank is measured rather than assumed. On the dairy ranches and rural parcels beyond the growth boundary the same instrument covers acres of pasture, ranch roads, and creek banks in hours, and we filter vegetation out of the cloud to extract a bare-earth surface beneath oaks and tall grass. Because the whole site lives in the point cloud, a shot your civil engineer asks for two weeks later comes out of the office rather than out of a return trip.

Deliverables are contours at the interval your submittal needs, spot elevations, a DTM, a layered DWG/DXF base map, and NAVD88 elevations for flood-related work, with the registered point cloud available to the design team. Survey filings run through the Sonoma County Surveyor at Permit Sonoma and the Clerk-Recorder in Santa Rosa. When the same site has to feed a land division, see our Petaluma parcel maps.