Land Surveying
Topographic Surveying
Measured contours, elevations, and site features on one base map, so your whole design team starts from the same ground.
What is a topographic survey?
A topographic survey is a field survey that measures the shape and elevation of the ground and the location of natural and built features on a property, then presents them on a scaled map with contour lines and spot elevations.
Often called a topo survey, it is the base map that site design starts from: engineers set grades and drainage from it, architects place buildings, and utility designers connect new pipes to existing ones. Your city or county building department decides whether a permit needs one; grading and sloped-lot projects often do.
It maps physical conditions, not property lines. When a design must respect lot lines or easements, pair it with a boundary survey on the same survey control.
Deliverables
What's included in a topographic survey
Scope is set for each project and written into the proposal. A design-level topo survey typically covers:
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Contours & elevations
Contours at an interval suited to the terrain, plus spot elevations at high points, low points, and grade breaks.
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Buildings & hardscape
Footprints, finished-floor and threshold elevations, walls, curbs, walks, driveways, and paving.
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Drainage features
Swales, ditches, culverts, and inlets, with rim and invert elevations where structures can be opened.
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Visible utilities
Manholes, valves, meters, vaults, and poles; underground lines from records or a private locate.
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Trees & landscaping
Trees by trunk diameter and type where a local ordinance or the design calls for it.
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Street frontage
Edge of pavement, curb and gutter, sidewalk, and centerline along the frontage.
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Survey control & datum
On-site control points and the benchmark, so design and staking share one reference.
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Digital deliverables
A signed and sealed PDF map, a CAD file (typically DWG) with a 3D surface, and point data.
When do you need a topographic survey?
Order it before design starts, so the first drawings use measured grades, not assumptions.
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Grading and drainage plans
Finished grades and drainage start from existing contours. See grading plans.
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New buildings, additions, and ADUs
Existing grades set floor levels, driveway slopes, and retaining walls on sloped lots.
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Street, sewer, and storm drain work
Gravity pipes connect only when existing rim and invert elevations are known. See improvement plans.
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Septic and stormwater design
Slopes and flow paths drive the layout of leach fields, basins, and pipes.
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Buying or evaluating land
Contours reveal slopes, low spots, and likely earthwork before you buy.
Flood-zone work needs a different document: a FEMA Elevation Certificate, used for floodplain permits and to support a Letter of Map Amendment (LOMA). Under Risk Rating 2.0 it is optional for NFIP flood insurance but may lower the rate. See elevation certificates.
Process
How a topographic survey works
Five steps from first call to final files.
Define the scope
We confirm limits, contour interval, datum, detail, and file formats with you and your designer, and put them in the proposal.
Research the records
We gather recorded maps, benchmark data, and available utility and street improvement plans.
Set survey control
Control points are set and tied to a published benchmark or the datum your agency specifies.
Collect field data
Crews typically measure with GNSS (satellite positioning) receivers and total stations. Large sites may add drone photogrammetry, drone LiDAR, or terrestrial laser scanning, producing a point cloud checked against ground shots.
Map, review, and deliver
Field data becomes a surface model and drawing, reviewed by the licensee in responsible charge and delivered signed and sealed. The same control can later serve construction staking.
California rules
California requirements for topographic surveys
Topographic surveying is licensed work in California. The rules that matter most:
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Bus. & Prof. Code §8726, §6731.1
Done by a licensed surveyor or civil engineer
The Professional Land Surveyors' Act treats determining "the configuration or contour of the earth's surface" as land surveying (§8726); §6731.1 lets licensed civil engineers do topographic work too. The licensee in responsible charge seals the map (§8761 for land surveyors; §6735 for civil engineers).
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Bus. & Prof. Code §8731, §8762
Property lines are boundary work
Showing property lines is boundary surveying, limited to licensed land surveyors and civil engineers licensed before 1982 (§8731). Boundary work that sets monuments or finds conflicts with recorded maps may require a record of survey filed with the county surveyor (§8762).
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California Building Code, Appendix J
Grading plans need existing contours
Appendix J of the 2025 California Building Code applies where a city or county ordinance adopts it, and to residential buildings regulated by the Department of Housing and Community Development, which adopts it as amended. Where it applies, grading plans must show existing and finished contours, including existing grades on adjoining property (§J104.2). Otherwise, local grading ordinances govern.
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NAVD 88 · Pub. Res. Code §8801
A stated datum and coordinate system
Elevations are usually tied to NAVD 88 and positions to the California Coordinate System (Public Resources Code §8801), which already defines its successor, the California Coordinate System of 2022 (CCS2022). The National Geodetic Survey's replacement datums are in beta and not yet official as of September 2026, so every map should name its datum and benchmark.
Requirements vary by city and county. Confirm your agency's contour interval, benchmark, and required map statements before fieldwork.
Sources & references
- Business and Professions Code §8726, Professional Land Surveyors' Act (California Legislative Information)
- Business and Professions Code §6731.1, civil engineering and topographic work (California Legislative Information)
- Public Resources Code §8801, California Coordinate System (including CCS2022) (California Legislative Information)
- 2025 California Building Code, Appendix J: Grading (ICC Digital Codes, free public viewer)
- Release status of the modernized National Spatial Reference System (NOAA National Geodetic Survey)
Last reviewed .
Topographic survey FAQs
Does a topographic survey show property lines?
A topographic survey does not establish property lines; it maps the ground surface, elevations, and physical features. Property lines come from a boundary survey, which relies on deeds, recorded maps, and monuments found in the field. Design projects often order both, so lines and contours share one drawing and one set of survey control.
Who can prepare a topographic survey in California?
A topographic survey in California must be prepared by, or under the responsible charge of, a licensed land surveyor (Business and Professions Code §8726) or a licensed civil engineer (§6731.1). Mapping ground contours is legally land surveying, and the licensee in responsible charge signs and seals the final map.
What contour interval and datum will my survey use?
The contour interval and datum are set for each project. Design surveys commonly use 1-foot contours; flat or drainage-critical sites may need 0.5-foot contours, and steep sites 2-foot or wider. Your city or county may set the interval. Elevations are usually tied to NAVD 88 through a published benchmark named on the map.
Does a topographic survey show underground utilities?
A topographic survey shows surface evidence of utilities, such as manholes, valves, meters, and vaults, plus rim and invert elevations of structures that can be opened. Lines between those points come from utility records or a private locate; only excavation, often called potholing, confirms their exact position and depth.
Can a drone survey replace a ground topographic survey?
Drone photogrammetry can cover part of a topographic survey. It maps large, open areas efficiently but measures the visible surface, including vegetation, and needs ground control and check shots; curbs, structures, and ground under trees still need ground measurements. An FAA Part 107 pilot certificate does not authorize surveying: in California, a drone-derived topographic map must be prepared under a licensed land surveyor or civil engineer.
What affects the cost and schedule of a topographic survey?
The cost and schedule of a topographic survey depend on site size and terrain, vegetation and access, the contour interval and level of detail, whether utility inverts, trees, or a boundary survey are included, and any agency mapping rules. Share the address, what you plan to design, and your agency's requirements; the proposal then sets scope and timing.