ADU Surveys in Hercules, CA

Hercules runs a two-desk ADU process: planning approval comes from the city, but building permits and inspections run through Contra Costa County, which provides building services to Hercules. That handoff matters, because it imports the county's submittal framework — site plans with property lines and dimensions, easements, water and sewer line locations for detached units, and trees over 20 inches in circumference within 50 feet of construction — along with the county's geotechnical trigger: a report may be required where the site slopes more than 5 percent, one foot of fall across the ADU footprint, with exemptions only on gentler, trouble-free ground. The city's own guidance notes that even pre-approved plans still need site-specific plans, foundation details, and a geotechnical report if required.

Hercules wears its history in its parcels. The old company town of the Hercules Powder Works left a small historic core near the waterfront, while most of the city's housing came in planned phases from the 1970s onward — the Birds neighborhoods, Refugio Valley's slopes, and the newer transit-village blocks near the shoreline. The planned tracts have recent, recoverable lot corners, making boundary verification efficient; the sloped streets around Refugio Valley Park are where the county's 5-percent trigger earns attention, since a modest backyard grade crosses it easily. Refugio Creek's corridor adds setback and drainage considerations for adjacent lots. Our laser-scanned site survey resolves boundary, structures, trees at the county's circumference threshold, utility locations, and slope in one visit — and where the inspector requires verification that foundation forms match the approved setbacks before the pour, the same boundary work supports the certification in a short return trip.

Records run through the Contra Costa County Recorder in Martinez. Deliverables are a stamped base map, layered DWG, and staked corners; for terrain-led questions see our Hercules topographic surveys.