Monument Preservation in Antioch, CA

Antioch is one of Contra Costa County's oldest cities, and its street network tells that story in layers: a historic riverfront downtown on the San Joaquin, broad postwar tracts across the flats, and newer hillside subdivisions to the south. A growth city this size runs continuous capital programs — annual pavement rehabilitation, water and sewer main replacement, and streetscape work in the old downtown — and every one of those projects passes over survey monuments. The downtown blocks are the most sensitive: monuments there may date to Antioch's earliest subdivisions, and they anchor lot lines that predate the modern record system. In the postwar tracts, tract monuments set in the 1950s and 60s still control thousands of residential boundaries, and a citywide overlay program can disturb hundreds of them in a single season.

Business and Professions Code §8771 requires each of those monuments to be referenced by a licensed land surveyor before the work and reset after, with Corner Records filed with the Contra Costa County Surveyor in Martinez at both ends of the process. We handle this at program scale: record research to identify every monument within the year's project limits, field search and referencing before the contractor mobilizes, filings in Martinez, and a resetting campaign once paving is complete. Our Trimble terrestrial laser scanner makes corridor-scale referencing efficient — a downtown streetscape block or a full tract street is captured at survey grade in a single visit, monuments and surrounding improvements together, which also gives the city an as-built-quality record of pre-construction conditions. Along the Delta shoreline and marina margins, where filled ground falls within state Seismic Hazards Mapping Act liquefaction zones, that same dense documentation supports the geotechnical and design work that shoreline projects require.

For Antioch's public-works contractors, the math is consistent: preservation under §8771 costs a small, biddable amount per monument. A destroyed downtown monument, by contrast, can force a boundary retracement through 150 years of records — many times the cost, plus the liability exposure of having violated state law.