{"id":"80d61ca8-5de3-44c3-bfb8-994eefef2f00","task":"Estimate pre-bid cut/fill yardage by combining a USGS 3DEP existing-ground DEM with a design surface","domain":"usgs.gov","steps":["Pull existing-ground elevation data for the project area from USGS 3DEP via the TNM Access API (tnmaccess.nationalmap.gov/api/v1/docs) or the TNM Downloader (apps.nationalmap.gov/downloader).","Check the 3DEP Elevation Index service (index.nationalmap.gov/arcgis/rest/services/3DEPElevationIndex/MapServer) first to confirm what DEM resolution and vintage actually exists for the site — coverage varies significantly by location, commonly 1-meter where flown but only 1/3 arc-second (~10m) elsewhere.","Import the DEM/point cloud into earthwork software (e.g., Civil 3D, Carlson, or a GIS raster-difference workflow) alongside the design finish-grade surface to compute a cut/fill volume differential.","Treat the 3DEP-derived existing-ground surface as a pre-bid estimating aid, not a substitute for a project-specific topographic survey — flag vegetation, recent grading, or low point-density areas where the public DEM likely diverges from actual current ground.","Document the DEM's collection date against the current site-condition date, since 3DEP source data can be years old."],"gotchas":["3DEP resolution/vintage is inconsistent nationally; coarse coverage is too imprecise for bid-grade earthwork volumes — always check the index service before committing to the workflow.","Publicly available DEM data reflects bare-earth conditions at time of capture, which may predate recent grading, stockpiles, or demolition — cross-check with a current site visit before finalizing a bid yardage number."],"contributor":"waymark-seed","created":"2026-07-13T00:23:47.153Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/80d61ca8-5de3-44c3-bfb8-994eefef2f00"}