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Flood QC

Pulls the live FEMA National Flood Hazard Layer zones intersecting the checked area: in the drawing's own State Plane coordinates, labels each zone with its published BFE, optionally draws the boundaries, and checks every VDCGRADELOTS pad elevation against BFE + freeboard.

Command VDCFLOODQC · VDC QC tab › Design QC panel
Pulls the live FEMA National Flood Hazard Layer zones intersecting the checked area: in the drawing's own State Plane coordinates, labels each zone with its published BFE, optionally draws the boundaries, and checks every VDCGRADELOTS pad elevation against BFE + freeboard.
FEMA NFHL zone + BFE queried live; each stamped pad checked vs BFE + freeboard. ZONE AE BFE 12.0 FLOODWAY 1% SFHA boundary (C-FLOOD-ZONE) LOT 1 PAD ERROR: in floodway LOT 2 PAD 12.4 ERROR: < BFE+FB 13.0 LOT 3 PAD 13.6 PASS: clears 13.0 LOT 4 PAD 15.1 Zone X, out of SFHA BFE 12.0 + freeboard 1.0 required pad = 13.0 ft (NAVD88) pad EL read live off the VDCGRADELOTS FL
SFHA / zone boundary C-FLOOD-ZONE   Regulatory floodway   Pad ERROR   Pad clears BFE+FB   BFE + freeboard

What it does

  • Live query: builds an envelope from the checked area, a picked Window by default (the safe choice; running Extents county-wide once crashed Civil 3D, so it stays the default), with Extents available but slow on a big drawing and refusing an empty or absurdly large extent, sent up in the drawing spatial reference; FEMA NFHL geometry returns in modelspace coordinates.
  • Labels: MText per zone at its visible center (ZONE AE / BFE 12.0), background mask on, stamped with VDC_FLOODQC XData.
  • Pad check: reads VDC_AUTOGRADELOTS stamps (same reader as VDCPADLABEL), pad elevation read live off the pad feature line, point-in-polygon vs each zone.
  • Findings: floodway pad = ERROR (no-rise); pad < BFE + freeboard = ERROR; Zone A / no static BFE = WARNING; V zone = WARNING.
  • Refresh: Run wipes its prior flood output first, so it doubles as the re-run after every regrade.

Settings & outputs

  • Spatial reference: any NAD83 State Plane zone (262 listed); any WKID typable.
  • SFHA only (default on), 1%-annual-chance zones; uncheck to also pull shaded X (0.2%).
  • Check pads / freeboard, required clearance above BFE, default 1.0 ft; BFEs are NAVD88.
  • Label zones / draw boundaries, boundaries off by default (flood polygons are large geometry).
  • Flood layer C-FLOOD-ZONE (auto-created ACI 150); every zone gets an INFO row in the CSV in the drawing's VDC Reports folder plus the findings palette.
  • Clear mode erases only the XData-stamped labels and boundaries; settings at %APPDATA%\VDC\FloodQc\settings.json.

Dialog

Flood QC dialog
Flood QC, VDCFLOODQC

When to use it

  • Laying out or grading lots near mapped flood zones - catch a low pad before it's a review comment.
  • After a regrade, to re-verify every pad still clears BFE + freeboard.
  • Building a flood exhibit: zone labels (and optional boundaries) straight from the current NFHL.

How to run it

  1. Run VDCFLOODQC - pick Run in the mode dialog, then set the spatial reference (any NAD83 State Plane zone), freeboard, and output options; click OK.
  2. Choose the area at the [Window/Extents] prompt - Window (two corners) is the default and the safe choice; Extents is available but queries FEMA over the whole envelope, which is slow on a large drawing (an empty or absurdly large extent is refused).
  3. The tool queries FEMA, labels each zone (ZONE AE / BFE 12.0 style), and checks each stamped pad; findings land in the palette (double-click to zoom) and a CSV in the drawing's VDC Reports folder.
  4. Re-run any time - Run wipes its previous labels first. Clear mode removes all flood output.

Options

  • Drawing spatial reference: any NAD83 State Plane zone - 2273 SC intl ft, 102733 SC US ft (Civil's SC83F), 2264 NC US ft, and every other state's; any WKID can be typed.
  • SFHA only: on by default - 1%-annual-chance zones; uncheck to also pull the shaded X (0.2%) zones.
  • Freeboard above BFE (ft): required clearance above BFE (default 1.0; jurisdiction-dependent).
  • Label zones: MText per zone at its visible center, on the flood label layer.
  • Draw zone boundaries: off by default - closed polylines around each zone, on their OWN layer (default C-FLOOD-ZONE-BNDY) so the linework can be frozen, colored, or plotted separately from the labels.
  • Clip boundaries to the checked area: on by default. FEMA returns whole zone features that touch your checked area, not the part inside it - a coastal AE zone can arrive miles wide. Clipping trims each zone to the area you checked; uncheck it to get the whole published polygon.

Watch out for

  • Network required - zones and BFEs come live from FEMA at run time; the service can be slow (30 s timeout).
  • BFEs are NAVD88 feet - the regional drawing datum. A project on an older local datum must convert before trusting the comparison.
  • Zone A (and some AE reaches) publish no static BFE - those pads flag as WARNINGS; read the BFE off the FIRM/FIS profile.
  • This is a QC screen, not a flood study - the FIRM governs. Boundaries are thinned ~1 ft server-side; don't treat them as survey-grade zone lines.
  • A clipped boundary ends at your checked area, not at the zone's real edge - the cut edges are your check area, NOT flood limits. Uncheck clipping when the exhibit needs the whole published zone.

Related: Auto-Grade Lots · Pad Label · Surface QC