1. Before visiting: facts, unknowns and questions
Austin reference point: 30.2672, -97.7431. USDA returned map unit 393253 (Ur), Urban land, 0 to 6 percent slopes, survey TX453. This is the mapped unit at a public reference coordinate, not an inspected property.
Queried 2026-10-22T13:48:36.204Z. Survey-area tabular version 28 was established 2026-09-03T15:16:20.347. Global dataset refresh date: Not available from this source. A query today does not mean a soil survey changed today.
Drainage: Not available from this source; hydrologic group D. The source also reports interpretation ratings, but none confirms conditions at a proposed building pad.
The boxes are a printable worksheet; they are not saved. Download the complete dated example and source receipts (JSON). Use the browser print command to retain this checklist.
2. An address is not the center of a parcel
Census calculates coordinates along address ranges; a successful address match is not a surveyed building or parcel center. Our actual public-address example “4600 Silver Hill Road, Suitland, MD 20746” matched 4600 SILVER HILL RD, SUITLAND, MD, 20746 at 38.84505589808, -76.92836638093. Census reported address-range interpolation using Public_AR_Current / Current_Current at 2026-10-22T13:52:03.941Z. A separately chosen map point, for example 38.8460, −76.9274, is a different query point; neither establishes a boundary. The abbreviated street-only address and an intentionally nonexistent example number returned no match, with no substituted location. Before relying on a result, compare the returned matched address and coordinate with the intended public map location.
If an address has no match or an unexpected match, stop and correct the input. Do not substitute another city or a nearby number silently. Census geocoding basics explain the method. Use the coordinate tab when you already know the intended point.
3. One SSURGO unit, four components
Raleigh public reference point 35.7803, -78.6645 returned Chavis-Urban land-Pacolet complex, 2 to 15 percent slopes, map unit 3410847, survey NC183, tabular version 29 established 2026-09-03T13:43:46.863. Queried 2026-10-22T13:49:28.790Z. Its four source components are:
- Chavis: 40% representative share; drainage Well drained; hydrologic group C.
- Urban land: 35% representative share; drainage Not available from this source; hydrologic group Not available from this source.
- Pacolet: 20% representative share; drainage Well drained; hydrologic group B.
- Beltline: 5% representative share; drainage Well drained; hydrologic group C.
Representative percentages describe expected composition of the mapped unit; they do not locate a component beneath this exact point. Low/high ranges and nulls remain in the download. The unit cannot be replaced by its first soil name. Read map units and component shares.
4. Two nearby points, two local slope estimates
- Point 30.2672, -97.7431: 1.06% local slope; nine samples; radius 45 m; source-reported resolution 1 m; queried 2026-10-22T13:48:38.023Z.
- Point 30.2678, -97.7431: 1.64% local slope; nine samples; radius 45 m; source-reported resolution 1 m; queried 2026-10-22T13:48:38.330Z.
The points are about 67 m apart. Each nine-point grid uses opposing east/west and north/south elevations for its central gradient; relief uses all nine values. The raw samples and original response hashes are in the download. Source resolution is not measurement accuracy and query date is not acquisition date. These local estimates omit retaining walls, drains and recent modifications; they are not a grading or drainage plan. Read the slope method.
5. A map does not approve a septic system
Drainage class, hydrologic group and a mapped septic interpretation are survey context. They are not a site-specific perc test, a system design or a permit. Ask the local permitting authority which evaluation, setback, groundwater and design documents apply to the actual proposed area. Do not turn a general map rating into approval or denial of an individual site.
EPA septic systems questions and permitting · USDA SSURGO scope.
6. Incomplete report: how to continue
The Austin response really omits drainage class and several component attributes; those are preserved as null, not zero or an estimate. In contrast, the downloadable controlled failure examples deliberately set soil or terrain unavailable to illustrate an outage. They are simulations, not observed outages at these coordinates.
- A null field in a successful profile means the source did not supply a usable value.
- No mapped soil unit is a coverage/result condition.
- A provider error is an unavailable result; retry later or consult its official tool.
- An unmatched address must be corrected or replaced with an explicitly chosen point.
USDA Web Soil Survey · USGS National Map. Keep the same intended location and record which provider supplied each later answer. An incomplete report does not establish construction suitability.