Inventory and Analysis
What to know
Inventory and analysis begins with accurate base information. Know survey types-boundary, topographic, and ALTA-and the difference between contour interval and index contour. Identify natural resources: soils and percolation, hydric soils, wetlands (three-parameter delineation: hydric soils, hydrophytic vegetation, and hydrology), floodplains and floodway, vegetation and tree diameter at breast height (DBH), wildlife habitat, slopes, and drainage patterns. Cultural resources include zoning (setbacks, floor-area ratio, lot coverage, height), easements, utilities, circulation, and adjacent uses. Analysis overlays these data to produce opportunities and constraints, suitability, and site selection conclusions.
Traps
Do not equate visible water with wetland jurisdiction or assume a wetland ends at the water's edge. Floodway (no-rise) differs from flood fringe. Tree protection is based on critical root zone, not just trunk location. Slope is rise over run times 100, not an angle. Zoning calculations must account for both dimensional standards and use permissions; conditional uses are not permitted by right. Check whether the survey datum and benchmark are stated before using elevations.
Worked example
A 24-inch DBH tree has a critical root zone radius commonly calculated as 1 foot per inch DBH: 24 feet. Some jurisdictions require 1.5 feet per inch for sensitive species. A 6-foot rise over a 40-foot run is 15% slope. Overlay mapping rule: inventory first, analyze second, synthesize third.