Steep Slope Validator

The Challenge: Why I Built This Tool

If you work in a development services department, you know the “Friday afternoon” scenario: a site plan lands on your desk that is mathematically right on the edge of a Development Permit (DP) trigger.

In my experience, relying solely on GIS contour intervals or LiDAR-derived slope maps often leaves too much room for error. We are frequently forced to make a call: do we trigger a full geotechnical assessment and a geodetic survey, or do we accept the applicant’s desktop analysis?

I developed the Steep Slope Validator to bring transparency and consistency to this exact moment. It is a lightweight, mobile-first utility designed to help planners quickly verify gradients—whether they are at the counter, in the field, or drafting a staff report.

What Makes This Different?

Most online slope calculators are built for hikers or cyclists. This tool is built specifically for Land Use Planning.

  • Transect & Mean Analysis: Choose between a point-to-point cross-section (best for driveways) or a multi-point area average (best for subdivision potential).
  • The “Cautionary Zone”: This is the core of the tool. It automatically flags any result within 5% of your bylaw threshold.
  • Why 5%? Because we know that GIS data has vertical and horizontal tolerances. If a site is sitting at 23% and your trigger is 25%, that is a “Cautionary Zone.” It gives you the professional leverage to request a field-verified survey from a Qualified Professional rather than guessing.
  • Privacy First: No site data is ever uploaded to a server. All calculations happen locally on your device, making it safe for sensitive pre-application discussions.

How to Use the Validator

  1. Select Your Method: Use “Single Transect” for specific building footprints or “Area Average” for complex topography.
  2. Input Geodetic Data: Enter your vertical rise and horizontal run (works with both metric and imperial, as the ratio is universal).
  3. Set Your Threshold: Manually enter your local government’s bylaw limit (e.g., 25% or 30%).
  4. Analyze the Output: The tool will provide a color-coded status—Green (Below Threshold), Orange (Cautionary Zone), or Red (Threshold Exceeded).
  5. Export for File: Use the “Generate PDF” button to save a clean, professional report for your property file or to send back to the applicant.