Soil Sampling Planning Tool

The problem

Planning sampling at a large, long-running Superfund investigation means holding a lot in your head: where samples were already taken, what they found, where the gaps are, and where the next round should go. Doing that across dozens of current and historical locations — on a laptop in the field, without a GIS analyst on call — is slow and easy to get wrong.

What I built

A self-contained web map (no server, just an HTML file) that loads the current and historical sample data and lets the team:

• visualize current and historical sample locations together;
• color-code contamination by analyte (mercury, arsenic, antimony, thallium) against cleanup thresholds;
• run a data-gap analysis with an adjustable grid overlay;
• drop proposed and step-out sample points and export the plan to CSV.

How I solved a piece of it

Color-coding is the fastest way to read a map at a glance, so the tool re-classifies every marker against the relevant cleanup threshold whenever you switch analytes — green / amber / red against the limit for that metal — then repaints the map.

Outcome

The team can plan a sampling round visually in minutes, share it as a CSV, and walk into the field knowing exactly where the gaps are — instead of reconstructing it from spreadsheets.

document.getElementById('colorBySelect').addEventListener('change', function (e) {
  const analyte = e.target.value;
  samples2025.forEach(function (sample) {
    if (sample.sampled && sample.metals[analyte]) {
      const value = sample.metals[analyte];
      const rodLimit = (analyte === 'Mercury') ? 204 :
                       (analyte === 'Arsenic') ? 6.1 : 51;
      sample.color = (value > rodLimit) ? '#d63e2a' :
                     (value > 35) ? '#f0932b' : '#72af26';
    }
  });
  updateMapMarkers();
});