- To
- Project team
- From
- Daniel P. Colwell
- Date
- October 17, 2026
- Re
- Phase II, Site Reconnaissance: desktop study, site visit and revised boring plan
What is performed
Site Reconnaissance builds a first picture of the ground before any drilling. It has two parts: a desktop study of published maps and records, and a visit to the site to see conditions, access and hazards in person. Together they produce an anticipated subsurface profile and a boring plan that targets the conditions that matter.
How it is performed
- Desktop study. Review topographic and geologic maps, NRCS SSURGO soil survey units, FEMA NFHL flood zones, state water-well logs and estimated depth to bedrock.
- Historical record. Look at aerial and historical imagery, past slope movements, washouts, slow orders, ballast and drainage maintenance, and culvert and bridge inspection reports.
- Walk the site. Look for tension cracks, seeps and wet areas, bulging or over-steepened slopes, leaning poles and fences, ballast pockets, erosion at culverts and scour at bridges. Take photos with GPS locations.
- Check access. Confirm where a rig can set up, which rig is needed (truck, track-mounted, ATV or hi-rail), overhead and buried utilities, and clearances to the track.
- Revise the plan. Move borings to where the risks are, add borings or test pits where conditions change, and write a short reconnaissance memo with the photo log.
Why it matters in the workflow
Reconnaissance points the exploration at the right targets. A boring placed by reading the ground first tells you far more than one placed on a uniform grid, and seeing access and hazards ahead of time keeps the drill crew safe and productive. The anticipated profile also gives the field engineer something to compare against, so a surprise in the borehole is recognized as a surprise.
What comes in and what goes on
Inputs
- Project record and preliminary exploration plan
- Published maps, imagery and well logs
- Railroad maintenance and inspection history
Passed to Phase III, Subsurface Exploration
- Reconnaissance memo and photo log
- Anticipated subsurface profile
- Revised boring locations and rig selection
- Hazards noted for the safety plan
Use and disclaimers
This phase guidance describes general practice for training and reference. It is not engineering advice for any project. Any value, calculation or report prepared with NANCY must be checked and accepted by a professional engineer licensed in the project jurisdiction, and governing codes, owner standards and the current editions of referenced standards take precedence. NANCY is provided as is, without warranty, and is independent of any employer or client. Use is subject to the full Use and Disclaimers.