Connecticut Boring Logs & Geotechnical Data
2,914 public boring logs in Connecticut; 2,685 with digitized SPT, soil or CPT data; 229 scanned log PDFs. Sources include Connecticut DOT (CTDOT), plus public reports found by web crawl. Free to search on the map, download or query by API.
Where the data comes from
Web-crawled reports in Connecticut were published on, among others: biznet.ct.gov, portal.ct.gov, naugatuck-ct.gov, semspub.epa.gov, norwalkct.gov, easthaddam.org.
Counties with the most boring logs
| County | Boring logs | |
|---|---|---|
| Capitol | 826 | view on map |
| Western Connecticut | 501 | view on map |
| South Central Connecticut | 460 | view on map |
| Naugatuck Valley | 283 | view on map |
| Southeastern Connecticut | 248 | view on map |
| Greater Bridgeport | 211 | view on map |
| Lower Connecticut River Valley | 172 | view on map |
| Northeastern Connecticut | 133 | view on map |
| Northwest Hills | 80 | view on map |
What's in a boring log from Connecticut
The 2,685 digitized borings carry the data engineers actually use: SPT blow counts (N-values) by depth, soil and rock descriptions, groundwater observations and, where the source ran cone penetration tests, CPT tip resistance and sleeve friction. A further 229 logs are scanned PDF reports — the original agency drawings — which you can open and download from the map. Holes are typically about 14 ft (4 m) deep; one in twenty goes past 55 ft (17 m). Not sure what a boring log looks like? See annotated example boring logs.
How to get this data
- Map — pan to a site, click a boring, and view the log, the original PDF, or an ML soil-profile prediction. No account needed.
- Downloads — every boring exports as PDF, DIGGS XML or AGS4; draw a polygon on the map for a multi-boring export or a site report.
- API — query borings by coordinates or bounding box, pull SPT/CPT/lab records, and generate site reports programmatically.
- Contribute — have Connecticut boring logs that are not here yet? We take PDFs, DIGGS, AGS and spreadsheets.
This data was collected from public agencies and is republished as-is. It is a planning tool, not a substitute for a site investigation; see the terms and disclaimer. Counts refreshed 13 October 2026.
Other places
Washington (199,045)Florida (172,401)North Carolina (102,530)Ohio (80,932)Oregon (73,397)California (58,907) all regions →