| # | Company name | Role | # of projects |
|---|---|---|---|
| 201 | Terracon | Geotechnical engineering | 1 |
| 202 | Terracon | Geotechnical engineering | 1 |
| 203 | Terracon | Geotechnical engineering | 2 |
| 204 | Terraprobe Ltd. | Geotechnical engineering | 2 |
| 205 | Terrasol | Geotechnical engineering | 2 |
| 206 | Test Lab, Inc. | Geotechnical engineering | 2 |
| 207 | The Geotechnical Group | Geotechnical engineering | 1 |
| 208 | Thelen Associates | Geotechnical engineering | 1 |
| 209 | Thompson Engineering | Geotechnical engineering | 6 |
| 210 | Tolunay-Wong | Geotechnical engineering | 1 |
| 211 | Treadwell & Rollo | Geotechnical engineering | 6 |
| 212 | Treadwell & Rollo | Geotechnical engineering | 0 |
| 213 | Treadwell & Rollo | Geotechnical engineering | 0 |
| 214 | Trow Associates Inc. | Geotechnical engineering | 23 |
| 215 | TTL Associates, Inc. | Geotechnical engineering | 1 |
| 216 | Ulrich Engineers, Inc. | Geotechnical engineering | 6 |
| 217 | UMA Engineering Ltd. | Geotechnical engineering | 1 |
| 218 | Universal Engineering Sciences, Inc. | Geotechnical engineering | 28 |
| 219 | Van Beveren & Butelo, Inc. | Geotechnical engineering | 1 |
| 220 | Van Elle Ltd. | Geotechnical engineering | 1 |