| Business | Phone |
| A C Engineering Inc 8811 Sudley Rd, Manassas 20110 | (703) 368-5078 |
| William H Gordon Assoc Inc 12204 Dumfries Rd, Manassas 20112 | (703) 580-0409 |
| Oberon Associates 9700 Capital Ct 301, Manassas 20110 | (703) 365-8801 |
| Mullen Engineering Manassas 20110 | (703) 330-0407 |