| Business | Phone |
| Castle Design Group 300 W Patrick St, Frederick 21701 | (301) 668-0505 |
| Charles P Johnson & Assoc 129 W Patrick St, Frederick 21701 | (301) 607-0047 |
| Haller-Blanchard & Assoc 53 E Patrick St, Frederick 21701 | (301) 228-2266 |
| Lavelle & Assoc Inc 1573 Tilco Dr # 1, Frederick 21704 | (301) 695-9722 |
| Powell & Assoc Inc 4987 Winchester Blvd # 5, Frederick 21703 | (301) 663-0175 |
| R & L Surveying Co 220 N Market St, Frederick 21701 | (301) 698-9377 |
| R K Maddox Surveys 4011 Baker Valley Rd, Frederick 21704 | (301) 279-7725 |
| Seismic Surveys Inc 604 Solarex Ct # 104, Frederick 21703 | (301) 663-6630 |
| Seismic Surveys Inc 7313 Grove Rd, Frederick 21704 | (301) 663-6630 |
| Zenith Surveys 200 Dill Ave, Frederick 21701 | (301) 695-5594 |