| Business | Phone |
| Engineered Piping Products Inc 3955 Dartmouth Ct, Frederick 21703 | (301) 874-1113 |
| Lane Enterprises Inc 7340 Executive Way # M, Frederick 21704 | (301) 620-1122 |
| Rinker Materials-Hydro Conduit 1751 Monocacy Blvd, Frederick 21701 | (301) 698-7373 |