| Centurum Information Technology, Inc. | Hanahan | SC | $0 |
| Century Engineering, LLC | Hunt Valley | MD | Subcontractor |
| Cerami & Associates, Inc. | New York | NY | Subcontractor |
| Certerra Instrumentation And Monitoring, LLC | Rancho Cucamonga | CA | Subcontractor |
| Certerra Southeast, LLC | North Charleston | SC | Subcontractor |
| Ces Consultants, Inc. | Coral Gables | FL | $0 |
| Ces Group Engineers, LLP | Charlotte | NC | $0 |
| C. Fly Marine Services LLC | Madisonville | LA | $0 |
| CFM Engineering Support Services, LLC | Mount Hope | KS | Subcontractor |
| CFP Engineering, LLC | Crownsville | MD | Subcontractor |
| Cf Technologies, Inc. | Hyde Park | MA | Subcontractor |
| CG2, Inc. | Milpitas | CA | Subcontractor |
| CH2M Hill Inc. | Montgomery | AL | $0 |
| CH2M Hill, Inc. | San Antonio | TX | $0 |
| Chain Ring LLC | Stuart | FL | Subcontractor |
| Champion Engineering Services LLC | Upper Marlboro | MD | $0 |
| Channel Marker Technologies, LLC | Poway | CA | Subcontractor |
| Chapman Technical Group, Limited | Saint Albans | WV | $0 |
| Charles A Clark Jr | Chatsworth | CA | Subcontractor |
| Charles Kircher & Associates | Palo Alto | CA | Subcontractor |
| Charles M Blank | Fountain Hills | AZ | $0 |
| Charles M. Salter Associates, Incorporated | San Francisco | CA | Subcontractor |
| Charles P. Johnson & Associates, Inc. | Silver Spring | MD | Subcontractor |
| Chastain & Associates LLC | Decatur | IL | Subcontractor |
| Chen Moore And Associates, Inc. | Fort Lauderdale | FL | $0 |
| Cherokee Fire Protection Engineering, LLC | Clarksville | TN | Subcontractor |
| Chesapeake Aerospace, LLC | Parkersburg | WV | Subcontractor |
| Cheshir Industries Inc. | Austin | TX | Subcontractor |
| Chew Engineering Inc. | Seymour | MO | Subcontractor |
| Chironix Pty Ltd. | Malaga | WA | $0 |
| Cho Design Associates | Santa Ana | CA | Subcontractor |
| Christopher Maus | Lusby | MD | Subcontractor |
| CHR Solutions, Inc. | Mitchell | SD | $0 |
| Ciani & Hatch Engineering, PLLC | Kenmore | WA | Subcontractor |
| Cibor Inc. | Houston | TX | Subcontractor |
| Cicci David Allen | Auburn | AL | $0 |
| Cintar Inc. | Glenshaw | PA | Subcontractor |
| Citadel Engineering Company (cec) | Salt Lake City | UT | Subcontractor |
| Civil Consultants | South Berwick | ME | $0 |
| Civil Consultants, Inc. | Birmingham | AL | Subcontractor |
| Civil Design & Construction, Inc. | Port Allen | LA | Subcontractor |
| Civil Design Services Inc. | San Antonio | TX | $0 |
| Civil Engineering Professionals, Inc. | Casper | WY | $0 |
| Civil Science Inc. | Lehi | UT | $0 |
| Civil Services, Inc. | Jacksonville | FL | $0 |
| Civiltec Engineering, Inc.Monrovia, CA · UEI J6HKNEPJKJ57 | Monrovia | CA | Subcontractor |
| Civiltec Engineering, Inc.Prescott, AZ · UEI PKQUNHZMW943 | Prescott | AZ | $0 |
| C.j. Brown Energy & Engineering, P.C | Cheektowaga | NY | $0 |
| CJL Engineering, Inc. | Coraopolis | PA | $0 |
| Cj Quinones Engineering, PSC | San Juan | PR | $0 |
| CK3 LLC | Ontario | OR | $0 |
| C-K Associates, LLC | Baton Rouge | LA | $0 |
| CKS Technologies, LLC | Huntsville | AL | Subcontractor |
| Ck Technologies LLC | Meridianville | AL | Subcontractor |
| Clanton Engineering, Inc. | Boulder | CO | Subcontractor |
| Clarke House Technologies, Inc. | North Wildwood | NJ | Subcontractor |
| Clear Aspect Solutions LLC | Hampton | VA | Subcontractor |
| Clearly Engineered LLC | Freehold | NJ | Subcontractor |
| Clearplan LLC | Westborough | MA | Subcontractor |
| Cleary Zimmermann Engineers, LLC | San Antonio | TX | Subcontractor |
| Cleveland Aerospace Technology Servies LLC | Davidsonville | MD | Subcontractor |
| Closedloop Communications Inc. | Fulton | MD | Subcontractor |
| Clough, Harbour & Associates, LLP | Albany | NY | $0 |
| CLP Engineering LLC | Denver | CO | Subcontractor |
| Cma Architects & Engineers LLC | Guaynabo | PR | $0 |
| CMJ Engineering & Testing Inc. | Fort Worth | TX | Subcontractor |
| Coalmont Electrical Development Corporation | Mc Calla | AL | $0 |
| Coastal Science & Engineering, Inc. | Columbia | SC | $0 |
| Coastal Technology Corporation | Vero Beach | FL | Subcontractor |
| Coastline Consulting Services, Inc. | Pooler | GA | Subcontractor |
| Coastwise Fireguard Inc. | Chaska | MN | $0 |
| Coating Specialists And Inspection Services | Tempe | AZ | Subcontractor |
| Cobb Design Inc. | Saint Petersburg | FL | Subcontractor |
| Cobb, Fendley & Associates, Inc. | Houston | TX | Subcontractor |
| Coburn Analytical Services, Inc. | Beavercreek | OH | Subcontractor |
| Codarra Advanced Systems Pty Ltd. | Queanbeyan | NSW | $0 |
| Code Consultants Inc. | Saint Louis | MO | Subcontractor |
| Coffman Engineers Inc.Seattle, WA · UEI QR6ZKKR7SCJ6 | Seattle | WA | Subcontractor |
| Coffman Engineers Inc.Woodland Hills, CA · UEI TX9UUDM7MMH9 | Woodland Hills | CA | Subcontractor |
| Coffman Engineers, Inc.Fulton, MD · UEI FP7KP44EB6L8 | Fulton | MD | Subcontractor |
| Coffman Engineers, Inc.Tamuning, GU · UEI WJN7RP5UNHK6 | Tamuning | GU | Subcontractor |
| Coffman Engineers, Inc.Raleigh, NC · UEI EW9GVEPKLAL7 | Raleigh | NC | Subcontractor |
| Coffman Engineers, Inc.Duluth, GA · UEI YJXVAUUW3FK5 | Duluth | GA | Subcontractor |
| Coffman Engineers. Inc. | Oakland | CA | Subcontractor |
| Cogenia Partners LLC | Petaluma | CA | Subcontractor |
| Cogito Innovations LLC | Hollywood | MD | Subcontractor |
| Cohesionforce Inc. | Huntsville | AL | Subcontractor |
| Cohlmia Engineered Services, LLC | Arvada | CO | Subcontractor |
| Cole & Associates, Inc. | Saint Louis | MO | Subcontractor |
| Cole Marie Austin LLC | Brownsboro | AL | Subcontractor |
| Colin Gordon Associates | Burlingame | CA | Subcontractor |
| Colliers Engineering & Design, Architecture, Landscape Architecture, Surveying, Ct P.C. | Albany | NY | Subcontractor |
| Collinear Group LLC | Renton | WA | Subcontractor |
| Collings & Associates, LLC | Ventura | CA | Subcontractor |
| Collins Alliance Group, LLC | Oxon Hill | MD | Subcontractor |
| Collins Engineers Inc. | Saint Paul | MN | Subcontractor |
| Collins Engineers, Inc. | Hampton | VA | $0 |
| Collins Engineers, Incorporated | West Jordan | UT | Subcontractor |
| Colorado Professional Resources, LLC | Colorado Springs | CO | Subcontractor |
| Columbia Energy & Environmental Services, Inc. | Richland | WA | Subcontractor |
