Office Administrator Senior

Amentum; Warrenton (VA); On-site; USD 85,000 - 115,000; Full time

Benefits offered by this job

Health, dental, and vision insurance

Paid time off and holidays

Retirement benefits (401(k) matching)

Educational reimbursement

Parental leave

Employee stock purchase plan

Tax-saving options

Disability and life insurance

Pet insurance

Job summary

Amentum seeks a Senior Office Administrator to support a high-security IT program in Warrenton, VA. You will manage front-desk operations, calendars, and onboarding while coordinating travel and visitor access.

The role requires a Top-Secret clearance (SCI) or ability to obtain, 4+ years of office administration, and strong MS Office, communication, and organizational skills in a dynamic team environment.

Qualifications

• Active Top-Secret clearance with SCI or the ability to acquire SCI
• 4+ years of office administration/management experience
• Must be able to work a 40-hour work week, normally Monday through Friday
• Willingness to travel 5-10% primarily within 75 miles
• MS Office applications such as Excel, Word, Outlook, SharePoint, Project and Visio
• Exceptional attention to detail; excellent verbal and written communication skills; strong critical thinking, organizational, time-management, and problem-solving skills

Responsibilities

• Greet and check in all visitors to create a professional and friendly first impression, ensuring they understand entry procedures and program protocols
• Arrange escorts for visitors by coordinating with available staff, confirming clearance requirements, and tracking escort responsibilities throughout the visit
• Answer, screen, and transfer incoming phone calls promptly, providing accurate information and directing callers to the correct personnel or department
• Monitor office supply levels by regularly checking inventory, forecasting needs, and placing timely replenishment orders to prevent shortages
• Coordinate with facility staff for reception area needs, addressing issues like badge access, seating, and general front-office maintenance
• Maintain and update the shared office calendar to ensure complete visibility of program activities, including meetings, deadlines, travel schedules, and team availability. Schedule meetings by reserving rooms, managing attendee lists, and preparing or distributing necessary materials and reminders
• Provide calendar updates to team members and leadership so plans remain aligned and conflicts are identified early. Maintain accurate personnel rosters and ensure updates are made promptly when staffing changes occur
• Create and manage mailing lists, emergency phone trees, and distribution lists used for communication across the program
• Update organizational charts to reflect new hires, role changes, or reporting structure adjustments, ensuring leadership visibility into team composition
• Maintain escort rosters and other administrative lists required for compliance, access control, and operational readiness
• Organize and store all administrative documents according to program standards, ensuring they remain easily accessible and current
• Support onboarding by coordinating welcome materials, access requests, system accounts, orientation sessions, and initial point-of-contact communications
• Assist with travel coordination, including arranging flights and lodging, preparing detailed itineraries, helping with travel authorizations, and ensuring compliance with travel policies
• Support annual performance evaluations by gathering inputs, maintaining tracking spreadsheets, scheduling feedback meetings, and preparing documentation packages
• Help compile merit increase recommendations by organizing data, assembling justification materials, and ensuring all required forms are completed and submitted on time
• Assist with requests by preparing documentation, tracking approval workflows, and following up to ensure timely processing

Skills

Attention to detail

Verbal and written communication

Critical thinking

MS Office

Organizational skills

Time management

Problem-solving

Teamwork

Education

High School Diploma

Associate’s degree in business management and/or office administration

Tools

Excel

Word

Outlook

SharePoint

Project

Visio

Job description

In support of a challenging, critical, and rewarding program that provides integrated voice, video, and data services throughout the Information Technology lifecycle, Amentum is seeking a Senior Office Administrator to join our dynamic team of IT professionals dedicated to fostering a positive and collaborative work environment. You must be a critical thinker, have a strong work ethic, and be able to work independently or as a member of a team in a dynamic environment. We value candidates who are detail-oriented while also being able to think and react quickly to emerging and unique problem sets. To be successful, you must be able to rapidly adapt and learn how to operate the front and back end of new products and processes.

Work Schedule

• 5 Days (Mon – Fri); 8 hrs/Day; 40 hrs/wkly (1000 EST – 1800 EST)

Essential Responsibilities

• Greet and check in all visitors to create a professional and friendly first impression, ensuring they understand entry procedures and program protocols.
• Arrange escorts for visitors by coordinating with available staff, confirming clearance requirements, and tracking escort responsibilities throughout the visit.
• Answer, screen, and transfer incoming phone calls promptly, providing accurate information and directing callers to the correct personnel or department.
• Monitor office supply levels by regularly checking inventory, forecasting needs, and placing timely replenishment orders to prevent shortages.
• Coordinate with facility staff for reception area needs, addressing issues like badge access, seating, and general front-office maintenance.
• Maintain and update the shared office calendar to ensure complete visibility of program activities, including meetings, deadlines, travel schedules, and team availability. Schedule meetings by reserving rooms, managing attendee lists, and preparing or distributing necessary materials and reminders.
• Provide calendar updates to team members and leadership so plans remain aligned and conflicts are identified early. Maintain accurate personnel rosters and ensure updates are made promptly when staffing changes occur.
• Create and manage mailing lists, emergency phone trees, and distribution lists used for communication across the program.
• Update organizational charts to reflect new hires, role changes, or reporting structure adjustments, ensuring leadership visibility into team composition.
• Maintain escort rosters and other administrative lists required for compliance, access control, and operational readiness.
• Organize and store all administrative documents according to program standards, ensuring they remain easily accessible and current.
• Support onboarding by coordinating welcome materials, access requests, system accounts, orientation sessions, and initial point-of-contact communications.
• Assist with travel coordination, including arranging flights and lodging, preparing detailed itineraries, helping with travel authorizations, and ensuring compliance with travel policies.
• Support annual performance evaluations by gathering inputs, maintaining tracking spreadsheets, scheduling feedback meetings, and preparing documentation packages.
• Help compile merit increase recommendations by organizing data, assembling justification materials, and ensuring all required forms are completed and submitted on time.
• Assist with requests by preparing documentation, tracking approval workflows, and following up to ensure timely processing.

Minimum Requirements

• Must have active Top-Secret clearance with SCI or the ability to acquire Top Secret/SCI
• At least 4 years of office administration/management experience
• Must be able to work a 40-hour work week, normally Monday through Friday
• Ability to work overtime during critical peaks and be available to meet last-minute requests for overtime if needed
• Ability to travel (5-10%) primarily within 75 miles
• Familiarity with MS Office applications such as Excel, Word, Outlook, SharePoint, Project and Visio
• Exceptional attention to detail; excellent verbal and written communication skills; strong critical thinking, organizational, time-management, and problem-solving skills
• Ability to work both independently and as part of a team in a dynamic environment

Security Clearance Required

Must have active Top-Secret clearance with SCI or TS with the ability to acquire SCI

Minimum Education

High School Diploma

Minimum Years of Experience

4 years of relevant experience

Preferred Qualifications

Associate’s degree in business management and/or office administration

Other Responsibilities

Safety

Amentum enforces a safety culture whereby all employees have the responsibility for continuously developing and maintaining a safe work environment. As appropriate, each employee is responsible for completing all training requirements and fulfilling all self-aid/buddy aid responsibilities, participating in emergency response tasks and serving on safety committees and teams.

Quality

Quality is the foundation for the management of our business and the keystone to our goal of customer satisfaction. It is our policy to consistently provide services that meet customer expectations. Accordingly, each employee must conform to the Amentum Quality Policy and carry out job activities in compliance with applicable Amentum Quality System documents and customer contracts. Each employee must read and understand his/her Quality Management and Customer Satisfaction responsibilities.

Procedure Compliance

Each employee must read, understand and implement the general and specific operational, safety, quality and environmental requirements of all plans, procedures and policies pertaining to his/her job. Qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, sexual orientation, gender identity, disability or protected veteran status.

#javelin #jointhepack

Compensation Details

$85,000 - $115,000

The compensation range or hourly rate listed for this position is provided as a good-faith estimate of what the company intends to offer for this role at the time this posting was issued. Actual compensation may vary based on factors such as job responsibilities, education, experience, skills, internal equity, market data, applicable collective bargaining agreements, and relevant laws.

Benefits Overview

• Health, dental, and vision insurance
• Paid time off and holidays
• Retirement benefits (including 401(k) matching)
• Educational reimbursement
• Parental leave
• Employee stock purchase plan
• Tax-saving options
• Disability and life insurance
• Pet insurance

Note: Benefits may vary based on employment type, location, and applicable agreements. Positions governed by a Collective Bargaining Agreement (CBA), the McNamara-O'Hara Service Contract Act (SCA), or other employment contracts may include different provisions/benefits.

Original Posting

10/02/2026 - Until Filled

Amentum anticipates this job requisition will remain open for at least three days, with a closing date no earlier than three days after the original posting. This timeline may change based on business needs.

Amentum is proud to be an Equal Opportunity Employer. Our hiring practices provide equal opportunity for employment without regard to race, sex, sexual orientation, pregnancy (including pregnancy, childbirth, breastfeeding, or medical conditions related to pregnancy, childbirth, or breastfeeding), age, ancestry, United States military or veteran status, color, religion, creed, marital or domestic partner status, medical condition, genetic information, national origin, citizenship status, low-income status, or mental or physical disability so long as the essential functions of the job can be performed with or without reasonable accommodation, or any other protected category under federal, state, or local law. Learn more about your rights under Federal laws and supplemental language at Labor Laws Posters.