Senior EHS Engineer

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We design, build, and test next generation weapon systems to give America and its Allies a definitive edge in defense capabilities. The Senior Environmental, Health & Safety (EHS) Engineer supports manufacturing, R&D, and test operations in a fast-paced startup environment by serving as the technical authority for hazard identification, risk assessment, and control strategy. This role partners closely with engineering and operations teams to integrate EHS requirements into product design, process development, and day to day operations so that work can be performed safely and efficiently. The Senior EHS Engineer leads safety in design activities, including risk assessments, Job Hazard Analyses (JHAs), and safety reviews for manufacturing, testing, and new or evolving processes. The role defines what hazards exist, how significant they are, and what controls are required, while also overseeing the technical framework for EHS programs, industrial hygiene strategy, and emergency preparedness to ensure regulatory compliance and operational readiness. Success in this role requires strong technical judgment, comfort operating in ambiguity, and a hands-on approach to building scalable EHS systems while effectively influencing cross functional teams as the organization grows. Responsibilities Integrate EHS requirements into product and process design by leading safety in design activities including risk assessments, Job Hazard Analyses (JHAs), and formal hazard analyses (HAZOP, LOPA, FMEA) from concept through production and sustainment. Define hazard classifications, risk rankings, and the engineering and administrative control strategies required to ensure hazards are effectively controlled across manufacturing, testing, and R&D operations. Establish industrial hygiene and exposure control frameworks to protect employee health and meet applicable regulatory requirements. Interpret OSHA, Cal OSHA, EPA, fire code, and DoD requirements and translate them into site specific EHS programs and procedures. Own the technical framework for core EHS programs that govern how hazardous work is performed across manufacturing, testing, and R&D operations. Lead investigation and analysis of significant incidents and near misses to identify systemic causes and drive risk-reduction actions. Serve as the technical authority for regulatory inspections, audits, and agency interactions. Design and maintain site Emergency Action Plan and emergency response strategies. Basic Qualifications Bachelors degree in Environmental Engineering, Chemical Engineering, Industrial Engineering, Safety Engineering, or a related technical field. 3+ years of experience supporting EHS programs in manufacturing, R&D, or test environments. Experience conducting hazard analyses and risk assessments. Experience supporting industrial hygiene activities, including exposure evaluations, sampling, or coordination with IH professionals. Working knowledge of applicable EHS regulations and standards (e.g., OSHA/Cal-OSHA, EPA, DOT, fire code). Hands-on experience supporting core occupational safety programs (e.g. machine guarding, PPE, lockout/tagout, electrical safety, hazard communication). Ability to operate independently in a fast-paced, ambiguous startup environment and partner effectively with engineering and operations teams. Ability to travel as needed to support operations, testing, or program needs. Ability to meet U.S. export control requirements (e.g., U.S. Person under ITAR/EAR, as applicable). Preferred Skills and Experience 5+ years of experience supporting EHS programs in manufacturing, R&D, or high-hazard environments. Experience in defense, aerospace, advanced manufacturing, energetics, propulsion, or similarly regulated industries. Experience integrating EHS requirements into product or process design and participating in engineering or safety design reviews. Familiarity with EHS management systems or structured program frameworks (e.g., ISO 14001, ISO 45001). Professional certification such as CSP, CIH, ASP, or progress toward certification. Experience working in a startup or rapidly scaling organization. All employees are granted long-term stock incentives as part of their employment at Castelion. All employees receive access to comprehensive medical, vision, and dental insurance, and the company offers four weeks of paid time off per year. Leadership Qualities Bias to Action and Creative Problem Solving . Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Ability to personally resolve minor issues in development without requiring significant support. High Commitment, High Initiative . A successful candidate will have a genuine passion for Castelion's mission and consistently look for ways to contribute to the company's technical goals and prevent hardware blockers. Ability to work in a fast paced, autonomously driven, and demanding atmosphere. Strong sense of accountability and integrity. Clear Communicator . Proactively communicates blockers. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity. To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State. Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status. #J-18808-Ljbffr Castelion