Senior OT Security Engineer

Job

Exempt

Oldcastle Infrastructure™, a CRH company, is the leading provider of utility infrastructure solutions for the water, energy, and communications markets throughout North America. We’re more than just a manufacturer of precast concrete, polymer concrete, or plastic products. We’re a trusted and strategic partner to engineers, contractors, distributors, specifiers, and more. With our network of more than 80 manufacturing facilities and more than 4,000 employees, we’re leading the industry with innovation and a safety-first mindset.

Oldcastle Infrastructure - Built For Life from Oldcastle Infrastructure on Vimeo.

The Senior OT Security Engineer is responsible for securing manufacturing Operational Technology (OT) environments while preserving safety, reliability, and production uptime. This role supports traditional manufacturing operations by applying practical, risk-based cybersecurity controls to industrial control systems and plant networks. The position sits within the IT / Cybersecurity organization and works closely with plant engineering and operations teams to secure legacy and modern OT systems without disrupting production.

• This role will work hybrid out of our office in the Sandy Springs, GA area.

OT Security in Manufacturing Environments

• Protect plant‑floor control systems (PLC, SCADA, HMI) from cybersecurity threats while maintaining stable operations.
• Implement OT network segmentation, firewalls, and DMZs appropriate for legacy manufacturing environments.
• Define and support secure remote access for vendors and internal plant support teams.
• Ensure OT security controls are practical, documented, and support production uptime.

Risk, Compliance & Change Control

• Perform OT cybersecurity risk assessments focused on real manufacturing risks (downtime, safety, quality).
• Support regulatory, insurance, and internal audit requirements related to OT cybersecurity.
• Ensure OT systems follow IT change management processes adapted for plant operations.
• Document and track security risks, exceptions, and compensating controls.

Vulnerability & Incident Management

• Identify OT vulnerabilities and develop remediation plans that consider operational constraints.
• Coordinate patching, configuration changes, and mitigations during planned maintenance windows.
• Support OT‑related cybersecurity incidents and investigations in coordination with IT security teams.
• Work with plants to implement lessons learned from incidents and near‑misses.

Standards & Operational Discipline

• Develop simple, repeatable OT security standards suitable for traditional manufacturing sites.
• Maintain OT asset inventories, network diagrams, and security documentation.
• Review vendor and system integrator solutions to ensure they meet minimum security requirements.
• Support lifecycle planning for aging OT systems and end‑of‑support risks.

Collaboration & Plant Engagement

• Serve as a trusted cybersecurity partner to plant managers, engineers, and maintenance teams.
• Work closely with OT integration and IT infrastructure teams.
• Provide security guidance and education to plant personnel in practical, non‑theoretical terms.
• Mentor junior engineers and promote consistent security practices across sites.

• Bachelor’s degree in Information Technology, Engineering, or equivalent experience.
• 7+ years of experience in OT, cybersecurity, or manufacturing environments.
• Hands‑on experience securing industrial control systems in traditional manufacturing plants.
• Strong knowledge of industrial control systems (PLC, SCADA, HMI).
• Experience with OT networking and industrial protocols (Ethernet/IP, Modbus, OPC).
• Hands‑on experience with firewalls, segmentation, and secure remote access in plant environments.
• Understanding of legacy systems and long OT asset life cycles.
• Working knowledge of OT security standards (IEC 62443, NIST) applied pragmatically.
• Experience in multi‑site, legacy‑heavy manufacturing environments.
• Familiarity with IT security tools (SIEM, IAM) as they relate to OT.
• Certifications such as GICSP, IEC 62443, CISSP, or CCNA Security.
• Experience working through plant outages, maintenance shutdowns, or…