Team

Driven by leaders with a cohesive vision and strong entrepreneurial spirit, the company has evolved into a diverse environmental, engineering, and construction services firm. Since 1997, ERRG has rapidly grown to a team of nearly 300 employees based in strategic locations throughout the continental United States, Hawaii, and Guam.

Directors

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Cynthia Liu, PE
President and CEO

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  • Ms. Liu is ERRG’s President and CEO responsible for company-wide business management, engineering oversight, as well as selected program and project management. She works with clients and agencies to develop effective solutions for site remediation and closure.  Her background includes investigation, remedy selection, and implementation of remedial systems for addressing contaminants in complex environments.  She works closely with clients and stakeholders to proactively drive environmental cleanup and restoration projects to successful completion.   Ms. Liu is heavily involved with developing business for munitions response under CERCLA and environmental compliance and restoration throughout the Pacific Rim.

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Rowan Tucker
Chief Remediation Officer

  • Mr. Hall is ERRG’s Chief Technical Officer responsible for oversight and technical quality review of all projects, including project planning, field execution, and all deliverables. He has construction, site assessment, remedial action, and information technology experience. Mr. Hall also serves as ERRG’s Program Manager for several large Indefinite Quantity/Indefinite Delivery contracts for clients including the U.S. Navy and U.S. Army Corps of Engineers.

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  • Mr. Tucker is ERRG’s Chief Remediation Officer responsible for remediation project oversight, health and safety, emergency response, and waste disposal coordination. Mr. Tucker has extensive experience in the environmental and hazardous waste management industry.

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Randy Randall
Chief Operations Officer

  • Mr. Tang is experienced in the field of civil and geotechnical engineering and construction management. His specialties include civil design, grading and excavation planning, drainage design and calculations, geotechnical field investigations and laboratory testing programs, seismic response analysis, static and seismic slope stability analyses, settlement analysis, liquefaction analysis, landfill cap infiltration computer modeling, and material evaluations. Mr. Tang also has extensive experience in field construction quality assurance/quality control of landfill lining systems, deep and shallow building foundations, and complex ground improvement projects using vibrofloatation, deep dynamic compaction, and chemical grouting.

David Tang, PE, GE
Principal Engineer

Bradley Hall, PG, PMP
Chief Technology Officer

  • Mr. Randall, Chief Operations Officer, has a broad base of experience in the environmental field. His background includes extensive health and safety, site assessment, emergency response, and federal Superfund removal action project management experience. For several years Mr. Randall was a dedicated contractor to the U.S. Environmental Protection Agency in Region 9.

Corporate Leadership

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Kim Jackson
 Chief Financial Officer

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  • Ms. Jackson manages ERRG’s finance and contract functions and has extensive experience providing finance, contract, accounting, and tax services.  Her responsibilities include implementing processes, procedures, and reviews that significantly improve operations, including adhering to federal and state regulations, while reducing ERRG’s exposure to risk.  Ms. Jackson also has expertise in the administration of all contract types (firm-fixed price, time and materials, and cost-plus). 

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Heather Wollenburg, CIH, CSP, PMP
Corporate H&S Manager

  • As ERRG's Chief Growth Officer, Ms. Grasso is responsible for identifying, tracking, evaluating, and closing new business opportunities. She works closely with internal and external stakeholders to formulate and implement marketing and business development strategies and identify key clients and pursuits, including oversight of client and teaming partner relationships.  

Melissa Grasso
Chief Growth Officer

  • Ms. Wollenburg has been with ERRG since 2007 and was more formally incorporated into ERRG’s Safety Department in 2017 as the Corporate H&S manager for DoD projects.  She works with the directors to develop and implement compliant programs for the company.  She manages all aspects of corporate and project health and safety.  She works with designated Regional Safety Coordinators and Site Safety Officers located throughout the company to implement and administer the company’s safety program at a regional and project level.  Ms. Wollenburg reviews site-specific safety documents, oversees the safety training program, and works to ensure compliance with requirements at local, state, and federal levels. 

Regional Managers

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Dan Lohr, PG
Bay Area

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  • Mr. Lohr is a Senior Project Manager and Professional Geologist with experience working under Federal, state, and local laws and regulations and guidance under RCRA/CERCLA programs. Mr. Lohr’s experience covers a wide range of environmental services including remediation, investigation, assessment, construction, and compliance. Mr. Lohr has experience working with multiple stakeholders including regulatory agencies, local municipalities, community groups, and businesses. Mr. Lohr is dedicated to safety, with no lost time incidents on projects managed/overseen throughout his career. 

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Tom Mills, PG
MEC

  • Dr. Pringle is ERRG's Regional Manager responsible for business operations throughout Southern California and Texas. He has more than 25 years of experience managing environmental remediation, construction, hazardous waste, and infrastructure projects for both federal and private-sector clients. His background includes leadership of complex environmental restoration programs, remedial action projects, environmental construction services, and multidisciplinary project teams operating in highly regulated environments.

    As Regional Manager, Dr. Pringle is responsible for strategic growth, client development, operational performance, and the successful execution of projects across his regions. He works closely with clients, project teams, and company leadership to develop practical solutions that achieve technical objectives while maintaining a strong focus on safety, quality, schedule, and cost performance. Dr. Pringle is committed to building and mentoring high-performing technical and management teams that consistently deliver value to clients and exceed project expectations. He believes that long-term success is driven by collaboration, accountability, and a culture of continuous improvement. Through this approach, he has helped expand client relationships, support business growth initiatives, and position ERRG as a trusted partner for environmental and construction-related services.

    He is particularly focused on identifying new market opportunities and developing innovative service offerings that align with client needs while supporting ERRG's long-term strategic objectives.

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  • Mr. Mills is a geoscientist with experience in the areas of CERCLA and RCRA investigations. As ERRG’s Munitions Response Division Manager, he has extensive experience conducting Military Munitions Response Program (MMRP) investigations using geophysical investigations. Mr. Mills is a subject matter expert in munitions constituent sampling and has developed and authored multiple standard operating procedures for environmental field procedures.  Mr. Mills is highly proficient in the areas of technical approach development and planning, field operations management, environmental and geologic sample and data collection, analysis and data evaluation, and technical writing.  Mr. Mills manages large MMRP projects for the USACE, U.S. Navy and commercial clients. 

Steven Applegate
Guam

Scott Pringle, PhD
Southern California

  • As ERRG’s Guam Regional Manager, Mr. Applegate is focused on MMRP investigation and Environmental Remediation projects for NAVFAC, AFCEC, USACE, and commercial clients in the Marianas and Indo-Pacific region. A Retired U.S. Army EOD Technician, he has extensive experience managing CONUS and OCONUS military and civil projects. Mr. Applegate is a SME in the development of MMRP standard operating procedures, MEC process improvement beginning in project design, and the seamless integration of construction and MMRP projects.

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Jason Gulbransen
Sacramento

  • Mr. Gulbransen provides regional leadership for the planning, coordination, and execution of hazardous waste remediation and clean construction projects. He brings more than 30 years of experience with full-service environmental remediation firms, supporting complex projects from pursuit through implementation and completion. His experience includes program strategy and bidding, permit acquisition, regulatory agency coordination, and oversight of multidisciplinary project teams and subcontractors. In his regional management role, he provides guidance on project capture, contract execution, pre-mobilization planning, schedule performance, and health and safety compliance across multiple projects. He also supports project operations, sequencing, vendor and subcontractor management, and serves as a key liaison with regulatory agencies and client representatives.