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 and Hawaii.


Cynthia A. Liu, PE, President and CEO

Ms. Liu is ERRG’s President and CEO responsible for companywide business management, engineering oversight, as well as selected program and project management. She has more than 25 years of experience working with clients and agencies in developing 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.

Rowan Tucker, Remediation Services

Mr. Tucker is ERRG’s Manager of Remediation Services responsible for remediation project oversight, health and safety, emergency response, and waste disposal coordination. Mr. Tucker has more than 23 years of experience in the environmental and hazardous waste management industry.


Randy Randall, Operations

Mr. Randall 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.


Brad Hall, PG, PMP, Chief Technical Officer

Mr. Hall is ERRG’s Chief Technical Officer and Vice President responsible for oversight and technical quality review of all projects, including project planning, field execution, and all deliverables. He has more than 25 years of 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.


David Tang, PE, GE, Principal Engineer

Mr. Tang has 29 years of professional experience 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.