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Environmental Services

TGI provides a range of environmental site assessment and remediation services to support our clients manage environmental issues related to toxic substances in soil and groundwater. Environmental site assessment and remediation services are among TGI’s core practice areas and include:  

  • Phase I and Phase II ESAs

  • Remedial Investigations for Soil & Groundwater Contamination

  • Risk Assessment/Preliminary Endangerment Assessment

  • Feasibility Studies

  • Pilot & Bench-Scale Tests

  • Remedial Design

  • Regulatory Assistance

  • Implementation and Monitoring of Corrective Action

  • ​Environmental Litigation Support

Site Assessment & Characterization


TGI provides comprehensive environmental site assessment (ESA) services, ranging from industry-standard “Phase I” ESAs to much more extensive investigations to characterize and quantify soil and groundwater contamination at impacted sites.  TGI personnel have completed site assessments and site characterization studies related to subsurface soil and groundwater contamination at a wide variety of sites, including investigations at numerous state and federal Superfund sites.

Our site assessment experience includes the performance of Phase I ESAs and Preliminary Endangerment Assessment (PEAs) at proposed school sites in accordance with California Department of Education and Department of Toxic Substances Control requirements.
We are highly experienced at planning and executing remedial investigations under various local, state, and federal programs and protocols.  We have used intrusive and non-intrusive techniques to cost-effectively determine the type, severity, and extent of contamination, and the controlling subsurface geologic and hydrogeologic migration pathways.  Our staff has extensive experience in the application of virtually all types of environmental investigation techniques and geophysical testing for wide-ranging site and subsurface conditions.  


Corrective Action & Remediation


TGI personnel have developed, permitted and implemented remedial action plans for sites where soil and/or groundwater have been impacted by many different types of contaminants including petroleum hydrocarbons, halogenated solvents, PCBs, pesticides, and toxic metals.  We have successfully completed remedial actions to both statutory and risk-based cleanup levels.  We have evaluated and utilized a variety of approaches for contaminant recovery, offsite disposal and onsite/in situ treatment.  Examples of techniques that we have employed include vapor extraction, air sparging, pump-and-treat systems, thermal and catalytic oxidation, incineration, encapsulation, carbon adsorption, and enhanced biodegradation. 

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