TN&A plans and performs remediation investigations, assessments, and studies for government and private sector customers. We have conducted a full range of investigations that include work plans, multi-media sampling, integrated field analytical support, hydrogeologic studies, modeling, and geotechnical investigations, as well as risk assessment, treatability studies, and report preparation. To deliver value, TN&A applies innovative investigation techniques to maximize the data returned on investment. To enhance our investigation capability, TN&A operates our own Geoprobe® direct push technology (DPT) rig that uses static weight and percussion to drive sampling probes for discrete and non-discrete sampling of soil and groundwater.

TN&A tailors remedial planning to fit the needs of each customer. Where remedial design is expected, we typically collect anticipated geotechnical data during remedial investigation to avoid the need for repeated investigation. Where appropriate, we integrate environmental assessments with site investigations to address ecological and human health risks. We design focused and cost-effective investigations aimed to generate data required for decisions.

In Maywood, CA, TN&A is performing a CER­CLA RI/FS at the Pemaco Superfund Site, a former chemi­cal blending facility. Chemicals of concern included chlorinated and aromatic solvents, flammable liquids, oils and specialty chemicals—over 55 chemicals of concern have been identified. The facility is next to the Los Angeles River and is planned to be developed as a city park. The RI scope included dynamic work plans with flexible field decision rules and onsite analytical support, surface and subsurface soil sampling using drill rigs and direct push technology (DPT), soil vapor sampling, and installation and sampling of groundwater monitoring wells. In the field, TN&A used an innovative membrane interface probe with a direct sampling ion trap mass spectrometer to obtain real-time, definitive chemical data that allowed determination of stratigraphic profiles of concentrations of individual VOCs versus depth, and enabled rapid in-field identification and delineation of NAPL zones.