Soil Contamination

Aztech geologists are talented, thorough and well versed in conducting soil investigations that range from advancing soil borings in shallow and/or deep overburden to bedrock coring. The  scope of the subsurface soil investigation is developed based on the findings of the Phase I Environmental Site Assessment or from other existing information relative to the site to be investigated. The goal is to determine if any environmental impacts to the subsurface soils exist at the site.

Aztech geologists and drillers collaborate to advance soil borings to depths sufficient to spatially and vertically evaluate the soil quality down to the top of bedrock, if necessary. Depending on the nature of the soil materials present beneath a site, soil borings are typically advanced using a track or truck‐mounted hydraulic drill rig by means of direct‐push probing methods with macrocore sampling or split spoon sampling. Depth‐discrete soil samples are collected and the soil samples are examined in the field for grain size, color, odor (if present) and moisture content. Each soil sample is placed in an airtight container and the headspace is screened in the field using a photoionization detector (PID) calibrated to a standard isobutylene calibrant gas.

In many cases, the soil sample from each soil boring location exhibiting the highest PID reading in the headspace is submitted to an approved laboratory for analysis of the contaminant of concern (COC). Typically, in the absence of PID readings or other evidence of COCs in the soil headspace, the soil sample collected from the soil/water interface is submitted for laboratory analysis. Drill logs containing pertinent information, such as the geotechnical qualities and classification of soils, the location of the soil water interface and, the depth interval of the soil sample analyzed by the laboratory, are kept for each respective borehole.  The soil characteristics and analytical data obtained from each borehole tell a story. Aztech geologists evaluate these data and are able to determine the presence and concentration of COCs, the depth and lateral distribution of COCs and, the pathway in which the COC has traveled through the various soil types. This information allows us to identify, define and delineate the area in the subsurface in need of remedial activities and develop a remedial approach specific to the COC and, the job site.