Soil and groundwater contamination may result from numerous sources. In most cases, the source(s) is related to historic operations such as retail fueling, industry or manufacturing, landfills, mines, and even agriculture at the site, or, in some cases, the source(s) may have been associated with prior land use on potentially one more neighboring properties. ART provides services for investigation, and, if necessary, remediation of soil and groundwater contamination. The key to developing an effective remediation program is to understand the nature and extent of contaminants in the subsurface. ART uses an array of costeffective investigation methods to fully understand the geology, hydrogeology, contaminant distribution, and contaminant fate and transport. The following summarizes select investigation methods commonly used by ART in conducting remedial investigations:

Phase One investigations are conducted to evaluate property that has not previously been investigated. These investigations are typically non-intrusive and include site visits, review of regulatory agencies file records of the site and neighboring properties, and review of aerial photographs to evaluate potential historic use of the Site and surrounding area Phase Two investigations consist of the follow-up evaluations for information collected during the Phase One.

Phase Two includes air, soil and groundwater sampling and analysis, drilling and installation of groundwater monitoring wells, and preparation of a report that summarizes and discusses the environmental impact of the sampling and analysis results, and provides recommendations for additional work.

Geologic Assessments are conducted to understand the site geology and develop a site conceptual model. This includes the following - review of aerial photographs to evaluate surface features such as potential faults; field geologic mapping to determine rock/soil types and potential geologic features such as fractures and faults; logging of soil collected from borings to evaluate subsurface lithology; and, geophysical surveys to evaluate subsurface geologic structures, depth to bedrock, geologic contacts, faulting, and even differing groundwater chemistry.

Hydrogeologic Assessments are conducted to develop a site conceptual model and obtain a comprehensive understanding of groundwater flow direction and gradient, nearby surface water features, local groundwater use such as nearby pumping wells, and recharge zones. These are performed by installing piezometers and groundwater monitoring wells, installing multiple well casings in a single borehole to evaluate vertical gradients within a complex saturated flow system, performing tracer studies to evaluate horizontal and vertical flow in aquifer systems, and to evaluate potential interaction of surface water and groundwater, and aquifer testing to estimate aquifer properties such as hydraulic conductivity, storativity, seepage velocity, and contaminant migration rate As part of remedial investigation activities, ART also uses soil gas sampling to delineate volatile contaminants in shallow groundwater, and evaluate potential risks for exposure to indoor air contaminants in structures overlying contaminants. Drilling methods commonly used by ART to determine subsurface lithology and install monitoring wells include Geoprobe continuous core, hollow-stem auger with core barrel, mud rotary, air rotary, and sonic. ART also utilizes cone penetrometer testing (CPT) to evaluate subsurface lithology, at depths exceeding 100 feet below ground surface (bgs), based on soil friction and penetration resistance.

SOIL AND GROUNDWATER REMEDIAL DESIGN