With the market for Environmental Site Assessments growing in response to the requirements of lending institutions, the need to collect subsurface samples quickly and inexpensively is greater today than ever before. ASTM, through committee E-50, has developed standardized procedures for the performance of a Pre-Transaction Environmental Screening and for a Phase I Environmental Site Assessment. Standards for the performance of subsurface sample collection during a Phase II Environmental Site Assessment are currently being drafted by committee E-50.
This paper discusses numerous sample collection techniques that have been successfully employed during Phase II Assessments and presents case histories of their application.
The collection of shallow soil samples is described using commercially available hand augers and hand-driven core samplers. These devices are modified with extensions to collect deeper samples from storm drains and leaching pools.
The performance of soil gas surveys are described using both hand-driven sample probes and vehicle-mounted, hydraulically driven vapor probes. Once the soil vapor is collected at the ground surface, a sample of the media is either analyzed on-site using a field-operated detection device or delivered to a laboratory for analysis.
Application and case histories of the Geoprobe(™) sampling system, a form of “direct push” technology, are described. This device uses vehicle-mounted, hydraulically-driven sample probes. The probe can be advanced to depths as great as 100 feet below grade and can retrieve soil, soil gas and groundwater samples.
Use of standard truck-mounted drill rigs are also considered. Collection of soil samples are discussed using standard techniques such as a split-barrel core sampler (ASTM Method D 1586-84, Standard Method for Penetration Test and Split-Barrel Sampling of Soils) and installation of monitoring wells: Applications and case histories of the Hydropunch(™) in-situ groundwater sampler are also described. This device allows for the collection of a groundwater sample during the process of performing a soil boring without the installation of a monitoring well.
The method selected for a given project will vary depending on site-specific criteria such as the depth to groundwater and the subsurface geology. This paper discusses the advantages and disadvantages of each method. It also evaluates the criteria that should be considered in selecting in-situ sampling devices, such as a driven sampling probe, versus a permanent monitoring well.