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You are here: Home » Resources » Articles » What Are Sampling Methods for Phase II Environmental Testing?

February 13, 2019

What Are Sampling Methods for Phase II Environmental Testing?

By Kristine MacWilliams, PE


When a Phase I Environmental Site Assessment (ESA) identifies a recognized environmental condition (REC) or the potential for impacts to the subsurface at a site, most clients request to evaluate the potential impacts by performing Phase II Environmental Testing. The purpose of a Phase II Environmental Report is to evaluate the presence, or absence of, petroleum products or hazardous substances in the subsurface of the site. A trained, licensed, experienced staff of geologists and engineers that possesses expertise in Phase II Environmental project design performs these assessments per the ASTM E1903-11 Standard Guide.

Drilling Methods for Phase II Environmental Testing

Drilling methods used most often by scientists and geologists during Phase II Environmental Testing projects include:
• Push Probe
• Hollow Stem Auger
• Hand Auger
• Mud Rotary
• CPT Drilling
Other subsurface drilling technologies include sonic drilling, telescope drilling, air rotary, and solid stem auger.
Sampling Media and Methods for Phase II Environmental Testing
The media sampled, sampling methods and laboratory analysis components of a Phase II ESA vary by site, client need, risk tolerance and nature of the REC identified in a Phase I ESA. However, they may include one or more of the following:

Collection of Surface Soil and Water Samples
When a REC or area of concern (such as surface staining or sheen on surface water) is identified at the surface on the property, field testing is conducted to collect samples directly from surface soil and water surfaces to evaluate the degree and extent of the identified impacts through laboratory analysis of the collected samples.

Soil Gas Sampling
When the Phase II Environmental Site Assessment is being done to investigate volatile organic compounds (VOCs), the geologist designing the Phase II scope should consider sampling for soil gas instead of, or in addition to, soil samples. Soil gas sampling is particularly advantageous in porous media such as sands.  Soil gas samples can be collected as sub-slab (just beneath the slab) or from various depths within the soil column.

Collection of Subsurface Soil Borings
If a REC is identified beneath the surface at the site (for example and underground storage tank or hydraulic lift), samples must be collected below the surface (subsurface) by drilling to gain access. Samples are analyzed both on site through field screening and mobile laboratories as well as through testing at a fixed laboratory.

Subsurface Groundwater Monitoring
If the subsurface RECs or impacts is suspected for groundwater (via an underground storage tank or from impacts migrating from soils or even off-site impacted groundwater), monitoring wells are installed to the depth of groundwater, which varies depending on where the site is located in order to collect groundwater samples for laboratory analysis.

Drum Sampling
Unmarked or old drums can be the source of a REC. Collection, and laboratory analysis of drum contents can determine the type of hazardous material and proper disposal process.

Dry Wells, Floor Drains and Catch Basins
Materials from subsurface structures can often contain liquid or solid substances that are considered a REC based on the potential for substances to leak into the surrounding subsurface. Sampling and analysis of the substances in these structures can determine nature of the substances and if additional investigation is warranted.

Transformer and Capacitor Sampling
Old abandoned transformers are commonly a source of polychlorinated biphenyls (PCBs), a hazardous chemical contaminant. Proper sampling and analysis of transformer oil can confirm the presence or absence of PCBs.

Buried Tanks, Drums and Waste
Sites with old buried tanks or drums may contain waste or other hazardous materials. A geophysical survey uses equipment passed over the ground in grids to evaluate possible presence of buried tanks. If the geophysical survey identifies any suspect features, test pits may be set up to expose tanks or drums, while also collecting subsurface soil samples for analysis.

Underground Storage Tanks (USTs)
Until the 1980s, most storage tanks were made of bare steel, which can corrode over time and cause a leaking underground storage tank (LUST) which would leak into the soil and groundwater. There are strict Federal and State guidelines regulating USTs containing petroleum and hazardous chemicals. Fully operational storage tanks are tested to make sure they comply with these regulations, in addition to a thorough review of records, permits and history of documented leaks. Tank pits or former, excavated tanks and tank systems are typically identified as RECs. Many options and cost-effective solutions exist for underground storage tank removal from a site.

Indoor Air Quality (IAQ) Sampling
The spread of hazardous substances through from the subsurface into buildings can often affect air quality inside of a structure. Collection and analysis of air samples is compared to outdoor ambient conditions and indoor health quality standards.

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