A Phase II Environmental Site Assessment (ESA) is a detailed investigation conducted to evaluate the presence or absence of hazardous materials or petroleum products in the soil, groundwater, or surface water at a site. This type of assessment is usually carried out following a Phase I ESA, which might have identified potential contamination risks based on historical data, site inspections, and surrounding land use.
What Does a Phase II ESA Analyze?
The primary objective of a Phase II ESA is to confirm the presence of contaminants and quantify their concentrations. This is accomplished through several key analyses:
Soil Sampling and Analysis: Soil samples are collected from various depths and locations around the site to test for contaminants such as heavy metals, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and other hazardous substances.
Groundwater Sampling and Analysis: Groundwater monitoring wells are installed to sample groundwater and assess if contaminants are present below the surface. This is particularly important if the site is near a water source or if the Phase I ESA suggested a risk of groundwater contamination.
Surface Water and Sediment Analysis: If the site is near a body of water, samples of surface water and sediment may be collected to determine if contamination has spread beyond the site boundaries.
Soil Gas Sampling: In some cases, the assessment may include soil gas sampling to detect volatile chemicals that might have evaporated from the soil or groundwater into the soil gas (air spaces within the soil).
Scope of Work in a Phase II ESA
The scope of work for a Phase II ESA typically includes:
Site Investigation: Conducting fieldwork to collect soil, groundwater, surface water, sediment, and soil gas samples. The location and depth of samples are determined based on potential sources of contamination identified in the Phase I ESA.
Laboratory Analysis: Samples are sent to certified laboratories for analysis. The labs use various techniques to identify and quantify the presence of contaminants.
Data Evaluation: The results from the lab are analyzed to determine the extent of contamination. This involves comparing detected concentrations against regulatory limits and guidelines to assess potential risks to human health and the environment.
Reporting: The findings are compiled into a comprehensive report that details the methods, findings, and conclusions of the investigation. This report may also include recommendations for further action, such as remediation or additional assessment if contamination is confirmed.
Case Study: A Manufacturing Plant
Let's consider a hypothetical case study of a manufacturing plant that undergoes a Phase II ESA. This plant has been operational for over 50 years, producing various metal parts and components. During a Phase I ESA, historical records revealed that the plant had used and stored hazardous chemicals, including solvents and heavy metals, on-site. This raised concerns about potential soil and groundwater contamination.
Phase II ESA at the Manufacturing Plant:
Site Investigation:
Soil Sampling: Samples were taken from areas around the chemical storage units, the production area, and the waste disposal zone. Multiple depths were tested to understand how deep the contamination might have penetrated.
Groundwater Sampling: Monitoring wells were drilled around the site to collect groundwater samples. The wells were strategically placed based on the site's topography and the likely direction of groundwater flow.
Soil Gas Sampling: Given the use of volatile solvents, soil gas samples were also collected to check for vapor intrusion risks that could affect indoor air quality.
Laboratory Analysis:
The samples were analyzed for a range of potential contaminants. In this case, high concentrations of VOCs and heavy metals such as lead and chromium were detected in both soil and groundwater samples.
Data Evaluation:
The concentrations of contaminants were compared to state and federal regulatory limits. It was found that the levels of lead and VOCs exceeded safe limits in several areas of the site, indicating significant contamination.
Reporting and Recommendations:
The final report concluded that there was widespread contamination of both soil and groundwater at the manufacturing plant. It recommended a comprehensive remediation plan, including soil excavation and treatment, groundwater pumping and treatment, and soil vapor extraction to remove contaminants from soil gas.
This case study illustrates the critical role of a Phase II ESA in identifying environmental risks and guiding necessary remediation efforts. By thoroughly analyzing the presence and extent of contamination, a Phase II ESA helps protect public health and the environment while providing a clear path forward for site management and cleanup.
September 3, 2024, collective of authors of MMCG Invest, LLC
Sources: USDA, MMCG database
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