Groundwater monitoring is a crucial aspect of environmental management, helping to detect and manage potential groundwater contamination. However, the frequency and duration of monitoring can vary depending on site conditions and regulatory requirements. This page from Remediation Risk Management provides valuable insights into determining the necessary amount of groundwater monitoring, factors that affect monitoring requirements, and how to determine the appropriate frequency and duration of monitoring.
Everything has a beginning, middle, and end - even groundwater monitoring.
The Beginning. After contamination is identified in groundwater at a property, it’s common practice for the local environmental oversight agency to require groundwater monitoring. In California, the response to groundwater contamination is prescribed in State Water Resources Control Board Resolution 92-49 (SWRCB 92-49). This usually comes in the form of a regulatory directive - a letter arrives in the mailbox.
The Middle. The directive usually requires investigation, cleanup, and reduction of contamination by completing the following phases under their oversight:
1. Initial site assessment
2. Soil and groundwater investigation
3. Cleanup and reduction
4. Verification monitoring
The thing is, groundwater monitoring usually begins with initial site assessment and ends with long-term verification monitoring - which may take up to 10 years to complete.
What is groundwater monitoring? In essence, it’s measuring how deep groundwater is below the ground and collecting samples of groundwater for various tests. Groundwater is reached through wells that can be temporary or permanent. The wells are built in holes drilled through the soil into the groundwater. Sometimes, no well is used and groundwater is monitored using a bare hole.
During the initial site assessment phase, groundwater monitoring is used to identify the type and general location of contamination. During investigation and cleanup, groundwater monitoring is used to observe changes in contaminated groundwater and the effects of cleanup and contamination reduction. Long-term verification monitoring is used to build confidence that contamination left in place will not cause future problems. It's easy to see how groundwater monitoring seems to go on and on.
Groundwater monitoring is done to answer the following questions:
- What contaminated the groundwater?
- Where is the contaminated groundwater?
- How contaminated is the groundwater?
- What direction does the groundwater flow?
- How does the contaminated groundwater change over time?
The answers to these questions provide much of the information used to complete investigation, cleanup and reduction of contamination - and receive environmental case closure.
As more information about the groundwater contamination becomes available, groundwater monitoring becomes more focused. As a result, it might be possible to reduce monitoring costs by reducing the monitoring frequency, the number of wells monitoring, or the number of tests performed.
The End. Groundwater monitoring ends when contamination levels no longer need watching. All the questions about groundwater contamination have been answered.
Early on - the what, where and how of contaminated groundwater are answered in the preliminary and investigation phases. Contaminant cleanup and reduction continue, and after a few years the seasonal patterns of groundwater flow and contaminant levels are generally understood. Over this period, the decrease in groundwater contamination over time is well established. There comes a point where the groundwater monitoring information shows that even with groundwater contamination safely left in place, cleanup goals will be reached in a reasonable time.
Finally verification monitoring is done to record final site conditions for environmental case closure. Groundwater monitoring usually stops at this point because in most cases verification monitoring supports case closure.
Groundwater monitoring begins with a regulatory directive and ends with a regulatory directive; No Further Action - Case Closure.
We answered the question about how much groundwater monitoring it takes. We described the beginning, middle and end of groundwater monitoring, and how it follows the phases of contamination investigation, cleanup, reduction and case closure. If you’re somewhere around the beginning, middle, or end of your own groundwater monitoring experience, and need some help or a second opinion, give us a call or click the button below for a free consultation. We have over 30 years of experience in completing environmental investigation, cleanup and reduction - including groundwater monitoring.