Companies have been founded around the idea of providing consumers with dependable data. For example, when you want to buy a used car, you can purchase a report that is nothing more than historical data on the car . . . repairs, accidents, etc.
Reports such as this are useful only if the data are accurate.
In the environmental business, all projects depend on accurate data; in fact, all projects live and die based on the data!
Accurate Environmental Data Needed for Sound Decisions
If your data are not accurate and representative of actual site conditions, how can you ever hope for your remediation to succeed? If your data are not accurate, how do you know if the property you are purchasing is not contaminated or your remediation project is complete?
Reliable environmental data begins with sample collection, and, unfortunately, this is often given little thought. The following is one specific observation relating to sample collection:
Soil and groundwater samples often collected improperly
United States Environmental Protection Agency Method 5035 Issues: The United States Environmental Protection Agency (USEPA) Method 5035 was introduced to facilitate the collection of more representative volatile organic compounds (VOC) samples. USEPA Method 5035 transfers the responsibility of preserving the soil sample to the field technician from the laboratory technician. This change was designed to limit VOC losses during sampling, transport, and subsequent “sub-sampling” of the soil in the laboratory.
USEPA introduced Method 5035 in 1996, and Method 5035 has been employed in some states since at least 1998 . . . Yes, 13 years prior to Ontario adopting this method. We are just “catching up.”
After using Method 5035 for more than 15 years in the U.S., it is generally believed that this method provides far more accurate data, which, if evaluated properly, should allow for better technical and business decisions.
Now that we are using Method 5035 soil sampling protocols in Ontario, we can be confident that soil samples collected in Ontario are representative. Or are they? Method 5035 is not a failsafe. Improperly used, VOC losses will still occur.
For example, upon opening a soil sample liner, it is critical that the soil sample for laboratory VOC testing is collected very quickly to limit VOC losses. In addition, field protocols call for the sample technician to “swirl” the methanol in the soil sample vial to bring the methanol in contact with the VOCs in the soil sample. Our observation of other consultants’ field sampling technicians is that this step often does not occur. If not conducted, this can result in the loss of VOCs.
Many laboratories supply cut-off syringes to be used to collect the soil sample (cheaper option than commercially-available, core-plug soil samplers). The method employed by many field sampling technicians is to push the cut-off syringe into the soil “with the plunger withdrawn” or “in the full position.”
When using this technique in sandy soils, the cut-off syringe plunger will force air through the soil sample as the syringe is pushed into soil. When using this technique in a clayey soil, the air in the syringe chamber is compressed and will force the syringe back out of soil, thus requiring several attempts to collect a sample. Both situations can result in loss of volatile chemicals from the soil prior to sample collection and preservation.
In addition, some cut-off syringes leave an intact clay soil sample above the level of methanol in the sample vial. This occurs because the syringe being used is narrow and results in a long, soil plug that straddles the level of methanol in an upright vial. Again, this can result in loss of VOCs. Many U.S. states note in their methods that the soil sample must be completely immersed in the methanol.
Regulatory agencies in the U.S. noted that “loss of methanol can cause erroneously high results.” Many U.S. state regulators and laboratories have recognized this pit fall of methanol loss prior to sample collection and have added “methanol level lines” on the sample vial. Additionally, some states are contemplating a post-sampling methanol line on the vial.
You may want to consider oversight or peer review
Finally, it is worth noting that as we are often asked to provide observation on projects (observing another consultant’s work), we have encountered resistance to procedural changes that might help minimize sample collection errors and provide more reliable data.
Senior managers and business owners are making very significant business decisions based on recommendations from environmental assessments. It’s worth the time and effort to make sure the samples are collected properly so the data for the decisions are as accurate as possible.
Do you have questions about site assessment or remediation? Could a
peer review help you avoid a costly mistake? For more information about how Dragun can help you, contact Christopher Paré (cpare@dragun.com)
at 519-979-7300, ext.114