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Main Page ENVIRONMENTAL CONSULTING Position Paper SPIKES 2ndCOLUMN DUPLICATE

SUGGESTIONS FOR REDUCTION
OF ANALYTICAL COSTS BY
ELIMINATION OF UNNECESSARY
FIELD BLANKS

by Douglas M. Chatham

Senior Chemist

SUMMARY

Many field blanks could be eliminated from environmental investigations by relating the usefulness of the blanks to the project objectives. If the purpose of the project is to discover the presence of contaminants and/or measure the total amount of contaminants in a plume, the blanks are needed to show that the contaminants are sample-related and not introduced from other sources during the process of sampling. If the purpose of the project is to demonstrate that cleanup levels, ARARs, or MCLs have been met, field blanks are not necessary. Elimination of excessive blanks from one project allowed a reduction in analytical costs from $53,500 to $45,700 (14.5%).

RECOMMENDATIONS

Any and all QC which contributes to the quality of the data or are required for other reasons should be included regardless of arguments presented in this paper. For each blank sample proposed, Project Managers (PMs) and Quality Assurance Project Officers (QAPOs) should ask what that determination contributes to the quality of the data and whether it helps meet the project DQOs. If a blank sample contributes nothing toward the DQOs, an argument should be made against incurring the cost for that sample.
For sampling efforts undertaken to demonstrate that ARARs, MCLs, or cleanup levels have been met, eliminate all field blanks.
For projects which require blanks, use the following criteria for determining the frequency and type of blanks to take:
Ambient blanks - Collect only in the event that the field team observes nearby activities that could contaminate VOC samples.
Equipment blanks - Collect rinseates on bailers used to collect groundwater samples. Collect equipment rinseates for each decontamination event. Do not collect rinseate blanks for soil or sediment samples.
Combine blanks (Equipment Rinseate, Ambient, and Trip Blanks) wherever possible. When equipment rinseate or ambient blanks are taken, eliminate trip blanks and ship all sample VOCs in the same cooler as the equipment rinsate blank.
If sampling of multiple types of blanks cannot be avoided, analyze only the equipment rinseate. If a problem is found, then analyze the remainder of the blanks.
If corrective actions are possible, submit source blanks as needed to implement those corrective actions. During long-term programs, submit source water blanks from water purification systems either to a fixed base laboratory or to an on-site chemist to maintain quality control of that system.

DISCUSSION

The field blanks collected at a site could include trip blanks, ambient blanks, bottle blanks, source water blanks, and equipment rinseate blanks. The reason for analyzing different types of blanks is to be able to trace the origin of contamination in order to take corrective action. This requires that the results be available as field work is being conducted. Generally, blank results are not available before the sample results are reported, which can be many weeks after the field effort is completed. A multiplicity of blanks may be justified, but the project manager should develop good reasons for them. Long-term programs involving numerous separate projects could benefit from different types of blanks, since corrective action can be taken between projects. If on-site analytical equipment is available, analysis of blanks on-site would allow corrective action to be taken rapidly and these are generally much less expensive than fixed-base laboratory analyses. On-site analysis of blanks must be conducted with methods which are analyte-specific, have quantitation limits lower than the action levels, and documented calibrations and detection limits. Many of the blanks submitted to laboratories for analysis are probably not necessary.

In many cases, two or more blanks could be combined; e.g., an equipment rinseate blank taken to the sampling site serves as an ambient blank and a bottle blank, and if this blank is shipped in a cooler with VOA analyses, it also serves as a trip blank. Another approach might be to collect a full set of field blanks and analyze only the most comprehensive (the equipment rinsate). As stated by Dr. Keith (1), "Sample analysis is often expensive. Sometimes it is prudent to collect a full suite of blanks but only analyze the field blanks. If the field blanks indicate no problems, the other blanks may be discarded or stored as necessary. If a problem is discovered, the individual blanks can be analyzed to determine its source. Resampling will still likely be necessary."
Data validation guidelines (2) state that if a compound is found in any blank, positive sample results greater than the quantitation limit and less than five times the blank concentration are qualified as not detected (U or ND) at a quantitation limit (QL) equal to the sample result. If this adjusted QL is above the action level, it cannot be used to demonstrate a concentration below the action level. There is no difference between a positive sample result greater than an action level and a blank qualified result with a quantitation limit greater than the action level when the purpose is to demonstrate a concentration below the action level. Thus, if the purpose of sampling is to demonstrate that ARARs, MCLs, or cleanup levels have been met, or for monitoring remediation efforts, there may be no reason to take any field blanks. Since the resulting corrective action (i.e., resampling) based on a sample result above the action level is the same with or without blanks, the blanks probably are not necessary. Elimination of excessive blanks and duplicates from one proposal has allowed a reduction in analytical costs from $53,500 to $45,700 (14.5%).

Types of Investigations

The CERCLA preliminary assessment (PA) and the RCRA facility assessment (RFA) are used to identify any releases or migration from a facility based on the existing information and apparent visual evidence. The PA or RFA are typically the first step in the CERCLA or RCRA process. Samples are not usually taken during these assessments.
The CERCLA Site Investigation (SI) and the RCRA Confirmation Sampling Process (CS) are used to confirm or disprove suspected releases to an environmental medium based on information obtained during the PA or RFA. The SI or CS process is generally limited in scope; the goal is to gather sufficient data to confirm the presence or absence of contamination at Potential Release Locations (PRLs), and to provide a basis for the scope of the CERCLA Remedial Investigation (RI) or the RCRA Facility Investigation (RFI) process or a No Further Action decision. The data quality levels for SIs or CSs are generally required to be Level IV (CLP) or Definitive data (3) since the data is required to be litigation quality. These investigations are usually the first ones conducted at most sites and historical data will be limited or non-existent. The blanks are needed to prove that the contamination found is from the site, but multi-purpose blanks may be justified in many cases.
The CERCLA Remedial Investigation (RI) and the RCRA Facility Investigation (RFI) are used to evaluate the nature and extent of the releases of hazardous waste and hazardous constituents and to gather sufficient data to support the preparation of a risk assessment and Feasibility Study (FS) or Corrective Measures Study (CMS). RI/RFI studies could be screening data with definitive confirmation. These studies are much more extensive than SI/CS investigations. The screening data could be on-site and/or Level II fixed laboratory analyses with 10% Level III or CLP definitive confirmations. Blanks should be based on quality control rather than quality assessment considerations; e.g., monitoring an on-site water purification system to prevent the use of a spent system.
The CERCLA Feasibility Study (FS) and the RCRA Corrective Measures Study (CMS) are used to develop and evaluate a remediation plan or corrective measures alternatives and to recommend the appropriate corrective measure for the facility. FS/CMS studies could be screening data with definitive confirmation. These studies can be as extensive as RI/RFI investigations, but FS/CMS studies are much more focused. The analyses are limited to the analytes of concern which have been well documented in prior investigations. The screening data could be on-site and/or Level II fixed laboratory analyses with 10% Level III or CLP definitive confirmations. Blanks should be based on quality control rather than quality assessment considerations; e.g., monitoring an on-site water purification system to prevent the use of a spent system.
The CERCLA Remedial Design/Remedial Action (RD/RA) and the RCRA Corrective Measures Implementation (CMI) are used to design, construct, operate, maintain, and monitor the performance of the remedial action or corrective measure selected. These studies can be as extensive and focused as FS/CMS investigations. The analyses are limited to the analytes of concern which have been well documented in prior investigations. The screening data could be on-site and/or Level II fixed laboratory analyses with 10% Level III or CLP definitive confirmations. Blanks should be based on quality control rather than quality assessment considerations; e.g., monitoring an on-site water purification system to prevent the use of a spent system.

The basic purpose of cleanup verifications and long-term monitoring is to demonstrate that the concentrations of contaminants are below a mandated level. Blanks are not needed for quality assessment of these studies. Blanks should be based on quality control rather than quality assessment considerations; e.g., monitoring an on-site water purification system to prevent the use of a spent system.

LIST OF REFERENCES

1. Keith, Lawrence H., Ph.D., Environmental Sampling and Analysis, A Practical Guide, Lewis Publishers, Inc., 1992.
2. USEPA Contract Laboratory Program, National Functional Guidelines for Organic Data Review, June, 1991.
3. EPA, Data Quality Objectives Process for Superfund, Interim Final Guidance, p. 42, EPA540-R-93-071, September 1993.
4. EPA, Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, SW-846, 3rd Edition, Final Update 1, November 1990.