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Fact Sheet
SW-846 Method 5035: Closed-System Purge-and-Trap
and Extraction for Volatile Organics in Soil and Waste Samples
What is SW-846 Method 5035?
The United States Environmental Protection Agency’s (U.S. EPA) “Test Methods for
Evaluating Solid Waste” describes procedures to be used in collecting and
preserving samples of waste, soil, sediments, and groundwater. Method 5035,
referred to as the “Closed-System Purge-and-Trap and Extraction for Volatile
Organics in Soil and Waste Samples,” was included in SW-846 as part of Final
Update III. This update was published in the Federal Register on June 13, 1997.
SW-846 Method 5035 identifies procedures to collect soil samples for volatile
organic compound (VOC) analysis. The procedures are outlined in the method’s
Subsection 4.5 (Field Sampling Equipment), Section 5.0 (Reagents), and Section
6.0 (Sample Collection, Preservation, and Handling). The soil samples must be
preserved with one of two preservatives prior to analysis, either in the field
at the time of collection or in the laboratory within 48 hours of collection. A
sodium bisulfate preservative is added to soils anticipated to contain VOCs at
concentrations less than 200 parts per billion (ppb), while a methanol
preservative is used for those soils anticipated to contain VOCs at
concentrations greater than 200 ppb. If the soil samples are to be preserved in
the laboratory, the samples must be collected in a Purge-and-Trap Soil Sampler,
an EnCore sampler, or a similar type device and must then be delivered to the
lab for preservation within 48 hours of sample collection.
Why did U.S. EPA change the method of VOC soil sampling?
Method 5035 more accurately identifies the types and concentrations of VOCs in
soils than the previously used method, which was susceptible to errors due to evaporative losses of
volatiles and microbial degradation prior to sample analysis.
Is SW-846 Method 5035 incorporated into Illinois regulations?
Yes. On June 4, 1998, the Illinois Pollution Control Board adopted amendments to
35 Illinois Administrative Code (35 Ill. Adm. Code) 742: Tiered Approach to
Corrective Action Objectives (TACO). As part of the changes to TACO, SW-846 was
incorporated by reference to include Update III, which contained Method 5035.
Newer Test Method 5035A, which, in part, allows for sample preservation by
freezing, is also included in SW-846.
What remedial programs use Method 5035?
Generally, all Illinois EPA remedial programs using TACO recognize the
importance of Method 5035, including:
Resource Conservation and Recovery Act (RCRA) Program: SW-846 Method 5035 is
required and currently being implemented. Following the procedures listed in
Attachment A of the closure guidance will meet the requirements of Method 5035.
Leaking Underground Storage Tank (Leaking UST) Program: Sites that reported a
release on or after June 4, 1998, and before June 24, 2002, and are classified
as high priority; sites for which the owner or operator elected to conduct
corrective action pursuant to 35 Ill. Adm. Code 732.300(b), 732.400(b), or
732.400(c); and sites that reported a release on or after June 24, 2002, must
use SW-846 Method 5035 for VOC soil sampling. For samples collected prior to the leaking UST site being
classified as high priority, the Illinois EPA recommends the use of SW-846
Method 5035. If the leaking UST release was reported before June 4, 1998, the
owner or operator may use either SW-846 Method 5035 or Method 5030 when soil
sampling for VOCs.
Voluntary Site Remediation Program: The use of SW-846 Method 5035 provides a
more reliable and valid result than previous methods; consequently, the use of
this new method is strongly encouraged.
Will I need new sampling equipment?
The necessary soil sampling equipment is identified in Subsection 4.5 of SW-846
Method 5035 and includes: Purge-and-Trap Soil Sampler, EnCore sampler,
disposable plastic syringes, portable balance, and balance weights.
What labs can analyze my soil samples? What analytical methods must my lab use?
The soil samples can be sent to an accredited laboratory capable of performing
complete VOC analysis using SW-846 methods and able to follow the procedures
identified in Method 5035. Method 5035 may be used in conjunction with any
appropriate gas chromatographic procedure including, but not limited to, Methods
8015, 8021, and 8260.
What happens if the detection limits are above the remediation objectives
established in 35 Ill. Adm. Code 742 (TACO)?
The Illinois EPA recognizes problems may be encountered when preserving soil
samples using sodium bisulfate (i.e., certain soils may react vigorously with
the acid). In these cases, the methanol preservation technique must be
substituted. Since the methanol preservation method is accurate only for
soils with VOC contamination greater than 200 ppb, the analysis of these soil
samples will often not provide evidence that the remediation objectives
established in TACO have been met. The site owner may need to request
alternative remediation objectives under a TACO-Tier 3 scenario.
Please note: The Illinois EPA will require verification from the laboratory that
performed the analysis indicating the soil did react with sodium bisulfate and
only the methanol preservation method could be used.
Will the Illinois EPA re-visit sites that were closed using the previous VOC
methods/procedures?
The Illinois EPA will not investigate sites closed (i.e., No Further Remediation
Letter, 4(y) letter, etc.) using the previous method for VOC sampling and
analysis unless additional contaminants are identified that pose a threat to
human health or the environment.
If I have questions, who can I contact at the Illinois EPA?
The following Illinois EPA representatives are available to answer
program-specific questions concerning SW-846 Method 5035:
Leaking UST Program - Tom Henninger
(217) 782-6762
RCRA Program - Jim Moore
(217) 524-3300
Voluntary Site Remediation Program - Contact your assigned Project Manager or
Greg Dunn at (217) 782-6761.
A paper copy of SW-846 Method 5035 can be obtained through the U.S. Government
Printing Office at (202) 512-1800 or NTIS at (703) 487-4650.
This fact sheet is for general information only and is not
intended to replace, interpret, or modify laws, rules, or regulations.
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