Tarp Testing Guidance
How to Test Tarps and Submit Data to EPA
The American Society for Testing and Materials (ASTM) and EPA have developed a standard for tarp testing titled ASTM Standard E2945-14. When this guidance is used to test soil fumigant tarps and the resulting data is submitted, EPA may add the tarps, as appropriate, to either its tarp credit webpage and/or dimethyl disulfide (DMDS) tarp webpage. EPA highly recommends following these testing procedures as closely as possible. Since the reactivity, stability, and other chemical properties are different for each fumigant, the permeability of each fumigant through a film will be different. To assess comparability with existing permeability data, EPA also recommends conducting individual tarp permeability tests for more than one fumigant.
Tarp Testing Protocol
Information to Submit to EPA
A) Description of tarp tested:
- Tarp manufacturer
- Tarp name/designation
- Tarp material
- Tarp thickness
- Other relevant descriptors or technical specifications
B) Test substances:
- Test fumigants (% purity)
- Other additives or solvents mixed with test substances
- Description of test cells, including details of any modifications
- Analytical instrument(s) used, including instrumental parameters (e.g., manufacturer(s), column, detector, etc.)
D) Test conditions:
- Test cell temperature
- Test cell humidity (if other than ambient)
- Testing protocol, including fumigant volumes/concentrations, sample collection schedule (number of samples, sample collection intervals, test duration), number of replicates
E) Test notes:
- Description of deviations and modifications from the written procedure
F) Test results:
- Calculated mass transfer coefficients from individual tests, including graphs.
- Averages and standard deviation of all replicates should be tabulated.
- Compound concentrations or corresponding peak response at each sampling interval, supported by chromatograms.
- Percent recovery of each compound at each sampling time (sum of source and collection chambers relative to the total amount applied).
- Analytical instrument calibration data.
How to Submit Tarp Data to EPA
Please submit the following documents by e-mail to Tiffany Green at email@example.com.
- A cover letter that indicates the tarp(s) and fumigant(s) tested.
- A PDF file containing the information described under Information to Submit to EPA.
- If the file is too large to email, please send by mail to Tiffany Green and Thuy Nguyen at the following addresses:
Background on EPA Tarp Testing
During EPA’s reregistration of the soil fumigants, the use of tarps (i.e., high barrier films) was identified as one agricultural practice that can reduce fumigant emissions. EPA began testing commonly used agricultural tarps to determine how effectively each tarp reduced fumigant emissions. EPA's laboratory tarp testing method, discussed above, was adapted from a method previously developed by Sharon Papiernik and Scott Yates of USDA ARS (Papiernik et al., 2001, 2002). For more information, please see:
- Second Update To Health Effects Division Recommendations for Good Agricultural Practices and Associated Buffer Credits, EPA, January 11, 2011
- Evaluation of the Permeability of Agricultural Films to Various Fumigants, Environmental Science and Technology, October 5, 2011
Current labels for the soil fumigants chloropicrin, methyl bromide/chloropicrin, chloropicrin/1,3-dichloropropene, and metam sodium or metam potassium contain a link to EPA's Tarps webpage. This page lists tarps that qualify for buffer zone reduction credits based on testing using EPA’s method. In addition, tarps are required for use with products that contain dimethyl disulfide (DMDS). The Agency’s DMDS tarps webpage lists the tarps that are approved for use with these products.