Huntley's LNAPL Transmissivity Baildown Test Method Revisited

Baildown tests are an important and relatively inexpensive way to estimate transmissivity. Huntley (2000) developed baildown test analytical methods to determine LNAPL transmissivity. One of his baildown test methods was based on the Bouwer and Rice (1976) rising head slug test method which for brevity we will call Huntley's Method 1. In Batu's (2012) criticism of Huntley's Method 1, he noted that both Lundy and Zimmerman's Method and Huntley's Method 1 are based on the Bouwer and Rice (1976) rising head slug test method, but he observed that only Huntley's Method 1 included a density correction factor. We took a closer look at the derivation of Huntley's Method 1 and found that a mathematical error led to the density correction factor. The corrected Huntley Method 1 equation is equivalent to the Bouwer and Rice (1976) equation for transmissivity. The density correction factor error in Huntley's Method 1 causes the LNAPL transmissivity value to be approximately 4 to 10 times higher than it should be, potentially resulting in unnecessary remediation costs. In light of the error in Huntley's Method 1, it is recommended that the community use the corrected version of Huntley's Method 1. Because Kirkman's (2013) J-ratio baildown test method is based on the uncorrected Huntley Method 1, its use should also be reconsidered in light of our correction to Huntley's Method 1.