EPA & USGS DEFINITIONS OF EFFECTIVE SOLUBILITY

    EPA - U.S. Environmental Protection Agency

USGS - United States Geological Survey

         SOURCES:

  "Effective Solubility Assessment for Organic Analytes in Liquid Samples, BKK Class 1  Landfill, West Covina California 2014-2016  USGS Open-File Report 2019- -1080"

    "EPA  Ground Water Issue  Dense Nonaqueous Phase Liquids  March 1991" 

Page 8  EPA      

                         "Organic compounds are only rarely found in ground water at concentrations approaching their solubility limits, even when organic liquid phases are known or suspected to be present. The observed concentrations are usually more than a factor of 10 lower than the solubility presumably due to diffusional limitations of dissolution and the dilution of the dissolved organic contaminants by dispersion. This has also been attributed to:  reduced solubility due to the presence of other soluble compounds, the heterogeneous distribution of DNAPL in the subsurface, and dilution from monitoring wells with long intake lengths."

Page 2  USGS

                           "...the presence of DNAPL or mixed DNAPLs was considered unlikely based upon measured concentrations below the aqueous solubility threshold of 1 percent that is commonly used as a "rule of thumb" to screen for the presence of DNAPL, as described in the Draft Leachate Investigation Report ..."

"However, the 1- percent threshold for considering groundwater concentrations indicative of NAPL presence refers to effective solubilities rather than aqueous solubilities, when the NAPL may contain more than one compound ."

    Personally I have been aware of the difference between Aqueous or Lab Solubilities and Effective Solubilities for at least the last twenty-five years. So have Conestoga Rovers and GHD and any other "experts" in the field. Oddly none of them spoke up at last Thursday's TRAC meeting as Allan Deal (GHD) verbally misrepresented the 1 % rule of thumb by suggesting that concentrations at or above 4,900 ppb (ug/l) were required to indicate DNAPL presence. 

I think Sandy that either your "experts" are no such thing OR they find it beneficial not to criticize or dispute Lanxess and their client driven consultants. Keep on appointing polite, deferential people who will never say BULLSHI*  even when they're up to their necks in it.

Alan Marshall  EH-TEAM & more