MEMORANDUM 

DATE: June 15, 2007 

TO: File 

FROM: Michael Lowry, RTI 

SUBJECT: Communication with Morton Barlaz and Shannon Bartelt-Hunt 

During the period from July through December 2006, RTI International consulted with Dr. 

Morton Barlaz at North Carolina State University and Dr. Shannon Bartelt-Hunt at the 

University of Nebraska – Lincoln. They provided expert review in support of the Risk-Based 

Landfill Mass Loadings for Solvent-Contaminated Wipes, with primary focus on the 

development and parameterization of the landfill coupled reactor (LFCR) source model. 

The communication was structured around the review of a memorandum1 presenting the LFCR 

model formulation as well as tabular summaries of model input parameters. Conference calls 

were held between Michael Lowry, Dr. Barlaz, and Dr. Bartelt-Hunt on August 22, 2006 and 

November 7, 2006. Additional review of parameter values was received by Michael Lowry at 

RTI on December 9, 2006 via email. 

Dr. Barlaz and Dr. Bartelt-Hunt provided specific advice regarding the following issues: 

• The landfill cell operating life (time period of waste application for one landfill cell) of 

3–5 years is consistent with typical industry practice. 

• The time period before a final cover is installed is consistent with typical industry 

practice in that there is typically a delay before landfill managers install the final cover. 

• The daily cell/lift height describes the thickness of the active waste layer and is derived 

from typical industry practice. 

• The fraction of day without a cover describes the time when waste is being added to the 

active daily cell before the daily cover is applied. Typical industry practice for this stage 

is 8 hours. 

• The daily waste sublayer period describes the time period during which a sublayer of 

waste is added to a daily cell. A value of 1 hour was selected based on professional 

judgment. 

 

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 “Landfill source model comparisons and coupled reactor model formulation” from Steve Beaulieu and Michael 

Lowry at RTI to David Layland at EPA; dated August 14, 2006. 
• In order to accommodate height requirements of the landfill source model (2 ft final 

cover, 2 ft liner, 6 in daily cover, and a minimum lift height of 4 ft), the minimum landfill 

depth was set to 2.9 m, which was approximately the 25th percentile in the distribution 

initially created. This minimum shifted the landfill depth distribution upward, which was 

more consistent with typical operations. 

• The wet density of the waste was assumed to be 0.801 ton/m3. 

• The distributions for waste bulk density and volumetric moisture content were calculated 

based on values of wet density and the gravimetric moisture content typical of municipal 

waste, assuming a water density of 1,000 kg/m3. 

• The waste porosity distribution is typical for municipal waste. 

• The distribution for waste organic carbon fraction is typical for municipal waste. 

• The potential methane generation rate increases as the infiltration rate increases. The 

relationship used in the analysis reflects current understanding. 

The communications with Dr. Barlaz and Dr. Bartelt-Hunt resulted in the following citations in 

the final report: 

Barlaz, M. 2006. “Topics relevant to development and parameterization of the LFCR landfill 

source model.” Phone and e-mail communications from Dr. Morton Barlaz, Professor, 

Water Resources/Environmental Engineering, North Carolina State University, to 

Michael I. Lowry, RTI. July through December. 

Bartelt-Hunt, S. 2006. “Topics relevant to development and parameterization of the LFCR 

landfill source model.” Phone and e-mail communications from Dr. Shannon L. BarteltHunt, Assistant Professor, Department of Civil Engineering, University of NebraskaLincoln, to Michael I. Lowry, RTI. July through December. 

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