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 Univer sity and Dr. Shannon Ba rtelt-Hunt at the University of Nebraska – Lincoln. They provide d 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 memorandum 1 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 paramete r values was received by Michael Lowry at RTI on December 9, 2006 via email.

Dr. Barlaz and Dr. Bartelt-Hunt provided sp ecific 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 inst alled 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 appl ied. Typical industry practice for this stage

is 8 hours.

• The daily waste sublayer period describes th e 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.

1 “Landfill source model comparisons an d 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 requirement s 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 approximate ly the 25th percentile in the di stribution 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/m 3

.

• The distributions for waste bulk density and vo lumetric moisture content were calculated based on values of wet density and the gravim etric moisture content typical of municipal waste, assuming a water density of 1,000 kg/m 3

.

• The waste porosity distribution is typical for municipal waste.

• The distribution for waste organic carbon fract ion is typical for municipal waste.

• The potential methane generation rate increase s as the infiltration rate increases. The relationship used in the analysis reflects current understanding.

The communications with Dr. Barlaz and Dr. Bart elt-Hunt resulted in the following citations in the final report:

Barlaz, M. 2006. “Topics relevant to developm ent and parameterizatio n of the LFCR landfill

source model.” Phone and e-mail communicatio ns from Dr. Morton Barlaz, Professor, Water Resources/Environmental Engineeri ng, North Carolina State University, to Michael I. Lowry, RTI. July through December.

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

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

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