Analysis - The Institute for Southern Studies

one disposal unit and more than one reported date for initial year of operation, the years were averaged. For example,
if a facility had three disposal units (2 landfills and 1 impoundment) with installation dates of 1970, 1980, and 1990,
this RIA assumed the installation date of all the units was 1980. This assumption simplified the cost calculations on a
per facility basis instead of a per disposal unit basis. If no disposal unit installation data were available, the installation
year is assumed to be equal to the earliest boiler installation year reported in either the 2007 EIA 860 database for that
plant or 1998 EIA 767 database, whichever was older. If no disposal unit or boiler installation year data were
available, an installation year of 1980 was assumed. If the 1995 EPRI Comanagement Survey provided a forecasted
closure year for a unit, new unit installation is assumed to occur in that year. Otherwise, if no closure forecast year is
provided, closure is assumed to occur 40 years after the year of installation (assumed average lifespan for CCR landfills
and impoundments).
New unit construction: The timing of when baseline state regulatory requirements for newly constructed units begin to be incurred depends
on the installation and closure date for the existing disposal units. Baseline state regulatory cost requirements are
incurred at the closure date of the disposal unit when new unit construction occurs. For example, if a plant’s disposal
unit is assumed in this RIA to close in 2019; new unit construction costs required under state regulations are incurred
over its assumed 40-year future lifespan beginning in 2020.
New landfills: The most economic of three landfill options – (1) combination landfill with 50% of waste below
ground and 50% above ground, (2) pile landfill with 5 % of waste below ground and 95% above ground, or (3)
offsite landfill -- is determined within the cost model. The cost for the most economical approach is assigned to
that plant unless available data specify otherwise. The choice is dependent upon on estimated engineering
control costs and annual CCR disposal tonnage.
New impoundments: If currently used as a disposal unit, this RIA assumes a landfill will be constructed as the
future new disposal unit as impoundments reach end of lifespan, because the model calculates that new landfills
are more economical to construct for two cost reasons: (a) if no pre-existing land depressions for use as a new
impoundment, the cost for a larger excavation for a new impoundment rather than a smaller excavation for a
landfill is necessary, and (b) the primary determinant of many of the cost for engineering controls is the footprint
of the disposal unit such that the same set of engineering controls for a new impoundment would be more
expensive than for a new landfill. However, the cost model does not estimate the associated capital and annual
O&M costs for future conversion of existing wet ash and wet scrubber boilers and conversion of wet CCR
conveyance equipment used for moving CCR to disposal units. These conversion costs are estimated separately
outside of the cost model in this RIA.
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