PDFWAC 173-408-980

Appendix I.

1.0 Calculate Heat Input Capacity
Equation 1
 
Where:
 
 
 
Collection Efficiency
=
The landfill gas collection efficiency in percent (%), which is 75 percent.
 
 
 
GHV (Gross Heating Value)
=
Gross heating value of methane, which is 1,0121 in units of British thermal units per standard cubic feet, or Btu/scf.
 
1
Landfill Methane Outreach Program (LMOP) Interactive Conversion Tool
2.0 Methane Gas Generation
CH4 Generation is calculated using the following equation:
Equation 2
 
Where:
 
 
 
CH4 Generation
=
CH4 generated in the inventory year (Mg of CH4).
 
 
 
FCH4
=
Fraction of decomposing carbon converted into CH4 (Default = 0.5).2
 
 
 
ANDOCyear-start
=
ANDOC in place at the beginning of the inventory year.
 
 
 
ANDOCdeposited-last year
=
ANDOC deposited during the previous inventory year.
 
 
 
ANDOCdeposited-same year
=
ANDOC deposited during the inventory year.
 
2
2006 IPCC Guidelines for National Greenhouse Gas Inventories
3.0 To Convert Methane Generated from Mg of CH4 to SCFM
Equation 3
4.0 Define ANDOC%
Equation 4
Where:
 
WIPFRACi
=
Fraction of the ith component in the waste in place.
 
TDOCi
=
Total Degradable Organic Carbon fraction of the ith waste component (Mg of that component/Mg of Total waste in place).
 
DANFi
=
Decomposable Anaerobic Fraction of the ith waste component, that fraction capable of decomposition in anaerobic conditions (Mg of decomposable carbon for that component/Mg TDOCi for that component).
5.0 Define ANDOC
Equation 5
Where:
 
ANDOC
=
Anaerobically Degradable Organic Carbon, carbon that is capable of decomposition in an anaerobic environment (Mg of carbon).
 
WIP
=
Waste in place estimate of all the landfilled waste (wet weight) as reported to Ecology's Solid Waste Management Program (tons).
6.0 Calculate ANDOCyear-end
Equation 6
 
Where:
 
 
 
ANDOCyear-end
=
ANDOC remaining undecomposed at the end of the inventory year.
 
 
 
ANDOCyear-start
=
ANDOC in place at the beginning of the inventory year.
 
 
 
ANDOCdeposited-last year
=
ANDOC deposited during the previous inventory year.
 
 
 
ANDOCdeposited-same year
=
ANDOC deposited during the inventory year.
 
 
 
M
=
Assumed delay before newly deposited waste begins to undergo anaerobic decomposition (Months, Default = 6).
 
 
 
k
=
Assumed rate constant for anaerobic decomposition; k = ln2/half-life (years); half-life is the number of years required for half of the original mass of carbon to degrade.
 
Table 1 lists the accepted constant values for the anaerobic decomposition rate ("k").
Table 1: K Values
K for Average Rainfall (Inches/Year)
Inches Rain
<20
20-40
>40
K Value
0.02
0.038
0.057
[Statutory Authority: Chapter 70A.540 RCW. WSR 24-11-052 (Order 22-15), § 173-408-980, filed 5/13/24, effective 6/13/24.]
Reviser's note: The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency.