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.