Quantifying Uncontrolled Landfill Gas Emissions from Two Florida ...

3.1.4 Summa Canister Sampling
Summa canister samples were collected from the gas collection header pipe in triplicate at Site
#1. These samples represent a composite of LFG from the entire site. Samples were collected
upstream of the vacuum pump to minimize loses and contamination. Blanks were also collected
using a nitrogen gas stream to purge the VOST train condensers and glassware. Samples were
analyzed using Methods TO-15, 25-C, a C1 through C6 alkane hydrocarbons analysis by
GC/FID, and a permanent gases (O2, N2, CO2) analysis by GC/TCD. Results are presented in
Tables 3-9 through 3-11. TO-15 results are qualified using results from the nitrogen blank. Any
compounds reported in samples that are less than 5 times the concentration found in the blank are
considered to be non-detects and qualified “UB”. As specified in the National Functional
Guidelines for Organic Data Review (October 1999) compounds reported in samples that were
less than 5 times the concentration found in the method blank were considered to be non-detects
and qualified “UB”. In computing averages, when all measurements are ND, the average is
reported as ND. When one or more measurement is above detection, the ND measurement is
treated as 50% of the stated MDL. Though not applicable here, the method further specifies that
If MDL is not reported, a ND measurement is treated as zero.
The average gas concentration values shown in Table 3-9 were corrected for air infiltration that
can occur from landfill gas sample dilution and air intrusion into the landfill. The corrections
were performed on the following formula provided in the U.S. Environmental Protection Agency
document, Compilation of Air Pollutant Emission Factors, AP-42,Volume 1: Stationary Point
and Area Sources, 5 th ed., Chapter 2.4 (U.S. EPA, 1997).
where:
C x (1x10 6 )
C P (corrected for air infiltration) = P
C CO + C CH
2 4
CP = Concentration of pollutant P in LFG (i.e., NMOC as hexane), ppmv;
C CO2
Q CH4
= CO2 concentration in LFG, ppmv;
= CH4 Concentration in LFG, ppmv; and
1 x 10 6 = Constant used to correct concentration of P to units of ppmv.
3-13