3506B24 Final Report

The majority of the fuels burned at Fort Gordon were 2-3 year rough of pine needles, leaves, and woody debris with small contributions from wire grass. Only the fuel burned at TA49 on March 12 was 5 years old. Most flaming periods lasted between 3 and 4 hours, except for the biggest burns on January 8 (12 h), February 13 (6 h), and March 12 (6 h), whereas the smoldering lasted between 4 and 24 h. At Fort Benning, the fuel typically was 3 year rough with mainly pine needle accumulations and less grass than at Fort Gordon. The forest floor was occasionally littered with logging slash and log decks, representing 1,000 and 10,000 h fuels prone for excessive smoldering, especially where timber harvesting had occurred.  In most cases the flaming seized after ~3 h, except for the largest burns, which flamed up to 6 h. Most smoldering phases lasted between 5 and 8 h, only the burn of TA A07 on March 27 visibly smoldered still more than 24 h later. Although the total area burned was only 244 acres, this TA contained sufficient 10,000 h fuels to smolder almost 2 full days after the active flaming phase. At both Forts, the flaming front typically moved at a speed of 150 to 200 acres/h, which will be considered in the emission rate estimates later on.

The following is an analysis of the whole-air canister (grab) sample measurements made to characterize the emissions from the flaming stages of the prescribed burns, and to compare them with emissions from the smoldering phases. Above Table 10 lists all 42 VOC species that were analyzed for the total of 92 can samples taken between February 3^rd and April 30^th 2003. In addition to the above VOC species, all samples were also analyzed for [CO], [CO₂] and [CH₄]. Note that ethyne (acetylene) and 1,3-butadiene (potential carcinogen) were grouped under the alkenes category, although they belong to the family of alkynes and dienes, respectively. Average VOC concentrations for the various sample locations and times are discussed below. The larger statistical uncertainty due to the smaller amount of samples collected in the Fort Gordon, Augusta area (30 vs. 61 at Fort Benning) has not been quantitatively considered in the following data comparison. In order to quantify emissions from this type burning sources, the background concentration levels have to be examined first.