Evaluation of the ecological impact of Class A firefighting foams, applied via Compressed Air Foam Systems, on New South Wales soils

Firefighting foams are categorised based on their composition and use into two classes: Class A and Class B. Previously, Class B foams were widely used in extinguishing fires involving flammable liquids, however, many Class B foams contain fluorinated compounds and have since been deemed detrimental to the environment and human health (Department of Environment and Heritage Protection 2016). As a result, there has been a recent push to utilise Class A foams over Class B foams, however the ecological effects of the use of Class A foams, particularly in NSW, has not been fully determined. The ecotoxicological and microbial effects of two Class A foams, ‘foam 1’ and ‘foam 2’, in three NSW soils were studied. The foams were applied as a foam/water mixture with a v/v concentration of 0.4% foam. This represented the foam concentration commonly employed in Compressed Air Foam systems (CAFS), which is a technique used for the generation and application of foam for firefighting purposes. The effects of exposure to these foams in the three different NSW soils were evaluated at three different lengths of exposure – freshly exposed (day 0), 7 days of exposure and 30 days of exposure. The experiments were conducted under controlled laboratory conditions and ambient outdoor conditions. The effects of germination and growth of Latuca sativa and Triticum aestivum as a result of exposure to foam 1 and 2 under these conditions were evaluated. The results of testing utilising Latuca sativa were invalid, however testing utilising Triticum aestivum indicated no significant inhibition of emergence of growth in seedlings as a result of exposure to the two Class A foams. The effect of exposure to foam 1 and 2 on the behavior of Eisenia fetida/Eisenia Andrei was evaluated utilising controlled laboratory conditions and the same lengths of exposure (0, 7 and 30 days). Avoidance was observed for foam 1 in one soil type, however no behavioural changes were observed in any other foam or soil combination. The observed avoidance for foam 1 in the one soil can therefore not conclusively be linked to the application of foam. Changes in microbial activity in the three NSW soils as a result of exposure to foam 1 and 2 at day 0 and day 30 were evaluated. No significant inhibition of microbial activity was detected in any soil/foam combination. The results of this study indicate no significant ecotoxicological or microbial effects on a variety of soil systems as a result of exposure to the two Class A foams