Table 7: Summary of Diffusive Sampling at Each Service Station

Site Location Distance from Pumps (m) Concentration Range (ppb) Concentration Mean (ppb)
Service Station A
Site 1 5 3.8 - 5.7 4.8
Site 2 4 2.0 - 7.1 4.9
Site 3 3 6.1 - 9.2 8.0
Site 4 N/A 3.8 - 9.6 7.2
Site 5 N/A 1.2 - 2.8 2.2
Site 6 N/A 1.5 - 8.2 4.3
Service Station B
Site 1 3 1.8 - 5.5 3.9
Site 2 4 1.0 - 2.5 1.6
Site 3 10 1.7 - 3.6 2.5
Site 4 N/A 2.0 - 4.0 2.9
Site 5 N/A < 0.3 - 2.8 1.8
Site 6 N/A 1.0 - 1.7 1.4
Service Station C
Site 1 10 1.5 - 4.3 2.7
Site 2 5 1.4 - 3.9 2.3
Site 3 5 1.8 - 3.9 3.0
Site 4 N/A 2.3 - 3.5 2.9
Site 5 N/A 1.2 - 5.9 2.7
Site 6 N/A 1.1 - 2.7 1.8
Service Station D
Site 1 12 3.7 - 8.6 5.6
Site 2 15 2.1 - 6.4 3.8
Site 3 12 3.3 - 5.3 4.6
Site 4 N/A 10.0 - 20.4 15.6
Site 5 N/A 2.2 - 4.6 3.4
Site 6 N/A 1.8 - 3.9 2.9
Service Station E
Site 1 12 1.7 - 3.7 2.5
Site 2 15 3.7 - 11.7 6.0
Site 3 5 1.6 - 3.6 3.0
Site 4 N/A 4.3 - 7.2 5.8
Site 5 N/A 2.6 - 7.2 3.8
Site 6 N/A 3.7 - 6.1 4.7
Service Station F
Site 1 7 1.3 - 3.6 2.4
Site 2 12 1.4 - 4.7 3.1
Site 3 7 0.9 - 4.3 2.3
Site 4 N/A 2.0 - 18.0 8.2
Site 5 N/A <0.3 - 3.0 1.6
Site 6 N/A 1.0 - 2.8 2.1
Site Location Distance from Pumps (m) Concentration Range (ppb) Concentration Mean (ppb)
Service Station G
Site 1 10 0.7 - 3.6 2.2
Site 2 25 0.7 - 3.2 2.1
Site 3 15 1.4 - 5.4 4.2
Site 4 N/A 1.1 - 11.7 7.9
Site 5 N/A 1.2 - 5.4 3.6
Site 6 N/A 0.9 - 9.6 4.7
Service Station H
Site 1 7 1.3 - 2.2 1.7
Site 2 4 2.8 - 8.2 4.4
Site 3 13 1.5 - 3.4 2.3
Site 4 N/A 5.0 - 13.6 7.9
Site 5 N/A 2.1 - 3.5 2.6
Site 6 N/A 1.3 - 5.0 2.9
Service Station I
Site 1 5 1.4 - 6.4 3.8
Site 2 12 1.2 - 4.3 3.4
Site 3 20 1.2 - 3.9 2.9
Site 4 N/A 2.3 - 11.4 6.1
Site 5 N/A 0.4 - 4.6 2.7
Site 6 N/A 1.3 - 3.4 2.6
Service Station J
Site 1 10 2.3 - 7.5 4.5
Site 2 12 3.2 - 9.3 7.0
Site 3 7 3.9 - 5.7 4.6
Site 4 N/A 9.9 - 26.6 19.1
Site 5 N/A 2.4 - 5.0 3.5
Site 6 N/A 1.7 - 4.6 3.1
Service Station K
Site 1 12 3.6 - 12.5 6.6
Site 2 10 5.0 - 10.0 7.4
Site 3 5 3.9 - 7.1 5.2
Site 4 N/A 4.4 - 19.6 11.1
Site 5 N/A 2.1 - 3.9 3.1
Site 6 N/A 2.4 - 3.1 2.8
Service Station L
Site 1 10 1.2 - 2.7 1.9
Site 2 10 1.2 - 2.7 1.9
Site 3 10 1.2 - 1.9 1.5
Site 4 N/A 2.8 - 5.9 4.8
Site 5 N/A 0.7 - 1.4 1.2
Site 6 N/A 1.5 - 2.8 2.3

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Site prepared by the National Environmental Technology Centre, part of AEA Technology, on behalf of the UK Department of the Environment, Transport and the Regions