Go check your SFEC document. Page 44, 7.12 FOAM EQUIPMENT suggest that in areas with an RCR or Hazmt or High Structural Threat, group B Class (AFFF or ATC) foam stocks should be atleast 500L.
Do you know how many RFS brigades are CABA trained? There are 70,159 RFS volunteers and a mere 1,935 CABA operators...