Looks like Cardamine sp. It could be the dreadful pest Cardamine hirsuta. https://www.google.co.uk/search?hl=...urce=og&sa=N&tab=wi&ei=1jGJT96APIPT0QWC7oi6CQ
The leaves and the habitat look rather unusual for Cardamine hirsuta. If there is a closeup photo of the plant it might be good to check whether the number of stamens is 4 (as in most cases for Cardamine hirsuta) or 6 (as usual for probably anything else from the genus). The number of stem leaves would be also nice and it would be nice to know whether the plants have a rosette, because my most probable choices would be Cardamine oligosperma or Cardamine flexuosa, which has been spotted in the lower mainland , e. g. in Surrey (see http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Cardamine flexuosa for the distribution map and http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=105607 for a key)
