I should imagine the work being carried out now for taxiway foxtrot is drainage work.
Attenuation tanks will probably have to be fitted and making sure that Glycol from the de-icing area planned doesn't mix with storm water.
Can't see the start of the taxiway being built for several months yet.
The plans can be seen at LBC planning- discharge condition 14 (drainage assessment-phase 2)
Still nothing about alpha extension though!