Two more Tesco directors have decided to join chairman Sir Richard Broadbent in departing at the end of this week.The supermarket group revealed that Jacqueline Tammenoms, a six-year stalwart of the retailer's boardroom, had decided to step down at the end of the month.Simultanously, Liv Garfield, also the chief executive of Severn Trent, called time on her stint just shy of two years after taking on the non-executive role.Tesco said Garfield wanted to leave in order to allow her to concentrate fully on her new role at the FTSE 100 water company.Chairman Sir Richard Broadbent, who is also due to leave at the end of the Month, said: "Tesco would like to put on record its appreciation for the dedicated and unstinting contribution of all its directors during a time of unprecedented challenge."Last week the FTSE 100 group confirmed it had appointed Dixons Carphone chairman John Allan as a replacement for Broadbent, who resigned following the accounting scandal last October. The resignations of Garfield and Tammenoms will leave Tesco with only one female non-executive on its board, US turnaround specialist Deanna Oppenheimer.