The Hammers have agreed a fee with Leeds for the Dutch attacker and he has been undergoing his medical with the club.
Summerville came through the first part of his medical on Thursday and was then in the process of completing it on Friday morning.
However, there has been some concern about the lack of an announcement from West Ham about the deal being complete, which has led to swirling speculation.
The deal though does remain on track and Summerville is in line to become a West Ham player.
He was the Championship Player of the Season last term at Leeds and made a big contribution towards the Whites’ promotion push.
Summerville’s form dipped towards the end of the campaign though and he scored just three times in Leeds’ final nine games.
The Dutchman also failed to help Leeds break down Southampton in the playoff final and was brought off in the second half.
