Grouping by continuous dates

[#1]

Hi !
I have a table like this:

Step	Start	End
Step 1	16/06/2013  09:01:43	16/06/2013  09:11:17
Step 2	16/06/2013  09:11:17	16/06/2013  09:16:29
Step 3	16/06/2013  09:16:29	16/06/2013  10:47:30
Step 4	16/06/2013  11:05:20	16/06/2013 11:05:45
Step 5	16/06/2013 11:05:45	16/06/2013 11:14:09

In the LOAD process I would like to finish with this:

Time	Start	End
01:45:47	16/06/2013 09:01:43	16/06/2013 10:47:30

Steps 4 and 5 are not selected because they sum less then 15 minutes.
Is it possible to achieve this ?

Thanks in advance !

Regards,
Itamar