Dear sir, 
Please find our comments below                                                                                                                                            1)We can use existing Columns marked as (Y & Z) available at your Site for our System only. 
2)As per our 2D Layout we require Column height minimum 9800 mm (Height of "Z" column mentioned in your drawing is 6000 mm only)
3)Any attached structure & other Loads not considered (except our system loads) on existing columns.
4)You can fabricate same column as per marked as Z (height should be 9800 mm) for new column location mentioned as X
5)Also check our foundation loads w.r.t. existing column foundation loads
6) If you are going ahead with the existing columns then kindly send us the detailed dimensional drawings for columns "Y" & "Z".                                                                                                                                                                Kindly reply with final conclusion to finalize Structure Model & Detailing.
