Debasis Naphtha tanks are normally designed with foundation supports on piles with mat concrete base over piles. For Clay soils this will be the normal foundation design for tank farm areas.. Mat-concrete would be provided above the piles. It is not clear how you are observing / getting water just 7" below the sample bottom plate cuttings. This can happen, i guess- if the entire foundation ie., piles and mat-concrete are submerged in water due to flooding in heavy rain monsoon conditions. Such water stagnation and flooding may not occur only to a particular naphtha tank. I guess that it should be there in the entire tank farm areas affecting the other tanks as well. Did you observe such flooding in the tank farm areas in heavy rain conditions? Water flooding may affect the pile conditions over a period of time if this happens recurrently during heave monsoon time. Local rectification of sample cut - patch plate with lap welds facing the top of the bottom plate - ie., the lap weld done at the top of the bottom plate segement faces the top roof (not at the bottom plate welds facing the mat concrete foundation)may not relatively affect the integrity of the tank. Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd India Sept 6 E-mail:nishi@vsnl.com >During rehabilitation of Naptha Tank Bottom Plate while >curtting Bottom Plate coupons to assess plate and soil >conditions in most of the cuts we are getting simple water >at around 7" below the soil front. Now the question is under >real practical perspective if I allow the water to remain >there and perform my bottom plate rectification jobs will it >really harm the integrity of Tank as a whole ? >regards >DM