Purpose of the present article is to introduce an unused analyze methodology for excavation of surge tank enlargement of HEC MATKA1. Paper exposes the explanation of the way which combines the analyzing methods of non-continual and continual media. The information about existing geological and geotechnical properties presents for the numerical and analytical analyses as a basis. Several results from the stability analyses of structural controlled instabilities during the excavation of water tank are also given. The newly secondary stress-deformation state as a result from enlargement (excavation) is analyzed with program Z-SOIL. The analyze of newly secondary stress-deformation state, which is the result from enlargement (excavation), was performed with Z-SOIL program.