6.9　Survey for Sections of Tower Foundations and Topography of Tower Locations

6.9.1　Where required by the design，the sections of tower foundation in four directions from the tower location center to the leg foundation center shall be surveyed and the sections of tower foundation shall be mapped.Sections of tower foundation should be bound into volumes and the words of"Sections of Tower Foundation"shall be indicated on the cover.The sections of tower foundation should have a longitudinal and horizontal scale of 1∶200.For the sample of sections of tower foundation，refer to Appendix K of this code.

6.9.2　For 660kV or 750kV overhead transmission lines，the surveyors shall survey the topography at tower locations and develop topographic maps as required by the design.The topographic maps of tower locations should be bound in volumes，and the words of"Topographic Maps of Tower Locations"shall be indicated on the cover.The coordinate system，elevation system，contour interval，and survey time for the topographic maps shall be indicated.The scale for the topographic maps of tower locations should be 1∶200.For the sample of topographic maps of tower locations，refer to Appendix L of this code.

6.9.3　Total station or RTK GPS may be used for the survey of sections of tower foundation and the topographic maps of tower locations.

6.9.4　The sections of tower foundation shall be surveyed in such a way that the elevation changes in the direction of tower legs shall be reflected and the precision tolerance of elevations at a section point shall be 0.3m.The scope of survey shall satisfy the requirements in the Survey Specifications or be determined by the design personnel.

6.9.5　The topography at tower locations shall be surveyed in such a way that the terrain and landform at tower locations are reflected，and important surface features such as drainage ditches，scarps，houses，and ponds are covered.The scope of survey shall satisfy the requirements in the Survey Specifications or be determined by the design personnel.For the position of a topographic point，the precision tolerance of elevation shall be 0.3m，the distance between two survey points on the maps shall not exceed 3cm，and the contour interval may be 0.5m or 1.0m.

6.9.6　For the topographic maps of tower locations，a coordinate system which is independent or the same as that of the lines shall be selected，the elevation system should be consistent with that of the lines，and relative elevation may be used.