The Indian government’s NPTEL (National Programme on Technology Enhanced Learning) project has started translating many engineering videos and transcripts into Tamil. While not a traditional "book," you can download PDF transcripts of lectures on Surveying and Mechanics of Materials in Tamil.
Study strategy using Tamil PDFs
The most reliable source is the in Tamil Nadu. They provide e-textbooks for various schemes (like the M-Scheme and N-Scheme) that cover essential subjects in Tamil and English. diploma in civil engineering tamil medium books pdf