You should look for the bygdebok for the Verdal area. It might have what you want. "Verdalsboka: en bygdebok om Verdal", 6 or more volumes by Einar Musum; Øystein Walberg.
There is a Sand farm at Verdal, and Sandsvald could have been just a small croft under that farm. I am not able to find any place by that name in the 1865 or 1900 census, but that does not mean that such a place did not exist. What is your source connecting the name to Verdal?