Long ago I was faced with installing a water line to extend the rural water district's line to my property. The district engineer dictated the material and design. I had to install and deed to the district when completed, inspected and approved. In the process I found that glued pipe was never approved, mainly due to the thermal expansion/contraction of even buried PVC. We were required to use what the local trade calls 'o-ring pipe'. PVC with one belled end with a rubber seal factory installed. But, the supplier had none in stock and delivery was a month or more out. The engineer approved normal pipe, with the belled ends cut off and replaced with normal compression unions. This was 2" but I think the same product(s) are available in 3".
Since gray and white PVC are the same sizes those unions would solve the expansion/contraction issue.