When we had our 1/4mi waterline run, the crew that did it used the rock dust as backfill. The trench was sawed through mostly solid rock. It was the same crew that ran water lines for the county and local water utility, and that's the same way they did it for them, so I feel like it was probably OK to do it that way with no sand. But that was 2in PVC pipe. Eight years so far and all is ok.
- Jay
- Jay