The spot was due to subsurface seepage from an irrigation leak, occurring at a PVC fitting. The main 4-inch line had been bent into an S-shape during the initial installation, stressing the cemented fittings.

Eventually a water jet carved a channel, weakening the connection, and a change in pressure burst the weakened piping. The depicts the short-lived repair job. The expensive compression fitting was added in the hope that unaligned pipes could be held together straight, rather than by shortening the tee and digging the main line back to allow slack to get everything square.  In a few years there was another leak in the same spot.

(Translation: ". . . next time you dig a ditch, use a string line.")