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See the FAQ part about the Elevation:
PGC does not do manual changes to elevations, if it is quite off. But weird thing is that the SRTM1 reports positive elevation (71 m) as well as SRTM3 (74 m), as well as OpenElevation (54m) so the question is where does the data really come from.
One possibility might be to try to refresh that cache, through the self-support (I just submitted the cache) or wait for administrator to check the source of this information.