The Empire State buildings base is almost 2 acres x 443.2 m tall and a square km is 247 acres. 2 * 443m * 37 million / 424 million (424,000 thousand) / 247 ~= 0.3m so covered to the depth of 1 foot. Which seems more reasonable.

ED: Ahh, they had wrong area for California. It's 424,000 square kilometers not "424,000 thousand square kilometers"

That 424million should be 424,000, so we are back at 300m deep. Except the ESB doesn't fill anywhere near all of the (2 acres x 443m) cuboid, so 100m is closer.

Yea, I was thinking they where off by 1000 somewhere. Checking https://en.wikipedia.org/wiki/California gives (423,970 km2).

And yea, 1/3 of the volume is a better approximation but the numbers where so far off that seemed less useful.