豁免
2022 年 4 月 11 日Roller Compacted Concrete Dam
2022 年 4 月 11 日
NGVD – A vertical datum is a surface of zero elevation to which heights of various points are referenced. The NVGD of 1929 was utilized until it was superceded in 1992 to be replaced with the North American Vertical Datum of 1988 for the contiguous US and Alaska.
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