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City of Oakland Benchmarks
Posted: Thu Apr 13, 2017 4:07 am
by wingding
Does anyone know if the city of oakland is on 88 datum yet ?
Their GIS map has 88 datum contour elevations (based on comparison w/ google earth)
also is there an online method for the benchmarks yet ?
Re: City of Oakland Benchmarks
Posted: Thu Apr 13, 2017 6:42 am
by Steve Martin
The City of Oakland is on the City of Oakland Datum, which is 3' different from NGVD29
Re: City of Oakland Benchmarks
Posted: Thu Apr 13, 2017 6:58 am
by Jim Frame
The City of Oakland is on the City of Oakland Datum, which is 3' different from NGVD29
3.133 below NGVD29, according to
https://bsm.sfdpw.org/subdivision/bench ... planes.htm.
Re: City of Oakland Benchmarks
Posted: Thu Apr 13, 2017 7:11 am
by Steve Martin
We use 3.00' base upon information provided by the City Engineer in 1964.
The EBMUD table dates back to 1976 at least and that is what we have used in Oakland ever since.
Re: City of Oakland Benchmarks
Posted: Thu Apr 13, 2017 7:42 am
by Jim Frame
I'm not arguing -- I rarely work in the area anyway -- but I'll add the attached document dated 1941 (I think) to the mix just for fun. It's a little hard to read, being a scan of a so-so copy I was given decades ago (and annotated by the surveyor I got it from) . The salient part is this: "Oakland city datum was determined as 3.068 feet above mean sea level by C.E. Grunsky, 1911."
Re: City of Oakland Benchmarks
Posted: Thu Apr 13, 2017 9:00 am
by wingding
Thank you everyone
So The city Datum is within a few inches of 88 datum...I'll have to be carefull with that
Re: City of Oakland Benchmarks
Posted: Thu Apr 20, 2017 7:09 am
by PLS7393
So The city Datum is within a few inches of 88 datum...I'll have to be carefull with that
Please don't say your still surveying in inches? Lol.