City of San Diego Vertical Benchmarks

[JMS8070]

Hello Surveyors who work in or around the City of San Diego,

I have a question regarding the City of San Diego's Vertical Benchmark Control Book. I'm going through the book (my copy is a PDF from Jan 2008) and finding a lot of NWBPs, NEBPs, SWBPs, and SEBPs. I can figure out the first two letters of the abbreviation, but what does BP stand for? We have heard that it is for the block corners (Block Points?), but unfortunately, we have located several of them in the area we are working and we are not finding a constant for a bench equation.

Some history: this project started outside of the City's jurisdiction so we used County of SD Benches, but now it has moved into the City and they want us to use theirs and I was hoping that we may have already located one of the City's benches.

Thanks in advance for your help.

[Paul Goebel]

I think a BP is a Brass Plug. Be careful with the City BM book. I am working with a committee now that is studying this very subject. The BMs marked with an * in the book have been re-leveled and may not match BMs without an *. I think the difference could be as much as 0.15 feet.

[land butcher]

From info I got ~10 years ago

the first 2 letters are the quadrant the second 2 are brass plug

NWBP means North West corner brass plug.

*in BM desc means these BM's were adj'd in 1970 due to USGS adjmt.
There could be as much as a 0.15ft difference between *BM's and non*BM's

There are probably hundreds of these missing mostly due to HC ramps as the BMs are at the BCR/ECR. One street just north of the Mex border only one of ~20 was still in. Gotta love civic improvements, new Curb, gutter and sidewalk and the area was still crummy.

They are available on a computer file.

[land butcher]

Some history: this project started outside of the City's jurisdiction so we used County of SD Benches, but now it has moved into the City and they want us to use theirs and I was hoping that we may have already located one of the City's benches.

Thanks in advance for your help.

You are going to have a mess. 2 datums for one project.
A company in Orange county did a project that included, County 88 datum, city fullerton 29 datum and caltrans metric. I don't remember who it was, I think they wrote a article in CA surveyor or some rag about the project you might want to find them before you have a real mess.

[Steve Martin]

It looks like you've got your answer.

Brass Plugs set in the top of curb, usually at a curb return.

USGS 1970 adjustment appears to be a typo that has been carried thru way too many years in the City's benchmark book.

It should read USC&GS as it was NGS's predecessor who organized the Southern California Cooperative re-leveling program in the early 1970's

[JMS8070]

Thanks everyone for your responses. As it turns out, I explained to the checker that this project originally started outside of the City and they are fine with the County BMs we cite.

Isn't it great when things work out like they should?

Thanks again!