How do I, if possible, find benchmark data for Refernece Marks on the FIRM maps.
Thanks in advance RRain
Do you have an example FIRM panel in mind?
In Florida, you can use LABINS to hunt down a lot of state related info.
The last map I downloaded (Essex County, NJ, three days ago, map dated June 4, 2007) had the following in "Notes to Users", on the upper left side of the page:
"To obtain current elevation, description and/or location information for benchmarks shown on this map, please contact the Information Services Branch of the National Geodetic Survey at 301 713 3242, or visit their website at www.ngs.noaa.gov."
My understanding was that "reference marks" have been done away with as a category, and that only NGS BM's will be used from here on in.
The description, location, and elevation are printed on each map. If there aren't any listed you have to go to the adjoining map.
Most of the newer maps I've seen no longer have the reference mark
information on them. One of the reasons I don't throw out older FIRM's.
But the older RMs are now invalid... superseded by the new maps.
In Okie they are on the map panels but we surveyed all of ours several years ago and found that nearly 80% of the RM's had been destroyed.
We have two classes in SW Oklahoma. RM (reference marks) which were spikes in power poles, chiseled squares in curbs and such. Almost all gone and not reliable in the first place from our leveling. Not sure when they were set as no one has seen a FEMA crew doing the work. 60's or 70's maybe.
The MRM's (Master Reference Marks) are generally NGS or ODOT marks on the old fema maps. These are mostly still available.
Before I left we added a few dozen of our marks into the new DFIRMS in our area. They appear in the digital stuff but not on the hard copy maps yet.
Thanks for all of the responses I ended up using two City of Jacksonville BM's.
RRain
You can get the data sheets from the NGS site for your County. Attached is the link and an example. In my County in California, the FIRM bench mark reference number can be looked up on the NGS site to obtain the appropriate data sheet,
