Updated: Aug 18, 2021
Recovery Date: Sunday, July 18, 2021
Total Marks Recovered: 18
Discs Recovered: 18
Non-Disc Type Recovered: 0
GPS on Bench Marks Priorities: 1
New Agencies: 1 (City of Coronado)
Keeping it Cool on the Coast
With temperatures on the rise inland, the best place to be this weekend is near the water! Yesterday I spent a leisurely afternoon scouting out survey marks up in Oceanside by the Harbor and the Pier. Today, I decided to head to the other end of the County and look for survey marks on Coronado Island.
But First...GPS on Bench Marks
DO2869: Z 896 RESET (10 km, Priority B-2 Observation)
I have gotten into the habit of checking my map before I leave the house to see if my intended route is going to take me near any survey marks that I've flagged for recovery. This GPS on Bench Marks Priority is located in Mira Mesa just off the 15 Freeway on the San Diego Miramar College Campus. Since it's a Sunday and the campus would be quiet, it was a good time to look for this one.
The "To Reach" description in the datasheet said it was on a concrete water tank, in my mind I envisioned a large above-ground tank/cistern when I didn't see anything fitting that description I parked and headed to the coordinates I'd saved. They weren't really accurate, but I ultimately found it on top of an underground water tank. 🤦🏻♂️ The area was overgrown and I had to clear some debris out of the way to get to it, but it was worth it.
This may rank up there as the disc with the most stamped information on it that I've found to date. It's a U.S. Army Corps of Engineers prestamped survey mark, with the additional stamping:
Z896 RM2 USC&GS 1955 AMS 1962 RESET 2012
A Walk Around the Block
I knew a few things going into today's Survey MArk Scavenger Hunt on Coronado:
The temperature was definitely going to be cooler than Ramona,
Anywhere around the beaches would be insanely busy,
The ALAMEDA station disc was NOT going to be accessible, but I should find a Reference Mark
There is almost literally a survey mark on every street corner!
My plan was to find parking on a side street as soon as I got on the Island, it was pretty easy to find a free and open space in the neighborhood just off 3rd Street. This worked out well because two of my primary recovery targets were the Reference Marks for the ALAMEDA Triangulation Station located just outside the Alameda Gate to Naval Base Coronado and a straight shot down 3rd Street.
I knew that the station disc was a "no-go", it's in the middle of the intersection at Alameda Blvd. and 3rd Street, about 2 feet below the street level, accessible through a standard cast iron manhole cover. First, I don't have the tools to pull a manhole cover (yet) 🤣 and second, I don't imagine anybody would have approved of me stopping traffic in front of the base to pull a manhole cover and look for a survey mark. Just saying... 🤷🏻♂️
While doing my research on the area I came upon a survey report that documented more than 190 benchmarks in the City of Coronado, virtually all of them located at cross streets. I figured I couldn't walk more than two blocks without running into a benchmark!
My day was planned around recovering the reference marks for the ALAMEDA station and then heading over to the old Ferry Landing at Centennial Park to recover Port District GPS Control Point. I just mapped out a big rectangle and decided to see how many benchmarks I could recover along the way.
3rd Street Bench Marks
I've grouped these recoveries by street since they are all basically the same type of mark. I had parked just off of 3rd Street on B Avenue and headed up 3rd towards Alameda Avenue, these were the recoveries I made along 3rd Street. With the exception of the RESET disc for BM 331, these were all set by the same surveyor, Stephen Rodgers Hawxhurst, Lic. No. 7355. All of these marks were in really good shape and tended to be consistently placed. I couldn't find numbers 327 or 330 and it's very likely they were destroyed when the ADA ramps were installed at the intersections.
DC0780: SOUTH RM ALAMEDA
As I mentioned above, the primary station disc for ALAMEDA is about 2 feet below the road surface covered by a standard cast iron manhole cover. Sighting down the arrow on the reference mark, it would appear as if the station is under the closest of the two manhole covers in the intersection, but it's hard to say. I liked these reference marks because instead of being number RM 1 and RM 2, they were identified by their direction from the station, South RM and East RM. This one, the South RM, was completely covered with dirt that was level with the sidewalk (the mark is recessed about three-quarters of an inch, had I not known it was there, I would have easily walked right past it. I could not locate the East RM. Based on the coordinates, distance from the station, and the "To Reach" directions in the datasheet I believe it has either been destroyed or more likely it has been covered up by a sidewalk extension in front of a private residence.
1st Street Bench Marks
I had better luck finding all of the marks on 1st Street, I thought about going all the way to the end to recover 301 and 302, but I'll pick those up when I go back to do 2nd & 4th Streets. These were "more of the same" like those I found earlier. However, I ran into many more that were on red curbs and had been painted over, fortunately, I had my pocket knife and I was able to cut/peel the thick curb epoxy off of the discs...some were easier than others. 🙄
I did find one mark that was issued by a different surveyor, Clive John Hopwood, Lic. No. 6800, it must have been a replacement for 307 as it was stamped 307 A. It's possible the original mark had been destroyed and this was the reset.
SDUPD 030 GPS CONTROL
My main goal on 1st Street was to find this Port of San Diego GPS CONTROL disc in Centennial Park. It was an easy recovery from the perspective of locating it as it was right out in the middle of the sidewalk. The challenge was prepping and photographing the mark WITHOUT photo-bombing a wedding photoshoot (or getting them in MY pictures) 🤣 There were a couple of little kids in the wedding party watching me intently the whole time, as I finished up and walked away, I looked back and they were squatting down pointing at the freshly chalked mark!
Centennial Park was the original site of the Coronado Ferry Landing and was in operation from 1886 to 1969, the booth in the third picture in this set is the original ticket booth. The ferry comes and goes from its present landing pier about 600 feet east of Centennial Park.
I used to ride my bike from Balboa Park, downtown, through National City, Chula Vista, Imperial Beach, back to Coronado proper via the bike path on the Strand, and then take the Ferry back across to downtown, then pedal back up to the Park, a nice ride indeed. 🚴😊⛴
4th Street Bench Marks
Haha, this really was an afterthought! I had recovered 14 of the Coronado Benchmarks, all in the 300 range of numbers, I had to make it 15 and I wanted one in the 400 range 🤷🏻♂️ so I jigged over a couple of blocks and picked up BM No. 452.
This was a great way to spend the day and beat the North County Inland heat, I will likely go back and see how many of the Coronado Benchmarks I can find, I do know that there are a couple of different styles of discs based on the surveyors who set them. With so many of the same basic marks, I will probably set up a separate gallery on my website to showcase the full collection, much like I have for the REI Survey Marks. They all made today's article because of the novelty of literally finding a mark on almost every corner.