Permanent Monuments Help!?

it's best to flare the bottom of the hole, if you just put in a pvc pipe and concrete frost heave will push it right out without something stopping it.

Ha! That's what I was thinking about last week on the way home from work and couldn't remember this morning. Give it the tapered flared edge and that would help some of the heave. Thanks! Do you think if I cut the pipe down to 1 foot and flared it out it would hold or should i stay with the 2 feet and flare that? Thanks again!

> I am looking for some help in how I'm going to do this. For our upcoming projects this year I've decided that I want to create a monument network all throughout the Borough.

I think I'd strongly consider setting brass tablets grouted flush into existing concrete structures such as the tops of curb inlets unless curb inlets are less stable in your climate than I think they are. For the cost of setting just one of the monuments shown in your detail, you could have probably four tablets installed and it seems to me that would be more useful since several nearby marks would provide a ready means of checking the stability of any one.

If you abut a monument to the sidewalk, then next time somebody rips out the sidewalk for utility work, handicap access ramp, or whatever, they will take out your monument to set the new forms.

If you want to use them as elevation bench marks as well as horizontal positions, the bottom needs to be below frost depth and nothing about them should give the frozen ground a feature to grab onto. See the rod and sleeve monuments that NGS sets; the sleeve can slide on the inner rod, as opposed to your drawing where the concrete binds them.

For stability, you want to use the (first priorty) deepest and (second priority) biggest solid object around. Concrete of storm drain boxes would be better than sidewalks or curbs.

> I think I'd strongly consider setting brass tablets grouted flush into existing concrete structures such as the tops of curb inlets unless curb inlets are less stable in your climate than I think they are. For the cost of setting just one of the monuments shown in your detail, you could have probably four tablets installed and it seems to me that would be more useful since several nearby marks would provide a ready means of checking the stability of any one.

Thanks for the insight Kent. This is one of those you do something for us, we do something for you favors from utility contractors and contractors for our projects. Government mentality! The cost wouldn't be an issue in that perspective. We already have the Survey Markers ready as the surveyor before me ordered a full box and never set any.

We use a steel frame and steel hood for our inlets and our curb is never the greatest after a winter. I guess I can go check a project I was first here for 2 years ago and see how that curb has held up. I imagine some shifts may occur.

Thanks for your response and I'll be sure to keep this in mind!

I would not have them precast. Pour them in place with the hole belled out at the bottom. Also, you can recess the disc, but make it so that it is dome shaped and not a bowl. The more steel in the hole, the better.

Honestly, the monument you are describing isn't all that stable. If you precast them, then they tend to slip, but poured in place will grip the ground around it. If this seems like too much work, then I'd suggest Kent's idea as it seems much more stable than the precast version in PVC. The issue is that they may not be in the best spots so it's a tradeoff.

> I would not have them precast. Pour them in place with the hole belled out at the bottom. Also, you can recess the disc, but make it so that it is dome shaped and not a bowl. The more steel in the hole, the better.
>
> Honestly, the monument you are describing isn't all that stable. If you precast them, then they tend to slip, but poured in place will grip the ground around it. If this seems like too much work, then I'd suggest Kent's idea as it seems much more stable than the precast version in PVC. The issue is that they may not be in the best spots so it's a tradeoff.

I had no intention of them being precast. Everything was to be poured monolithic.

As for them near the sidewalk, that is a good point to not have them up against it directly. Our ROW is from back of sidewalk to back of sidewalk on every road. Some places have grass plots usually 5 feet wide, but this is where your utilities come into play. The GAS likes to be under the sidewalk and water is in the grass plots. I figured tucked up by the sidewalk should be the best option for placement.

Kent has a point

(and it's NOT at the top of his head 😉 )

Try and fix your control monuments upon or to existing appurtenances. For example, the fire plug in my front yard was placed in 1921, the pavement in the street has been replaced twice in twenty years.

Over the years I have set a number of different types of concrete posts in the ground. Some have lived, most have not. I have seen "permanent" concrete monuments go away a lot quicker than one might imagine in an urban setting. Find someplace that hasn't changed and may not change for a while. Public Parks are a good bet.

If you're dead set on a hole, the only monument I've seen that has a chance of survival is the NGS standard stainless steel rod driven to refusal. The rods usually make it, although the access box can suffer quickly if there's humans around.

Put your monuments in boxes in the street just like water valve boxes except with MONUMENT on the cast iron lid.

Walks get torn up every time ADA changes.

The boxes are best because contractors are used to protecting them and bringing them up to grade when the street is repaved.

The challenge is getting the City Engineer to pay for them. "But those cost $3000!" I said, "The monuments are the most valuable thing in the street, they control all the property lines in the neighborhood."

> We use a steel frame and steel hood for our inlets and our curb is never the greatest after a winter. I guess I can go check a project I was first here for 2 years ago and see how that curb has held up. I imagine some shifts may occur.

Just a punchmark on the steel frame with an i.d. number stamped beside it might be simple enough.

The scheme that I'd be thinking about is one where there are at least three marks at each intersection, all exposed and easy to locate. They would just have to be something that a prism and target could be set up on, not necessarily chosen to be occupied with instrument.

A surveyor would lay out a temporary control point in some convenient location and position it by resection from the nearby marks. That would get temporary control in places where setting permanent monuments might be difficult and also check the stability of the marks in the process.

If old curb lines are fairly straight, then maybe they are fairly stable horizontally, if possibly not vertically.

Kent has a point

As for fire hydrants, the ones in the north usually have the nut to turn them on at the top, which might seem like a good place to make a punch mark. Until you remember the firefighters will turn the nuts on fairly often, and when they are done, the angular position of the nut will not necessarily be the same.

Kent has a point

We've heard some horror stories about fire hydrants. They are quite unstable vertically, perhaps slightly so horizontally, and do sometimes get replaced. If you use one, you should pick (or mark) a unique place on the body and not on any movable part.

I have GNSS control monuments along Forest Roads in open areas which are always in danger of being bladed out when they clean up the road for the next harvest. I bury them sometimes.

I had an idea of doing what you suggest. Set 3 rebar/cap reference monuments at each one back in the woods. That way if the main monument gets taken out a new one could be set and resected off of the three reference monuments. Generally monuments survive better in the trees but they aren't conducive to GNSS observations in there.

Permanent Monuments Suggestions

Place at GPSable points, staying away from tree easements, gas, water and electric service lines. Also stay far enough away from handicap accessible areas. Especially if they have yet to be installed or repaired.

I work in one township that has a small marker embedded in the center of the curb over each sanitary lateral. If possible I use them for traverse and/or GPS points. Where the lots do not match frontage on each side of the street the mark on the opposite side of the street has a good chance of giving me a sight to the PQ back yard.

If you have such markers, green dots on curbs are pretty easy to find, make sure you use them for your monument ties.

Paul in PA

fire hydrants

I avoid hydrants like the plague, they are not stable. I used it for an example.

My original point was an example that some infrastructure remains in place for years and some does not. Be smart with what you choose.

Permanent Monuments Suggestions

> Place at GPSable points, staying away from tree easements, gas, water and electric service lines. Also stay far enough away from handicap accessible areas. Especially if they have yet to be installed or repaired.
>
> I work in one township that has a small marker embedded in the center of the curb over each sanitary lateral. If possible I use them for traverse and/or GPS points. Where the lots do not match frontage on each side of the street the mark on the opposite side of the street has a good chance of giving me a sight to the PQ back yard.
>
> If you have such markers, green dots on curbs are pretty easy to find, make sure you use them for your monument ties.
>
> Paul in PA

Thanks Paul. My intentions were to place near handicap structures ONLY new being installed or replaced. Our Street Resurfacing projects we call for utilities to decide if they need to replace their lines as we have a NO-CUT ordinance unless for emergency repairs. So, a newly resurfaced road will have new ADA ramps as our crews replace them on all resurfaced streets. Utilities that mess with sidewalk remove the blocks and replace new. We hope our streets last us 20 or so years and won't need updated until then.

I really like your description of the sanitary lateral marker. Not only am I the 'surveyor' here I'm also the 'Engineer Assistant', 'Inspector', 'Designer', etc. I am out in the field with constructions projects managing them within the Borough than surveying. I also locate for 1call services for our maintained utilities... I really, really like the marker idea, that would make it easier locating then measuring off manhole to manhole. Thanks for that!

I would stay with the 2 feet, the concrete pads will help with frost heave, the soils will tend to be dryer under them, but be sure to grout around your monument, we usually leave them just below the conc elevation, maybe an 1/8" to 1/4" from flush, you don't want them above the pad but not quite flush or snow removal will bung them up.

Thanks. As of right now I have them to be set 1/2'' below top of pipe. This should keep them from being hit by anything. So a 2 foot section of pipe with the flared bottom? Also keeping the rebar at 3 feet or should I make it within the size of the pipe or shouldn't that matter?

I've never set permanent before and want these to be able to be GPS'd and years from now able to recover with ease.

Thanks everyone for your responses, the insight is great!

One advantage of taking almost 40 years to stop in one spot is diverse experience. While I glean a little here and there, monuments vary by geography for a reason.
If you set that monument here it would never stabilize vertically. The bottom would need to be considerably wider. The only monument I can think of that stays put in anything is a FENO or something similar...