How Many???

The LAST sewer manhole that I tied in (nearly 40 years ago), took us about 2 hours (it was covered by about 1/2 foot of asphalt and we found it using a dip needle).

🙂
Loyal

Hard to say....do you think they're gonna pop right up?

How deep? Do you need to carry a 25 foot rod (or something longer)? Two hooks and a hammer?

Can't see two men doing it for less than 3 minutes per manhole, under optimal conditions.

Dang! I would allow about 15 minutes each on average. Some will be simple. Some will be dang near impossible. Depends on how many of each kind you encounter plus the depth. How long does it take to do one that is 40' deep?

Do you mean 1/2 hour per manhole? Need to move from manhole to manhole with your tools, sometimes need to search for them let alone the time doing the data collection. I would probably estimate 2/hr unless I knew mor,e about the conditions.
jud

> Can't see two men doing it for less than 3 minutes per manhole, under optimal conditions.

3 min? No way. I could see 15-20 min per. To locate, pop the lid, measure down(s), sketch. No less than 15 per.

Go with 30 with a two man crew- not bolted, visible, covers- and watch out for the ones that dont have an invert- the ones that are FULL:-P
I pooped, I mean popped one of those last month...

I would say that is hard metric to capture.

I will say mostly dittos to every reply thus far.
Me and a buddy got sent out to do this stuff. I made up the
name for us - "sewer crew". Unfortunately it stuck and
we got stuck with said tasks.

and what if the gps is floating and you have to set a pair of tp's and set up the transit? these things can take from a couple of minutes to an hour and that's if you can even find them.

Don't forget to add time for worker's standing around scrathing their a*s waiting to see who's going in the manhole...or to stick rod in said manhole...you know what I'm talking about, "Dude, what the he*l was that floating by"?

I'd send in the bid for X number of grade A manholes, and X number of grade B's etc. then, make up a list of what a Grade A was, all the way to Grade F.

A Grade F requires a back hoe, to get the top off.

A grade G is full of poop, and will require an additional visit, after water has gone down.

Also, I'd get a good mirror, and a great spotlight, to shine down there, to measure inverts, and sizes.

I'd set it up, so that I would not regret getting the bid.

And, so that they could see that not all manholes are the same.

N

My M.O. would be to dip them all, marking the center of barrel, then go back and shoot them all.

I'd guess a 2 man crew could dip about 6 or 8 an hour. Allowing for travel time that might be around 35-50 a day. One man crew could then GPS them at a rate of 10-12 an hour, assuming 300-400 foot walk between each.

I have had over 1200 manholes to inspect one winter. We averaged about 15 a day. some days we did 30, some days we did less than 10. We also made up a manhole inspection sheet, and had a special rod that I made for getting pipe sizes. It had a 12" L bracket attached to it so that the top of a pipe could be measured after measuring the invert, you just subtract the 2 numbers and have the pipe size. I wouldn't go too wild on my estimate, make sure you build in some wiggle room for your guys. hope this helps.
Doug

Sometimes It Takes 1 Hour To Open The Manhole

Does not take much extra asphalt to lock it in very tight.

Paul in PA

Something to consider

I've never located a mess of manholes (generally for municipalities trying to get the records straight) that we didn't have to go back to 'resolve' some issue.. i.e. "does this one drain over to that one, or does it drain over here?"

Pad it a little for a "clean up" trip.

Two guys measured inverts and located rim elevations with RTK to the same specs. on over 600 manholes in Kittery, Maine in 2006. It all shook out to about 15 minutes per manhole. We walked between manholes and would have to retrieve the truck from time to time. Generally, I would walk ahead of the other guy who was doing the dipping and carrying the "dirty" tools. If I had time to locate the rim before he got there then I did. Sometimes I located the rim after we closed it up and he was gathering the tools. You eventually find a rhythm that works and try to stick to it, and it's definitely a two man job.

Don't forget to carry a long rigid screwdriver or similar tool to scrape the rim after you are done, or the cover may not fit so well when you put it back on and you'll end up twisting many covers just to get it back on - that's a lot of unnecessary work. We also found out that a pair of long crowbars works better than a manhole hook to open the covers. Some covers are clean, but many were filled with asphalt and/or dirt and the hook wouldn't work, but the crowbar worked on every cover.

We did encounter some traffic on Route 1, but for the most part traffic was light. RTK went pretty well - it was fairly open, but time also included checking into BM's and other control as checks. We used the specially made rod with the wheel at the bottom so we could directly read the measurement from invert to rim - that rod was a time saver. Also, I created a spreadsheet that I could take into the field. Ultimately the spreadsheet will have columns for all the specific data you need to collect - this was a timesaver and kept everything in order.

Ed

How Many??? 3 minutes per manhole??

Who do you think you are, TDD?

I've done hundreds of these in Lawton and our SS lines are in the back of lots in the subdivisions. Sometimes access is a huge issue as they are in back yards (fenced, and sometimes with dogs) and lot's of tree cover so RTK can be problematic. And some had sheds or other things covering them.

We have done 50 in a day and we have done 10 in a day. We borrowed a laborer from our sanitary sewer department. Two men to do the lifting of the lids and inverts. And then one man to do the RTK. That way if you have trouble with the RTK then work is still ongoing down the line.

A digital camera is really handy doing the inverts. You can use the flash and then look at the picture and often find all the drops that might come into a structure. Works better than a flashlight and you have documentation as well. (Additional charge if I was in the private). The photo is useful to tag in their GIS system.

The interceptor lines though are usually pretty open but have much larger lines and much greater flows. And sometimes really deep depths. Longer spans on them at times and often cross country with no truck access.

We also made paint marks on the SS manholes as they were dipped. In our town sometimes they would rehab manholes so having the mark told the RTK guy that the inverts were valid.

After having located, dipped, re-dipped and discovered new, literally thousands of MH's. I'd go with the 3-4 per hr average, more on a good day. A lot of it depends on records. Like mentioned above, doing all the invert stuff prior to location sometimes works best.

One of the most important things not mentioned is to connect all the lines to the next structure. That can be a real challenge sometimes, especially in older systems (often combined sanitary/storm) where you have a change in the pipe size somewhere in the line. Banging on covers usually works, but green dye and/or tv'ing may be necessary.

Then if they want diameters, depth to top of cone (for adjusment vs reconstruct), sump depth, other detail notes - all that takes time. But then come time for construction, you won't get those costly extra's while the engineer runs for cover and the contractor smacks his lips.

I do kinda miss all that. Certainly one of the less glorious duties we're stuck with, but kinda cool looking at plans with personal knowledge of all the structures. (assuming the draftsman didn't screw it up)

We use a "dip stick" A lather secured to the end of the level rod a specific measurement.

That way we keep out tools unfouled. Imagine sticking a stinky rod back in your hot truck bed and then opening your silvershield the next day... Woooohoooo