Alternative to open trenching or pipe bursting for sewer main replacement?

[handtpipeline]

Ok, here's the deal. We bid on this job I'm doing now, and at first there was about 2,000' of 8" water, and about 1,000 feet of 8" sewer. A while later, we got a call from the general contractor on it, that they needed a price on replacing an 8" clay sewer line with 10" DIP (Ductile Iron Pipe) and rehabing the 8 manholes on it. About 1,100' in all. Need a price within the hour, nothing in the way, and if there is, it'll be taken care of. Depth range from 6' to 12' deep. We were already the winning bid on the 8" work, so we knew we would already be there.

So, we end up getting it, and when we went to see what we had gotten into, find that this "nothing in the way" addition in fact has 225' of asphalt parking lot for a pretty busy restaurant (Delta Cafe), along with crossing both of their driveways (30' to 35' each) plus going right thru the MIDDLE of a VERY EXPENSIVE planter between the driveways. Not to mention about 400' of 300 pair telephone cable that I had to strip out on one section, and move out of the way because the phone company had laid it directly on top of the existing line were are replacing in place.

I've replaced all but approx 500' by bypass pumping, and excavating, just removing the old clay line as we went, installing the DIP. The General is supposed to saw-cut the asphalt, supply ag-base to compact as backfill across the parking lot and drives, and replace the pavement. The planter he said was "no big deal" has turned into a VERY big deal (about $15,000 to remove and re install).

Pipe bursting is NOT an option. Economical alternative to open trenching my a$$... I'm trying to figure out an alternative, that will be less disruptive to the restaurant, and although it would be an extra to my bid price, maybe cheaper than the removal and replacement of all the paving and the planter.

Here is my idea: The clay line has been slip-lined at some point or another, with what appears to be a fiberglass lining. It is smooth and continious inside. I've got road boring equipment, up to and including a 36" casing machine. For each section, I would have to have a 35' long pit, and instead of using casing, build a custom head, with about a 10' long pilot bit, a touch smaller than the inside diameter of the existing line, that would cut about a 13" diameter hole, with 12" augers to bring the spoil out. I say 13", because the outside diameter of the bell on the 10" DIP is 12.91". After reaming a section out, we would then pull the head and augers out, and use the machine to jack the 10"DIP into place.

Am I crazy? Or could this work??? If I could make this work, I could possibly do the entire 225' of asphalt this way, with the exception of 1 manhole in the middle of it that I would have to excavate, then I'd have to excavate about half of one of the driveways to get a long enough pit to go under the planter and other driveway. (the 2 sections are not in line with one another)

I know I'm crazy (I've had enough people tell me that over the years), the question is, am I crazy enough to make this work??? Any input or suggestions will be much appreciated.

PS: Going this route, I own all the equipment needed to do this. It would take me a couple of days probably to rig it up and build the head, but I think I'd save a LOT of time doing it this way. This is the shallow end of this job, ranging from 6' to 8'. The best we did on the other half was 140' in a day, in the wide open, benching the trench out. We were tie-ing in the line every evening, so we wouldn't have to pump all night.

 

[DrJim]

Hello, handtpipeline; First off, you're question is out of my field of expertise--I mostly get along on my good looks. I have been a keen observer of sewer rehabs my entire life--I would slip off from the time I was 5 yrs old and follow the Gradeall wherever it went. And as odd as it may seem, I used to inspect this stuff (for $ 3.25 per hour, if I remember right) back when I was in dental school. So there, I have proved I'm not qualified. But nonetheless. . . .

I realize the contract calls for ductile iron. Your idea is intriguing. creative, and ingenius. But. . . can you push the ductile iron without it undulating up and down some through the bore? I would think that this is where pulling has an advantage over pushing. My engineer bosses would never accept dips and humps in sewer.

How long would you make the undersized "pilot" portion"? I'm thinking that would need to be several feet--5 or 6 ft--to track and guide the cutter.

My biggest question: With pushing, the weight of the pipe will ride on the bells, and the bells will thus plow (dig) the bottom aspect of the bore hole. This is a lot different than pulling smooth continuous (welded) plastic behind a bursting head.

Pipe bursting? Other than the noise, I think it's cool. In my town, it has been used all over as the 67 year old clay sewers are being rehabbed to eliminate (well, reduce) stormwater infiltration. But even with bursting & pulling, they need holes. In the retail areas, in some places they encountered 8-24" of solid concrete under some innocent looking asphalt parking lots, right where they needed a hole. I can't imagine the stress that comes with bidding this stuff on a fixed price.

Keep this thread updated with how your project goes--it sounds interesting. If I could afford a vacation, I'd come work for a week. Good luck--I'm confident that you'll chose the best solution.

 

[heavylift]

I don't know how much pull back power you have with the machine... but a lock joint pipe would pull back thru the bore.. it may keep the bore from collapsing. One never know what under there... a pocket of sand

Just need a swivel and pull plug...

I have done several long bores up to 300 feet...and pulled and pushed... by several different methods...

cables and a dozer winch... that one was a real pain
the easiest was pulling plastic pipe back...

The big jobs I used every auger they owned plus some borrowed stuff. I'm talking 6" to 14" augers... the boss said it wouldn't work with different sizes.. but as long as the first auger is the biggest you need. then you will have a clean hole.. I just put them in a random order..

1. Man hole...set up to bore to the manhole from both directions.. that would make two bore pits and an excavation for the manhole.....

2. Or make the manhole the bore pit... then bore both directions from it... that way you only have one big excavation.. and two small tie end holes...

 

[JBGASH]

There is no reason that will not work, with the exception of hitting rock when boring or other debris items. That practice is routine with many road crossings. I agree, the pipe bursting has its place but I find them far and few between- something always seems to present a problem that was not plannned on, then after you realize that it could have been bored or excavated as quick.

 

[handtpipeline]

My machine is supposed to have about 500,000 pounds thrust. It is a McLaughlin MCL-36. We've done solid limestone bores up to 24" at 300' long with it before. I thought about pulling the pipe after boring, we've pulled up to 500' of 12" steel gas line thru bores on a pretty regular basis at one time. But to do that we welded a pull head on the front of the pipe, and of course all the pipe was welded together. We've pulled with dozer winches, sidebooms, winch trucks tied off to loaded dumptrucks, trackhoes... You name it, we've probably pushed or pulled with it.

 

[CM1995]

I don't have a lot of boring experience (well yes I do but the other kind ) but the first thought that came to my mind was what DrJim said about the bells gouging the bottom of the bore and throwing you off elevation.

What about using casing? Is it cost prohibitive? Do you have to air test the line after installation? Because that would not leave any way to correct a bad gasket/seal or whatever without pushing the entire line through or digging it up.

Just a few thoughts.

 

[Allterra]

I wouldn't be able to do what you're describing in my area due to the fact that they make us wrap the ductile in plastic. How often are they requiring cathodic protection? If your soil is stable enough the pipe should support bell to bell. I wonder the ductile would crack from the pressure being placed on it at the bell?? I think I would get a couple of joints and put them between a loader and something solid and push on them pretty hard to see if they crack. Good luck.

 

[handtpipeline]

My thinking on the bells gouging, as long as I push the pipe spigot end first, the bells make a smooth, gradual transitions to the larger size, so I don't think they'd try to gouge. I was also thinking of pumping some drilling mud in before trying to push the pipe, to slicken things up some. As far as using casing, that would be out of my pocket... So I ain't doing that. If we proceed as planned, the General Contractor is paying for rock to compact back, asphalt and concrete repair, and moving/ re-installing planter. I'm just trying to figure out how to save him some money, save me some time, and keep the restaurant happy all at the same time. There will be no air-test, City will run a camera thru it after all is done.

We have to wrap this with poly-wrap too, so I need to check on that. I don't see how they can wrap it when they do the pipe-bursting thing, so I don't know about that yet. Oddly enough, there is NO cathodic protection on it. The soil so far on this job has been very stable, and I think if I can slick the hole up enough with some drilling mud, it wouldn't take much force to slide the pipe thru.

I came up with this idea, because we've kind of used this method many times when doing pipeline. We would use a water boring machine (usually my 2" Midwestern machine, or a few times even my Vermeer directional machine), punch a pilot, pull back a 6" reamer, then auger the hole out with one of the casing machines, except use a long (5' to 10') pipe pilot welded on the front of the head. It really works good in limestone bores, put a rotary cone head on the 2" machine, and it'll punch thru the limestone at a pretty good pace. That way, when you are cutting the larger hole with the big machine, you can pull your auger string out to re-tooth the head a LOT easier than cutting the casing and re-welding to go back in. We had a lot of trouble with the fold out cutter wings on the rock heads breaking off (designed to fold out when drilling, so they will cut bigger than your casing. Then supposed to fold in when you reverse, allowing making the head smaller than the casing, so you can pull the head and auger string out thru the casing to re- tooth), so the first thing we always did was weld the fold outs on solid. doesn't take but about 1 time of breaking the fold-outs off, and by the time you realize it you've wedged 12.750" casing into an 11" hole... It doesn't pull back out very easy at all...

 

[JBGASH]

I would pull yellowmine pipe back, it will lock together. We have put that in several river crossings and had good luck with it. Your MCL-36 machine should easily handle the job.

 

[Johnstephen124]

Re: Pipe Bursting

I would pull yellowmine pipe back, it will lock together. We have put that in several river crossings and had good luck with it. Your MCL-36 machine should easily handle the job.

I want to share this source for Pipe Bursting I hope its will be very helpful for everyone.

 

[handtpipeline]

Wow. I never updated this thread... We ended up open trenching the longest stretch across the parking lot. We only had to dig up about 5' of the paving along the edge, so it wasn't too bad. I did rig up a pilot and bore all the way across the front, crossing both driveways, some grassy area and under the planter. The bore went perfect, stayed on line and grade (it didn't have much choice with a 6' long piece of pipe welded on the front of the head. I was going to use a 10' piece, but we were cramped for space between a large gas meter setting and manhole for a comeout hole). We had some problems pulling the augers back. We had a pin either fall out or break, leaving part of the auger string about 20' up in the hole from the bore pit... I was going to fish it out, done it before... But the general contractor got impatient and said to go ahead and dig back to it, and he would take care of fixing the driveway. So we dug up about 20' of one driveway. After we got the augers out, I pushed the ductile thru with the trackhoe, no problems at all.

All in all, my method worked well. Would have worked perfect if not for the pin fiasco. It actually was the only part of the whole nightmare of a job that went well. The job was plagued with engineering problems, things in the way that weren't supposed to be there. Just a total nightmare that I still have bad dreams about. And still havn't recovered financially from. I've done a lot bigger jobs, but never one so messed up as this thing was...

 

[JBGASH]

Glad to hear it went good for you. It always amazes me when someone tells me there is no obstacles and then you get on the jobsite and everything possible is right in the way. I have learned my lesson on that a couple times - I make sure I look at it before I reply with any numbers.

Wow. I never updated this thread... We ended up open trenching the longest stretch across the parking lot. We only had to dig up about 5' of the paving along the edge, so it wasn't too bad. I did rig up a pilot and bore all the way across the front, crossing both driveways, some grassy area and under the planter. The bore went perfect, stayed on line and grade (it didn't have much choice with a 6' long piece of pipe welded on the front of the head. I was going to use a 10' piece, but we were cramped for space between a large gas meter setting and manhole for a comeout hole). We had some problems pulling the augers back. We had a pin either fall out or break, leaving part of the auger string about 20' up in the hole from the bore pit... I was going to fish it out, done it before... But the general contractor got impatient and said to go ahead and dig back to it, and he would take care of fixing the driveway. So we dug up about 20' of one driveway. After we got the augers out, I pushed the ductile thru with the trackhoe, no problems at all.

All in all, my method worked well. Would have worked perfect if not for the pin fiasco. It actually was the only part of the whole nightmare of a job that went well. The job was plagued with engineering problems, things in the way that weren't supposed to be there. Just a total nightmare that I still have bad dreams about. And still havn't recovered financially from. I've done a lot bigger jobs, but never one so messed up as this thing was...