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Question DetailsAsked on 11/28/2014

what are common methods to replace a water line

Is a sleeve recommended with hdpe water line?

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5 Answers

0
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Almost always dig it up and replace it - though if you have a lot of stuff built overhead in-place pipe bursting or boring and thenn pulling in a new pipe can be used, but typically costs about twice as much as open trenching - not counting any costs of repairing disturbed surface.


Unless you have an oversized line - like 3-4 inch, lining it is probably not a good idea, because normal residential water line is only 1-2 inch so lining it typically reduces the diameter enough that it reduces your flow to showers and such too.


Pull-in sleeving rarely is used in small (less than 3" lines) because of installation friction and because it dramatically reduces the inside diameter, though it is possible to use inflated epoxy or resin-impregnated sleeving - though again an expensive solution.


Perhaps if you used the Answer This Question button right below your question to reply back with more details on why you are considering sleeving (or needing replacement at all), it would clarify matters. Especially since you say you have HDPE line - unless this was early HDPE, built in the early 80's or so before they got the mix right for long life, it would not normally be expected to have gone bad in general in this time frame, so normally just a spot repair at a damaged place would be the type of service expected.

Answered 5 years ago by LCD

0
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Thank you LCD. Current 200" long 50 year old pipe is les than 200psi poly. 3 leaks replaced with 200psi. Recommendations include trenchless or mole beside the existing pipe (under 2 asphalt driveways) with sleeve to prevent the rocky soil (lots of small rocks and a few 4") from tearing the HDPE pipe, or trenchless pulled without a sleeve, (which the city itself uses). Your thoughts? How does a sleeve (wider diameter poly) reduce diameter of my 1" pipe? (No bursting due to brass fittings from 3 leaks).


Also conflicting remedies for connecting the pipe to the main inside the house. The connecting point to the main, vertical copper pipe in the garage (galvanized where it heads under the concrete) is 2' to the side of the garage door and 1' over from the edge of the driveway/concrete pad, opposite a concrete retaining wall 4' higher than the driveway (at the entry door) , filled with a large rhodie. The outide pipe runs beside a wood retaining wall under the gravel driveway- sight of a leak). The assumption is that it then heads straight for the inside pipe, meeting it at the rhodie. 1) Run the pipe under the concrete pad beside the retaining wall and make a hole inside and outside the garage to angle connections 90 degrees to reach the inside main. 2) Make a straight line to the point of connection (ending with 10' copper pipe) and trash the rhodie, to avoid these 90 degree connections. (Sounds like the 10' copper pipe extension is a legal requirement).

Answered 5 years ago by Guest_9781667

0
Votes

Presume you meant 200' long,not 200" - which might weight in favor of trenchless installation if in a deep burial zone.


OK - you had said HDPE, now poly - is this HDPE (which is tough as anything, assuming rigid rather than flex tubing), HDPE seamless flex tubing, or PE tubing (polyethylene, like drink bottles are made of) or more likely if rigid pipe, PVC ?


Personally, when you say under 2 driveways I assume you mean crossways to, not along the length) - not a big thing to patch driveway anyway unless you are a fanatic about appearance (because patch over a ditch will show)- but the cost of patching a driveway versus higher cost of trenchless installation - no comparison in most cases unless trenchless pipe installation is unusually cheap in your area. Plus, for 200' run in rocky soil, they would likely have to open up a drilling site halfway along to do a trenchless install anyway - the machines that can do 200' continuous runs are pretty expensive to operate. So, unless a lot cheaper - which probably means deep curial due to deep frost conditions, I would say trenched would be your safest bet - especially if your area has the occasional large rock. One major problem with trenchless is it tends to worm out voids under rocks that are large enough to stay in place rather than fall into the hole like sand and small gravel, so after you put the pipe in place the earth pressure, which tends to gradually close the hole up, can press a large rock into the pipe and puncture it. Of course, a lot more of a concern in shallow bedrock and mountain/canyon/steep creek areas where the rocks are sharp than in larger river valleys where they have been rounded.


If you have punctures in the pipe now, doing a trenchless install (unless heavy wall, expensive field-seamed rigid HDPE lengths) is likely to cause the same thing again in the future - I would generally prefer to trench and uses proper coarse sand or pea gravel backfill around the pipe (typically 4-6 inches all around) if all that you are damaging by doing so is asphalt driveway.


When you said sleeve, I assumed you meant sleeving your existing pipe - internally. Sounds like you mean a pulling sleeve - an outer plastic pipe, which the actual water pipe then goes inside. Certainly that would protect the water pipe somewhat from rock punctures, at least from small ones, certainly if it is a semi-rigid pipe rather than flexible, "soft" tubing.


I guess if you are comfortable with a pulling sleeve, then internal to that the actual waterline, I would give the contractor both options - that and trenched, at their discretion. Be sure to specify that backfilling where it crosses the drives has to be well compacted to driveway construction standards, with proper base material and asphalt paving to match current construction, all as part of their bid price. Ditto to repairing any damage to sidewalk - and replacement should include connection cost to city line. You will have to decide whether to require that be a new connection tap to the city main (costly at times), or if you will accept them connecting onto the existing tap - which may mean leaving a few feet of the old pipe connected to the main, depending on kind of tap - usually tap is at main (in street usually), with a tap line to the property line or sidewalk, where the shutoff valve box is - your connection point is usually at the shutoff valve.


Also - if sleeved, but sure the open end at the house is well sealed, so if you get a leak somewhere along the way you do not have an open passageway inside the sleeving to your garage. Usually use an expanding waterproof polymer foam for that,, several feet into the sleeve, though there are mechanical packings make for that too.



Connection to house - tunnelling under the house can have bad consequences - cracking foundation, settling slab, etc years later because the drilling removed material from under the house. I prefer to always come in alongside the house if possible, then a 90 and run the shortest distance possible under slab and foundation into house, then up into the ceiling joists to the old distribution point. And remember - if boring the line, they cannot hit an exact target unless usingthe old line as guidance, with a pilot probe on the bit (which not all can do) - within a few feet is considered normal, so coming up to a "clean" point on the foundation away fromthe front door and rhodie might be your best bet - maybe even other side of driveway on the garage ace (sounds like side away from the house), then an emergency shutoff valve (indoor if in freezing country) and new inside line (which could still be the larger service diameter rather than the probably 3/4" interior pipe size) inside the garage to tie into the existing piping.

Remember the connection between the outside line and the inside is a likely leak location so consider where that connection is made - maybe outside the garage rather than inside. That is the reason some jurisdictions requirecopper for the last x feet of run, plus it is generally more forgiving of foundation movements.

Remember also that copper and concrete do not mix - it needs to be sleeved through the concrete to avoid any close contact.


Answered 5 years ago by LCD

0
Votes

Such generosity LCD. Thanks so much for the education. Hours of googling followed.

A bit of follow-up as I choose a contractor, if u have a moment.

I have a water heater expansion tank. No problem then, with pressure in the house once PRV is installed at the meter or at my indoor shut off valve?

Mole and directional drilling - different limitations? Mole is suggested

What is a "clean point" in the foundation?

HDPE 1" 200 -220 PSI is rigid or flexible? I will find out what contrctors are using. Sounds like PEX is ideal with qualified installers, but $$.

Few of the stats I've read highlight puncture resistance. I see your point about rocks in trenchless. Hmmm, How to decide......

Answered 5 years ago by Guest_9781667

0
Votes

The water heater expansion tank provides a place (by compressing the readily compressible air pocket in the tank) for hot water expansion as the water heater heats up to full temp - otherwise, if you have a backflow preventer (many older houses do not have, but generally required by code for new work) that hot water expansion can cause damage. Generally it will not hurt a full-size house system with good pipes because there is a lot of pipe footage to take up the slight expansion, but in small houses/condos with individual backflow preventers and as pipes and water heater get older can then cause premature failure of a weak place that might not have otherwise failed for many years - or ever. Therefore, most areas require an expansion tank somewhere between the water heater and any backflow-preventing device - either a backflow preventer or a pressure regulating valve - and it has to be on the "house side" of both those two devices to work right.

Mole and directional drilling - directional drilling is horizontal drilling with a special drill rig but does require open trenching at the connection point at both ends, so does not entirely eliminate the backhoe, and with the equipment normally used for residential service, is accurate within a few feet horizontally.. This is why they want a "clean point" on the foundation - a place preferably at least 6 feet wide where there are no support piers into the ground, and no utilities nearby - sewer, power, phone, etc. A mole is a miniature tunnel boring machine - rarely used for residential jobs due to higher cost as a rule, but are being used in a few areas now especially in self-support clayey soils, and for longer runs. If they use laser control can be accurate within inches, or if run by eye can be off many feet.

In your case, use of one of those might be economic if you are passing under a lot of things that are expensive to disturb or your burial depth has to be quite deep due to frost depth, but normally trenching is cheaper. Even in my area, with typically 8-10 foot burial depth and with directional drilling the generally used method for underground utility lines, trenching is the only method used unless trenching can't be done because of interfering buildings or substation or such - trenching (even with sidewalk or driveway repair) is just generally so much cheaper.

HDPE 1" 200 -220 PSI is rigid or flexible? Can be either - coil tubing can eliminate possible weak points at the joints (though typically comes in 40-50' coils, so unless a 200' coil is ordered specially you will still have some joints), but is much thinner than rigid pipe (so it can be coiled) so more prone to punctures from rocks. For example, just pulled randomly off one supplier's sheet, their 200-250 psi rated flex tubing has a wall thickness of 0.113-0.120" depending on thjickness. Schedule 40 HDPE (rigid stick) has a wall thickness of 0.133" and pressure rating of 450 psi, schedule 80 0.188" wall and 630 psi rating.

PEX is ideal with qualified installers, but $$. - I think you were reading interior piping there. PEX is not allowed for buried lines in most areas - too puncture prone. PEX is a cross-linked polyethylene - similar in chemistry to soda bottle material and the material used for polyester fiber, recycle code #1 on the bottom. HDPE is High Density Polyethylene, which is far tougher and stronger, recycle code #2 - the material commonly used for rough service mine slurry pipelines and landfill liners, and for the near-unbreakable reusable black drink bottles, many of the black interior car panels, and some heavier-duty bottles like laundry detergent.

Trenchless has a couple of inherent issues - if not done accurately, it can be a risk in deep frost areas if the bore snakes up and down so it comes too shallow in the run. We have discussed the puncture risk from sharp rocks - not only in country with natural sharp rocks like talus slopes or shallow bedrock, but also in other bouldery to gravel country because the drilling creates sharp edges as it drills through and breaks up the native material. In our area for instance (with generally rounded material of all sizes), the electric and telephone utilities are spending a LOT of money replacing direct burial cables that were either trenched and backfilled without sandy bedding material to got punctures, or were put in with directional drilling and have punctured over the years (letting water into the cables), so they are going back with directional drilling and installing very heavily metal armored cable with a very heavy plastic outer protective sleeve layer - in may cases using an outer plastic sleeve pipe as well. Personally, I do not like directional drilling with coil pipe because of this risk. The heavier-duty Schedule 80 PVC or HDPE 20' lengths of rigid pipe is my preference for installation in bored installations. However, I think you mentioned the possibility of them sleeving the bore (or was that another question) - if a rigid protective sleeve is pulled through, then as long as the soil is stable (not a talus slope or susceptible to movement) then the flex tubing inside that should be fine.

I would decide if bored installation is suitable to you, and if so if you want to require a heavier pipe or an outer sleeve if done that way, but I would NOT say you want a certain method - I would specify installation methods acceptable to you, protective sleeving if desired for bored installations (and proper sand/pea gravel bedding if trenched) and let the bidders decide which they want to do. I know I have put jobs out to bid allowing either (for commercial work, long runs) and sometimes boring, sometimes trenching with a backhoe came in cheapest. And in some cases it was surprising - I have had contractors with low overhead and equipment they own come in with fairly small backhoes to do long runs, and others with a vastly oversized backhoe that happened to be idle come in for smaller jobs. have even had companies with large electrical cable rock trenchers come in on buried water line jobs because they were not booked for that day, so let the bidders decide HOW they want to do it (within your limits of acceptability) to give you their cheapest price.

One other thought - if you have foundation french drains, be sure to note that in the bidding and ensure their method does not disturb them, and also that they do not leave a permeable path under the foundation for water to come from that drain to your basement slab or underdrain system - require an impervious cutoff be installed where they go under your foundation. And prohibit drilling through your strip footer. A Hole through the foundation walll should not be a problem (in shallow frost areas), but generally they should go under the footer then up inside the house except in frost-free areas - in which case trenching would almost certainly be cheapest anyway.

Answered 5 years ago by LCD




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