water main sewer main conflict 1

[gjeppesen]

I have a project currently under construction that included a gravity sewer extension across 2 adjacent properties to get to the subject property. This gravity sewer main is (will be) located in an appropriate easement adjacent to a road right of way. The right of way did not have room to accomodate the new main which is why we went the easement route.

This construction is on the outside of a curve and a 6" water main is on the same side of the street. Well, unforturnately the water main hugs the right of way line (3" from outside of pipe to R/W line) instead of being 5' inside the R/W like I thought. Because of this the sewer main does not conflict but does not meet State horizontal clearances of 3' from outside pipe to outside pipe.

The problem is the constractor did not pot hole the water main before he started and just installed the gravity main per plan. I have notes on my plan to the effect that the "contractor shall field verify actual locations and depths of existimg utilities prior to excavation". There's also a note "Any discrepancies on the drawings shall be brought to the attention of the engineer before commensing work" Well, he didn't. Now he's pointing fingers at me saying that I designed it wrong.

Any thoughts?

 

[cvg]

did you have a note on the plans requiring contractor to maintain 10 foot separation between the two lines? (hope so)

 

[gjeppesen]

There is a detail that shows required horizontal and vertical clearances.

 

[PELS]

1. Did you have copies of the plans that installed the 6" water main when you designed the sewer?
2. Did you have USA (Underground Service Alert) or the water company mark the horizontal location of the water pipe in the field? (Water mains normally have a locating wire.)
3. Was there a design topography survey that would have revealed valve locations indicating where the water main was?
4. Did you make any attempt to determine the field location of the existing main prior to design, such as discussions with the water purveyor, inspectors or contractor?

These are the type of questions that will be asked of you. Not saying you are at fault but you need to be prepared to defend your design procedure. The sewer should be much deeper than the water main so maybe the agency will allow you to place a concrete cap or some other precautionary measure that will avoid re-construction.

Pipe separation is based on concern for a sewer leak contaminating the water main. If this can be addressed without re-construction and at a minimal cost, then maybe you share the financial burden with the contractor.

Good Luck!

 

[civilperson]

The horizontal separation is not mandatory, only recommended. If less distance is used, casing carrier pipe or mechanical joint ductile iron pipe may be used for the gravity sewer.

 

[gjeppesen]

It's already in the ground.

 

[ptmoss]

How did it come about that the actual location of the water main is now known?

Personally, I have similar notes as you on my plans. Without as-built drawings to go by you're pretty much guessing.

 

[RWF7437]

Did you walk the route prior to completing your plans for the sewer ?

 

[bimr]

Where do you come up with the 3"?

What about the vertical clearance? You may have an option with the vertical clearance, see (B) below.


Reference from a State Regulation:

c) Relation to Water Mains

1) Horizontal and Vertical Separation

A) Whenever possible, a sewer must be at least ten feet horizontally from any existing or proposed water main.

B)Should local conditions exist which would prevent a lateral separation of ten feet, a sewer may be closer than ten feet to a water main provided that the water main invert is at least eighteen inches above the crown of the sewer, and is either in a separate trench or in the same trench on an undisturbed earth shelf located to one side of the sewer.

C) If it is impossible to obtain proper horizontal and vertical separation as described above, both the water main and sewer must be constructed with water main quality pipe and joints that comply with 35 Ill. Adm. Code 653.119 and shall be pressure tested in accordance with "AWWA Standard for Installation of Ductile-Iron Water Mains and their Appurtenances," ANSI/AWWA C600-93 (1994) (no later editions or amendments) for a working pressure equal to or greater than the maximum possible surcharge head to assure watertightness before backfilling.


I agree that you should have a reference in your specifications to:

"Standard Specifications for water & sewer main construciton in XXXX(state)"

 

[cvg]

so, you would dig up the sewer line and re-install with ductile iron pipe and mech joints? or dig it up and encase the entire thing? You would also apparently need to dig up the waterline and restrain it also. Lets hope it is at least below the watermain.

 

[coloeng]

Did your drawings specifically direct the contractor to verify the location of the water line in this particular area, or is your note just a cya. If it is just a cya, did you really expect the contractor to expose the entire water line to make sure there was at least 10'separation between them for the entire length of parallel lines.

It is my opinion that the Owner, or his engineer, should take the risk in a situation like this, unless the contractor new that there was a problem and failed to notify the owner/engineer. If the contractor didn't know that the water line encroached closer to the right-of-way line than the plans showed, how is he supposed to know that he should pothole it at that location, unless directed to do so.

If you get in the habit of making the contractor assume all of the risk, you will end up paying more for all future projects because the contractors will have to increase their bids to cover any risk to them. If the Owner assumes the risks, the contractors will know that they won't have to add cost for those potential risks. This will save money for the owner in the long run.

I'm not saying that the owner should allow the contractor to not construct a project to the specifications, but you have to realize that a contractor is out to make money and if there is the potential for risk on his part, he will add money to his bid to cover that risk.

I know this from 15 years experience as an Owner where we have consistently had projects bid at 20-30% lower costs than an adjacent city primarily because we assume the risk for unknown conditions and the city makes the contractors assume the risk. These lower costs have ended up saving us around $7.5 million in those 15 years. How much engineering can that pay for?

 

[gjeppesen]

If a note is on the plans, it is part of the contract. Isn't every note really a cya? I ran this by 2 contractors that I work with regularly and they said that they would've potholed the water main 1st, no question. They do it on every job on utilities that are somewhat close before they even get on a machine.

Of course this contractor is the cheapest, and there's probably a reason why.

By the way I only need 3' of horizontal clearance, not 10'.

 

[ptmoss]

gjeppesen, why is there finger pointing now? I don't understand why this came up now during construction unless someone with knowledge of actual location stopped by and pointed out where the water main is.

 

[bimr]

All Contractors make these kind of statements, especially when it points the finger at someone else:

"I ran this by 2 contractors that I work with regularly and they said that they would've potholed the water main 1st, no question. They do it on every job on utilities that are somewhat close before they even get on a machine."

 

[gjeppesen]

No one knew it was that close until the contractor started digging. The water main is in the same trench as the gravity sewer. Instead of stopping when he discovered there was a problem, he just kept going and didn't call me.

 

[gjeppesen]

bimr,

No not all contractors will do as you say. I hce long standing relationships with these folks and they'd give me straight answers. The contractors you speak of are the ones I stay away from. Sounds like you don't trust the contractors you work with with giving you straight answers.

 

[bimr]

It is nothing to do with being a Contractor, it is human nature to make statements like that. I have had a number of "good" Contractors make the same statement.

Anyway, my understanding is that the utility locating service is responsible for locating utilities, not the Contractor.

Contractors everywhere are required by law to locate underground utilities before digging. Was this done?

If the utility locate was done, it should have picked up the water main since it is so close.

http://www.illinois1call.com/pdf/excavator_handbook/ExcavatorHandbook07.pdf

 

[eea]

Agree with bimr here. Nearly (if not) all 50 States have "one-call" locating services requirements. Sounds like gjeppesen has this covered by general note. Even if not, it’s probably state law for the party doing the work to contact the utility. That would be the Contractor. One would have also hoped for a design locate; I assume that's where gjeppesen got the design offset distances.

For the Contractor to install a sewer in violation of the state's minimum WM separation guideline is a finable offence (here in Illinois) to both the Owner & Contractor and possibly the Engineer (if the plans are silent or if you ignore the current problem). You should check your state's requirements, but the Contractor's position is pretty weak at best.

Now assume that he had actually potholed first and notified you and Owner, what then? You probably would have reolcated the sewer or considered encasing the WM. The resolution then would have not been free either and would have been on the Owner's dime. There is some middle ground to find.

Keep us posted.

 

[cr1973]

I hate to go against a fellow engineer, but you cannot expect the contractor to pothole and expose utilities that run adjacent/parallel to the proposed construction.

Sure, the contractor should pot hole ahead wherever the proposed construction CROSSES a known utility and needs to account for grade, but I don't think you can expect them to pothole along the entire run of the project - outside of their future trench - on adjacent utilities.

Depending on depth of the sewer, might just be easier to offset the water main if you can find out how much of it needs to be moved.

 

[gjeppesen]

Yes, locates were called. Problem is the existing water main did not have locating tape. So the water company flagged it where they "thought" it was. They potholed in one spot, but that was it. The flags were about 3' off of the actual location of the water main.

cr1973, I think it could go either way. The good contractors around here would pothole, and the bad one's don't. Problem is you pay more for good. Not saying it's that way everywhere, but it is in this town.

The thing that gets me is the contractor wasn't meeting his minimum 3' horizontal clearance about 40' into the install. Then he continued to lay another 100' even though it was wrong. He failed to call the GC he was working for or me the P.E. Now we have to pay to rip it all out and re-align it.