Suction pipe through levee --- Schedule 40/80 PVC vs. C-900 vs. Ductile Iron vs. Smooth Steel

[lakebuilder]

I am planning to build a 47 acre reservoir/lake on my row crop farm in Mississippi in order to collect runoff rain water and store it for irrigation use. The earthen levee/dam that will be constructed will be approximately 26 feet high at its tallest point and approximately 240 feet wide at its base. I am trying to determine what type of pipe material would be best suited for the 16" wide suction pipe needed, as this pipe will need to run through the levee/dam's core structure near its base at the bottom of the lake to the pumping station on the other side of the levee. This 16" wide pipe will be approximately 240 feet in length and will be buried under 20 feet of the dirt levee. I am concerned about the pipe potentially cracking, breaking loose at joints, corroding, deteriorating, leaking, etc.

What type of large diameter (16") pipe material would hold together best in this environment and not likely leak under the settling weight of 20 feet of levee sitting on top of it?

Should I avoid ductile iron and/or smooth steel because of their possibility (or maybe likelihood) to corrode (particularly from the exterior)?

Should I avoid PVC due the possibility of the large glued joints breaking loose and leaking due to the foreseeable shifting and settling of the 20 feet of dirt above?

Would gasketed C-900 be a better idea since it is strong and won't corrode and can also be used with thrust restraint harnesses instead of large, glued joints?

Your thoughts and advice will be very much appreciated.

 

[bimr]

A soil loading of 20 feet is something that should be addressed but should not be a significant concern on buried pipe.

One would think that you should have the expertise of a qualified professional to design and build the dam and that person should assist you with the pipe recommendation.

 

[lakebuilder]

Thank you very much for your reply. I failed to mention above that I have already consulted with a professional engineer, a pipe sales rep, a pipe installer, and also multiple earth movers who build dams and levees in the area. While I have been presented with the aforementioned various types of pipe as potential options for me to choose from, I have yet to receive a single recommendation for which type of pipe should be used under the circumstances presented above. All that I've been told are some Pro's and Con's of each type of pipe...but no recommendations as to what type would be best. Apparently, no one with whom I've consulted seems to really know for sure what specifically to recommend....which is why I'm now here on this forum reaching out to see if anybody here might be able to provide me with some much needed guidance based on their experience. Thank you again.

 

[LittleInch]

Personally I would be looking at a thick PE pipe. This won't corrode and is very forgiving of settlement or ground movement.

The steel pipes can corrode and DI and PVC can crack. Anything with a mechanical joint can leak.

If you're worried about collapse perhaps insert the PE pipe inside a sleeve. A 16 inch pipe doesn't sound very big for such a large body of water though.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[lakebuilder]

Thank you, LittleInch. You are the first to ever mention to me the possibility of using PE pipe here, and it sounds like a very interesting product. I'm not personally familiar with it, but I will definitely be looking into that now. Thanks again for the helpful suggestion.

 

[cvg]

first of all, a 47 acre lake, sounds like you might be impounding a large reservoir. all US states except Alabama have dam safety regulations and you will be required to get a permit to construct a dam from them. they will review and approve your design.

https://damsafety.org/states

The size cutoff for jurisdictional dams is generally 25 feet high and 50 acre-feet of storage and it sounds like you will exceed both of these.

https://goo.gl/images/wZ7aGq

suggest you start by reading those regulations from your state to see what requirements they have for pipe penetrations.

The following types of pipe are commonly used for low dams. they have gasketed joints and can withstand a significant amount of pressure:
• Reinforced Concrete Pressure Pipe, Steel Cylinder Type, AWWA C300
• Concrete Pressure Pipe, Bar-Wrapped, Steel Cylinder Type, AWWA C303

Local state regulations would not allow either PVC or PE and glued joints would absolutely not be allowed. Encasement with concrete and surrounded by a filter diaphram would probably be required.

https://www.fema.gov/media-library-data/20130726-1515-20490-8766/fema484.pdf

 

[bimr]

Agree with cvg recommendations's. PE pipe will not be acceptable.

 

[lakebuilder]

Thank you, cvg and bimr. I have recently completed the permitting process with the state and have received the three permits required from them for this reservoir project. I have also received an agricultural exemption from the permitting process from the US Army Corps of Engineers, so I am told that I now officially have been given the green light to proceed with construction. The state approved design of this planned reservoir does not appear to specify which type of suction pipe material will be used, so I can only assume that it was not required by the state to specify such on the design.

The engineer, who has assisted me with the planning and drawing of the design, does not seem to have a strong opinion one way or the other as to what type of suction pipe material should be used and has indicated that PVC with glued joints is very commonly used on projects like mine in the same county and that glued PVC would likely be fine for my project. The local pipe sales rep has also confirmed that he most commonly sees glued Schedule 40 PVC but also welded smooth steel pipe being used as buried (through the levee/dam) suction pipe in these irrigation reservoir projects. However, based upon my own research, it appears that the general consensus on this forum is that PVC with glued joints is highly discouraged.

You can imagine that I'm pretty concerned by the vastly different information that I've either read or been told, and I'm clearly not confident in making a choice of pipe material at this time. Any other recommendations or guidance that you all may have would be very greatly appreciated.

 

[bimr]

PVC with glued joints is considered to be a restrained pipe joint system.

Those with more experience in buried piping systems recommend unrestrained joints for buried piping because the earth will move and the unrestrained joints will adjust and not break.

 

[lakebuilder]

Thanks very much, bimr. That's the type of information which I am seeking.

So, which types of pipe material would allow for unrestrained joints?

 

[bimr]

For example, a bell and spigot is an unrestrained type of joint.

As cvg recommended, Concrete Pressure Pipe, Bar-Wrapped, Steel Cylinder Type, AWWA C303 is a good recommendation. Gasketed joints.

http://www.thompsonpipegroup.com/wp...te/style/images/Steel/WHITE-Product-sheet.pdf

 

[lakebuilder]

Thanks very much. I will definitely be looking into this type of pipe. It looks to be very toughly designed. I just hope that it'll fit into this farmer's budget. Thanks again for your helpful suggestions.

 

[LittleInch]

That Fema document seems to have a number of HDPE slip lined examples where the PE was inserted into old concrete or steel lines. It's a big document so couldn't see where it said they were not permitted or recommended.

I'm not questioning the comment that they are not acceptable, but just curious as to why not.

To me if you want the best of both worlds then use a concrete pipe to take the load / settlement etc then insert and grout in a PE liner for long term no leakage of the pipe.

I still think 16" is very small for such a large body of water.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[cvg]

LI - FEMA does not review, approve or permit dams so even though they publish a manual, it only contains general guidelines for design. They do accredit levees in the national flood insurance program, but again those levees need to be certified by an engineer and permits issued by the local agencies. Sliplining to reduce leakage on pipes may be a good idea for long term maintenance, however it is not generally done for new construction.

Agree that 16 inch sounds far too small for this application. I question why such a large reservoir with such a small water delivery system. I would hope there is a principal spillway which can handle the 100-year flood discharge which would probably be much larger than 16 inch diameter.

 

[lakebuilder]

The concrete spillway structure will be 6 inches thick of 3500 PSI concrete reinforced with rebar and will be 47 feet long by 16 feet wide across the flat top of the levee and then another 14 feet wide (by 47 feet long) along the sloping exterior side of the levee followed by a large area of rip rap and a ditch.

As far as the 16 inch suction pipe through the base of the dam, I've been told by the irrigation system designer that the 16 inch suction pipe will provide sufficient water and pressure to the pump which will in turn send a sufficient amount of water with enough pressure to the main center pivot via a smaller 12 inch pipe.

Assuming it would be at full capacity, the reservoir's 411 acre feet of water will allow me to irrigate 493 acres of crops with 10 inches of water during the very hot central Mississippi summer.

My only real concern that I have here is in regard to the type of suction pipe to use that will run through the base of the dam and be sitting under 23 to 25 feet of dirt. After doing some research of my own and also reading your comments, I'm now scared to death of using PVC and glued joints, which is what had been previously presented to me as a good option. I will now be looking into the AWWA C303 pipe for sure.

 

[lakebuilder]

Do you guys have any thoughts on using asphalt coated (to resist corrosion), schedule 40 smooth steel pipe in my scenario? This new option was just presented to me today by the irrigation pipe sales rep. He is unfamiliar with C303 pipe.

 

[bimr]

Asphalt lining is a really old coating system and may add an estimated 10 years to the anticipated piping life. The estimated life of this type of pipe may vary from 20 to 30 years depending on the corrosivity of the soil conditions which are variable depending on location.

 

[cvg]

agree, asphalt coating is about the cheapest option. coal tar would be a step up. cement mortar lined and coated, wrapped exterior with coated interior or epoxy lining would be improvements. joint design is also important to consider

http://www.nwpipe.com/wp-content/up...Control-Linings-and-Coatings-NWP-Brochure.pdf

 

[lakebuilder]

Good to know, bimr & cvg. That's very helpful information. Thank you both.

 

[amlinerrichard]

Have you looked at HDPE with fused joints?