HDPE lined ponds - construction standards. 1

[Skillo2015]

I’d appreciate some feedback on the acceptable standards for these ponds. It’s in the Middle East, so temperatures are in the mid 50’s Celsius in summer. I’m expecting expansion. However there is a lot of excess material here. Please advise based on international standards. Thank you.

 

[SlideRuleEra]

Will the liner be covered with soil (40 mil+ thick HDPE), or exposed (100 mil+ thick HDPE)?

Is the question about the liner shown in the photo, or is that just a typical example?

 

[Skillo2015]

There will be sand or soil covering the lining. That is just dune sand that’s blown in to the pond.

 

[Skillo2015]

Ooops…no sand or soil …just HDPE lined ponds.

 

[Skillo2015]

That’s the typical standard of workmanship….I did direct the contractor to pull it tighter as it was being placed…

 

[SlideRuleEra]

Skillo2015 - Work has already progressed on the pond in the photo too far for meaningful advice. The advice I would have given you is to follow the liner manufacturer's installation instructions exactly (no short cuts)... but it is too late for that. For example, anchor trench construction detail is critical. So is panel layout. Same for "slack" allowed at the seams. Ballast is need at the toe of the dikes to resist exposed liner buoyancy. The fact that you directed the contractor to do anything makes it worse... when temperatures drop, the liner "shrinks", stressing the seams. Liner problems/failure are now your responsibility, not the contractor's, not the liner manufacturer's.

So what to do about it?
Contact the liner manufacturer, explain exactly what has been done, and ask for guidance on how to recover from the existing situation. Perhaps putting soil cover (say, 30 cm or more) on what should be an exposed liner will mitigate some problems. Of course, if it works, this will reduce usable pond volume... a trade off you will have to evaluate.

For future work, consider using bentonite geosynthetics like this.

For the above reasons we chose bentonite liners, instead of HDPE, for coal bottom ash pond liners at our electric generating stations on the South Carolina coastal plain (seasonal temperatures 40+C).

 

[dik]

@SRE... Bentonite liners are great...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Skillo2015]

Thank you for the input.

 

[GeoEnvGuy]

American information regarding specifications and white papers linked below. In my opinion 50 Celsius, this should be soil covered. Looking at all the wrinkles there will likely be issues. The big concern I have for lined ponds is what chemicals the operation want to contain and how HDPE or what other material chosen will perform. If I ask the liner expert at the university they tell me they can't say much after a 6 month study with enhanced temperature aging.

https://geosynthetic-institute.org/specs.htm

 

[LittleInch]

These look like Evap ponds to me.

The operators don't really care if they leak, there is a lot of desert out there.

So long as it doesn't leak like a sieve, the tick box for environmental protection is ticked and everyone is happy. Given that the whole purpose is to let the water and other gunk evaporate, there is no way to tell if the thing leaks or not.

The standard of laying of the material in those photos is terrible. The vendors all give good advice on how to lay it but clearly the contractor hasn't read them or just employs people who can't read either. But no one cares. The waste water goes in, the water disappears, who cares where?

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

 

[Skillo2015]

That’s great , thank you very much. It’s for treated waste water, evaporation ponds. Workmanship is not great despite coaching prior to laying.

 

[dik]

Can you not put perforated tiles below to catch any material that leaks... leading to a sump for testing?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[LittleInch]

Dik,

That implies that the operator wants to know.

They don't.

All they want is for the water to disappear. Simply pouring it into the desert is going a bit far and would look bad, so a lined pond is the next best/ cheapest option. Also the lining stops the sand bund from washing away. Then forget about it. That's the reality of life in the desert.

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

 

[dik]

Didn't know that... in Canada, engineers can be held criminally liable for environmental 'screw ups'.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik