Chiller/mechanical pad on top of existing slope

[geomane]

We are having to add a new chiller/mechanical pad on top of an existing slope at a dam project. I have attached a rough sketch for reference. The pad size and loading conditions are not known at this point; and I know this will influence the foundation type. The existing slope consists of compacted earth fill, clayey sand [SC] with an effective friction angle around 33 degrees. Groundwater will not be an issue. The slope has been stable for 40+ years.

We were originally thinking to just constructing a reinforced earth wall (mse/segmental retaining wall) and ground supporting the slab; however, I think we may have issues with having to shore the soils adjacent to the existing parking and sidewalk area if the reinforcement extends far enough. We will also have to check slope stability for this case.

My second thought is to just install helical piles through the slope and support the mechanical equipment on a platform. I feel this would be quick and easy.

Which of these options do you think would be most cost effective?

 

[oldestguy]

I'd be reluctant to add any load to the slope even if the numbers come out. Water table may change with a lot of wet weather; who knows.

 

[cvg]

good luck getting a permit to drill and install piles in a dam.

 

[PEinc]

Can you drive piles or use drilled shafts to support a platform for the mechanical equipment? If so, maybe you could then attach then attach closure panels around the three sides for aesthetic reasons. Building a pile or pier supported platform would eliminate adding load to the slope and could eliminate the need for sheeting to support the paving when gouging into the slope.

http://www.PeirceEngineering.com

 

[geomane]

cvg, you have a good point

 

[PEinc]

Maybe the piles could be sheet piles. Many dams have sheet piles as their cut-off walls.

http://www.PeirceEngineering.com

 

[oldestguy]

How about H piles?