Documentation for retaining walls

[NH09]

I'm not sure if this post belongs here, but I have a homeowner who is installing an in-ground pool, work started before permit, no plot plan (separate issues). My concern is that the location of pool is on the side of a hill that was built up, a flat area was formed for the pool and the downslope area has a 12' retaining wall holding up the soil. The wall was made of a pre made block (similar to castle wall stone product) and a permit was never pulled for the wall (homeowner pleads ignorance). The in-ground pool is only set back about 6' - 10' from the edge of the wall and the pool is approx. 41' x 24' (significant water weight). What type of documentation should be required to sign off on this wall - an engineers approval?

 

[Alias]

I would require engineered plans for the wall plus the pool installation, especially in the situation you describe.

2007 CBC Section 312 - Utility and Miscellaneous Group U states in Section 312.1 that "Buildings & structures of an accessory character and miscellaneous structures not classified in any specific occupancy shall be constructed, equipped and maintained conform to the requirements of the codecommensurate with the fire and life safety incidental to their occupancy. Group U shall include, but not be limited to, the following: Retaining Walls."

Section 1806 - Retaining Walls Section 1806.1 states that " Retaining walls shall be designed to ensure stability against overturning, sliding, excessive foundation pressure and water uplift. Retaining walls shall be designed for a safety factor of 1.5 against lateral sliding and overturning."

These deal with the requirements in CA in relation to the retaining wall only. Pools are a whole 'nother matter!

Sue, in sunny mountainous CA

 

[fatboy]

I'm with Alias on this one. We would require engineering for the wall anyway, but throw an inground pool in there, you betcha!

 

[rktect 1]

Yup. Yup.

12345

 

[Code Neophyte]

It's going to be difficult to determine how the wall was constructed after the fact - layers of geogrid, width of drainage field, lifts of compaction, # of below-grade base courses, etc., etc., etc. Don't really know how you do that short of deconstructing a segment?

 

[Yankee]

yes, retaining walls over 4' including the footing are a structure (look in the permit section of chapter one and see what is allowed WITHOUT a permit, , ,walls that are NOT over 4' etc etc)

 

[RJJ]

I agree with the above!

 

[cboboggs]

Agree as well.

 

[NH09]

I had also thought of inspections (thanks code neophyte) there is no way to inspect the contruction at the base of the wall, or any other sections for that matter. Plus, to make things more complicated, there is no way to remove a section of wall without impacting the in-ground pool....

 

[pwood]

i agree with what has been said above. i doubt any engineer in their right mind would o.k. the wall without some destructive testing! george r?:mrgreen: where are you? they screwed the pooch on this one.

 

[Mark K]

The pool located on fill should raise a few concerns. A Geotechnical engineer should be involved.

 

[fatboy]

"Plus, to make things more complicated, there is no way to remove a section of wall without impacting the in-ground pool.... "

Stick to your guns, this is not your problem. Force them to present engineering, or remove the whole dang thing. Or, have them take it to your BOA, they will either back you, or take it upon themselves to approve.......don't leave it on your shoulders.

 

[GHRoberts]

i agree with what has been said above. i doubt any engineer in their right mind would o.k. the wall without some destructive testing! george r?:mrgreen: where are you? they screwed the pooch on this one.

Take a 2" soil core. That should answer most questions.

You might also ask for something in writing about the construction of the wall.