Aquatic Technology Pool & Spa, "Creating Water as Art."™

Aquatic Technology Pool & Spa, "Creating Water as Art."™
Pools as an art form - the way it should be!

Tuesday, April 1, 2008

Structural Engineering & Geotechnical Reports

Now here's the dilemma... a volume pool builder provides a bid based upon a structure of MINIMUM specifications. They usually have not reviewed any geo-technical reports (aka: soils report) to ascertain just how strong the structure needs to be.

Pools are designed (usually) to hold the "forces of the earth out" & not the "weight of the water in." THERE IS ABSOLUTELY NO WAY to determine the engineering requirements of the structure without defining the soil conditions on a site.

But most swimming pools are built with generic engineering, purchased in volume from a production mill engineering firm. These plans are valid, ONLY if the engineering used from the plan meets or exceeds the soil conditions of the site. It is the structural engineer's responsibility to review the soils report to determine what plans are required. IT IS NOT the pool contractor or salesman's job to define the strength of the structure. You're lucky if the contractor is a college graduate. And I doubt that they will possess an engineering degree or have an on-staff structural engineer (though there are a few out there!).

"Standard library engineering" is a cost effective & acceptable means of designing structures. However, the use of these type of plans is only valid if their selection and use is based upon the structural engineer's review of the soil & site conditions.

Some municipal planning & building departments are starting to become educated. Many are now requiring a geo-technical review of a proposed site. They are also requiring that the geo-technical engineer review the structural engineering to determine it's adequacy. Often times an inspection of the open excavation is performed to verify that the soil conditions are no worse than anticipated by the preliminary geo-technical investigation. Some municipalities may only require a geo-technical report in predefined "geo-hazard zones."

Bear in mind that the soils report is usually based upon a boring or test trench. The report is based upon this small sample of space upon the property. Oftentimes the test trench or boring will just barely miss (and therefore fail to identify in advance) an obstruction, large rock, incompetent pocket of material, or other deficiency. Yes, sometimes a project has to be halted while the experts (geo-technical & structural engineer) regroup to redesign the engineering.

The builder & geo-technical engineer CAN NOT be held responsible for these unforeseen obstacles. After all, it is the property owner's land... If buried treasure was unearthed, the property owner would surely be out in the yard laying claim to the bounty. So why are they not also the owners of any negative finds?

The foundation for a building has to be designed to meet the soil and site conditions. So why shouldn't a pool, which is built ENTIRELY in the ground, meet those same requirements?? Alas, IT IS! It is in the building codes (Uniform & California) that structures be engineered for the site & soil conditions..... and a pool is a structure!

When the pool cracks, goes out of level, sinks, or slides down the hillside, this generic boilerplate engineering will be invalid, if it was not selected by a structural engineer with the site and soil conditions as the determining factors.

In California, geo-technical investigations begin at around $5,000. When volume pool builders are competing on who has the lowest price, the requirement for the property owner providing a geo-technical report can "over price" their bid. Therefore, few will ever ask if a soils report is even available.

That should be the first criteria when selecting a builder - Does he take the initiative to inquire if a soils report is even available? If there is one available is he going to provide it to the structural engineer to review? Will the structural engineer issue documentation (plan notes, invoice, letter) that he has ACTUALLY reviewed the soils report?

Paolo Benedetti - Aquatic Artist
"Creating water as art."™

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