Swimming Pool Construction Design Napa Sonoma California

Are soils reports required by the Napa County Building Department for swimming pool construction permits?

Napa County Memorandum 2013.10.4

The Napa County Memorandum dated October 4, 2013, entitled "When a Geotechnical Report is Required," is ambiguious.  In fact it does the citizens of Napa County a disservice.

Quoted below is an excerpt of the memo:

"WHERE REQUIRED
A soils investigation shall be required for all new and replacement structures as well as additions and changes of occupancy within the unicorporated portions of Napa County with the following exceptions:
Exceptions:
...4. Swimming pools which are designed with the assumption of expansive soil."

Expansive Soils - Come in all shapes and sizes

"Expansive soils" is not very descriptive.  The expansive index for soils is vast and wide.  

Had the above memorandum stated, "soils below 45 PCF," then that would have meant something.  It would have placed a quantitative value on the soils that they would not require a report.  But, how would you know that value, without a geotechnical report? (back to the chicken v egg quandry).

Simply designing a structure for "mildly expansive soils" (45 PCF) will not be sufficient if a site has "highly expansive soils (120 PCF)."

The question is, "How expansive is expansive?"  The truth is, only a geotechnical report will tell you.

Sloping Properties

If the proposed swimming pool is near a slope, then a geotechnical report is required by the State Building Code.  

The setbacks and slope stability requirements need to be defined.

So, just because a County Official says it ain't so, does not mean that it "aint so."  

Besides, you cannot tell the players (expansive index) without a scorecard (geotechnical report).

Contact the author, Paolo Benedetti of Aquatic Technology Pool and Spa at: info@aquatictechnology.com or 408-776-8220. 
Visit his website at: www.aquatictechnology.com. 
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