validity period for soil investigation report 1

[Balageotech]

Dear Expert,

Very often this question arises in designer community, that whether we can use the soil investigation information which is carried out 10 years before???

Is there any standard guideline that we have to use the past report , apart from practical judgement.

I consider the following points to declared a report as outdated,

(i) If the codes and standards revised after the investigation.
(ii) If the location undergone considerable natural actions such as earthquake , Flood and freeze and thaw
(iii) if the investigation carried out 15 years before

if any one of the above occurred , I will consider the report as outdated.

Please share your views...

Regards
Bala

 

[BigH]

This is how I would look at it. There are two parts to most soils reports.

The first is a factual report. The assumption is that the investigation work was carried out by a reputable firm and that the depths investigated are suitable. This presents the way the investigation was carried out, installation of standpipes, etc., laboratory testing, description of the strata encountered, groundwater level(s), provision of office borehole logs, borehole location plan, sections (used to always be). Unless the site has been mucked about - i.e., dumped fill placed on it, excavations made, significant seismic event (presuming the soils are seismically sensitive) etc., the the factual descriptions and lab testing should not be outdated. You may find that you want some additional information based on your particular project or you wish more "elaborate" investigations (piezocone, DMT, etc.) or that excavations are such that greater depths need to be investigated. But the basic information would be valid - it is a matter of judging if the original investigation was properly done. AND DON'T FORGET TO ADVISE WHATEVER FIRM DID THE ORIGINAL INVESTIGATION THAT YOU ARE USING OR PLAN TO USE THEIR REPORT. This is critical.

The second part of the report would be the interpretive report which would provide the recommendations for design of foundations, earthworks, excavations/fills, etc. This is always open to interpretation. Yes, some guidelines and codes have changed - now the States are getting into the LRFD (a mistake in my view) design rather than the "older" methods. The project may have changed as well - a more stringent settlement criteria or taller structure with greater loads or deep excavations. In this, you should have an experienced geotechnical engineer - preferably from the firm that did the original report - review the information and provide you any additional input or adjustments for your project. Expect to pay for this.

Our company in Canada had a tremendous amount of soils information all over Ontario, Quebec, the East Coast - usually in outlying areas as we were heavily into mining, forestry, pulp & paper, ports and the like. Of course, I used our soils reports from previous years and decades in helping to design a new investigation nearby. Sometimes, it was on the same site.

Whatever the case, you need to use your judgment and exercise prudent caution.

 

[Ron]

Whatever the case, you need to use your judgment and exercise prudent caution.

...excellent advice.

The data from a past geotechnical report can be used for decades, provided appropriate judgment is applied. In most cases for coastal plains soils, only the upper 10 feet or so get affected by land use changes and other construction activities. Provided appropriate methods are used to gather and evaluate data, the subsurface data are relatively unchanged over the years and can be significant for future use....one of the reasons it is necessary to follow consistent, accepted practice.

I was recently contacted by a former partner of mine who asked my permission to use a geotechnical report for an investigation I did in the Bahama Islands in 1988 and 1989. He was referencing the report in a more recent geotechnical investigation done in the same area. I, of course, gave him that permission as I know his reputation and that of his firm. He felt that the data obtained in my report was beneficial to his investigation.

 

[dicksewerrat]

If ground water was present in old report, you may want to resample that for VOC's.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com