GEO-TECH study?

[shadmani]

Sorry for a dumb question, but I am working with a group of people on the development of a power plant located near a lagoon. We need to conduct a geo-tech study, and I need to understand the basics as to what all is involved in a geo-tech study (high level snapshot of activities). Any help appreciated

 

[GeoPaveTraffic]

The high level veiw of a geotechnical investigation, i.e. geotech study, is generally as follows:

1. Client and geotechnical engineer discuss the project.

2. Engineer provides a proposal with a plan of investigation. Client approves or the plan is revised until it is approved.

3. Engineer does a review of avialable informaiton, this should be started as part of the proposal preparation.

4. Field investigations are performed. This will likely be borings, but could include test pits, feild recon., cone penetrometer tests, and others.

5. Laboratory testing is performed.

6. Data is analyized and specific recommendations developed for the site and the proposed construction.

7. Report is issued.

There could be verious meetings and steps 4, 5 and 6 can be repeated based on the data collected, the complexity of the proposed construction, and the site conditions.

Time frames can be as little as a month for the whole process or as much as several years. You indicate that the investigation would be for a power plant, I would expect a couple month effort at least. If there are exist improvements in the area, there is likely a geotechnical report for those improvements around somewhere. I would suggest that you find it, look it over, then contact the company that did that original work as a starting place.

 

[eric1037]

Resistivity testing is usually performed during the geotechnical evaluations for power plants and substations as well.

For the two power plants that I have been involved in, the geotechnical investigation was very thorough and detailed. I would recommend a qualifications based selection, rather than competitive bidding. (I recommend this for any project, actually.)

A geotech firm should have prior experience with power plants.

 

[shadmani]

thanks for the response guyz, basically the team has selected a certain site after doing power evacuation studies (stuff that ensures power good be delivered on the electrical grid) and now we need to see if the land that is being recommended is OK for a power plant. That is how we landed to the geotech topic. I think the resistivity point is a very good one. Unfortunately, we would have to go with competitive bidding due to the local laws, however, the route I was trying to take was to do an initial snapshot type study first to see if the site is even worth pursuing, and based on the initial results take the path forward and do a full fledge study.

I guess a follow up question would be if we can do an initial fact finding study, and based on the results, do a final detailed study. Any cost estimates? The site is about 60 hecters and we were thinking about initially doing like 6 soil samples (I think you call it core boring?)

thanks again for replying

 

[GeoPaveTraffic]

Do not, I repeate, DO NOT, get bids from engineers for this type of project. Look deeper into the local laws, I suspect that they allow engineering services to be selected based on qualifications.

The outline I gave above can be used to do an initial site review. This may only ential a short review of existing information and a site visit by the engineer. This would be followed by a report discussing the site, potiential problems, etc. and a recommendation for the next phase.

Without much much much more information, no one could even begin to give a cost range.

 

[BigH]

I agree with GeoPaveTraffic that you don't go out for bids for the geotechnical on this - unless you have, through proper research, narrowed it down to two reputable and very experienced firms. Such investigations require more than what firms dealing daily with housing developments, commercial buildings and the like do. There are many very good firms out there - depending on your location. I would determine the firm based on an appraisal of their experience and personnel that would do the job. Then, after picking one, bring them in on the planning for the power plant investigation. It is never a good idea to have engineers/clients with no or little experience in geotechnical and what I call heavy civil type work to develop an investigative programme. Do so with the experience of your chosen geotech - the really good ones will not 'overdo' it - there is a lot more at stake; their reputations.

 

[cvg]

rather than selecting your geotechnical consultant based on bids ($) - you should consider issuing an RFP or RFQ and get proposal from 3 or more consultants. Select the one with the best credentials, experience and understanding of the project. Selecting a qualified and knowledgable consultant will also ensure that you get the most value for your money.

As stated above, some states have laws (mini Brooks bill) specifically not allowing professional services to be selected based upon cost. See the following link

http://www.nspe.org/govrel/gr2-4022.asp

 

[SlideRuleEra]

I worked for an electric utility on design/construction of power plant, on "bad" sites. The advice you are receiving from GeoPaveTraffic, eric1037, BigH & cvg is exactly how we handled geotech issues.

As cvg states, geotechnial investigation is often considered "Professional Services" and is exempt from bidding requirements. We would request proposals from qualified firms and do detailed and lengthy evaulations... pricing was just a small part of the selection process.

About the number of borings... 6 sounds like too small a number for a "bad" site. I would expect to see maybe 60. Our firm would issue a small preliminary contract to a local geotech firm to perform this initial investigation. This information would be made available to the qualified firms to prepare their proposals.

The final investigation (by the selected qualified firm) would not only cover the whole site, but also be focused on the locations planned for specific structures, such as turbine/generator, cooling tower, coal handing, water intake, etc.

http://www.SlideRuleEra.net

 

[Ron]

Shadmani...I gather from your post that your "team" is going to do a preliminary geotechnical evaluation on its own.

Unless you or someone on your team is an experienced Geotechnical Engineer, you shouldn't attempt this, even for preliminary siting studies. A preliminary geotech investigation might be more important than the final....and both require seasoned evaluation based on experience and specialized education.

Hire a consultant (but don't bid it)

 

[shadmani]

Folks, tons of good information and point well taken. thanks a bunch for your replies.

Based on the responses and our team's own assessments, we have hired an experienced geo-tech engineer (in-house resource) who has thoroughy worked in the area to lead this effort.

Plan going forward is to do a site topo and an initial geo-tech survey as means of due diligence before we buy the land (before we start negotiating with the local community for land, this is Africa).

Thanks again

 

[BigH]

I found a copy of Donald Taylor's 1948 Fundamental of Soil Mechanics (remember the Taylor's curves for slope stability?) - just as reinforcement to what shadmani has learned here:

"Preliminary explorations should be conducted at pratically every site which is considered for a structure of any importance; . . . Unless the underground conditions are well known and are of favorable nature, preliminary borings usually should be obtained even before the purchase of the site. They should be made by a reputable firm, and the expense involved may be considered money well spent."