specification for geotechnical investigation 2

[steve1]

I am a structural engineer who has been assigned the task of writing a specification to procure geotechnical services related to an underground natural gas pipeline of approximately 3 miles in length. I'm hoping a geotechnical engineer can steer me in the right direction. The issues that I believe need to be addressed include: How ofter should borings along the pipe route be taken? What is the appropriate type of geotechnical report to request (Data Report, Interpretive Report, Baseline Report, etc)? Should the report be included with the bid documents?

In addition to the above, is there a website where I can download standard geotechnical specifications related to this type of project?

Thanks in advance for your assistance.

 

[dlhod]

For a project of this length, a specified spacing of borings along the route could add quickly turn into high number of borings - and could still miss where the borings should be. I'm not sure what area of the country you are in, but certainly for a pipeline, the presence of bedrock would be of interest. No matter what the spacing, locating borings at the topopgraphic highs and lows (and other anomalies) would be useful. Auger probes without soil sampling can provide information about the presence of bedrock at a lower cost. Soil sampling should be performed in some of the borings to provide information for the contractor concerning the type of shoring that may be needed. Extended groundwater levels are also important, so temporary wellpoints may need to be established (if groundwater is believed to be in the depth of excavation for the pipeline).

I have used geophysical methods (such as resistivity or simple refraction) to provide better coverage of a pipeline alignment, with borings used to augment the findings. I've seen boring spacing be as close as 250-ft to as much as 1000-ft. The key thing to remember is that it doesn't necessarily have to be the same along the alignment. Allow for variations where the conditions are likely to be irregular.

In terms of the type of report to request, I would expect to provide a report that interpets the findings with respect to geology, soil conditions and how the conditions will influence construction, as well as the long term performance of the pipeline.

You might try the ASFE website for sample RFPs (

http://www.asfe.org)

 

[steve1]

Thanks dlhod. Your information was helpful. I went to the website you suggested, unfortunately they no longer have in stock any copies of "Terms for Geotechnical Engineering Services". Would you know of any other places where I can obtain a copy of this?

 

[Qshake]

Try ASCE's website and bookstore or publication list. I recall seeing another document on procurring geotechnical services.

http://www.asce.org

 

[steve1]

Thank you qshake, I found exactly what I was looking for at the ASCE web site.