Horizontal Directional Drilling

[SAMGLONICON2791]

Our client has asked us to do a geotechnical investigation to evaluate the soil conditions along a planned pipeline alignment. Horizontal directional drilling (HDD) is planned for a stream crossing about 50 feet wide. Directional drilling is also being considered along the entire length of the pipeline - about 8000 feet. Most of the geotech work that we've done was mainly for structural foundation design. What geotechnical information, and parameters will the designers and HDD contractor need to properly design and install the pipe using HDD? We will include: soil classification, gradation, strength, hardness, SPT N-values. We anticipate most of the subsurace soil will consist of detrital coral (moderately toweakly cemented sand and gravel)with some zone of stiff clay. The coral may have some hard zones as well.

 

[Zambo]

Sorry can't answer your question. But what is the pipeline for? what is the pipe material? and what is the diameter?

 

[epongra2]

Detrital coral? Loss of drilling fluids perhaps...

 

[cvg]

water table depth, location of any large gravels / cobbles. Recently, seismic refraction surveys are often being required and can provide a lot of good information not readily available with just borings.

 

[rconner]

You have gotten some good advice. I believe also there have been several papers dealing with pre-construction surveys and geotechnical investigations etc. for HDD delivered to the Pipeline Division of ASCE in the last few years. An ASCE Publications search, as well as discussions with specialists who do this work, may reveal more information that may be helpful to you.