Cambodia dam project - equipment needed 4

[EWBCambodia]

Hello,

I am involved with the New York chapter of Engineers Without Borders, a non-profit humanitarian organization. We have recently taken on a fast paced project in Cambodia at the Balang Commune near Siem Reap. Our team is working to construct a concrete dam to replace a centuries old earthen dam that washed away during the rainy season of 2000.

We will be conducting some in-situ soils testing in November, and all equipment will have to be carried to the remote site in two backpacks. Preliminary information indicates the soil varies from fine sand to sandy clay, and the water table is quite shallow.

We have located some of the testing equipment for the site assessment trip, but we are having some difficulty locating the following equipment:

+ Hand held field vane shear testing equipment
+ Drive point piezometers
+ Sand cone apparatus (for direct density measurement)
+ Soil resistivity meter (to estimate soil corrosivity)

If you have any of this equipment, or know someone who does, it would be a major help to our project if we could borrow or rent during November through December.

I hope you have a moment to write back.

Thanks and best regards,
Ryan

Ryan Woodward
Bridge Engineer

HNTB Corporation
5 Penn Plaza
6th Floor
New York, NY 10001-1810

Tel (212) 594-9717, ext. 7047
Fax (212) 947-4056

http://www.hntb.com

http://engineerswithoutbordersnyc.blogspot.com/

Project Summary:
Our organization was approached to help bring preliminary dam repair plans to fruition by checking a local engineer's design, inspecting site conditions, coordinating the construction effort, and monitoring quality controls during construction. Our goal is to ensure the dam is safely built according to specifications and to prevent a future dam failure. In addition, we will make every effort to use local labor and materials, and we will recommend a locally operated inspection and maintenance program to ensure the continued safety of the dam.

Aside from creating an opportunity to help restore a sustainable economy for the Balang Commune, we see our project to rebuild the dam working hand-in-hand with a greater effort to raise awareness of Cambodian issues while empowering the community to create real, positive change. We hope you will find an interest in our project.

We have made much progress reviewing the design documents, and will soon visit Cambodia to evaluate the site before construction begins late this year.

 

[DMcGrath]

I don't have the equipment, but I would suggest using a drive cylinder method for measuring soil density rather than a sand cone. Both methods are relatively "low tech", but the drive cylinder method (ASTM D 2937) removes some of the human error seen in the sand cone testing. Neither of these methods will work worth a hoot in sandy or gravelly soils.

Don't forget both of these methods require an oven to dry the sample and scales to weigh it. You'll need these things too.

 

[EWBCambodia]

Thanks DMcGrath,

As you suggested, I'll look into drive cylinder method as an alternative.

We're planning to obtain moisture content by the direct heating method (ASTM D4959).

Thanks,
Ryan

 

[oldestguy]

Do you have any mechanics in your firm? Making the vane shear tester is a simple project, done in the home shop.

You measure torque with a torque wrench from an auto tools supply place, and you weld a "spare" socket to sections of 1/2" steel pipe to transfer the twist to the vanes.

Size the vanes for the consistency of the material you wish to measure. I made one 4" by 8" for soft peats, 2" x 6" for most clays where you can push the thing in.

Develop a calibration from these dimensions, depending on whether you use the upper "surface" of shearing or not. The Bureau of Reclamation Designation E-20 (from an old book) has their dimensions as 2 x 4, 3 x 6, and 4 x 8 inches, if you want to look for some stsndard. However, the question of disturbance led me to use a longer vane that these for somewhat better "accuracy".

The formula for the Bu. Rec. sizes is:

S (psi)= 3*T("p)/28*Pi*r3 That is r cubed. where r is radius in inches.

Does not include shear resistance on top surface.

 

[TDAA]

DC is a good choice. The hammer could be a bit big and heave though. The hammer itself is not important. You could have a plate made to fit the top of the cylinder with a handle/striking surface, and use a 4# sledge (which I am assuming you are bringing anyway).

 

[EWBCambodia]

Thank you oldestguy and TDAA.

I don't have access to a machine shop, though we will be fabricating some of the parts. We'll purchase some plumbing equipment and a drum to fabricate the apparatus for measuring porosity (conductivity).

We have borrowed an auger from AMS (ams-samplers.com), and portable shear vane tester from Rutgers University. I'll use your suggestions to fabricate an extension for the shear vane tester.

We have borrowed a digital scale from Princeton University. We'll use it to measure soil density with the Direct Heating Method ASTM D4959 (dry the soil using a camping stove).

Thank you everyone for your kind advice. We will depart for Cambodia November 10th.

 

[BigH]

Watch out for landmines and UXO - in my Laos job we ran into over 20 500 pounders within the highway's right-of-way. Luckily we have very little contact with land mines. In your situation, be prepared to "wing it" - I would suggest that you try to get the first 30 pages or so of Malcolm Bolton's book titled "A Guide to Soil Mechanics". In these pages he presents very good examples of doing "real engineering" using the most primitive of tools and analytical methods. Cambodia will not be that 'backward' - there should be a number of ADB and WB road projects going on. Get chummy with some of the expat engineers on these projects - especially if there is one nearby and you might be able to find or finagle much of what you need by your networking. Equipment and/or testing wise - and, of course, work-chats.

 

[EWBCambodia]

BigH,

Thanks for your comments, we'll be sure to be cautious.

We don't have Bolton's book in my office, and it is out of print, but I will definitely track down a copy.

Regarding networking with engineers on other projects nearby, I absolutely agree this can be helpful for so many reasons. In fact, we've just made contact with the International Labor Organization. They worked on over a hundred projects like this one back in the 90's.

Would be interesting to hear more about your projects in Laos as well. I'll be heading there after Cambodia.

Regards,
Ryan