Wednesday, August 25, 2010

Soil Investigations: August 4-14, 2010

As part of site selections for TEREP, we did some preliminary soil investigations on three sites. Since hiring a geotech company to come out and do these investigations would cost a lot of time and money, we did them ourselves, with equipment from Andalas and UNP.

August 4, 2010 – UNP
UNP (Padang State University) is one of the most promising sites for the TEREP project so far. So we borrowed a hand auger and a lab technician from Andalas University to go do the investigations. But Andalas is really far and the equipment is heavy. We really needed either a car or at least two motorbikes. We had a car for the morning and only one motorbike for the rest of the time.

There were only three of us but the lab technician really knew what he was doing so we started pretty fast after we got to the site. But less than a meter into the ground, we hit a lot of gravel. The hand auger cannot penetrate the layer of rocks. We were then told that most of the university sits on a layer of fill about a meter deep. We had only hoped to go down about 2 meters deep in the first place. We poked around some more after lunch but got no success. I took a sample of the fill and we're hoping do grain size analysis on all the samples very soon.

August 5, 2010 – Seismic CPT
We had heard from Adrin Tohari at LIPI that UNP has a Seismic CPT machine at their campus. This CPT machine looks like all the other ones in this region. It is a Sondir-type machine that has a hydraulic (I think) motor attached to it. There is no truck involved. The reaction for the machine seems to be just the motor. The special thing about this machine is that it has the capability of doing seismic wave tests.

We were able to verify its existance. But it is currently sitting in storage at UNP because no one knows how to use it. It's such a shame because it is probably the only machines in all of Sumatra that can do both CPT and seismic waves. I contacted the company (Geomil) in the Netherlands and they sent me some instructions. The representative said that the machine is very similar to other Sondir machines so that someone experienced with those machines can operate this one with no problems. They also gave me a contact for a company in Singapore. It would be nice to get this machine up before we leave.

We also got permission to borrow (rent) UNP's hand auger for more soil exploration. The equipment at Andalas turned out to be unavailable and really far from where we want to do investigations. So we managed to borrow the equipment along with three undergraduate students and two motorbikes for the next two days.

August 6, 2010 – Terminal Lubuk Buaya
This site is a very swampy field with some overgrown vegetation and lots of children running around. The watertable is very high, at around 40cm from the surface. Because we did not have a GPS or surveying equipment, we paced out the field using the neighborhood houses as our references.

August 7, 2010 – Basko River Site
This is the site that the ESW Spring 2010 TEREP Design Team (aka Lil Bermie) did the conceptual design project on. This site is across the river from the Basko Hotel, a major landmark in the city.

The investigations went a lot more smoothly because everyone knew what they were doing. We hit a lot of obstructions, mostly large gravel. We managed to finish by lunchtime. We went out to lunch together afterwards. The short day and food was much appreciated by everyone since it was Saturday!

August 13 and 14, 2010 – Grain Size Analysis at Andalas
We collected 13 soil samples total. We dried them in the tiny oven in the soils labortaory at Andalas. This lab seems to be heavily used by students working on projects even though it is summer vacation. After drying, we put them through a sieve shaker and weighed each sieve to determine the grading of each sample.

The Report
I have organized my notes into a report on this preliminary site investigation. This can be found here:

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