Working in Brunei

8 - 11/8/06

Site 1


This was the first ever site that I've worked on in Brunei Darussalam. Pretty interesting site where soil, sediment, groundwater and surface water are required to be sampled. And this was my first site that I had actually used a Van Dorn sampler for surface water sampling, and improvised a method for sampling soft sediments at the bottom of a pond. Completed all soil/sediment/gw/sw samplings with the help of colleagues in the record time... of three working days!! But it was pretty scary on the boat when we were carrying out the sw sampling and sediment sampling since we can't see the bottom and the overgrown underwater weeds keep 'grabbing' our equipments that were lowered down into the pond for probing/measurements.

Well, for the samplings within the pond area, the initial idea was to build platforms to 'reach' out to the sampling points.... but then again it will be very expensive (materials priced in BND) and building 4 or 5 platforms will be too time consuming. And we are a bunch of environmental sampling experts and not foundation engineers, where we need to calculate the proper strength of the materials and structure (platform) before we could actually put our weight on it. And then there was also an idea to build a pontoon... but then again, it won't be as stable as a boat. So since I am the de facto project manager of this site (and my colleague chose to be in charge over the 2nd site), we decided to go on a boat with peddlers, to carry out the sediment and sw sampling. For the sediment sampling, we tried using Ekman grab/dredge/bucket, but the soft sediments 'disappears' before we could lift the sampler out from the surface of the pond, and that warrants for plan B. But what's the plan B? No such plan.... heck... so in the first day of sediment sampling, we failed to retrieve sufficient sample... not even in decent volumes to fit into a single soil jar!

Pondered hard overnight over the predicament (sediment sampling), and suddenly the sampling mechanism of 'geotube' and obtaining undisturbed sample via Mazier sampling (from experience working at KL Pavillion site for 6 over months) came into the picture and voila... I took my chances and ordered 4-5 nos of 3m lengths of 1.5" dia uPVC pipe the following day, got on the boat, used a handheld GPS to get to the sampling points, whacked the short uPVC into the sediment 'beds', cap them (liken to close the tip of a straw to retain the liquid inside), pull them up, cap and seal the bottom. The next step is to drain out the water column inside the uPVC, else the water will mix the sediment up and it will be an impossible task to differentiate the sediment at the top surface and the required sample at 0.5m below it. So I took a small drill (that was mean for riveting) and drill some holes within the water column in the uPVC pipe, but very near to the top surface of the sediments, for draining the water out from the pipe. Mind you, this wasn't an easy task because the pipes aren't transparent, so I had to rely solely on my sound judgment. So after the draining task, the next step is to remove the sediment samples from the pipe... easy except for one... the rest is just like laying logs in the toilet bowl, if you know what I mean ;-p

GW sampling - easy lar, same as soil sampling. Surface water sampling is a bit tricky, because we're in the boat somewhere in the pond area... windy at times and it would be an arduous task to attempt rinsing or decontaminate the sampler after each sampling (at three different depths, if my memory didn't fail me lar). And some more challenging because there were so many bottles to fill up i.e. preserved and unpreserved plastic bottles (for testing of metals and inorganics, I think), glass 500ml and amber 1L bottle (more bottles for duplicate).

Drilling and installing monitoring well is somewhat challenging, since the site is predominantly underlain by silty fine SAND with high water table. And mind you, we did not engage a drilling contractor for this job (PM quoted less to build bridge with the client). But with Makkal Sakti of few Filipinos, we managed to pull this through and wrap up all the work by the third day.