THE IMPORTANCE OF GEOTECHNICAL SURVEYS
It relates to just about everything in our lives from friendships to marriages; garden sheds to high-rise tower blocks. If it’s not built on a strong foundation, it won’t last long when things get shaky.
Here in Fiji we live on shaky ground made up of an archipelago of big and small islands, some are large volcanic mountains others are no more than a sand spit. Some of us prefer to live on top of a hill while others want the lap of the ocean on our doorstep. Regardless of our preferences we need to know that our house will keep us safe and has the best chance possible of surviving the worse disasters Fiji will face in the future.
One way is to ensure that your new home is cyclone rated. Anyone wanting finance for a new home or cyclone insurance cover will need to prove that it is engineered adequately for cyclonic wind pressure, and that it is built to a certain code and standard. Cyclone certification will only be given on inspection and approval from an engineering company recognised by the ICF (Insurance Council of Fiji).
However, all of that will still be for naught if the foundations of your house move during heavy storm or earthquake activity. The result of such movement could mean no house left to save, or severe structural damage that will require major, and expensive, repair work.
So, how do you prevent that? How do you ensure your new home has the best chance of standing up to a major catastrophe? By engaging a professional company to undertake a geotechnical survey of your site before you excavate or build anything on it.
A geotechnical survey can determine what is happening underground, what your site is made up of and how solid it is.
The geotech team from PACAu Fiji Limited
surveying a site for drilling
Here are some of the key findings that a geotechnical survey will establish:
- What is the level of soil cover, and what type of soil it is
- Whether there is rock formation below the surface and how stable it is
- Whether there is liquid seepage such as natural water springs or run off from mountain terrain
- Any evidence of slips or previous unstable earth movement
Such information is critical to the design of your foundation system and can even determine best placement of your new home on the site. What’s important to us is the view or where our house sits in relation to neighboring properties; what’s important to a Geotechnical Surveyor is where the most stable and suitable place is for your home so you still get those views with minimum risk of movement.
Collecting soil samples for analysis
The results of a geotechnical survey will help to determine what type of foundation system is best suited to your site and the house you wish to build.
- If you want to build a concrete block house it will be much heavier than a timber one – is your site suited to this? Can it take the extra weight without sinking?
- Do you want your house elevated on poles? If so, how deep do the poles need to be in the ground for maximum stability?
- Do you want a concrete slab foundation? If so, how wet is your site? Does water collect in puddles after heavy rains? Are you close to a river or waterway system that rises during the wet season? This can lead to flooding and subsidence if not properly surveyed beforehand
What type of soil is your land made up of?
Breaking hard ground
Once the house is built a swimming pool is usually the next thing on the wish list. A pool above ground holds an immense amount of water that equates to a lot of extra weight that has to be held without sinking. If your pool is below ground you need to know what you’re digging out and whether it is suitable as a big bathtub full of water, kids and the family pet!
If you have already obtained a geotechnical survey report of your site, you will be able to determine the best and safest place to put your pool.
Road damage after heavy rain
Some people are of the view that geotechnical surveying isn’t necessary as there are already houses in the area that survived Winston and came out unscathed, so presume their house will be safe too. Other people view it as an unnecessary expense and just want to get on with the project as quickly as possible. However, in the last 6 months alone Fiji has experienced more frequent and larger earthquakes than ever before. Add to that increased cyclone activity in the Pacific region, rising sea levels and global warming a real threat and you can easily see why it’s now more important than ever to know what you’re building on and ensure your house foundations are strong enough when things get shaky.
DID YOU KNOW
Pacific Property Solutions partners with experts in all areas of construction and can put you in touch with the right professionals so you get the best advice possible before you sink your life savings into the ground.
If you are arranging a kit home through PPS and have obtained a geotechnical survey report, we can have the foundation system designed in New Zealand at the same time as the working drawings. This is a huge benefit to you because this means your foundation system will be designed specifically for your house, and for your site. A One Stop Shop!
If you are building independently, we can still offer advice on foundation solutions to suit your site before any work commences.
Gareth is a Director of Pacific Property Solutions Pte Ltd and is also a Professional Quantity Surveyor and Member of the New Zealand Institute of Quantity Surveyors