HAMMERED??? WHY NOT SCREW? Part 1

HAMMERED??? WHY NOT SCREW?

By Rodney Appleby, New Business Manager

PART I: The stuff you can see and touch.

Often in the feasibility stage the pros and cons of bored piles vs timber piles vs UC piles vs pad foundation get weighed up and compared.  Ultimately, the decisions we make have to work on a technical level… and then be economically viable.

Piling can literally be as easy as drilling a hole and filling it with concrete! But the times it’s not that easy (as in 99% of the time), if you’ve not done your homework, and you chose the wrong technique, you will be riding the horse of pain off into a lonely sunset.

Let’s say you had decided driven UC piles were the way to go…  But did you consider screw piles?  And why, or when, would a screw pile be a superior option?

MATERIALS: 

A pipe compared to UC’s ($/m) – it’s relatively similar. 

The key ingredient here is lead time!  If you’re doing a big job, to keep the costs down, you’ll have to order from China, Indonesia, Korea… wherever… but the Contractor will always tag a 3 month lead time before they can start.  If it’s a smaller job, then they might buy it from Fletcher EasySteel off the shelf, but then you’ll be paying a much higher rate.

Technically, the same thing applies to screw pile pipe…. unless you’re Piletech… Piletech holds between $2M-$3M worth of stock (both pipe and plate) in our yards so that we can turn on a dime, and get your project started – whilst keeping costs low because we bought in bulk some time ago.

Piletech Screw piles = less lead time + cost savings.

BIGGER PLANT = BIGGER $$$: 

For small piles the plant will be similar.  But deeper piles with larger loads require larger drop hammers and leader frames, or vibro-hammers, and a crawler crane.  This means:

·         More upfront costs – as crawler cranes cost between $10k-$30k to mobilise,

·         Take 1 day to mobilise and 1 day to demobilise,

·         Cost around $2-4k per day more than typical screw piling plant, (considering all site plant and labour).

·         Reduce the area available on site, so no room to “swing the arms” safely, and thus…..

·         Piling productivity will drop. We regularly install 10-20 piles a day to 24m, and would estimate being 20-30% quicker than similar length driven UC’s.

o   Note: each day more = another $2-4k the client will have to pay for.

Cranes and leaders typically costs more per day than screw piling, with more “one-off” costs.

THE FOOTPRINT

Crawler cranes and leaders?  On a small site even turning becomes an issue.

Screw piling plant is smaller, quicker, nimbler, easier, and safer!!!

ENVIRONMENTAL & TMP:

Often contractors will pre-drill a starter hole to help stand the UC’s upright.  If so, make sure you’ve allowed to handle the spoil, and cart it off site.  Erosion and sediment control is a major with wet surfaces.  It gets tracked out on to the road, and into drains. Silt fences, wheel washing (man + waterblaster), and traffic management all cost more money.

Contaminated spoil… new Work Safe H&S rules state the client, consultant and contractor need to be actively managing this. Tip fees, additional PPE, handling, cartage all cost more money.

If you don’t manage these the council shut your site down, with fines and even convictions!

Screw piles = no spoil = no ground water = no silt controls = no potential environmental incident.

Screw piles = no spoil = no unforeseen contamination variations = no H&S incidents.

Screw piles = less trucks + no spoil = no wheel-washing = less TMP $$ & no potential incident

CONNECTION DETAILS:

Another potential hidden killer.  Piling contractors often tag out of cutting the piles to height, and then welding nelson studs, or top plates on.  At $200-$500 per pile – this will chew a hole in your profit if not allowed for. 

Screw piles typically have a few bits of rebar coming out of the pile which are concreted in.  No sweat, and allowed for in our costs.

Make sure you allow for connection costs when comparing apples and pears.

So hopefully by now you’re starting to get to thinking that you’ve got nothing to lose by asking Piletech to give a free Rough Order Cost to see if they’re within the ball park of my driven UC pile design. 

Tune in soon for “Hammered? Why not Screw? Part II:  The stuff you can’t touch...”

Look Before You Leap

William Brown - New Business Manager

In New Zealand we’re lucky to enjoy a wide variety of outdoor environments – mountains of rock forced up by earth movement, ancient forests, rocky rivers carrying stones and sand onto open plains, wetland areas, sandstone cliffs and beautiful sandy beaches. As much as we like to get out in these environments, we also like to build in them, and the ground beneath our feet can be as varied as the view from above.

If you’re building, you will probably be expected to get a geotechnical report, but how do you know that your report will be enough to design the foundation that holds up your building, and minimise the chance of nasty surprises (and hidden costs) when you start building?

Something that we often see when a customer first makes contact is that their current geotechnical investigation isn’t detailed enough to design deep foundations, and more investigation is needed. Often this is a valid approach – geotechnical investigation can be quite an iterative process and the first round of investigation often focuses on shallow foundations – why would you look deep if you don’t need to? However, often the need for additional investigation comes as an unplanned expense and time delay, which people could do without. Choosing a geotechnical engineer who is familiar with local conditions can be helpful to reduce surprises in this area, as they may have an idea of what foundation types have worked in your area in the past.

So why bother with the additional investigation?

The simple answer is so that you know what you’re dealing with before you start building. Is that ‘hard’ layer 7 metres below the surface strong enough? Is it thick enough? Does it vary in depth and thickness across the building site, or does it disappear altogether? Will the ground liquefy in an earthquake? Just as rivers meander across the ground, conditions underground can vary from one side of a building to the other. Other times the ground beneath can be quite consistent. Although a geotechnical investigation is only ever an indication of what lies beneath, the more information you have the clearer this picture becomes.

At Piletech, we’re happy to work with your geotechnical engineer to make sure the right information is gathered, saving you time and money, and helping you to identify what lies beneath so that you can plan this into your build.

The early bird catches the worm

James Wood – Piletech Manager

So why would involving a sub-contractor early benefit my project?

The past decade in the New Zealand Construction market has seen an evolution in how Clients procure their assets: from the ‘entry price trumps all’ tendering market to the-focused-on-the-end game procurement models of design and build, Alliancing and latterly Public Private Partnerships. This progression has typically delivered greater value through early (and later) involvement of the Contractor to ensure alignment and delivery of the key project drivers.

Typically, screw piling is a design and build part of a project’s scope. The Consultant provides a performance specification as part of the tender documentation and a pile design and pricing is presented by the sub-contractor. This is typically completed in less than two weeks; little time is left for value to be added.

However, real value can be delivered through earlier involvement. The input of a specialist Engineering team refines the design through minimising scope, reducing risk and ensuring build-ability. This then flows through to input into the consenting process, procurement, removing testing from the critical path and generally ensuring that the construction phase is the encore rather than the first act.

A significant proportion of our projects, with a variety of Clients and Consultants, are secured through nomination. These Customers understand and trust that value can be delivered to their project through our early involvement. A quick survey around the office shows that these are some of our most successful projects with the best outcomes for clients, Main Contractors and Sub-contractor

.

On the other end of the scale, we are seeing projects coming to market that have been designed for competitive pricing. This is predominantly focused on the rebuild in Canterbury. In these cases there is often little thought given to rationalising overall scope of the project, or understanding of the implications of procurement, the risks associated with poor specifications and overall allocation of piling risks. In many of these projects, Clients will ultimately fail to reap the value they are seeking; the tender phase simply provides competitive tension around what has been put forward in the documentation.

We are continuously finding more areas where earlier involvement provides value to a project. Only last week one Consultant mentioned that they liked working with us because it reduced the time they invest in the piling; they could focus on the subsequent phases of the project, increasing their and the Client’s probabilities of a successful outcome.

Early involvement with a sub-contractor prior to the tender phase can appear counter-intuitive – “How do I know I am getting value for money if I can’t compare a few prices?” However, others have understood the benefits and taken the ‘leap of faith’ - becoming some of our most successful, repeat customers. They understand the overall drivers and ensure that the team is aligned, setting the project up for success.

So, on your next project are you going to be early enough to catch the worm?

We would love to hear your feedback on this or any of the topics in the screw files. Please feel free to post below and we will be sure to get back to you.