Basement Excavation

[Matt]

Evening All,

Iv been asked to price a job digging out a basement. The secant piling is being installed at the moment which will run around the perimeter wall of the house and Iv got to give a price for excavating and removing the muck within this once its complete. Its a big old lump at approx. 18m x 20m and final depth is 4.1m below the top of the ring beam. Which means about 2200 cubic meters of muck to come out.
It’s in heavy wet clay and the piling rig has made a nice mess of the ground already so theres no chance of working round the perimeter and running dumpers, or even running dumpers in the middle. Lorries for muck away can only get near to the South West corner of the basement, so I was thinking about having one machine getting the bulk dig done then swinging the gear into a pile, and another loading lorries from the pile. Gradually working the machines out toward the SW corner whilst remaining at existing ground level or close to it.

The client is insisting on a 21 Tonne machine working within the dig out and a 13 Tonne loading the lorries. I would have thought that two 13's would get through that fairly quickly at less cost, the only reason I can think of is that it will be easier cleaning up at the end when reaching right down into the corners, over the piling and ring beam.

Is a 21 Tonne Machine going to be more cost effective/ beneficial? Whats peoples thoughts/opinions? Any advice greatly appreciated!

Thanks
Matt

 

[doobin]

If they’re asking you for a complete price then you spec the machines as far as I’m concerned.

I can’t see any sense in the first machine being double the size of the second.

 

[diggerjones]

Why would he insist on any machine. Whats it mater to him. Your price you get any machine you want.

 

[Grifferr]

Maybe a 2 or 3 ton mini in the dig to clean up the corners and edges. Lift it out at the end. You need good access for 220 eight wheelers!

 

[Mogman]

Your job use what you like but if digging virgin clay I would use a 20 tonner has will have better tear out than a 13 tonner,the smaller machine will only be rehandling so easy digging for it

 

[JD450A]

Perfect territory for a 21t long reach Imho.

 

[Stock]

Who is paying the haulage?.................................
A 20 ton will load faster than a 13 ton...................
Me depending on the site I'd look at two 20ton or stone up so as to dig and load with one 20 ton..............................

 

[Gunners]

Having a separate machine on lorry loading is a good call if you get a good service on lorries. Why the client is telling you what machine to use I don't know - as others have said, its your job!
In my limited experience of basement digs but plenty experience of pricing work, its usually the hidden things that sting you - the digging is the easy bit. Road sweepers/ jet washing wheels and groundwater are the two unknowns here really. There must be a ground investigation survey somewhere as the engineer wouldn't design a basement without knowing what the water table and ground conditions are like 4m down. Find that, and see what they found, might of hit rock, high water table etc - vital info for pricing!
With that many lorries going in and out you might find it cheaper to put a bit of base down and keep it clean as crush concrete will go to s**t in hours.
As for digging it, if you don't own any machines big enough then hire the biggest one that you can fit in the job. The faster its done, the more you earn as having two blokes will add up fast. If you own a 13t then you might as well use it.

 

[Matt]

Thanks for all the responses! Lots of good advice.

Not sure why he was so keen to have a bigger machine. I think he wants to push the job along and get on with it as quick as possible so I guess he thinks the bigger the machine the quicker the job will get done, which I understand.
We have a little 2.6 Tonne machine so that can do any tidying up and get lifted out if needed as Griffer said.
Reason for a 13 to load out is it's only rehandling and we have a zx130 and want to make use of that, and it's more than capable of loading lorries all day long, might not be as quick as a 20 Tonner but I'll be saving on hire of at least one machine. 20 tonne machine could be the best bet for the dig for that bit of extra power if the clay gets tough.
I have had a quick look at a soil report when I did the site visit but I'm waiting for them to send a copy over so I can run through it in detail. From memory it was lighter silty clay for the first 1.5m -2m then gradually getting into heavy grey clay. I didn't see any info on groundwater but I didn't have too long to look at it.
They are responsible for wheel washing and cleaning the road as they have plenty of guys on site. Although as suggested there is already a concrete pad big enough and in the correct position for a lorry to sit on whilst loading, so there shouldn't be too much crap getting dragged out.
The road outside is a private road and has plenty of width and a turning area which is ideal. Not sure what the neighbours will have to say about all those tipper queuing up outside though!
Like Gunners said I think one of the main issues could be he groundwater so got to look at that and then go from there really.
He's already had a price for haulage so basically Iv got to beat that. It's going to be on a per load basis as if the ground conditions get wet then the lorries won't be taking as much due to the weight. We normally get good service from our haulage firm so number of lorries would only be a problem if he wants to organise that. If that's the case I'd have to quote based on a certain number of lorries per day as I don't want to be waiting for lorries if I'm on a price and I can't control them.
Cheers
Matt

 

[Gunners]

He's already had a price for haulage so basically Iv got to beat that. It's going to be on a per load basis as if the ground conditions get wet then the lorries won't be taking as much due to the weight. We normally get good service from our haulage firm so number of lorries would only be a problem if he wants to organise that. If that's the case I'd have to quote based on a certain number of lorries per day as I don't want to be waiting for lorries if I'm on a price and I can't control them.
Cheers
Matt

Matt,

Obviously you know the client but from what you have put on here it seems like a classic case of "he already has the figures" and he is just pushing you to beat the quote he already has. As you have implied, if he is providing the lorries you need to be on daywork really as his preferred "cheap" supplier might screw you right over on lorries per day. My gut feeling based on what you have said is theres not a lot of money to be made on this one.

 

[Brendan]

Unless you can control the wagons and are making some money on the wagons to cover any delays of turnarounds, day work would be safest bet.
As Ollie says probably stipulating the machines to check his other quote

 

[BertB.]

I second the 20 tonner minimum but I would suggest going up to at least 25 tonne as it will have better reach at that depth and you won't lose on bucket capacity to get that reach. Now I know nothing on what equipment availability is over there but the tight tail swing machines are quite popular so that might be a good option if things are going to be tight through the duration of the job. I would also advise against rehandling any muck if at all possible and get wooden mats to make a movable temporary haul road if available there so your trucks can back right up to the excavator thus keeping them on a solid surface and hopefully minimizing tracking mud up and down any streets. I imagine this Secant piling is some sort of shoring you have there? If you need to clean up the bottom at all during the excavation maybe see what the availability is on a tracked skid-steer they are indispensable on a job like this if not then maybe a small track loader like a Cat 931. Just my ten cents from digging large excavations in urban environments.

 

[Matt]

Matt,

Obviously you know the client but from what you have put on here it seems like a classic case of "he already has the figures" and he is just pushing you to beat the quote he already has. As you have implied, if he is providing the lorries you need to be on daywork really as his preferred "cheap" supplier might screw you right over on lorries per day. My gut feeling based on what you have said is theres not a lot of money to be made on this one.

You could well be right. Hadn't really looked at it that way until you said. I would only do the job on daywork if he wants to control the lorries, unfortunately like you say, that will mean there isn't as much money to be made on the job. Always good to get some other opinions and different sets of eyes on something so thanks for that.

 

[Matt]

I second the 20 tonner minimum but I would suggest going up to at least 25 tonne as it will have better reach at that depth and you won't lose on bucket capacity to get that reach. Now I know nothing on what equipment availability is over there but the tight tail swing machines are quite popular so that might be a good option if things are going to be tight through the duration of the job. I would also advise against rehandling any muck if at all possible and get wooden mats to make a movable temporary haul road if available there so your trucks can back right up to the excavator thus keeping them on a solid surface and hopefully minimizing tracking mud up and down any streets. I imagine this Secant piling is some sort of shoring you have there? If you need to clean up the bottom at all during the excavation maybe see what the availability is on a tracked skid-steer they are indispensable on a job like this if not then maybe a small track loader like a Cat 931. Just my ten cents from digging large excavations in urban environments.

Matting is certainly something worth bearing in mind, I think it would really depend on how wet it is if the job were to go ahead, as the clay was pretty bottomless when I looked at the job as the piling rig has made a right mess already and was only part way around.

 

[BertB.]

I know getting any dry weather over there is like finding a lake in the Sahara desert but could you have somebody or even do it yourself and at least level the rutted up mud? So its at least half assed flat so it can dry a bit if not be a flat surface on to which your mats could be placed and if needed double up on mats. Only other thing I can think of to make it easier to back trucks up on is using coarse crushed stone or something I saw recently from a logging crew out here use wood chips of which you will need a LOT! lol

 

[Matt]

I know getting any dry weather over there is like finding a lake in the Sahara desert but could you have somebody or even do it yourself and at least level the rutted up mud? So its at least half assed flat so it can dry a bit if not be a flat surface on to which your mats could be placed and if needed double up on mats. Only other thing I can think of to make it easier to back trucks up on is using coarse crushed stone or something I saw recently from a logging crew out here use wood chips of which you will need a LOT! lol

All good ideas, I'll see how it plays out and then if we get the work we can make it work from there.

 

[Danny]

Just make sure you have a big enough pile to load away every morning as they all like turning up at once