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Author: Subject: Advice on Digging an Inspection Pit.
Antnicuk
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posted on 22/9/10 at 06:29 PM Reply With Quote
Advice on Digging an Inspection Pit.

I am going to start building a workshop next week and part of the plan is to put a pit in. I am hiring a digger as i don't like digging!

I would much rather have a ramp but i dont have the height.

Just looking for advice on the best way to do things like:

Shape
Size
Depth
Lighting
Covering
Floor
Damp/water proofing.
Floor jack (like MOT ramps have)

Any advice will be greatly received





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jacko

posted on 22/9/10 at 06:40 PM Reply With Quote
Put steps at both end pit's are very dangerous

We have just had a new pit fitted at work 45ft long
The hole was made and the pit was delivered it came as one big tank 3mm steel with all the lighting etc

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iank

posted on 22/9/10 at 06:46 PM Reply With Quote
Check with your insurance company - I've heard they load the premiums if you have a pit (or use it as an excuse not to pay should your workshop burn down and you haven't told them).
The problem is they can fill with petrol fumes which can make them explode, or exhaust fumes which isn't a good thing to walk into.





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StevieB

posted on 22/9/10 at 06:54 PM Reply With Quote
You'll be wanting an extraction/ventilation system.

Worth checking building regs on the matter, as well as any other applicable laws.

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coozer

posted on 22/9/10 at 07:03 PM Reply With Quote
If I remember you need building regs cause A) you may interfere with close house footings.. and B) maybe you need to ask the water authorities...

Now, this is all a few years ago, it may be thaey are banned these days.

I have a pit in my garage which is reinforced with brick sides but fills up with water when its raining. Thats why I think you need to ask about the water table.. not sure mind.

If in doubt, dig it and don't tell anybody but! don't go any where near with oxy-acetelene bottles!





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interestedparty

posted on 22/9/10 at 07:17 PM Reply With Quote
If this is for a kit car then IMO you don't need it. Find a sturdy way of supporting your car so the wheels are about 2 feet from the ground, and buy a big jack that can lift it that high, then get a crawler, MachineMart do a really good one that converts to a seat.





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zilspeed

posted on 22/9/10 at 07:55 PM Reply With Quote
The most useful pit I have ever seen has the best bit of bodgery you'll find anywhere.
One of the timber boards for the top of the pits is actually a steel channel. It sits on top of two hydraulic rams and when not in use sits flush with ground level.

The rams are powered by a power steering pump which is in turn powered by a 240 volt motor. This is all controlled by a valve block.

Drive the car over the pit, lining the jacking points over the steel channel, on with the hydraulics, ease the channel up to the car, make sure everything's positioned, then take up the strain and away you go. Lifts the car up about 3 feet on the air. In conjunction with the pit, you have access to the car and you can stand up below the car - and it will work in a domestic garage. No need for a ramp.
All done via good old fashioned wombling.


[Edited on 22/9/10 by zilspeed]

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Antnicuk
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posted on 22/9/10 at 08:10 PM Reply With Quote
^nice, although not sure i would trust myself to plumb in the hydraulics to ensure it wont drop on my head!

thanks for the input guys.

I was thinking of making it T shape so i can get in at the front end with ease.





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rusty nuts

posted on 22/9/10 at 08:26 PM Reply With Quote
Don't get in the pit if you even suspect there are any petrol fumes in it . Petrol fumes will knock you out!!! Don't do any welding in a pit
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bigbravedave

posted on 22/9/10 at 08:58 PM Reply With Quote
The best advice I cud give is to make sure it has a sump dug in one corner with a pump in it. I reguarly work in pits with a few inches of water in, I wouldn't like to drop an inspection lamp when ankle deep in water!

I usually leave an inch in when doing oil changes, If you drip some oil it floats, then just drop a drag on it afterwards.

Pits can be very difficult to keep dry, I have seen steel liners do impressions of cannel boats and rise up lifting concrete floors with them, I kid you not! my own pit has alot of fibreglass lining it, yet the water pressure is sufficent to make its way through incredably slowly but will collect an inche a week in winter its a good few feet below the water table

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britishtrident

posted on 22/9/10 at 09:10 PM Reply With Quote
These days it is very difficult to get approval for a pit, Radon gas is another reason why they are discouraged in some areas.





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Antnicuk
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posted on 22/9/10 at 09:23 PM Reply With Quote
i was planning a mesh sump, and a small pump.





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hobbsy

posted on 22/9/10 at 09:29 PM Reply With Quote
Sorry to hijack slightly but any paint recommendations?

Recently moved house and it has a pit outside under a car port.

I've not been down it yet but it all seems dry (covered with wood across the top).

I could do with a lick of paint to brighten it up though.

I was thinking the same single-pack PU anti-slip paint (red) I used in the garage.

Is this stuff ok. I asked a supplier on ebay selling "pit paint" how it was different to single-pack PU garage floor paint and he couldn't really tell me - however "pit paint" seems to be about twice the price.

Need some lighting and outdoor power and air lines

The sump and pump might be a bit tricky.

How big do you need to make the sump?

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Dingz

posted on 22/9/10 at 10:19 PM Reply With Quote
I made one once when I built a garage, it was in heavy clay soil and the water table was very high in winter. I lined it with 2 layers of poly, then poured a concrete base and bricked it up to the floor level. It was fine for about a year then it would slowly fill up to about 4 inches from the top! must have punctured the lining somewhere. So when I wanted to use it there was a lot of water to shift! The idea of fitting a pump is a good one.





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BenB

posted on 23/9/10 at 08:12 AM Reply With Quote
I would also suggest fitting a sump at one end with a pump. If you get a pump with a float it will automatically pump out any water as / when it collects.
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designer

posted on 23/9/10 at 08:19 AM Reply With Quote
Can't you buy a moulded pit you just drop into a hole? Sure a company advertised in the kit press when I bought them years ago.
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wilkingj

posted on 23/9/10 at 09:24 AM Reply With Quote
Mate of mine fell through his pit boards only a month ago. The boards were old and had rotted with the damp.
He is in a wheel chair now, Broken leg and Fractured pelvis and ribs. He is 60+ so its hit him hard.

Take ALL the safety precautions.
You dont think about foul air aphyxiating you, and it can happen as its heavier than air, and collects in the bottom of pits, and fills it up.

I know, I have spent 40 years on BT and have had safety briefs and training on it over those years.
I felt really silly standing on a busy roundabout 30 years ago, hauling up and emptying out what appeared to the public to be empty buckets. (Actually full of foul air)
Nowadays its a pertol driven ducted fan dropped into the manhole and cleared in a couple of minutes.
BTW by Foul Air I mean Non-Oxygenated Air, not smelly air.
Same precautions apply with a pit.
You get overcome and fall to the ground and suffocate in a gas you cant see.

Same for flamable gasses. Some are heavier than air, and are just in the ground naturally. The collect in places where there is least resistance of travel, ie pits and pipes.

Its why you often see a BT man sitting at the top of a manhole whilst his mate works below. Looks like he is wasting time sitting about. Its not!. he is the safety man for the bloke downstairs in the manhole.


I know this sounds Draconian advice, but I have seen first hand what happened to a colleague in Peterborough when a manhole caught fire. He ended up badly burned, BT also used him in a safety film.. The results were not very pretty.

Also do the construction side properly. You can soon die in a cave in, again from aphyxiation.

So PLEASE take ALL the precautions and check the rules and regs.
If you are going to do it. Do it properly.
No amount of lo-cost penny pinching will be able to compensate for any injury or the loss of a life (or possibly someone elses)

Best Advice would be to buy a Two Post Lift.
Probably not a lot dearer in the long run, and a darn sight safer.



EDIT:
Just thought of something else..
Be especially aware of the Gas issue if you Mig weld with CO2 (not sure about Argon). It is much heavier than air, and will drop to the floor and collect in your Pit. You cant see, feel, taste or smell CO2. and it WILL Kill you if you get in a pit full of it, and no one to pull you out or to get help.

Just be Safe, we dont want one less member on LCB do we!

[Edited on 23/9/2010 by wilkingj]





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2. Never take life seriously. Nobody gets out alive anyway.

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scudderfish

posted on 23/9/10 at 09:56 AM Reply With Quote
Before you use the pit, always drop a lit match in. If it goes out, the pit is full of CO2 and you will die. If it blows up, it was full of petrol vapour and you are dead. If it sizzles and goes out, your pit is full of water.
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interestedparty

posted on 23/9/10 at 12:26 PM Reply With Quote
Still think some decent chassis stands and a hi lift trolley jack make a lot more sense. Movable too!





As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!

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