Hole digging

This is the hard part of fencing! Bear in mind the following:

• Make absolutely sure you’ve chosen the best site for the post before you start to dig. See the section on planning the fence.
• For group work, have available sufficient numbers of the correct tools for the job.
• Wear gloves if you’re not used to digging. Using a crowbar, which quickly gets dirty and gritty, soon causes blisters.
• Don’t make the hole wider than is necessary. Firstly, you’re making more work for yourself, and secondly, the post will be less secure than in a narrow hole. If the hole is wide enough to stand in, it’s much too wide! Keep the sides vertical.
• In most soils you will be able to tamp back in more soil than you dug out, in spite of the hole now containing the post! You may then need to dig a shallow pit nearby to provide enough fill.
• On urban sites and near buildings, ensure that checks have been made for the presence of underground services.
• If working on very steep slopes, a temporary ‘step’ is useful for retaining the spoil.
  
• In long grass, old fertiliser sacks or similar make it easier to shovel up the spoil.
• Separate the top and subsoil, and throw roots and rocks to one side.

Procedure

1. Mark with a spade the size of the hole. This should be the diameter of the post plus enough room to use the punner on at least three sides of the post. Aim to place the post so that the greatest pressure is against an undisturbed face. A hole of about 400mm (16″) diameter is suitable for a typical straining post. If using a garden spade and shuv-holer in loamy soil or soft clay, a square hole is easier to dig. A combination of crowbar, trenching spade and shuv-holer in difficult ground will normally produce a round hole. In either case, keep the sides as vertical as possible.
   
2. Dig down as far as you can with the spade, removing the fill and piling it up far enough from the hole so that it’s out of your way and won’t slide back in, but near enough for ease of action. Some people find it easier to dig by the sequence shown below. Concentrate on half of the hole at a time. Especially as you get deeper, it’s easier to prise loose the second half of each layer using a crowbar or spade.
   
3. Once you have got too deep to remove soil with the spade, start using the shuv-holer to remove the loosened soil. Except in very soft soil, sand or peat, don’t use the shuv-holer for actually making the hole, as the blades are not strong enough.
4. Hole-digging is best done as a two person job, with one person using the spade or crowbar to dig, and the other removing debris with the shuv-holer as the hole gets deeper. This then gives each person a rest while the other works.

As a guide at which to aim, the Forestry Commission allow 56 minutes for two men to dig a hole 850mm (34″) deep in soil of clay with a few stones, fit and firm the post and refill the hole. Conservation volunteers may take a little longer!

Soft soil

In deep loam or soft clay a deep narrow hole can quickly be made using a post hole auger. These are available in various sizes and types. Depending on the soil type and dampness of the ground, screw the auger down about 200-300mm (8-12″), and then lift it up, bringing the soil with it. If you can’t easily lift it up, unscrew the auger a short way to lessen the load, and then lift it out. In wet clay soils you will need a short stout stick to clean the blade frequently. For hole diameters larger than the auger, make two or more holes immediately next to each other, and then clean out with the spade and shuv-holer.

Wet soil

If the hole starts to fill rapidly with water while you are digging, stop and consider the alternatives.

If possible, move the site of the straining post or turning post onto ground which looks as if it should be drier. Try a few test holes with a crowbar. If it goes in easily and squelches around in wet subsoil, it is going to be almost impossible to get a straining post firm in the ground, apart from the practical difficulties of digging the hole. If there is no alternative drier site, consider using a box strainer, which can give a firm structure even in damp soil.

Alternatively, you will have to dig a large pit and use bracing timbers or stones to wedge the post firmly. This is very laborious, and not guaranteed to be successful.

In many upland areas, fencers select rock outcrops and drill them to fix metal posts (see below), rather than try to secure wooden posts in peat.

The use of high tensile wire is also helpful, as this can be strained over much greater distances than mild steel wire. On some sites it will then be possible to fix straining posts on firm ground, with the fence stretched across the boggy areas.

Rocky ground

This will involve a lot of hard work with a crowbar! A pick can be used for the first 300mm (12″) or so, until the hole gets too deep to use one.

Wear gloves when using a crowbar to avoid blisters. Stand well balanced with feet apart, and use the weight of the bar, loosening the grip slightly on impact. More force can be used as you get accustomed to it. If you have to crouch to use the crowbar in a deep hole, take care not to hit your head with the upper end. If the bar gets stuck, pull up to the side of the body, to avoid injury if it suddenly comes free.

If you come across a large rock, you can either try and prise it out, shatter it, or abandon the hole and start elsewhere. Look at the surrounding ground to see if the rock follows the line of any exposed bedrock. If so, either re-align the fence to avoid it, or if this is not possible, consider using a box strainer. As long as there is 300mm (12″) or more of soil over the bedrock, it should be possible to make a firm structure.

If you decide to try and shatter or cut through the rock, methodically chip away along any visible line of weakness. Don’t use a lot of muscle unless you think you can split it. Take great care when removing large stones or rocks from holes, as they can easily slip and trap the hand. You may have to split the stone if it is too heavy and bulky to grip.

Rock drills

If bedrock is unavoidable, the only practical way of fixing a straining post is to use a rock drill. These can be hired, and are available with a special backpack for carrying to inaccessible sites. They are noisy and tiring to use, and should only be used by an experienced operator. Any work using a rock drill should have preferably been done before volunteers start work. The straining post should be of metal with a pre-fabricated strut, braced onto a rock outcrop or into another drilled hole. Sites with difficult conditions such as frequent rock outcrops may not be suitable for volunteer work, and are best done by fencing contractors with specialist tools and experience.