Levelling is of particular importance for the construction of patios and lawns. Assess the area to be levelled carefully in order to minimise the amount of soil to be moved during levelling. If a garden has considerable variations in level it may be more realistic to work with the contours, constructing walls, terraces, sunken gardens and or water features. There are many instances where it may be necessary to level your garden.
Choose your level; one which will not entail too much removal or addition of soil, and knock in a master marker peg. Using a level board, (a straight plank approximately 2m long and 2cm thick,) knock in other pegs level with the master peg, by placing the level board on the master peg and the new peg and aligning with a spirit-level on top of the level board. Work across the site carefully tapping in level pegs, and avoiding tripping over them! Soil can then be removed or added until appropriate level achieved.
For very uneven ground, use of 'boning rods', ('T'-shaped markers approx 1m tall with a cross-piece of 45cm.) These are usually used in threes, in conjunction with marker pegs. Site the first master peg on the highest part of the plot. Site the next peg 0.5m away, checking the level with level board and spirit-level. Place one boning rod upright on the first marker peg, and the second boning rod on the second marker peg. 'Sight' across the 'T' pieces of these two to a further boning rod in the distance, and knock in a marker peg to the correct level. This method is useful in that it can work over undulating ground, plants and rubble to give a useful first levelling. Subsequent levelling should proceed using a level board and spirit-level.
Another way to quickly (!) find out the difference of level in two points, entails 2 people - the kids will love it - a length of hose-pipe, a funnel and some water.
Method... The person with the end of the hose that has the funnel in it, stands at the highest point of the area to be assessed. The height of the funnel from the ground is noted, and should remain constant. (It may be a good idea to fasten the hose/funnel on to a stake driven into the ground.) The other end of the hose is taken to various positions where you require to know the difference in levels. Water is poured into the hose - slowly via the funnel. The 'free' end of the hose is raised until water no longer seeps out. Measure how high off the ground the hose needs to be to reach this state of equilibrium, and deduct the height of the funnel (top) from the ground. This is the difference in levels.
Example.. If the top of the funnel is 60cm off the ground, and the hose full of water has to be raised 125cm from the lower ground level, then 125cm minus 60cm gives you the answer of 65cm. This is the difference between the ground level at point 'a' - where the funnel is and point 'b' where the other end is. To get point 'b' to the same level as point 'a', it will require to be 'built up' by 65cm. For absolute accuracy, you must ensure that the funnel end is full to the rim.
This system is particularly good for sorting out levels over fair distances - providing the hose is long enough.
Never, Never, assume that a plot is level, "because it looks it". Take the steps above to ensure that you have a good level garden, patio or lawn.
Where soil levels require altering it is preferable to remove the topsoil and save it for later use, rather than to bury it and end up with poorer soil on top. If hollows are to be filled in with soil, consolidate (tread down) regularly to prevent subsequent sinking.