Levelling a Croquet Lawn by Hand
Robin Barry is the convenor of Chiltern U3A croquet group.
A 10m by 12.5m area of the lawn at Chilternwoods (grid 500970, 192270) was levelled by hand between October 2005 and March 2006 to produce a small croquet lawn. The maximum original level difference was 900mm (~36").
To determine the boundary between cut and fill, levels were taken on a 1.25m grid to determine the average level of the area. The best straight line averaging this level was marked across the site and cut with a spade to full turf depth. The boundary was similarly cut and the depth of penetration to stony soil was found to be between 50 and 140mm. A usable 65mm turf depth was decided upon, which meant removing up to 75mm or adding up to 15mm to the turfs.
Starting on this line variable depth turfs were cut two spade widths (380mm) wide by a spade width long and placed, temporally, upside down on the high side immediately adjacent to where they came from (as if they folded uphill on the cut line). This made a trench, which was then doubled in width by cutting another row of turfs and similarly placing them adjacent to the low side, but with a 5mm overhang into the trench.
A 65mm deep wooden box was made (about 400 by 300mm & open top and bottom), which, together with a cut off broom handle (750mm long) was used to revise the turf depth by placing the box on the original lawn and the broom handle on the box and the upturned turf. The excess soil was shaved off the turfs and stored on a nearby concrete base. Some was used to increase the thickness of thinner turfs (the broom handle was propelled by foot pressure over the box while soil was removed or added to the underside of the turfs). The rest was sieved to 5mm down for future use in filling hollows and the stones were mixed in with the stony soil fill.
The stony soil was levelled, using a pickaxe and rake, and compacted by hand ramming to between 60 and 70mm below the average level of the original ground. Marks on the rake handle near eye level were used to sight two separate lines each at the same level (the edges of a very accurately levelled concrete table tennis table with the assistance of a narrow light source at the far end of the table). Tight wires supported on posts are suggested instead.
The turfs were replaced where they came from and patted down. The next two rows of turfs were cut and placed as before. Stony soil from the high trench was transferred to the low trench using the same levelling system and the turfs replaced before they had time to yellow.
As the trenches got further apart a wheel barrow was used to transport the stony soil across the newly placed turfs but varying the route to avoid deep ruts. In addition the lower mark on the rake was progressively moved down to allow for a maximum estimated settlement of 100 mm.
As the depth of cut and fill increased, 200 by 50mm boards were placed on the lower upturned turfs (with a 5mm overlap into the trench) to provide formwork against which the stony soil could be compacted.
One filled corner after six months was 80mm above the lowest area (in cut) and is expected to settle more in time. Some of the sieved soil has been used to fill hollows, 5mm at a time so as not to kill the grass. Generally, the lawn has been mown and rolled once a week. Croquet has been played since mid March 2006 in all weathers except snow. Moss is given no chance to grow! Weeds are removed with an old chisel when seen, and worms are welcome. There are many types of grass but I assume evolution will provide the best in the end.
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