... a major cost in any development involving earthworks is the transportation of construction materials
Grading of the grit drainage layer
the contractors, White Horse, on their toes, but thankfully we are all extremely proud of the finished product.”
. November 2006 -IInstallation of the forced slit drainage system prior to seeding
Mid January 2007 -S following two months of intense rainfall Surface in poor condition
SO, what do natural turf pitch consultants do when brought in on such a project? The first step in the design process was the implementation of a detailed three-dimensional topographic survey. In parallel to this a full survey of the site was performed, which included an assessment of the existing geology, topsoil and underground services. “We are often instructed to help with liaison with the powers that be in the early stages of many of our projects. Gerald Leeke had already established a good relationship with the local council and, in spring 2006, he asked us to prepare the detailed Planning Consent design drawings. These included three-dimensional computer generated ground models, plus sections of the existing and proposed ground profiles. A few minor issues and concerns were soon resolved, and so permission was granted to commence construction of the high quality training pitches with a state of the art, fully automatic, irrigation system. Soon afterwards, the design was issued for competitive tender to a select list of proven specialist natural turf pitch contractors. Following the tender evaluation process the contract was awarded to White Horse Contractors Ltd of Abingdon.
Late April 2007 -t
is now making a difference to sward density and rooting depth
the good weather
As most of you may be aware, a major cost in any development involving earthworks is the transportation of construction materials including soils, sands and drainage aggregates, to the site. Paying a high price to bring in material, which is then left over and needs to be moved at further cost is an unacceptable expense. It also makes the effective use of existing on site materials very important. To optimise the use of existing materials and to minimise the purchase of new ones, we make use of the latest three dimensional ground modeling software, in conjunction with the detailed topographic survey, to compute the exact quantities of construction materials required. The software also produces a detailed output on where subsoil needs to be cut from and where it
Spring 2007 -IIrrigation in full swing
should be used as in-fill. All major earth moving was performed using large back-acting excavators and bulldozers fitted with compaction equipment. However, armed with the computer 3D model, the finer cutting and filling, to produce a precisely graded plateau for construction, was achieved using a laser controlled grader. Firstly a rotating laser is set up to the required gradient and level, and then a grader moves across the site using the laser as its datum point. Where material needs to be removed the laser controlled blade planes off a layer which is then deposited where levels are low. The final result is an accurately laser graded cut and filled formation. In this case we incorporated a 1 in 100 gradient across the area to aid drainage, but kept the line of play level. The natural drainage on the site was poor and the near surface geology was comprised of glacial till which was a mixture of clay, gravel and pockets of running sand. The problems presented by the variable and, in places, wet ground conditions were exacerbated by the fact that the land was traversed with deep Victorian land drains installed at 6.0m centres. In addition, following the earthworks, there remained a long and steep slope running down from a road to the upper edge of the training area. While the training teams favour this, as they sprint up the slope to develop strength, in the wet, it directs a considerable volume of surface water runoff over the site. To address these problems a deep trench was dug at the base of the slope and a 300mm diameter perforated drainage pipe laid. This primary drain would act as a cut off drain to protect the work in progress and, later, the finished product. Following the installation of the cut off drain and the laser grading of the formation 150mm diameter carrier drains were installed around the perimeter of the area. From these drains 300mm deep lateral drains were cut to into the formation at 5.0m centres. These were then in-filled with approved 5mm-10mm drainage aggregate. A separator geotextile was then placed between the drains and 150mm depth of grit was installed to form a drainage carpet across
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