6.5.1. SITE PREPARATION


6.5.1.1. Clearing a 'greenfield' site

For obvious reasons, assessing the scope of works involved in clearing a site of its vegetation is not an exact science, where reliable estimating data can be used. However this simple calculator can be used to establish ball-park manhour and equipment estimates initially, with adjustments being made as more information becomes available, or from experience once work commences.

Suggested 'difficulty' factors are used to differentiate between the easiest and most difficult types of terrain/conditions, together with a basic rate of area clearance per hour for the easiest conditions. This basic rate can be increased/reduced by User if considered necessary, given a real situation, as can numbers of personnel and equipment.

User must input the total area to be cleared, the assessed difficulty factor (1 or greater), hours/days of work, and labour/equipment cost rates. Resulting total estimates will be for one clearance crew and equipment spread doing the work for as long as it takes, with reductions in schedule duration if two or three crews are used simultaneously.

A hypothetical example can be viewed by clicking 'Real time sync', enter secret word 'clearance' and click connect.

6.5.1.2. Removing overburden/topsoil

Following clearance of vegetation from the site area, it is usual to remove the covering layer of topsoil, which is unsuitable for use as a final surface finish for works to follow. This layer can be to a depth of a few centimetres, or perhaps as much as a metre. The extent to which equipment must be mobilised for overburden removal depends on area and depth, for a small site requiring (say) only a JCB, FE Loader, 1 or 2 trucks and a grader. For larger operations, particularly if cut & fill activities are to follow, the use of scrapers is an option. The following calculator can be used to compare the capacities of different scraper models that might be available for use, to calculate the operating cycle requirements and the resultant effects on schedule and cost. The exercise assumes that soil will be removed to a dump on the site's perimeter, from there to be disposed of by trucking off site. (See trucking operations). A hypothetical example can be reviewed by clicking Real time sync at the bottom of this tabulation, enter secret code 'scraping' and click connect.

Note: Allowance for use of a D8 (say) as a 'pusher', plus a grader and compactor, may be necessary.