Scope
This section covers the trades involved in the initial stages of construction including;
- Environmental Protection
- Bulk Earthworks
- Earthworks under residential concrete slab on ground
- Site Drainage
- Root Barrier
Specifications
[+]Potential Problems and Solutions
[+]
Disruption of profiles and corner pegs
Where heavy earthmoving machinery traverses the site, corner pegs will almost certainly be disrupted. To counter this, profiles (and perhaps offset pegs) are erected at some distance from the limits of earthworks. However, sometimes even these profiles are disturbed.
To avoid disruption of profiles ensure that they are placed an adequate distance from the earthworks.
To recover lost profiles always measure from the principal grid line.
Broken services
A common problem is the unearthing of services such as sewer pipes, water pipes, electrical conduits and the like. To avoid this problem, all services should be plotted on the site plan. They should be pegged out and marked with lime before earthworks begin.
Emergency telephone numbers of a plumber and electrician should be prominently displayed in the site office.
Access
Some local authorities require that precautions be taken to avoid tracking clay and dirt from building sites onto public roads. This may be achieved by installing a steel grid that scrapes the soil from the tyres. Ensure that the grids are not too far apart Hosing may assist in some cases. A more economical method is the installation of a 50 to 75 mm crushed rock pad that cleans the tyres. However care is needed to ensure that passenger vehicle access is not disrupted. Ensure that loose rock is contained by a wire cage or by reinforcing fabric.
Design of drainage and on-site detentions systems
When designing a residential drainage system, it is important to understand that each local authority will have its own particular requirements. Some considerations are:
• Ensure that all parts of the catchment are considered, including those that are outside the site boundaries.
• Where required, provide silt traps and sumps to prevent silt and detritus from clogging the authority's trunk drainage system.
• Orifice plates in detention systems are intended to restrict flow. Downstream pipework and outlets should be of sufficient size to ensure that they do not also restrict the discharge.
• It will be necessary to show the plan position and invert level of the outlet to the street gutter or trunk drainage system. The site survey should extend beyond the site boundary to include the footpath and gutter.
• The driveway should be sloped to ensure that it does not channel water into the site. The crossfall should match the street and gutter profile.
• An overland flow path should be provided, enabling run off to bypass the detention tank if it becomes clogged.
