What are Permanent and Temporary Works at Construction Sites?
Construction site works are generally classified into permanent site works and temporary site works. Permanent site works are required for the entire life span of the structure. For example, some retaining walls can be a permanent structure that is part of the design. However, temporary site works are needed for while to execute certain construction activities for instance a sheet pile wall may be constructed to withstand the soil during construction. This may be considered as temporary retaining wall.
There are several permanent and temporary works that required to be done in construction sites. The list of these construction activities may vary from one project site to another due to many factors such as type of structure and its complexities, topography of the construction site, presence of tree or vegetation, presence of groundwater and ponding.
Examples of temporary site works are site clearing, fill low areas, excavations, compaction of soil, removing existing utilities, install temporary lighting; water; or gas supply, provide temporary drainage to the site, and provide temporary paving. Lastly, retaining walls, roads, parking, ponds and canals, and landscaping are examples of permanent work sites.
Temporary Site Work
Temporary works are the parts of a construction project that are required to enable the permanent works to be built, as per Code of practice for temporary works procedures and the permissible stress design of falsework (BS 5975:2008). Commonly, temporary works are removed after use for instance access scaffolds, props, shoring, excavation support, falsework and formwork.
There are certain situations in which temporary works are incorporated into the permanent works for example haul road foundations and crane or piling platforms may be used for hard standing or road foundations.
The designer or any other individual who arrange the temporary works needs to be aware of the problems that may arise at each stage of the construction process and how to avoid such anticipated issues.
A person with such responsibility needs to coordinate design, selection of equipment, appointment of contractors, supervision of work, checking completion, authorization to load and removal. These works are required to be executed adequately otherwise problems would hinder the construction progression.
1. Site clearing
It involves cutting trees, removal of bushes, and the removal of top soil. Machines such as backhoes, dozers, tree cutting machines, stump splitters, and clearing rakes may be used for site clearing.
2. Demolition of Abandoned Structures
It includes demolishing of abandoned concrete, steel, and masonry structures.
3. Mass Grading
The process of obtaining the required elevation of a ground is termed as mass grading. It is carried out after clearing and demolition of the construction site. Machines like dozers, excavators, and loaders are used for this purpose.
Dozers are good to cut through soil, but it is not a good machine to transport soil. Dozers are efficient when transportation of soil is kept to a minimum. Loader can transport soil in the bucket. Other widely used equipment is the scraper. Scrapers have an underbelly to transport soil and are much more efficient in transporting soil than loaders.
4. Fine Grading
It is conducted after mass grading is completed
5. Compaction of soil
7. Removal of existing utilities
8. Install temporary lighting, water or gas supply
9. Temporary drainage to the site
The construction site would turn muddy due to water after clearing process. As a result, working would become greatly inefficient. This arise the necessity for temporary drainage through backfilling, gravel beds, perforated pipes, and trenches.
10. Provide temporary paving
11. Temporary retaining walls, coffer dams, sheet pile walls
12. Temporary sediment and erosion control structures (rip rap, silt fences)
13. Soil stabilization (vibro-flotation, dynamic compaction, soil surcharging).
It provides safe working environment for construction, repair, inspection, and access.
15. Formwork Installation and Removal
Formworks are placed for keeping concrete at its position till it gain required strength to support self weight.
Permanent Site Work
Permanent works are the parts of a construction project which are used and remain in position for a long time like sixteen years. This includes buildings and structures such as bridges, roads, retaining walls, etc. The construction of most types of permanent works would require the use of some form of temporary works. A list of permanent works in construction sites are presented below:
1. Retaining walls
It is constructed for keeping soil mass at its position either during excavation for foundations or maintaining natural landscapes.
2. Foundation Construction
It might be the first permanent construction activity executed at construction site. It is done after excavation is completed and must be executed with great care in order to have safe foundation structure that bear superstructure loads.
3. Construction of Superstructure Elements and their Connections
It involves all the roads that connect the structure to other facilities and main roads.
4. Parking lots
5. Construct permanent utilities (water supply, electricity, gas, cable, communication)
6. Planting trees
7. Ponds and canals