Site Preparation

A number of environmentally sensitive steps will help to prepare the site, including fencing off sensitive areas, routing site access, siting materials storage, designating haul routes, planning for waste disposal and scheduling utilities.

Cordons sanitaires

Before commencement of construction, it is vital to isolate and fence particularly sensitive areas known as ‘cordons sanitaires’. These include watercourses, ecological hot-spots, archaeological sites and high-quality landscape elements. Commonly, no construction machinery or activities will be permitted within the cordon sanitaire. The type of fencing used must be robust enough to deter entry by heavy equipment or it may be ignored. Although cordons sanitaires should always be shown on plans, on-site refinement by the appropriate specialists — ecologist, archaeologist, landscape architect — is recommended.

Specimen trees are a very common example of a landscape feature to be protected. The entire area of the root system of the tree should be included. Contrary to the popular misconception, the diameter of root spread is roughly two to three times the height of the tree, so protection should be placed well beyond the edge of the canopy. Within this zone, any change in ground levels or chemical spillage may cause permanent damage to the root system and ultimately the death of the tree. Physical damage to tree trunks should also be avoided.

Watercourses and wetland areas can be further protected by allowing a dense growth of vegetation to grow up on the edge prior to the start of work, acting as a buffer to sediment erosion and chemical ingress.

Site access and compound

The establishment of a suitable access point and compound to house temporary offices, storage and toilet facilities will be one of the construction contractor's earliest priorities. The location of the access point and compound should be carefully selected to take account of environmental as well as operational factors.

Because the main access point and compound will be a focus of traffic, materials handling and storage, and waste disposal, it should be sited well away from any watercourses and other sensitive habitats on an area of dry, well-drained ground to minimise the risk of water contamination during refuelling and mixing of materials. A temporary impervious area for handling potentially hazardous materials may be constructed. Use of a single access point is also desirable. In addition to improving safety, it will also restrict the area required to be rehabilitated.

Construction of the hard-standing surface required for access and parking of vehicles and earthmoving plant can often be coordinated with the permanent road layout, so the base courses may be laid as soon as possible and used as a temporary surface.

A designated maintenance area for machinery should also be provided, including an area for wheel-washing to ensure that oils, sediments, and seeds of invasive plants are intercepted. Sediment from the wash-down area should be further intercepted by a silt trap and, if uncontaminated, may be re-used as fill on site.

Materials storage

Closely linked to the establishment and management of the site compound is materials storage. While the aim should be to bring all materials to the site only when required, in practice this may not be possible or economical. Most critical will be fuel and chemical storage. Spillage response strategies should be identified. Diesel, other fuel oil, lubricant and hydraulic fluid may be contained by sandbags and other absorbent materials available on site as part of an emergency spill kit.

Temporary storage at localised working areas, e.g. storage of gravel or sand within the root zone or at green sites, should be discouraged, as it is generally more difficult to prevent contamination. If local storage is unavoidable, topsoil should be stripped from the area to be used before placing the materials.

Haul routes

Done well, the layout of a circulation system of temporary roads allows materials and machinery to move efficiently, minimising both the construction cost and the potential environmental impacts. Topsoil should be stripped from these areas and stockpiled, and ideally the routes should coincide with the layout of permanent roadways. Routes should avoid fairways, wetter areas, and all environmentally sensitive areas, and avoid the potential for run-off to watercourses.

In general, haul routes should be minimized. If possible only allow one-way traffic to reduce slewing of vehicle tyres and tracks and consequent damage to soil structure in wet conditions. Haul routes to green complexes should always lead from the rear of the green, if possible, to avoid compaction of the approach. Temporary haul routes should be decompacted by ripping prior to reinstatement.

Vegetation Clearance

Individual trees or woodland areas should be marked by the contractor and checked by the architect before felling. Specialist forestry contractors, tree surgeons, or others experienced in tree clearance work should always be used. Special care is required to avoid damage to adjacent trees, which may mean taking down individual trees in sections. Staged felling — working outwards from a centreline — allows the greatest control. The landscape architect should be given the opportunity to identify specific individual trees or areas of vegetation that can be successfully incorporated into the design.

Waste disposal

Waste disposal during construction needs to be managed effectively. For example, all waste material should be taken off-site to a licensed facility; empty chemical containers should be disposed of by a licensed agent.

Woodland debris and stumps can be chipped and the material re-used as mulch to suppress weeds in newly planted woodland areas. Felled timber may be sold or repositioned as habitat. Other organic waste can be composted where feasible. Burning should be minimised and only as permitted by local regulations.

Utilities

Scheduling a service provider to identify the location of underground utilities should be addressed from the outset and built into the site preparation timeline. The early and accurate location of services can avoid environmental damage and costly repairs. In expanding utilities, an effort should be made to have all the work done in sequence, to avoid areas being torn up repeatedly.