Modern cities are on the move. The cycle of construction and reconstruction has become perpetual and may accelerate. Vast quantities of earth, rock and building rubble are shifted about. Waste material is excavated to make foundations. Tunnels are dug for transport and infrastructure. Sand and gravel deposits are quarried to make concrete and to obtain fill for embankments. Home improvements lead to skips in every street. Demolition of old buildings yields enormous quantities of rubble. Where should these wastes go? One solution is to place them in the clay, sand, gravel and rock quarries that are excavated when cities are built. Quarries and pits surround modern cities, but filling them has drawbacks. First, quarries are not likely to be near the city centres where most demolition and construction take place. Second, pits tend to be in low-lying land, where there is a danger of polluting groundwater reserves. Third, it seems a wretchedly unimaginative policy.
The eco-city solution is to prepare a landform plan, statutory or non-statutory, showing areas where new hills, valleys, plains and lakes are possible, desirable and undesirable (Figure 8.3). The plan should also mark areas where waste materials can be stored for recycling. Most cities have large areas of land that, for one reason or another, are unused and await redevelopment. They should become temporary stockpiles of sand, gravel, clay, rock, demolition rubble, metal, timber, topsoil, garden waste and other materials, equivalent to the area behind your garden shed. At the town scale, areas for new hills, lakes and valleys should be marked. Often, they will be on the urban fringe, where the city is expanding. Such land can be made into wondrous new landscapes. All we need is imagination, and plans. Demolition material should not be removed from building sites unless it can be shown that it will be put to good use elsewhere. This principle should be written into urban landscape plans.
Fig 8.3 Urban landform plans should show where change is (1) possible (2) desirable (3) undesirable