SWALES at BCIL Townsend
Water
Vegetating a land area means usually 400 plants to an acre. You can save substantially on fresh water costs. .The drive is to provide moisture for root zone and not for watering plants through
. Harvesting rain water from roof tops and land contours.
. Energy free drip irrigation
Storm drains with a difference
. The Sustainable Urban Drainage System is an alternative approach to conventional drainage. We replicate natural drainage, and deal with runoff where it occurs.
. Instead of conventional drains, whose primary function is to carry water away from the site as quickly and efficiently as possible, SUDS carries run-off in swales which are well vegetated, shallow, basin-shaped depressions.
What swales do
• Vegetation in swales slows the speed of overland flow of water, and increases infiltration
• By virtue of its parabolic profile, the carrying capacity of a swale increases exponentially with the depth of water flowing in it, giving it the ability to handle peak storm loads more efficiently
• Vegetation in swales traps suspended solids in run-offs, which get embedded in the soil-bed of the swales • Swales are effective in removing organic and nutrient wastes from the water flowing through them; they are taken up by appropriate vegetation and planting in the bed of the swale
A typical swale
Unlike drains, swales are contoured in contiguity with the surrounding landscape; in dry weather, they are integrated into the surrounding land-use. They are thus aesthetically and functionally more advantageous. Swales are punctuated with periodic detention basins at every road-crossing and intersection. These basins provide dynamic temporary storage, in order to:
• increase the time of concentration of run-off at the exit point
• hold back and slow down the water, promoting local infiltration, and enabling irrigation of local area planting.
• regulate the rate of flow in the swale, reducing peak flows to levels that can be handled by the vegetation in the swale bottom without scouring
Swales carry water better during a rainstorm
This integrated circuit of swales, detention basins, and collection pond, together with some other features like porous paving materials for the roads, and roof run-off harvesting systems, together constitute the Sustainable Urban Drainage System.
The network of swales lead to a Collection pond, or Balancing pond [next to the Tennis Court] which has manifold functions. This is at once a reservoir from which collected run-off can be pumped for re-use to
• balance volume to retain flows from intense rainfall and associated flooding, reducing peak flows further downstream in the regional drainage system
• polish tank for the removal of solids and sediment, as well as nutrients, trace metals, coliforms and organic matter, to a lesser degree The water storage capacity of the Collection Pond is up to 400,000 litres. This water can be used for irrigation of all common areas, as well as irrigation of the home landscapes
Polishing Pond
The water flowing down the swales is given its final stage of treatment, or .polishing., in the terminal collection pond. Here aquatics such as Hydrilla, Saggittaria (Arrowhead plant) and Nymphaea (Water-lily) oxygenate the water thoroughly, improving its composition, as well as clarity and appearance, rendering it suitable for re-use as such. The floating aquatic, Water Hyacinth is also suitable for this purpose; it is, however, highly invasive, and can take over the pond completely to the detriment of all other vegetation.
Harvesting and utilization of run-off and re-cycled waste-water
. The architecture of the TownsEnd campus provides for the harvesting and reuse of roof run-offs. Besides this, however, we also try to use recycled water for all gardening purposes.