SUDs look at the control of water run-off @
the point of runoff & filter the discharge
pollutants through a series of measures @
various pts either through the ground then
into the watercourse or sewer
SYSTEMS
INFILTRATION SYSTEMS
Permeable pavements
run-off encouraged to permeate
through a porous pavement
BACKGROUND
load bearing pavours with out-sized joints r
laid over sand & agg bed.
Nr drains & sewers are reduced/ eliminated where run-off is
encourages to permeate through a porous pavement such as
permeable concrete blks/ crushed stone/ porous asphalt
ADVANTAGES
NO add space taken
lead bearing traffic can run over it - good 4 supermarkets
controlled release in 2 sewers/ water course
DISADVANTAGES
easily damaged during construction/ heavy traffic
restricted by water levels
if infiltration not poss an impermeable
membrane can b used with a run off at the lowest
point to keep the pavement free from water in all
conditions
NEW PRODUCTS
land drainage
Land drainage provides an open
conduit 4 water to go to a disposal
point/ area
perforated pipes work by providing an
open conduit for groundwater to follow to a
disposal point, or, a disposal area.
two principles: land drain provides a path of least
resistance for g. water to follow and that left to its own
devices water flows down even in the gentlest of slopes
ADVANTAGES
fast, easy to lay
DISADVANTAGES
clogged with silt
Filter strips and swales
Vegetated surface features that drain water
SWALES are wide narrow channels that r usually
designed as conveyance systems but can also be
designed with check dams to increase attenuation and
infiltration
FILTER STRIPS only attenuate the flow
slightly but they can be used to reduce
the drained impermeable area
ADVANTAGES
remove need for expensive kerbing and roadside drainage
good for anphibians
low maintianance
good for removing polluting solids
DISADVANTAGE
carfeul planning req. 2 ensure the
flow is not too great
maintenace to ensure outlets
are free from debris
soakaways
drain water directly into the ground & r located completely underground
storage of water in an underground chamber and lined with
a porous membrane and filled with course crushed rock.
infiltration trenches are long narrow trenches that
permit water to seep into the chambers
ADVANTAGES
Surface area of soakaway encourages drainage + has capacity to hold run-off
when rainfall rate is greater than the ground absorption rate
easy to integrate into a site - ideal for playing fields etc.
basins can b planted with trees etc improving visual appearance
infiltration trenches provide the opportunity of spreading the water around a site
DISADVANTAGES
clogging
where soil permeability is low & content of soil reducing the water table is high
GEOCELLULAR SYSTEMS
Geocellular Storage system
the system provides volume of storage & also prevents entry of silts etc.
FLOW CONTROLS
Vortex flow control
used to restrict the flow of stormwater down the system
by creating pressure to increase storage volume
OTHERS
green roof system
vegetated surfaces assist in slowing down run-off and moisture control
fuel seperators
protects receiving waters from pollution by oil leakage
COST DRIVERS
The surface area that requires drainage system management
type of surface area, is it soft/hard landscape
Volume & velocity of expected water flow to be dealt with
capacity of the drainage system
space available for the drange system
any geographical features encountered e.g. high water table
likelihood of future maintenance, access room or specialist maintenance.