|
Its � 1A��:P��•-r �. �� �� '' `�1I �" ' �� '' �"
<br />Why is stormwater management important?
<br />In nature rainwater filters slowly through soil, removing pollutants. The small
<br />amount of ramwater that does not infiltrate becomes"runoff,"and moves over the
<br />ground at a slow pace, allowing particlesand sediment to settle out. In an urban
<br />environment, non -porous or"impervious"surfaces like streets, sidewalks, parking
<br />lots, and rooftops increase the amount of runoff and prevent water from filtering
<br />through soil. Even a small a mount of wafer quickly runs off these ha rd surfaces,
<br />collecting oil, pesticides, gasoline, and other pollutants as it flows into the storm -
<br />water drains and 'directly out to the San Francisco Bay.
<br />BIOSWALE
<br />In an urban environment, we can introduce nature's method of preventing storm -
<br />water runoff by including a few simple landscape design details. Bioswales are
<br />landscaped slopes and channels designed to move water slowly over plants, so
<br />that sediment and other particulates fiterthrough the soil. This process removes
<br />pollutants and reduces -the amount of water runoff. Bioswales are most effective
<br />when the drainage course is wide with gently sloped sides. Choose plants that
<br />can survive periodic inundation during storms, as well as periods of drought.
<br />Plantsthat are good choices for bioswales include Iris, Ryegrass,Carex, Lupine,and
<br />the Tupelo Tree. Redtwig Dogwood and Sweet Bay trees are also good options.
<br />DRY CREEK
<br />A "dry creek" -a slightly concave or depressed landscaped area and also a type of
<br />bioswale- serves as a, temporary basin during rainstorm s, catching the stormwa-
<br />terand allowing it to slowly filter into the ground. Use attractive stones ofvarying
<br />shapes and sizes to create a dry creek as shown in this demonstration garden. It
<br />doubles as an attractive landscape feature during dry or wet periods.
<br />Y U 6 L 1 Lvr f HYDROLOGIC CYCLE
<br />iM1e Rans(N oW r tlgp.P KiPital On to
<br />PARKING r„dme a•d s Pa. In,, d, ttmage
<br />IT[
<br />and anbrc, d. ntuauybedrtorhemmos
<br />Phed, ie an ongoln9 dwk In tnk ""
<br />Star ffirbd,
<br />"water rs abed Inthe mil . Where
<br />POIIURnband yrtkleiereNeared normally.
<br />r
<br />What can you do to help reduce runoff pollution? r
<br />Simple solutions can be used in your own garden to helpvainwaterfilter through
<br />the soil and reduce pollutants in stormwater runoff-. .
<br />•. Concave (lowered) rather than convex (raised) planting areas r
<br />• Infiltration basins at the end of downspoutssloped away from buildings
<br />• Vegetation planted at the roof drip line, sloped away from buildings
<br />• Pavers on sand bases, in patios and pathways
<br />• Gravel driveways with concrete wheeltracks
<br />PLANT SELECTION
<br />Choosing the right plants can improve the ability of your landscape to filter
<br />stormwater. Deep-rooted plants help keep soil porous and increase water ab- l
<br />sorption into the dirt. Plants with large leaf surfaces collect rainwater before it I ..
<br />lands on the soil, improving the water -retaining capacity of the land. Many plants
<br />are well suited tosurviving periodic heavy rain storms as well as drought, Choose
<br />pest -resistant plants to eliminate the need for chemical treatments. -
<br />r '
<br />FILTRATION SYSTEM
<br />Open filtration basins, such as ponds and swales, are usually landscaped, and the t.
<br />plants themselves maimaiWthe porous soil structure and reduce erosion. Closed r'
<br />filtration basins can be constructed underground. Beneath the bioswale in this ,t
<br />garden, an underground detention device stores an even larger amouro of water,
<br />After the bioswale naturally filters the water, the clean stormwater flows into the t -
<br />detentiondeviceandisslowlyreleasedintothestormdrainsystem. if you don't r
<br />have a lot of space, you can build anunderground closed filtration system, and '
<br />cover it with gravel or crushed stones, leaving the surface area free for parking or I'
<br />other uses. �
<br />i
<br />I,
<br />All.
<br />I
<br />r
<br />�9JJ
<br />asitrrea
<br />,
<br />tn
<br />Ward Polulpn
<br />it
<br />a �
<br />PravenAwr PtoWmn. 'o
<br />- t
<br />I
<br />Y U 6 L 1 Lvr f HYDROLOGIC CYCLE
<br />iM1e Rans(N oW r tlgp.P KiPital On to
<br />PARKING r„dme a•d s Pa. In,, d, ttmage
<br />IT[
<br />and anbrc, d. ntuauybedrtorhemmos
<br />Phed, ie an ongoln9 dwk In tnk ""
<br />Star ffirbd,
<br />"water rs abed Inthe mil . Where
<br />POIIURnband yrtkleiereNeared normally.
<br />r
<br />What can you do to help reduce runoff pollution? r
<br />Simple solutions can be used in your own garden to helpvainwaterfilter through
<br />the soil and reduce pollutants in stormwater runoff-. .
<br />•. Concave (lowered) rather than convex (raised) planting areas r
<br />• Infiltration basins at the end of downspoutssloped away from buildings
<br />• Vegetation planted at the roof drip line, sloped away from buildings
<br />• Pavers on sand bases, in patios and pathways
<br />• Gravel driveways with concrete wheeltracks
<br />PLANT SELECTION
<br />Choosing the right plants can improve the ability of your landscape to filter
<br />stormwater. Deep-rooted plants help keep soil porous and increase water ab- l
<br />sorption into the dirt. Plants with large leaf surfaces collect rainwater before it I ..
<br />lands on the soil, improving the water -retaining capacity of the land. Many plants
<br />are well suited tosurviving periodic heavy rain storms as well as drought, Choose
<br />pest -resistant plants to eliminate the need for chemical treatments. -
<br />r '
<br />FILTRATION SYSTEM
<br />Open filtration basins, such as ponds and swales, are usually landscaped, and the t.
<br />plants themselves maimaiWthe porous soil structure and reduce erosion. Closed r'
<br />filtration basins can be constructed underground. Beneath the bioswale in this ,t
<br />garden, an underground detention device stores an even larger amouro of water,
<br />After the bioswale naturally filters the water, the clean stormwater flows into the t -
<br />detentiondeviceandisslowlyreleasedintothestormdrainsystem. if you don't r
<br />have a lot of space, you can build anunderground closed filtration system, and '
<br />cover it with gravel or crushed stones, leaving the surface area free for parking or I'
<br />other uses. �
<br />i
<br />I,
<br />I
<br />NNW
<br />Ward Polulpn
<br />a �
<br />PravenAwr PtoWmn. 'o
<br />- t
<br />
|