Bioretention
Bioretention areas that store and treat runoff are filled with a soil
mixture that supports water-tolerant plants. These devices take advantage
of natural processes in soils and plants to remove pollutants from
stormwater runoff through physical filtration, chemical adsorption, and
biological decomposition. The end result is an attractive, landscaped area
that cleans and retains stormwater runoff.

NCDENR Stormwater BMP Manual
For information about bioretention sizing, underdrain design, soil media,
construction and maintenance, visit
NCSU’s Bioretention website.
For information from SC DHEC’s BMP manual, click
here.
Enhanced Grass Swale
Enhanced grassed swales are gently sloping conveyance channels with a
designed underdrain system to filter or infiltrate stormwater runoff as it
flows through the channel. Slopes of less than 2 percent are necessary to
avoid swale erosion. These are best used along roadways and parking areas
in moderate or low density residential or commercial areas.

From
Maryland Stormwater Design Manual (2009)
Click
here for entry in SC DHEC's Stormwater BMP Manual.
Rooftop Runoff Management
Rooftop runoff management includes the use of cisterns or rain barrels and
roof gardens to detain stormwater runoff. Rain barrels and cisterns
collect runoff from roofs and store it for household use, such as garden
watering. A green roof uses vegetation to soak up and evapotranspire
rainfall, much like a bioretention area, before it is discharged. Green
roofs require extra engineering to support the weight of the gardens, but
can be highly effective in removing pollutants.

From
NCDENR Stormwater BMP Manual
NCSU Rainwater Harvesting Modeling Tool
Stormwater Wetlands
Stormwater wetlands are constructed to treat stormwater runoff by
mimicking the physical, chemical, and biological functions of natural
wetlands. Constructed wetlands consist of shallow pools that support
wetland vegetation and wildlife. The natural processes remove pollutants
from runoff before discharging to local streams and waterways.

From
NCDENR Stormwater BMP Manual
For more information about Stormwater Wetlands, visit
NCSU’s Stormwater Wetlands website.
Click
here
for entry from SC DHEC Stormwater BMP manual.
Infiltration Trench
Infiltration trenches are devices that are designed to fill with
stormwater runoff and let it soak into the surrounding soil. These devices
allow the water to be filtered and allow biogeochemical processes in the
soil to treat the water and remove pollutants. They are most effective for
small drainage areas.

From
NCDENR Stormwater BMP Manual
Click
here for entry in SC DHEC's Stormwater BMP Manual.
Pervious Pavement
Pervious pavement differs from conventional concrete or asphalt by using
air spaces to allow infiltration and storage of stormwater runoff.
Conventional pavement generates significant stormwater runoff. Pervious
pavement can often reduce the size needed for stormwater detention
elsewhere on a developed parcel. Pervious pavement is typically used in
low-traffic areas such as parking stalls, emergency lanes, bike paths and
sidewalks.

Horry County Pervious Parking Stalls in Garden City Beach
Technical Resources
For background and research on pervious pavement, visit
NCSU's Biological and Agricultural Engineering pages .
Click
here
for the entry in SC DHEC's Stormwater BMP Manual.
Filter Strip / Level Spreader
Filter strips are vegetated buffers through which diffused stormwater
runoff is filtered. The system includes a forebay to dissipate
concentrated stormwater runoff, a channel with a level spreader to diffuse
the flow, and vegetated buffer or filter strip through which the diffused
runoff flows before it enters a waterway or ditch. The buffer is intended
to remove sediment and pollutants before it reaches the waterway.
Filter strips are vegetated buffers through which diffused stormwater
runoff is filtered. The system includes a forebay to dissipate
concentrated stormwater runoff, a channel with a level spreader to
diffuse the flow, and vegetated buffer or filter strip through which the
diffused runoff flows before it enters a waterway or ditch. The buffer
is intended to remove sediment and pollutants before it reaches the
waterway.

From
Low Impact Development: A Guidebook for North Carolina (2009)
Click
here for entry in SC DHEC's Stormwater BMP Manual.