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SECTION
6. GLOSSARY
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| berm |
A low, often linear or curvilinear,
mound of soil used to contain or direct runoff water.
|
| biofiltration |
The use of natural systems or biologically-based artificial
systems to remove pollutants from runoff water.
|
| biomimicry |
"Biomimicry is a new science that studies nature's
models and then imitates or takes inspiration from these
designs and processes to solve human problems, e.g.,
a solar cell inspired by a leaf." Janine Bevins,
Biomimicry: Innovations Inspired by Nature (1997) (http://www.biomimicry.net)
|
| bioswale |
A vegetated drainage channel which accepts, absorbs
and treats runoff water, graywater or effluent water,
using natural biological systems and processes.
|
| carbon
sequestration |
The storage of carbon in the tissue of living plants.
|
| cistern |
A holding tank for water, often harvested rainwater.
|
| continuous
trench rootzone enhancement |
A method of providing an adequate root environment for
urban street trees by filling a linear planting pit running
from tree to tree with an engineered soil mix. |
| cut
curbing |
A
variation on conventional concrete curb-and-gutter systems
that penetrates the curb at intervals along its length
to allow some of the runoff water to soak into adjacent
soil rather than draining into a storm drain. |
| decomposed
granite |
The
product of the weathering of granitic parent rock material,
decomposed granite is a granular, compactable soil type
that is commonly used for paths and other paved surfaces.
Decomposed granite ("d.g.") is much more permeable
than conventional paving materials and can usually be
installed at a much lower cost. |
| dragontooth
curbing |
A
variation of cut curbing that alternates short sections
of concrete curbing with short sections of open voids
that allow water to drain into an adjacent planter bed
or other open soil area. |
| dry
streambed |
An
unlined continuous swale running along a natural or artificial
flow line, filled with rounded stones of various sizes
and sometimes with gravel, that slows runoff water and
allows it to percolate into the soil. Dry streambeds are
sometimes equipped with percolation zones concealed beneath
the rocks. |
| ecoroof |
An
engineered system of impermeable membranes, low-density
growing medium and low-maintenance plantings that covers
most or all of the roof of a building. The ecoroof provides
absorption of rainwater, biofilters pollutants, reduces
urban flooding problems, creates oxygen and sequesters
carbon. Various kinds of ecoroofs are used worldwide and
are especially prevalent in Europe. |
| effluent
tax |
A
tax on runoff water which has been directed from private
property onto public property. The tax would help pay
for the costs of managing this water, much as sewer charges
and trash pickup charges are borne by the generator of
the material rather than by society at large. |
| engineered
soil |
Specially
mixed and graded fill soil intended to serve a particular
purpose such as combining structural support for vehicles
with a favorable rootzone for street trees. |
| evapotranspiration
("ET") |
The
combination of evaporation of water from the soil and
transpiration of water through plants. Data on evapotranspiration,
usually measured in inches per day or per week, is used
to monitor and regulate the application of irrigation
water. Evapotranspiration is measured at regional weather
stations (such as those of California’s "CIMIS"
system), and ET data is transmitted to irrigation managers
or directly to automated irrigation controllers, which
then adjust water applications to replace the amount of
water used in the previous measuring period. |
| graywater |
All
previously-used household water except for toilet water,
which is referred to as "blackwater." |
| greenwaste |
Vegetative
material such as lawn clippings, prunings and other plant
tissue. No longer considered waste, greenwaste is used
as feedstock in compost and as mulch. |
| groundwater |
Water
from rain and snow that accumulates underground in the
water table. |
| groundwater
recharge |
The
practice of returning storm and irrigation water to the
groundwater supply by the use of various kinds of infiltration
devices such as ponding areas, percolation beds, etc. |
| impermeable
paving |
Solid
paving materials such as concrete and asphalt which shed
water rather than absorbing it. Impermeable paving contributes
to urban flooding, water pollution and environmental degradation,
and has a damaging effect on the rootzone of adjacent
trees. |
| mulch |
Any loose, non-living material, usually vegetative in
origin, used to cover the soil in a planted area for the
purposes of conserving water, reducing weed growth, improving
absorption of water by the soil, nourishing the soil foodweb,
protecting roots, buffering changes in soil temperature,
reducing surface erosion and providing an attractive,
often walkable, surfacing material. Mulches such as tree
chips, processed greenwaste and ground bark are usually
applied 3-5 inches thick. Inorganic materials such as
crushed rock, gravel or decomposed granite can also be
used as mulch but lack the important biological advantages
of organic mulch. |
| pave-and-pipe |
An
engineering-based system of delivering water directly
into natural waterways via a system of impermeable roads
and other paving and a system of catchments and hard pipes
that daylight into nearby watercourses. Pave-and-pipe
approaches are characterized by an assumption that water
is a waste-product rather than a valuable resource. |
| percolation |
The
slow absorption of water into the soil. Percolation rates
(measured in inches per hour) vary, with sandy soil being
the fastest to absorb water and clay soil the slowest. |
| percolation
bed |
A
widely-spreading subsurface layer or zone of highly pervious
material such as crushed rock that improves the absorption
of water into the soil and facilitates groundwater recharge. |
| percolation
chamber |
An
underground pit of varying dimensions, filled with a highly
pervious material such as crushed rock, which catches
runoff water and allows it to percolate into the soil. |
| permeable
paving |
Any
traffic-bearing surface that also allows water to penetrate
into the subsoil, either through cracks in otherwise impermeable
material or directly through the material itself. Examples
are paving blocks, pervious
concrete, turf block, decomposed granite, crushed
rock, gravel or soil pavement. |
| pervious
concrete |
A
"no-fines" concrete paving material that consists
of 3/8" pea gravel and portland cement, without the
usual addition of sand or other fine material. Placed
over an engineered substrate, pervious
concrete absorbs 100 percent of the water that falls
on its surface. Pervious concrete
technology was developed in Florida and is used extensively
there for public roadways and other paved areas. |
| pervious
pavement |
See
"permeable paving." |
| ponding
zone |
A
low point in the landscape that collects runoff water,
allowing it to percolate into the soil and recharge the
ground water. Differs from a percolation bed or chamber
in that a ponding zone usually consists of native soil
only, without any imported gravel. |
| retention
grading |
Directing
runoff to specific locations on the site, where it can
be treated in bioswales, directed into the soil via ponding
areas or percolation zones, or otherwise held on the site.
This is the opposite of the conventional approach of directing
water off the site as quickly as possible. |
| root-path
trench rootzone enhancement |
A
system of concealed underground trenches leading from
the planting pit of one tree to the planting pit of an
adjacent tree in an urban street tree planting. The trenches
are filled with a loose soil mixture and equipped with
a continuous strip drain. Roots can expand into these
trenches, improving the health of the trees. |
| runoff |
Rainwater,
melted snow or urban water that flows across the surface
of the soil and into watercourses and bodies of water. |
| siltation |
The
deposition of suspended particles of soil by the movement
and action of flowing water. |
| soil
foodweb |
"The
community of organisms living all or part of their lives
in the soil." (Soil Biology Primer, Soil & Water
Conservation Society) The soil foodweb protects the watershed
by decomposing organic compounds and pollutants, storing
nitrogen and other nutrients, and enhancing soil porosity. |
| soil
paving |
The
incorporation of various proprietary additives to natural
soil that results in a semi-solid or solid, traffic-tolerant
surface. |
| stormdrain
inlet |
A
catchbasin, curb drain or other opening at a low point
in a water catchment area that directs runoff water into
a drainage pipe. |
| stormwater
storage chamber |
See
"percolation chamber." |
| structural
soil |
See
"engineered soil." |
| subsurface
filter bed |
See
"percolation bed." |
| swale |
A
low-lying trench or shallow ditch with gently-sloped sides
that directs runoff water from surrounding areas to a
low point in the landscape. |
| Tree
City, U.S.A. |
To
be recognized by the National Arbor Day Foundation as
a Tree City USA, a community must meet four standards:
a tree board or department, a tree care ordinance, a community
forestry program with an annual budget of at least $2
per capita , an Arbor Day observance and proclamation.
The City of Santa Barbara is one of California’s
oldest members of the Tree City USA program. |
| Turf
Block™ |
A
cellular concrete paving block with openings for grass
or other plantings. Other systems use recycled plastic
honeycomb-like panels instead of concrete. |
| water
harvesting |
The
practice of catching and storing rainwater for landscape
irrigation or potable use. |
| waterwall |
A
rectangular, vertical water storage cistern, partially
buried in the soil and partially above ground, used to
catch and hold roof runoff water. The waterwall was developed
as part of the T.R.E.E.S. Program (http://www.treepeople.org/trees)
and a test system has been successfully installed at a
residence in Los Angeles. |
