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BACKGROUND
Incline Village, Nevada, uses a
constructed wetland for disposal
of secondary effluent. Starting with
an existing, mineralized, warm-water
wetland near Minden, Nevada, the
Incline Village General Improvement
District developed a system which uses
natural processes both to renovate
wastewater and benefit wildlife. With
this system, Incline Village can meet
several goals to protect the environment:
• dispose of treated effluent effectively
and economically
* expand the existing wetland habitat
for wildlife
• provide an educational experience
for visitors
Until 1975, effluent treated at the
Incline Village General Improvement
District's 3.0-mgd activated sludge plant
was exported from the Lake Tahoe
Basin and discharged into the Carson
River during the winter and used for irri-
gation of hay fields during the summer.
A discharge permit issued in 1975
required either more stringent treat-
ment standards or a year-round, land-
based disposal system. In 1979, a facility
plan funded by the U.S. Environmental
Protection Agency (EPA) and prepared
by CH2M HILL recommended meeting
a zero surface discharge standard by
using land application during the grow-
ing season and constructed wetland
enhancement during the remainder of
the year. Local agency reviews and
public hearings were held, and the
wetland concept was finally approved
in 1982. The project was designed by
the environmental engineering firm,
Gulp »Wesner «Culp, with technical
assistance from Dr. Robert Kadlec of the
Wetlands Research Group. The design
was completed in 1983 and construction
was finished in November 1984.
The Incline Village Wetlands
Enhancement Facility is
located south of Carson City,
Nevada, about 10 miles east
of Lake Tahoe.
^Village
Wetlands
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SITE DESCRIPTION
20-mile pipeline carries the
treated effluent from the treat-
t plant to the Wetlands
Enhancement Facility. Constructed
wetland cells, berms, a flood dike, and a
distribution ditch are the main compo-
nents of the system. The 770-acre site
is made up of several distinct areas:
• constructed wetlands
• natural warm-water wetlands
• seasonal storage/waterfowl areas
• effluent storage area
• upland area
Eight constructed wetland cells are
the primary disposal
area for the treated
effluent. There is no
surface discharge from
the wetland disposal
area because of
evaporative water
losses. Each cell has a
deep channel down its
center that discourages
growth of emergent
vegetation and
furnishes a landing
area for waterfowl.
Islands within this
channel serve as
nesting sites.
The natural warm-
water wetland provides
a natural habitat for
plants and animals and
is not part of the
disposal process.
The seasonal storage/waterfowl
areas store excess water during periods
of low evaporation and high rainfall.
They are dry during summer and fall,
except for a small ponded area fed by
warm-water springs. Three islands in
this area provide nesting habitat for
waterfowl. Each of the islands was
planted to provide food, screened
areas, and trees for birds.
The 2.8-million-gallon effluent
storage area is used only during high
flows or heavy rainfall. The 200-acre
upland area is used to dispose of
effluent by spray irrigation during
extended rainy weather.
A resident population of
Canada geese use the berms
and islands for nesting.
Wetland treatment cells with
islands were constructed
around the existing warm-
water wetlands.
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OPERATIONS AND MANAGEMENT
The treated effluent passes through
the 390-acre system of wetland
cells and is disposed of through
evaporation, transpiration (evaporation
through plants), and percolation (seep-
age through soil). The system works in
harmony with the existing warm-water
wetlands, adapts well to year-round fluc-
tuations in weather and temperature,
and meets state and EPA water-quality
requirements while avoiding surface
discharge to the Carson River.
Effluent flows from Cell 1 through
Cells 2,3, and 4 before overflowing to
the distribution ditch. Overflows from
Cells 3 and 4 are diverted to Cell 5 for
storage and evaporation. Water that
must be stored is held in Cells 6,7, and 8.
Using weather instrumentation and
monitoring equipment, plant operators
determine rainfall, evapotranspiration
and percolation rates, and groundwater
quality. These data are used to estimate
the evaporation rates at the site and to
Site Boundary
determine compliance with groundwater
quality standards.
The size of the constructed wetland
needed for evapotranspiration and
percolation of effluent was determined
by calculating several water balances
for the site. Evaporation rates were
estimated with the Penman method
and were based on limited data available
for the area. Subtracting the evapo-
transpiration and percolation from the
rainfall yielded the net water loss from
the site. Dividing the net water loss into
the effluent volume gave an estimate
of the required acreage.
Percolation is critical to successful
operation of the project. At least
1.1 inches of percolation per month
is required at the projected flow rate.
If percolation occurs at this rate, only
175 acres are needed to treat the efflu-
ent. If percolation does not occur, as
much as 450 acres would be required.
The Incline Village Wetlands
Enhancement Facility includes
a total of 770 acres of wetlands
and uplands.
Operations, Building
Saratoga
Hot Springs
Effluent
Pipeline
Irrigation Pipe
Access Road
Seasonal Storage
Waterfowl Area
Natural Warm
Water
ands
Observation Trail
Weather
Station
Site
Distribution,
Ditch' L Cell 4;
14" Effluent
Pipeline _J Warm Water
Extension 1 Outlet Sewer
14" Effluent
/ Pipeline
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PERFORMANCE
3000 -/
| ecause there is zero discharge
surface waters from the
"incline Village Wetlands
Enhancement Facility, no surface water
quality criteria must be met. However,
many parameters of regulatory interest
are monitored in the wetland cells.
Even though all surface water evapo-
rates or is lost to percolation, water.
quality improvements can be observed
as the water passes through the cells
in a serial pattern.
For seven years, nitrogen and phos-
phorus levels have been reduced in the
water, even during the winter. Nutrients
in the last cells display only 2 to 3
percent of the concentration values in
the incoming wastewater effluent.
The effect of evaporation can be seen
in the increases of total dissolved solids
(TDS) and chloride ion as water moves
through the cells. The evaporites in the
original desert soils are rearranged by
water movement, with increases in
concentrations in the downstream cells.
However, there is no evidence of a
continuing buildup of these ions in
the downstream cells. Apparently,
transport of solutes from upstream
to downstream cells has reached a
balance with other processes.
CelM
Cell 2
Cell 3
Cell 4 Cell 5* ~Cef| 6 ' Cell 7 ' Cell 8
* Average of Cells 5A and SB
The concentration effect of evaporation can be seen in the increase of total
dissolved solids as water moves through the cells.
5-f
CelM
Cell 2
CelI3
Cell 4
Cells* Cell6 Cell 7 Cells
* Average of Cells 5A and 5B
The concentration of ammonium nitrogen is reduced as the water flows
through the cells.
Wetlands Design Criteria
Flow, Average Annual 1.66 mgd
Flow, Maximum Daily .2.68 mgd
Influent Quality
Suspended Solids 20 mg/l
BODs i, 20 mg/l
TDS ;..... 240 mg/l
Total Phosphorus as P 6.5 mg/l
Total Nitrogen as N 25 mg/l
Constructed Wetland Area
Cell 1 „,; ...37.9 acres
Cell 2 ..4.........V.. .........33.2 acres
Cell 3 ;. 27.3 acres
Cell 4 ; 23.4 acres
Cell 5 (overflow area) 117.3 acres
Cells 6 & 7 (floodp'lain area) 105.6 acres
Cell 8 (seasonal storage) 42.5 acres
Wetland Depth
Emergent Marsh ..... 0.5 feet
Open Water 2.0-3.0 feet
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ANCIILARY BENEFITS
Plant Communities
Wildlife Habitat
Vegetation is essential to the
success of the wetland. Plants
increase evapotranspiration by
as much as 20 percent in the summer
and improve water quality. Wetland
vegetation includes rush meadow, three-
square bulrush, tule cattail, and willow
thickets. Upland vegetation consists
primarily of sagebrush, rabbitbrush,
greasewood, and salt grass, which
tolerate the alkaline soils. Floodplain
vegetation includes rabbitbrush and salt
grass, plants which can exist in saline,
silly loam, and clay soils.
Project implementation has allowed
existing plant species to flourish.
Careful planting of hundreds of trees
and bushes added a new component to
the ecosystem, with taller vegetation
providing new perching and nesting
areas for hawks and eagles.
The wetlands provide three types
of wildlife habitat: permanent
wetlands, seasonal wetlands,
and uplands.
Many types of aquatic and nonaquatic
wildlife coexist at the site. Aquatic
invertebrates such as insects, worms,
snails, and crayfish eat algae and other
plants and serve as food for larger
organisms. Fish such as largemouth bass,
black bullhead, green sunfish, mosquito
fish, and carp were identified before
construction and were transferred to
several areas within the site.
Birds occupying the site include
ducks and geese, shore birds, raptors
(hawks and eagles), and passerine
(such as blackbirds). Many migratory
species travel through the Carson
Valley and nest on the islands in the
seasonal storage/waterfowl area or
the grassy areas along the edges of the
cells. Animals common to the area
include deer, coyote, skunk, mink,
muskrat, rabbit, squirrel, chipmunk,
and the western yellow-bellied racer.
The natural warm-water
wetlands provide a year-round
habitat when the constructed
wetland cells are dry.
The yellow-headed blackbird
prefers nesting in the emergent
marsh areas.
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Recreational Uses
n observation area is provided
at the operations building in the
theast corner of the site to
encourage the public to enjoy and learn
about man's use of his natural environ-
ment. Observation trails traverse the
warm-water wetlands and created
wetlands so that visitors may experience
the diverse wildlife and vegetation at the
site and see how the project operates.
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Migratory trumpeter swans find winter habitat at the wetlands enhancement facility.
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ACKNOWLEDGEMENTS
Incline Village General Improvement District
Elected Trustees
Robert Wolf, Chairman
Pamela T. Wright, Vice-Chairman
Roberta Gang, Secretary
Jane Maxfield, Trustee
Greg McKay, Trustee
Professional Staff
Robert A. Hunt, General Manager
John R Shefchik, District Engineer
Don N. Richey,
Sr., Operations Superintendent
Grant Funding
U.S. Environmental Protection Agency,
Region 9
Nevada Division of
Environmental Protection,
Construction Grant Section
Design Team
CH2M HILL
Facilities Plan and Conceptual Design
Robert Chapman, Project Engineer
Richard Mishaga,
Environmental Scientist
Gulp »Wesner«Culp, Design
Wetlands Ecosystem Research Group,
Wetlands Consultation
Robert Kadlec, Senior Consultant
This brochure was prepared by
CH2M HILL for the
U.S. Environmental Protection Agency.
Project Cost
Description
Amount
Engineering/Inspection... $ 623,493
Land $772,503
Construction $ 3,568,000
Total Project $4,963,996
Innovative/Alternative grants funded
85 percent of the project.
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