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Planning and Managing for Pollution Prevention
hen planning a new operation or
expanding an existing one, you as a
nursery manager must choose a site
carefully to avoid environmental
risks and design the total drainage
system properly. For example,
locating your nursery within a
quarter mile of a stream or lake is
rarely a good choice if you want to prevent water
pollution economically because close proximity to
a waterbody increases the chances that nursery
runoff will discharge directly to a stream or lake.
Designing a drainage system for growing beds,
lath houses, and propagating facilities or
greenhouses so that no untreated drainage leaves
the property will save you thousands of dollars
over redesigning and retrofitting an existing
system for pollution control.
If you have an established nursery, you
probably do not have the luxury of starting over to
minimize the potential for environmental harm.
Instead, you can prevent and control pollution by
retrofitting your operation and changing
management practices. Some effective BMPs you
should consider:
• Add a field border around your operation
with permanent upright grass to slow
velocity and rapidly growing trees to
remove nutrients from runoff. (Research has
shown that poplars have some of the highest
nutrient uptake rates.)
• Establish vegetation on the upslope edge of
the property to slow outside water from
flowing across your operation.
• Evaluate your fertilization schedules and
methods. Use soil and tissue testing to
ensure optimum — but not excessive —
growth. Consider changing to a more precise
application method, such as microfertigation
(injecting fertilizers through the irrigation
system) or mechanical incorporation.
Evaluate the fertilizer in use: is a form
available that is less environmentally mobile,
such as a slow release formula? Install a
backflow preventer if fertigation is used.
Evaluate the growing habits and
requirements of different plant materials and
species. Match pesticide and fertilizer
amounts to each plant's specific need so
species that need less receive less.
Rearrange your stock on growing beds so
varieties that need the most fertilization and
irrigation are located farthest from a
waterbody or a drainage channel that
discharges near or into a waterbody.
Develop and implement an integrated pest
management (IPM) program that uses pest
scouting to identify and treat infestations
before they become severe. Select the least
mobile and persistent chemical. Explore the
use of biological controls.
I Use a soil or growing medium that holds
water better than your nursery's present mix
(but still provides sufficient aeration and
drainage) to decrease irrigation frequency
and amount.
Assess your irrigation methods and
schedules. Avoid methods that use
large-volume overhead sprinklers (almost
two-thirds of this water runs off carrying
excess fertilizers, pesticides, and other
pollutants). Try precision application with
drip irrigation. Maximize the efficiency of
existing systems by irrigating when wind
velocities are lowest.
I Select varieties for production that require
the least intensive growing methods. Native
plants often require much less fertilizer and
water and are much less prone to disease
and pest damage than introduced varieties.
Aggressively market these environmentally
friendly plants.
I Practice source reduction in your weed
control program by mowing the perimeter of
your nursery to prevent weeds from going
to seed; similarly, establish a regular (daily)
hand weeding schedule for the same reason.
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Turkey Creek uses several high efficiency filters
(ranging from 20 to 80 microns) in its water
treatment system to remove solids; the water
intake pipe is also screened. Both the water intake
and filters use a back-pressure system to eliminate
clogging. To prevent algae accumulation, 3 ppm of
chlorine is added to the water as it enters the
treatment system.
After mechanical filtration, the water is treated
in a carbon tank filter system to remove herbicide
and pesticide residues — an important step toward
protecting plant and water quality. These residues
can become increasingly concentrated as irrigation
return water or rainfall runoff water is reused
again and again.
The final treatment involves an ultraviolet light
system that destroys fungi, bacteria, and any other
waterborne spores. This step prevents the spread
of disease to nursery stock and the discharge of
bacteria-laden water from the nursery. The
treatment system water and any discharge water
(if the system is bypassed in an unusually intense
storm) is tested at an approved lab for pH, nitrate,
nitrite, total phosphorus, fecal coliform, and
certain metals.
Turkey Creek has to contend with some unique
problems that could be avoided in a newer
nursery. For example, it must manage a
channelized highway runoff drain (off-site water)
that flows across the property. The site has little
natural drainage and much of the irrigation return
water must be pumped into detention ponds and
through the rest of the system (including treatment
and re-irrigation) because little gravity flow is
available. All blocks, now properly crowned and
graded to drain to the concrete ditches, originally
had to be stabilized (as did the roads) because the
site is located on high shrink-swell clay soil.
Turkey Creek recommends that nurseries
planning to install a pollution control system plan
in advance (especially in site selection) and devote
the needed time, effort, and expense to design and
build the most effective pollution control system
possible — one that can be expanded as the
nursery grows.
Case Study: Nines Nursery
ith almost 250 employees,
Hines Nursery (also
located near Houston) is
one of the largest
containerized wholesale
growers in Texas. Hines'
recycle/reuse system
includes retention of
irrigation return flows
and the first half inch of rainfall,
water filtration and reuse, and
various management methods that
maximize production while
minimizing input.
Hines has a system of gates,
pump stations, concrete channels,
and ditches to carry (using gravity
flow) irrigation return water to two
holding ponds. After filtration, the
water is recycled back through the
irrigation system, which consists
mostly of overhead sprinklers.
Before Hines installed its
recycle/reuse system, an estimated
70 to 80 percent of the irrigation
water was discharged and lost.
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Sand filters for water treatment at Hines Nursery near Houston, Texas.
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Case Study: Turkey Creek Farms
urkey Creek Farms, a wholesale
nursery north of Houston, Texas, uses a
combination of structural and
management BMFs to prevent and
control runoff, irrigation discharge, and
associated pollution.
Turkey Creek uses an almost totally
closed irrigation recycle/reuse system
to manage the more than one million gallons of
water per day needed for its 120-acre facility. The
system includes concrete-lined irrigation return
and rainfall runoff collection ditches that drain to
two clay-lined detention ponds. Water is pumped
from these ponds to a central holding basin and
then goes through a treatment process that
removes solids, organics, pesticides, and bacteria.
The treated water is discharged into a large,
high-density, polyethylene-lined holding tank.
From here, the treated water is either used for
irrigation or pumped to the nursery's original
water supply pond where it is mixed with well
water.
This system will cost Turkey Creek about
$400,000 when fully completed. Maintenance costs
(including replacement of treatment system
components) are expected to be about $30,000
annually — a considerable investment in a short
time. However, the nursery, which previously used
four 6" wells almost continuously, lowered its
pumping costs considerably
by installing the water
recycle/reuse system and
expects a significant cost
savings over the next few
years. Turkey Creek
recommends that you install
retention ponds first and
follow up with a water
treatment system within a
year.
Management BMPs,
usually the least expensive
part of the system, can often
be modified right away. The
nursery uses a mixture of
preventive or good
housekeeping procedures
(e.g., proper disposal of
clippings and silt fences
around bark storage and Retention pond for irrigation return flow and runoff at Turkey Creek Farms
near Houston, Texas.
potting-up areas) to keep organic materials out of
irrigation and runoff return water. This practice
also decreases treatment costs and prevents plant
damage from mold and fungus. Most plants are
fertilized with a controlled-release fertilizer to save
time (the slow-release formulas are designed to last
10 to 12 months without re-application), decrease
fertilizer cost (less fertilizer is lost through
leaching), and keep excess nutrients out of the
discharge water.
As part of its integrated pest management
program, Turkey Creek uses the least residual
pesticide and is experimenting with a preventative
pest control program that incorporates
pesticide-free oils to coat and smother insect pests.
The key to this program appears to be a regular
spray schedule that is coordinated with the insect's
growth/rep reductive cycle.
Drip irrigation is now used on about one-third
of the plants grown at Turkey Creek; overhead
sprinklers are still used on the remainder. The
nursery is evaluating the sprinklers' water use
requirements and converting to the drip system as
expenses allow. To conserve space and use the drip
system optimally, the nursery has interspaced
deciduous trees on racks with smaller,
low-growing evergreens. Successful use of a drip
or trickle irrigation system depends on clean water
because the tiny emitters clog easily.
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Structural BMPs
ow can a nursery keep all runoff or
irrigation return water on its property?
Detention ponds, tailwater pits, and
catchment basins — coupled with
water recycling — can help your
nursery get close to that goal. Although
these systems include an initial design,
engineering, and construe hon cost, they
often create a significant cost savings because less
water is pumped. While researchers cannot fully
predict environmental cost savings from using
these detention ponds and water reuse systems,
they have found that proper design, installation
(lined to prevent groundwater contamination),
and management can reduce nutrient discharge
concentrations up to 80 percent.
Success does not depend as much on the
detention pond (normally about 20 percent
effective in removing nutrients) as the
recycle/reuse system that diminishes discharge.
Since they act like settling basins by allowing the
heavier particles to drop out, detention ponds
effectively remove suspended solids and any
pollutants that are adsorbed to sediment particles.
However, using a pond alone is not a particularly
effective method to remove dissolved pollutants,
especially pesticides and some forms of nitrogen.
Reusing your irrigation water can cause
problems with salinity, nutrient, algae, and bacteria
buildup. Recycled/reused irrigation water may
need treatment to protect nursery stock from
waterborne diseases and frequent testing so the
nutrient concentration can be factored into your
fertilization program. Testing will help you avoid
over-fertilization (and its associated scorch or
weedy growth) or nuisance algae growth in ponds.
Investing in a simple testing lab safeguards your
nursery's investment in container stock.
Growing Beds
Reuse
Discharge
Treated Water
Pond
Filter System
and Water Treatment
Flocculation
Pond
Diagram of irrigation water management and reuse system for containerized nurseries.
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Situated in an area with an average rainfall of
50 to 60 inches annually, the nursery contains 200
acres of graveled growing beds on both sides of a
creek. Because of the average high rainfall, Hines
was concerned about the large water volume its
system would have to accommodate, so the
nursery installed several new drainage channels to
divert the flow from direct discharge into the creek.
The low maintenance system cost Hines about
$800,000; upkeep on the water recycling system is
estimated to be $25,000 per year. The nursery
expects to save substantially on annual costs
because of lower pumping expenses.
One of only a few nurseries in Texas with an
individual state discharge permit issued by the
Texas Water Commission (Turkey Creek is
another), Hines collects water samples and sends
them to an independent laboratory for analysis.
Hines uses data from these analyses to improve
production and decrease expenses by modifying
their fertility management program. The nursery
uses both fertigation and controlled-release
fertilizers to grow their products.
Hines personnel believe the recycle/reuse
system has made them better managers. Although
Hines spent a considerable amount of money over
the past four years to research, design, engineer,
and install its system, the nursery has maintained a
profitable business.
V
TERRENE
INSTITUTE
For additmml iw/ffrmation, contact Susan Alexander, The Terrene Institute, Route I, Box 262, Pimland? TX
75968 (%AjS7-4821), This project was funded by the U.S. Environmental Protection Agency, Region
^mget^t&^rision, Water Quality Management Branch. Prepared by Susan V, Alexander, JT&A,
Qlem Ass^^^in cooperation with the Texas Association of Nurserymen. For copies of this publication and
others l» Jlfipas, contact The Terrene Institute, 1700 K Street, NW, Suite 1005, Washington, DC 20006 (202)
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Printed on Recycled Paper
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