SPRAY & DRIP IRRIGATION Winter 1999

Pipeline
Vol. 10, No. 1
SMALL
AL
N

FL
O
N AT I

OWS
CL

E
E

S
AR U
INGHO

Small Community Wastewater Issues Explained to the Public

SPRAY AND DRIP IRRIGATION FOR WASTEWATER REUSE, DISPOSAL

id you ever wonder how golf Another benefit of applying wastewater

D courses keep their large fair-

ways looking so lush, healthy,
and green all season long?
The answer may surprise you.
to land is that the soil provides additional
treatment through naturally occuring
physical, biological, and chemical pro-
cesses. Irrigating with wastewater also
Treated wastewater can
be reused to irrigate . . .

In many communities in the U.S. and adds nutrients and minerals to soil that are • lawns;
around the world, treated wastewater is good for plants, and it helps to recharge • parks;
reused to irrigate golf courses, lawns, valuable groundwater resources.
• landscaped areas around offices
landscaping, forests, and even crops.
Because water is such a precious com- A Solution for “Problem” Sites and industrial developments;

modity, recycling wastewater can have Irrigation systems often can be used in • landscaped areas around
both economic and environmental benefits place of soil absorption fields (drainfields) residences;
for communities. Irrigation also can be to provide final treatment and disposal of • pasture grass;
the most practical and environmentally- wastewater from individual onsite sys- • highway medians;
friendly way communities can dispose of tems, such as septic systems and home
• golf courses;
treated effluent from wastewater treatment aerobic treatment units. As the demand
plants and individual home systems. for land in rural areas is increasing, more • cemeteries;
sites are being developed in places previ- • forests;
Better for the Environment ously considered unsuitable for onsite
• trees, corn, alfalfa, and other
Currently, the most common way com- systems. Irrigation sometimes is permitted
feed, fodder, and fiber crops; and
munity treatment plants dispose of waste- as an alternative wastewater disposal
water after treatment is to discharge it to method for difficult sites, such as areas • food crops.
surface waters. However, as populations with slowly permeable soils, shallow
grow, the burden to local streams and soils, or complex topographies.
rivers is increasing. Reusing wastewater This Pipeline issue provides a brief
to irrigate land can help protect precious overview of two types of wastewater irri-
when they may be a good option for
surface water resources by preventing pol- gation systems—spray systems and sub-
homes, businesses, and communities.
lution and by conserving potable water for surface drip systems—how they work,
Operation and maintenance issues also
other uses. their advantages and disadvantages, and
are discussed.
Readers are encouraged to reprint
Pipeline articles in local newspapers or
include them in flyers, newsletters, or
educational presentations. Please include
the name and phone number of the
National Small Flows Clearinghouse
(NSFC) on the reprinted information and
send us a copy for our files.
If you have any questions about reprint-
ing articles or about any of the topics dis-
cussed in this newsletter, please contact
the NSFC at (800) 624-8301 or (304)
293-4191.
 SPRAY & DRIP IRRIGATION

Is irrigating with wastewater a good option

for your home or community?
If you live in an area where water must is higher quality than the wastewater system clogging. Additional treatment
be conserved or is expensive, or where discharged from treatment plants due to may be necessary to protect the receiving
other options for disposing of wastewater the additional treatment provided in the soil. environment and may include secondary
are restricted, then reusing wastewater for Regulations protect public health and treatment plus disinfection. This adds to
irrigation may be a good option for your the environment by requiring that waste- the cost of building, operating, and main-
home, farm, business, or community. It also water always be pretreated prior to irrigation taining systems, which should be consid-
can be a good choice simply because it is and by restricting its quality, use, and the ered when determining whether irrigation
an efficient use of local resources. manner and location of its application. is a practical wastewater disposal option.
In arid climates, such as in Arizona, New Cumulative levels of nutrients, salts, heavy
Mexico, and parts of California, for exam- metals, and disease-causing organisms also Site Conditions Are Important
ple, or where the demand for water threat- must be monitored in the soil at some sites. Not all sites are appropriate for waste-
ens to exceed the supply, as it does in parts water application. Communities wishing
of Florida, many homes and businesses Regulations Vary to dispose of wastewater from treatment
could not afford to maintain grass lawns Wastewater reuse is not permitted every- plants through irrigation sometimes must
or landscaped areas without reusing waste- where. Regulations vary from state to state purchase or lease suitable land for dispos-
water. In Hawaii, treated wastewater is used and sometimes from community to commu- al or enter into cooperative arrangements
to irrigate pineapples and sugar cane to nity. State and local governments may have with local farmers or landowners. Sites
save money and conserve fresh water for additional or more stringent requirements near surface water or high groundwater
other uses. than the federal regulations. often are restricted, especially when
Irrigation also can serve as an alternative Community residents can contact local these are used as drinking water sources.
onsite disposal method for lots deemed health agency officials to find out about Regulations typically require minimum
unsuitable for conventional septic tank/soil regulations in their area. The National Small separation distances or buffer zones from
absorption systems. Because irrigation sys- Flows Clearinghouse (NSFC) also offers ground and surface water resources and
tems are designed to deliver wastewater information about federal and state regu- public areas to minimize contact with
slowly at rates beneficial to vegetation, and lations. (Refer to the contacts list on page 7 wastewater.
because the wastewater is applied either to and the products information on page 8.) Other important site selection criteria
the ground surface or at shallow depths, include the type of soil, soil wetness,
irrigation may be permitted on certain sites Pretreatment Is Required slope, drainage patterns, and local cli-
with high bedrock, high groundwater, or After wastewater receives primary and mate, including rainfall amounts and
slowly permeable soils. Irrigation systems sometimes secondary treatment in a com- evaporation rates. In areas that have cold
also can be designed to accommodate sites munity treatment plant or individual onsite or wet weather part of the year, waste-
with complex terrains. treatment system, additional treatment steps water often must be stored in lagoons or
Local governments sometimes choose often are required prior to irrigation to holding tanks until irrigation is needed.
to reuse wastewater from community reduce the amount of suspended solids and Some irrigation equipment also can freeze
treatment plants for irrigation, rather than organisms in the wastewater. Both can pose in very cold weather.
discharging all of it to local surface waters. a threat to public health and clog systems.
Irrigation can help communities to save Microorganisms, such as bacteria, can col- Maintenance Is Necessary
money or avoid exceeding surface dis- lect or multiply and create slime that clogs All systems, including irrigation sys-
charge permit limits, while preserving systems. Pretreatment also minimizes odors tems, have operation and maintenance
the quality of local water resources for in wastewater, so there is less potential for requirements. These include periodic
drinking water, aquatic life, and recreation. creating a public nuisance and attracting checking and cleaning of filters, checking
Some communities even have two sep- animals that can spread diseases. valves, pumps, and timers, and, in some
arate distribution systems—one for Different degrees of pretreatment are cases, monitoring wastewater quality and
potable water and another for reclaimed required for the wastewater depending on its impact on soils. Large systems serving
water for watering lawns and other how it will be used and the intended method farms, businesses, or communities often
irrigation needs. of irrigation. For example, standards are have operators, but most systems are at
more rigorous for surface irrigation methods, least partially automated.
Is it safe? such as spray irrigation, and when irrigating Although spray and subsurface drip
Irrigating with wastewater is safe when food or feed crops or land intended for pub- irrigation systems serving individual
all federal, state, and local regulations lic use. Biological pretreatment to remove homes may only need maintenance about
regarding its treatment and use are strictly organic matter from the wastewater is fol- once or twice per year, homeowners
followed. When regulatory requirements lowed by filtration, to remove small parti- should consider that these systems will
are met, the wastewater returned to the cles from the wastewater, and disinfection. require more attention than conventional
environment after irrigation usually Subsurface drip irrigation systems also onsite systems.
2 employ filters mainly to protect against
PIPELINE - Winter 1999; Vol.10, No. 1 National Small Flows Clearinghouse 1-800-624-8301
 SPRAY & DRIP IRRIGATION

Spray Systems Irrigate Lawns, Parks, Crops

1 House Sewer 3 Septic Tank 5 Sand Filter 7 Pump Chamber

Example 2 Septic Tank 4 Dosing Tank 6 Cl2 Disinfection 8 Spray System

residential
spray system
1
schematic 8

2 3

4 5 6 7

Spray irrigation is an efficient way to Chlorination is the most common disin- Another design used to irrigate row
nourish plants and apply reclaimed waste- fection method used with spray irrigation. crops, called a portable irrigation reel, is
water to land. Some spray systems are One common chlorinator design accepts a little less high-tech. It consists of a hard
very similar to potable-water sprinkler chlorine tablets or powder; another doses plastic hose wound to a drum reel. One
systems used to irrigate lawns. Others liquid chlorine into the wastewater. With end of the hose is attached to a portable
are specifically designed for agricultural chlorination, adequate contact time is sprinkler cart, which is pulled away from
applications. necessary to allow the chlorine time to the reel during setup, and the other end of
While there are many possible spray sys- kill harmful bacteria and other pathogens. the hose is attached to a hydrant. A motor
tem designs, they all work by distributing A holding tank or lagoon is another nec- or turbine rewinds the reel and crops are
treated wastewater across the soil surface. essary component in most spray systems, irrigated as the sprinkler cart moves along
Systems should be designed by qualified because storage space allows operators to the uncultivated irrigation paths, which
professionals who have specific experience adjust application rates, if needed. In must be kept clear for this purpose.
working with irrigation systems. some onsite systems that employ a recir- There also is a variety of sprinkler
culating sand filter, the recirculation tank designs for irrigating smaller field crops,
System Design serves as the storage tank. However, spray lawns, and landscaping, which are similar
Because spray systems apply effluent systems in cold or wet climates may need to potable-water lawn sprinkler systems.
above-ground, the wastewater must be to store 130 days of design flow or more. The sprinklers can be fixed (called solid-
treated to a high enough level to protect Systems may be permitted to apply waste- set) or moveable, buried or above-ground,
public health and reduce odors. In general, water only certain months of the year, or and some designs are telescoping to adjust
regulations require that effluent used for they may be required to include subsur- the height of application to fit the height
surface irrigation at least meet secondary face drainage to help prevent runoff and of the plants. Other variations exist in
treatment standards plus disinfection. erosion during wet weather. the amount of pressure and manner in
With spray systems, therefore, after Large community systems sometimes which the wastewater is released from the
primary treatment in a septic tank or com- reduce the amount of storage area they sprinklers—examples include full circle,
munity treatment plant, the wastewater need by obtaining controlled discharge partial circle, gun, and microspray. Dif-
usually goes to a home aerobic treatment permits, which allow them to release ferent pressure amounts are appropriate
unit, sand filter, recirculating sand filter, wastewater to surface water in winter or for irrigating different plant types. Indi-
or other filter, and then to a dosing tank during times of high stream flows. vidual home systems use low trajectory
or pump chamber. The wastewater is then sprinklers to minimize aerosol production.
disinfected with chlorine, ozone, or ultra- Spray Equipment Fixed, buried sprinkler systems usually
violet light before it is stored in a lagoon There is an impressive array of high-tech are among the most expensive designs to
or holding tank for later use or just prior spray equipment available for irrigating purchase and install, but they have certain
to its application to land. In some com- crops. Some consist of series of sprinkler advantages. They are less likely to be van-
munity systems, aerated or facultative heads mounted to elevated distribution dalized or accidently damaged and they
lagoons provide treatment as well as pipes, which move across fields either make maneuvering farm equipment and
additional storage area for the wastewater. laterally, by means of drive units at both lawn mowers easier. However, some
After treatment, filtration, and disinfec- ends of the pipe (called linear move), or moveable system components can be
tion, a pump equipped with timers sends in a circular motion from one fixed end stored indoors in the winter. Most spray
the wastewater under pressure through the (called pivot move). The height and system designs include valves and con-
mains and lines of the spray distribution amount of pressure with which the spray trols that allow operators or homeowners
system at preset times and rates as needed nozzles emit wastewater can be adjusted. to adjust the flow to certain areas of the
for irrigation. The area to be irrigated Systems even can be programmed to spray field. Some larger systems have
(the spray field) can be sloped up to 30 adjust application rates for different parts both automated and manual controls.
percent, depending on local regulatory of the field and to shut off automatically continued on page 4
requirements, but must be vegetated and during rain or high winds. And some can
landscaped to minimize runoff and erosion. be operated remotely.
3
PIPELINE - Winter 1999; Vol.10, No. 1 National Small Flows Clearinghouse 1-800-624-8301
 SPRAY & DRIP IRRIGATION

Some Advantages of Spray Spray Systems Irrigate Farmers must schedule irrigation times
and rates carefully, always adjusting for
Systems Include . . . Lawns, Parks, Crops different rainfall and evaporation amounts.
Some use devices, such as tensiometers,
continued from page 3
• When properly designed, to measure soil wetness, and rain gauges
installed, and operated, most
spray systems provide uniform
Setbacks and Buffer Zones and pan evaporation tests to keep track of
To guard against the possibility that irrigation needs. Spray irrigation of crops
distribution of wastewater to also needs to be scheduled around applica-
plants and eliminate discharge drifting aerosols and runoff created by
spray irrigation systems will reach and tions of pesticides and fungicides to plants.
to streams. Scheduling the irrigation of other types
• Above-ground irrigation is need- contaminate nearby public areas and
water resources, regulations typically of spray fields is usually less complicated.
ed for some germinating plants.
require considerable minimum setback Unrestricted public access sites, such as
• Spray irrigation increases levels
distances or buffer zones to nearby resi- the lawns of homes or businesses, land-
of nitrogen, phosphorus, and
scaping, parks, highway medians, and golf
minerals in the soil. dences, property lines, public areas, wells,
• Above-ground spray system streams, rivers, lakes, and wetlands. courses, often are irrigated only at night or
components are easier to Minimum setbacks of as much as 150 to during off-hours to minimize the potential
inspect, control, and service 500 feet from neighboring residences and for public contact with the wastewater.
than subsurface drip irrigation water sources are not unusual, depending Small systems and systems serving indi-
components. on local regulations. Buffers also may be vidual homes often are designed to apply a
• When performed during the required from water lines, embankments, set amount of wastewater twice a week or
heat of the day it has a cooling drains, drainage ditches, and public rights so at predetermined rates and times. The
effect on some crops and deco- system designer estimates the amount
of way. A minimum vertical separation
rative landscape plants. needed based on records showing average
distance to the water table also applies.
• Evaporation contributes to the precipitation and evaporation rates in the
Because of these setback requirements,
rate of wastewater disposal. area. Homeowners usually can adjust or
spray systems tend to be mainly practical
for irrigating crops, fields, and larger land override the pump settings if needed.
Some Disadvantages of areas or home lots. If a system is designed and sized primarily
Spray Systems Include . . . for wastewater disposal, the loading rates
Operation and Scheduling permitted for the wastewater may be below
• Spray systems generate Unlike traditional irrigation systems the irrigation needs of the plants. Therefore,
aerosols, which can pose a whose sole purpose is to deliver water to additional water may be required for irriga-
threat to public health. Therefore, plants, several additional factors must be tion with some systems.
regulations typically require large
Monitoring and Maintenance
considered when managing wastewater
minimum setback distances,
irrigation systems. The timing and rate of
buffers, and other restrictions The pump, disinfection system, and
wastewater application must be designed so
that make spray systems spray heads in spray irrigation systems
inappropriate for small lots. that plants benefit as much as possible from
the nutrients and other constituents in the require regular maintenance. For example,
• Wet soil surface promotes weed the chlorine tablets in chlorinators need to
growth, making some crops and wastewater without being overwhelmed by
them. In addition, there is the potential that be replenished regularly—approximately
landscaping difficult to maintain.
certain wastewater constituents may accu- once per month for home systems. Open
• Wet soil surface makes weeding,
mulate in the soil and plants over time and pipes and spray heads can become dam-
harvesting, and operating lawn
aged, plugged, or frozen. Any changes in
mowers and farm equipment become toxic to the plants, clog the soil, or
more difficult. alter the soil structure. pressure in the system can alter the spray
• Applications of insecticides and For example, too much nitrogen can result patterns in the field, so spray patterns
fungicides to crops must be in nitrate accumulation in crops, but too little should be tested to ensure that the system
scheduled carefully between can result in reduced yields. If evaporation still complies with all setback requirements.
spray irrigation applications to regularly exceeds precipitation, too much Other monitoring requirements vary
allow maximum contact/ salt may remain in the soil, which can depending on state and local regulations,
exposure times. damage roots. The particular characteristics public access to the site, and system size.
• Above-ground spray equipment In some systems, regular daily or weekly
of the wastewater must be considered in
is exposed to the elements and monitoring is needed to check influent
relation to such factors as climate and the
can be accidentally damaged or and effluent quality, system storage capac-
individual nutrient requirements of the
vandalized. ity, wind speed and direction, signs of
• Bacteria tends to survive better crops, grass, or landscape plants selected.
In addition, the need to dispose of the ponding or runoff in the spray field, and
in wet, cool soil conditions. depth to water table. Cumulative levels of
wastewater has to be balanced with the
needs of the plants during various stages nutrients, heavy metals, fecal coliforms,
of growth and the hydraulic capacity of the and other wastewater constituents must be
soil and its ability to effectively provide monitored in the soils (and groundwater)
4 treatment. at some sites once or twice per year.

PIPELINE - Winter 1999; Vol.10, No. 1 National Small Flows Clearinghouse 1-800-624-8301
 aa
SPRAY & DRIP IRRIGATION

Subsurface Drip Irrigation Systems Have Many Advantages

a
a Drip irrigation systems (also known as
“trickle” systems) are another efficient
and proven technology many small com-
munities can chose to recycle and dispose
of wastewater. Drip irrigation technology
using treated wastewater is used in Israel
and throughout the world as a way to con-
serve water resources. These systems
require less water than spray systems to
irrigate plants, and the technology has been
used for more than 30 years for various
agricultural and landscape applications.

Subsurface Drip Systems

Deliver Effluent to Plant Roots
With drip systems, treated wastewater is
applied to soil slowly and uniformly from
a network of narrow tubing (0.5- to 0.75-
inch diameter), usually plastic or polyeth-
ylene, placed either on the ground surface
or below ground at shallow depths of 6 to
12 inches in the plant root zone. The
wastewater is pumped through the tubes
under pressure, but drips out slowly from
a series of evenly-spaced openings. The
openings may be simple holes or, as is
the case in most subsurface systems, they
may be fitted with turbulent flow or pres-
sure-compensating emitter devices. These
emitter designs are proprietary and vary
depending on the manufacturer of the
system. (The graphic below is meant
to illustrate a generic subsurface drip
tube design.)

Example drip tubing

PIPELINE - Winter 1999; Vol.10, No. 1

Drip system emitters are designed to
ensure that the wastewater is always
released at the same slow rate at atmos-
pheric pressure, even though the water
pressure inside the tubes can range from 5
to 70 pounds per square inch (psi) during
a dosing cycle. However, most systems
are engineered to maintain relatively con-
sistent pressure inside the tubes, usually
about 20 psi. The pressure-compensating
feature of emitters allows drip irrigation
lines to be installed at different elevations
at a site while maintaining uniform flow.
Because subsurface drip systems release
wastewater below-ground directly to plant
roots, they irrigate more efficiently and
have advantages different from those of
surface irrigation systems. For example,
the soil surface tends to stay dry, which
means there is less water lost to evapora-
tion and there is almost no opportunity for
the wastewater to come in contact with
plant foliage, humans, or animals. Also,
percolation losses are reduced because the
wastewater is applied to a wide area of
soil at a slow rate directly to plant roots.
In addition, in drip systems the waste-
water is delivered to the most biologically
active part of the soil, which enhances
treatment and minimizes the possibility of
groundwater contamination. The constant
moisture in the root zone also may
increase the availability of nutrients to
plants, reducing the delivery of nitrogen
to groundwater. (Refer to page 6 for a list
of some advantages and disadvantages of
subsurface drip systems.)

Other System Design Elements

As with spray irrigation systems, waste-
water must be pretreated prior to drip
irrigation to protect public health and the
environment and to prevent systems from
clogging. Settleable and floatable solids are
removed by primary treatment, which may
take place in a community treatment plant
or lagoon or on individual home lots in a
septic tank or home aerobic treatment unit.
Primary treatment always is followed by
filtration in a particle-size filter to protect
the tubing from clogging.
In most systems, effluent flows to a tank
or pump chamber equipped with controls,
where it is stored until a predetermined
dosing volume is reached. All drip systems
are equipped with a filtration system before
the distribution system, such as a series of
disc filters or mesh screen filter membranes,
to remove small suspended solid materials
from the wastewater that can clog tubes
and emitters. Some systems also include
a disinfection step to protect public health.
The U.S. Environmental Protection
Agency approves the use of the chemical
trifluralin to prevent root intrusion into
emitters, although some states may not
permit it. One manufacturer of drip system
tubing incorporates a chemical barrier to
root intrusion directly into the tubing mate-
rial itself. However, the consistently wet
conditions in the soil and the pressure
compensating emitter design discourages
root growth into the distribution lines.
The distribution system in subsurface
drip systems usually includes a mainline,
submain, and narrow drip laterals with
emitters. The total length of drip tubing
will depend on the restrictiveness of the
site, the area needing irrigation, and the
amount of storage space available. The
laterals normally are installed in narrow
trenches (approximately 10 centimeters
wide) dug with a vibratory plow. Because
of the flexibility of the laterals and their
shallow placement, drip lines can be laid
around trees and other topographic features
with little disturbance to the site.
continued on page 6
5
National Small Flows Clearinghouse 1-800-624-8301
 SPRAY & DRIP IRRIGATION

Advantages of Subsurface
scale buildup develops on emitters, an
Drip Systems Include . . . Subsurface Drip acid treatment may be necessary.
• Water and nutrients are delivered
Systems Have Many
Setbacks and Buffer Zones
directly to plant roots.
• Less water is required when irri-
gating with drip systems than with
Advantages As with spray irrigation systems, regu-
spray systems and other suface continued from page 5 lations typically require that drip systems
irrigation methods. be installed at minimum distances from
The submains supply the amount of
• Wastewater is distributed more nearby residences, property lines, public
evenly with drip systems than water required by the individual laterals it
feeds, and valves are located between the areas, wells, surface water resources, and
spray systems and open irrigation
trenches. main and the submains to control the flow groundwater. However, because drip sys-
• Evaporation losses and weed of water to different parts of the system. tems deliver wastewater below ground
growth are reduced because the and do not produce aerosols, buffer zones
soil surface remains dry.
• Operating lawnmowers and farm
Clogging of 25 to 50 feet are generally required to
Drip system emitter clogging was more neighboring residences—considerably
equipment is easier because system
of a problem in the past than it is today. less than is required for spray systems,
components are buried and the soil
surface stays dry. Root intrusion into the drip tubing and making drip disposal more practical for
• There is no aerosol generation and no internal clogging from the buildup of sed- smaller home lots.
wastewater contact with plant foliage. iment, suspended solids, algae, and bacte-
• Crops irrigated with drip systems rial slime have been diminished greatly by Operation, Maintenance, and
can be harvested sooner than when
better pretreatment, filtration, disinfection, Scheduling
irrigated with spray systems. As with spray systems, drip irrigation
• Fewer problems exist with odors, and new tubing and emitter designs. Most
systems allow weekly or biweekly forward must be scheduled so that plants benefit
ponding, and runoff.
• There is less chance of wastewater flushing of the tubes to scouring velocity to from the nutrients and other constituents
carrying additional chemicals, such as remove slime and sediment buildup. in the wastewater without being over-
pesticides and fungicides, from the The size of the emitter orifices also is whelmed by them, and the needs of the
ground surface to groundwater. plants must be balanced with the capacity
important to prevent clogging and should
• Studies suggest nitrogen in wastewater of the soil to treat the most restrictive
may be better absorbed by plants and range from four to six times the maximum
size of the particles that can pass through components in the wastewater. These
less likely to pollute groundwater when
applied directly to plant roots. the mesh of the filter screen preceding the concerns must be balanced in turn with
• In some cases, fewer pretreatment distribution system. For example, a system climate and other site factors.
steps are required for wastewater with using a filter screen size of 115 microns Less labor usually is required for oper-
drip systems. ating and maintaining fixed subsurface
(140 mesh) should have emitters approxi-
• It is less likely that subsurface drip drip system components as compared to
components can be accidently or mately 800 microns in diameter to achieve
about a six-to-one ratio. spray systems and surface drip systems
intentionally damaged.
• Flexible tubing can accommodate sites When even a few emitters do clog, it can with moveable components. For small
with complex topographies. affect the pressure inside the tubes and the and individual home systems, the pattern
• There are generally fewer operation uniformity of wastewater distribution in of flow may be fixed or adjusted manual-
and maintenance requirements than the field. It also may be difficult to identify ly or automatically by the homeowner
with spray systems. or operator, depending on the system
and service buried emitters that clog. And
like traditional soil absorption systems design and sophistication. In general, the
Disadvantages of Subsurface used with septic systems, saturation of the best care for subsurface drip systems is
Drip Systems Include . . . soil around the emitters of a drip system provided by following the individual
• Emitters can potentially clog, affecting can eventually lead to the formation of a manufacturer recommendations.
the uniformity of application. biological clogging mat, which can cause Some communities may require home-
• Temporary use of sprinklers or other system failure. However, in general, sub- owners and small system owners to main-
surface irrigation may be necessary tain a service contract with an authorized
during plant germination period.
surface drip systems are considered to be
a manageable and reliable technology. manufacturer’s representative to ensure
• It is difficult to monitor and correct
Filters on all drip systems need to be appropriate monitoring and maintenance.
potential emitter clogging.
• Effects of freezing temperatures on checked and periodically backflushed or Larger systems often have full-time oper-
drip systems and applying wastewater cleaned. Backflushing reverses the water ators to maintain and service systems and
to frozen ground is still the subject of flow through the lines and the filters to to control the pattern of wastewater flow
study and debate. to irrigate different crops or fields. Some
release trapped sediments. Some systems
can be set up to backwash automatically systems can be operated and monitored
at preset intervals, or operators can do it remotely through telemetry.
manually as needed. The wastewater flow Refer to the list of NSFC documents on
needs to checked periodically to deter- page 8 and the list of contacts on page 7
mine if any emitters are plugging. If a for more detailed information on subsur-
6 face drip systems.
PIPELINE - Winter 1999; Vol.10, No. 1 National Small Flows Clearinghouse 1-800-624-8301
 SPRAY & DRIP IRRIGATION

Wisconsin Drip System Is an “Educational Opportunity”

If you were to pinpoint the center of “Because we are working with the uni-
Wisconsin on a map, you just might find versity, we were able to get an experimen-
Nasonville Elementary School. Located tal permit for a drip system,” Rodenbeck
in the rural Marshfield School District, said. “Graduate students from the univer-

CONTACTS
in the middle of dairy country, Nasonville sity regularly monitor the system’s per-
has plans to consolidate with another local formance, which is good for us and an
school adding 67 students to the 95 cur- educational opportunity for them.”
rently enrolled. But before health officials
would approve the additional students, the
Nasonville’s new system is sized to
handle 2,500 gallons of wastewater flows
The National Small Flows
school needed to upgrade its old waste- per day, which is enough to accommodate Clearinghouse (NSFC)
The NSFC offers technical assistance and
water system. approximately 350 students. Rodenbeck
free and low-cost information about onsite
“In our part of Wood County, we have estimated the system size needed by and small community wastewater techno-
some of the densest clay soils ever seen,” checking daily water use at other area logies and issues, including spray and drip
explained Paul Rodenbeck, the school dis- schools. The system consists of a 3,000- irrigation, wastewater reuse, and state and
trict’s building and grounds director. “For gallon septic tank equiped with a Zabel™ federal regulations. Only a few of the NSFC’s
years, the school’s wastewater system filter at the outlet. From the septic tank many resources and services are mentioned
in this issue. Visit the NSFC’s Web site at
consisted of a septic tank that discharged the wastewater flows to a recirculation www.nsfc.wvu.edu, or call (800) 624-8301 or
across an open field. Because of the diffi- tank where the wastewater is pumped to a (304) 293-4191 for assistance or to request a
cult local site conditions (heavy silt loam recirculating gravel filter. After treatment free catalog.
over massive clays), our options for in the gravel filter, the wastewater returns
upgrading were somewhat limited.” to the recirculation tank and then flows to Local and State Health Agencies
Holding tanks are the only new onsite an intermediate settling tank equipped For more information about spray and drip
wastewater systems being permitted in the with another Zabel™ filter at the outlet. irrigation, local regulations, or permit require-
area. But Rodenbeck, a former municipal Next, the wastewater flows to a dosing ments, community residents should contact
their local or county health department
wastewater treatment plant operator, was tank where it is sent to the drip distribu-
officials. Community leaders who wish to
inspired to research possible onsite waste- tion system. evaluate irrigation as an alternative to direct
water treatment alternatives for the school. “The system is designed to dose over discharge should contact their state health
One option that may have been appropri- a 24-hour period,” explained Rodenbeck. agency. State and local agencies usually are
ate for Nasonville was a mound system, The drip system itself has four zones or listed in the government section or blue
but the school was not keen on the way cells and takes up about one acre of the pages of local phone directories.
it might look on the school grounds, the 10-acre school lot.
earthwork involved, or the prospect of Rodenbeck said that the system has Extension Service Offices
Many universities have U.S. Department
having to mow it. Repair costs were anoth- been working well. “Due to mechanical
of Agriculture Extension Service offices on
er concern. “Even if only one part of the problems, the gravel filter was taken out campus and in other locations, which provide
system needs to be repaired, the mound of service during the winter, and we had a variety of services and assistance to indi-
has to be dug up,” Rodenbeck said. to bypass the filter all together,” he said. viduals and small communities. For the
Rodenbeck’s inquiries led him to work “The university requested that we not fix number of the Extension Service office in
your area, check the government pages of
with Duane Grueul of the Wood County this problem, but, instead, operate the
your local phone directory, call the NSFC,
Planning and Zoning Department. Grueul system with just the septic tank effluent or call the U.S. Department of Agriculture
suggested several area design firms that going through the drip system filters and directly at (202) 720-3377.
have experience with onsite systems. He then to the drip lines. The system has
also introduced Rodenbeck to Dr. James been working fine this way. None of the The Irrigation Association (IA)
Converse of the University of Wisconsin’s emitters have plugged and I haven’t even The IA is the irrigation industry’s trade organi-
Small Scale Waste Management Project, had to clean the filters. The gravel filter zation and has members who can provide
professional assistance in all aspects of irri-
one of the first research programs in the will be modified and be online for the start
gation. IA members include researchers,
country to study onsite systems. of school.” technicians, manufacturers, distributors, deal-
The firm the school chose for the proj- The university students continually ers, system designers, consultants, installers,
ect, Ayres and Associates of Madison, monitor the performance of the system and contractors. Visit its Web site at www.
worked together with Dr. Converse, and levels of bacteria in the soil as well as irrigation.org to conduct a search of IA’s
Grueul, and Rodenbeck to design a solu- investigate the effect of temperature on membership or for consumer information,
including how to hire an irrigation contractor.
tion for the site—namely, a subsurface the levels of bacteria in the soil.
Or, contact IA headquarters in Fairfax,
drip system. The system was installed in To learn more about Nasonville’s system Virginia, at (703) 573-3551 for assistance.
August 1998 and is part of the University and the University of Wisconsin study, con-
of Wisconsin’s research project. tact Dr. Converse at (608) 262-1106.
7
PIPELINE - Winter 1999; Vol.10, No. 1 National Small Flows Clearinghouse 1-800-624-8301
 RESOURCES AVAILABLE FROM NSFC
SPRAY & DRIP IRRIGATION

To order any of the following products, Computer Search: Drip Irrigation Free Brochure: Water Reuse Via Dual
call the National Small Flows Clearing- This booklet is a compilation of article Distribution Systems
house (NSFC) at (800) 624-8301 or (304) abstracts on drip irrigation compiled from This free brochure examines the benefits
293-4191, fax (304) 293-3161, e-mail a search of the NSFC’s Bibliographic of a wastewater reuse system and includes
nsfc_orders@estd.wvu.edu, or write Database. Complete copies of the articles information on system operation, design,
NSFC, West Virginia University, P.O. Box can be ordered from the NSFC. The price cost, and public acceptance issues.
6064, Morgantown, WV 26506-6064. Be is $2.75. Request Item #WWBLCM18. Request Item #WWBRGN15.
sure to request each item by number and
title. A shipping and handling charge PIPELINE
will apply. Computer Search: Spray Systems L SMALL
NA
Spray systems as an alternative to conven-

FL
O

OW
NAT I
Spray and Drip Irrigation Technology

S
tional methods of wastewater disposal is
an equal opportunity/affirmative action

E
CL
Package the topic of this NSFC Bibliographic EA

S
R IN GHOU institution
Database search. Abstracts of spray system Pipeline is published quarterly by the National Small
A selection of useful articles about spray Flows Clearinghouse at West Virginia University,
articles are included. The price is $6.75.
and drip irrigation with wastewater is pre- P.O. Box 6064, Morgantown, WV 26506-6064
Request Item #WWBLCM19.
sented in this publication. The articles are
Pipeline is sponsored by:
chosen from the NSFC’s Bibliographic U.S. Environmental Protection Agency
Database. Onsite irrigation systems and Manufacturers and Consultants Database Washington D.C.
Customized searches of the NSFC’s Steve Hogye—Project Officer
the application of wastewater to forest Municipal Support Division
lands and parks are among the topics dis- Manufacturers and Consultants Database Office of Wastewater Management
cussed. Case studies also are included. are available upon request. Contact the
National Small Flows Clearinghouse
The price is $16.25. Request Item NSFC and ask to speak with a technical West Virginia University
#WWBKGN53. assistance specialist to request a search of Morgantown,WV
irrigation system manufacturers, dealers, Peter Casey—Program Coordinator
Andrew Lake—Special Technical Advisor
designers, consultants, and operators in
Guidelines for Water Reuse your area. The price varies. Request Item
Cathleen Falvey—Writer/Editor
Jill A. Ross—Associate Editor
This EPA manual presents federal guide- Kairi Frame—Graphic Designer
#WWPCCM16.
lines for implementing a water reuse sys- Permission to quote from or reproduce articles in
tem and how to evaluate water reclamation this publication is granted when due acknowledgement
and reuse opportunities. Chapters are Guide to State Level Onsite Regulations is given. Please send a copy of the publication in
This guide provides information about which information was used to the Pipeline editor at
devoted to each of the technical, financial, the address above.
legal, institutional, and public involve- state regulations regarding onsite waste- ISSN 1060-0043
ment considerations that a reuse planner water systems. Contacts, keywords, and Pipeline is funded by the United States Environmental Protection
Agency. The contents of this newsletter do not necessarily reflect the
might examine.The price is $30.00. definitions are included. The price is views and policies of the Environmental Protection Agency, nor does

Request Item #WWBKDM72. $12.50. Request Item #WWBKRG01. the mention of trade names or commercial products constitute
endorsement or recommendation for use.

Printed on recycled paper

For wastewater information, call the NSFC at (800) 624-8301 or (304) 293-4191

ADDRESS SERVICE REQUESTED

Morgantown, WV Morgantown, WV 26506-6064
Permit No. 34 P.O. Box 6064
8
U.S. Postage Paid
Nonprofit Organization
West Virginia University
National Small Flows Clearinghouse
PIPELINE - Winter 1999; Vol.10, No. 1 National Small Flows Clearinghouse 1-800-624-8301