Winter 1999 Vol. 10, No. 1

SMALL L F A L N O O W I T S

A

N

C L E E A S R U I N G H O

PipelineSmall 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 courses keep their large fair­ to land is that the soil provides additional Treated wastewater can ways looking so lush, healthy, treatment through naturally occuring be reused to irrigate . . . D and green all season long? physical, biological, and chemical pro­ The answer may surprise you. cesses. Irrigating with wastewater also 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. and industrial developments; Because water is such a precious com­ • landscaped areas around modity, recycling wastewater can have A Solution for “Problem” Sites residences; both economic and environmental benefits Irrigation systems often can be used in for communities. Irrigation also can be place of soil absorption fields (drainfields) • pasture grass; the most practical and environmentally­ to provide final treatment and disposal • highway medians; friendly way communities can dispose of of wastewater from individual onsite • golf courses; treated effluent from wastewater treatment sys­tems, such as septic systems and home plants and individual home systems. aerobic treatment units. As the demand • cemeteries; for land in rural areas is increasing, more • forests; Better for the Environment sites are being developed in places previ­ • trees, corn, alfalfa, and other feed, Currently, the most common way com ously considered unsuitable for onsite fodder, and fiber crops; and munity treatment plants dispose of waste­ systems. Irrigation sometimes is permitted • food crops. water after treatment is to discharge it to as an alternative wastewater disposal surface waters. However, as populations method for difficult sites, such as areas grow, the burden to local streams and with slowly permeable soils, shallow rivers is increasing. Reusing wastewater soils, or complex topographies. when they may be a good option for to irrigate land can help protect precious This Pipeline issue provides a brief homes, businesses, and communities. surface water resources by preventing overview of two types of wastewater Operation and maintenance issues also are pol­lution and by conserving potable water irrigation­ systems—spray systems and discussed. for other uses. sub­surface drip systems—how they work, Readers are encouraged to reprint Pipeline articles in local newspapers or include them in flyers, newsletters, or educational presentations. 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 wastewater­ the cost of building, operating, and main­ home, farm, business, or community. It also always be pretreated prior to irrigation and taining systems, which should be consid­ can be a good choice simply because it is an by restricting its quality, use, and the manner ered when determining whether irrigation efficient use of local resources. and location of its application. Cumulative is a practical wastewater disposal option. In arid climates, such as in Arizona, New levels of nutrients, salts, heavy metals, and Mexico, and parts of California, for exam­ disease-causing organisms also must be Site Conditions Are Important ple, or where the demand for water threatens­ monitored in the soil at some sites. Not all sites are appropriate for waste to exceed the supply, as it does in parts of water application. Communities wishing Florida, many homes and businesses could Regulations Vary to dispose of wastewater from treatment 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 dispos­al water. In Hawaii, treated wastewater is used and sometimes from community to commu­ or enter into cooperative arrangements to irrigate pineapples and sugar cane to save nity. State and local governments may have with local farmers or landowners. Sites money and conserve fresh water for other additional or more stringent requirements near surface water or high groundwater 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/ regulations in their area. separation distances or buffer zones from soil absorption systems. Because irrigation ground and surface water resources and systems­ are designed to deliver wastewater Pretreatment Is Required public areas to minimize contact with slowly at rates beneficial to vegetation, and After wastewater receives primary and wastewater. because the wastewater is applied either sometimes secondary treatment in a com­ Other important site selection criteria to the ground surface or at shallow depths, munity treatment plant or individual onsite include the type of soil, soil wetness, irrigation may be permitted on certain sites treatment system, additional treatment steps slope, drainage patterns, and local cli­mate, with high bedrock, high groundwater, or often are required prior to irrigation to including rainfall amounts and evaporation slowly permeable soils. Irrigation systems reduce the amount of suspended solids and rates. In areas that have cold or wet also can be designed to accommodate sites organisms in the wastewater. Both can pose weather part of the year, waste­water often with complex terrains. a threat to public health and clog systems. must be stored in lagoons or holding tanks Local governments sometimes choose Microorganisms, such as bacteria, can col­ until irrigation is needed. Some irrigation to reuse wastewater from community lect or multiply and create slime that clogs equipment also can freeze in very cold treatment plants for irrigation, rather than systems. Pretreatment also minimizes odors weather. discharging all of it to local surface waters. in wastewater, so there is less potential for Irrigation can help communities to save creating a public nuisance and attracting Maintenance Is Necessary money or avoid exceeding surface discharge­ animals that can spread diseases. All systems, including irrigation sys­ permit limits, while preserving Different degrees of pretreatment are tems, have operation and maintenance the quality of local water resources for required for the wastewater depending on requirements. These include periodic drinking water, aquatic life, and recreation. how it will be used and the intended method checking and cleaning of filters, checking Some communities even have two separate­ of irrigation. For example, standards are more valves, pumps, and timers, and, in some distribution systems—one for rigorous for surface irrigation methods, such cases, monitoring wastewater quality and potable water and another for reclaimed as spray irrigation, and when irrigating food its impact on soils. Large systems serving water for watering lawns and other irrigation or feed crops or land intended for public­ use. farms, businesses, or communities often needs. Biological pretreatment to remove organic have operators, but most systems are at matter from the wastewater is fol­lowed by least partially automated. Is it safe? filtration, to remove small particles­ from the Although spray and subsurface drip Irrigating with wastewater is safe when all wastewater, and disinfection. irrigation systems serving individual federal, state, and local regulations regarding Subsurface drip irrigation systems also homes may only need maintenance about its treatment and use are strictly followed. employ filters mainly to protect against once or twice per year, homeowners should When regulatory requirements are met, the consider that these systems will require wastewater returned to the more attention than conventional onsite environment after irrigation usually systems. 2 PIPELINE - Winter 1999; Vol.10, No. 1 SPRAY & DRIP IRRIGATION Spray Systems Irrigate Laws, 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 very One common chlorinator design accepts a little less high-tech. It consists of a hard similar to potable-water sprinkler systems chlorine tablets or powder; another doses plastic hose wound to a drum reel. One 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 kill the reel during setup, and the other end of While there are many possible spray sys­ 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 some must be kept clear for this purpose. working with irrigation systems. onsite systems that employ a recir­culating There also is a variety of sprinkler sand filter, the recirculation tank serves as designs for irrigating smaller field crops, System Design the storage tank. However, spray systems lawns, and landscaping, which are similar Because spray systems apply effluent in cold or wet climates may need to store to potable-water lawn sprinkler systems. above-ground, the wastewater must be 130 days of design flow or more. Systems The sprinklers can be fixed (called solid­ treated to a high enough level to protect may be permitted to apply waste­water only set) or moveable, buried or above-ground, public health and reduce odors. In general, certain months of the year, or they may be and some designs are telescoping to adjust regulations require that effluent used for required to include subsur­face drainage to the height of application to fit the height of surface irrigation at least meet secondary help prevent runoff and erosion during wet the plants. Other variations exist in treatment standards plus disinfection. 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 for unit, sand filter, recirculating sand filter, wastewater to surface water in winter or irrigating different plant types. Indi­vidual or other filter, and then to a dosing tank during times of high stream flows. home systems use low trajectory sprinklers or pump chamber. The wastewater is then 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 to spray equipment available for irrigating purchase and install, but they have certain its application to land. In some com­munity crops. Some consist of series of sprinkler advantages. They are less likely to be systems, aerated or facultative lagoons heads mounted to elevated distribution van­dalized or accidently damaged and provide treatment as well as additional pipes, which move across fields either they make maneuvering farm equipment storage area for the wastewater. laterally, by means of drive units at both and lawn mowers easier. However, some After treatment, filtration, and disinfec­ ends of the pipe (called linear move), moveable system components can be tion, a pump equipped with timers sends or in a circular motion from one fixed stored indoors in the winter. Most spray the wastewater under pressure through the end (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 adjust spray field. Some larger systems have both (the spray field) can be sloped up to 30 application rates for different parts of the automated and manual controls. percent, depending on local regulatory field and to shut off automatically during continued on page 4 requirements, but must be vegetated and rain or high winds. And some can be landscaped to minimize runoff and erosion. operated remotely. 3 PIPELINE - Winter 1999; Vol.10, No. 1 SPRAY & DRIP IRRIGATION

Spray Systems Irrigate Farmers must schedule irrigation times Some Advantages of Spray 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, installed, to measure soil wetness, and rain gauges and operated, most spray systems and pan evaporation tests to keep track of provide uniform distribution of Setbacks and Buffer Zones To guard against the possibility that irrigation needs. Spray irrigation of crops wastewater to plants and eliminate also needs to be scheduled around applica­ discharge to streams. drifting aerosols and runoff created by tions of pesticides and fungicides to plants. • Above-ground irrigation is need­ed spray irrigation systems will reach and Scheduling the irrigation of other types for some germinating plants. contaminate nearby public areas and water of spray fields is usually less complicated. • Spray irrigation increases levels resources, regulations typically require of nitrogen, phosphorus, and considerable minimum setback distances or Unrestricted public access sites, such as minerals in the soil. buffer zones to nearby resi­dences, property the lawns of homes or businesses, land­ • Above-ground spray system lines, public areas, wells, streams, rivers, scaping, parks, highway medians, and golf components are easier to lakes, and wetlands. Minimum setbacks of courses, often are irrigated only at night or inspect, control, and service as much as 150 to 500 feet from neighboring during off-hours to minimize the potential than subsurface drip irrigation residences and water sources are not for public contact with the wastewater. components. unusual, depending on local regulations. Small systems and systems serving indi­ • When performed during the heat Buffers also may be required from water vidual homes often are designed to apply of the day it has a cooling effect lines, embankments, drains, drainage ditches, a set amount of wastewater twice a week on some crops and deco­rative and public rights of way. A minimum vertical or so at predetermined rates and times. landscape plants. separation distance to the water table also The system designer estimates the amount • Evaporation contributes to the rate needed based on records showing average of wastewater disposal. applies. Because of these setback requirements, precipitation and evaporation rates in the area. Homeowners usually can adjust or Some Disadvantages of spray systems tend to be mainly practical for irrigating crops, fields, and larger land areas override the pump settings if needed. Spray Systems Include . . . or home lots. If a system is designed and sized primarily for wastewater disposal, the loading rates • Spray systems generate aerosols, Operation and Scheduling permitted for the wastewater may be below which can pose a threat to public the irrigation needs of the plants. Therefore, Unlike traditional irrigation systems health. Therefore, regulations additional water may be required for irriga­ whose sole purpose is to deliver water to typically require large minimum tion with some systems. setback distances, buffers, and plants, several additional factors must be other restrictions that make spray considered when managing wastewater Monitoring and Maintenance systems inappropriate for small irrigation systems. The timing and rate of wastewater application must be designed so The pump, disinfection system, and spray lots. heads in spray irrigation systems require • Wet soil surface promotes weed that plants benefit as much as possible from regular maintenance. For example, the growth, making some crops and the nutrients and other constituents in the chlorine tablets in chlorinators need to be landscaping difficult to maintain. wastewater without being overwhelmed by replenished regularly—approximately once • Wet soil surface makes weeding, them. In addition, there is the potential that harvesting, and operating lawn certain wastewater constituents may accu­ per month for home systems. Open pipes mowers and farm equipment more mulate in the soil and plants over time and and spray heads can become dam­aged, difficult. become toxic to the plants, clog the soil, or plugged, or frozen. Any changes in pressure • Applications of insecticides and alter the soil structure. in the system can alter the spray patterns in fungicides to crops must be For example, too much nitrogen can result the field, so spray patterns should be tested scheduled carefully between spray in nitrate accumulation in crops, but too little to ensure that the system still complies with irrigation applications to allow can result in reduced yields. If evaporation all setback requirements. maximum contact/ exposure times. regularly exceeds precipitation, too much salt Other monitoring requirements vary • Above-ground spray equipment may remain in the soil, which can damage depending on state and local regulations, is exposed to the elements and roots. The particular characteristics of the public access to the site, and system size. can be accidentally damaged or wastewater must be considered in relation In some systems, regular daily or weekly vandalized. to such factors as climate and the individual monitoring is needed to check influent • Bacteria tends to survive better in and effluent quality, system storage capac­ity, wet, cool soil conditions. nutrient requirements of the crops, grass, or landscape plants selected. wind speed and direction, signs of ponding In addition, the need to dispose of the or runoff in the spray field, and depth to wastewater has to be balanced with the needs water table. Cumulative levels of nutrients, of the plants during various stages heavy metals, fecal coliforms, and other of growth and the hydraulic capacity of the wastewater constituents must be monitored soil and its ability to effectively provide in the soils (and groundwater) at some sites 4 treatment. once or twice per year. PIPELINE - Winter 1999; Vol.10, No. 1 SPRAY & DRIP IRRIGATION Subsurface Drip Irrigation Systems Have Many Advantages

Drip irrigation systems (also known as Drip system emitters are designed to to groundwater. (Refer to page 6 for a list “trickle” systems) are another efficient ensure that the wastewater is always of some advantages and disadvantages of and proven technology many small com­ released at the same slow rate at atmos­ subsurface drip systems.) munities can chose to recycle and dispose pheric pressure, even though the water of wastewater. Drip irrigation technology pressure inside the tubes can range from 5 Other System Design Elements As using treated wastewater is used in Israel to 70 pounds per square inch (psi) during with spray irrigation systems, waste and throughout the world as a way to a dosing cycle. However, most systems are water must be pretreated prior to drip conserve­ water resources. These systems engineered to maintain relatively consistent­ irrigation to protect public health and the require less water than spray systems to pressure inside the tubes, usually about 20 environment and to prevent systems from irrigate plants, and the technology has been psi. The pressure-compensating feature of clogging. Settleable and floatable solids are used for more than 30 years for various emitters allows drip irrigation lines to be removed by primary treatment, which may agricultural and landscape applications. installed at different elevations at a site take place in a community treatment plant or while maintaining uniform flow. lagoon or on individual home lots in a septic Subsurface Drip Systems Because subsurface drip systems release tank or home aerobic treatment unit. Primary wastewater below-ground directly to plant treatment always is followed by filtration Deliver Effluent to Plant Roots roots, they irrigate more efficiently and in a particle-size filter to protect the tubing With drip systems, treated wastewater have advantages different from those of from clogging. is applied to soil slowly and uniformly surface irrigation systems. For example, In most systems, effluent flows to a tank from a network of narrow tubing (0.5- to the soil surface tends to stay dry, which or pump chamber equipped with controls, 0.75inch­ diameter), usually plastic or means there is less water lost to evapora­ where it is stored until a predetermined polyethylene,­ placed either on the ground tion and there is almost no opportunity for dosing volume is reached. All drip systems surface or below ground at shallow depths the wastewater to come in contact with are equipped with a filtration system before of 6 to 12 inches in the plant root zone. plant foliage, humans, or animals. Also, the distribution system, such as a series of The wastewater is pumped through the percolation losses are reduced because the disc filters or mesh screen filter membranes, tubes under pressure, but drips out slowly wastewater is applied to a wide area of soil to remove small suspended solid materials from a series of evenly-spaced openings. at a slow rate directly to plant roots. from the wastewater that can clog tubes and The openings may be simple holes or, as In addition, in drip systems the waste­ emitters. Some systems also include is the case in most subsurface systems, water is delivered to the most biologically a disinfection step to protect public health. they may be fitted with turbulent flow or active part of the soil, which enhances The U.S. Environmental Protection pressure­ -compensating emitter devices. treatment and minimizes the possibility of Agency approves the use of the chemical These emitter designs are proprietary and groundwater contamination. The constant trifluralin to prevent root intrusion into vary depending on the manufacturer of the moisture in the root zone also may increase emitters, although some states may not system. (The graphic below is meant the availability of nutrients to plants, permit it. One manufacturer of drip system to illustrate a generic subsurface drip tube reducing the delivery of nitrogen tubing incorporates a chemical barrier design.) to root intrusion directly into the tubing material­ itself. However, the consistently wet conditions in the soil and the pressure Example drip tubing 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 PIPELINE - Winter 1999; Vol.10, No. 1 SPRAY & DRIP IRRIGATION

Advantages of Subsurface Drip Systems Include . . . Subsurfae Drip scale buildup develops on emitters, an • Water and nutrients are delivered directly acid treatment may be necessary. to plant roots. Systems Have Many • Less water is required when irri- Setbacks and Buffer Zones gating with drip systems than with spray Advantages As with spray irrigation systems, regu­ systems and other suface irrigation continued from page 5 lations typically require that drip systems methods. be installed at minimum distances from • Wastewater is distributed more The submains supply the amount of nearby residences, property lines, public evenly with drip systems than water required by the individual laterals it spray systems and open irrigation feeds, and valves are located between the areas, wells, surface water resources, trenches. main and the submains to control the flow and groundwater. However, because drip • Evaporation losses and weed of water to different parts of the system. sys­tems deliver wastewater below ground growth are reduced because the and do not produce aerosols, buffer zones soil surface remains dry. Clogging of 25 to 50 feet are generally required to • Operating lawnmowers and farm neighboring residences—considerably equipment is easier because system Drip system emitter clogging was more components are buried and the soil of a problem in the past than it is today. less than is required for spray systems, 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 Scheduling irrigated with spray systems. better pretreatment, filtration, disinfection, As with spray systems, drip irrigation • Fewer problems exist with odors, and new tubing and emitter designs. Most ponding, and runoff. systems allow weekly or biweekly forward must be scheduled so that plants benefit • There is less chance of wastewater flushing of the tubes to scouring velocity to from the nutrients and other constituents carrying additional chemicals, such remove slime and sediment buildup. in the wastewater without being over­ as 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 • Studies suggest nitrogen in wastewater important to prevent clogging and should of the soil to treat the most restrictive may be better absorbed by plants and range from four to six times the maximum less likely to pollute groundwater when size of the particles that can pass through components in the wastewater. These 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 steps distribution system. For example, a system climate and other site factors. are required for wastewater with drip using a filter screen size of 115 microns Less labor usually is required for oper­ systems. (140 mesh) should have emitters approxi­ ating and maintaining fixed subsurface • 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 intentionally damaged. about a six-to-one ratio. spray systems and surface drip systems • 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 and uniformity of wastewater distribution in of flow may be fixed or adjusted manual­ maintenance requirements than with the field. It also may be difficult to identify ly or automatically by the homeowner spray systems. and service buried emitters that clog. And or operator, depending on the system like traditional soil absorption systems design and sophistication. In general, Disadvantages of Subsurface used with septic systems, saturation of the the best care for subsurface drip systems Drip Systems Include . . . soil around the emitters of a drip system is provided by following the individual • Emitters can potentially clog, affecting the can eventually lead to the formation of a manufacturer recommendations. 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 surface drip systems are considered to be tain a service contract with an authorized during plant germination period. manufacturer’s representative to ensure • It is difficult to monitor and correct a manageable and reliable technology. potential emitter clogging. Filters on all drip systems need to be appropriate monitoring and maintenance. • Effects of freezing temperatures on drip checked and periodically backflushed or Larger systems often have full-time oper­ systems and applying wastewater to cleaned. Backflushing reverses the water ators to maintain and service systems and frozen ground is still the subject of study flow through the lines and the filters to to control the pattern of wastewater flow and debate. release trapped sediments. Some systems to irrigate different crops or fields. Some 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 needs to checked periodically to deter­mine 6 if any emitters are plugging. If a PIPELINE - Winter 1999; Vol.10, No. 1 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 in the middle of dairy country, Nasonville univer­sity regularly monitor the system’s has plans to consolidate with another local per­formance, which is good for us and an CONTACTS school adding 67 students to the 95 cur­ educational opportunity for them.” rently enrolled. But before health officials Nasonville’s new system is sized to would approve the additional students, the handle 2,500 gallons of wastewater flows school needed to upgrade its old waste­water per day, which is enough to accommodate system. approximately 350 students. Rodenbeck “In our part of Wood County, we have estimated the system size needed by some of the densest clay soils ever seen,” checking daily water use at other area Local and State Health Agencies explained Paul Rodenbeck, the school schools. The system consists of a For more information about spray and drip dis­trict’s building and grounds director. 3,000­gallon septic tank equiped with irrigation, local regulations, or permit require­ “For years, the school’s wastewater system a Zabel™ filter at the outlet. From the ments, community residents should contact consisted of a septic tank that discharged septic tank the wastewater flows to a their local or county health department across an open field. Because of the recirculation tank where the wastewater officials. Community leaders who wish to evaluate irrigation as an alternative to direct diffi­cult local site conditions (heavy silt is pumped to a recirculating gravel filter. discharge should contact their state health loam over massive clays), our options for After treatment in the gravel filter, the agency. State and local agencies usually upgrading were somewhat limited.” wastewater returns to the recirculation are listed in the government section or blue Holding tanks are the only new onsite tank and then flows to an intermediate pages of local phone directories. wastewater systems being permitted in the settling tank equipped with another area. But Rodenbeck, a former municipal Zabel™ filter at the outlet. Next, the Extension Service Offices wastewater treatment plant operator, was wastewater flows to a dosing tank where inspired to research possible onsite waste­ it is sent to the drip distribution­ system. Many universities have U.S. Department water treatment alternatives for the school. “The system is designed to dose over of Agriculture Extension Service offices One option that may have been appropri­ a 24-hour period,” explained Rodenbeck. on campus and in other locations, which ate for Nasonville was a mound system, The drip system itself has four zones or provide a variety of services and assistance but the school was not keen on the way cells and takes up about one acre of the to indi­viduals and small communities. For the number of the Extension Service office it might look on the school grounds, the 10-acre school lot. in your area, check the government pages earthwork involved, or the prospect of Rodenbeck said that the system has of your local phone directory, or call the U.S. having to mow it. Repair costs were anoth­ been working well. “Due to mechanical Department of Agriculture directly at (202) er concern. “Even if only one part of the problems, the gravel filter was taken out 720-3377. system needs to be repaired, the mound has of service during the winter, and we had to be dug up,” Rodenbeck said. to bypass the filter all together,” he said. The Irrigation Association (IA) Rodenbeck’s inquiries led him to work “The university requested that we not fix with Duane Grueul of the Wood County this problem, but, instead, operate the The IA is the irrigation industry’s trade organi­ Planning and Zoning Department. Grueul system with just the septic tank effluent zation and has members who can provide suggested several area design firms that going through the drip system filters and professional assistance in all aspects of irri­gation. IA members include researchers, have experience with onsite systems. He then to the drip lines. The system has technicians, manufacturers, distributors, also introduced Rodenbeck to Dr. James been working fine this way. None of the deal­ers, system designers, consultants, Converse of the University of Wisconsin’s emitters have plugged and I haven’t even installers, and contractors. Visit its Web site Small Scale Waste Management Project, one had to clean the filters. The gravel filter at www. irrigation.org to conduct a search of of the first research programs in the country will be modified and be online for the start IA’s membership or for consumer information, including how to hire an irrigation contractor. Or, to study onsite systems. of school.” contact IA headquarters in Fairfax, Virginia, at The firm the school chose for the proj­ect, The university students continually (703) 573-3551 for assistance. Ayres and Associates of Madison, worked monitor the performance of the system together with Dr. Converse, Grueul, and and levels of bacteria in the soil as well Rodenbeck to design a solu­tion for the as investigate the effect of temperature on site—namely, a subsurface the levels of bacteria in the soil. drip system. The system was installed in To learn more about Nasonville’s system 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