Livestock Manure Storage

Improperly managed manure can contami-nate both surface and ground water withnutrients and disease-causing organisms.Storing livestock manure allows producers tospread it when crops can best use the nutri-ents. However, accumulating manure in a con-centrated area can be risky to the environmentand to human and animal health unless doneproperly.

Federal and state drinking water standardsstate that nitrate levels in drinking watershould not exceed 10 milligrams per liter(equivalent to parts per million for water mea-sure). Nitrate nitrogen levels higher than thiscan pose health problems for infants under 6months of age, including the condition knownas methemoglobinemia (blue baby syndrome).Nitrate also can affect adults, but the evidenceis much less certain.

Young livestock also are susceptible to healthproblems from high nitrate nitrogen levels.Levels of 20 to 40 mg/l in the water supplymay be harmful, especially in combinationwith high levels (1,000 ppm) of nitrate nitrogenfrom feed sources.

Facilities for manure stored in liquid formmay sometimes leak or burst, releasing largevolumes of pollutants. Manure stored in earth-en pits can form a semi-impervious seal oforganic matter and bacterial cells on the bot-tom and sides. The seal limits leaching, butseasonal filling and emptying can cause theseal to break down. Short-term solid manurestorage areas and abandoned storage areas alsocan be sources of ground water contaminationby nitrates.

Livestock wastes (manure and wastewater)should be stored in an environmentally soundmanner until they can be applied to land.Regulations of the Texas Natural ResourceConservation Commission (TNRCC) apply tothe location of and minimum standards forseepage control from lagoons and detentionponds. Dry manure can be stored in stockpiles,and liquid manure can be stored in lagoonsand detention ponds. The environmental safetyof collecting large amounts of manure in oneplace for an extended period depends on thefollowing items:

1. location of the storage site with respect tophysical and chemical characteristics ofthe soil;

2. subsurface geologic materials and theirstructure;

3. design and construction of the storage siteor facility, including control of seepage;and

4. proper land application of the manureonce it leaves the storage site or facility, ata rate compatible with nutrient uptake bycrops based on current soil test.

Manure stored in solid or liquid form can beapplied most efficiently to the soil at thosetimes of the year when crops are not activelygrowing. This allows solid manure to be tilledin immediately after application, or liquidmanure slurry to be injected into the soil.Liquid manure also can be stored in lagoonswhere bio-degradation occurs and then appliedto land by irrigation. Handling manure in thisway ensures that fertilizer nutrients from thewaste materials will be used by crops, whilereducing risks of ground water and surfacewater contamination. Once manure is appliedand incorporated, a forage crop will be plantedto use the nutrients.

Stored manure can be easily sampled andtested to determine its nitrogen, phosphorusand potassium levels. When sampling manure,be sure to obtain as representative a sample aspossible. This usually involves taking a numberof subsamples (10 or more) and mixing theminto one or more samples to be analyzed. Withmanure tests and a knowledge of the amountof manure applied per acre, a farmer can deter-mine whether additional commercial fertilizeris needed to meet crop production goals.

Waste storage also reduces the need to applyit to land during winter months when manyforage crops are dormant. It conserves nutri-ents contained in the manure and minimizesmanure nutrient leaching and runoff. Storageis also valuable during extended periods of badweather which make application impractical.Texas Natural Resource ConservationCommission rules prohibit irrigation withwastewater when the ground is frozen or satu-rated.

A glossary at the end of this publication willclarify terminology. The following topics arecovered:

1) Long-term storage

2) Short-term storage

3) Waste storage location

4) Lining materials for lagoons, detentionponds or stroage pits

5) Other management factors

6) Abandoned pits

7) Evaluation table

Long-term Storage

Livestock wastes can be stored either insolid, semi-solid, or liquid states.

★ Solid waste facilities use walls and slabsfor stacking heavily-bedded manure.

★ Semi-solid waste facilities use pumps orscrapers to move manure into contain-ment areas, and may separate solids fromliquids.

★ Liquid waste facilities hold manure intanks, pits, waste storage ponds orlagoons.

Liquid and semi-solid storage systems areself-contained. Ground water contaminationcan occur if the facility is not structurallysound and waste materials are allowed to leakout into the soil. Surface water can be threat-ened if pits are not emptied frequently enoughto prevent wastes from flowing over the top ofthe structure.

Liquid storage systems require the use ofpipes and/or pumps for moving wastes fromthe barn to the storage structure. These mustbe carefully installed and maintained to checkfor leakage. After emptying, carefully checksteel and concrete structures for cracks or theloss of watertight seals, and repair them imme-diately. Likewise, check the bottom and sidesof earthen waste storage pits and lagoons to becertain the liner materials have not been erod-ed away by agitation and pumping. Fine-tex-tured soil materials become “self-sealed” to alimited degree through bacterial clogging of soilpores. However, this seal can be destroyedthrough mechanical cleaning processes.

After a period of years, weathering, waveaction, or wetting and drying cycles may causethe side walls of earthen pits to crack anderode. This allows waste to seep into theunderlying soil or subsurface geologic material.Ground water contamination will result if thesubsurface materials do not prevent leaching ofcontaminants.

While seepage from earthen waste storagefacilities is not always easy to recognize, thereare some tell-tale signs, including the following:

★ A properly designed structure has thecapacity to handle wastes from a specificnumber of animals for a known numberof days. For example, if a pit or ponddesigned for 180 days of storage andreceiving designated waste amounts hasnot needed pumping for a year or more,the structure is probably leaking.

★ Evaporation from a liquid manure storagepit is minimal if a crust forms. If addition-al liquids have to be added before the pitscan be agitated and pumped, they may beleaking. (Monitoring wells installedaround the pit upslope and downslopecould be used to confirm the seepage.)

Some facilities for storing semi-solid manureare designed to allow seepage from the wastestack. In these instances, structural designmust include collection and treatment of thewaste seepage. These systems should not beused on sites with coarse-textured soils,creviced bedrock or shallow water tables. Thebest way to handle seepage is to channel it intoa watertight holding pond or storage tank.

In areas where the construction of a holdingpond is not feasible, another option is to builda covered semi-solid manure storage structureto eliminate additional water being added tothe manure stack. Roofed storage systemsrequire adequate bedding to absorb and retainthe liquid portion of the waste.

Short-term Storage

Short-term storage (usually 30 to 90 days) isan important option available to producers. Itallows them to hold livestock wastes duringperiods of bad weather when daily spreadingmay not be feasible.

Short-term storage, which is restricted pri-marily to solid or semi-solid manure, has thedisadvantage of requiring that the manure behandled more than once. Some designs forshort-term storage structures facilitate handlingand provide effective protection for surface andground water.

Short-term storage systems may be used byproducers who stack manure in fields, particu-larly during periods of bad weather or betweencropping cycles. However, this is not a recom-

mended practice. No matter how it is done, itmay pose a contamination threat to surface andground water. If manure is stacked in fields, arunoff detention pond must be constructed atthe storage site.

Many farmers have open housing for younglivestock, such as pole sheds, where wastes areallowed to accumulate for extended periods oftime. Roofs on these structures keep rain andsnow off the manure. These structures are rela-tively safe for water quality if they are protect-ed from surface water runoff. To minimizewater contamination, provide adequate bed-ding to reduce seepage, and clean these shedsfrequently.

Waste Storage Location

The location of livestock waste storage inrelation to any well is an important factor inprotecting the farm water supply. For tempo-rary manure stacks and earthen storage facili-ties, the minimum separation distance is 150feet in Texas.

Minimum separation distances regulate newwell installation as well as the distance fromexisting wells to new waste storage facilities.Existing wells are required by law only to meetseparation requirements in effect at the time ofwell construction. Make every effort, however,to exceed “old regulations,” and to meet currentregulations whenever possible.

Observing these separation distances whensiting a new facility is a good way to help pro-tect your drinking water. Locating manure stor-age sites or facilities downslope from the wellis also important for protecting your water sup-ply. For more information about separation dis-tances, and how the condition of your wellmight affect the potential for contamination,see TEX*A*Syst publication B-6024, ImprovingWell Head Management and Conditions.

While observing the well separation dis-tances may protect your own well, poorlydesigned or poorly maintained livestock wastestorage facilities could still contaminate theground water. Protecting ground waterresources can help protect your neighbors’wells and drinking water supplies, as well asyour own.

Depth to water table or fractured bedrock,along with soil type, is an important factor.These are among the site vulnerability charac-

teristics described in B-6023, TEX*A*SystIntroduction.

The depth to water table is sometimes foundin the narrative section of the county soil sur-vey, but this varies from county to county. Yourcounty Extension agent or Natural ResourcesConservation Service office may also be able tohelp you gather this information.

Lining Materials for Lagoons,Detention Ponds or Storage Pits

The Texas Natural Resource ConservationCommission is responsible for implementingregulations that govern confined, concentratedlivestock and poultry feeding operations. Toprotect ground water from seepage fromlagoons or holding ponds, TNRCC regulationsrequire that wastewater retention facilities beconstructed of compacted or in-situ soil materi-als at least 12 inches thick and with low per-meability. The soil material must meet orexceed the following criteria:

★ liquid limit of 30 percent or more;

★ plasticity index of 15 or more; and

★ fraction passing a number 200 mesh sieveof 30 percent or more.

Many lagoons also are required to have clayliners that are nearly impermeable (permeabili-ty coefficient of 1X 10-7 cm/sec).

Other Management Factors

If animal waste storage causes any signifi-cant water contamination, the Texas NaturalResource Conservation Commission (TNRCC)can impose a fine and require corrective mea-sures. Contact your county Extension agent orlocal Natural Resources Conservation Serviceoffice for information about local ordinances,state regulations and other available assistance.

Abandoned Pits

Abandoned waste storage pits, especiallyearthen ones, can pose significant water qualityproblems. Any abandoned structure should becompletely emptied. In the case of earthenwaste storage facilities, liner materials shouldbe removed to a depth of about 2 feet and thenspread over disposal areas. The remaining holeshould be filled and leveled. Manure packsfrom pole barns or sheds no longer in use also

should be removed, and the wastes applied todisposal areas.

Evaluation Table

The following table can help agriculturalproducers and rural homeowners determinethe risk that drinking water on a given proper-ty may become contaminated as a result of the

management practices being used. For eachcategory listed on the left that is appropriate,read across to the right and circle the state-ment that best describes conditions on yourland. Allow 15 to 30 minutes to complete thetable, and skip any categories that do notapply. Note any high risk ratings and takeappropriate actions to remedy them. Strive forall low or low-moderate risk ratings.

Livestock Manure Storage: Assessing Drinking Water Contamination Risk

Low Risk Low-Moderate Risk Moderate-High Risk High Risk

Long-Term Storage (180 days or more)

Steel, glass-lined Designed and in- Designed and installed Leaking tank on Leaking tank on(liquid-tight design, stalled according to according to accepted medium-textured soils coarse-texturedabove ground) accepted engineering engineering standards (silt loam, loam). soils (sands, sandy

standards and specifi- and specifications. Not Water table deeper loam). Water tablecations. Properly maintained. than 20 feet. or fractured bed-maintained. rock shallower

than 20 feet.

Concrete (liquid- Designed and in- Designed and installed Concrete cracked, Concrete cracked,tight design) stalled according to according to accepted medium-textured soils coarse-textured

accepted engineering engineering standards (silt loam, loam). soils (sands, sandystandards and specifi- and specifications. Water table deeper loam). Water tablecations. Properly Not maintained. than 20 feet. or fractured bed-maintained. rock shallower

than 20 feet.

Poured concrete Designed and in- Designed and installed Concrete cracked, Concrete cracked,(liquid-tight design) stalled according to according to accepted medium-textured soils coarse-textured

accepted standards engineering standards (silt loam, loam). soils (sands, sandy and specifications. and specifications. Not Water table deeper loam). Water tableProperly maintained. maintained. than 20 feet. or fractured bed-

rock shallowerthan 20 feet.

Earthen waste Designed and in- Not designed to Not designed to stalled according to engineering standards. engineering stand-

storage pit (below accepted engineering Constructed in ards. Constructedground) standards and specifi- medium- or fine-textur- in coarse-textured

cations. Properly ed dense materials materials (sands,maintained and lined. (silt loams, loam, clay sandy loam).

loams, silty clay). Fractured bedrock Water table deeper or water table than 20 feet. Earthen shallower than 20 lining eroding. feet. More than 10

years old. Earthen lining perforated.

Short-Term Storage (usually 30-90 days; in some cases, up to 180 days)

Stacked in field Stacked on high Stacked on high(on soil base) ground. Medium- or ground. Coarse-

fine-textured soils (silt textured soilsloam, loam, clay (sands, sandyloams, silty clay). loam). FracturedWater table deeper bedrock or waterthan 20 feet. table shallower

than 20 feet.

Livestock Manure Storage: Assessing Drinking Water Contamination Risk

Low Risk Low-Moderate Risk Moderate-High Risk High Risk

Short-Term Storage (usually 30-90 days; in some cases, up to 180 days) (continued)

Stacked in yard* Covered concrete Concrete yard with Earthen yard with Earthen yard withyard with curbs, curbs and gutters. medium- or fine-textur- coarse-texturedgutters and settling ed soils (silt loam, soils (sands,basin. loam, clay loams, sandy loam).

silty clay). Water table Fractured bedrockdeeper than 20 feet. or water table

shallower than 20 feet.

Water-tight structure Designed and install- Designed and installed Designed and installed Designed and in-designed to accept- ed in clay soils to engineering stan- according to engineer- stalled according ed engineering according to engi- dards on medium- or ing standards on to engineeringstandards and neering standards. fine-textured soils (silt coarse-textured soils standards. Not specifications All liquids retained. loam, loam, clay (sands, sandy loam). properly main-

loams, silty clay). With Water table or frac- tained. Waterclay liners. Water table tured bedrock treatment, diver-deeper than 20 feet. shallower than 20 feet. sion and terrace

structures allowed to deteriorate.

Stacked in open Building has concrete Building has earthenhousing floor, protected from floor on coarse-textur-

surface water runoff. ________ ed soils (sands, sandy ________Adequate bedding loam), subject to sur-provided. face water runoff.

Water table or frac-tured bedrock shallower than 20 feet.

Location

Location of live- Manure stack or Manure stack or Manure stack or Manure stack orstock waste storage earthen waste stor- earthen waste storage earthen waste storage earthen wastein relation to drink- age pit more than pit more than 250 feet pit less than 250 feet storage pit lessing water well 250 feet downslope upslope from well. downslope from well. than 250 feet up-

from well. Manure Manure storage struc- Manure storage struc- slope from well.storage structure ture (liquid-tight) more ture (liquid-tight) less Manure storage(liquid-tight) more than 100 feet upslope than 100 feet down- structure (liquid-than 100 feet down- from well. slope from well.* tight) less thanslope from well. 100 feet upslope

from well.

*See Glossary.

Glossary

Concrete stave storage: A type of liquid-tightanimal manure storage structure. Locatedon a concrete pad, it consists of concretepanels bound together with cable or boltsand sealed between panels.

Earthen basin or pit: Clay-lined manure orwastewater storage facility constructedaccording to specific engineering standards.

Engineering standards: Design and construc-tion standards available at NaturalResources Conservation Service (NRCS)offices. These standards may come fromNRCS technical guides, state regulations, orland grant university engineering hand-books.

Filter strip: A grassy area used to filter andsettle solids from livestock yard runoff andsome types of solid manure storage sys-tems. Waste is distributed uniformly acrossthe high end of the strip and flows down-slope. Nutrients and suspended material inthe runoff water are partially filtered out bythe grass, absorbed by the soil and taken upby plants. Filter strips must be designedand sized to match the characteristics of thelivestock yard or storage system.

Glass-lined steel storage: A type of liquid-tight, above-ground animal manure storagestructure. Located on a concrete pad, it con-sists of steel panels bolted together andcoated inside and outside with glass to pro-vide corrosion protection.

Poured concrete storage: A type of liquid-tight animal manure storage structure.Located on a concrete pad, it consists ofpoured concrete reinforced with steel.

Water table depth: Depth to the upper sur-face of ground water. This depth is some-times indicated in the county soil survey,but this varies from county to county. Thisinformation may be available from yourwell construction report or from hydrogeo-logical reports and ground water flow mapsof your area. Your county Extension agentor NRCS representative may also be able tohelp you gather this information.

There are two types of water tables: (1) thewater table typically noted in a well log asan indication of useable water supply; and(2) the seasonal high water table. The sea-sonal high water table is most important inregard to construction of livestock manurestorage facilities, because it may presentfacility construction problems.

Contacts and References

For additional information contact yourlocal county Extension agent, or:

★ Texas Natural Resource ConservationCommission at (512) 239-1000,

★ Texas Agricultural Extension ServiceAgricultural Engineering unit (409) 845-7451,

★ Texas Agricultural Extension Service WaterQuality unit (409) 845-0887,

★ Texas State Soil and Water ConservationBoard, (817) 773-2250.

Internet address: TEX*A*Syst bulletins andlinks to other water quality sites are containedin a homepage located on the World Wide Webat: http://waterhome.tamu.edu.

TEX*A*Syst is a series of publications to help rural residents assess the risk of ground water pollution, and to describeBest Management Practices (BMPs) that can help protect ground water. The TEX*A*Syst documents were developedfrom the national Farm*A*Syst ground water protection program. The TEX*A*Syst system is designed to help the userlearn more about the environment, existing environmental policies and regulations, and recommended managementpractices. Thus, the user can voluntarily reduce the pollution risks associated with water wells.

TEX*A* Syst materials were edited by Anna Schuster Kantor, and reviewed by M.C. Dozier and the personnel of theUSDA-Natural Resources Conservation Service, U.S. Environmental Protection Agency, Texas Department ofAgriculture, Texas Natural Resource Conservation Commission, Texas Water Development Board, Texas State Soil andWater Conservation Board, Texas Water Resources Institute, and Texas Farm Bureau. Editorial and formatting assis-tance were provided by the Department of Agricultural Communications, The Texas A&M University System.

The TEX*A*Syst program is sponsored by the U.S. EnvironmentalProtection Agency under Section 319(h) of the Clean Water Act.Funds for this program are administered by the Texas State Soil andWater Conservation Board’s Agricultural/Silvicultural NonpointSource Management Program.