ID-120
Many livestock producers with confinement operations handle their animal waste as a liquid because of the labor-saving advantages. An integral part of many liquid handling systems is the livestock waste lagoon.
A livestock lagoon is actually a small-scale waste treatment plant, containing manure which has been diluted with building washwater, rainfall, waterer wastage and surface runoff. In this earthen, pond-like structure, the waste becomes partially liquefied and stabilized by bacterial action before eventual disposal on the land. Lagoons may contain one of three types of waste-stabilizing bacteria-anaerobic (inhibited by oxygen), aerobic (requiring oxygen) or facultative (maintained with or without oxygen).
This publication deals with the design, construction and management of livestock waste lagoons. Its purpose is to help a confinement operator: (1) assess the potential benefits of a lagoon to his waste handling program, (2) apply the principles of proper lagoon design and construction, and (3) understand the steps required to start up and maintain a biologically-active facility. At the end of this publication, a worksheet (with example) is provided for determining lagoon capacities and dimensions; also listed are sources of additional information concerning livestock waste handling.
Waste lagoons, properly designed and managed, offer confinement livestock operators the following advantages:
However, there are also some actual and potential disadvantages associated with livestock lagoons, the major ones probably being:
Livestock waste lagoons may be anaerobic or aerobic, single-stage or double-stage. Here are some characteristics of each type that should be considered in determining which one might best fit your situation.
Anaerobic lagoons are the ones most commonly used with liquid waste handling systems. There are some septic odors with this type, especially in the spring; however, serious odor problems seldom occur when the lagoon is designed and operated correctly. Where more complete odor control is necessary, mechanical aeration equipment can be used to add oxygen to the lagoon's surface layer, or the facility can be covered with plastic liners to prevent emission of odors into the air.*
Aerobic lagoons are either mechanically aerated or designed to be naturally aerobic. Required design volume for a mechanically-aerated lagoon is about half that of an anaerobic lagoon; whereas the volume of a naturally-aerobic unit should be 4-5 times greater than the anaerobic type. This volume, together with a 5-6 foot depth limit, requires a land area so large as to make naturally-aerobic lagoons generally impractical for farm use.
Two-stage lagoons (Figure 1) have some significant advantages over single-stage lagoons (Figure 2) when it comes to livestock waste handling. The first stage (or cell) is usually a deep, anaerobic structure that overflows into a shallower aerobic or facultative cell, producing an effluent with less odor and fewer organic solids than a single-stage lagoon. This is especially important where pumping of the effluent can cause plugging, such as when irrigating beef or dairy waste lagoons or when recirculating water from lagoon-to-building in a flushing system.
Also, since the liquid level of the first stage remains constant, more dilution water is available to treat and stabilize incoming waste. This, in turn, helps minimize odors.
A word of clarification: A holding pond or detention facility is not a waste treatment lagoon, but rather a smaller structure designed for short-term collection and storage of feedlot runoff. Little biological decomposition takes place in a runoff detention facility; therefore, if manure solids are not kept out, objectionable odors and rapid sludge accumulation will likely result. When pumped down, such a facility should be emptied completely and cleaned out.
Lagoon Volume
A waste treatment lagoon must be large enough to store diluted manure for a long enough period of time so that it can be decomposed by bacteria. Total design volume required for an efficient lagoon system is the sum of its minimum design volume, waste storage volume and dilution volume. However, the actual volume to be excavated includes this figure plus a safety factor called "freeboard".
The following paragraphs explain (and Figures 1 and 2 illustrate) these four components of lagoon volume. Table 1 then presents the volume recommendations for different types of livestock and different types of lagoons.
Minimum design volume is the space necessary to insure viable and adequate bacteria populations for continuous waste decomposition. Insufficient bacterial action means poor waste treatment and serious odor problems. Therefore, the liquid level of waste in a lagoon should never be allowed to drop below the minimum design volume figures shown in Table 1. (For example, a single-cell lagoon receiving swine waste must provide) 135 cubic feet for each 100-pound pig.)
Once-a-year dewatering Twice-a-year dewatering
--------------------------------- -------------------------------
Types of livestock One-stage Two-stage lagoon One-stage Two-stage lagoon
and lagoon volumes lagoon 1st stage 2nd stage lagoon 1st stage 2nd stage
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cu. ft./lb. liveweight cu. ft./lb. liveweight
Swine
Design volume 1.35 1.25 0.35 1.35 1.25 0.35
Storage volume 0.40 - 0.40 0.20 - 0.20
Dilution volume 0.40 - 0.40 0.20 - 0.20
----- ---- ----- ------ ----- ------
Total volume 2.15 1.25 1.15 1.75 1.25 0.75
Beef
Design volume 1.50 1.25 0.50 1.50 1.25
Storage volume 0.34 - 0.34 0.17 - 0.17
Dilution volume 0.34 - 0.34 0.17 - 0.17
------ ------ ----- ------ ----- -----
Total volume 2.18 1.25 1.18 1.84 1.25 0.84
Dairy
Design volume 1.75 1.50 0.50 1.75 1.50 0.50
Storage volume 0.50 - 0.50 0.25 - 0.25
Dilution volume 0.50 - 0.50 0.25 - 0.25
------ ----- ----- ----- ------ ------
Total volume 2.75 1.50 1.50 2.25 1.50 1.00
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Waste storage volume is the space required to store the waste produced by your livestock operation for a specific period of time. Length of that period depends on whether the lagoon is dewatered ("pumped down") once a year-or twice a year. Table 1 indicates the waste storage requirements for these two dewatering schedules. (Notice that neither waste storage nor dilution volumes apply to the first stage of a two-stage lagoon.)
Dilution volume is the amount of water that must be added to a lagoon system between each dewatering period to insure proper waste decomposition and to minimize odors. A lagoon may malfunction and build up high concentrations of organic matter and salts, unless it is regularly diluted. Under Indiana conditions, dilution volume should be about equal to the waste storage volume (see Table 1).
Common sources of dilution water are: building washwater, spillage from livestock waterers, feedlot runoff, and/or water pumped from a well. stream or pond. Rain which falls on the lagoon surface is generally ignored in determining dilution water supplies.
If added water from the above sources is insufficient, to meet dilution volume needs, surface drainage water could be diverted to the lagoon. (But don't divert more than needed!) Table 2 shows how much surface drainage area would supply sufficient dilution water volume to a lagoon system for various types of livestock. Under Indiana conditions, the drainage area required is about the same as the surface area of the lagoon. Size of the drainage area can be reduced by about 50 percent if roof gutter runoff is diverted to the lagoon.
Square feet of drainage
Type of livestock area per pound liveweight
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Swine 0.130 sq. ft.
Beef 0.110 sq. ft.
Dairy 0.165 sq. ft.
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*Assumes no washwater or waterer wastage from building.
If a drainage area cannot be diverted, another source of dilution water must be found. In Indiana, 8 gallons of well water added every 6 months will replace 1 square foot of drainage area.
Freeboard (or safety) volume is included in the design of a lagoon to allow for large and sudden amounts of rainfall. This extra capacity minimizes the chances of the lagoon overflowing once it has reached its total design volume. For Indiana, the freeboard should be 24 inches for all lagoons, including a 12-inch deep grass-sodded emergency spillway in the lagoon berm (Figures 1 and 2). Thus, if overflow does occur, the spillway will carry it off without destructive erosion to the lagoon dam. Suggested dimensions of the spillway are: 3-4 feet wide and 12 inches deep with a well-established grass drainageway sloped at not more than 1 foot of fall for each 20 feet of horizontal run.
A lagoon designed to be pumped every 6 months should be nearly "full" at the end of that time (i.e., water level at the bottom of freeboard). If this is not the case, either there hasn't been enough dilution water added or the structure has seepage problems.
Lagoon Dimensions
Once total lagoon volume has been calculated, dimensions of the structure(s) can be determined from Table 3. The table figures assume 2 feet of freeboard and a side slope of 2.5 to 1. This ratio of horizontal distance to rise or fall is suitable for most potential lagoon sites in Indiana. (The downstream exterior slope should be no less than 3:1 if it is to be grazed or 5:1 if it is to be mowed).
To use Table 3, first locate you calculated total lagoon volume figure in column 1, then read to the right to find the required interior length when you selected depth is 6, 10, 15, 20 feet and selected interior width is 100, 150, 200, 300, or 400 feet. For example, if you need a holding capacity of 100,000 cubic feet, can excavate to a 15-foot depth and are limited to a 100-foot width, the table shows that lagoon length must be 154.
Interior Length (feet) of Lagoon when --
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Lagoon Depth is 6 feet and -- Depth is 10 feet and -- Depth is 15 feet and -- Depth is 20 feet and --
Volume Interior width (feet) is -- Interior width (feet) is -- Interior width (feet) is -- Interior width (feet) is--
(cu.ft -------------------------- ------------------------ ----------------------- ----------------------------
x 1000) 100 150 200 300 400 100 150 200 300 400 100 150 200 300 400 100 150 200 300 400
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10 44 33 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
20 73 51 41 32 0 56 0 0 0 0 0 0 0 0 0 0 0 0 0 0
30 102 70 55 41 34 73 53 0 0 0 0 0 0 0 0 0 0 0 0 0
40 132 88 68 49 40 89 63 52 0 0 81 0 0 0 0 0 0 0 0 0
50 161 107 82 58 47 106 73 59 0 0 93 0 0 0 0 0 0 0 0 0
60 191 121 95 67 53 123 83 67 51 0 105 75 0 0 0 103 0 0 0 0
70 220 144 109 76 60 139 93 74 56 0 118 82 0 0 0 114 0 0 0 0
80 249 162 122 85 66 156 103 80 60 51 130 89 0 0 0 125 0 0 0 0
90 279 181 136 93 73 173 113 88 65 54 142 95 77 0 0 136 0 0 0 0
100 308 199 149 102 79 189 123 95 69 57 154 102 82 0 0 147 0 0 0 0
110 338 218 163 111 86 206 133 102 74 61 167 109 87 0 0 158 104 0 0 0
120 367 236 176 120 92 223 143 109 79 64 179 116 92 0 0 169 109 0 0 0
130 396 255 190 128 99 239 153 117 83 67 191 123 96 0 0 180 115 0 0 0
140 426 274 204 137 105 256 163 124 88 71 204 130 101 77 0 192 121 0 0 0
150 455 292 217 146 112 273 173 131 92 74 216 136 106 80 0 203 126 101 0 0
160 0 311 231 155 118 289 183 138 97 77 228 143 111 83 0 214 132 104 0 0
170 0 329 244 164 125 306 193 145 101 81 241 150 115 85 0 225 137 108 0 0
180 0 348 258 172 131 323 203 152 106 84 253 157 120 88 0 236 143 112 0 0
190 0 366 271 181 138 339 213 159 110 87 265 164 125 91 76 247 148 115 0 0
200 0 385 285 190 144 356 223 167 115 91 278 171 130 94 78 258 154 119 0 0
225 0 431 318 212 161 398 248 184 126 99 308 188 141 102 84 286 168 128 0 0
250 0 477 352 234 177 439 273 202 138 107 339 205 153 109 89 314 182 138 102 0
275 0 524 386 256 193 0 298 220 149 116 370 222 165 116 94 342 196 147 108 0
300 0 570 420 278 209 0 323 238 160 124 401 239 177 124 100 369 209 156 113 0
325 0 616 454 299 225 0 348 256 172 132 431 256 189 131 105 397 223 165 119 0
350 0 662 487 321 242 0 373 274 183 141 462 273 201 138 110 425 237 175 125 103
375 0 709 521 343 258 0 398 292 194 149 0 290 212 146 116 453 251 184 130 107
400 0 0 555 365 274 0 423 309 206 157 0 307 224 153 121 0 265 193 136 111
425 0 0 589 387 290 0 448 327 217 166 0 324 236 160 126 0 279 202 141 115
450 0 0 622 409 307 0 473 345 229 174 0 342 248 168 132 0 293 212 147 119
475 0 0 656 431 323 0 498 363 240 182 0 359 260 175 137 0 307 221 152 123
500 0 0 690 453 339 0 523 381 251 191 0 376 272 182 142 0 321 230 158 127
550 0 0 758 497 372 0 573 417 274 207 0 410 295 197 153 0 348 249 169 135
600 0 0 821 541 404 0 623 452 297 224 0 444 319 211 163 0 376 267 180 143
650 0 0 893 585 436 0 673 488 319 241 0 478 343 226 174 0 404 286 191 151
700 0 0 960 628 469 0 723 524 342 257 0 513 366 241 185 0 432 304 202 159
750 0 0 0 672 501 0 0 559 365 274 0 547 390 255 195 0 459 323 213 167
800 0 0 0 716 534 0 0 595 388 291 0 581 414 270 206 0 487 341 225 175
850 0 0 0 768 566 0 0 631 410 307 0 615 437 285 216 0 515 360 236 182
900 0 0 0 804 599 0 0 667 433 324 0 649 461 299 227 0 543 378 247 190
950 0 0 0 848 631 0 0 702 456 341 0 683 485 314 238 0 571 397 258 198
1000 0 0 0 892 664 0 0 738 479 357 0 718 508 329 248 0 598 415 269 206
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Note: Figures assume 2 feet of freeboard and 2.5:1 side slope
Lagoon depth depends somewhat on the type of equipment available for excavation; however, anaerobic and mechanically-aerated lagoons should be as deep as possible (Table 4). Consider limiting width, especially with beef or dairy lagoons, to 100 feet to permit sludge removal by dragline or chopper pump. And plan on making the berm (Figure 3) at least 8 feet at the top -- wide enough for any equipment needed in lagoon maintenance (mowing, tractor with PTO pump for irrigation, etc).
Type of lagoon Recommended depth ------------------------------------------------- Single-stage As deep as possible Two-stage First cell As deep as possible Second cell 6-10 feet Mechanically-aerated As deep as possible Naturally-aerobic Not used for livestock --------------------------------------------------
Remember, the total amount of land lost to lagoon construction includes not only the dimensions of the structure and the berm, but also what will be needed for slope on the outside of the lagoon. This can be substantial if the berm is very high above grade.
Lagoon Location
If possible, the livestock lagoon should be adjacent to the source of waste. More important in determining its location, however, are the following considerations:
1.The site should be as far from the farm house as practical and downwind from it. In Indiana, this means to the north, northeast or east of the house.
2.The site should be downhill and at least 100 feet from water wells and water courses.
3.The site should be selected with your neighbors in mind. Nuisance suits may result if objectionable odors are not controlled. To some, lagoon odors might be "objectionable" at a distance of 1/2 mile or more and "detectable" at even more than a mile. And since sight and smell are intimately related, try to hide the facility from public view with landscaping and buildings.
4. A lagoon constructed as part of a new livestock facility that requires Indiana State Board of Health approval must be at least 50 feet from public roads, 1000 feet from a neighboring residence, 1500 feet from a public building and 2000 feet from built-up areas of 5 or more houses-unless the Board of Health grants a special variance. (Also check local zoning ordinances when planning a lagoon, since some Indiana counties may require even greater distances.)
5. The lagoon should be downhill from the livestock confinement area, if possible, so that wastes can be carried to it by gravity (Figure 4). If it is level or uphill from the waste source, a sump with submersible sewage lift-type pump will be necessary. Piping used to gravity-transport the waste to either lagoon or sump should be at least 8 inches in diameter and have a slope of at least 1/16 inch per foot (0.5%). Place "Y" cleanouts in the line every 200 feet or less.
6. Although livestock manure is a good soil sealant (except in very coarse sand or gravel), nevertheless, try to locate the lagoon in the most impervious soil. Cooperative Extension or Soil Conservation Service personnel can help you determine a soil's suitability for lagoon construction.
Sites where the bottom of the structure would be in sand or within 10 feet of limestone should be avoided, although it may be possible to seal the bottom with plastic liners, a swelling-type clay, 6 inches of compacted topsoil or 4 inches of disked-in livestock manure. Also, if located in a high water table or shallow soil area, consider a cut-and-fill lagoon with sump-pump system (Figure 5).
A diversion terrace uphill from the lagoon may be necessary to prevent excess surface runoff from filling the lagoon. However, if possible, construct the terrace such that clean runoff could be channeled to the lagoon system if extra dilution water was needed. If a tile line crosses the proposed site, plug or remove the tile and relocate the line around the lagoon.
Lagoon Inlets and Overflows
Eight- to 10-inch PVC sewer pipe with glued joints or cement asbestos sewer pipe with driven or masonry joints work well for waste lagoon inlets. An inlet pipe should extend at least 20 feet into the lagoon, being supported every 8-10 feet. If the lagoon is very long, consider using more than one inlet to insure uniform loading. Also, make sure there is at least 5 feet of liquid depth at the inlet so that solids from the incoming waste will always be submerged.
An above-surface inlet should suffice for most lagoons that receive a small, continuous loading (Figure 6). A drawback, however, is that liquids can freeze in the pipe. To prevent this problem, drain the gutters or collection pits at least once a week during the winter rather than allowing constant flow. The pipe sections that are above the frost line should have enough slope to drain freely and thus minimize plugging. If the inlet is at least 2 feet above the lagoon surface, rodent entry should not be a problem.
A below-surface inlet requires a certain amount of water pressure to work properly, such as with a flushing system or with full pipe flow when a gutter or collection pit is emptied (Figure 7). However, the line can plug near the water level, especially in the case of liquid manure pit overflow ("trickle") loading. Therefore, lay the last section of pipe (that which extends below the lagoon surface) at a 14-inch-per-foot slope. Place a "Y" cleanout near the inlet end so it can be rodded and cleaned.
An overflow pipe (also called a "trickle tube") transports the solids-free waste water from first to second stage in a two-stage lagoon. It should be located as far as possible from the main inlet(s) so no untreated waste can get into it. The inlet end of an overflow pipe should be submerged at all times (even when there is wave action) to prevent any floating solids from reaching the second stage lagoon.
Two types of pipe will work as an overflow. One is 6-inch straight pipe with the inlet end about 1 foot lower than the outlet (Figure 8). This type is easily rodded from the second-stage lagoon side (outlet end).
The second type of overflow is a 5- to 8-inch pipe with a "T" junction at the inlet end and sloped toward the outlet end (Figure 9). The bottom of the "T" should be 5- 8 inches below the water level. If the "T" is located within 2-3 feet of the berm, the pipe can be easily rodded from the inlet side. Since this type of overflow is more susceptible to plugging, provide a grass-sodded spillway as a safeguard.
The Sump and Sump Pump
If the lagoon system is level with or above the confinement area, a sump pit and pump will be necessary to collect and lift the liquid waste and dilution water into the lagoon. The pump should be a commercial-grade sewage left-type (Figure 10) that is activated with a float switch. A mercury switch enclosed in a rubberized float (purchased separately) is very dependable. Some pumps come equipped with a diaphragm pressure switch built into the pump body, which has the same function as a float switch.
Most sewage pumps are open-impeller trash types and. thus, have limited lifting capability. For instance, a 3-inch sump pump operating at 1725 rpm can pump 200 gallons per minute (gpm) at 20 feet of head, 100 gpm at 30 feet of head and 20 gpm at 50 feet of head. Therefore, lift should be limited to about 20 feet. Consult Cooperative Extension personnel for assistance in designing your sump and pump loading system.
Although a 2-inch pump might be satisfactory for pumping livestock waste, a 3-incher will probably give more trouble-free operation. The sewer line from pump to lagoon should be the same size as the pump discharge to prevent solids from settling in the pipe. The pump should be able to handle 1 1/2-inch diameter solids and be sized to empty the sump in 5-10 minutes to prevent excess solids from settling to the bottom.
It is usually not economical to design a system large enough to handle the full flow of waste from a large liquid manure pit. Therefore, consider a small sump and pump system with a sluice gate at the pit outlet to regulate waste flow into the sump.
For pump servicing, a sump pit should be large enough for a repairman to work in (at least 3% feet in diameter). There should also be some means of preventing waste from flowing into the sump while servicing the pump, such as a gate valve in the inlet.
Minimizing Lagoon Construction Costs
Although it may seem expensive, a well-designed, large-volume lagoon system with long-term storage can usually be constructed for much less than a deep pit under slotted floor. And as size of a system increases, further savings are possible by building a large portion of the lagoon above ground (using cut- and-fill techniques). For a large lagoon, the amount saved on excavation should more than offset the cost of the sump and pump needed for an above-ground lagoon.
Many lagoon systems handle feedlot runoff as well as the concentrated manure. When the lot is scraped periodically and the scrapings hauled to the field, the lagoon receives less organic loading. In this case, only about half the total number of animals on the lot need to be considered in calculating lagoon design volume. If feed lot runoff is diverted through a well-operated settling basin, minimum design volume of the lagoon may be reduced to about 1/4 the total number of animals.
A settling basin for lot runoff should have a capacity of 1 cubic foot for each 12 square feet of lot area; and the basin should be cleaned out when it becomes half full with solids. (See Purdue Extension Publication ID-114, listed on page 14, for more information on runoff control systems) .
Starting Up a Lagoon
First, fill the lagoon with water to its minimum design volume before adding any waste. Loading should then be gradual so that the proper type of bacteria will "grow". This will also minimize odor problem.
Best time for start-up is early spring (March or April) to allow adequate bacterial cultures to become established before cold weather the next winter. Lagoons started in the fall and heavily loaded all winter may develop serious odor problems the following spring and summer; and it could take several years before good operation is possible.
Ideally, start-up should commence by adding about 1/4 of the lagoon's animal waste capacity during the first 2 months. Another 1/4 should be added over the next 2 months, and the third 1/4 over the fifth and sixth months. Finally, after 6 months, the lagoon should be ready receive the last 1/4 of its designed animal capacity. While if is usually not possible to follow this precise schedule in starting up a lagoon, nevertheless, the chances for "success" are greatly increased if loading can be done gradually.
Some odors will occur during start-up. If, they become severe, decrease the loading rate or begin the start-up procedure again. As the lagoon ages odors usually decrease and should be less each succeeding year.
Monitoring Sludge Build-Up
The amount of build-up of sludge (settled decomposing waste) in a lagoon over time is difficult to predict. For example, three swine lagoons at the University of Illinois had only about 1 to 1 1/2 feet of sludge after more than 15 years of operation; whereas some facilities have required sludge removal after only 3 years.
Generally, cattle lagoons have more rapid build-up than do swine lagoons. On the average, a well-designed beef or dairy lagoon will probably need cleaning out every 6-7 years, whereas one for swine might be expected to go 10 years before sludge removal.
Sludge build-up should be measured once a year as a check on the proper operation of the lagoon Rapid accumulation (i.e., a foot or more per year) signals improper operation and, thus. poor waste decomposition by the bacteria. Such build-up will also eventually decrease the lagoon's effective volume to the point where incomplete treatment and serious odor problems result.
Measurement of sludge depth can only be done accurately using a rowboat and measuring rod. Take the reading near the center of the lagoon but not within 15 feet of an inlet.
Determining the Lagoon
As soon as a lagoon becomes full (i.e., water level reaches the bottom of freeboard), it should be pumped down, preferably to its minimum design volume. This "dewatering" is generally done using irrigation equipment or, in some cases, manure tanker wagons if the lagoon is small.
Dewatering by Irrigation.Irrigation systems used for dewatering range from 2 hp gasoline pumps with 1 1/4- inch black plastic pipe and lawn-type sprinklers to PTO-driven 350 gpm pumps with "big guns" sprinklers. If the adjacent cropland is gently sloping away from the lagoon, low-cost 4-inch unperforated plastic drain pipe with 1/2-inch holes drilled every 6 inches can be used.
Size of the lagoon plus the solids content of the lagoon water will determine the type and size of irrigation equipment required for dewatering. Generally, the less solids in the water (such as with a single-stage swine lagoon and most second-stage lagoons), the smaller and less expensive the equipment needs to be.
Length of time required to dewater by irrigation is determined by the following formula (see worksheet section VII for example):
Total waste storage Total dilution No. of hrs. volume in cu. ft. + volume in cu. ft to dewater = ------------------------------------------------ Pumping rate in cu. ft/hr.
Dewatering by Tank Wagon. This is usually more expensive and time-consuming than dewatering by irrigation; but it may be justified if lagoon volume is small (less than 75,000 cubic feet) and a large wagon is already available fat east 3000-gallon capacity). Remember, there's twice as much liquid to remove from a lagoon than from a slotted-floor, deep-pit system the waste volume plus an equal volume of dilution water.
To determine amount of time required for dewatering with a tank wagon. use this formula (see worksheet section VIII for example):
Total storage volume in Total dilution volume in
No. of hrs. cuff x 7.5 gals./cu.ft. + Cu ft. x 7.5 gals./cu.ft.
to dewater = --------------------------------------------------------------
Wagon capacity in gals. x No. loads/hr.
Compare this figure with the dewatering time using an irrigation system to get an initial idea of the practicality of tank wagon vs. irrigation dewatering.
Trouble Shooting For Odor Control
Odors are the number one complaint associated with livestock waste lagoons. The cast safeguards against lagoon odors are proper Start-up and careful attention to the addition of dilution water. Some odors can be expected from any anaerobic lagoon, both during the start-up period and for 2-3 weeks every spring and fall as thermal currents in the lagoon carry decomposing waste to the surface. However, a prolonged period of severe odors is usually a sign that something is seriously wrong with the way the lagoon is being operated.
Here are some suggestions for diagnosing and correcting odor problems from an anaerobic waste lagoon system.
1. Be certain of the cause before attempting temporary or permanent solutions. The first thing to do is recalculate the organic loading rate (worksheet sections I and II). Has it changed since the structure was first designed. This is often the case if a producer expands his livestock operation without expanding his waste handling system.
2. Double check your required dilution volume and the schedule for adding dilution water (worksheet section VI). If original dilution volume is found to be inadequate, first dewater to minimum design volume, then refill with water up to half the dilution volume. This dilutes the concentration of waste (or, in effect, decreases organic loading). Even if present dilution volume and schedule check out as adequate, extra water should relieve odor problems. But remember, this is only a temporary solution; the cause of the problem must still be found.
3. Consider as a permanent solution the addition of aeration equipment. Odors will probably intensify for 2-3 weeks after installation, but should then disappear as the bacterial population is converted from anaerobic to aerobic.
4. Chemicals such as lime or nitrates can be added to "sick" lagoons; but this is fairly expensive and usually only temporary. Several enzyme products, deodorants and disinfectants are on the market to aid in odor control. However, we suggest that you first test such products as follows: (a) place the recommended dosage in a 5-gallon mixture of lagoon water and sludge taken from the bottom of the lagoon; (b) set the treated sample next to a similar size container of untreated sample; (c) after the product has had opportunity to "work" (usually a few days), compare its effectiveness with the control sample. Even if it proves satisfactory, compute the cost since some products can be quite expensive at recommended dosages in a large lagoon.
5. Should all attempts at odor control fail, you may have to stop loading the lagoon altogether, pump it down to minimum design volume, then gradually start it up again, using the start-up procedure discussed on page 10.
Example Situation
A swine producer wants to intensity his farrow-to-finish confinement enterprise. He plans for three groups of 50 sows each farrowing twice a year (or 150 sows total and farrowings every other month) and expects an average of 7.5 pigs per litter to reach market weight. That's a typical on-farm inventory of 50 sows and litters in the farrowing house, 375 pigs in the nursery, 375 pigs in the finishing building, and 100 females in gestation quarters.
The present waste handling system is pit-under-slotted-floor, with the manure periodically pumped into a 3000-gallon tanker wagon for field disposal. In his expanded operation, the producer will install a two-stage lagoon (to be dewatered twice a year), with the waste being gravity-transported from the buildings. The proposed lagoon site has no limiting conditions as to depth, but the operator does want to maintain a 100-foot width to facilitate dragline sludge removal, if needed.
What will be the necessary capacity and dimension of each lagoon cell? And what would be his labor commitment if he dewatered using his present tank wagon vs. an irrigation system?
Our Your
Items and calculations example situation
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1. Determine total animal liveweight loading lagoon at any one time* = 20,000 lbs ____________
a. Total wt. of sows + litters: No. litters (50) x avg wt./sow-litter (400 lbs.). = 9,375 lbs ____________
b. Total wt. of nursery pigs: No. pigs (375) x avg. wt./pig (25 lbs.). = 52,500 lbs ____________
c. Total wt. of finishing hogs: No. hogs (375) x avg. wt./hog (142 lbs.). = 35,000 lbs ____________
d. Total wt. of gestating sows: No. cows (100) x avg. wt. cow (350 lbs). = None ____________
e. Total wt. of beef feeders: No. feeders x avg. wt./feeder. = None ____________
f. Total wt. of dairy cows: No. cows x avg. wt./cow. = 116,875 lbs ____________
g. Total liveweight loading lagoon: Sum of Steps 1.a thru 1.f.
2.Determine required capacity of a single-stage lagoon or first cell of
a two-stage lagoon
a. Dewatering frequency: Times per year. = Twice ____________
b. Lagoon volume required per lb. liveweight: From Table 1 for appropriate
dewatering frequency (total volume figure). = 1.25 cu.ft/lb ____________
c. Total lagoon volume required: Step 1.g (116,875 lbs) x Step 2.b (1.25 cu.ft/lb) = 146,094 cu.ft ____________
3. Determine dimensions of a single-stage lagoon or first cell of a
two-stage lagoon**
a. Lagoon depth: Determined by soil type and excavation equipment available. = 15 ft ___________
b. Interior width: Determined by location and sludge removal method. = 100 ft ___________
c. Interior length: From Table 3 for required lagoon volume (Step 2.c) at selected
depth (Step 3.a) and width (Step 3.b). = 216 ft ___________
d. Berm width and freeboard "run": Plan on at least 8 ft. berm for maintenance
equipment plus 5 ft. "run" (width required to obtain 2 ft. freeboard at
2.5:1 side slope) = 13 ft ___________
e. Exterior width (outside of berm to outside of berm): (2 x Step 3.d) + Step 3.b
Example: (2 x 13 ft) + 100 ft. = 26 ft. + 100 ft. = 126 ft ___________
f. Exterior length (outside of berm to outside of berm): (26 x Step 3.d) + Step 3.c
Example.(2 x 13 ft) + 216 ft = 26 ft. + 216 ft = 242 ft ___________
g. Final exterior dimensions (to outside of berms): Steps 3.a, 3.e and 3.f. = 15 ft deep ___________
= 126 ft wide ___________
= 242 ft long ___________
4. Determine required capacity of second cell of a two-stage lagoon
(if used)
a. Lagoon volume required per lb. liveweight: From Table 1 for dewatering = 0.75 cu.ft/lb ___________
frequency recorded in Step 2.a (total volume figure).
b. Total lagoon volume required: Step 1.g (116,875 lbs) x Step 4.a (0.75 cu/ft/lb) = 87,656 cu.ft ____________
5. Determine dimensions of second cell of a two-stage lagoon (if used)
a. Lagoon depth: 6-10 feet recommended (see Table 4) = 10 ft ____________
b. Interior width: Determined by location. = 100 ft ____________
c. Interior length: From Table3 for required lagoon volume (Step 4.b) at selected = 173 ft ____________
depth (Step 5.a) and width (Step 5.b).
d. Berm width and freeboard "run": Same as Step 3.d = 13 ft ____________
e. Exterior width (outside of berm to outside of berm): (2 x Step 5.d) + Step 5.b = 126 ft ____________
Example: (2 x 13 ft) + 100 ft = 26 ft. + 100 ft
f. Exterior length (outside of berm to outside of berm): (2 x Step 5.d) + Step 5.c. = 199 ft ___________
Example: (2 x 13 ft) + 173 ft. = 26 + 173 ft.
g. Final exterior dimensions (to outside of berms): Steps 5.a, 5.e and 5.f. = 10 ft deep ___________
= 126 ft wide ___________
= 199 ft long ___________
6. Determine volume of effluent to be pumped out at each dewatering.
a. Lagoon storage volume per lb. liveweight: From Table 1. = .2 cu.ft/lb ___________
b. Lagoon dilution volume per lb. liveweight: Same as storage volume = .2 cu.ft/lb ___________
(Step 6.a).
c. Per-lb. Liveweight volume to be pumped: Step 6.a (.2 cu.ft.) +
Step 6.b (.2 cu.ft.) = .4 cu.ft/lb ___________
d. Total volume to be pumped out at each dewatering: Step 1.g 116,875 lbs.)
x Step 6.c (.4 cu.ft.). = 46,750 cu.ft ___________
7. Determine time required to dewater by irrigation.
a. Irrigation pump capacity in gals. per min.: = 300 gpm ___________
b. Pumping rate in cu ft. per hr.: [Step 7.a (300 gal/min.) x 60 min./hr.] ÷
7.5 gals/cu.ft = 2400 cu ft/hr ___________
c. No. of hrs. to dewater: Step 6.d (46,750 cu ft.) ÷ Step 7.b (2400 cu.ft/hr) = 19.5 hrs ___________
8. Determine time required to dewater by tanker wagon
a. Tanker wagon capacity in gals.: See discussion on page 11. = 3000 gals ___________
b. Wagon capacity in cu.ft.: Step 8.a (3000 gals.) ÷ 7.5 gals./cu.ft. = 400 cu.ft ___________
c. No. of loads hauled per hr.: From operator experience (usually 2-4). = 3/hrs ___________
d. Volume of effluent hauled per hr.: Step 8.b (400 cu.ft.) x 8.c (3 loads). = 1200 cu ft/hr ___________
e. No. of hrs. to dewater: Step 6.d (46,750 cu.ft) ÷ Step 8.d (1200 cu.ft./hr) = 39 hr. ___________
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* If actual animal lveweights are not known, use the following
estimated weight per animal; sow and litter, 400 lbs; nursery pig 25
lbs; finishing hog, 140 lbs; gestating sow, 350 lbs, beef feeder, 900
lbs; and dairy cow 1200 lbs.
** Lagoon dimensions figures in Table 3 assume 2.5:1 interior side
slope ratio (horizontal distance to rise or fall) and include 2 feet
of freeboard in lagoon depth.
Following are guidelines to help insure adequate design, proper construction, successful operation and problem-free dewatering of a livestock waste lagoon. Don't take short cuts; in the long run, they're not!
State and Federal Agencies
1. County Cooperative Extension Service Offices. Extension livestock and management agents (initial questions).
2. Purdue University Extension Specialists at West Lafayette: Agricultural engineers D.D. Jones and W.H. Friday (lagoon design and irrigation systems); agronomists J.E. Yahner and J.V. Mannering (soils information); and animal scientist A.L. Sutton (waste composition and application rates.)
3. Indiana State Board of Health: Agricultural Waste Disposal Section, 1330 W. Michigan St., Indianapolis 46206 (application for construction of waste facilities).
4. County Soil Conservation Service Offices (USDA). District conservationists (lagoon design, site selection and soils information).
Related Extension Publications
"Solid Waste Handling for
Dairy Operations" ID-122
"Animal Manure as a Plant Nutrient Resource" ID-101
The following Midwest Plan Service publications are available only from the Farm Building Plan Service, Agricultural Engineering Building, Purdue University, West Lafayette, Indiana 47907:
RR 9/80
Cooperative Extension work in Agriculture and Home Economics, state of Indiana, Purdue university, and U.S. Department of Agriculture cooperating; H. A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Cooperative Extension Service of Purdue university is an affirmative action/equal opportunity institution.
Reviewed September 1999