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How To Handle Seepage From Farm Silos

Factsheet - ISSN 1198-712X   -   Copyright Queen's Printer for Ontario
Agdex#: 732
Publication Date: November 2004
Order#: 04-031
Last Reviewed: November 2004
History: Replaces OMAFRA Factsheet, How to Handle Seepage from Farm Silos, Order Number 95-043
Written by: Steve Clarke - Engineer, Energy and Crop Systems/OMAFRA; Robert P. Stone - Engineer, Soil Management/OMAFRA.

Table of Contents

  1. Introduction
  2. Why Silo Seepage Is An Environmental Problem
  3. Rate and Volume of Seepage Flow
  4. Managing Silo Seepage and Precipitation Runoff
  5. Disposal of Seepage
  6. Site Location for Seepage Collection Tanks
  7. Sizing of Small Seepage Tanks

Introduction

Silage seepage presents two concerns for the agricultural industry - pollution of land and water may result from silage seepage, and the silage juices cause corrosion and deterioration of the silo. When silage is harvested and stored at low moisture contents less than 70% for horizontal silos and 60% for tower silos, there is minimal corrosion and pollution threat. Above this moisture level significant flow of silage juices (or seepage) from silos may occur (Table 1 and Figure 1).

Wet weather can force farmers into harvesting wet silage with resulting silage seepage, even when the greatest of care is taken.

Most of the environmental problems associated with silage/haylage seepage on farms result from improper or inadequate collection and retention of the seepage draining from the silos. An adequate collection and storage/treatment system is essential.

See Table 2 for information on the acids in silage seepage that cause silo corrosion. Detailed information on silo corrosion is available in OMAFRA Factsheets Order No. 90-236, Concrete Tower Silo Maintenance and Repair, and Order No. 08-057, Deterioration of Concrete Tower Silos.

Why Silo Seepage Is An Environmental Problem

During 1983 farmers in Ontario made 4.1 million tons of corn fodder, producing in the process approximately 20 million litres of silage seepage effluent. This effluent can be the most polluting organic surface discharge that occurs from farming. The potential oxygen-consuming capacity of effluent is measured by the biochemical oxygen demand test (BOD). Silage effluent in an undiluted form has extremely high BOD values, ranging from 12,000-90,000 mg/L (Table 3), which is approximately 60-450 times stronger than domestic sanitary sewage. A significant discharge of effluent into a watercourse can remove so much oxygen that fish and other aquatic creatures die immediately. For example, as little as one gallon of silage effluent can lower the oxygen content of 10,000 gallons of river water to a critical level with respect to fish survival.

Table 1. Tower Silo - Maximum Moisture Content to Minimize Seepage, Whole-Plant Silages
Silo Size
(ft.)
Max. Moisture Content
(%)
12 x 40 72
14 x 50 70
16 x 60 68
18 x 65 67
20 x 70 66
24 x 85 63

30 x 110

60

 

Horizontal silo — seepage production based on silage moisture content.

Figure 1. Horizontal silo - seepage production based on silage moisture content.

There have been a number of fish kills from silage seepage in Pennsylvania, New York and Ontario. There are cases of silage seepage contaminating wells and ditches each year in Ontario and the United States.


Table 2. Aggressive Constituents of Silage Seepage

Lactic Acid: 4%-6%

Acetic Acid: 1%-2%

Butyric Acid: normally less than 1%

Acidity: 4

pH: 3.5-5.5


With respect to ground water quality, silage leachate contains nutrients, acids, minerals and bacteria. Nitrate-nitrogen is the most significant ground water contaminant from this group. The main constituents of silage seepage are listed in Table 3.

Rate and Volume of Seepage Flow

The addition of acid additives to silage combined with short chop silage lengths results in a higher initial rate of seepage flow. The greatest percentage of silage seepage is produced within 5 to 10 days of storage loading. The remaining seepage is produced within the next 30 days. The volumes produced are dependent on the vertical pressure in the silo and the initial moisture content of the crop (Figure 1). Seepage flow out of the silo will be greatest during the first month of storage and then taper off in silos with good internal drainage, i.e. network of floor drains to carry out leachate. Where internal drainage of the silo is poor, flow will occur throughout the total storage period as the silo is being emptied. Rainwater on uncovered silage can produce additional effluent.

For horizontal silos, the rain runoff or snow melt from the floor area inside the storage adds more effluent to the system. The highly polluted base flow will be augmented on occasion by the diluted flow from rainstorms and snowmelt. The first flush of rainwater runoff from the storage will contain higher levels of pollutants. It is important that all the base flow from the silo along with the first flush of precipitation runoff be collected and stored since this material is highly contaminated.

Storage and Treatment of Silage Seepage

The seepage and runoff may be stored in a small storage at the silo location and transferred to an outdoor liquid manure or runoff storage on the farm. Contain silage leachate only in an outdoor storage, because dangerous gases may be produced when the effluent and manure are mixed. Where outdoor liquid manure or runoff storages are not currently available on the farm, provide a separate storage to contain 240 days of seepage plus runoff material. During the cropping season this contaminated material can be spread regularly on land similar to manure application. If seepage is being applied to the land, the amount of material being applied needs to be accounted for in the Nutrient Management Plan.

Another means of handling and treating the effluent involves collecting and storing the low flow rates of concentrated leachate from the silo in a storage tank. The dilute high flow rates of material will overtop the collection area and flow to an approved vegetated filter strip (Figure 2).

Have a qualified person design a vegetated filter strip. The design must receive approval under the Ontario Water Resources Act through the Ministry of the Environment.

Table 3. Constituents of Silage Seepage
Constituents Silage Seepage
(typical)
Dairy Manure Liquid
(typical)
Dry Matter 5% (2%-10%) 5%
Total Nitrogen 1,500-4,400 mg/L 2,600 mg/L
Phosphorus 300-600 mg/L 1,100 mg/L
Potassium 3,400-5,200 mg/L 2500 mg/L
pH 4.0 (3.6-5.5) 7.4
Biochemical Oxygen Demand 12,000-90,000 mg/L 5,000-10,000 mg/L

Source: Cornell University 1994 and OMAFRA

Horizontal silo front flow seepage system – diluted liquid to vegetated filter strip.

Figure 2. Horizontal silo front flow seepage system - diluted liquid to vegetated filter strip.

Reduction of Seepage

  • Harvest silage/haylage at low moisture:
    • < 65% moisture content for tower silos less than 40 ft. deep
    • < 60 % moisture content for tower silos over 40 ft. deep
    • < 70% for horizontal silos
  • Planting shorter season varieties of corn will result in a drier crop; therefore, lower seepage production.

Bunker Silo Sealing Systems

  • Reduce silage infiltration by air and water.
  • Traditionally, a sealing system consists of a layer of white or black plastic used as a cover and seal. Old tires are placed edge to edge over the surface of this plastic to help in sealing.

New Silo Sealing System, "no tires used"

  • Traditional plastic sheeting is covered with an additional cover. Instead of tires, sausage-bags, which are filled with sand or gravel, anchor the cover in place (Figure 3). The advantages of this system are the added protection, improved sealing, flexibility, and ease of installation and storage of the sandbags.
    • A polyethylene sleeve holds together several of the sausage-bags across the width of a silo. This product reduces the chance of air infiltration between the sausage bags. Figure 4 shows sausage bag placement.
    • The sausage bags can be used directly on the silo plastic. This reduces the cost, and replaces the use of tires. This is a good solution if birds or animals tear the plastic seal.

Picture of a tarpaulin and sausage bag system covering silage for protection.

Figure 3. Tarpaulin and sausage bag system for silage protection.

Figure 4. Sausage bag placement.

Figure 4. Sausage bag placement.

Adding absorbents designed to take up excess moisture will result in very low or no seepage production. Useable materials include oatmeal, dried sugar beet pulp, dried corncobs, ground corn and hay cubes. To be effective, enough material must be added to absorb the anticipated seepage.

On many occasions it may not be possible to wilt the forage adequately or harvest at the desired dry matter content. If the forage is too wet, then seepage is likely. Absorbent materials can be added to "absorb" this seepage. Table 4 lists the water holding capacity of various materials.

Table 4. Water Holding Capacity of Various Materials
Material1 Pounds of Water per
100 lbs of Material
Ground corn grain 58*
Ground oats 69*
Ground wheat 61*
Corn cob: Coarse grind (1/2 inch) 143*
Corn cob: Medium to find grind 192*
Corn cob: Fine grind (1/16 inch) 192*
Sugar beet pulp 248**

Alfalfa hay

194**

Mixed grass hay

195**

Oat straw

218**

1. Materials are on an air-dry basis
* 10% moisture content
** 12% moisture content

Source: University of Minnesota (1980)

Managing Silo Seepage and Precipitation Runoff

  • Cover the silos - this prevents precipitation from entering and leaching through the silage/haylage.
  • Divert all surface water away from the silo site.
  • For new silos install a seepage collection and storage system as shown in Figure 2, Figure 5 or Figure 6.
  • Inspect the interior silo surface each time the silo is empty for signs of corrosion. Whenever corrosion is severe, recoat the inside of the silos.
  • For existing horizontal silos, place a 4 in. tile drain on the floor where the wall meets the silo floor (Option A, Figure 7), or for new silos form holes in the wall to drain silo seepage to an outside drain (Option B, Figure 7. Caution: Provide protection of steel from silage acids with adequate concrete cover (i.e. min. 3 in.)
  • For existing or new horizontal silos with good floor drainage to the front of the silo, a catch basin that collects seepage and drains to a long-term storage tank will be suitable (Figure 8 and Figure 9). Flow will occur throughout the total storage period as the silo is emptied. Diluted flow can by-pass the storage tank and overflow to the approved vegetated filter strip (Figure 2).

Tower silo seepage storage system.

Figure 5. Tower silo seepage storage system.

Figure 6. Horizontal silo seepage floor drain collection system.

Figure 6. Horizontal silo seepage floor drain collection system.

Notes for Figure 6:

  • Cross drains 3 in. x 3 in. on 20 ft. spacing. Filled with 7/8 in. clear stone. (Drain to pick up seepage and first flush of rain runoff.)
  • Header drain 4 in. x 4 in. to drain cross drains to storage tank.
  • Rain runoff from top of storage may be considered as clean water and will not reach the collection system.
  • Rain runoff from inside of storage should be collected, stored and spread on cropland.
  • Diluted rain runoff may be treated by an approved vegetated filter strip.

Figure 7. Outside drain collection system for existing horizontal silo.

Figure 7. Outside drain collection system for existing horizontal silo.

Notes for Figure 7:

(A) 4" diameter tile drains placed on silo floor.

(B) Holes in silo walls to an exterior covered drain. Rain runoff from inside storage should be collected, stored and spread on cropland.

Diluted rain runoff may be treated by an approved vegetated filter strip.

Figure 8. Low flow collection system. (Source AEM)

Figure 8. Low flow collection system. (Source AEM)

Picture showing a low flow collection system.

Figure 9. Low flow collection system.

Caution: Never mix silage effluent in enclosed tanks, especially tanks within barns because silage effluent mixed with manure slurry will accelerate the release of hydrogen sulphide gas. Add seepage only to uncovered outdoor storages.

Disposal of Seepage

Dilute the concentrated seepage with the same amount of water (1:1) and spread this material on land using liquid manure spreading guidelines. Seepage is a nutrient; therefore, the amount of seepage being applied needs to be accounted for in the Nutrient Management Plan. Seepage also may be used as a supplementary feed. Fresh effluent may be fed to pigs and cattle or one may feed "stored effluent" if collected in closed drains and stored in airtight containers. High potassium and nitrate levels can cause problems, therefore, feed with expert advice only. Some research in Europe indicates that feeding of silage seepage to dairy cows increased milk yields, protein levels and fat levels. Treat dilute material with an approved vegetated filter strip.

Site Location for Seepage Collection Tanks

The Environmental Farm Plan recommends, as a good management practice, locating seepage collection tanks at a separation distance of 200 ft or greater from surface water, i.e. streams, ditches, ponds or tile inlets, and separation distances between seepage tanks and wells at 76 ft or greater for a drilled well and 151 ft or greater for a bored/dug well. Minimum separation distances of 50 ft to a drilled well and 100 ft to a dug/bored well are stipulated under legislation. Locate storage sites for bagged, wrapped or tubed haylage (baylage) at least 30 ft. from surface water sources and field drainage tiles to reduce the risk of contamination.

Sizing of Small Seepage Tanks

A. For Horizontal Silos

  • If crop is stored > 70% moisture, size seepage storage for 100 ft3/100 tons of crop stored.
  • If crop is stored at/or below 70% moisture, use 50 ft3/100 tons of crop stored.
  • The above design criteria will give, in most cases, a minimum of 2 days of storage for the seepage material. With very low moisture crops (< 70% moisture), up to one year of storage can be provided with this design, when no rainwater is collected.
  • Rainfall Storage: Size for minimum of 1 in. or 0.083 ft. rain over entire silage storage area flowing to leachate storage in any one day. This material can be transferred to an outside liquid manure or runoff storage. If there is no liquid storage on farm, consider building the leachate storage to contain runoff and seepage for a minimum storage period of 240 days. Another option is to treat this dilute liquid on an approved vegetated filter strip.

Example 1:

Size a storage to contain seepage and runoff from a 40 x 100 x 12 ft. horizontal silo. Apron area is 40 x 20 ft. Crop moisture content is 75%. See Table 5.

Storage Capacity (T)

T70 = 1,080 tons (from Table 5)
         (storage capacity at 70% moisture)

T75 = 0.3 (T70)/(1-M) (storage capacity at 75% moisture)
      = 0.3 (1080)/(1.75)
      = 1,296 tons

Seepage Storage Volume

Seepage = 100 ft3/100 tons x1,296 tons
              = 1,296 ft.3ainfall Storage Volume

Rainfall Storage Volume

= (.083 ft.) x (area of silo + apron area)
= (.083 ft.) x 40 x 100 + 40 x 20) sq. ft.
= (.083 ft.) x (4,800 sq. ft.)
= 398 ft.3

Required Storage Size

= 1,296 + 398 ft.3
= 1,694 ft.3

Seepage and Precipitation Storage Size* (1,694 ft.3)

Use Table 7 to find the dimensions of the required storage capacity = width x length x height
1,764 = 14 x 14 x 9 ft.
2,156 ft.3 = 14 x 14 x 11 ft. (allows 2 ft. of depth for freeboard)

* Transfer leachate material from this storage to permanent outside liquid manure or runoff storage. During cropping season this material can be land spread on a regular basis.

B. For Tower Silos

  • If crop is stored > 70% moisture, size seepage storage for 100 ft3/100 tons of crop stored.
  • If crop is stored at/or below 70% moisture, use 50 ft3/100 tons of crop stored.
  • The above design criteria will give, in most cases, a minimum of 2 days of storage for the seepage material. Up to one year of storage can be provided with very low moisture crops, i.e. < 60% moisture.
  • Tower silo is covered with roof to keep out rain.

Example 2:

Size seepage tank based on the following criteria:

  1. 20 x 70 ft. tower concrete silo
  2. Alfalfa silage at 70% moisture
  3. For capacity see Table 6 in OMAFRA Factsheet, Tower Silo Capacities, Order No. 88-033.

Storage capacity = 703 tons

Storage capacity = 703 tons

Required seepage storage size

= 50 ft3/100 tons x 703 tons
= 0.5 x 703 = 352 ft3

Storage size (352 ft.3) = width x length x height

Use Table 7 to find the dimensions of the required storage capacity.

384 = 8 x 8 x 6 ft. > 352 okay
512 = 8 x 8 x 8 ft. (allows 2 ft. of depth for freeboard)


Table 5. Capacities for Common Horizontal Silo Sizes (Capacity is in tons for a grass or corn silage density of 45 pounds per cubic ft. at 70% moisture)

The following tables list the approximate wet tons capacity for a number of common silo sizes. The tables take into account a 1:2 sloping front face. Widths given are inside to inside and do not include space taken up by posts and planking. When using these tables, calculate the daily feed removal to ensure enough feed is removed to prevent spoilage. For capacity in Tonnes, multiply figures shown by 0.91.

Table 5a. Capacities for Common Horizontal Silo Sizes (Silo Length 100-160 ft)
(Capacity is in tons for a grass or corn silage density of 45 pounds per cubic ft. at 70% moisture)
Average Silage Density (lbs/cu ft) Silo Height (ft) Silo Width (ft) Removal Rate (tons/day) Silo Capacity (tons)
Silo Length (ft)
4"
/day
6"
/day
12"
/day
100 110 120 130 140 150 160
45 8 20 1.2 1.8 3.6 360 396 432 468 504 540 576
45 8 24 1.4 2.2 4.3 432 475 518 562 605 648 691
45 8 30 1.8 2.7 5.4 540 594 648 702 756 810 864
45 8 40 2.4 3.6 7.2 720 792 864 936 1008 1080 1152
45 8 50 3.0 4.5 9.0 900 990 1080 1170 1260 1350 1440
45 8 60 3.6 5.4 10.8 1080 1188 1296 1404 1512 1620 1728
45 10 20 1.5 2.3 4.5 450 495 540 585 630 675 720
45 10 24 1.8 2.7 5.4 540 594 648 702 756 810 864
45 10 30 2.3 3.4 6.8 675 743 810 878 945 1013 1080
45 10 40 3.0 4.5 9.0 900 990 1080 1170 1260 1350 1440
45 10 50 3.8 5.6 11.3 1125 1238 1350 1463 1575 1688 1800
45 10 60 4.5 6.8 13.5 1350 1485 1620 1755 1890 2025 2160
45 12 20 1.8 2.7 5.4 540 594 648 702 756 810 864
45 12 24 2.2 3.2 6.5 648 713 778 842 907 972 1037
45 12 30 2.7 4.1 8.1 810 891 972 1053 1134 1215 1296
45 12 40 3.6 5.4 10.8 1080 1188 1296 1404 1512 1620 1728
45 12 50 4.5 6.8 13.5 1350 1485 1620 1755 1890 2025 2160
45 12 60 5.4 8.1 16.2 1620 1782 1944 2106 2268 2430 2592
45 14 20 2.1 3.2 6.3 630 693 756 819 882 945 1008
45 14 24 2.5 3.8 7.6 756 832 907 983 1058 1134 1210
45 14 30 3.2 4.7 9.5 945 1040 1134 1229 1323 1418 1512
45 14 40 4.2 6.3 12.6 1260 1386 1512 1638 1764 1890 2016
45 14 50 5.3 7.9 15.8 1575 1733 1890 2048 2205 2363 2520
45 14 60 6.3 9.5 18.9 1890 2079 2268 2457 2646 2835 3024
45 16 20 2.4 3.6 7.2 720 792 864 936 1008 1080 1152
45 16 24 2.9 4.3 8.6 864 950 1037 1123 1210 1296 1382
45 16 30 3.6 5.4 10.8 1080 1188 1296 1404 1512 1620 1728
45 16 40 4.8 7.2 14.4 1440 1584 1728 1872 2016 2160 2304
45 16 50 6.0 9.0 18.0 1800 1980 2160 2340 2520 2700 2880
45 16 60 7.2 10.8 21.6 2160 2376 2592 2808 3024 3240 3456
45 18 20 2.7 4.1 8.1 810 891 972 1053 1134 1215 1296
45 18 24 3.2 4.9 9.7 972 1069 1166 1264 1361 1458 1555
45 18 30 4.1 6.1 12.2 1215 1337 1458 1580 1701 1823 1944
45 18 40 5.4 8.1 16.2 1620 1782 1944 2106 2268 2430 2592
45 18 50 6.8 10.1 20.3 2025 2228 2430 2633 2835 3038 3240
45 18 60 8.1 12.2 24.3 2430 2673 2916 3159 3402 3645 3888

 

Table 5b. Capacities for Common Horizontal Silo Sizes (Silo Length 170-230 ft)
(Capacity is in tons for a grass or corn silage density of 45 pounds per cubic ft. at 70% moisture)
Average Silage Density (lbs/cu ft) Silo Height (ft) Silo Width (ft) Removal Rate (tons/day)

Silo Capacity (tons)
Silo Length (ft)

4"
/day
6"
/day
12"
/day
170 180 190 200 210 220 230
45 8 20 1.2 1.8 3.6 612 648 684 720 756 792 828
45 8 24 1.4 2.2 4.3 734 778 821 864 907 950 994
45 8 30 1.8 2.7 5.4 918 972 1026 1080 1134 1188 1242
45 8 40 2.4 3.6 7.2 1224 1296 1368 1440 1512 1584 1656
45 8 50 3.0 4.5 9.0 1530 1620 1710 1800 1890 1980 2070
45 8 60 3.6 5.4 10.8 1836 1944 2052 2160 2268 2376 2484
45 10 20 1.5 2.3 4.5 765 810 855 900 945 990 1035
45 10 24 1.8 2.7 5.4 918 972 1026 1080 1134 1188 1242
45 10 30 2.3 3.4 6.8 1148 1215 1283 1350 1418 1485 1553
45 10 40 3.0 4.5 9.0 1530 1620 1710 1800 1890 1980 2070
45 10 50 3.8 5.6 11.3 1913 2025 2138 2250 2363 2475 2588
45 10 60 4.5 6.8 13.5 2295 2430 2565 2700 2835 2970 3105
45 12 20 1.8 2.7 5.4 918 972 1026 1080 1134 1188 1242
45 12 24 2.2 3.2 6.5 1102 1166 1231 1296 1361 1426 1490
45 12 30 2.7 4.1 8.1 1377 1458 1539 1620 1701 1782 1863
45 12 40 3.6 5.4 10.8 1836 1944 2052 2160 2268 2376 2484
45 12 50 4.5 6.8 13.5 2295 2430 2565 2700 2835 2970 3105
45 12 60 5.4 8.1 16.2 2754 2916 3078 3240 3402 3564 3726
45 14 20 2.1 3.2 6.3 1071 1134 1197 1260 1323 1386 1449
45 14 24 2.5 3.8 7.6 1285 1361 1436 1512 1588 1663 1739
45 14 30 3.2 4.7 9.5 1607 1701 1796 1890 1985 2079 2174
45 14 40 4.2 6.3 12.6 2142 2268 2394 2520 2646 2772 2898
45 14 50 5.3 7.9 15.8 2678 2835 2993 3150 3308 3465 3623
45 14 60 6.3 9.5 18.9 3213 3402 3591 3780 3969 4158 4347
45 16 20 2.4 3.6 7.2 1224 1296 1368 1440 1512 1584 1656
45 16 24 2.9 4.3 8.6 1469 1555 1642 1728 1814 1901 1987
45 16 30 3.6 5.4 10.8 1836 1944 2052 2160 2268 2376 2484
45 16 40 4.8 7.2 14.4 2448 2592 2736 2880 3024 3168 3312
45 16 50 6.0 9.0 18.0 3060 3240 3420 3600 3780 3960 4140
45 16 60 7.2 10.8 21.6 3672 3888 4104 4320 4536 4752 4968
45 18 20 2.7 4.1 8.1 1377 1458 1539 1620 1701 1782 1863
45 18 24 3.2 4.9 9.7 1652 1750 1847 1944 2041 2138 2236
45 18 30 4.1 6.1 12.2 2066 2187 2309 2430 2552 2673 2795
45 18 40 5.4 8.1 16.2 2754 2916 3078 3240 3402 3564 3726
45 18 50 6.8 10.1 20.3 3443 3645 3848 4050 4253 4455 4658
45 18 60 8.1 12.2 24.3 4131 4374 4617 4860 5103 5346 5589

 

Table 5c. Capacities for Common Horizontal Silo Sizes (Silo Length 240-300 ft)
(Capacity is in tons for a grass or corn silage density of 45 pounds per cubic ft. at 70% moisture)
Average Silage Density (lbs/cu ft) Silo Height (ft) Silo Width (ft) Removal Rate (tons/day) Silo Capacity (tons)
Silo Length (ft)
4"
/day
6"
/day
12"
/day
240 250 260 270 280 290 300
45 8 20 1.2 1.8 3.6 864 900 936 972 1008 1044 1080
45 8 24 1.4 2.2 4.3 1037 1080 1123 1166 1210 1253 1296
45 8 30 1.8 2.7 5.4 1296 1350 1404 1458 1512 1566 1620
45 8 40 2.4 3.6 7.2 1728 1800 1872 1944 2016 2088 2160
45 8 50 3.0 4.5 9.0 2160 2250 2340 2430 2520 2610 2700
45 8 60 3.6 5.4 10.8 2592 2700 2808 2916 3024 3132 3240
45 10 20 1.5 2.3 4.5 1080 1125 1170 1215 1260 1305 1350
45 10 24 1.8 2.7 5.4 1296 1350 1404 1458 1512 1566 1620
45 10 30 2.3 3.4 6.8 1620 1688 1755 1823 1890 1958 2025
45 10 40 3.0 4.5 9.0 2160 2250 2340 2430 2520 2610 2700
45 10 50 3.8 5.6 11.3 2700 2813 2925 3038 3150 3263 3375
45 10 60 4.5 6.8 13.5 3240 3375 3510 3645 3780 3915 4050
45 12 20 1.8 2.7 5.4 1296 1350 1404 1458 1512 1566 1620
45 12 24 2.2 3.2 6.5 1555 1620 1685 1750 1814 1879 1944
45 12 30 2.7 4.1 8.1 1944 2025 2106 2187 2268 2349 2430
45 12 40 3.6 5.4 10.8 2592 2700 2808 2916 3024 3132 3240
45 12 50 4.5 6.8 13.5 3240 3375 3510 3645 3780 3915 4050
45 12 60 5.4 8.1 16.2 3888 4050 4212 4374 4536 4698 4860
45 14 20 2.1 3.2 6.3 1512 1575 1638 1701 1764 1827 1890
45 14 24 2.5 3.8 7.6 1814 1890 1966 2041 2117 2192 2268
45 14 30 3.2 4.7 9.5 2268 2363 2457 2552 2646 2741 2835
45 14 40 4.2 6.3 12.6 3024 3150 3276 3402 3528 3654 3780
45 14 50 5.3 7.9 15.8 3780 3938 4095 4253 4410 4568 4725
45 14 60 6.3 9.5 18.9 4536 4725 4914 5103 5292 5481 5670
45 16 20 2.4 3.6 7.2 1728 1800 1872 1944 2016 2088 2160
45 16 24 2.9 4.3 8.6 2074 2160 2246 2333 2419 2506 2592
45 16 30 3.6 5.4 10.8 2592 2700 2808 2916 3024 3132 3240
45 16 40 4.8 7.2 14.4 3456 3600 3744 3888 4032 4176 4320
45 16 50 6.0 9.0 18.0 4320 4500 4680 4860 5040 5220 5400
45 16 60 7.2 10.8 21.6 5184 5400 5616 5832 6048 6264 6480
45 18 20 2.7 4.1 8.1 1944 2025 2106 2187 2268 2349 2430
45 18 24 3.2 4.9 9.7 2333 2430 2527 2624 2722 2819 2916
45 18 30 4.1 6.1 12.2 2916 3038 3159 3281 3402 3524 3645
45 18 40 5.4 8.1 16.2 3888 4050 4212 4374 4536 4698 4860
45 18 50 6.8 10.1 20.3 4860 5063 5265 5468 5670 5873 6075
45 18 60 8.1 12.2 24.3 5832 6075 6318 6561 6804 7047 7290

The following table lists the approximate wet tons capacity for a number of common silo sizes.


Table 6a. Estimated Silo Capacities for Forages in Concrete Tower Silos
Silo Diameter X Settled Depth (ft.) Alfalfa Silage
(Tons)
40%
m.c.
50%
m.c.
60%
m.c.
70%
m.c.
12 x 30 35 44 57 83
12 x 40 50 62 80 116
12 x 50 63 78 103 150
14 x 40 69 86 113 163
14 x 50 89 111 147 212
14 x 55 99 124 164 237
16 x 50 120 151 199 287
16 x 60 149 186 246 355
16 x 65 162 204 270 389
18 x 50 156 196 260 373
18 x 60 194 243 322 463
18 x 70 232 290 386 554
20 x 60 246 309 409 586
20 x 70 295 371 491 703
20 x 80 345 433 574 821
24 x 60 372 465 615 876
24 x 70 448 562 741 1052
24 x 80 527 660 869 1230
24 x 90 606 759 999 1409
30 x 80 876 1092 1427 1994
30 x 90 1012 1261 1643 2287
30 x 100 1151 1431 1861 2581
30 x 110 1290 1603 2080 2875

Source: OMAFRA Factsheet Tower Silo Capacities, Order No. 88-033.

Table 6b. Estimated Silo Capacities for Forages in Concrete Tower Silos

Silo Diameter X Settled Depth (ft.)

Corn Silage
(Tons)
55% m.c. 60% m.c. 65% m.c. 70% m.c.
12 x 30 47 54 62 74
12 x 40 66 75 87 102
12 x 50 85 97 111 132
14 x 40 92 106 121 143
14 x 50 121 136 157 185
14 x 55 134 153 175 206
16 x 50 163 184 210 246
16 x 60 200 227 259 303
16 x 65 220 248 284 330
18 x 50 210 238 272 317
18 x 60 261 293 334 388
18 x 70 311 349 397 461
20 x 60 328 369 419 486
20 x 70 393 439 498 576
20 x 80 457 510 579 668
24 x 60 486 543 616 712
24 x 70 582 649 734 844
24 x 80 678 754 850 977
24 x 90 774 860 968 1110
30 x 80 1088 1280 1477 1628
30 x 90 1242 1475 1702 1877
30 x 100 1397 1672 1929 2127
30 x 110 1552 1871 2158 2382

Source: OMAFRA Factsheet Tower Silo Capacities, Order No. 88-033.

 

Table 7. Seepage and Precipitation Storage Sizes (ft.3)

Width Length
(ft.)

Height (ft.)
1 2 3 4 5 6 7 8 9 10 11 12
5 x 5 25 50 75 100 125 150 175 200 225 250 275 300
6 x 6 36 72 108 144 180 216 252 288 324 360 396 432
7 x 7 49 98 147 196 245 294 343 392 441 490 539 588
8 x 8 64 128 192 256 320 384 448 512 576 640 704 768
9 x 9 81 162 243 324 405 486 567 648 729 810 891 972
10 x 10 100 200 300 400 500 600 700 800 900 1000 1100 1200
11 x 11 121 242 363 484 605 726 847 968 1089 1210 1331 1452
12 x 12 144 288 432 576 720 864 1008 1152 1296 1440 1584 1728
13 x 13 169 338 507 676 845 1014 1183 1352 1521 1690 1859 2028
14 x 14 196 392 588 784 980 1176 1372 1568 1764 1960 2156 2352
15 x 15 225 450 675 900 1125 1350 1575 1800 2025 2250 2475 2700
16 x 16 256 512 768 1024 1280 1536 1792 2048 2304 2560 2816 3072
17 x 17 289 578 867 1156 1445 1734 2023 2312 2601 2890 3179 3468
18 x 18 324 648 972 1296 1620 1944 2268 2592 2916 3240 3564 3888
19 x 19 361 722 1083 1444 1805 2166 2527 2888 3249 3610 3971 4332
20 x 20 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800
21 x 21 441 882 1323 1764 2205 2646 3087 3528 3969 4410 4851 5292
22 x 22 484 968 1452 1936 2420 2904 3388 3872 4356 4840 5324 5808
23 x 23 529 1058 1587 2116 2645 3174 3703 4232 4761 5290 5819 6348
24 x 24 576 1152 1728 2304 2880 3456 4032 4608 5184 5760 6336 6912
25 x 25 625 1250 1875 2500 3125 3750 4375 5000 5625 6250 6875 7500

 

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