North
West New York
Dairy, Livestock & Field Crops
Team
Dairy, Livestock & Field Crops
Team
Agfocus article
Question of the Month: What information you do have on building asphalt-bottomed forage silo bunks? And how much do they cost?
Answer: There is minimal information in print on asphalt-bottomed bunks; therefore, I asked Ev Thomas, Miner Institute, Curt Gooch, PRO-DAIRY, and area producers for their expertise and experiences.
All stressed that a sound, well-drained base is essential. Depending on the type of site, the use of bank-run gravel or crusher run crushed stone should be used for a base. The base should be between 6” and 12" deep, depending on the site and material. Drainage should be placed inside and outside the footing to keep water from getting under the asphalt. In addition, most sites used approximately 4” to 6" of asphalt, which is 3-5" of fine material, and then about 1" of very fine material. The top material is similar to a sealer and Miner Institute used the brand called Armor Coat.
The asphalt should be compacted at least twice, once with a heavy or vibrating roller and the second time with a finishing roller to remove ripples. Ev Thomas stresses that the people “who roll out driveways on weekends ARE NOT who you should hire to do this job.” Both suggested that a road-quality asphalt contractor is the one to hire. A twenty-ton roller is needed for adequate compaction, not the typical driveway roller!
Another suggestion is that all working edges should be protected with a concrete edging of at least 3” to 6” to decrease the crumbling of the edge. Asphalt costs less than or about the same as concrete, depending on how much base you need. One producer estimated his bunk cost about $2.00 per square foot.
Therefore, the site selection is very important in calculating the cost of the bunk. NRCS can help you assess the site and suggest the correct type of design and remember that it is important to plan to collect the bunk seepage. Seepage must be collected and land-spread or treated according to NRCS specifications as part of a CAFO (Concentrated Animal Feeding Operation) or AEM (Ag
Environmental Management) plan.
For more information or details on construction, contact Jerry.