September 5, 2017 at 3:32 p.m.
On the pontoon
Like many dairies, our manure system has evolved with major changes made about every six years. In 2001, when we built the original 400-cow site, our plan was to bed cows with new sand and skid loader scrape the four pens outside into a 100-by 200-foot concrete holding area with the liquids gravity flowing into a one million gallon earthen lagoon. The sand bedding was great, but winter was brutal trying to push the manure out the northwest-facing door. For five long winter months the manure was a huge non moving frozen ice block in the cement pond as it was affectionately called. We tried and wore out every imaginable kind of manure spreader trying to winter haul that sand laden manure. After a few years, we threw up the white flag and knew we had to change.
At that time, we were considering adding a second freestall barn if we could solve the manure problem. We had heard about sand recycling lanes in conjunction with flush flume barns so we toured a few and hired a contractor. We built a new flush flume 500 freestall barn and retrofitted our older barn with a flume. Our cement pond was in a perfect place to make it into a sand settling lane and also a recycled sand storage area. We added a five million gallon earthen lagoon with a cistern style pumping station on the far end. That 30-horsepower submersible pump took lagoon water from the bottom side of the lagoon and pumped it through an eight inch line 1,300 feet back into the continuous flume running under the manure traps in the freestall barns. In theory, the manure, sand and water were supposed to stay in a suspended slurry until it came out of the 24-inch flume and landed in the 8-foot sand lane where the sand could settle out to be reused. The manure and water gravity flowed on to the lagoons.
We used that system from 2007 to 2012, but it too had many problems. The eight inch line was too small, and drawing gray water from the lower part of the lagoon caused it to be too thick, which in turn caused sand to settle out in the flume before it reached the sand lane. This in turn caused a flooded freestall barn at times, which is equivalent to sewage in a flooded basement only way bigger.
Hence, when we doubled the cross ventilated barn last summer, we knew we had to improve the manure system. We made the 8-inch line and submersible pump a backup system, and dug in a new 12-inch 800-foot line fed by a floating 30 horsepower pump located in the big new lagoon. The floating pump draws gray water from 18 inches below the surface instead of the bottom of the lagoon. Instead of a thick slurry, it really is just gray water that greatly improves our GPM thus keeping our flume clean. In turn, this creates much cleaner recycled sand to bed our cows with.
Yes, the shaft did break after six months, but we know what caused it and can prevent it in the future. Yes, there will be other problems with the system, but overall it's working great. Yes, this article may have seemed long and boring to most people, except those who have fixed barn cleaners, piston pumps, separators and all other manure pumps known to man. Yes, in five years we will probably change something again.