North Dakota State University
NDSU Extension Service

No. 179, October 1999
http://www.ext.nodak.edu/extnews/snouts

This is the final issue of Water Spouts for 1999.
If you have access to the Internet, you can obtain copies out
past issues of Water Spouts at this address:
www.ext.nodak.edu/extnews/snouts/.
The next issue of Water Spouts will be in April of 2000.

Mark Your Calendar for these Irrigation Workshops

The workshops in Bismarck will be held in conjunction with the annual North Dakota Water Users Convention. All workshops will start about 9 a.m. and finish around 4:00 p.m. An application for Certified Crop Advisor (CCA) CEU's will be made for each workshop. The number for CEUs will be announced at the workshops.

A mail announcement with more details will be sent to you in November.

Tom Scherer, (701) 231-7239
Extension Agricultural Engineer
tscherer@ndsuext.nodak.edu

Park Your Center Pivot in the Right Direction

When it comes to wind and sleet, the center pivot is a rather fragile machine. Center pivots that have no nearby protection such as windbreaks should be parked for the winter pointing to the northwest or southeast, not to the northeast or southwest (Figure 1). The ice storm blizzard of April 5-8, 1997 damaged many center pivots that were parked pointing in the wrong direction.

Figure 1. For the winter, point your pivot towards the
northwest or southwest, not the northeast or southwest.

From October to April the worst storms and highest winds come from the northwest. Properly parking a pivot will present the smallest surface area to the wind. Exceptions to the parking direction are center pivots that border windbreaks. In this case, the pivot should be parked next to the windbreak.

While you are parking your pivot for the winter, do the following checks, they could save you some work in the spring.

1. Inspect the sprinklers. Either note the location of or repair any sprinklers that are broken or were observed to not work properly.
2. Check all gearboxes for moisture accumulation. Make sure each contains the proper amount and type of grease. Drain off any moisture present. If excessive moisture is evident, drain and replace the grease. Water mixed with the grease will decrease its lubrication ability and not provide the needed protection.
3. Lubricate all fittings.
4. Check the water drain valve at each span of a center pivot system.
5. Remove and clean the system end cap. Here is where sand scale and other debris collects during the summer. Remove the sand trap, flush the system, and replace the trap. Drain all water-carrying lines. Drain the booster pump case.
6. Inflate tires to recommended pressure.
7. If livestock will be in the field with the pump and pivot, they should be fenced to keep the livestock away.

Productive Wells need Fall Chlorination

The well is the heart of any irrigation system when the water source is groundwater. Most groundwater in North Dakota contains small amounts of iron, which provide energy for the growth and development of iron bacteria. These bacteria form a slimy, gelatinous mass on the well screen, casing, pump and in the aquifer surrounding the well screen. If your irrigation equipment has a rust color due to the water or the water has a rotten egg smell, then growth of iron bacteria in the well is a good possibility.

The spread of iron bacteria in the well reduces the amount of open area of the screen and the open area of the spaces in the aquifer formation, thus reducing the well yield. Reduced well yield will affect the operation of the irrigation system and could reduce yields, especially with high value crops like potatoes. The only way to effectively control iron bacteria is by chlorinating the well on an annual basis.

Well chlorination should be performed in the spring and the fall. The object of well chlorination is to raise the chlorine level in the well to 500 parts per million (ppm) and hold it there for a period of time to allow the chlorine to attack and kill the bacteria. It is especially important to also get the chlorine out into the aquifer material surrounding the well screen, Figure 2.

Figure 2. Annual chlorination of a well is needed to control iron bacteria.

The two common sources of chlorine used in well chlorination are household bleach that contains about 5% chlorine and a dry form of calcium hypochlorite sometimes called HTH. HTH contains about 70% available chlorine and can be purchased from swimming pool companies, well drillers and some irrigation dealers. I recommend using common household bleach for a couple of reasons. Chlorine is a noxious and dangerous gas. Household bleach is the safest form of chlorine to handle because of its low level of chlorine. Second, it is easy to obtain as almost all grocery and convenience stores have it in stock.

Irrigators with oil-lubricated, deep well turbine pumps should be especially careful if they use HTH to chlorinate their wells. It is common for these wells to have a layer of oil on top of the water. Mixing chlorine and oil can have explosive repercussions, so if a granulated or pellet form of chlorine is used for chlorination, mix it with a suitable amount of water before pouring into the well.

It is important to chlorinate the well before you pump out your pipelines for the winter. Use the following procedure to chlorinate your well(s):

1. Determine the depth of water standing in the well. This is the total well depth minus the depth to static water.
2. From Table 1, determine the amount of chlorine needed. For example, if you have a 12-inch diameter well 100 feet deep and the static water level is at 20 feet, the column of water is 80 feet deep. The amount of chlorine bleach needed is 8 x 0.6 gal/10 ft or 4.8 or 5 gallons. The amount of HTH needed would be 8 x .35 pounds/10 ft or 2.8 pounds.
3. Introduce the chlorine into the well using one of the following methods. Use protective gloves and goggles. Chlorine solutions this strong can cause skin burns.

1. Using HTH pellets, drop through the casing access hole to the bottom of the well (with oil lubricated turbines do this very slowly).
2. Using HTH granules or powder, dissolve slowly by adding to 10 gallons of water or more. Pour into the well then add at least 100 gallons of water to distribute throughout the well.
3. Using liquid bleach, pour into 10 gallons of water and pour into the well. Add at least 100 gallons of water to distribute throughout the well.

4. Allow to stand for at least four hours.
5. Surge the water in the well by starting and stopping the pump. Don't allow the water to discharge from the well. This action is also called "rawhiding" a well. Do this at least four times. For deep well turbine pumps with electric motors, allow five minutes between starts to allow the water to flow back into the well.
6. Force the chlorine into the aquifer by pouring in at least 100 gallons of water.
7. Let the chlorine stand in the well for 24 hours. Chlorine needs time to kill iron bacteria.
8. Surge the well at least twice more then pump the water to waste. This water can be pumped through the irrigation system. In fact it will help clean out pipelines and spray nozzles. Stand upwind because the chlorine smell could be strong. Pump until the odor of chlorine is gone.