P A Yeomans-Building a Keyline Dam (25 min) 1960

conserving water for irrigation is a problem that's been tackled in many ways but probably the most successful method is controlled damming water for irrigation can be stored in dams like these the nearest stem is a key line then located at the highest suitable site in the very the dam in the background is at the lower boundary level of the property this particular irrigated hillside was sown under grout conditions and watered three times from a key line then before rain fell this posture was also irrigated by the dam and these cattle have grazed here for ten days you Oh now let's build a dam a key line there it must be located as high as possible but still have enough induced catchments above to provide a runoff to fill it the dam will be built with earth from the valley first we take some measurements and then plan the dam on paper the first pig marks the saddle point a leveling instrument is essential for dam construction the one we use is the Bunyip level designed especially for farm work and is very simple to use to check the level press the atmosphere buttons and see that the water movement corresponds with movements in level of the stops from the saddle point we level down to the pipe outfit level and if that's the saddle point incidentally that the dam will overflow into another dam in the opposite valley this is a pig 20 feet below the high water level and represents the toe of the dam on the downstream side from this pig to the sever point is 512 feet which will be the length of the dam the valley floor slope therefore is 20 over 512 which is 1 in 25 now this is a block diagram without prepares dem and has been drawn according to the information that was obtained on the site the blue shaded area is the high water contour mark and the arrow marks the saddle point where we drove our first pig the grand plow with one shank turned down and the rest reverse to give weight now marks out the features that the pig you'll notice that the pigs are always replaced after the flower has passed this is a practice that must be strictly observed throughout the construction of the dam starting at the saddle point the plow marks in the high water contour right around the dam from the center point in the valley we determine the center line of the wall and from this line we peg the back and front toes at the wall when the plow has finished marking the bulldozers take the topsoil off the areas which will be affected by our construction work this is put to one side in Windows and will be replaced when the dam is completed the area near the wall on the upstream side is called the excavation area when the topsoil is stripped we make a cutoff trench along the centerline across the valley floor this forms a base for our wall and is designed to key the wall into the valley floor the floor of the cutoff trench is roughened up to assist bonding here we see a cross-section of our world it will be 270 feet long and 20 feet high - the water level at the center + 3 feet free board and 2 feet shrinkage allowance the cross width at the base is 100 feet tapering off to 12 feet at the crest the better slope therefore is 1 in 1 and 3/4 the shaded area at the bottom of the wall is the cutoff trench now when the cutoff trench is finished we dig a trench for the lock pipe the floor of this trench is also roughen to assist bonding Oh the lock pipe is laid usually a little to one side of the center of the valley floor the pipe must be laid dead straight and level against the trench at the upstream end maybe several feet below the original level of the valley floor these bulldozers are collecting earth from the excavation area for use in building the wall this is on the upstream side of the wall Oh the baffle plates which support the lock type must be properly sited and laid this is though that the pipe will be dead straight and level these pipes weigh about 700 pounds and are in 30-foot sections and are eight inches in diameter they can be handled quite easily and to quite sturdy and take a lot of rough handling you as an anti seat precaution a rather gasket is fitted in the babble phase when the pipe is laid it's about two and a half to three inches above the ground hence the bugs for the pipes can be easily fitted it's most important that the bolts on the baffle plates are thoroughly tightened or the gaskets will not do their work Oh a little earth is now brought into the trench by the full desert this is just sufficient for hand packing underneath the pipe we found that two men hand ramming at an oblique angle neck the earth quite satisfactory another anti seat precaution is in the form of a powder called egg yolk it's a very light powder made from expanded volcanic rock the theory is that if water does seep around the pipe the powder will move with the water and seal any leak automatically we check the firmness of the packing by digging a small hole near the pipe if we are satisfied then this completes the handwork when the bulldozer will finish the rest of the job the trench is gradually filled in by the bulldozer until it straddles the pipe that does not actually touch the baffle plates with the undercarriage this operation doesn't actually contact the earth but it does give it a uniformity of texture unless precautions are taken the end of the lock pipe may be lost we mark each end of the pipe with a large oil drum and the person the lock pipe system has been used by us on our own demonstration and experimental farms for 13 years we've devised this peasant technique so that any father and an assistant can make a dam two professional standards now the wall of the dam is beginning to take shape the fact that the inside end of the loc pipe trench is several feet below the valley floor means that we may excavate down to this level and use this earth to build our wall this represents five or six feet of Earth which rapidly increases to ten as we go up the valley on no account dig beneath the level of the base of the wall for high-efficiency bulldozer operation work on straight lines at right angles to the wall bulldozer operation efficiency can also be increased by grabbing a load quickly and going forward in second gear on the empty return run the back Ripper loosens the soil for the next load we struck rock in a few places and in others the soil was very dry rock should not comprise more than 25% of any load the better must be trimmed constantly this precaution is necessary so that if it rained during the construction the smooth wall will not absorb moisture the waves created by the builders are readily absorb water therefore it is important to level and smooth over the walls last thing on any day otherwise work will be delayed any water that does collect in the dam can be runoff through the lock pipe you the whole of the operation must be under tight control with the farmer checking the bulldozer work closely this is the back toe of the death and it's nearly ready for final shaping you be careful when working near the pipe opening to have somebody move the drum and clean around the pipe after the bulldozer his class the walls are checked for better with sleep meter and bunyip level the batter is even on both sides but the wall is shorter in the front then at the deck and the reason for this is that the shorter length of Earth will not snug so readily as the longer side once the walls have reached the required dimensions the topsoil can now be replaced this requires a little extra skill in the driver for its far easier to take soil off than to replace it evenly Oh when this is done the services may be smooth death we found that a single cable drag by two buddhas is one on top of the dam and the other at the bottom will smooth the bore never quite satisfactory the soil on the top and sides of the wall should be treated the same as a d'argent paddock the good pasture and soil on the walls will insulate them against the weather and they'll not dry out these services are going to be grassed over and super phosphate this is the entry cone for the inside or upstream end of the pipe it's covered with heavy gauge wire mesh to keep it free of debris and has an upward tilt so that in the event of wall slippage the pipe will not block the speed of the water through the pipe is nine times greater than at the point of entry this means a free pipe at all times now we fit the outlet valve this has been specially designed so that the water cannot be turned on or off too quickly and so produce water hammer you you at the side of the valve there is a small [ __ ] from which water can be drawn even though the main [ __ ] is up our Dam is now complete only two jobs remain to be done the construction of a feeder drain and an irrigation channel under Australian conditions the conservation of water presents a problem which only ingenuity and hard work can solve there are not enough experts to do all the work therefore the farmer must do some of it himself and we hope that this film will assist farmers to supervise their own water conservation scheme

Channel: Geoffrey Booth

Views: 58,073

Rating: 4.9515152 out of 5

Keywords: P A Yeomans, Keyline, Dam, Building, Yobarnie, Nevallan

Id: i5z5T378SM4

Length: 25min 3sec (1503 seconds)

Published: Sun Apr 19 2015