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of Kennewick,Washington for some initial assistance when it was starting up the SCBID <br /> drainage maintenance program many years ago. <br /> 4. To clean out an old tile drain system,and to properly integrate it with the existing surface <br /> drainage system, SCBID drainage maintenance staff recommended that the 25 Arkansas Valley <br /> drainage districts start at the lowest sites/structures in their drainage systems,and work up to the <br /> top. One approaches a thorough rehabilitation of the drainage system by building a map of the <br /> underground drainage system,and creating an inventory database for it,as one works up and <br /> cleans out the system. One works upstream with the jet stream and saw equipment,clearing the <br /> drains and repairing/installing manholes as they are needed. Meanwhile,every drain and <br /> manhole is given a location name which is entered on a spreadsheet as the system is cleaned. If <br /> you reach a blockage in the drainage system,you dig up the drain and install a manhole with a silt <br /> trap. You then continue cleaning and go to the next blockage,numbering/naming the drain <br /> and/or new manhole as you proceed. <br /> 5. The rehabilitation should involve the installation of observation wells on a square mile grid for a <br /> drainage management program,and as additionally needed. Water contour maps can be <br /> developed with these wells. These observation wells will also help the drainage maintenance <br /> program identify emerging problems with the drainage system. <br /> 6. If new subsurface drains are being installed or added to the system,the trunk lines are laid out <br /> first,followed by lateral and sublateral drains. It is desirable,as a matter of design,to make sure <br /> that there is a desirable place for all of the water to go. <br /> 7. Upon completion of the rehabilitation,when annual system maintenance is being performed with <br /> jet cleaning and sawing,the program can use a monitor probe(camera)as needed to help <br /> determine maintenance requirements in subsequent years. Again,this is where the sewer industry <br /> comes in so handy. The drainage maintenance program is simply adapting the evolving <br /> technology of the sewer industry to subsurface drain maintenance;the only difference being that <br /> water is generally flowing all of the time in an irrigation drainage system. <br /> Some final observations from the visit to the South Columbia Basin Irrigation District's subsurface <br /> drainage maintenance program included the following: <br /> 1. Is a 90 year old drainage system too old to salvage? No! But Lower Arkansas Valley growers <br /> will need to nurse it back into shape. Towns often have old sewer systems that are rehabilitated. <br /> Initial equipment purchases and training of a small staff will cost a little. But once these <br /> investments have been made,the Lower Arkansas Valley program should be off and running. <br /> 2. A Lower Arkansas Valley project designed to address drainage rehabilitation will struggle with <br /> existing drainage district boards and growers,particularly with the concept of drainage district <br /> consolidation. In addition,the subsurface drainage system is"out of sight and out of mind." <br /> However, it is equally as important as the surface water delivery system for irrigating crops. <br /> PLAN OF STUDY <br /> The study will be conducted in two phases,and completed in two years. An interim report will be <br /> provided at the end of Year 1. A final report will be provided at the end of Year 2 with data on the results <br /> of Phase I cleaning and monitoring activities. Although the project is for two years, a third year of data <br /> 12 <br />