Arizona republican., 1920-02-18

is iuepracticable on account Of the diI> ficulty of getting sufficient StrenStA to carry the load of back i'll upon lJ. and also on account Of excessive cost For these reasons . drain of the closed type is not feasible where larzse capacity is needed as is the case us ually with one several miles Tn lenGtIl.r Nearly all of the I-aNeeR drain all or that on the Arizona and Grand canal areas, and the upper portions of those on the Salt and New river areas can be closed The greater portion of the. last two, however. must be open chan nels. The section Of channel which has been tentatively adopted is on8 with bottom width varying rom .. to 10 feet. with l to l side slopes ands an average depth of not less than sla feet. In some instances. where dr-itTS.. do not cut porous water-Dear1nsSs strata. relief wells may he necessary to tap these strata and carry water from them up to the drain
 Wells and Pumping Plants
 The additional wells for the south side should be of the same type and size as those already constructed The locations are in good water producing territory. and no doubt wells of rom 2 to second feet capacity can be oe-. tained On the north side where con ditions are less favorable il is queS-s tionable if wells exceeding l second' foot capacity can be obtained Here a smaller and less expensive type of well and pumping equipment can be used. II is estimated that a 1O-inch well is the maximum size that will be required in this section
 What the System Is Expected to
 Accomplish
 The works outlined. together with the wells already constructed, it is OK pected. will be sufficient 10 lower the ground water to d safe depth over the
 
 reasonable care is exercised in the ese of water The lowering Of the water table over these areas will also have the effect of protecting adjacent ones and preventing the further spread Of seepage. It cannot be positively stated that no additional drainage works cI' pumping will be required The rise in ground water depends upon many uEl- derground conditions which are diffa- cult to determine The TeclanatloE1 and protection of areas now wet pTs threatened will, however. be an 1as- portant factor in affording protectiosl to all of the lands of the project. A Additional Pumping for Water Supply
 The works outlined above represent the minimum that can be considered adequate for drainage purposes AS this report is intended 10 deal with given to that question rather than 10 the development of an additional Wa ter supply through pumping IL is ex- pected, as heretofore stated, that the works outlined will serve to lower tho ground water over the seeped= alld threatened areas and protect them from. danger. To accomplish this it may he necessary to operate the pumps for all or a greater portion of the time In other words, it iS estimated IhaC the capacity of wells and drains ls about equal to the quantity that must be removed to keen ground water aC a safe depth. 4 greater conservation of water can be brought about by in creaSing the number of wells so that their capacity will exceed drainage re- quirements. This will permit of 8 larger amount of pumping. and 1he lowering of ground water to a greater depth than is required for drainags during seasons when the reservoir ls low and the supply Of gravity water inadequate By thus lowering the ground water supply during dry sea sons the amount of pumping required. during periods when there is an am pie supply in the reservoir will be re- duced. Such a plan will make posSi- ble a greater conservation of the en- tire water supply of the valley and offer protection against water shortage during dry periods In view Of the above, consideration may properly be given to further increasing the pumping capacity of the project lC is my Judgment. however, that the construction of additional wells ex- cept those required for drainage pJr-- poses. should be delayed until LhoSa now installed have been operated r0 nearly their full capacity for at least one season. During this period carv- full measurements should be made on the elevation of ground water over the entire project The data thus obtained will be of the greatest value. and Will be necessary to properly determine lIe number and location of additional