Arizona republican., 1920-02-18

| pressure under which it is confined.
 Generally the water bearing strata
 are too deep to be tapped by drains.
 It is my conclusion that drainage of
 this area can best be accomplished by
 means of pumping. Conditions are un- | favorable for obtaining wells of large 1 capacity. and it will be necessary probably to use a number of small i wells. How many will be required cannot be answered with any certain i ty until some have been sunk and | their capacities determined It is l estimated roughly that from 12 to 15 second feet. in addition to the six l second feet developed by the four wells now in operation will be suf- i ficient to care for the entire area. On
 a basis of an average yield of &
 second foot per well, from 16 to 70 wells will be required. On that portion l of the area east of the Old Cross Cut canal. water travels down the slopes
 relatively near to the surface. Here it seems feasible to intercept it by means of a. deep drain which can be discharged into the Old Cross Cut canal.
 Plan Of Drainage
 On the map, drawing No. ,, are shown the general location of drains. waste ditches for pumped water, and pumps for a system intended to re- lieve the areas above described. The locations for the drains are the pre- liminary ones that have been laid out on the ground for the purpose of de termining grades, feasibility of con struction. and also to serve basis for estimates. They are subject to changes in making final plans
 The locations for wells, especially in the Arizona and Grand canal area are tentative Neither are they intended to represent the number of wells that will be required. This, as has been stated. depends upon the capacity of the wells that can be obtained The locations are intended to show roughly the lines along which wells should be developed. The locations on the south side are believed to be satisfactory for the relief of that portion of the project south and east of the Tempe district
 over which ground water is high enough to cause damage
 Waste Oitches for Pumped Water
 it IS intended that the pumped wa ter, insofar as it is possible. will he used to supplement the reservoir SUD- ply for irrigation. It may not be nos slbie always to use all of the pumped water for the following reasons. The capacity of pumps may exceed the re- quirements for lands below them dur ing some portions of th< year. and the pumps may have to be operated during the n-1rrlgating season to hold the ground water at a safe depth The quality of water from some of the
 2
 tion on account of a high content of harmful alkali in solution
 Attention was called in the hoard report or last year, to the plan of mix Ing the pumped water with several times its volume of river water so q : 10 procure supply of unquestionable quahty- By frequent analysis of the waters from each of the wells and careful supervision of their blending with river water the alkali content can be kept below what may be regarded as a safe limit. It is of the highest importance when pumped waters con tain a high percentage of alkali that lands be protected from damage due to their use. It seems certain also that some of the pumps especially those along the Salt canal and on the New River areas be operated for drainage purposes at times when it will not be feasible to use the pumped supply for irrigation. The same will undoubted- ly be true also of the new wells pro posed for the south side area.
 The above conditions make it de- sirable that waste-water ditches be provided to carry the supply which cannot be used, off the project. The exact number and location of these ditches, that will be required ulti- mately. is difficult to determine with the information now available. It is my judgment that, in order to make efficient use of the pumps for drain age purposes. the waste water ditches shown on the map should be con- structed.
 Character of Drains
 Drains. to be effective should have an average depth of about ten feet. | In order to reduce the areas required | for .ights of way and property da- | images to a minimum. drains should | be of the closed type where ever DOS sible- The capacity of a closed drain ] is. however limited to that of the | pipe used The use of very large pipe | <