SOILS, FERTILIZERS AND IRRIGATION 65 



We would not recommend this method. The cost of tunneling be- 

 low the water line is very expensive and unless the ground on each side 

 of the water stratum is of solid clay it would be necessary to curb the 

 tunnels, which, if done with redwood, would last but a short time and if 

 of concrete would be very expensive. Obtaining water by tunnels is com- 

 mended where there is one stratum only a short distance below the ground 

 and a foot or two in thickness only or where the character of the water- 

 bearing strata is so close, such as shale or sand only, that sufficient water 

 will not flow through to an ordinary well. The tunnel method increases 

 the percolating area and increases the supply. Our recommendation 

 would be to sink a pit to the first water, drill one or more 10-inch wells, 

 20 to 30 feet from the present well, run narrow tunnels, which in this 

 case will be above the water line, out to these new wells and connect all 

 of the wells with proper pipes to one vertical centrifugal pump placed in 

 the pit. The cost of drilling additional 10-inch wells will be very slight 

 compared to the cost of the tunnel method. E. P. McMurtry. 



Linings for Irrigation Ditches. 



Please give information about cementing or lining a ditch, as to 

 the best and cheapest way and approximate cost. 



From experience with the efficiency of the different types of linings, 

 the following results can be anticipated : 1. A good oil lining, con- 

 structed with heavy asphalt road oil, applied on the ditch sides and bed 

 at the rate of about 3 gallons per square yard, will stop 50 to 60% of 

 the seepage. 2. A well-constructed clay puddle lining is as efficient as 

 a good oil lining. 3. A thin cement mortar lining, about one inch thick, 

 made of one part cement to four of sand, will prevent 75% of the seepage. 



4. A first-class concrete lining, three inches thick, made of one part of 

 cement to two of sand and four of gravel, will stop 95% of the seepage. 



5. A wooden lining, when new, is as efficient as a concrete lining, but 

 after two or three years repairs will become an important item, and by 

 eight or ten years will require complete renewal. 



The cost of an oil lining where oil can be bought at California prices 

 (about two cents a gallon) is about one-half cent per square foot. Ce- 

 ment mortar lining one inch thick costs about 2 to 4 cents per square foot. 

 Cement concrete two inches thick costs from about 4 to 6 cents, and 

 three inches thick from about 6 to 8 cents a square foot. These prices 

 do not include the trimming and preparation of the ditch before the 

 lining is put on, which would add from 54 to 1^2 cents per square foot. 

 If clay is close at hand it can be hauled and spread on the canal, then 

 either tramped in by cattle or worked in by dragging chains over it, at 

 a cost of less than 1 cent per square foot, but there are localities where 

 enough money has been spent on clay linings to pay for a good concrete 

 lining. Wooden lining built of two-inch lumber nailed on sills and side 

 yokes will cost as much as a two-inch concrete lining and is not nearly 

 as durable. 



An oil lining stops only a part of the seepage losses, and while it 

 will resist erosion well, it probably will not prevent the growth of weeds 



