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, enlarged by forcing the tapered shank into it. This formed a short nipple protruding into the pipe, which was then threaded with the stand- ard 3/8-in pipe tap built into the tool. The nipple was sufficiently long for four to five full threads. The connection was completed by in- stalling a gasket (made with room-temperature vulcanizing silicone rubber in a plaster of paris mold) and washer, and screwing a threaded tee-connector with barbed side arms into the threaded hole (as sho"TI). Coating the rubber gasket with silicone caulking compound before it is installed helped form a water-tight seal. After 8 months of operation, only one leak (caused by a cracked silicone rubber washer) has developed in the Tacna, Arizona, system. A simpler technique, which eliminates the threaded fitting and molded gasket, was used to install the system in Riverside. The hole was cut and enlarged the same way as is shol'" in Fig. 2, except it was not threaded and was located on a ridge instead of in a valley of the corrugations. (Locating the hole on a ridge seems to distribute the stress, caused by stretching, more uniformly around the nipple wall.) With the nipple formed, the tool was withdrawn and the small diameter polyethylene delivery hose was immediately inserted. The stretched plp-stic shrinks around the hose forming a water-tight seal. After several days, the force required to dislodge delivery tubes from lateral pipes exceeded 5 kg (11 Ib). Confined by the backfill in the trench a~d subjected to water pressure of no more than 30 kPa (5 psi), it is unlikely that the hose will pullout of the pipe. After more than 4 months of operation, no leaks have developed in the system at Riverside, California. At the Tacna site, the small diameter delivery hoses were laid in trenches dug from each tree to the lateral trench. Making these trenches was time-consuming and considerable hand labor was required to clean them at their intersection with the lateral trench. This problem was eliminated at the Riverside site by using a water jet to force a small diameter pipe from the trunk of a tree to the lateral trench. By slip- ping the delivery hose onto the barbed fitting at the end of this pipe (Fig, 3), when the pipe was withdrawn the hose was drawn into the hole. It was then a simple procedure to connect each delivery hose into the corrugated lateral by the procedure described above. Figure 4 shows hoses installed in a corrugated pipe, lying in a trench ready to be backfilled. A simple procedure to determine the proper elevation of the supply hose at each tree to provide equal flow rate is as follows. First, by standing water at a fixed static head in the lateral, a reference level can be found and marked on each tree by lowering each supply hose until the water level stands at its opening. During the procedure, all other hoses should be kept elevated above this level so that water does not flow from them, causing a pressure head gradient within the lateral. All subsequent elevation measurements are made relative to this refer- ence elevation. The second step is to estimate the head loss that will occur within the lateral between each pair of hose connections when t~~~~4fs -4-