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&M Angeles, A p ril 5, 3.933 9436-3-W Us, e . RI Gray, president, OiE^a, Kebraaha. Bear S ir : Please re fe r to your le tte r, March. 31, regarding depreciation on wood stare and east ire s pipe lin es, at Yens© and las Vegast While there is considerable data m • the- l i f e o f cast iron pipe, Indicating periods o f use f r o m SO to w ell over 100 years in certain s o ils , there is «eager in­formation re la tiv e to useful service in desert te r r ito r y . In th is connect ion, Observation indicates a la rge varia­tio n in cheasioal action upon pipe® i® adjacent d is tric ts * th erefo re, availab le data is not applicable to te rm end la s Vegas. ' • Certain- experlwents are being conducted a t iau Diego, Sanford and Buttoawillow, C a liforn ia , where i t is found th at oast iron pipes under te s t are lo sin g respect­iv e ly 1.569, 1.37? and 3.144 ounces per square fo o t per year; however, the tests have been conducted fo r only seven years, and a t the present tim e experts are act able to determine depreciation fo r these lo c a litie s where