equipment may very well make its salvage value less than the cost of shipping it back to the United States so that the best alternative is to place these items in stock, Whether or not any subsequent use can be made of them is problematical, It should be noted at this point, however, that several rigid checks of the proving ground inventory are made prior to all subsequent procurements in order to guarantee that no wasteful or unnecessary purchases are made. At times the inventory appears to reflect over-stockpiling of coral aggregate. Again, experience has shown that advance work of this kind is both logical and economical in view of existing conditions. The aggregate is ob- tained from coral reefs, and rate of production is necessarily slow due to normal difficulties encountered in subaqueous excavation plus frequent shutdowns due to high tides and strong wave action. Therefore, if stockpiling is held in abeyance pending actual need of the aggregate, the discontinuity of the excavation results in corresponding shutdowns of the aggregate processing plant, and these delays may even extend to the concrete and-or stabili- zation work for which the aggregate is being produced. It should be noted also that advance stockpiling is scheduled so as to contribute to a desirable level of work for the skeletal force which the Contractor must retain at the proving ground during interim periods. There is a substantial amount of expendable equipment installed in scientific facilities which receives little or no damage from the weapons tests. This equipment may have been funded by the AEC or by some other agency; but, in any event, it is recovered during the roll-up period and placed in stock because it may prove useful at some later date. tend to distort the inventory balance. Thus, actions of thrift Probably the single largest factor contributing to unfavorable inventory balances is the wide range in makes and models of equipment employed at the proving ground; Acquisitions under equipment upgrading programs to- gether with a requirement that purchases of new equipment be based on competitive bidding make impossible even a fair degree of standardization. Here again, the isolation of the PPG from sources of supply makes absolutely essential the stocking of a wide range of spare parts to insure that equipment is not kept immobile for indefinitely long periods. It should be noted, too, that non-standardization of equipment adds somewhat to the Contractor's manpower requirements in this age of specialists, and it also has a marked effect on warehousing requirements, The foregoing remarks should not be construed to mean that it is useless to maintain a vigilant guard against excessive inventories but rather to give some idea of the problems associated with inventory levels at the PPG. The SFOO is making a continuing and concerted effort to achieve a generally acceptable inventory level at the proving ground, It is believed that adoption of a more realistic accounting procedure, as outlined in the foregoing reference, would greatly assist in reaching a satisfactory solution. 74