2-in.-diam PVC pipe was rorced into layer at each location is at least the hole. equivalent a The pipe was capped at the bottom to prevent the water depths The slots Before the water in the wells was above the waterline were taped over sampled, to prevent surltace debris from enter- for one to two days. “ing the casing from above. in Table 1. soil from filling the interior or the pipe. to The hole it wag allowed to stabilize The entire pumping system was purged with at was backfilled with the excavated least 100 litres of water from any soil, respective well, and all collection with the removed bottom soil being returned to the pit first. Table 1 gives the depth containers were thoroughly rinsed to ninimize cross-contaminaltion of to which the slotted casing extends below the samples. surface of the water table and the a battery-operated pump (Fig. depth of the water table below ground through a section of flexible plastic surface. tubing lowered into the pipe below were measured during periods of low- the water surface. The pumping rate est tide. could be regulated by a variable- Most of these water depths We detected no differences in conductivity throughout Samples were withdrawn by 2) speed control over the range from a the acces-— sible length of each water column. few millilitres per minute to & The litres per minute. thickness of the freshest water Table 1. Tsland Bikini HEH HEU HEH HFH HFH 1.21 O.73 0.87 0.82 QO. 73 2.48 2.72 2.33 2.80 2.07 FWR 1 0.54 2.43 FWR 3¢ 9.0 4.0 --© -¢ FWR 2 FWR 4@ a Old well. Depth of water table below ground surface (mn) L 2 3 4 5 FH 72 Enec Depths of wells at Bikini and Eneu Islands. Depth of well. casing below water table (im) Well Conductivity was b 0.6> QO. 81 . Open well under block casing. dy 1.92 c Not measured.