20 from the dome were shipped to the Portland Cement Association for testing. These tests showed that the ccapressive strengths of 1 the cores were high and that the cores exhibited no properties that] would lead to premature deterioration. Pour key~wall sections were cored, with the hole penetratin appioximately 8 feet below the bottom of the key-wall. Three showed good quality concrete, but the lower half of one was friable, rc quality concrete. The latter key-wall section rested on highly fractured, moderately to well cemented beachrock. The other thiee rested on uncemented medium to fine sand. In one, the concretejwas separated from the sand by a l-foot layer of dark brown bentonife or attapulgite with low shear strength. The overall conclusion is that the key-wall sections are of] good quality concrete with some segregation of cement and aggregate 4t the bottom. They rest on a fractured coral or sand foundation. An interesting observation made during the key-wall drilling was water level in the drill holes appeared to be nearly synchronou the tide, which suggests that water flows freely between the co of the crater and the ocean. As noted, the concrete dome consists of 11 rings of panels. holes were drilled and sampled through the third ring from the It was expected that after penetrating the cap, the drill would encounter soil-cement concrete, then tremie concrete, then cra back, and, finally, the coral beneath the true crater bottom. the holes actually entered the undisturbed coral, but all penetgated into the fall-back zone. In the first hole the material immediately under the cap wa uncemented medium to fine soil-cement mixture with a few gravel chunks of hardened cement. This continued for 12.5 feet and wa followed by 3.5 feet of “oversize material” consisting of algal cobbles, broken pieces of tree limbs and boards, wire, anc r#ba a depth of 17 feet a section of 6-insh layers of poorly to mode cemented tremie concrete alternating with uncemented soil and o debris began. This material had a strong smell of ammonia and tinued for 5 feet. The next 2 feet, which smelled of hydrogen qdulfide, consisted of oversize debris and cobbles. This was followed byjf1l foot of well cemented tremie. The succeeding 6.5 feet had alternati layers of poorly to moderately cemented tremie concrete and ove cobbles, soil, rebar, and wood fraycsents. Under this was 6 inc well cemented tremie covering an unrecovered 5-foot section in cuttings showed soil, minor gravel-size tremle, and wood fragme The remaining 15 feet of the core consisted of crater fall—-back medium to fine grain coraline sand and minor fractured gravel. In order to determine the relative permeability of the crat contents, percolation tests and pumping recovery tests were con in the boreholes. Details from these permeability tests are re by Ristvet (1980) and onsy the results are summarized here. Th colation tests, which involved filling the boreholes with water level >of the cap base and then observing the water drop with t conducted in the soil-cement layer. Although the results were variable from borehole to borehole and at different depths with borehole, the rate of water level drop in the soil-cement gener very low; in one test there was no water level drop after 12 ho