Investigations of serviceability failures of building floor slabs supported by stone columns in very soft clays prompted a review of the methods for predicting the settlement reduction achieved by the columns. Data from both successful case histories and serviceability failures indicate that, in practice, settlement reduction for widespread loading of very soft clays may be both quite limited and overestimated by current design methods. Analysis of long-term settlement observations from two serviceability failures suggests that the reduction in secondary settlement achieved by the stone columns was also quite limited. Based on these findings it is considered that the range of loadings and thicknesses of very soft clay for which stone columns would be viable for widespread building loads is likewise limited. A review of the serviceability failures led to the conclusion that inadequacies in the procurement of the design and construction of the stone columns contributed to the failures.

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At Peasmarsh in East Sussex a 70 ~ cutting, between 6.5 and 11 m high, was made in the Hastings Beds using the soil nailing technique in conjunction with a seeded geomat to provide a 'green' finish. Engineering geological investigations led to the adoption of soil nailing, and the design and installation of the nails. The cut slope and selected nails were instrumented and the cutting's performance observed.

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Spawning, larval rearing, and growout of Ruditapes largillierti (Philippi 1849) were investigated in a series of trials conducted at the University of Tasmania (UTAS), Launceston and Georges Bay, St Helens, Tasmania, Australia. Intramuscular injection of serotonin (3 × 10 -7 to 1.5 × 10 -6 moles) failed to induce spawning in female Ruditapes largillierti, although some males did spawn. Fecundity of R. largillierti induced to spawn by thermal stimulus ranged from 0.5 to 0.9 × 10 6 eggs female -1 . Fertilised eggs developed into trochophore larvae by 24 h at 20°C and D veligers with a mean shell length † Author to whom correspondence is to be addressed. M98023 Received 12 May 1998; accepted 17 August 1998of 85.3 ± 4.7 μm within 48 h. Early larvae were frequently deformed and their mortality rates were very high. Development to pediveliger stage (mean shell length 200.3 ± 7.3 μm) took between 11 and 16 days at 20°C, and metamorphosis to spat (mean shell length 240 (μm) occurred between Days 16 and 19. There was no significant difference in efficacy of epinephrine, norepinephrine, or untreated groups for inducing larval settlement. Average growth of juveniles held subtidally within trays or baskets (mesh size 1.7-12.0 mm) was 1.3 mm month -1 . The aquaculture potential of this subtidal venerid clam warrants further investigation.