Empirical Correlations for Compressibility Indices of the Varved Soil Deposits in the New Jersey Meadowlands

The New Jersey Meadowlands is roughly 80 square kilometers of wetlands, uplands, and developed areas located in the Hudson and Bergen Counties of New Jersey. The results of various laboratory tests including consolidation and shear strength tests on undisturbed soil samples collected from a total of 40 standard penetration test boreholes drilled at 17 sites throughout the Meadowlands are presented in this paper. Based on the boring logs, the subsurface profile in the Meadowlands composed of a tidal marsh deposit of thickness less than 10 m, which consists of very soft to soft peat and organic clayey silt. The major deposit in the Meadowlands is composed of very soft to medium varves of silty clay and clayey silt, whose total thickness exceeds 25 m in some areas. The consolidation tests were performed on 11 samples from the tidal marsh and 65 samples from the varved soil deposits. The laboratory data indicate that the peat soil which has an organic content greater than 50% exhibits significantly higher compressibility than the organic clayey silt with a much lower organic content. Average values of the Atterberg limits and the compression and swell indices for the varved soils are close to the typical values for the Boston blue clay. Profile of overconsolidation ratio indicates that the peat and organic soils and the varved soils below a depth of 10 m are normally consolidated to moderately overconsolidated, while the varved soils in the top 10 m are moderately to heavily overconsolidated. Published empirical correlations generally underestimate the compression and swell indices (C_c and C_s, respectively) of the varved soils; therefore, four new correlations to better estimate the values of C_c and two new correlations to better estimate the values of C_s for the varved soils in the Meadowlands are derived in this study.