Bible Records of George Black and Margaret Clifton, His Wife
Title | Bible Records of George Black and Margaret Clifton, His Wife PDF eBook |
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Genre | Pinyard Bible records |
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Origin, Diagnostics, and Mitigation of a Salt Dissolution Sinkhole at the US Strategic Petroleum Reserve Storage Site, Weeks Island, Louisiana
Title | Origin, Diagnostics, and Mitigation of a Salt Dissolution Sinkhole at the US Strategic Petroleum Reserve Storage Site, Weeks Island, Louisiana PDF eBook |
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Release | 1995 |
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Sinkhole Progression at the Weeks Island, Louisiana, Strategic Petroleum Reserve (SPR) Site
Title | Sinkhole Progression at the Weeks Island, Louisiana, Strategic Petroleum Reserve (SPR) Site PDF eBook |
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Pages | 17 |
Release | 1995 |
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A sinkhole measuring 11 m (36 ft) across and 9 m (30 ft) deep was first observed in alluvium overlying the Weeks Island, Louisiana, salt dome in May 1992, but it was about a year old, based on initial surface appearance and subsequent reverse extrapolation of growth rates. A second and much smaller sinkhole was identified in early 1995, nearly three years later. Their position directly over the edges of the SPR oil storage chamber, a former room-and-pillar salt mine, caused apprehension. The association of sinkholes over mines is well established and this occurrence suggested that groundwater influx undoubtedly was causing salt dissolution at shallow depth, and associated collapse of soil at the surface. Leaks of groundwater into other salt mines in Louisiana and elsewhere led to flooding and eventual abandonment (Coates et al., 1981). Consequently, much attention has been and continues to be given to characterizing these sinkholes, and to mitigation. This paper summarizes current engineering geologic concepts, and briefly describes diagnostic and risk mitigation efforts being conducted by the US Department of Energy, operator of the Strategic Petroleum Reserve (Bauer et al., 1994).
Salt Dissolution Sinkhole at the Weeks Island, Lousiana, Strategic Petroleum Reserve Storage Site
Title | Salt Dissolution Sinkhole at the Weeks Island, Lousiana, Strategic Petroleum Reserve Storage Site PDF eBook |
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Release | 1994 |
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Geotechnical Studies Associated with Decommissioning the Strategic Petroleum Reserve Facility at Weeks Island, Louisiana
Title | Geotechnical Studies Associated with Decommissioning the Strategic Petroleum Reserve Facility at Weeks Island, Louisiana PDF eBook |
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Pages | 11 |
Release | 1997 |
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The first sinkhole at the Weeks Island Strategic Petroleum Reserve (SPR) site was initially observed in May 1992. Concurrent with the increasing dissolution of salt over the mined oil storage area below, it has gradually enlarged and deepened. Beginning in 1994 and continuing to the present, the injection of saturated brine directly into the sinkhole throat some 76 m beneath the ground surface essentially arrested further dissolution, providing time to make adequate preparation for the safe and orderly transfer of crude oil to other storage facilities. This mitigation measure marked the first time that such a control procedure has been used in salt mining; previously all control has been achieved by either in-mine or from-surface grouting. A second and much smaller sinkhole was noticed in early 1995 on an opposite edge of the SPR mine, but with a very similar geological and mine mechanics setting. Both sinkholes occur where the edges of upper 152 m and lower 213 m mined storage levels are nearly vertically aligned. Such coincidence maximizes the tensional stress development, leading to fracturing in the salt. This cracking takes 20 or more years to develop. The cracks then become flow paths for brine incursion, which after time progress into the mined openings. Undersaturated ground water gradually enlarges the cracks in salt through dissolution, leading to eventual collapse of the overlying sand to form sinkholes. Other geologic conditions may also be secondary factors in controlling both mining extent and sinkhole location.
Mine-induced Sinkholes Over the U.S. Strategic Petroleum Reserve (SPR) Storage Facility at Weeks Island, Louisiana
Title | Mine-induced Sinkholes Over the U.S. Strategic Petroleum Reserve (SPR) Storage Facility at Weeks Island, Louisiana PDF eBook |
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Pages | 5 |
Release | 1997 |
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A sinkhole formed over the former salt mine used for crude oil storage by the U.S. Strategic Petroleum Reserve at Weeks Island, Louisiana. This created a dilemma because in-mine grouting was not possible, and external grouting, although possible, was impractical. However, environmental protection during oil withdrawal and facility decommissioning was considered critical and alternative solutions were essential. Mitigation of, the sinkhole growth over the salt mine was accomplished by injecting saturated brine directly into the sinkhole throat, and by constructing a cylindrical freeze curtain around and into the dissolution orifice at the top of the salt dome. These measures vastly reduced the threat of major surface collapse around the sinkhole during oil transfer and subsequent brine backfill. The greater bulk of the crude oil was removed from the mine during 1995-6. Final skimming operations will remove residual oil trapped in low spots, concurrent with initiating backfill of the mine with saturated brine. Environmental monitoring during 1995-9 will assure that environmental surety is achieved.
Summary of Events and Geotechnical Factors Leading to Decommissioning of the Strategic Petroleum Reserve (SPR) Facility at Weeks Island, Louisiana
Title | Summary of Events and Geotechnical Factors Leading to Decommissioning of the Strategic Petroleum Reserve (SPR) Facility at Weeks Island, Louisiana PDF eBook |
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Pages | 44 |
Release | 1996 |
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A sinkhole discovered over the edge of the Strategic Petroleum Reserve storage facility at Weeks Island salt dome, Louisiana, led to decommissioning the site during 1995--1998, following extensive diagnostics in 1994. The sinkhole resulted from mine-induced fractures in the salt which took may years to develop, eventually causing fresh water to leak into the storage chamber and dissolve the overlying salt, thus causing overburden collapse into the void. Prior to initiating the oil removal, a freeze wall was constructed at depth around the sinkhole in 1995 to prevent water inflow; a freeze plug will remain in place until the mine is backfilled with brine in 1997--8, and stability is reached. Residual oil will be removed; environmental monitoring has been initiated and will continue until the facility is completely plugged and abandoned, and environmental surety is achieved.