Mitigating Losses from Land Subsidence in the United States (1991) / Chapter Skim
Currently Skimming:
2. A Survey of Current Mitigation Measures
2. A Survey of Current Mitigation Measures
Pages 24-44
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From page 24... ...
The following survey of these efforts demonstrates that no single approach is applicable to aB cases. Approaches that are in use include voluntary and educational measures such as public information and mapping programs to raise public consciousness, regulatory schemes that require subsidence prevention or control, land-use management and building codes to reduce damage, market-based methods to transfer the costs of subsidence to the parties causing it, and insurance programs to distnbute cost more equitably.
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From page 25... ...
Drainage of organic soils LEGEND P - Public information programs ~ - Land-use management M - Mapping programs and building codes R - Regulation, prevention $ - Market-based methods and control ~ - Insurance FIGURE 17 Summary of mitigation measures by state for each type of subsidence.
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From page 26... ...
Geological Survey, Southwest Florida Water Management District, and Florida Sinkhole Research Institute offer circulars and lectures, slide shows for use in public schools, and an ongoing educational program for engineers, geologists, and insurers who must deal with the problem on a technical basis (Beck and Sinclair, 1986~. In addition, the Florida Sinkhole Research Institute publishes a quarterly newsletter, Update.
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From page 27... ...
Organic Soils The public information role of local government is illustrated in southern Louisiana, where the Terrebonne Parish Consolidated Govemment has an intensive education campaign under way to provide information about He problems of flooding, land loss along the shoreline and interior canals, and saltwater encroachment in cultivated areas. In addition to conducting detailed technical studies, the parish develops circulars, brochures, billboard displays, and slide shows aimed at a wider audience.
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From page 28... ...
Over a period of several years, the bureau worked with the state geological surveys to map abandoned mine sites, appraise subsidence hazards, and propose remedial actions.
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From page 29... ...
Susceptibility to future catastrophic subsidence in Florida has also been addressed in recent mapping (Sinclair and Stewart, 1985~. Underground Fluid Withdrawal Mapping plays an important role in bow identification and management of subsidence problems caused by fluid withdrawal.
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From page 30... ...
,, ,,,,,- ~ _ ~ ·- ? g~;/,: 1 airs ~ r 9~ FIGURE 18 Map of land subsidence in the Houston-Galveston, Texas, area from 1906 to 1978.
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From page 31... ...
In the case of land development practices that cause subsidence, they range from banning development to regulating construction practice. Mining Subsidence damage resulting from mineral extraction can be prevented or controlled by leaving some material behind for support or totally refilling mined-out volumes.
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From page 32... ...
The excavation involved 4.6 million m3 of soil and rock. Sinkholes Catastrophic subsidence associated with the formation of sinkholes is most commonly triggered by either groundwater-level declines caused by pumping, or diversion of surface runoff.
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From page 33... ...
Even where the method does not cause collapse of the preexisting voids, analysis of the resultant surface deformation may aid their detection. Underground Fluid Withdrawal Several alternatives are available to control subsidence caused by withdrawal of underground fluids.
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From page 34... ...
For small tracts of organic soils, regulatory schemes such as zoning may be feasible. For large tracts, such as the San loaquin-Sacramento River Delta, the Florida Everglades, and the Mississippi River Delta, historical experience has taught that careful preplanning based on land capability and economic opportunities is essential for successful development.
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From page 35... ...
5 :~ DYNAMO COM CACTI ON FIGURE 19 Experiment conducted by New Mexico State Highway Department to test feasibility of precompacting collapsible soils by dropping a heavy weight on the ground. (From Lovelace and others, 1982.)
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From page 36... ...
In Zone 2, special construction measures are required for subsidence damage resistance. Subsidence-resistant design could be incorporated into building codes in areas of abandoned coal mines as wed, so as to permit fun extraction without serious structural damage in areas of active mining.
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From page 37... ...
Today, about 200 waterboards staffed with expert technical and administrative personnel manage these water resources of the Dutch polders. FIGURE 20 Dutch windmills have played an important role in organic soil subsidence in Holland because they have been used to facilitate drainage of areas underlain by organic soils.
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From page 38... ...
Underground Fluid Withdrawal Land-use planning and zoning are potentially applicable to mitigating at least two of the hazards from land subsidence caused by fluid withdrawal flooding and ground rupture.
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From page 39... ...
The act provides for public safety in areas subject to surface-fault rupture by requiring developers to prepare geologic reports, cities and counties to recognize fault hazards in approving projects, and selders of real estate or their agents to disclose fault hazards. An even more comprehensive example, related to public information, is a Santa Clara County, Califomia, ordinance that enforces preconstruction geologic investigations that require all sellers of real estate within flood, landslide, or fault-rupture zones to provide buyers with a written statement of He geologic risk.
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From page 40... ...
The following three-tiered system of regulatory and management guidelines for development in organic soils regions has been proposed to mitigate subsidence hazards (Mumphrey and others, 1976; Mumphrey and Brooks, 1978~: Comprehensive Zoning Ordinance. This is an all-encompassing local land-use control to determine whether or not development will be allowed in an area sensitive to land subsidence and related flooding.
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From page 41... ...
The oldest and largest of these governing bodies is the Central and South Florida Water Management District, which covers the southeastern part of the state, including the Everglades and adjacent coastal land. Building codes can be used to address problems of differential subsidence in organic soil areas.
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From page 42... ...
The tax may be used only to stabilize subsiding areas and not to provide relief for subsidence damage. This act also requires underground coal mine operators to prevent damage from subsidence.
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From page 43... ...
Programs have been implemented to insure against losses from coal-mine subsidence and catastrophic subsidence associated win sinkhole collapse. Although it was not intended to mitigate subsidence, me National Flood Insurance Program offers relief to those impacted by flooding aggravated by subsidence.
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From page 44... ...
The Texas Gulf Coast experienced Tree major rainfalls in 1979. As a result of the flooding from these three storms, the federal government, Hugh the National Flood Insurance Program, received over 17,000 claims totaling $170,000,000.
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