Relief Wells: Difference between revisions
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|caption= "Figure 7-9. Relief well seepage outflow. Although relief wells are not typically installed for the primary purpose of seepage water monitoring, their outflow can be collected, measured, and evaluated similar to open piezometers or observation wells."<ref name="FEMAP1032" /> | |caption= "Figure 7-9. Relief well seepage outflow. Although relief wells are not typically installed for the primary purpose of seepage water monitoring, their outflow can be collected, measured, and evaluated similar to open piezometers or observation wells."<ref name="FEMAP1032" /> | ||
(Image Source: [https://commons.wikimedia.org/wiki/Category:Diamond_Valley_Lake#/media/File:DVL-Westdam.JPG FEMA]) | |||
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"All water retention structures are subject to seepage through their foundations and abutments. In many cases the seepage may result in excess hydrostatic pressures or uplift pressures beneath elements of the structure or landward strata. Relief wells are often installed to relieve these pressures which might otherwise endanger the safety of the structure. Relief wells, in essence, are nothing more than controlled artificial springs that reduce pressures to safe values and prevent the removal of soil via piping or internal erosion. The proper design, installation, and maintenance of relief wells are essential elements in assuring their effectiveness and the integrity of the protected structure."<ref name="EM 1110-2-1914">[[Design, Construction, and Maintenance of Relief Wells (EM 1110-2-1914) | Design, Construction, and Maintenance of Relief Wells (EM 1110-2-1914), USACE, 1992]]</ref> | |||
“Relief wells are typically vertical drains placed to relieve uplift pressure at the downstream toe of an embankment. [[Piezometers]] are typically located equidistant between two wells. Under maximum hydraulic load, the piezometric level at the downstream toe of an embankment should be lower than the ground surface”.<ref name="EM 1110-2-1908">[[Instrumentation of Embankment Dams and Levees (EM 1110-2-1908) | Instrumentation of Embankment Dams and Levees (EM 1110-2-1908), USACE, 2020]]</ref> | |||
"Relief wells also function as observation wells, but their primary purpose is to reduce the hydraulic head at selected locations along the seepage flow path... Relief wells for dams have specific problems associated with the plugging of the filter packs or the accumulation of bacteria or carbonates (USACE 1995). It is often necessary to install piezometers adjacent to relief wells to measure and monitor the pressure increases associated with clogged wells. Relief wells typically require regular maintenance for long-term proper functioning, including re-development, chemical treatments, and disinfection."<ref name="FEMAP1032">[[Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032) | Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032) | "Relief wells also function as observation wells, but their primary purpose is to reduce the hydraulic head at selected locations along the seepage flow path... Relief wells for dams have specific problems associated with the plugging of the filter packs or the accumulation of bacteria or carbonates (USACE, 1995). It is often necessary to install piezometers adjacent to relief wells to measure and monitor the pressure increases associated with clogged wells. Relief wells typically require regular maintenance for long-term proper functioning, including re-development, chemical treatments, and disinfection."<ref name="FEMAP1032">[[Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032) | Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032), FEMA, 2015]]</ref> | ||
== | ==Best Practices Resources== | ||
{{Document Icon}} [[Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032) | Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032) | {{Document Icon}} [[Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032) | Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032), FEMA]] | ||
{{Document Icon}} [[Instrumentation of Embankment Dams and Levees (EM 1110-2-1908) | Instrumentation of Embankment Dams and Levees (EM 1110-2-1908) | {{Document Icon}} [[Instrumentation of Embankment Dams and Levees (EM 1110-2-1908) | Instrumentation of Embankment Dams and Levees (EM 1110-2-1908), USACE]] | ||
== | ==Trainings== | ||
{{Video Icon}} [[On-Demand Webinar: Evaluation and Maintenance of Piezometers, Relief Wells, and Drains in Dams and Levees]] | {{Video Icon}} [[On-Demand Webinar: Evaluation and Maintenance of Piezometers, Relief Wells, and Drains in Dams and Levees]] | ||
Latest revision as of 15:51, 18 July 2023
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| "Figure 7-9. Relief well seepage outflow. Although relief wells are not typically installed for the primary purpose of seepage water monitoring, their outflow can be collected, measured, and evaluated similar to open piezometers or observation wells."[1]
(Image Source: FEMA) |
"All water retention structures are subject to seepage through their foundations and abutments. In many cases the seepage may result in excess hydrostatic pressures or uplift pressures beneath elements of the structure or landward strata. Relief wells are often installed to relieve these pressures which might otherwise endanger the safety of the structure. Relief wells, in essence, are nothing more than controlled artificial springs that reduce pressures to safe values and prevent the removal of soil via piping or internal erosion. The proper design, installation, and maintenance of relief wells are essential elements in assuring their effectiveness and the integrity of the protected structure."[2]
“Relief wells are typically vertical drains placed to relieve uplift pressure at the downstream toe of an embankment. Piezometers are typically located equidistant between two wells. Under maximum hydraulic load, the piezometric level at the downstream toe of an embankment should be lower than the ground surface”.[3]
"Relief wells also function as observation wells, but their primary purpose is to reduce the hydraulic head at selected locations along the seepage flow path... Relief wells for dams have specific problems associated with the plugging of the filter packs or the accumulation of bacteria or carbonates (USACE, 1995). It is often necessary to install piezometers adjacent to relief wells to measure and monitor the pressure increases associated with clogged wells. Relief wells typically require regular maintenance for long-term proper functioning, including re-development, chemical treatments, and disinfection."[1]
Best Practices Resources
Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032), FEMA
Instrumentation of Embankment Dams and Levees (EM 1110-2-1908), USACE
Trainings
Citations:
Revision ID: 7270
Revision Date: 07/18/2023