Seepage Surveillance & Monitoring: Difference between revisions
Rmanwaring (talk | contribs) (Created page with "__NOTOC__ ---- <!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed --> Nearly every dam experiences seepage to varying degrees. Depending on the type of dam and its unique site conditions, seepage may go through, underneath, or around the dam. When left unchecked, excessive seepage can lead to problems such as internal erosion and eventual failure of either the dam itself or other vital components of the dam. According to the As...") |
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[[Category:Surveillance and Monitoring]] | |||
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Active seepage situation at the toe of a dam. | |||
(Image Source: [https://damfailures.org/lessons-learned/uncontrolled-vegetation-on-and-around-dams-can-hinder-inspection-and-lead-to-serious-structural-damage-significant-maintenance-costs-and-possible-failure/ DamFailures.org]) | |||
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Nearly every dam experiences seepage to varying degrees. Depending on the type of dam and its unique site conditions, seepage may go through, underneath, or around the dam. When left unchecked, excessive seepage can lead to problems such as internal erosion and eventual failure of either the dam itself or other vital components of the dam. According to the Association of State Dam Safety Officials (ASDSO), the second most common dam failure incident driver between the years 2010 through 2019 was seepage or internal erosion.<ref name="ASDSO">[https://damsafety.org/dam-failures Dam Failures and Incidents, ASDSO, 2022]</ref> | |||
“Seepage collection and discharge systems, including structural drainage systems, must include access points. Construct these systems in a manner that permits inspection and cleanout of drainpipes. Collection systems should include sediment traps and seepage measurement devices such as weirs or flumes, unless excluding these features is justified in design documentation”.<ref name="Earth Dams and Reservoirs">[[ | As a result, monitoring the level of seepage experienced by a dam is essential to building a performance history of the dam season to season and year to year against which future observations can be compared. Should anomalies in the real-time seepage data occur, having a well-documented history can help operators, owners, and engineers determine the cause of these anomalies and if they are cause for concern. | ||
“If uncontrolled seepage is observed, then it should be monitored. To monitor seepage, the following should be recorded: the location of all seepage exit points; seepage flow rates and clarity; the occurrence of recent [[precipitation]] that could account for what appears to be seepage, or that could affect the appearance and quantity of actual seepage; the level of the reservoir at the time of the observation. Notes, sketches, and photographs are useful in documenting and evaluating seepage conditions. The amount of seepage usually correlates with the level of the reservoir. Generally, as the level of the reservoir rises, the seepage flow rate increases. An increase in a seepage flow rate for a similar reservoir elevation is cause for concern. In some cases, dye can be used to confirm that the reservoir is the source of seepage. A dye test is not a routing procedure. The length of time it takes to conduct a test may vary since the dye may take different amounts of time to penetrate the embankment or foundation. In most cases, records of seepage volumes that correlate with reservoir elevations are needed to show that seepage comes from the reservoir”.<ref name="IED">[[Inspection of Embankment Dams | Inspection of Embankment Dams, USBR]]</ref> | |||
“Seepage collection and discharge systems, including [[structural]] drainage systems, must include access points. Construct these systems in a manner that permits inspection and cleanout of drainpipes. Collection systems should include sediment traps and seepage measurement devices such as weirs or [[flumes]], unless excluding these features is justified in design documentation”.<ref name="Earth Dams and [[Reservoirs]]">[[Technical Release 210-60: Earth Dams and Reservoirs | TR 210-60 Earth Dams and Reservoirs, NRCS, 2019]]</ref> | |||
==Measurement Devices== | |||
*[[Weirs]] | |||
*[[Flumes]] | |||
*[[Piezometers]] | |||
*[[Relief Wells]] | |||
*[[Embankment Drains]] | |||
*[[Concrete Structure Drains]] | |||
*[[Turbidity (Migration of Fines)]] | |||
*[[Visual Surveillance & Monitoring]] | |||
==Best Practices Resources== | ==Best Practices Resources== | ||
{{Document Icon}} | {{Document Icon}} [[Instrumentation of Embankment Dams and Levees (EM 1110-2-1908)|Instrumentation of Embankment Dams and Levees (EM 1110-2-1908) (U.S. Army Corps of Engineers)]] | ||
{{Document Icon}} [[Evaluation and Monitoring of Seepage and Internal Erosion (FEMA P-1032)|Evaluation and Monitoring of Seepage and Internal Erosion (Federal Emergency Management Agency)]] | |||
{{Document Icon}} [[Engineering Guidelines for the Evaluation of Hydropower Projects: Chapter 9- Instrumentation and Monitoring|Engineering Guidelines for the Evaluation of Hydropower Projects: Chapter 9- Instrumentation and Monitoring (Federal Energy Regulatory Commission)]] | |||
{{Document Icon}} [[Design Standards No. 13: Embankment Dams (Ch. 8: Seepage)|Design Standards No. 13: Embankment Dams (Ch. 8: Seepage) (Bureau of Reclamation)]] | |||
==Trainings== | ==Trainings== | ||
{{Video Icon}} | {{Video Icon}} [[On-Demand Webinar: Internal Erosion – Applying Erosion Mechanics From ICOLD Bulletin 164 In Internal Erosion Failure Mode Analyses]] | ||
{{Video Icon}} [[On-Demand Webinar: Relearning How to Look at Piezometric Data for Seepage Evaluation]] | |||
{{Video Icon}} [[On-Demand Webinar: Evaluation and Maintenance of Piezometers, Relief Wells, and Drains in Dams and Levees]] | |||
{{Video Icon}} [[On-Demand Webinar: Seepage Monitoring and Analysis of Embankment Dams]] | |||
{{Video Icon}} [https://youtu.be/jZ3088fsl_Y YouTube: Seepage Monitoring and Analysis of Embankment Dams] | |||
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Latest revision as of 20:15, 18 July 2023
|
| Active seepage situation at the toe of a dam.
(Image Source: DamFailures.org) |
Nearly every dam experiences seepage to varying degrees. Depending on the type of dam and its unique site conditions, seepage may go through, underneath, or around the dam. When left unchecked, excessive seepage can lead to problems such as internal erosion and eventual failure of either the dam itself or other vital components of the dam. According to the Association of State Dam Safety Officials (ASDSO), the second most common dam failure incident driver between the years 2010 through 2019 was seepage or internal erosion.[1]
As a result, monitoring the level of seepage experienced by a dam is essential to building a performance history of the dam season to season and year to year against which future observations can be compared. Should anomalies in the real-time seepage data occur, having a well-documented history can help operators, owners, and engineers determine the cause of these anomalies and if they are cause for concern.
“If uncontrolled seepage is observed, then it should be monitored. To monitor seepage, the following should be recorded: the location of all seepage exit points; seepage flow rates and clarity; the occurrence of recent precipitation that could account for what appears to be seepage, or that could affect the appearance and quantity of actual seepage; the level of the reservoir at the time of the observation. Notes, sketches, and photographs are useful in documenting and evaluating seepage conditions. The amount of seepage usually correlates with the level of the reservoir. Generally, as the level of the reservoir rises, the seepage flow rate increases. An increase in a seepage flow rate for a similar reservoir elevation is cause for concern. In some cases, dye can be used to confirm that the reservoir is the source of seepage. A dye test is not a routing procedure. The length of time it takes to conduct a test may vary since the dye may take different amounts of time to penetrate the embankment or foundation. In most cases, records of seepage volumes that correlate with reservoir elevations are needed to show that seepage comes from the reservoir”.[2]
“Seepage collection and discharge systems, including structural drainage systems, must include access points. Construct these systems in a manner that permits inspection and cleanout of drainpipes. Collection systems should include sediment traps and seepage measurement devices such as weirs or flumes, unless excluding these features is justified in design documentation”.[3]
Measurement Devices
- Weirs
- Flumes
- Piezometers
- Relief Wells
- Embankment Drains
- Concrete Structure Drains
- Turbidity (Migration of Fines)
- Visual Surveillance & Monitoring
Best Practices Resources
Instrumentation of Embankment Dams and Levees (EM 1110-2-1908) (U.S. Army Corps of Engineers)
Evaluation and Monitoring of Seepage and Internal Erosion (Federal Emergency Management Agency)
Design Standards No. 13: Embankment Dams (Ch. 8: Seepage) (Bureau of Reclamation)
Trainings
On-Demand Webinar: Relearning How to Look at Piezometric Data for Seepage Evaluation
On-Demand Webinar: Seepage Monitoring and Analysis of Embankment Dams
YouTube: Seepage Monitoring and Analysis of Embankment Dams
Citations:
Revision ID: 7290
Revision Date: 07/18/2023