Inspections: Difference between revisions

Latest revision as of 17:47, 19 July 2023

Inspection of Oroville Dam's spillway.

(Image Source: Wikimedia)

“Inspections of dams are necessary to ensure that they are functioning properly and safely. Inspections shall accomplish the following:^[1]

"Assess performance of the dam;
"Determine compliance with the O&M Plan;
"Assess the adequacy of previous O&M activities;
"Identify O&M needs;
"Identify conditions that may threaten life and property;
"Identify any changed conditions that may affect the hazard classification; and
"Develop a schedule to address O&M needs”.^[1]

“Dams are built on the ground of materials extracted, in one form or another, from the ground; nature does not create a perfect dam site; there are always imperfections or areas of potential trouble. Identifying every such imperfection is not always possible no matter how extensive and thorough an investigation is made. However, limiting the potential for dam failures is possible: in design … in construction … and, perhaps most important of all, during operation, by inspections assessing both how actual performance compares with the designer’s prediction of performance and whether there are any trends indicating that adverse changes are occurring with time." ^[2]

“As the term ‘periodic inspection’ implies, evaluation of the safety of a dam and its appurtenant works is a never-ending process. While detailed onetime investigations that involve drilling, testing, and analysis are important and can provide much information that is necessary to help assess dam adequacy, they cannot be wholly conclusive by themselves, nor are the conclusions drawn necessarily valid for all time. As noted above, ensuring that one knows everything about an existing structure and its foundation is never possible; therefore, observation and evaluation of continuing performance are essential to help close the gaps in this knowledge”.^[2]

“Furthermore, the condition of a dam or its foundation can change with time, due either to a natural ‘aging’ process or to the effects of such outside influences as earthquakes, long-term impoundment, or extreme weather variations. Again, observation and evaluation of continuing performance can provide the clues that something is taking place that requires further investigation and may require correction. Thus, field examinations, record reviews, the provision of additional data when required, and periodic reevaluation assume a paramount role in maintaining dam safety”.^[2]

Types of Inspection

There are many different types of dam inspections including:

The specific requirements associated with each of these types of inspections may differ based upon regulatory jurisdiction of the dam.

Best Practices Resources

Pocket Safety Guide for Dams and Impoundments, FEMA

Technical Manual: Conduits through Embankment Dams, FEMA

Trainings

Dam Owner Academy: Dam Inspections

YouTube: Introduction to Inspecting Dams for Owners and Operators

On-Demand Webinar: Low-Level Conduits – What Can Go Wrong, How to Inspect, How to Repair?

Technical Seminar: Inspection and Assessment of Dams

Citations:

Revision ID: 7326
Revision Date: 07/19/2023

[NOMM-1] 1.0 ^1.1 National Operation and Maintenance Manual: For Conservation Practices Installed with NRCS Assistance, NRCS, 2003

[EM_7570-2] 2.0 ^2.1 ^2.2 EM 7570 Guide for Safety Evaluation and Periodic Inspection of Existing Dams, NRCS, 1980

[1]

[2]

@@ Line 2: / Line 2: @@
 [[Category:Surveillance and Monitoring]]
 ----
+{{Picture
+<!-- Add image file name (ex.image.jpg) -->
+|image= Oroville_Dam_spillway.jpg
+<!--Add link if applicable -->
+|link=
+<!-- Add picture caption -->
+|caption= Inspection of Oroville Dam's spillway.
+(Image Source: [https://commons.wikimedia.org/wiki/File:Oroville_Dam_concrete_reinforcement_of_emergency_spillway.jpg Wikimedia])
+}}
 <!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->
 “Inspections of dams are necessary to ensure that they are functioning properly and safely. Inspections shall accomplish the following:<ref name="NOMM">[[National Operation and Maintenance Manual: For Conservation Practices Installed with NRCS Assistance | National Operation and Maintenance Manual: For Conservation Practices Installed with NRCS Assistance, NRCS, 2003]]</ref>
-*"Assess performance of the dam;
-*"Determine compliance with the O&M Plan;
+* "Assess performance of the dam;
-*"Assess the adequacy of previous O&M activities;
+* "Determine compliance with the O&M Plan;
-*"Identify O&M needs;
+* "Assess the adequacy of previous O&M activities;
-*"Identify conditions that may threaten life and property;
+* "Identify O&M needs;
-*"Identify any changed conditions that may affect the hazard classification; and
+* "Identify conditions that may threaten life and property;
-*"Develop a schedule to address O&M needs”.<ref name="NOMM" />
+* "Identify any changed conditions that may affect the hazard classification; and
+* "Develop a schedule to address O&M needs”.<ref name="NOMM" />
 “Dams are built on the ground of materials extracted, in one form or another, from the ground; nature does not create a perfect dam site; there are always imperfections or areas of potential trouble. Identifying every such imperfection is not always possible no matter how extensive and thorough an investigation is made. However, limiting the potential for dam failures is possible: in design … in [[construction]] … and, perhaps most important of all, during [[operation]], by inspections assessing both how actual performance compares with the designer’s prediction of performance and whether there are any trends indicating that adverse changes are occurring with time." <ref name="EM 7570">[[Guide for Safety Evaluation and Periodic Inspection of Existing Dams (EM 7570) | EM 7570 Guide for Safety Evaluation and Periodic Inspection of Existing Dams, NRCS, 1980]]</ref>
@@ Line 20: / Line 31: @@
 ==Types of Inspection==
 There are many different types of dam inspections including:
-*[[Technical Inspection]]
+* [[Technical Inspection]]
-*[[Emergency Inspection]]
+* [[Emergency Inspection]]
-*[[Owner Inspection]]
+* [[Owner Inspection]]
-*[[Comprehensive Evaluation]]
+* [[Comprehensive Evaluation]]
-*[[Conduit Inspection]]
+* [[Conduit Inspection]]
-*[[Confined Space Entry]]
+* [[Confined Space Entry]]
-*[[Remotely Operated Vehicle Inspection]]
+* [[Remotely Operated Vehicle Inspection]]
 The specific requirements associated with each of these types of inspections may differ based upon regulatory jurisdiction of the dam.
-==Best Practices Resources==
+<noautolinks>==Best Practices Resources==</noautolinks>
-{{Document Icon}} [[Pocket Safety Guide for Dams and Impoundments (FEMA P-911)|Pocket Safety Guide for Dams and Impoundments (Federal Emergency Management Agency)]]
+{{Document Icon}} [[Pocket Safety Guide for Dams and Impoundments (FEMA P-911) | Pocket Safety Guide for Dams and Impoundments, FEMA]]
-{{Document Icon}} [[Technical Manual: Conduits through Embankment Dams (FEMA P-484)|Technical Manual: Conduits through Embankment Dams (Federal Emergency Management Agency)]]
+{{Document Icon}} [[Technical Manual: Conduits through Embankment Dams (FEMA P-484) | Technical Manual: Conduits through Embankment Dams, FEMA]]
 ==Trainings==
 {{Video Icon}} [https://youtu.be/lIvGH5bux5Q Dam Owner Academy: Dam Inspections]
 {{Video Icon}} [https://youtu.be/kLocKA27hrg YouTube: Introduction to Inspecting Dams for Owners and Operators]
 {{Video Icon}} [[On-Demand Webinar: Low-Level Conduits – What Can Go Wrong, How to Inspect, How to Repair?]]
+{{Website Icon}} [[Technical Seminar: Inspection and Assessment of Dams]]
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