Inspection, Maintenance and Operation of Dams in Pennsylvania
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Inspection, Maintenance And Operation Of Dams In Pennsylvania COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION Office Of Water Management Bureau Of Waterways Engineering And Wetlands Division Of Dam Safety G1354-Mar13 PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION DIVISION OF DAM SAFETY THE INSPECTION, MAINTENANCE AND OPERATION OF DAMS IN PENNSYLVANIA 2009 Edition Reprinted 2013 Original Edition (1985) Prepared by Karl H. Lewis, Ph.D Daniel L. Bink, P.E. Lois M. Muller Department of Civil Engineering University of Pittsburgh PREFACE This publication has been issued by the Pennsylvania Department of Environmental Protection (PA-DEP), Division of Dam Safety for use by owners and operators of dams throughout the state. Its purpose is to provide guidelines for inspection, maintenance and operation of these facilities. It is intended to serve as an information resource and an educational tool for the dam owner/operator. Familiarity with the information contained herein should help the dam owner/operator comply with his responsibilities as established in the Dam Safety and Encroachments Act (32 P.S. §§693.1-693.27). This manual will aid the dam owner/operator in developing adequate skills of observation and inspection and increase his awareness of the elements of proper operation and maintenance. Proper use of this manual should reduce the potential for dam failure and increase the overall safety of a dam by improving operating reliability and maintenance. However, it is recognized that every dam is unique and that this manual does not cover every feature of every possible condition which may develop. Consequently, it should never be considered a substitute for the sound judgment of a qualified professional engineer. This publication is to be viewed as a supplement to, but not a substitute for, any of the provisions of the Dam Safety and Encroachments Act (hereafter referred to as the "Act") or Pennsylvania's dam safety regulations contained in the publication entitled Chapter 105, Rules and Regulations, Dam Safety and Waterway Management (hereafter referred to as "Chapter 105"). It is recommended that the dam owner/operator place this manual in a three-ring binder notebook with sufficient excess capacity to allow for the inclusion of additional future information. The extra space in the notebook can be filled by such items as past inspection reports; operation and maintenance; design and/or construction records; correspondence; and other information pertinent to the dam. This should provide the minimum means whereby owners can keep accurate and up-to-date records of their dams. -i- TABLE OF CONTENTS Page PREFACE .................................................................................................................................................... i TABLE OF CONTENTS ............................................................................................................................... ii ACKNOWLEDGEMENTS ........................................................................................................................... v LIST OF TABLES ........................................................................................................................................ vi LIST OF FIGURES ..................................................................................................................................... vii SECTION 1.0 — BACKGROUND ............................................................................................................... 1 1.1 INTRODUCTION ............................................................................................................................ 2 1.2 COMMON DAM ELEMENTS ......................................................................................................... 2 1.3 TYPES OF FAILURES ................................................................................................................... 3 a. Hydraulic ........................................................................................................................... 3 b. Seepage ............................................................................................................................. 3 c. Structural ........................................................................................................................... 4 1.4 MONITORING DEVICES ............................................................................................................... 4 SECTION 2.0 — DAM INSPECTION ......................................................................................................... 7 2.1 GENERAL ...................................................................................................................................... 8 a. Introduction ....................................................................................................................... 8 b. Pennsylvania Inspection Requirements ............................................................................ 8 c. Inspection Preparation ...................................................................................................... 9 1. Review Existing Data ........................................................................................... 9 2. Gather Appropriate Inspection Equipment ............................................................ 9 a) Required equipment ................................................................................ 9 b) Recommended equipment .................................................................... 10 3. Follow A Predetermined Inspection Sequence ................................................... 11 2.2 INSPECTION ITEMS ................................................................................................................... 11 a. Embankment ................................................................................................................... 12 1. Crest ................................................................................................................... 14 2. Upstream Slope .................................................................................................. 16 3. Downstream Slope ............................................................................................. 18 4. Abutments and Foundations .............................................................................. 20 b. Spillway ............................................................................................................................ 21 1. Erodible Channels ............................................................................................... 21 2. Non-erodible Channels ....................................................................................... 22 c. Outlet Works ................................................................................................................... 24 d. Miscellaneous ................................................................................................................. 27 1. Reservoir ............................................................................................................. 27 2. Monitoring Devices ............................................................................................. 27 3. Metalwork ........................................................................................................... 28 4. Concrete and Concrete Dams ........................................................................... 28 2.3 RECORDS .................................................................................................................................... 31 a. Inspection Checklists ...................................................................................................... 31 b. Photographs .................................................................................................................... 31 c. Monitoring Data ................................................................................................................ 31 - ii - TABLE OF CONTENTS (Continued) Page SECTION 3.0 — DAM MAINTENANCE ................................................................................................... 3.1 INTRODUCTION........................................................................................................................... 3.2 AREAS OF REQUIRED MAINTENANCE .................................................................................... a. Embankment ................................................................................................................... b. Spillway ............................................................................................................................ c. Outlet Conduit .................................................................................................................. d. Miscellaneous ................................................................................................................. 3.3 MAINTENANCE ITEMS ............................................................................................................... a. Vegetation Control ........................................................................................................... b. Rodent Control ................................................................................................................. c. Earthwork ........................................................................................................................ d. Concrete .......................................................................................................................... e. Conduits (Outlet and Spillway) ........................................................................................ 1. Internal Maintenance .......................................................................................... 2. Trash Racks ....................................................................................................... f. Mechanical ...................................................................................................................... g. Electrical .......................................................................................................................... h. Hydraulic ......................................................................................................................... i. Miscellaneous ................................................................................................................. 1. Access Roads .................................................................................................... 2. Monitoring Devices ............................................................................................. 3. Winterizing .......................................................................................................... 4. Vandalism Prevention ......................................................................................... 3.4 MAINTENANCE SCHEDULE ...................................................................................................... 3.5 MAINTENANCE RECORDS ........................................................................................................ SECTION 4.0 — DAM OPERATION ........................................................................................................ 4.1 GENERAL .................................................................................................................................... a. Introduction ..................................................................................................................... b. Elements of an Operation Plan ........................................................................................ 4.2 OPERATION PLAN ...................................................................................................................... a. Section I — Background Data ......................................................................................... 1. Vital Dam Statistics ............................................................................................ a) Embankment .......................................................................................... b) Spillway .................................................................................................. c) Outlet ..................................................................................................... 2. Descriptions of Appurtenances ........................................................................... 3. Operating Instructions for Operable Mechanisms .............................................. 4. Monitoring Instructions and Forms ..................................................................... 5. Maintenance Instructions .................................................................................... 6. Information Bibliography ..................................................................................... 7. Telephone List .................................................................................................... b. Section II — Schedule of Routine Tasks ......................................................................... 1. Category 1 High Hazard Dams ........................................................................... 2. Category 2 High Hazard Dams ........................................................................... - iii - 32 33 33 33 33 34 34 34 34 34 36 36 36 36 36 36 37 37 38 38 38 39 39 39 39 40 41 41 41 41 41 41 41 41 42 42 42 42 42 42 42 42 43 43 TABLE OF CONTENTS (Continued) Page c. 3. All Non-High Hazard Category 3 and Category 4 Dams .................................... 43 Section III — Emergency Action Plan ............................................................................. 43 APPENDIX A IMPORTANT TELEPHONE NUMBERS AND ADDRESSES .......................................... 47 APPENDIX B INSPECTION CHECKLIST .............................................................................................. 51 APPENDIX C REFERENCE LIST .......................................................................................................... 61 APPENDIX D GLOSSARY OF TERMS .................................................................................................. 64 APPENDIX E SUBJECT INDEX ............................................................................................................. 72 - iv - ACKNOWLEDGEMENTS (Original Edition, 1985) Failures or near failures of several dams in the United States in recent years have resulted in an increased emphasis on dam safety. Tragedies such as the collapse of the Buffalo Creek coal waste embankment in West Virginia and the failure of the Canyon Lake Dam in South Dakota, both of which occurred in 1972, led to the enactment of the National Dam Inspection Act of 1972 (P. L 92-367). Failure of the Teton Dam in 1976 and Laurel Run Dam (Pennsylvania) and Toccoa Falls Dam (Georgia) in 1977 resulted in the implementation of this statute by the federal government. The U. S. Army Corps of Engineers in cooperation with the Department of Environmental Protection (DEP) completed an intensive four-year inspection program including several hundred existing dams in the state. In 1978, the Pennsylvania Legislature enacted the Dam Safety and Encroachments Act (Act No. 325, P.L. 1375). This statute was amended by Act No. 70 in 1979. In September, 1980, the Environmental Quality Board adopted Chapter 105, Rules and Regulations, Dam Safety and Waterway Management. The assistance and training provided by the Corps of Engineers during the four-year period of the National Dam Inspection Program has been an invaluable asset in development the commonwealth's dam safety program. The experiences of other states, particularly Virginia, Ohio and Colorado have been utilized in the development of this publication. The Bureau of Reclamation has also contributed many valuable ideas through its Safety Evaluation of Existing Dams program. It is noted that the cooperation of the owners of dams within the state is the keystone to the success of the state's dam safety program. The response of most of the owners, both public and private, with whom the Division of Dam Safety has come in contact as a result of the Inspection Program has been satisfying. The ultimate purpose of such a program is the protection of the lives and property of the citizens of the state. The ready acceptance of this goal by the majority of the wide range of individuals and groups bearing the responsibility for the safety of dams is very much appreciated. The information contained in this effort was collected and prepared by Daniel L. Bonk, P. E., and Lois M. Muller, under the direction of Karl H. Lewis of the University of Pittsburgh. Administrative facilities and assistance were provided by GAI Consultants, Inc. of Monroeville, Pennsylvania. Overall preparation and editing was performed under the general direction of Joseph J. Ellam, Chief, Division of Dam Safety. The Division of Dam Safety extends its gratitude and appreciation to all the above for their efforts and assistance. -v- LIST OF TABLES Table Title/Description Page 1.0 Common Monitoring Devices ............................................................................................. 5 2.0 Probable Causes of Embankment Conditions .................................................................. 12 2.1 Possible Harmful Effects of Embankment Conditions ...................................................... 13 2.2 Recommended Actions for Embankment Conditions ...................................................... 13 3.0 Rodents and Rodent Controls ......................................................................................... 35 3.1 Mechanical Maintenance Procedures .............................................................................. 37 - vi - LIST OF FIGURES Figure Title/Description Page 1 Common Dam Elements ................................................................................................. 2 2 3 4 Survey Monuments .......................................................................................................... 5 Inclinometer ...................................................................................................................... 5 Longitudinal and/or Transverse Cracks along Embankment Crest ............................... 14 5 6 Low Area in Dam Crest ................................................................................................. 15 Sinkhole or Animal Burrow Along Embankment Crest ................................................... 15 7 8 9 Erosion Behind Poorly Graded Riprap ........................................................................... 16 Whirlpool in Reservoir ................................................................................................... 17 Erosion at Embankment-Abutment Contact (Upstream Slope) ..................................... 17 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Wet Areas (no measurable flow) .................................................................................... Erosion at Embankment-Abutment Contact (Downstream Slope) ................................ Bulging ........................................................................................................................... Seepage Water Exiting as a Boil in the Foundation ...................................................... Trampoline Effect in Large Soggy Area ........................................................................ Leakage from Abutments Beyond the Dam .................................................................. Slide, Slough or Scarp in Spillway Channel .................................................................. Erosion in Spillway Channel .......................................................................................... Excessive Vegetation or Debris in Erodible Spillway Channel ..................................... Spillway Wall Displacement or Misalignment ................................................................ Open or Displaced Spillway Wall Joints ......................................................................... Excessive Vegetation or Debris in Non-Erodible Spillway Channel .............................. Outlet Pipe Damage ....................................................................................................... Debris Under Outlet Gate ............................................................................................... Cracked Outlet Gate Leaf .............................................................................................. Damaged Outlet Gate Seat or Guides .......................................................................... Damage to Outlet Control Works .................................................................................. Discharges from Outlet Eroding Toe of Dam ................................................................. Deterioration at Outlet Discharge Structure .................................................................. 18 19 19 20 20 20 21 21 22 22 22 23 24 24 24 24 25 26 26 29 30 31 32 Inoperable or Damaged Instrumentation ....................................................................... Longitudinal or Horizontal Concrete Cracking................................................................ Transverse or Vertical Concrete Cracking .................................................................... Diagonal Concrete Cracking ......................................................................................... 27 28 29 29 33 34 35 36 Random Concrete Cracking ........................................................................................... Pattern Concrete Cracking ............................................................................................. Leakage through Concrete Joints or Cracks ................................................................. Monolith Misalignment ................................................................................................... 29 29 30 30 - vii - SECTION 1.0 BACKGROUND -1- SECTION 1.0 — BACKGROUND 1.1 Introduction Water stored behind a dam represents potential energy which can create a hazard to life and property located downstream. At all times the risks associated with the storage of water must be minimized. Dams must be properly designed, constructed, operated, and maintained to safely fulfill their intended function. The assessment of the safety of a dam must be a continuing effort requiring periodic safety examinations and evaluations throughout the life of the structure. The Division of Dam Safety recommends that relative risk and hazard factors determined using the storage capacity of the reservoir; type of dam; height, age and general condition of the dam; and present and anticipated downstream populations and development be used in establishing the frequency of onsite inspections. The frequency of these onsite inspections of a specific dam, once established, should be updated as the above factors change. Based on the high priority placed on previously identified deficiencies, some dams will require regular examinations on a more frequent basis than others. The purpose of a safety evaluation is to determine the status of a dam relative to its structural and operational safety. The evaluation should identify problems and recommend either remedial repairs, operational restrictions and/or modifications, or analyses and studies to determine solutions to the problems. A minimum prerequisite for any dam owner/operator who desires a better understanding of dams and dam safety is familiarity with the following: Basic terminology and common dam elements Means by which dams fail Devices with which dams can be monitored The remainder of the information contained in Section 1.0 of this manual, along with the Glossary of Terms contained in Appendix D, is intended to cover the items described above. 1.2 Common Dam Elements The common elements of a typical dam are illustrated in the figure below. FIGURE 1 -2- 1.3 Types of Failures Dam failures are usually the result of either poor design, improper construction, improper operation, inadequate maintenance, or a combination of these factors. The manner in which a dam fails and the particular causes of failure are usually varied, multiple, complex and interrelated. However, failure modes may be divided into the following three general categories: a) hydraulic failures; b) seepage failures; and c) structural failures. These failure modes are defined below. a. Hydraulic. Hydraulic failures are those resulting from the erosive action of the uncontrolled flow of water adjacent to the dam and its foundation. Earth dams are particularly susceptible to hydraulic failure since earth erodes when subjected to flows at relatively low gradients. b. Seepage. Seepage must be controlled in velocity and amount. Seepage may occur both through the dam as well as under and around the dam in the foundation and abutment materials. Seepage, if uncontrolled, can erode material starting at the downstream slope or foundation and working back toward the upstream slope to form a "pipe" which often leads to a complete failure of the structure. This phenomenon, known as "piping", is defined as the progressive development of internal erosion. It can also contribute to destabilizing movements of the embankment such as slides or sloughs. -3- c. Structural. Structural failures involve the rupture of the dam and/or its foundation. This is a particularly important hazard on large dams and on dams built of low strength clays, silts and other materials such as slag and fly ash. 1.4 Monitoring Devices Various devices exist that can be used to monitor the physical changes occurring within the dam over time. These devices provide a quantitative measure of the changes. Thus, when used in combination with visual inspections, a more complete assessment of the condition of a dam may be made. The need for monitoring devices during the design and/or the construction phases depends upon the hazard potential classification of the dam. During the life of a dam, as changes occur, it may become necessary to add one or more types of monitoring devices. The types of monitoring devices required and their location should be determined by a qualified professional engineer, and be in compliance with Division of Dam Safety requirements. The installation of instrumentation after a dam has been in operation is usually in response to a need for data to assess the safety of the dam, stemming from concern about conditions observed during a visual inspection. The Division of Dam Safety may require installation of monitoring devices based upon its own evaluation of the annual inspection reports submitted by the owner's engineer. The more common monitoring devices are presented in Table 1.0. For easy reference the remainder of this manual has been divided into three main sections as follows: Section 2.0 Dam Inspection - This section provides step-by-step procedures for dam inspections. Included are: 1) a checklist of equipment recommended for an efficient and thorough inspection of the facility; 2) a recommended inspection sequence; and 3) a partial list of problems and conditions that may be observed during a typical dam inspection. Section 3.0 Dam Maintenance - This section covers the areas of required maintenance for a typical dam. Included are discussions of various specific maintenance items along with a recommended maintenance schedule. Section 4.0 Dam Operation - This section provides guidelines for the development of an adequate operation plan. In addition, the section defines the basic elements of an effective emergency warning system including a surveillance and warning plan, and an evacuation plan. Finally, an index is provided at the back of this manual (see Appendix E) to aid the user in quickly locating any subject matter contained herein. -4- Table 1.0 COMMON MONITORING DEVICES Device 1. Survey Monuments or Permanent Points Purpose Comments Provides set points (to be surveyed during the dam's life) from which the displacements that the dam undergoes may be measured. The monuments should be installed so as to provide enough survey points from which vertical, horizontal, and angul ar dis pl ac em ents m a y b e measured. FIGURE 2 2. Inclinometers Used to monitor internal displacements of the embankment and/or its foundation. The system consists of a special casing with grooves on the inside at the quarter points. The casing is installed in a drilled hole and backfilled with material selected by the engineer. Then an instrument is used to traverse the length of the casing and determine its profile in two perpendicular directions. All readings are compared with the initial profile to determine if changes have occurred. FIGURE 3 3. Observation Wells Used to measure the height of the water surface in the embankment at the location of the well. -5- Observation wells should be installed along the cross section of the dam so as to provide a clear picture of the water surface through the dam, i.e., more than one well across a section should be installed. 4. Weir Measures the quantity of leakage occurring through the embankment and/or foundation. -6- When measurable quantities of flow are occurring through the foundation and/or embankment, a system of drainage ditches should be excavated and the flow from the various seeps collected and diverted into a channel across which the weir has been constructed. The dimensions and the depth of water flowing over it are used to calculate the quantity of flow. SECTION 2.0 DAM INSPECTION -7- SECTION 2.0 — DAM INSPECTION 2.1 General a. Introduction. The purpose of this section is to provide a dam owner/operator with a simple and systematic method for inspecting a dam. Simple because it involves a "learn as you go" procedure. The easy to follow steps allow for any dam owner/operator to custom fit the system to his particular facility. The method emphasizes techniques of observation rather than evaluation, which is more properly the responsibility of experienced professionals. The relationship of a dam to its owner should be, but often is not, similar to the relationship of a home and its owner. Many homeowners do not fully understand the intricacies of home design and construction, or the workings of a particular item like the plumbing. This, similarly, is very often the case for a dam owner/operator. However, by living day after day in his home, the homeowner gains a feel for it. He learns its peculiarities and is aware of unusual developments. Continual observation allows the home owner to recognize a problem and enables him to sense how much time he has before he must make repairs. The dam owner/operator must approach his dam in the same manner. The key is getting to know the facility. The wise dam owner/operator knows his dam well even though he may not thoroughly understand it. He can recognize a physical condition that has changed or is developing. He can sense when equipment is not operating properly. Over time, the dam owner/operator, like the homeowner, gains a feel for the condition of his property. Dam owner/operators, however, must go a step further than homeowners. A homeowner may keep mental notes whereas a dam owner/operator must maintain records. A major problem in a home will likely only affect the lives of the homeowner and his family. Dam problems have the potential to affect the lives of all of the families located in the floodplain downstream. In order to protect himself and his downstream neighbors, the dam owner/operator needs to write down his observations, take photographs, make sketches, and refer to this manual to gain a better understanding of what he sees. Overall the dam owner/operator, in time, learns how to take care of the dam. Through experience he understands how his dam is supposed to appear. Very often the existence of a problem is not as important as the rate of development or change in its condition. Continuous observation and recording of conditions is the best means for maintaining familiarity with the dam. In this way, the dam owner/operator becomes an effective observer and serves to protect himself, his investment, and his downstream neighbors. b. Pennsylvania Inspection Requirements. The owner of a dam in Pennsylvania must inspect the facility at least once every three months according to the rules and regulations contained in Chapter 105 (Reference 22, Appendix C). In addition, all dams with Category 1 or 2 High-Hazard Potential Classification must be inspected annually by a registered professional engineer experienced in dam design, construction and inspection. Annual reports certified by the engineer regarding the condition of the dam must be submitted to the Division of Dam Safety on or before December 31 of each year. More frequent reports may be required by the Division of Dam Safety if, at its discretion, conditions indicate -8- such reports are necessary to assure adequate protection of health, safety and property (see Inspection Checklists in Appendix B). For additional information regarding Dam Safety Regulations in Pennsylvania, see References 21 and 22 identified in Appendix C. c. Inspection Preparation. 1. Review Existing Data. Design reports, construction drawings, correspondence, hand-written notes, photographs, sketches, etc. are likely the most overlooked resource available to a dam owner/operator. These records provide insights into the history of the facility and are often invaluable. The volume of available data varies greatly from dam to dam. Information has often been stored carelessly and, in many cases, has been destroyed by fire or flood. It is important that the dam owner/operator establish an orderly information file on his dam and maintain all available data in a secure location. The Division of Dam Safety maintains data files on all dams that have received permits. It is recommended that dam owners/operators contact the Division of Dam Safety for further information regarding their dams. An important part of the dam inspection method is a thorough review of existing data. Typically the dam owner/operator should review his entire file a day or two prior to the inspection in order to note past conditions, especially the location of previously observed deficiencies. 2. Gather Appropriate Inspection Equipment. The degree of difficulty in performing any task depends a lot on whether or not one is outfitted with the proper equipment and tools. The following are lists of required and recommended inspection equipment. The required items represent equipment pieces without which a proper inspection simply cannot be performed. The recommended items should help the dam inspector achieve even better results. Through experience the inspector will learn what tools he really needs to adequately inspect his facility. a) Required Inspection Equipment: CLIPBOARD and INSPECTION CHECKLIST — Clipboard provides a solid writing surface. Inspection checklist serves as a reminder to inspect all important areas. An example is presented at the end of this section. NOTEBOOK and PENCIL — It is very important to write down observations at the time they are made. This reduces mistakes and the need to return to the area to refresh the inspector's memory. -9- STANDARD SIX-FOOT COLLAPSIBLE RULE — This provides a means for making rough measurements at the dam. Measurements are extremely useful and should be taken whenever possible. b) Recommended Inspection Equipment. CAMERA — Photographs provide a reliable record of observed field conditions. They can be valuable in comparing past and present configurations. An inexpensive model usually takes pictures good enough for inspection records. TAPE RECORDER — This can be utilized to supplement hand-written notes. It allows the inspector to record a greater volume of observations. HANDLEVEL — This is needed to accurately locate areas of interest and to determine embankment heights and slopes. PROBE — A probe can provide information on conditions below the surface, such as the depth and softness of a saturated area. Any stiff light rod with a pointed tip and of sufficient strength to penetrate soil will do. HARD HAT — A hard hat is recommended for inspecting large outlets or working in construction areas. POCKET TAPE — Many descriptions are not accurate enough when estimated, paced, or roughly measured with a six-foot collapsible rule. The pocket tape provides accurate measurements which allow meaningful comparisons to be made. FLASHLIGHT — The interior of an outlet in a small dam can often be inspected adequately without crawling through it by shining a good flashlight or fluorescent light into the outlet and observing conditions. CONTAINER AND TIMER — These are used to make fairly accurate measurements of seepage rates. Establishing the time it takes the seepage flow to fill the container, such as a gallon bucket, enables the inspector to calculate the number of gallons per minute of flow. Various container sizes may be required, depending on the flow rates. STAKES AND FLAGGING TAPE — These are used to mark areas requiring future attention and to stake the limits of existing conditions, such as cracks and wet areas, to allow future comparison. WATERTIGHT BOOTS — These are often required when inspecting various areas of the dam site where standing water is present. SHOVEL — A long-handled shovel is useful in clearing drain outfalls, removing debris and locating monitoring points. ROCK HAMMER — Questionable-looking riprap or concrete can be checked for soundness with a rock hammer. However, care must be taken not to break through thin spots or cause unnecessary damage. BONKER — The condition of support material behind concrete or asphalt faced dams generally cannot be determined by observing the surface of facing alone. Conditions below the surface may be determined by the sound produced when the surface facing material is firmly tapped. Facing material fully supported by fill material produces a "clink" or "bink" sound, whereas facing material that is over a void or hole in the facing produces a "clonk" or "bonk" sound. The bonker can be - 10 - made of 1-inch hardwood dowel with a metal tip firmly affixed to the tapping end. A rubber shoe like those on some furniture legs is recommended for the other end to allow the bonker to be used as a walking aid on steep, slippery slopes. BINOCULARS — These are useful for inspecting limited access areas especially on concrete dams. 3. Follow a Predetermined Inspection Sequence. The purpose of preparing an inspection route in advance is to assure that every part of the dam will be observed. The route is repeated as often as necessary to insure that the inspector has viewed every square foot of the facility. A productive sequence of inspection that has been used with favorable results is as follows: i. CREST — Walk across the crest from abutment to abutment. ii. UPSTREAM SLOPE — Walk across the upstream slope in an up and down or zig-zag pattern from abutment to abutment. iii. DOWNSTREAM SLOPE — Walk across the downstream slope in an up and down or zig-zag pattern from abutment to abutment. iv. EMBANKMENT—ABUTMENT CONTACTS — Walk the entire length of the embankmentabutment contacts. v. OUTLET CONDUIT — Observe all accessible features of the outlet conduit. vi. SPILLWAY — Walk along the entire length of the spillway in a back and forth manner. vii. ABUTMENTS — Traverse abutments in a practical manner so as to gain a general feel for the conditions which exist along the valley sidewalls. viii. DOWNSTREAM CHANNEL — Travel the route of the stream below the dam to maintain familiarity with locations, of residences and property which could be affected by dam failure. ix. RESERVOIR SLOPES — Scout the reservoir perimeter in an effort to develop an overall familiarity with its conditions. Following a specific predetermined route will lessen the chance of overlooking an important condition. Repeating the same route each inspection will aid in the development of consistent records. 2.2 Inspection Items The following section contains a description of the most common deficiencies that might be observed during a dam inspection. The information that follows should not be construed as an all-encompassing last word on the problems which may be encountered. In particular, the probable causes and possible harmful effects that are listed for each condition are not intended to cover all possibilities. If the dam inspector encounters a condition which he feels is not addressed in this section or any condition, the severity of which he questions, he should immediately contact the Division of Dam Safety (refer to telephone numbers listed in Appendix A). - 11 - a. EMBANKMENT. The information contained in this section is organized in a manner intended to allow for easy use and quick reference. Match the condition observed during the embankment inspection with one of the conditions presented in this section. As an example, a typical condition that could be encountered is presented as shown below. Excess Vegetation Probable Causes: 7 (See Table 2.0) Possible Harmful Effects: 10, 11 (See Table 2.1) Recommended Actions: 20, 21 (See Table 2.2) Table 2.0 PROBABLE CAUSES OF EMBANKMENT CONDITIONS 1. Embankment and/or foundation movement. 2. Internal and/or external erosion of material. 3. Soil weakening due to water infiltration. 4. Unusual increase in the loads on the dam (for example, due to: earthquake, high pool level, rapid lowering of pool level, additional dead weight on embankment). 5. Rodent activity. 6. Deterioration due to weathering. 7. Inadequate maintenance. 8. Soil shrinkage due to moisture loss. 9. Improper construction and/or inadequate design. 10. Vehicle traffic. 11. Locally steep slope. 12. Wave action. 13. Vandalism. 14. Developed seepage path reaching external surface. 15. Retained rainfall/snowmelt on surface. 16. Natural seeding. 17. Change in seed type during initial postconstruction seeding. 18. Leaking outlet conduit. - 12 - Table 2.1 POSSIBLE HARMFUL EFFECTS OF EMBANKMENT CONDITIONS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Exposes interior portion of embankment directly to the elements, particularly precipitation, which may lead to a more deteriorated condition. May create a local area of inadequate strength within the embankment which could lead to future movement. May be indicative of unstable conditions. Could lead to failure. Reduces available embankment cross section, thus decreasing resistance to movement. Provides a potential path which may lead to erosive seepage. Reduces available freeboard. Represents an area particularly susceptible to erosion damage which can lead to dam failure. Uncontrolled internal erosion which can lead to dam failure. Could become an area susceptible to local movement if due to wet conditions. Obscures visual observation. Deterioration of roots may leave voids which may lead to erosive seepage. Can lead to rapid erosion of abutment and/or evacuation of the reservoir. Can lead to movement and affect the stability of the dam. Provides an area for water to accumulate which could result in soil softening and create an area of inadequate strength within the embankment. Table 2.2 RECOMMENDED ACTIONS FOR EMBANKMENT CONDITIONS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Photograph condition. Carefully inspect and record the location and physical dimensions of the conditions. Place stakes at the limits of the condition and monitor frequently to detect any changes in observed conditions. If condition was never previously observed, bring condition to the attention of an engineer during the next annual inspection. If condition was observed during a previous inspection and brought to the attention of a qualified engineer, note any changes in its physical dimensions. If condition appears to be unusual or inconsistent with previous observations, immediately contact the Division of Dam Safety. If condition has never been previously observed, contact the Division of Dam Safety immediately for further consultation and possible action. Contact the Division of Dam Safety immediately for further consultation and possible action. Regrade to provide for uniform drainage. Fill low areas with compacted soil. Apply gravel layer or other suitable roadbase to accommodate traffic. Repair erosion if necessary. Replace riprap. Consult a qualified engineer to make recommendations for remedial measures. Repair by replacing eroded material with compacted fill. Apply non-erodible material (rock, concrete, asphalt, etc.) for protection against future erosion. Record flow rate if possible. Frequent measurements or estimates may be necessary if flow rate is changing rapidly. Note any evidence of muddy flow. Post warning signs prohibiting vehicular traffic along slope and/or restrict access. Control excessive brush through regular routine maintenance. Remove large trees under the direction of a qualified engineer. - 13 - EMBANKMENT CREST Thin Random Cracking Longitudinal and/or Transverse Cracks FIGURE 4 Probable Causes: 8 Possible Harmful Effects: 1 Recommended Actions: 1, 2, 3, 4, 5, 6 Probable Causes: 1, 2, 4 Possible Harmful Effects: 1, 2, 5 Recommended Actions: 1, 2, 3, 5, 6, 7 Excessive Vegetation Crest Arching or Bowing Probable Causes: 7 Possible Harmful Effects: 10, 11 Recommended Actions: 20, 21 Probable Causes: 1, 3, 4. Possible Harmful Effects: 3 Recommended Actions: 1, 2, 3, 5, 6, 7 - 14 - EMBANKMENT CREST Low Area in Dam Crest Sinkhole or Animal Burrow FIGURE 5 FIGURE 6 Probable Causes: 1, 2, 9 Possible Harmful Effects: 3, 7, 14 Recommended Actions: 1, 2, 3, 5, 6, 7 Probable Causes: 2, 5 Possible Harmful Effects: 1, 3 Recommended Actions: 1, 2, 3, 5, 6, 7 Ruts or Puddling on Dam Crest Probable Causes: 7, 9, 10 Possible Harmful Effects: 1, 7, 14 Recommended Actions: 9, 10, 11 - 15 - UPSTREAM EMBANKMENT SLOPE Slide, Slough, or Scarp Broken Down or Missing Riprap Probable Causes: 1, 3, 4, 11, 12 Possible Harmful Effects: 1, 3, 4 Recommended Actions: 1, 2, 3, 5, 6, 7 Probable Causes: 11, 12, 13 Possible Harmful Effects: 7 Recommended Actions: 1, 12, 13 Erosion Behind Poorly Graded Riprap Deteriorated Slope Protection (concrete, asphalt, other material) FIGURE 7 Probable Causes: 12 Possible Harmful Effects: 7 Recommended Actions: 1, 14 Probable Causes: 6, 9, 12 Possible Harmful Effects: 7 Recommended Actions: 1, 14 - 16 - UPSTREAM EMBANKMENT SLOPE Sinkhole or Animal Burrow Whirlpool in Reservoir FIGURE 8 Probable Causes: 2, 5 Possible Harmful Effects: 1, 3 Recommended Actions: 1, 2, 3, 5, 6, 7 Probable Causes: 2, 18 Possible Harmful Effects: 3, 8 Recommended Actions: 1, 8 Erosion at Embankment-Abutment Contact Excessive Vegetation FIGURE 9 Probable Causes: 9 Possible Harmful Effects: 7 Recommended Actions: 1, 15, 16 Probable Causes: 7 Possible Harmful Effects: 10, 11 Recommended Actions: 20, 21 - 17 - DOWNSTREAM EMBANKMENT SLOPE Clear Seepage Muddy Seepage Probable Causes: 14 Possible Harmful Effects: 2, 8 Recommended Actions: 1, 2, 3, 5, 6, 7, 17, 18 Probable Causes: 2, 14 Possible Harmful Effects: 2, 3, 8 Recommended Actions: 1, 2, 3, 8, 17 Wet Areas (no measurable flow) Marked Change in Vegetation FIGURE 10 Probable Causes: 14, 15 Possible Harmful Effects: 3 Recommended Actions: 1, 2, 3, 5, 6, 7 Probable Causes: 14, 15, 16, 17 Possible Harmful Effects: 9 Recommended Actions: 1, 2, 3, 5, 6, 7 - 18 - DOWNSTREAM EMBANKMENT SLOPE Sinkhole or Animal Burrow Slide, Slough, or Scarp Probable Causes: 2, 5 Possible Harmful Effects: 1, 3 Recommended Actions: 1, 2, 3, 5, 6, 7 Probable Causes: 1, 3, 4, 11 Possible Harmful Effects: 1, 3, 4, 7 Recommended Actions: 1, 2, 3, 5, 6, 7 Erosion at Embankment-Abutment Contact Bulging FIGURE 11 FIGURE 12 Probable Causes: 9 Possible Harmful Effects: 7 Recommended Actions: 1, 15, 16 Probable Causes: 1 Possible Harmful Effects: 3 Recommended Actions: 1, 2, 3, 5, 6, 7 - 19 - DOWNSTREAM EMBANKMENT SLOPE Erosion Excessive Vegetation Probable Causes: 6, 10 Possible Harmful Effects: 7 Recommended Actions: 1, 15, 19 Probable Causes: 7 Possible Harmful Effects: 10, 11 Recommended Actions: 20, 21 ABUTMENTS AND FOUNDATION Seepage Water Exiting as a Boil in the Foundation Trampoline Effect in Large Soggy Area FIGURE 13 Probable Causes: 2, 14 Possible Harmful Effects: 3, 8 Recommended Actions: 1, 2, 3, 8 FIGURE 14 Probable Causes: 14 Possible Harmful Effects: 3 Recommended Actions: 1, 2, 3, 8 Leakage from Abutments Beyond the Dam Probable Causes: 14 Possible Harmful Effects: 12, 13 Recommended Actions: 1, 2, 3, 5, 6, 7, 17, 18 - 20 - ERODIBLE CHANNELS (Earth or Rock Cuts through Abutment) CONDITION OBSERVED SLIDE, SLOUGH OR SCARP PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECTS RECOMMENDED ACTION PROBABLE CAUSES: 1. Photograph condition. 1. Locally steep side slope. 2. Repair damaged area by replacing eroded material with compacted fill. 2. Discharge flow has eroded toe of slope. POSSIBLE HARMFUL EFFECTS: 1. Reduces open cross section of channel and thereby reduces available spillway discharge capacity. Inadequate spillway capacity can lead to embankment overtopping and result in dam failure. 3. Protect area against future erosion by installing suitable rock riprap. Revegetate area if appropriate. 4. Bring condition to the attention of the engineer during next annual inspection. 2. Unabated erosion in earthen spillways can lead to larger slides within the abutment that can eventually affect the stability of the embankment. FIGURE 16 EROSION CHANNELS PROBABLE CAUSES: 1. Surface runoff from intense rainstorms or flow from spillway carries surface material down the slope, resulting in continuous troughs. 2. Bicycle or livestock traffic create gullies where flow concentrates. POSSIBLE HARMFUL EFFECTS: 1. Unabated erosion can lead to slides, slumps or slips which can result in reduced spillway capacity. Inadequate spillway capacity can lead to embankment overtopping and result in dam failure. 1. Photograph condition. 2. Repair damaged areas by replacing eroded material with compacted fill. 3. Protect areas against future erosion by installing suitable rock riprap. Revegetate area if appropriate. 4. Bring condition to the attention of the engineer during next annual inspection. FIGURE 17 EXCESSIVE VEGETATION OR DEBRIS IN CHANNEL PROBABLE CAUSES: 1. Inadequate maintenance. 2. Deposition of debris after flooding. 1. Provide regular maintenance routine 2. Inspect after flooding events and maintain as required. - 21 - POSSIBLE HARMFUL EFFECTS: 1. Obscures visual observation. 2. Obstructs spillway discharge and reduces available spillway capacity. Inadequate spillway capacity can lead to embankment overtopping and result in dam failure FIGURE 18 NON—ERODIBLE CHANNELS (Lined with Concrete, Asphalt, Masonry, Etc.) CONDITION OBSERVED WALL DISPLACEMENT OR MISALIGNMENT PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECT RECOMMENDED ACTION PROBABLE CAUSES: 1. Poor workmanship construction. 1. Photograph condition. during 2. Uneven settlement of foundation. 2. Contact a qualified engineer for consultation and development of. remedial actions. 3. Excessive earth and water pressure on channel sidewalls. 4. Poor design. FIGURE 19 POSSIBLE HARMFUL EFFECTS: 1. Minor displacement can create eddies and turbulence in the flow, and precipitate erosion and/or wall damage. 2. Major displacement can lead to severe cracks or slab movement and eventually result in failure of the spillway structure. OPEN OR DISPLACED JOINTS PROBABLE CAUSES: 1. Poor workmanship construction. during 2. Excessive and/or uneven settlement of foundation. 3. Sliding of concrete slab. 4. Deteriorated sealant. FIGURE 20 POSSIBLE HARMFUL EFFECTS: 1. Joint openings allow water to enter and erode material beneath the concrete which can lead to weakened foundation support and eventual failure of the spillway structure. - 22 - 1. Photograph condition. 2. Contact a qualified engineer for consultation and development of remedial actions. END OF SPILLWAY CHUTE UNDERCUT PROBABLE CAUSES: 1. Poor design and/or construction. 1. Photograph condition. 2. Inadequate erosion protection. 2. Dewater affected area. Replace eroded material with compacted backfill. Provide suitable rock riprap to protect against future erosion. POSSIBLE HARMFUL EFFECTS: 1. Can lead to extensive undermining of foundation and eventually result in failure of the spillway structure. 2. Unabated erosion can lead to instability of adjacent portions of the embankment. SEEPAGE FROM A CONCRETE JOINT PROBABLE CAUSES: OR CRACK 1. Insufficient or clogged weep holes are causing water collected behind spillway to exit by whatever route available. EXCESSIVE VEGETATION OR DEBRIS IN CHANNEL 3. Contact a qualified engineer for consultation to assess need for additional remedial measures. 1. Photograph condition. 2. Clean all weep holes and drain outfalls. POSSIBLE HARMFUL EFFECTS: 3. Check areas behind walls for ponding of surface water. 1. Excess water pressure can lead to instability of the spillway structure. Failure of the spillway structure can lead to dam failure. 4. If condition persists a qualified engineer should inspect the condition and recommend further actions to be taken. PROBABLE CAUSES: 1. Inadequate maintenance. 2. Deposition of debris after flooding. POSSIBLE HARMFUL EFFECTS: 1. Obscures visual observation. 2. Obstructs spillway discharge and reduces available spillway capacity. Inadequate spillway capacity can lead to embankment overtopping and result in dam failure. FIGURE 21 - 23 - 1. Provide regular maintenance. routine 2. Inspect after flooding events and maintain as required. c. OUTLET WORKS CONDITION OBSERVED OUTLET PIPE DAMAGE PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECTS PROBABLE CAUSES: 1. Settlement foundation. of embankment All Conditions: 1. Photograph condition. 2. Check for evidence of water either entering or exiting pipe at crack/hole/etc. 2. Corrosion (metal pipe). 3. Erosion (concrete pipe). 4. Cavitation 5. Poor design and/or construction. POSSIBLE HARMFUL EFFECTS: 1. Provide opening for flow to exit conduit. Could lead to erosion of embankment materials and result in failure of dam. FIGURE 22 FIGURE 22 VALVE LEAKAGE RECOMMENDED ACTION 3. Repair damage. Outlet conduit should not be used until repairs are completed. If problem is the result of cavitation, discuss possibility of installing an air vent with a qualified engineer. 4. Recheck frequently to insure that repairs have been effective. PROBABLE CAUSES: A. Debris Stuck Under Gate 1. Due to ineffective or damaged trash rack POSSIBLE HARMFUL EFFECTS 1. Raise and lower gate slowly until debris is loosened and floats past valve. When reservoir is lowered, repair or replace trash rack. 1. Gate will not close. Gate or stem may be damaged in effort to close gate. FIGURE 23 PROBABLE CAUSES B. Cracked Gate Leaf 1. Due to ice action, rust, impact, vibration, or stress resulting from attempting to close gate when it is jammed. 1. Use valve only in fully open or closed position. Minimize use of valve until leaf can be repaired or replaced. FIGURE 24 POSSIBLE HARMFUL EFFECTS: 1. Gate leaf may causing rapid reservoir. fail completely drawdown of PROBABLE CAUSES: C. Damaged Gate Seat or Guides FIGURE 25 1. Due to rust, erosion, vibration, or wear. - 24 - cavitation, 1. Minimize use of valve until guides/seats can be repaired. If cavitation appears to be cause check to see if air vent pipe exists and is unobstructed. POSSIBLE HARMFUL EFFECTS: 1. Leakage and loss of support for gate leaf. 2. Gate may bind in guides and become inoperable. DAMAGE TO CONTROL WORKS PROBABLE CAUSES: A. Broken Block Support 1. Concrete deterioration 2. Excessive force exerted on control stem by attempting to open gate when it was jammed. B. Bent/Broken Control Stem 1. Rust. 2. Excess force used to open or close gate. 3. Excessive ice pressures. FIGURE 26 C. Broken/Missing Stem Guides 1. Rust. 2. Inadequate lubrication 3. Excess force used to open or close gate when it was jammed. POSSIBLE HARMFUL EFFECTS A. Broken Block Support 1. Causes control support block to tilt; control stem may bind. 2. Control headworks may settle. 3. Gate may not open all the way. 4. Support block may fail completely leaving outlet inoperable. B. Bent/Broken Control Stem. 1. Outlet is inoperable. C. Broken/Missing Stem Guides 1. Loss of support for control stem. Stem may buckle and break under normal use. - 25 - 1. Photograph condition. 2. Repair damage (may require assistance of a qualified engineer). Minimize use of systems until repairs are completed. SEEPAGE WATER EXITING FROM A POINT ADJACENT TO THE OUTLET PROBABLE CAUSES: 1. An opening in the outlet pipe. 1. Photograph condition. 2. A path for flow has developed along the outside of the outlet pipe. 2. Determine if leakage water is carrying soil particles. POSSIBLE HARMFUL EFFECTS: 1. Continued flows can lead to rapid erosion of embankment materials and failure of the dam. 3. Measure quantity of flow. 4. Close outlet valve and determine whether or not flow decreases or stops. 5. Contact the Division of Dam Safety immediately for further consultation and possible action. DISCHARGES FROM OUTLET ERODING TOE OF DAM PROBABLE CAUSES: 1. Outlet pipe does not extend far enough downstream of embankment toe. 2. Insufficient slope protection and/or means of dissipating the energy of flow at the point of release. 1. Photograph condition. 2. Extend pipe beyond toe (use a pipe of same size and material, and form watertight connection to existing conduit.) 3. Repair damaged area by replacing eroded material with compacted fill. POSSIBLE HARMFUL EFFECTS: FIGURE 27 DETERIORATION AT OUTLET DISCHARGE STRUCTURE 4. Protect area with suitable bedding. 1. Unabated erosion can lead to embankment instability and result in failure of the dam. PROBABLE CAUSES: 1. Photograph condition. 1. Weathering. 2. Repair damage. 2. Undermining of foundation. 3. Excessive pressures exerted on the sidewalls of the structure. POSSIBLE HARMFUL EFFECTS: 1. Can lead to failure of the outlet discharge structure that serves to protect the downstream embankment toe against harmful erosion. FIGURE 28 - 26 - riprap over d. MISCELLANEOUS RESERVOIR CONDITION OBSERVED UNSTABLE RESERVOIR SLOPES PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECTS RECOMMENDED ACTION PROBABLE CAUSES: 1. Area of ancient slide activity. 1. Photograph condition. 2. Removal of support material from base of slope. 2. Contact the Division of Dam Safety immediately for further consultation and possible action. 3. A change in groundwater activity. POSSIBLE HARMFUL EFFECTS: 1. Can lead to massive slides involving large volumes of earth and rock. This has been known to displace enough reservoir water to cause the dam to overtop and fail. MONITORING DEVICES CONDITION OBSERVED INOPERABLE OR DAMAGED INSTRUMENTATION PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECTS PROBABLE CAUSES: 1. Improper installation. 2. Movements monitored. in 3. Carelessness maintenance. the 1. Repair area during being routine 4. Neglect. 5. Vandalism. 6. Excessive wear. FIGURE 29 POSSIBLE HARMFUL EFFECTS: 1. Loss of important data needed to assess whether or not dam is functioning within safe guidelines. - 27 - RECOMMENDED ACTION existing instruments if possible. 2. Consult with a qualified engineer to determine the need for replacements. METALWORK CONDITION OBSERVED GENERAL DETERIORATION: CORROSION, HOLES, ETC. PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECTS RECOMMENDED ACTION PROBABLE CAUSES: 1. Excessive exposure. weathering and 1. Photograph condition. 2. Inadequate maintenance. 2. Scrape and clean, if necessary, to fully assess extent of deterioration. POSSIBLE HARMFUL EFFECTS: 3. Repair or replace as required. 1. Depends on the importance and function of the item in question. Should be assessed on an item-byitem basis. STRUCTURAL DEFICIENCIES: PROBABLE CAUSES: CRACKS, LOOSE OR BROKEN JOINTS 1. Inadequate design and/or OR CONNECTIONS (INCLUDING construction. METAL TO CONCRETE), BENT METAL, ETC 2. Excessive stress through operation. 1. Photograph condition. 2. Repair or replace as required. 3. Wear and tear. 4. Vandalism. 5. Inadequate maintenance. POSSIBLE HARMFUL EFFECTS: 1. Depends on the importance and function of the item in question. Should be assessed on an item-byitem basis. CONCRETE AND CONCRETE DAMS CONDITION OBSERVED PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECTS RECOMMENDED ACTION CRACKING PROBABLE CAUSES: Longitudinal or Horizontal 1. Weathering and exposure. 1. Photograph condition. 2. Excessive stress 2. Have condition evaluated by a qualified engineer 3. Inadequate concrete mix design. 3. Record the location and dimensions of the cracking for comparison to future observations. FIGURE 30 - 28 - Transverse or Vertical POSSIBLE HARMFUL EFFECTS: 1. Depends on the location, extent, cause, length, width and depth of cracking. Should be assessed on an item-by-item basis. FIGURE 31 Diagonal Random Pattern FIGURE 32 FIGURE 33 FIGURE 34 CONDITION OBSERVED PROBABLE CAUSES AND POSSIBLE HARMFUL EFFECTS RECOMMENDED ACTION DETERIORATION PROBABLE CAUSES: Disintegration 1. Weathering and exposure. 1. Photograph condition. 2. Excessive stress. 2. Have condition evaluated by a qualified engineer. 3. Inadequate concrete mix design. 3. Record the location and extent of deterioration for comparison to future observations. 4. Poor workmanship. Distortion POSSIBLE HARMFUL EFFECTS: 1. Depends on the location and extent of deteriorated area. Should be assessed on an item-by-item basis. - 29 - Scaling Popout Spalling Exposed Reinforcing Peeling Efflorescence LEAKAGE THROUGH JOINTS PROBABLE CAUSES: OR CRACKS 1. Deterioration of construction joint has provided flow path. 1. Photograph condition. 2. Have condition evaluated by a qualified engineer. 2. Excessive structural stress has allowed cracks to propagate completely through structure resulting in the development of a flow path. FIGURE 35 POSSIBLE HARMFUL EFFECTS: 1. May be indicative of internal erosion which could lead to an unstable condition. Depends on location of condition and volume of flow. 2. Continually wet conditions promote further deterioration. MONOLITH MISALIGNMENT PROBABLE CAUSES: 1. Excessive stress resulting from high pool levels. 2. Foundation movement. POSSIBLE HARMFUL EFFECTS: 1. Indicative of structural instability and could lead to dam failure. FIGURE 36 - 30 - 1. Photograph condition. 2. Have condition evaluated by a qualified engineer. 2.3 Records a. Inspection Checklist. A convenient way of compiling inspection observations is by recording them directly onto an inspection checklist. The checklist should be attached to a clipboard and carried by the dam inspector as he traverses the entire structure. Sample checklists are provided in Appendix B for convenience. Additional copies can be obtained by contacting DEP (refer to Appendix A for address). The following guidelines are recommended for properly utilizing the checklists. 1. Fill out all basic data on the first page including name of dam, inspection date, weather conditions, name(s) of inspector(s), pool level, DEP I. D. number, etc. 2. Briefly describe all observations. Attach sketches when appropriate. 3. If an item is not applicable, so indicate. 4. Record the fact if nothing is found to be wrong or damaged. Terms such as "good condition" and "not observed" are often sufficient. A good practice to follow along with filling out the inspection checklist is to draw a "field sketch" of observed conditions. A typical field sketch is contained in Appendix B. The field sketch is intended to supplement the information recorded on the inspection checklists; however, it should be used as a substitute for clear and concise inspection checklists. The DEP requires the dam owner to establish a permanent file to retain inspection records including records of actions taken to correct conditions found in such inspections. Copies of the records shall be provided to the department upon request. Without this file, the value of a regular routine dam inspection is very short term. Only through establishment and maintenance of records can evolutionary nature of a dam be comprehended and appreciated. b. Photographs. Inspection photographs can be vitally important because, over time, they serve to provide a pictorial history of the evolving characteristics of a dam. The dam owner/operator often finds pictures to be great money savers because they can illustrate that some observed conditions (seepage, foundation movement, etc.) have existed for many years and may have reached a state of safe equilibrium. With this knowledge, quick and economical remedial actions can be developed and implemented. Without such photographs, one would likely be forced to seek outside professional assistance to investigate the problem prior to developing a repair scheme. Photographs should be dated on the back and provided with brief descriptions. Another convenient method of compiling photographs is to paste or tape the photographs to a sheet of paper and write or type the descriptions on the paper adjacent to the photograph. A word of caution, however, is needed. Over time the tape or paste may lose its adhesiveness. Thus, it is important to make sure each picture is properly dated and described on the back. Since the mid-1990’s, digital photography and word processing software have made it quite convenient for a dam owner / operator to create a documented pictorial record of inspections that can be stored in memory devices indefinitely. However, keeping printed copies on hand of inspection reports with pictures is convenient for frequent review of past conditions. Digital picture files stored on disk or other devices should be named with the dam, date, and subject in the file name, rather than retaining the default naming by the camera. c. Monitoring Data. As previously indicated, it may become necessary to make measurements of various items during the course of a dam inspection. This may include measurements of seepage rates, spillway discharge rates, settlement, and for some dam owners, readings from instruments such as piezometers. It is important that this data also be compiled in a systematic manner and placed in a permanent file. - 31 - SECTION 3.0 DAM MAINTENANCE - 32 - SECTION 3.0 — DAM MAINTENANCE 3.1 Introduction The value and importance of a regular program of routine maintenance cannot be overemphasized. The Division of Dam Safety requires the dam owner to maintain the facility and all appurtenant structures in a safe condition so that the facility may not endanger life; health, safety, or property located above or below the facility. Routine maintenance is defined as minor maintenance, the performance of which neither affects the normal operation of the facility or results in a modification of the original design and/or specifications. The Division of Dam Safety requires the issuance of a written permit for any repairs or maintenance involving modification of a dam from its original design and/or specifications and any repairs or reconstruction involving a substantial portion of the structure. An effective maintenance program has two main elements: 1) a listing of regular maintenance items or tasks; and 2) a maintenance schedule. 3.2 Areas of Required Maintenance In general, the listing of maintenance items or tasks can be broken into four major areas as follows: embankment maintenance spillway maintenance outlet conduit maintenance miscellaneous maintenance The specific tasks that may be required in any of the above areas are discussed in detail later in this section. Maintenance is recognized as a continual day-to-day effort. Through establishment of a formal schedule, many deficiencies which result from prolonged neglect can be averted. A maintenance schedule details specific times when maintenance tasks will performed. a. Embankment. An effective program of regular routine embankment maintenance should include, but not be limited to, the following items or tasks: vegetation control rodent control minor earthwork and erosion repair erosion protection b. Spillway. An effective program of regular routine spillway maintenance should include, but not be limited to, the following items or tasks: vegetation control minor earthwork and erosion repair erosion protection concrete repair - 33 - c. Outlet Conduit. An effective program of regular routine outlet conduit maintenance should include, but not be limited to, the following items or tasks: conduit internal maintenance trash rack maintenance mechanical-electrical-hydraulic maintenance concrete repair d. Miscellaneous. An effective program of miscellaneous maintenance includes all remaining areas, items, or devices not covered under the categories of embankment, spillway, or outlet conduit maintenance. As an example, this should include, but not be limited to, the following items or tasks: 3.3. operable equipment maintenance (mechanical, electrical, hydraulic) monitoring instruments security devices access roads Maintenance Items a. Vegetation Control. The first maintenance requirement is to keep all portions of the dam clear of unwanted vegetative growth. Excessive growth is harmful in the following ways: It can obscure the view of the embankment and prevent a thorough inspection. Weeds can discourage the growth of desirable grasses. Some root systems can decay and rot, providing a tunnel for water to pass through and lead to a piping failure. Large trees could be uprooted during a storm and the resulting large hole left by the root system could lead to breaching of the dam. Root systems can cause the uplift of concrete slabs or structures. In general, an effort should be made at least twice a year to cut down overgrowth and to keep vegetation under control. Like trimming one's lawn, the more frequently the dam owner/operator attends to the vegetation control needs of the dam, the easier it is. Thus, there may be an advantage to tending to this need often so that the chore never becomes too large to tackle without additional assistance and equipment. b. Rodent Control. Rodents such as groundhogs, muskrats, and beavers are naturally attracted to areas of ponded water such as dams and reservoirs. Earth dams are most susceptible to problems caused by these rodents. As a matter of fact, beavers can cause problems for any type of dam construction. Table 3.0 presents a description of each rodent, potential problems caused by each, recommended methods of control, and measures to repair the damage. - 34 - Under Pennsylvania law the control or extermination of groundhogs, muskrats and beavers is subject to certain restrictions. Prior to taking any action against these rodents the dam owner/operator is advised to contact the Wildlife Conservation Officer through a regional office of the Pennsylvania Game Commission. Information is available on the Game Commission’s website at www.pgc.state.pa.us. Table 3.0 RODENTS AND RODENT CONTROLS Rodent Methods of Control Groundhog or Woodchuck Problem Remedial Measures Fumigation or Shooting Groundhogs usually burrow into the downstream embankment slope forming tunnels and dens inside the dam above the phreatic surface. These passageways not only decrease the stability of the dam, but could become conduits during flooding periods leading to breaching of the dam. Fill burrow with slurry mixture of earth (90 percent) and cement (10 percent) by pouring through large diameter pipe. Outer surface should then be covered with well-compacted earth and vegetation reestablished. Muskrat Trapping Muskrats usually burrow into the upstream embankment slope. Their burrows begin six to 18 inches below the water surface and penetrate the embankment on an upward slant. At distances up to 15 feet from the entrance, a dry chamber may be hollowed out above the water level. Once a muskrat den is occupied, a rise in the water level will cause the muskrat to dig farther and higher to excavate a new dry chamber. Damage (and the potential for problems) is compounded where groundhogs or other burrowing animals construct their dens in the embankment opposite muskrat dens. Same as for groundhog burrows. Beaver Trapping Beavers often build dens along the upstream embankment slope and into the dam. They also have been known to block spillways with their own dams. Fill burrows as recommended above. Constant vigilance and removal of cuttings placed in spillways is also necessary. - 35 - c. Earthwork. As outlined in Section 2.0, there are many different causes of deterioration of the earth surfaces of a dam. For example, wave action may cause erosion (scarps) along the upstream slope, vehicles may cause ruts in the crest, or runoff waters may leave erosion gullies on the upstream and downstream slopes and in earthen spillways. Damage of this nature must be repaired on a continual basis. Minor soil erosion is easily repaired. The first consideration is to use new soil material similar in makeup to the soil lost. The new soil should not contain vegetation, organic matter, trash or large rock fragments. In addition, the new soil should be neither too wet nor too dry, but should contain enough moisture to enable good compaction. Prior to placing new soil, the repair area must be prepared by removing all loose and/or unsuitable material such as loose soil, brush, roots, trash, or large rocks. Finally, the new soil should be placed in thin layers, six inches or less, and hand tamped until firm. In order to prevent future erosion, consideration should be given to protecting the repaired area with erosion resistant rock or other material (i.e. concrete or asphalt) if appropriate. d. Concrete. Even though concrete is an extremely durable material, periodic maintenance is required to repair deteriorated areas. Deteriorated areas are usually in the form of weathering or cracking as discussed in Section 2.0. In general, it is a good practice to repair concrete deterioration in the early stages when it is most manageable. However, concrete deterioration can be either active or relatively stable. Active deterioration is caused by factors and elements that are on-going and have yet to stabilize. These factors are likely to result in additional deterioration and even damage to any repairs. Relatively stable deterioration is caused by factors and elements that are not expected to occur again. Concrete deterioration can be generated by so many varying conditions, it is often impossible to list them all, but often the reason is apparent to an experienced engineer. Such consultation should be sought prior to attempting any concrete repairs. For additional information regarding general concrete repair, see References 3, 5, 6 and 35 identified in Appendix C. e. Conduits. The conduits (or pipes) through a dam are some of its most important features and must be adequately maintained. The outlet conduit not only includes the pipe transporting the water but also the trash rack at the inlet to prevent debris from entering and clogging the pipe. 1. Internal Maintenance. Problems detected during inspection of the conduits should be immediately addressed and subsequently checked to make sure that the repair was effective. Due to the importance of the conduit and the difficulty of properly repairing it, professional supervision should be obtained. 2. Trash Racks. Maintenance should include periodically checking the rack for rusted and broken sections and repairing as needed. The trash rack should be checked frequently during and after storm events to ensure it is functioning properly and to remove accumulated debris. f. Mechanical. It is essential that stored water be released when required. An operable outlet provides the only means for emergency drawdown of the reservoir and is essential to the dam's safety. Table 3.1 lists the required mechanical maintenance procedures, their purpose, recommended time intervals, and comments. - 36 - g. Electrical. In general, electricity is used on dams for the following: provide lighting operate outlet gates operate recording equipment operate spillway gates operate other electrical equipment like elevators or cranes Thus, it is important that the electrical system be well maintained. Maintenance should include a thorough check of the fuses and a test of the system to be sure everything is properly functioning. Moisture and dust should be kept away from the electrical system, and wiring should be checked for corrosion and mineral deposits. Any necessary repairs should be completed immediately, and records of the repair work should be kept. In addition, generators kept for back-up emergency power must be maintained. Maintenance should include oil changes, battery checks, antifreeze checks and making sure that fuel is readily available. h. Hydraulic. A hydraulic control system is often used to open and close the valves or sliding gates of the outlet or intake works. The hydraulic system usually has long hoses and pipelines to transmit hydraulic fluid to the gate-operating cylinders, and there are gauges to indicate hydraulic pressure in the system. Routine checks should be performed on the hydraulic cylinders, hoses and pipelines as required. Table 3.1 MECHANICAL MAINTENANCE PROCEDURES Maintenance Procedure Recommended Time Interval Purpose 1. Cycle outlet gates through full operating range* Prevents buildup of rust on contact surfaces of the operating mechanism and possible seizure of mechanism due to operating parts rusting together Semi-annually (unless otherwise directed by gate manufacturer) 2. Lubrication To reduce wear and protect mechanism against adverse effects of weather Per manufacturer’s instructions or as needed. 3. Painting or greasing of ferrous metal Prevent erosion Annually or as needed - 37 - Comments Notes should be made of operating characteristics. Rough, noisy, or erratic movement of the gate should be noted and investigated immediately. When repainting areas, do not allow paint to get on gate seats, gate wedges, Maintenance Procedure Recommended Time Interval Purpose Comments gate stems in the reach where the stems pass through the stem guides, or other friction surfaces where paint could cause binding. Heavy grease should be applied on surfaces where binding can occur. 4. Aligning and tightening of stem guides or brackets 5. Readjustment of wedge system Decrease leakage As needed as noted by inspection Adjustment should never be attempted by inexperienced personnel. Always employ experienced personnel recommended by gate supplier or manufacturer. *It is recommended that cycling be done during periods of low reservoir storage to prevent large outlet discharges. i. Miscellaneous. 1. Access Roads. For a dam to be operated and maintained there must be a safe means of access to it at all times. The road surface must be maintained to allow safe passage of automobiles and any required equipment for servicing the dam, in any weather conditions. Routine observations of any cut and fill slopes along the sides of the road should be made. If unstable conditions develop, professional help should be obtained and remedial measures initiated. 2. Monitoring Devices. Monitoring devices, as presented in Section 1.4, for the most part do not require routine maintenance. The main exceptions are the piezometers, weirs and stakes (in staked areas). The weirs should be regularly checked and cleared of any debris. They should also be checked for loose boards or loose metal stripping, and repaired as necessary. Staked areas are particularly susceptible to vandalism. Stakes should be checked routinely and replaced immediately where needed. Piezometers are to be maintained in an operable state at all times. Consult the recommendations of the manufacturer for guidelines on maintenance. - 38 - 3. Winterizing. Ice can exert excessive force and damage various components of a dam. In addition, ice formation in and around spillways, and in conduit outlets, can cause blockages and prevent their proper functioning. Ice formation can be prevented by heaters, aeration equipment, or forced movement of water. The owner/operator should be aware of these potential problems and take appropriate action during severe cold spells. 4. Vandalism Prevention. Vandalism is a common problem whose best solution is prevention. Initial costs of installation of fences to prevent access to the area of the dam by unauthorized persons, and providing heavy duty doors and locks on buildings housing equipment, are realized many times over. As many measures as possible should be undertaken to prevent vandalism and protect all equipment and surfaces from the public. Also, owners should be aware of their responsibility for public safety, including the safety of people not authorized to use the facility. "No Trespassing" signs should be posted, and fences and warning signs should be erected around dangerous areas. It is recommended that the dam owner regularly consult with an insurance professional to assess the adequacy of existing liability insurance. 3.4 Maintenance Schedule Every dam owner should develop a schedule of regular routine maintenance and incorporate it as part of the overall operation plan for the facility. In general, it is recommended that the entire program of maintenance be performed at least twice per year. Preferably, maintenance should be performed once in the spring, soon after winter snowmelt, and once in the late fall, sometime before the first snowfall. In addition, each dam owner should assess whether his facility has areas or items which require maintenance on a more frequent basis (i.e., daily, weekly, or monthly). 3.5 Maintenance Records As in the case of inspection records, thorough maintenance records are of utmost importance. A record should be kept of all maintenance activities. Information to be recorded should include the following as a minimum: Date and time of maintenance. Testing and exercising of outlet and spillway gates and valves, controls, and standby equipment Maintenance activities such as lubrication, cleaning, clearing debris from channels, tree removal, repairing erosion, etc. The data should be recorded by the person responsible for maintenance. - 39 - - 40 - SECTION 4.0 DAM OPERATION - 41 - SECTION 4.0 - DAM OPERATION 4.1 General a. Introduction. The purpose of developing and implementing operating procedures or an operation plan is to provide for maximum dam safety by formalizing a regular schedule of routine tasks. An effective operations plan provides the information and instruction needed to allow an inexperienced person to perform all the tasks required to operate and maintain a dam safely. Assembling the required information and writing a custom-made operation plan is the responsibility of the dam owner/operator. This section is intended to serve as a guide to assist the dam owner/operator in preparing such a plan. Additional assistance from an experienced consulting engineer may also be helpful. b. Elements of an Operation Plan. The extent of an operation plan is dependent on the complexity of the dam itself. Contributing factors include dam size, number of appurtenances, and, in particular, the number of operable mechanisms. Nevertheless, the most effective plans are usually the simplest. The principal elements of an effective operation plan are briefly presented below. Section I: Background Data — A typical dam owner/operator possess a good deal of information about his facility. Very often the information is scattered about or reviewed so rarely as to make it of little use. This section of the operation plan serves to organize available background data to make it more accessible. Section I Schedule of Routine Tasks — A schedule that includes both day-to-day tasks and tasks performed less frequently through a given year. The schedule serves to formalize inspection and maintenance procedures such that an inexperienced person could determine when a task is to be performed by merely consulting the schedule. Section Ill: Emergency Procedures — This is perhaps the most important section. It contains a formal plan for reacting to dam emergencies. It involves coordination between the dam owner/operator, local agencies and downstream residents. 4.2 Operation Plan a. Section I — Background Data. Prior to assembling the items suggested below, the dam owner/operator will need to gather all the information in his possession regarding the dam. Examples may include design reports, photographs, plans, maps and miscellaneous correspondence pertaining to the facility. 1. Vital Dam Statistics. Compile a list of dam statistics including the following (For definitions of terms refer to Appendix D of this manual). a) Embankment - b) Type of Dam Height of Dam Length of Crest Width of Crest Angle of Upstream Slope Angle of Downstream Slope Available Freeboard Spillway - Type of Spillway - Length of Spillway Crest - Spillway Crest Elevation - Normal Pool Elevation - 42 - - Top of Dam Elevation DEP I. D. Number County Location Township Location Stream Name Year Completed Hazard Classification - Available Freeboard Greatest depth of flow ever observed over spillway crest including date of occurrence c) Outlet Statistics - Size and Type of Outlet - Size and Type of Outlet Control Device - Inlet Invert Elevation - Outlet Invert Elevation 2. Description of Appurtenances. As briefly as possible, describe the various appurtenances of the facility, including location and function. Include sketches and photographs as often as possible. Any operable or self-regulating appurtenance should be included. Typically the list will contain the following: - Spillway Spillway Gates Outlet Conduit Control device Monitoring Devices 3. Operating Instructions for Operable Mechanisms. Develop a clear, step-by-step set of instructions for operating all operable mechanisms associated with the dam. This will typically include the outlet conduit control valve or possibly the spillway gates if applicable. The instructions should be complete regardless of the relative degree of simplicity or complexity involved. Emphasize proper sequence and include sketches, drawings and photographs to aid in identifying specific handles, cranks, buttons, etc. 4. Monitoring Instructions and Forms. Instructions on how to utilize monitoring instruments and how to take measurements at monitoring points must be provided. A map identifying each instrument and monitoring point should be included. Forms for recording the data will also be needed. The assistance of a qualified engineer may be useful in developing this section. 5. Maintenance Instructions. Any special instructions for performing periodic maintenance should be given in detail. This will allow new personnel to understand the task and experienced personnel to make sure that they have completed the work properly (consult Section 3). 6. Information Bibliography. Catalog all available background data in a single listing. Include titles, authors or agencies responsible for publication, date or origin, brief description and permanent location of material (e.g., filing cabinet in basement). Even materials without titles or authors such as photographs and maintenance information should be listed. 7. Telephone List A comprehensive up-to-date listing of important telephone numbers should include the following (see Appendix A). • - Owner/operator (home and office) Employees actively involved with dam. Local emergency management (civil defense) agencies (county and municipal). State Police Local police and fire departments. Qualified local engineering consultants. DEP's Division of Dam Safety Downstream residents (if practical). b. Section II – Schedule of Routine Tasks. The four categories of routine tasks are as follows: operating tasks, maintenance tasks, inspection tasks and monitoring tasks. The frequency of required performance of a given task is dependent upon factors peculiar to the dam itself such as hazard classification (see Reference 22 Appendix C). Suggested minimum frequencies for various activities are: 1. Category 1 ―High Hazard‖ Dams. Failure of the dam would cause excessive economic loss and would result in substantial loss of human life. Daily – Surveillance by the dam owner/operator or caretaker. Weekly – Monitoring of seepage. - 43 - Monthly – Gathering, immediately plotting and interpreting observation well and piezometer data. Quarterly – Visual inspection by dam owner/operator. Bi-Annually – Test operation of outlet and spillway mechanical components. Annually – Inspection by a qualified registered professional engineer. Reading horizontal and vertical control monuments (more frequently if necessary). Routine maintenance as required. Additional Inspections – Immediately following excessive flooding and/or earthquake shaking. 2. Category 2 ‖High Hazard‖ Dams. Failure of the dam would cause appreciable economic loss and could result in the loss of a few human lives. Weekly – Surveillance by the dam owner/operator or caretaker. Monthly – Gathering, plotting and interpreting observation well and piezometer data. Quarterly – Visual inspection by dam owner/operator. Annually – Inspection by a qualified registered professing engineer. Test operation of outlet and spillway mechanical components. Reading horizontal and vertical control monuments (more frequently if necessary). Routine maintenance as required Additional Inspections – Immediately following excessive flooding and/or earthquake shaking. 3. All ―Non-High Hazard‖ Category 3 and Category 4 Dams. Failure would cause minimal economic damage and no loss of life would be expected. Monthly – Surveillance by the dam owner/operator or caretaker. Monitoring of seepage. Gathering, plotting and interpreting observation well and piezometer data. Annually – Visual inspection by dam owner/operator. Testing of the outlet. Every Five Years – Reading of horizontal and vertical control monuments. Route maintenance as required. Additional Inspections – Immediately following excessive flooding and/or earthquake shaking. c. Section Ill – Emergency Action Plan. Pennsylvania law requires the dam owner/operator of any dam or reservoir that may cause loss of life or substantial property damage as a result of failure to develop an Emergency Action Plan. An Emergency Action Plan (EAP) is a formal document that identifies potential emergency conditions at a dam and specifies preplanned actions to be followed in response to a dam hazard emergency, which are designed to minimize property damage and prevent loss of life. The EAP describes procedures and information to assist the dam owner in surveillance of developing conditions and issuing timely notification of an emergency situation to responsible emergency management authorities. It also contains inundation maps that show the emergency management authorities the critical areas for action in the event of a dam hazard emergency. An EAP must be tailored to a dam’s specific conditions, to the capabilities of the owner and operator, and to the emergency response organizations that will implement the EAP. Your county’s emergency management office, the Pennsylvania Emergency Management Agency (PEMA), and DEP’s Division of Dam Safety all have a hand in review and approval of a dam emergency action plan. If your dam requires an Emergency Action Plan and you do not have one approved, or if your EAP was approved more than four years ago, you should develop or revise your EAP according to the DEP / PEMA publication: GUIDELINES FOR DEVELOPING AN EMERGENCY ACTION PLAN (EAP) FOR HAZARD POTENTIAL CATEGORY 1 and 2 DAMS. (DEP Publication No. 3140-BK-DEP1956). The EAP guidelines booklet is available from DEP’s Division of Dam Safety, along with a data CD including a sample plan template and other publications. The guidelines and other documents can be viewed and downloaded via DEP’s public eLibrary. (From the DEP website at: www.dep.state.pa.us select Forms & - 44 - Publications under the Quick Access menu at the left of the home page. Then look under Publications, then Waterways Engineering, then Dam Safety for all available publications). The Emergency Action Plan must be followed in the event of a dam hazard emergency. A dam hazard emergency refers to any condition that the dam owner/operator or the DEP finds to be an imminent threat to life or property above or below a dam — whether arising from the condition of the dam or extraordinary natural conditions — including, but not limited to, flood, earthquake, fire and ice jam. In general, an effective EAP establishes and/or identifies the following: The areas that will be flooded and to what severity. Whom to notify for evacuation in case of an emergency, and when. Where evacuees will be housed or sheltered in the event of extensive damage to residential structures. The routes and roadways to be used as evacuation routes. Where roadblocks will be needed along potentially flooded routes. The agencies and/or persons who will be required to perform which tasks. A primary and backup communication system that considers the possibility of a power blackout. A predetermined time should be established when evacuation efforts are to be terminated. Previous studies may be available to indicate what flood level is no longer safe to continue evacuation in each area. Upstream flood levels, crest travel time, and time needed to evacuate all people and equipment should be the determining factors in terminating evacuation assistance. The farther downstream a damage center is located, the more chance there is for a long flood warning and more time to carry out an organized evacuation. Protection of life should also be considered before anything else in an evacuation effort. The Act of May 16, 1985 (Act 1985-15), amended Section 13 of the Dam Safety and Encroachments Act (35 P.S. 093.13) to add the following new subsection (b): "(b) In addition to the duties of subsection (a), the owner of any high hazard dam which has been classified as such by the DEP shall post notices in public places in any area which might be affected by the failure of the dam' The Act defines "high hazard dam” as "any dam so located as to endanger populated areas downstream by its failure.” This definition includes any dams categorized as Hazard Classifications 1 and 2 under the Department's Chapter 105. Upon review, some Category 2 dams may be exempted from this requirement. The permittee or owner of a hazard potential Category 1 or Category 2 dam must post notices in public locations in areas that may be affected by the failure of the dam. Also, the notice must be posted by the permittee or owner in public places within each political subdivision situated within the inundation area downstream of the dam. The notice must be posted in the city, borough and township buildings in the affected municipalities, with the management’s permission. Additionally, the notice shall be posted in locations within the inundation area, such as, post offices, libraries, grocery stores or gas stations, with the management’s permission. The Notice shall state that a copy of the Emergency Action Plan for the dam is available for inspection at the following locations: (1) County Emergency Management Offices (list locations) (2) Municipal Emergency Management Offices (list locations) (3) Offices or Residence of the Dam Owner (list location) - 45 - NOTICE DAM HAS BEEN CLASSIFIED BY THE DEPARTMENT OF ENVIRONMENTAL PROTECTION, DIVISION OF DAM SAFETY, AS A HIGH HAZARD DAM; THIS IS A DAM SO LOCATED AS TO ENDANGER POPULATED AREAS DOWNSTREAM BY ITS FAILURE. AN EMERGENCY ACTION PLAN HAS BEEN DEVELOPED FOR (NAME OF DAM) A COPY OF THIS PLAN, INCLUDING AN INUNDATION MAP NOTING AREAS IN (NAME OF MUNICIPALITY AND/OR MUNICIPALITIES)) SUBJECT TO FLOODING IN THE EVENT OF FAILURE, IS AVAILABLE FOR PUBLIC INSPECTION AT THE FOLLOWING LOCATIONS: (DAM OWNER & ADDRESS) (LOCAL EMA OFFICE & ADDRESS) (COUNTY EMA OFFICE & ADDRESS) (LOCAL EMA OFFICE & ADDRESS) This NOTICE is posted per Department of Environmental Protection’s Chapter 105 Dam Safety and Waterway Management §105.134(c). - 46 - APPENDIX A IMPORTANT TELEPHONE NUMBERS AND ADDRESSES - 47 - For more information about dams in Pennsylvania and DEP’s Dam Safety Program, contact: Department of Environmental Protection Bureau of Waterways Engineering and Wetlands Division of Dam Safety P.O. Box 8554 Harrisburg, PA 17105-8554 717-787-8568 DEP’s Watershed Management Program Regional Offices Northwest Region 230 Chestnut St. Meadville, PA 16335-3481 814-332-6984 Northcentral Region 208 W. Third St., Suite 101 Williamsport, PA 17701 570-327-3574 Northeast Region 2 Public Square Wilkes-Barre, PA 18711-0790 570-830-3093 Counties: Butler, Clarion, Crawford, Elk, Erie, Forest, Jefferson, Lawrence, McKean, Mercer, Venango and Warren Counties: Bradford, Cameron, Clearfield, Centre, Clinton, Columbia, Lycoming, Montour, Northumberland, Potter, Snyder, Sullivan, Tioga and Union Counties: Carbon, Lackawanna, Lehigh, Luzerne, Monroe, Northampton, Pike, Schuylkill, Susquehanna, Wayne and Wyoming Southwest Region 400 Waterfront Drive Pittsburgh, PA 15222-4745 412-442-4000 Southcentral Region 909 Elmerton Ave. Harrisburg, PA 17110 717-705-4707 Southeast Region 2 East Main St. Norristown, PA 19401 484-250-5970 Counties: Allegheny, Armstrong, Beaver, Cambria, Fayette, Greene, Indiana, Somerset, Washington and Westmoreland Counties: Adams, Bedford, Berks, Blair, Cumberland, Dauphin, Franklin, Fulton, Huntingdon, Juniata, Lancaster, Lebanon, Mifflin, Perry and York Counties: Bucks, Chester, Delaware, Montgomery and Philadelphia For more information, visit www.dep.state.pa.us, keyword: Dam Safety. - 48 - PENNSYLVANIA EMERGENCY MANAGEMENT AREA OFFICES Western Area Office Pennsylvania Emergency Management Agency 276 Stormer Road Indiana, PA 15701-8933 Emergency Tel: 717-651-2001 Non-Emergency Tel: 724-357-2990 Central Area Office Pennsylvania Emergency Management Agency 2605 Interstate Drive Harrisburg, PA 17110-9364 Emergency Tel: 717-651-2001 Non-Emergency Tel: 717-651-7060 Eastern Area Office Pennsylvania Emergency Management Agency Hamburg Center Hamburg, PA 19526 Emergency Tel: 717-651-2001 Non-Emergency Tel: 610-562-3003 PEMA - State Emergency Operations Center 2605 Interstate Drive Harrisburg, PA 17110-9364 Tel: 717-651-2001 800-424-7362 - 49 - APPENDIX B INSPECTION CHECKLISTS This and other forms and publications can be viewed, printed and saved to your own computer from the Dam Safety homepage at www.depweb.state.pa.us/waterwayseng, then click on Dam Safety. - 50 - - 51 - DAM INSPECTION CHECKLIST Pennsylvania Department of Environmental Protection Bureau of Waterways Engineering Division of Dam Safety NAME OF DAM: LOCATION: DEP DAM NO.: D Municipality: - County: DEP CLASSIFICATION DATA: Size: Hazard: PHYSICAL DATA: Type of Dam: Height of Dam: ELEVATIONS: Normal Pool: Pool at Inspection: Normal Pool Storage Capacity: DAM OWNER: Tailwater at Inspection: OPERATOR: ADDRESS: PHONE: ( )FAX NO.: ( )E-MAIL ADDRESS: A completed and signed Dam Owners Notice Checklist is to accompany this Inspection Checklist. PERSONS PRESENT AT INSPECTION: Name Title/Position Representing DATE OF INSPECTION: / / WEATHER: TEMPERATURE: This is to certify that the above dam has been inspected and the following are the results of this inspection. Signature of Registered Professional Engineer (P.E. Seal Required) Date Revised: 1/2009 - 52 - Date COMMENTS REPAIR DATE: IVESTIGATE CONDITION DEP DAM NO.: MONITOR ITEM NAME OF DAM: EMBANKMENT: CREST 1 2 3 4 5 6 7 8 9 Surface Cracking Sinkhole, Animal Burrow Low Area(s) Horizontal Alignment Ruts and/or Puddles Vegetation Condition Warning Signs Additional Comments (Refer to item number if applicable): EMBANKMENT: UPSTREAM FACE 10 11 12 13 14 15 16 17 Slide, Slough, Scarp Slope Protection Sinkhole, Animal Burrow Emb.-Abut. Contact Erosion Vegetation Condition Additional Comments (Refer to item number if applicable): Dam Safety High Hazard Dam Inspection Checklist Page 2 of 10 Date Revised: 1/09- COMMENTS REPAIR CONDITION DATE: IVESTIGATE DEP DAM NO.: MONITOR ITEM NAME OF DAM: EMBANKMENT: DOWNSTREAM FACE 18 19 20 21 22 23 24 25 26 27 Wet Area(s) (No Flow) Seepage Slide, Slough, Scarp Emb. - Abut. Contact Sinkhole, Animal Burrow Erosion Unusual Movement Vegetation Control Additional Comments (Refer to item number if applicable): EMBANKMENT: INSTRUMENTATION 28 29 30 31 32 33 34 35 36 37 Piezometers/Observ. Wells Staff Gauge and Recorder Weirs Survey Monuments Drains Low Flow Release Frequency of Readings Location of Records Additional Comments (Refer to item number if applicable): Dam Safety High Hazard Dam Inspection Checklist Page 3 of 10 Date Revised: 1/09- COMMENTS REPAIR DATE: IVESTIGATE CONDITION DEP DAM NO.: MONITOR ITEM NAME OF DAM: DOWNSTREAM AREA 38 39 40 41 42 43 44 45 46 47 Abutment Leakage Foundation Seepage Slide, Slough, Scarp Drainage System Boils Wet Areas Reservoir Slopes Access Roads Security Devices Act 91 Run-of-the-River Signs or Bouys 48 49 Additional Comments (Refer to item number if applicable): SPILLWAYS: ERODABLE CHANNEL 50 51 52 53 54 55 Slide, Slough, Scarp Erosion Vegetation Condition Debris Additional Comments (Refer to item number if applicable): Dam Safety High Hazard Dam Inspection Checklist Page 4 of 10 Date Revised: 1/09- COMMENTS REPAIR DATE: IVESTIGATE CONDITION DEP DAM NO.: MONITOR ITEM NAME OF DAM: SPILLWAYS: NON-ERODABLE CHANNEL 56 57 58 59 60 61 62 63 64 Sidewalls Channel Floor Unusual Movement Approach Area Weir or Control Discharge Channel Boils Additional Comments (Refer to item number if applicable): SPILLWAYS: DROP INLET 65 66 67 68 69 Intake Structure Trashrack Stilling Basin Additional Comments (Refer to item number if applicable): Dam Safety High Hazard Dam Inspection Checklist Page 5 of 10 Date Revised: 1/09- COMMENTS REPAIR CONDITION DATE: IVESTIGATE DEP DAM NO.: MONITOR ITEM NAME OF DAM: OUTLET WORKS 70 71 72 73 74 75 76 77 78 79 80 81 82 Intake Structure Trashrack Stilling Basin Primary Closure Secondary Closure Control Mechanism Outlet Pipe Outlet Tower Outlet Structure Seepage Unusual Movement Additional Comments (Refer to item number if applicable): CONCRETE/MASONRY DAMS: UPSTREAM FACE 83 84 85 86 87 88 Surface Conditions Condition of Joints Unusual Movement Abutment-Dam Contacts Additional Comments (Refer to item number if applicable): Dam Safety High Hazard Dam Inspection Checklist Page 6 of 10 Date Revised: 1/09- COMMENTS REPAIR CONDITION DATE: IVESTIGATE DEP DAM NO.: MONITOR ITEM NAME OF DAM: CONCRETE/MASONRY DAMS: DOWNSTREAM FACE 89 90 91 92 93 94 95 96 Surface Conditions Condition of Joints Unusual Movement Abutment-Dam Contacts Drains Leakage Additional Comments (Refer to item number if applicable): CONCRETE/MASONRY DAMS: CREST 97 98 99 100 101 102 103 Surface Conditions Horizontal Alignment Vertical Alignment Condition of Joints Unusual Movements Additional Comments (Refer to item number if applicable): Dam Safety High Hazard Dam Inspection Checklist Page 7 of 10 Date Revised: 1/09- COMMENTS REPAIR DATE: IVESTIGATE CONDITION DEP DAM NO.: MONITOR ITEM NAME OF DAM: RESERVOIR AREA 104 105 106 107 108 109 110 111 Sedimentation Slope Stability Sinkholes Fractures Unwanted Growth Storage Gage Additional Comments (Refer to item number if applicable): Final Comments: Dam Safety High Hazard Dam Inspection Checklist Page 8 of 10 Date Revised: 1/09- DAM OWNERS NOTICE CHECKLIST Pennsylvania Department of Environmental Protection Bureau of Waterways Engineering Division of Dam Safety NAME OF DAM: DEP DAM NO.: This is to certify that both the Downstream Hazard Description is accurate and the Posted Notice locations listed below have been inspected and the following are the results of these inspections. Name of Dam Owner Signature of Dam Owner Date This Dam Owners Notice Checklist is to accompany the Inspection Checklist filed by the Engineer. EMERGENCY ACTION PLAN Date of Last Update of Emergency Plan: Downstream Hazard Description (Refer to sections II.C and II.D in the EAP), additionally, specify any new developments, structures, etc. downstream within the inundation area: COMMENTS REPLACED LOCATION MISSIING DATE INSPECTED (Refer to section V.A in the EAP) EXISTING ITEM POSTED NOTICES 1 2 3 4 5 6 7 8 9 10 11 12 Additional Comments (Refer to item number if applicable): Dam Safety High Hazard Dam Inspection Checklist Page 9 of 10 Date Revised: 1/09- Dam Safety High Hazard Dam Inspection Checklist Page 10 of 10 Date Revised: 1/09- APPENDIX C REFERENCE LIST (Original Edition) - 61 - REFERENCES 1. ASCE/USCOLD (1975) Lessons from Dam Incidents, USA, American Society of Civil Engineers, New York. 2. American Concrete Institute (1968) "Guide for Making a Condition Survey of Concrete in Service," Journal of the American Concrete Institute, Proceedings, Vol. 65, No. 11, pp. 905-918. 3. American Concrete Institute (1982) ACE Manual of Concrete Practice 1982, Part 7, Materials and General Properties of Concrete, American Concrete Institute, Detroit, Michigan. 4. Chief of Engineers (1975) Recommended Guidelines for Safety Inspection of Dams, National Program of Inspection of Dams, Vol. I, Appendix ID, Dept. of the Army, Washington, D.C. 5. Concrete Construction Publication, Inc. (1983) Four Steps to Successful Concrete Repair, Volume 28. Number 1, Addison, Illinois, January. 6. Concrete Construction Publication, Inc. (1985) Crack Repair, Volume 30, Number 1, Addision, Illinois, January. 7. Federal Coordinating Council for Science, Engineering and Technology, Ad Hoc Interagency Committee on Dam Safety (1979) Federal Guidelines for Dam Safety, Federal Emergency Management Agency, Government Printing Office, Washington, D.C. 8. Federal Emergency Management Agency (1982) Interagency Committee on Dam Safety (ICODS), Subcommittee on Emergency Action Planning, Dam Safety, Emergency Action Planning. 9. Forest Service And Soil Conservation Service, U.S. Dept of Agriculture (1980) Guide for Safety Evaluation and Periodic Inspection of Existing Dams. 10. Golze, A.R., ed. (1977) Handbook of Dam Engineering, Van Nostrand Reinhold Co., New York. 11. Honaker, Harry Keith, Guidelines for Maintenance and inspection of Dams in Kentucky, Kentucky Division of Water Resources. 12. ICOLD (1969) General Considerations Applicable to Instrumentation for Earth and Rock fill Dams, Committee on Observations of Dams and Models, Bulletin No. 21, November. 13. !COLD (1981) Automated Observation for Instantaneous Safety Control of Dams and Reservoirs, Bulletin No. 41, January. 14. Jansen, R. B. (1968) A Prescription for Dam Safety— Instrumentation and Surveillance, Conference of College of Engineering, University of California, Berkeley. 15. Jansen, R. B. (1980) Dams and Public Safety, U.S. Bureau of Reclamation, Government Printing Office, Washington, D.C. (reprinted in 1983). 16. Mills, George E.'(1983) Operation, Maintenance, and Inspection Manual for Dams, Dikes, and Levees, Ohio Department of Natural Resources. 17. Mine Safety and Health Administration, Mine Waste and Geotechnical Engineering Division (1984) Construction Inspection of Dams and Coal Refuse Embankments, Bruceton Mills, Pennsylvania. 18. National Association of Conservation Districts "Darn Safety — Who is Responsible?", slide show produced by National Association of Conservation Districts, Washington, D.C. 19. National Research Council (1982) Geotechnical Instrumentation for Monitoring Field Performance, National Academy Press, Washington, D.C. 20. National Research Council, Committee on the Safety of Existing Dams (1983) Safety Evaluation of Existing Dams, Evaluation and Improvement, National Academy Press, Washington, D.C. 21. Pennsylvania State Legislature (1978) Pennsylvania Dam Safety Encroachments Act as amended (32 P.S. §§693.1-693.27). - 62 - 22. Pennsylvania Environmental Quality Board (1980) Chapter 105. Dam Safety and Waterway Management, Rules and Regulations. 23. Schurer, John, et. al. (1983) State of Colorado Dam Safety Manual, State Engineer's Office, Colorado. 24. Sharma and Raphael (1979/1981) Genera! Considerations on Reservoir Instrumentation, Committee on Measurements, USCOLD. 25. Sowers, C. F. (1961) "The Use and Misuse of Earth Dams:' Consulting Engineering, July. 26. Spear, Andrew D. (1981) PP&L Owned Dams and Related Facilities Inspection Program, Pennsylvania Power and Light Company, Allentown, Pennsylvania. 27. State of Illinois, Department of Water Resources (1980) Guidelines and Forms for Inspection of Illinois Dams, Springfield, Illinois. 28. Tschantz, Bruce A. (1972) The Inspection and Maintenance of Privately Owned Dams in Tennessee, University of Tennessee. 29. USCOLD (1983) Guidelines for inspection of Dams Following Earthquakes, U.S. Government Printing Office. 30. U.S. Army Corps of Engineers (1971 and 1976) Instrumentation of Earth and Rock fill Dams, Parts 1 and 2, EM 1110-2-1908, August 1971 and November 1976. 31. U.S. Army Corps of Engineers (1980a) Flood Emergency Plans, Guidelines for Corps Dams, Hydrologic Engineering Center, Davis, California, June, 47 pp. 32. U.S. Army Corps of Engineers (1980b) Instrumentation for Measurement of Structural Behavior of Concrete Structures, EM 1110-2-4300, September. 33. U.S. Army Corps of Engineers (1982b)National Program for Inspection of Non-Federal Dams— Final Report to Congress. 34. U.S. Dept. of the Interior, Bureau of Reclamation (1974) Earth Manual, 2d. ed., Government Printing Office, Washington, D.C. 35. U.S. Department of the Interior, Bureau of Reclamation (1975) Concrete Manual, A Water Resources Technical Publication, U.S. Bureau of Reclamation, Government Printing Office, Washington, D.C. 36. U.S. Dept. of the Interior, Bureau of Reclamation (1977) Design of Arch Dams, Denver, Colorado. 37. U.S. Dept. of the Interior, Bureau of Reclamation (1977) Design of Arch Dams, Denver, Colorado. 38. U.S. Dept. of the Interior, Bureau of Reclamation (1977) Design of Small Dams, Denver Colorado. 39. U.S. Dept of the Interior, Bureau of Reclamation, Division of Dam and Structural Safety (1982) Operation and Maintenance Guidelines for Small Dams. 40. U.S. Dept of the Interior, Bureau of Reclamation (1983) Safety Evaluation of Existing Dams, A Water Resources Technical Publication, Denver, Colorado. 41. Virginia State Water Control Board, Bureau of Water Control Management (1983) Safety Evaluation of Small Earth Dams, Information Bulletin 549, Richmond, Virginia. 42. Wilson, S. D., and Handcock, C. W, Jr. (1965) "Instrumentation for Movements Within Rockfill Dams," Instruments and Apparatus for Soil and Rock Mechanics, ASTM STP 392, American Society of Testing Materials, pp. 115-130. 43. Wilson, S. D. (1973)"Deformation of Earth and Rockfill Dams," Embankment-Dam Engineering, Casagrande Volume, John Wiley &Sons, New York. - 63 - APPENDIX D GLOSSARY OF TERMS - 64 - APPENDIX D GLOSSARY OF TERMS ABUTMENT – That part of the valley side against which the dam is constructed. An artificial abutment is sometimes constructed, as a concrete gravity section, to take the thrust of an arch dam where there is no suitable natural abutment. Right and left abutments are those on respective sides of an observer when viewed looking downstream ACT The Dam Safety and Encroachments Act (32 P.S. §§693.1-693.27). AMBERSON DAM – See Buttress Dam. APPURTENANT STRUCTURES – Refers to ancillary features of a dam, such as the outlet, spillway, outlet conduit, tunnels, etc. ARCH DAM – A concrete or masonry dam that is curved in plan so as to transmit the major part of the water load to the abutments. AS-BUILT DRAWINGS – Plans or drawings portraying the actual dimensions and conditions of a dam, dike or levee as it was built. Field conditions and material availability during construction often require changes from the original design drawings. AUXILIARY SPILLWAY – See Spillway. AXIS OF DAM – The plane or curved surface, arbitrarily chosen by a designer, appearing as a line, in plan or in cross section, to which the horizontal dimensions of the dam can be referred. BASE WIDTH (BASE THICKNESS) – The maximum thickness or width between upstream and downstream faces and normal to the axis of the dam but excluding projections for outlets, etc. BEACHING – The removal by wave action of a portion of the upstream (reservoir) side of the embankment and the resultant deposition of this material farther down the slope. Such deposition creates a relatively flat beach area. BERM – A horizontal step or bench in the sloping profile of an embankment dam. BLANKET DRAINAGE BLANKET – A drainage layer placed directly over the foundation material. UPSTREAM BLANKET – An impervious layer placed on the reservoir floor upstream of a dam. In the case of an embankment dam the blanket may be connected to the impermeable element in the dam. BOIL – A disturbance in the surface layer of soil caused by water escaping under pressure from behind a water retaining structure such as a dam or a levee. The boil may be accompanied by deposition of soil particles (usually sand) in the form of a ring (miniature volcano) around the area where the water escapes. BREACH – An opening or a breakthrough of a dam sometimes caused by rapid erosion or a section of earth embankment by water. BUTTRESS DAM – A dam consisting of watertight upstream face supported at intervals on the downstream side by a series of buttresses. Buttress dam can take many forms. ARCH BUTTRESS DAM (BUTTRESS DAM) – A buttress dam that is curved in plan. MULTIPLE ARCH DAM – A buttress dam, the upstream part of which comprises a series of arches. FLAT SLAB DAM (AMBURSEN DAM) (DECK DAM) – A buttress dam is which the upstream part is a relatively thin flat slab usually made of reinforced concrete. - 65 - SOLID HEAD BUTTRESS DAM – A buttress dam in which the upstream end of each buttress is enlarged to span the gap between buttresses. The terms round head, diamond head and tee head refer to the shape of the upstream enlargement. CAVITATION – Wear on hydraulic structures where a high hydraulic gradient is present. Cavitation is caused by the abrupt change in direction and velocity of the water so the pressure at some points is reduced to the vapor pressure and vapor pockets are created. These pockets collapse with great impact when they enter areas of higher pressure, producing very high impact pressures over small areas that eventually cause pits and holes in the surface. Noises and vibrations may be evident during high flows. CONDUIT – A closed channel to convey the discharge through or under a dam. CONSTRUCTION JOINT – The interface between two successive placings or pours of concrete where bond, not permanent, separation is intended. CORE (IMPERVIOUS CORE) (IMPERVIOUS ZONE) – A zone of material of low permeability in an embankment dam; hence the terms central core, included core, puddle clay core and rolled clay core. COREWALL – A wall built of impervious material, usually of concrete or asphaltic concrete in the body of an embankment dam to prevent leakage. See also Membrane or Diaphragm. CREST LENGTH – The measured length of the top of the dam from abutment to abutment includes the length of spillway, powerhouse, navigation lock, fish pass, etc., where these structures form part of the length of the dam. If detached from the dam, these structures should not be included. CREST OF DAM – The crown of an overflow section of the dam. In the United States, the term ''crest of dam" is often used when °top of dam" is intended. To avoid confusion, the terms crest of spillway and top of dam should be used for referring to the overflow section and dam proper, respectively. CRIB DAM – A gravity dam built up of boxes, cribs, crossed timbers, or gabions and filled with earth or rock. CULVERT – (a) A drain or waterway structure built transversely under a road, railway, or embankment. A culvert usually comprises a pipe or a covered channel of box section. (b) A gallery or waterway constructed through any type of dam, which is normally dry but is used occasionally for discharging water; hence the terms scour culvert, drawoff culvert and spillway culvert. CURTAIN – GROUT CURTAIN (GROUT CUTOFF) – A barrier produced by injecting grout into a vertical zone, usually narrow in horizontal width, in the foundation to reduce seepage under a dam. DRAINAGE CURTAIN – See Drainage Wells. CUTOFF – An impervious barrier used to reduce or prevent seepage from passing through the foundation under the dam. CUTOFF TRENCH – The excavation later to be filled with impervious material so as to from the cutoff. Sometimes used incorrectly to describe the cutoff itself. CUTOFF WALL – A wall of impervious material (e.g., concrete, asphaltic concrete, steel sheet piling) built into the foundation to reduce seepage under the dam. DAM – A barrier built across a watercourse for impounding or diverting the flow of water. DESIGN FLOOD – See Spillway Design Flood. DIKE (LEVEE) – A long low embankment. The height is usually less than 4 to 5 meters and the length more than 10 to 15 times the maximum height. Usually applied to embankments or structures built to protect land from flooding. If built of concrete or masonry is usually referred to as a flood wall. Also used to describe embankments that block areas on the reservoir dam rim that are lower than the top of the main dam and that are quite long. - 66 - DIVERSON CHANNEL CANAL OR TUNNEL – A waterway used to divert water from its natural course. The term is generally applied to a temporary arrangement, e.g., to bypass water around a dam site during construction. Channel is normally used instead of canal when the waterway is short. Occasionally the term is applied to a permanent arrangement (diversion canal, diversion tunnel, diversion aqueducts). DRAINAGE AREA – The area that drains naturally to a particular point on a river. DRAINAGE LAYER OR BLANKET – A layer of pervious material in a dam to relieve pore pressures or to facilitate drainage of the fill. DRAINAGE WELLS (RELIEF WELLS) – Vertical wells or boreholes usually downstream of impervious cores, grout curtains or cutoffs, designed to collect and control seepage through or under a dam so as to reduce uplift pressures under or within a dam. A line of such wells forms a drainage curtain. DRAWDOWN – The resultant lowering of water surface level due to release of water from the reservoir. EARTH DAM OR EARTHFILL DAM – See Embankment Dam. EMBANKMENT – Fill material, usually earth or rock, placed with sloping sides. EMBANKMENT-ABUTMENT CONTACT – See Groin. EMBANKMENT DAM – Any dam constructed of excavated natural materials, EARTH DAM (EARTHFILL DAM) – An embankment dam in which more than 50 percent of the total volume is formed of compacted fine-grained material obtained from a borrow area. HOMOGENEOUS EARTHFILL DAM – An embankment dam constructed of similar earth material throughout, except for possible inclusion of internal drains or drainage blankets. Used to differentiate from a zone earthfill dam. HYDRAULIC FILL DAM – An embankment dam constructed of materials, often dredged, that are conveyed and placed by suspension in flowing water. ROCKFILL DAM – An embankment dam in which more than 50 percent of the total volume comprises compacted or dumped pervious natural or crushed rock. ROLLED FILL DAM – An embankment dam of earth or rock in which the material is placed in layers and compacted by using rollers or rolling equipment. ZONED EMBANKMENT DAM – An embankment dam, the thickness of which is composed of zones of selected materials having different degrees of porosity, permeability and density. EMERGENCY GATE – A standby or reservoir gate used only when the normal means of water control is not available. EMERGENCY SPILLWAY – See Spillway. ENERGY DISSIPATOR – Any device constructed in a waterway to reduce or destroy the energy of fastflowing water. FACE – With reference to a structure, the external surface that limits the structure, e.g., the face of a wall or dam. FAILURE – An incident resulting in the uncontrolled release of water from an operating dam. FILTER (FILTER ZONE) – A band or zone of granule material that is incorporated in a dam and is graded (either naturally or by selection) so as to allow seepage to flow across or down the filter without causing the migration of material from zones adjacent to the filter. FINGER DRAINS – A series of parallel drains of narrow width (instead of a continuous drainage blanket) draining to the downstream toe of the embankment dam. - 67 - FLASHBOARDS – Lengths of timber or steel placed on the crest of a spillway to raise the retention water level but that may be quickly removed in the event of a flood either by a tripping device or by deliberately designed failure of the flashboards or their supports. FLOOD PLAIN – An area adjoining a body of water or natural stream that has been or may be covered by flood water. FLOOD ROUTING – The determination of the attenuating effect of storage on a flood passing through a valley, channel or reservoir. FOUNDATION OF DAM – The natural material on which the dam structure is placed. FREEBOARD – The vertical distance between a stated water level and the top of a dam. FUSE PLUG SPILLWAY – See Spillway. GABION – A prefabricated basket or rock within a wire cage that is free drainage and capable of being stacked. GABION DAM – Name given to a crib dam when built of gabions. GATE – In general, a device in which a leaf or member is moved across the waterway from an external position to control or stop the flow. GRADIENT – The rate at which energy is dissipated by virtue of water movement through the soil. GRAVITY DAM – A dam constructed of concrete and/or masonry that relies on its weight for stability. ARCH GRAVITY DAM – An arch dam where part of the water thrust is transmitted to the abutments by horizontal thrust and part to the foundation by cantilever action. CURVED GRAVITY DAM – A gravity dam that is curved in plan. HOLLOW GRAVITY DAM (CELLULAR GRAVITY DAM) – A dam that has the outward appearance of a gravity dam but that is of hollow construction. GROIN – That area along the contact (or intersection) of the face of a dam with the abutments. GROUT A thin cement mortar used to fill voids, fractures or joints in masonry, rock, sand and gravel, and other materials. As a verb it refers to filling voids with grout. Grout is usually applied under pressure. HEEL OF DAM — The junction of the upstream face of a gravity or arch dam with the foundation surface. In the case of an embankment dam, the junction is referred to as the upstream toe of the dam. HEIGHT OF DAM — The vertical measurement expressed in feet as measured from the downstream toe of the dam at its lowest point to the elevation of the top of the dam. HYDRAULIC HEIGHT — Height to which the water rises behind a dam and the difference between the lowest point in the original streambed at the upstream toe of the dam and the maximum controllable water surface. HYDROGRAPH — A graphical representation of discharge, stage or other hydraulic property with respect to time for a particular point on a stream. IMPERVIOUS CORE — See Core. INCLINOMETER (INCLOMETER) — An instrument, usually comprising of a metal or plastic tube inserted in a drill hole, and sensitized monitor either lowered into the tube or fixed within the tube. The instrument is used to measure slope movements at various depths below the ground surface. INTAKE — Any structure in a reservoir, dam, or river through which water can be drawn into an aqueduct. INTERNAL EROSION — See Piping. INUNDATION MAP — A map delineating the area that would be inundated in the event of a dam failure. LEFT ABUTMENT — The abutment on the left-hand side of an observer when looking downstream. - 68 - LEVEE — See Dike. MASONRY DAM — Any dam constructed mainly of stone, brick or concrete blocks that may or may not be jointed with mortar. A dam having only a masonry facing should not be referred to as a masonry dam. MAXIMUM CROSS SECTION OF DAM — Cross section of a dam at the point where the height of the dam is a maximum. MAXIMUM WATER LEVEL The maximum water level, including the flood surcharge the dam is designed to withstand. MEMBRANE (DIAPHRAGM) — A sheet or thin zone or facing made of a flexible impervious material such as asphaltic concrete, plastic concrete, steel, wood, copper, plastic, etc. A cutoff wall, or core well, if thin and flexible, is sometimes referred to as a diaphragm wall or diaphragm. MORNING GLORY SPILLWAY — See Spillway. NORMAL WATER LEVEL (NORMAL POOL) — For a reservoir with a fixed overflow spillway crest, it is the lowest level of that crest. OBSERVATION WELL — Small diameter perforated vertical tube installed within an embankment. Used to measure the height of the internal water surface in the embankment at the location of the well. OGEE SPILLWAY — See Spillway. ONE-HUNDRED YEAR (100-YEAR) FLOOD – The flood magnitude expected to be equaled or exceeded on the average of once in 100 years. It may also be expressed as an exceedance frequency with a one percent change of being exceeded in any given year. OUTLET – An opening through which water can be freely discharged for a particular purpose from a reservoir. OVERFLOW DAM (OVERTOPPABLE DAM) – A dam designed to be overtopped without failing. OWNER – any person who owns, controls, operates, maintains or manages a dam or reservoir, water obstruction or encroachment. PERMEABILITY – A material property which defines the capacity to transmit water. PERVIOUS ZONE – A part of the cross section of an embankment dam comprising material of high permeability. PHREATIC SURFACE – The free surface of water within an earth or rockfill dam. PIEZOMETER – An instrument for measuring pore water pressure within soil, rock or concrete. PIPING – The progressive development of internal erosion by seepage, appearing downstream as a hole or seam discharging water that contains soil particles. PLUNGE BASIN (PLUNGE POOL) – A natural or sometimes artificially created pool that dissipates the energy of free-falling water. The basin is located at a safe distance downstream of the structure from which water is being released. PORE PRESSURE – The internal cellular pressure of water within a mass of soil, rock or concrete. PROBABLE MAXIMUM PRECIPITATION (PMP) – The maximum amount and duration of precipitation that can be expected to occur on a drainage basin. PROBABLE MAXIMUM FLOOD (PMF) – The flood that may be expected from the most severe combination of critical meteorological and hydrologic conditions that are possible in the region. RANDOM FILL – Earth or rockfill, the grading of which is not specified and that is placed without treatment just as it comes from the excavation. RELIEF WELLS – See Drainage Wells. - 69 - RIGHT ABUTMENT – The abutment on the right-handed side of an observer when looking downstream. RIPRAP – A layer of large uncoursed stones, broken rock, or precast blocks placed in random fashion on the upstream slope of an embankment dam, on a reservoir shore, or on the sides of a channel as protection against wave and ice action. ROCK FILL DAM – See Embankment Dam. SADDLE DAM – A subsidiary dam of any type constructed across a saddle or low point on the perimeter of a reservoir. SCARP – The nearly vertical, exposed earth surface created at the upper edge of a slide or a beached area along the upstream slope SEEPAGE – The movement of water that may take place through the dam, its foundation or its abutments. SEEPAGE COLLAR – A projecting collar, usually of concrete, built around the outside of a pipe, tunnel or conduit, under an embankment dam, to lengthen the seepage path along the outer surface of the conduit. Sometimes referred to as "anti-seepage collar. SEMI-IMPERVIOUS ZONE – A zone of relatively low permeability. See Transition Zone. SHELL – The upstream and downstream parts of the cross section of a zoned embankment dam on each side of the core or core wall. SLIDE – The movement of a mass of earth and/or down a slope. In embankments and abutments, this involves the separation of a portion of the slope from the surrounding material. SPILLWAY – A structure over or through which flood flows are discharged. If the flow is controlled by gates, it is considered a controlled spillway, if the elevation of the spillway crest is the only control, it is considered an uncontrolled spillway. AUXILIARY SPILLWAY (EMERGENCY SPILLWAY) – A secondary spillway designed to operate only during exceptionally large floods. FUSE PLUG SPILLWAY – A form of auxiliary or emergency spillway comprising a low embankment or a natural saddle designed to be overtopped and eroded away during a very rare and exceptionally large flood. MORNING GLORY SPILLWAY – See Shaft Spillway. OGEE SPILLWAY (OGEE SECTION) – An overflow weir in which in cross section the crest, downstream slope and bucket have an S or ogee form of curve. The shape is intended to match the underside of the nape at its upper extremities. PRIMARY SPILLWAY (PRINCIPAL SPILLWAY) – The principal or first-used spillway during floodflows. SADDLE SPILLWAY – A spillway constructed at a low saddle on the perimeter of a reservoir. SERVICE SPILLWAY A principal spillway used to regulate reservoir releases additional to or in lieu of the outlet. SHAFT SPILLWAY (MORNING GLORY SPILLWAY) – A vertical or inclined shaft into which flood water spills and then is conducted through, under or around a dam by means of a conduit or tunnel. If the upper part of the shaft is splayed out and terminates in a circular horizontal weir, it is termed a bellmouth or morning glory spillway. SIDE CHANNEL SPILLWAY – A spillway, the crest of which is roughly parallel to the channel immediately downstream of the spillway. SIPHON SPILLWAY – A spillway with one or more siphons built at crest level. This type of spillway is sometimes used for providing automatic surface-level regulation within narrow limits or when considerable discharge capacity is necessary within a short period of time. - 70 - SPILLWAY CHANNEL – A channel conveying water from the spillway crest to the river downstream. SPILLWAY CHUTE – A sloping spillway channel. SPILLWAY DESIGN 'FLOOD (SDF) – The largest flood that a given project is designed to pass safely. The reservoir inflow discharge hydrograph used to estimate the spillway discharge capacity requirements and corresponding maximum surcharge elevation in the reservoir. STAFF GAUGE – A device marked in feet used to indicate and measure water levels. STILLING BASIN – A basin constructed to dissipate the energy of fast-flowing water, e.g., from a spillway or bottom outlet, and to protect the river bed from erosion. STOPLOGS– Large logs or timbers or steel beams placed on top of each other with their ends held in guides on each side of a channel or conduit to provide a cheaper or more easily handled means of temporary closure than a bulkhead gate. STORAGE – The retention of water or delay of runoff either by planned operation, as in a 'reservoir, or by temporary filling of overflow areas, as in the progression of a flood crest through a natural stream channel. SURVEY MONUMENT – A point established on or in the vicinity of an embankment. Provides a set point to survey and, over time, will indicate whether any movement has taken place. TAILWATER LEVEL – The level of water in the discharge channel immediately downstream of the dam. TOE OF DAM – The junction of the downstream face of a dam with the ground surface. Also referred to as downstream toe. For an embankment dam, the junction of the upstream face with a ground surface is called the upstream toe. TOP OF DAM – The elevation of the uppermost surface of a dam, usually a road or walkway, excluding any parapet wall, railings, etc. TOP WIDTH (TOP THICKNESS) – The thickness or width of a dam at the level of the top of the dam. In general, the term thickness is used for gravity and arch dams and width is used for other dams. TRANSITION ZONE (SEMI-IMPERVIOUS ZONE) – A part of the cross section of a zoned embankment dam comprising material whose grading is of intermediate size between that of an impervious zone and that of a permeable zone. TRASH RACK – A screen comprising metal or reinforced concrete bars located in the waterway at an intake to prevent the ingress of floating or submerged debris. UNDERSEEPAGE (FOUNDATION SEEPAGE) – The movement of water through a foundation. UPLIFT – (a) The upward water pressure on the base of a structure. (b) An upstream force on a structure caused by frost heave or wind force. VALVE – A device fitted to a pipeline or orifice in which the closure member is either rotated or moved transversely or longitudinally in the waterway to control or stop the flow. VOLUME OF DAM – The total space occupied by the materials forming the dam structure computed between abutments and from the top to the bottom of a dam. WATERSHED DIVIDE– The divide or boundary between drainage areas. WEIR – A low dam or wall built across a stream to raise the upstream water level. Termed fixed-crest weir when uncontrolled. A structure built across a stream or channel for the purpose of measuring flow. Sometimes described as measuring weir or gauging weir. Types of weir include broadcrested weir, shaped-crested weir, ogee weir and V-notched weir. ZONED EARTHFILL – See Embankment Dam. - 71 - APPENDIX E SUBJECT INDEX - 72 - SUBJECT INDEX Page Abutment Leakage or Seepage 20 Boil Bulging 20 19 Concrete Cracking Deterioration Inspection Items Cracks or Cracking In Concrete In Soil Crest Misalignment Crest Settlement 28 28 29 28 14 28 14 14 15 Debris Outlet Gate Spillway 21 24 21 Embankment Inspection Maintenance Embankment-Abutment Contact Emergency Action Plan Erosion Adjacent to Outlet Conduit At Embankment-Abutment Contact Behind Riprap Downstream Face Spillway Channel 12 12 33 17 43 16 26 19 16 20 21 Failures Hydraulic Seepage Structural 3 3 3 4 Hazard Potential Category I, II, and III 43 Inspection Checklists Checklist Form Embankment Abutment and Foundation Crest Downstream slope Upstream Slope Equipment Miscellaneous Areas Concrete and Concrete Dams Metalwork Monitoring Devices Reservoir Outlet Works Pennsylvania Requirements Photographs Preparation Records Spillway Erodible Channels Non-erodible Channels 8 31 51 12 20 14 18 16 9 27 28 28 27 27 24 8 31 9 31 21 21 22 Page Maintenance Embankment Instructions Items Access Roads Concrete Conduit Earthwork Electrical Hydraulic Mechanical Monitoring Devices Rodent Control Vandalism Prevention Vegetation Control Winterizing Miscellaneous Outlet Conduit Records Schedule Spillway 33 33 42 34 38 36 36 36 37 37 36 38 34 39 34 39 34 34 39 39 33 Metalwork Inspection Items 28 28 Monitoring Devices Inclinometers Inspection Items Maintenance Items Observation Wells Piezometer Survey Monuments Weirs 4 5 27 38 5 38 5 6 Operations Plan Outlet Works Control Works Damage Inspection Items Maintenance Pipe Damage Valve Leakage 41 24 25 24 34 24 24 Pennsylvania Inspection Requirements Puddling on Crest 8 15 Reservoir Slopes Riprap Broken Down or Deteriorated Erosion Behind Rodent Control Ruts on Crest 11 16 16 16 34 15 Seepage and/or Leakage Abutment Clear Concrete Dam Concrete Spillway Exiting as a Boil in the Foundation Muddy Outlet Conduit Sinkholes, Depressions, Animal Burrow 18 20 18 30 23 20 18 26 15 - 73 - Page Slide, Slump or Slip Downstream Slopes Reservoir Slopes Spillway slopes Upstream Slopes Spillway Inspection Items Maintenance 16 19 27 21 16 21 21 33 Trash Rack 36 Vegetation Control Excessive 20 34 20 Whirlpool 17 Commonwealth of Pennsylvania Department of Environmental Protection An Equal Opportunity Employer 3140-BK-DEP2139 Rev. 3/2015 For more information, visit www.dep.state.pa.us, keyword: Dam Safety. -