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Index A abutments, 189 defects, 218 defined, 309-310 deformation, 196-200 leakage, 189, 196 piping, 13 amphibolite, 136 strength, 140 (table) anchor block (see block) anhydrite, 136 defects, 143 (table) strength, 140 (table) animal damage, 251 (see also rodent damage) seepage, 189, 196 antecedent reservoir level, 97 sliding, 13, 17 Apishapa Dam, Colorado, 76 (figure) accelerograms, 171, 172 (figure), 176 (see appurtenant structures also earthquakes, acceleration) corrosion, 19 accidents (see dam accidents) defects, 260-263 (table) edit, defined, 310 defined, 259, 310 aeolian soils, 160-161 (figure), 166 evaluation matrix, 260-263 (table) aerial photography, 23, 68-69 remedial measures, 260-263 (table) afterbay dam, defined, 310 (see also (see also diversion works; gates; Drum Afterbay Dam) outlet works; spillways; trash age of dam racks) dam incidents, 4-5, 7 (figure), 18-20 hazard rating criteria, 51 (table) A-horizon soils, 158 Alabama (see Logan Martin Dam; Walter F. George Dam) Alaska (see Granite Creek Dam) alkali-aggregate reactions, 18-19, 202- 203, 208 alluvial (fluvial) soils, 163-165 Ambursen dam (flat slab dam), 185 (figure), 312 (see also buttress dams) 339 aqueduct, defined, 310 arch dams, 185-187 abutments, 189 accidents, 12 (table) defined, 310-311 earthquake loading, 177 extrados, 196-197, 315 failures, 9 (figure), 12 (table) stability analysis, 205 thrust, 189, 196 (figure), 197 (see also Malpasset Dam, France; multiple arch dams)

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340 Arizona (see Daggs Dam) ash, 136 defects, 143 (table) asphalt linings, 145, 229-230, 232 asphaltie concrete, 21S-216, 228-229 asphaltie slurry walls, 244 Austria (see Eberlaste Dam) automatic warning systems, dam failure, 279 (see also emergency action plans) average exceedanee interval (AEI), 53 axis of dam, defined, 311 B backwater curve, defined, 311 Baldwin Hills Dam, California, 76 (figure), 145, 148 (figure) bank storage (see storage) basalt, 136 defects, 143 (table) strength, 140 (table) base of dam flow, 94, 96 width, defined, 311 batter, defined, 311 beam and cantilever method, gravity dam analysis, 204-205 Bearwallow Dam, 163 bedding planes, 141, 144, 189 bentonite, 229 grout curtain, 237 reservoir seepage correction, 275 slurry, 230, 239, 240 (figure), 242-244 berm defined, 311 seepage control, 235-236 B-horizon soils, 158-159 blanket defined, 311 drainage, 311 grouting, 312 impervious zone, 237 upstream, 311 block, defined, 311 Brazil (see Oros Dam) breeeia, 134 Buffalo Creek Dam, West Virginia, 78 (figure) Index buttress dams, 185 (figure) accidents, 12 (table) defined, 312 failure, 9 (figure), 12 (table) (see also Ambursen dam; gravity dams; multiple arch dam) buttressing rock, 199 C clay California concrete gravity dam, abutments, 199-201 concrete gravity dam, strengths, 208 risk assessment, index-based proee- dures, 49 (see also Baldwin Hills Dam; Drum Afterbay Dam; Hell Hole Dam; Henshaw Dam; Nacimiento Dam; Paeoima Dam; Pilacritos Dam; Rush Meadows Dam; San Fernando Valley dams; San Leandro Dam; San Luis Dam; San Pablo Dam; Santa Felicia Dam; Spaulding Dam; St. Francis Dam) camber, 58, 229 (see also freeboard) carbonate rocks, 134-135 Castlewood Dam, Colorado, 76 (figure) cavitation, 201-202 conduits, 266 gate areas, 269 channel routing, 95-97, 102-103, 104 (table), 105, 196 chert, 145, 147 C-horizon soils, 158-159, 162 civil defense emergency notification of officials, 36-37 evacuation plans, 37 (see also Defense Civil Preparedness Agency) dispersive, 167, 169 linings, 228-229, 275 elaystone, 136-137 defects, 143 (table) strength, 140 (table) Claytor Dam, Virginia, 200 Clemson Lower Diversion Dam, South Carolina, 243

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Index cofferdams, defined, 312 See also Union- town Cofferdam) colluvial soils, 165-166 Colorado See Apishapa Dam; Castlewood Dam; Mt. Elbert Forebay Reser- voir; Schaeffer Dam) concrete density, 202, 210 lift, defined, 312 linings, 228-229 quality, 201-204 steel-fiber, 204 strength, 202, 206, 210 See also asphaltic concrete; rollcrete; shotcrete) concrete and masonry dams accidents, 11-12 (tables) alkali-aggregatereactions,18-19,202- 203,208 causes of defects, 190-195 (table),280- 281 (table) cracks, l9 deterioration, 201-203 earthquake loading, 177 earthquakes, 206-207 evaluation matrix, 190-195 (table) failures, 6-10 (figures), 11-12 (tables) instrumentation monitoring,270,280- 281 (table), 282-284, 305, 306 (figure) remedial measures, 188-189,190-195 (table) types, 183-188 See also arch dams; buttress dams; gravity dams) Condit Dam, Washington, 209-210 conduits corrosion, 267 defective, 218, 261 (table), 266-268 defined, 312 piping, 234 conglomerate rocks, 134, 137 defects, 143 (table) strength, 140 (table) consolidation grouting See blanket, grouting) construction date, 27 faulty, 11-12 (table), 18 materials for emergency repairs, 38 341 Corbara Dam, Italy, 203 core, defined, 312 costs construction/direct, 65, 66 (figure), 69 (table) risk costs, 45-47, 65,66 (figure), 69 (table) total expected, 65, 66 (figure), 69 (table) costs of remedial measures, 55-56 Creager formula, 73-75 crest of dam, defined, 313 crib dams, defined, 313 See also timber crib dams) "crown" effect, 58 crystalline rocks, 159, 162 culvert, defined, 313 curtains See blanket; drainage wells; grouting, curtain) cutoff trench, 163, 235-237 defined, 313 D Daggs Dam, Arizona, 234 dam accidents causes, l l-12 (tables) defined, It (table) dam break analyses, 32-33, 100-103, 104 (table), 105, 129-131 dam failures age of dam, 4-5, 7 (figure), 18-20 chemical action, l9 concrete and masonry dams, 5, 6-10 (figures), 11-12 (tables) cracking of concrete, l9 defined, 302 deformation, ll-12 (tables), 17 deterioration, 11-12 (tables), 17-18 "domino effect," 33 earthfill dams, 5, 6-10 (figures), 14-16 (tables) flood flow formulas, 75-77 flow erosion, ll-12 (tables) foundation defects, 6-7 (figures), ll-12 (tables) gate, ll-12 (tables), 18 height of dam,5,8 (figure), 57 ICOLD surveys, 5, 6-10 (figures), 11-12 (tables), 18

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342 modes, 7-16 (tables), 17-18, 32-33, 46-47,51-52 overtopping, 5,6-7 (figures),10,11-12 (tables), 14 (table) peak discharges, 76 (figure), 78 (figure) piping and seepage, 5, 6-7 (figures), 11-12 (tables) probability, 5, 10 (figure) "triggering', cause,6-9, 11-12 (tables), 14 type of dam, 5, 9-10 (figures), 11-12 (tables) USCOLD surveys, 5-6- 11-12 (tables), 18 Dam Safety Program (see National Dam Inspection Act) dam size classification, 82 (table) dams Apishapa Dam, Colorado, 76 (figure) Baldwin Hills Dam, California, 76 (figure), 145, 148 (figure) Bearwallow Dam, 163 Buffalo Creek Dam, West Virginia, 78 (figure) Castlewood Dam, Colorado, 76 (figure) Claytor Dam, Virginia, 200 Clemson Lower Diversion Dam, South Carolina, 243 Condit Dam, Washington, 209-210 Corbara Dam, Italy, 203 Daggs Dam, Arizona, 234 Drum Afterbay Dam, California, 202-203 Dworshak Dam, Idaho, 200-201, 204 Eberlaste Dam, Austria, 243 E1 Infiernillo Dam, 303, 305 (figure) Granite Creek Dam, Alaska, 76 (figure) Gwinnett County Dam, Georgia, 33 Hatchtown Dam, Utah, 76 (figure) Hebgen Dam, Montana, 18 Helena Valley Dam, Montana, 164 (figure) Hell Hole Dam, California, 76 (figure) Henshaw Dam, California, 227 Indiantown Reservoir, Florida, 239, 240 (figure) Island Park Dam, Idaho, 62-65, 66 (figure), 67 Jackson Lake Dam, 60-61,62-63 (figures) Index Johnstown Dam, Pennsylvania, 78 (figure) Kortes Dam, Wyoming, 199 Koyna Dam, India, 206-207 Kranji Dam, Singapore, 243 Laguna Dam, Mexico, 243 Laurel Run Dam, Pennsylvania, 78 (figure) Libby Dam, Montana, 204 Little Deer Creek Dam. Utah, 76 (figure) Logan Martin Dam, Alabama, 145, 147 Malpasset Dam, France, 77, 78 (figure), 148,149 (figure), 196 Mohicanville Dam, Ohio, 229 Mt. Elbert Forebay Reservoir, Colorado, 239, 241 Nacimiento Dam, California, 265 Oahe Dam, South Dakota, 166 Oros Dam, Brazil, 76 (figure) Pacoima Dam, California, 207 Pilacritos Dam, California, 219 Razaza Dam, Iraq, 242-243 Rush Meadows Dam, California, 203 San Fernando Valley Dam, California, 18, 219 San Leandro Dam, California, 227 San Luis Dam, California, 21D, 255 San Pablo Dam, California, 227 Santa Felicia Dam, California, 266 Shaeffer Dam, Colorado, 76 (figure), 78 (figure) Sheffield Dam, California, 219 Spaulding Dam, California, 210-211 St. Francis Dam, California, 76 (figure), 78 (figure), 134 Swift Dam, Montana, 76 (figure), 78 (figure) Table Rock Dam, 299 (figure) Teton Dam, Idaho, 8, 31, 76 (figure), 78 (figure), 148 Two Medicine Dam, Montana, 76 (figure) Uniontown Cofferdam, Ohio, 150 Vaiont Reservoir/Dam, Italy, 272, 273 (figure) Waco Dam, Texas, 144-145, 146-147 (figures), 300-301 (figures) Walter F. George Dam, Alabama, 243 Willow Creek Dam, Montana, 67-68, 69 (table)

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Index Willow Creek Dam, Oregon, 209 Wolf Creek Dam, Kentucky, 243 data collection and analysis concrete and masonry dams, 305-306 (table) embankment dams, 299-301 (figures), 302, 303 (figure), 304 (table), 305 (figure) decision analysis, 41-42 categories of dams, 44-45 criteria conflicts, 45 "do nothing" approach, 43, 56 "nonterminal" decisions, 44 "reference alternative," 43, 56 "terminal' decisions, 44 Defense Civil Preparedness Agency's National Warning System (NAWAS), 36 deformation abutments, 196-200 dam incidents, 11-12 (tables), 17 measurements, 295 (table) See also modulus of deformation) degree-day method, snowmelt flood analysis, 94 design data, 26-27, 72 standards, 56 deterioration dam incidents, 11-12 (tables), 17-18 instrumentation monitoring, 284 diabase, 137 defects, 143 (table) strength, 140 (table) diaphragm earth dams, 215 dike, defined, 313 discharge capacity, increasing, 106-107, 108 (figure) See also floods and flooding, peak discharges) dispersive clays, 167, 169 "ditch', method, slurry wall construction, 242 diversion works, 259, 310, 314 See also upstream, diversion facilities) Dnieper Power Station, 245-246 Dniester Power Development, 246 dolerite, 137 dolomite, 134, 135 (figure), 137 defects, 143 (table) strength, 140 (table) 343 dolosse, defined, 314 '~domino effect" See dam failures, "domino effect") downstream development, 4, 106-107, 110-111 dam design standards, 79-80 flood flow formulas, 77 hazard potential, 28 drainage areas, defined, 314 blankets, 228-229, 237, 314 galleries, 197, 201 systems, instrumentation monitoring, 282 wells, 13, 237, 314 zones, 213-214 drains cleaning, 207 defective, 247-248, 262 (table), 269 finger, 315 toe, 237 See also trench drains) drawdown, defined, 314 See also rapid drawdown) Drum Afterbay Dam, California, 202-203 dunes, 160-161 (figure), 166 Dworshak Dam, Idaho, 200-201, 204 earthfill dams causes of defects, 280-281 (table) defined, 314 diaphragm earthfill dams, 215 displacements, 303 (figure) earthquake loading, 177-178 foundation requirements, 217 homogeneous, 213-214, 235-236, 314 hydraulic fill dams, 214, 314 instrumentation monitoring, 304 (table) remedial measures, 228-229 stonewall-earth dams, 215 zoned, 214-215, 235, 315 See also embankment dams) earthquakes abutment deformation, 198-199 acceleration, 171, 173, 174 (table), 175 (figure), 176 (table), 177, 255 appurtenant structures, 270-271

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344 attenuation, 179, 180 (figure) concrete and masonry dams, 206-207 dam effects, 173, 175 epicenter, 171, 180 (figure), 315 instability, 11 (table), 18 Koyna, India (1967), 206-207 loading conditions, 253, 254 (table), 255-256 Madison Valley, Montana (1959), 18 magnitude, 171, 174-181 maximum credible earthquake (MCE), 173, 176 (table), 179, 320 operating basis earthquake (OBE), 173, 176 (table), 179, 321 reservoir-induced, 177, 274, 289, 294 Richter scale, 309 risk assessment, 54-55 San Fernando Valley, California (1971), 18, 207, 219 San Francisco, California (1906), 169 San Leandro Dam, California, 227 (see also headings beginning with the word seismic) Eberlaste Dam, Austria, 243 E1 Infiernillo Dam, 303, 305 (figure) embankment-abutment contact, 230-231 embankment dams accidents, 11 (table) classification, 213 "crown" effect, 58 defects, 218-219, 220-226 (table), 227 defined, 314-315 drains, 247-248 evaluation matrix, 220-226 (table) failures, 6-10 (figures), 11 (table), 14-16 (tables) flow erosion, It (table), 12 foundations, 16 (table), 217-218 instrumentation monitoring, 280-281 (table), 284-287, 299,301 (figures), 302, 303 (figures), 304 (table), 305 (figure) leveling the top, 58 overtopping, 14 (table), 58, 245 pipingandseepage, 12-13, 15-16 (table) remedial measures, 218, 220-226 (table) stability analysis, 228, 251-257 structural failures, 16 (table) types, 213-217 Index emergency action plane, 35 defined, 315 guidelines, 31-32, 129-131 news releases, 37 notification plans, 36-37, 39 remedial measures, 59-60 time available for response, 35 emergency potential, evaluation, 32-39 emergency repairs, 38 emergency spillway (see spillways) Emerson Crumb test, dispersive clays, 169 energy-budget method, snowmelt flood analysts, 94 epicenter, 171, 180 (figure), 207,315 epoxy coatings, 196, 201-202,210,266 facings, 203 mortar, 204 erosion appurtenant structures, 269-270 dam defects, causes of, 262-263 (table) dispersive clays, 167, 169 flow, 11-12 (tables) toe, 14 (table) wave action, 13, 14 (table), 230-231 (see also cavitation; headcutting; slope erosion) evacuation plans, 37-38 inundation maps, 33 notification of personnel, 39 exceedance interval, defined, l00-year, 84 (table) (see also average exceedance interval) extrados, arch dams, 196-197, 315 extrusive rocks, 133 F Faber inflatable dam, 109 facings concrete, 228 defined, 315 "unite membrane, 244 rockfill dams, 215-217, 244-245 steel-reinforced, 265 synthetic materials, 203 timber, 216, 244-245 factors of safety, loading conditions, 253, 254 (table), 257

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Index failures (see dam failures) faults,141,144 abutment areas, 189 San Francisco earthquake (1906),169 See also earthquakes) Federal Emergency Management Agency (FEMA), 2-3, 32 fetch, defined, 315 fibrous concrete See concrete, steel-fiber) filters, defined, 315 finite element method, stability analysis, 205,210 Dashboards, 109, 210, 315-316 flat slab dam See Ambursen dam) flooding flood plain management, 60,316 flood surcharge, defined, 316 flood wall, defined, 316 hydrographs, 90-91, 319 land, permission to flood, 275 loading, 205-206 peak discharges, historical and regional comparisons, 73,74 (figure), 75 probability, 53-54 risk assessment, 53-54 routing, defined, 316 snowmelt, 93-94 studies, sources of, 72 U.S. historical records, 53-54 See also average exceedance interval; channel routing; dam failures; hydrographs; inundation maps; probable maximum flood; spillway design flood) Florida See Martin County Power Plant Cooling Pond Dike) flows defect detection, means of, 280-281 (table) erosion, 11-12 (tables) meters, 295 (table) flumes, 293 (figure), 295 (table) fluvial soils (see alluvial soils) focus (hypocenter), 316 foliation planes, 141, 144 foundation defined, 316 embankment dams, 217, 219, 222 (table), 227 treatments, 217-218 345 foundation-embankment interface, 218, 248-249 foundation failures, 132 earth dams, 16 (table) leakage, 6-7 (figure), 11-12 (tables) slides, 13, 16 (table), 17 fracture, defined, 144 France See Malpasset Dam) freeboard, 99-100, 229, 249 defined, 316 parapets, 247 freeze-thaw action abutment deformation, 198 concrete deterioration, 18-19,202 reservoir damage, 275-277 fuse plug spillways, 57, 108 (figure), 324 gabions, 199, 231, 238, 247, 316 galleries, 199, 317 See also drainage, galleries) gates defective, 218, 260-262 (table), 268-270 defined, 317-318 failures, 11-12 (tables), 18 (`see also spillways) Georgia See Gwinnett County Dam) geotextiles, 231-232, 237-239, 240 (figure), 241 glacial soils, 160-161 (figure), 166-167 Weiss, 137 defects, 143 (table) strength, 140 (table) grain size, 152 (figure) See also soil classification, textural) granite, 137 defects, 143 (table) strength, 140 (table) Granite Creek Dam, Alaska, 76 (figure) gravity dams, 183-188 abutments, 189, 199-200 accidents, 12 (table) beam and cantilever method, 204-205 bedding planes, 189 defined, 318 earthquake loading, 177 failures, 5, 9 (figure), 12 (table) foundation, 135 (figure)

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346 gravity method, 204-205 stability analysis, 204-206 trial-load twist analysis, 204-205 gravity-transported soils, 165-166 groin, defined, 318 ground motion analyses, 171-181 (see also seismic, zones) grout curtains, 19, 237, 249 grouting, 196, 199-200 blanket, 312 consolidation, 312 contact, 312 curtain, defined, 313 foundation seepage, 237 reservoir seepage, 275 gunite, 202 facings, 216, 244 parapet walls, 247 Gwinnett County Dam, Georgia, 33 gypsum, 13S, 137 defects, 143 (table) H fIatchtown Dam, Utah, 76 (figure) hazard, defined, 318 hazardmitigation,42, 48, 106-110 hazard potential classification, 4, 31 downstream development, 28 evaluation, 32-33, 35 inundation maps, 33, 34 (figure), 35 headcutting, 67-68 /tsee also erosion) headrace, defined, 318 headwater estimates, 206 level,318 Hebgen Dam, Montana, 18 heel of dam, 318 height of dam dam failures, relationship, S,8 (figure), 57 defined, 318-319 Helena Valley Dam, Montana, 164 (figure) Hell Hole Dam, California, 76 (figure) Henshaw Dam, California, 227 hoists, defective, 260 (table), 268-269 Index homogeneous earthfill dams, 213-214 defined, 314 seepage control, 235-236 settlement, 229-230 transverse cracking, 235-236 hydraulic fill dams, 214, 314 hydrograph defined, 319 flood, 90-91, 319 unit, 95-96 ice, 275-277 Idaho risk assessment of dams, 49 See also Dworshak Dam; Island Park Dam; Teton Dam) igneous rocks, 132-133 impervious core rockfill dams, 216-217 incidents (see dam accidents; dam failures) inclinometers, 286, 295 (table), 319 independent arch theory, 205 India (see Koyna Dam) Indiantown Reservoir, Florida, 239, 240 (figure) inflow design flood (IDF), 62, 65-66, 68-69 "injection method," slurry wall construc- tion,242 inspection programs frequency, 20-21, 23, 38, 59 informal observations, 20, 23-24 maintenance inspections, 20, 23 need for additional investigations 29-31 records development, 25 safety site inspections, 28 technical inspections, 20-23 types of inspections, 20 See also maintenance programs; monitoring programs; National Dam Inspection Program) instrumentation, 278-279 data collection and analysis, 299-301 (figures), 302, 303 (figure), 304 (table), 305 (figure) geotechnical, 295 (table) installation methods, 295, 297-298

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Index manufacturers, 295-297 (tables) suppliers, 295-297 (tables) types of, 294-295 See also monitoring programs) intensity scale, defined, 319 See also Mercalli intensity scale) Interagency Committee on Dam Safety (ICODS),32 International Commission on Large Dams (ICOLDJ, dam incidents survey, 5,6-10 (figures), 18 intrados, defined, 319 inundation maps, 33 classification of areas, 33, 35 defined, 319 emergency action plans, 129 remedial measures, 60 risk assessment, 47 sample, 34 (figure) Iraq See Razaza Dam) Island Park Dam, Idaho, 62-65, 66 (figure), 67 Italy See Corbara Dam; Vaiont Reservoir/Dam) Jackson Lake Dam, 60-61, 62-63 (figures) JohnstownDam, Pennsylvania, 78 (figure) joints, 141, 144-145 defect measurements, 280-281 (table) K karst, 135, 145 Kentucky See Wolf Creek Dam) Kortes Dam, Wyoming, 199 Koyna Dam, India, 206-207 Kranji Dam, Singapore, 243 L Laguna Dam, Mexico, 243 landslides (see slides and sliding) Laurel Run Dam, Pennsylvania, 78 (figure) leakage abutment, 189,196 347 defined, 319 foundation, 11-12 (tables), 13 instrumentation monitoring,282,284- 285 See also piping; seepage) Libby Dam, Montana, 204 limestone, 134-135, 137 defects, 143 (table) strength, 140 (table) . . . .mmgs asphalt, 145 asphaltic concrete, 228-229 clay, 228-229 concrete, 228-229 defined, 319 membrane, 239, 241 polyvinylchloride (PVC), 275 vegetated, 264 liquefaction earthquake loading, 60-61, 62 (figure) foundation during earthquakes, 55 Little Deer Creek Dam, Utah, 76 (figure) loading conditions concrete dams, 205 (figure) defined, 320 hydrologic load, 46 risk assessment factor, 46-47 safety factors, 204 seismic loading, 46 static reservoir load, 46 loam, 152, 153 (figure) loess, 160-161 (figure), 166 log booms, 265 Logan Martin Dam, Alabama, 145, 147 loss rates, 94 M maintenance programs, 24-25 See also inspection programs, maintenance programs) Malpasset loam, France, 77, 78 (figure), 148, 149 (figure), 196 maps, sources, 169 See also inundation maps) marble, 135 marl, 137, 160-161 (figure) defects, 143 (table) strength, 140 (table)

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348 Martin County Power Plant Cooling Pond Dike, Florida, 243-244 Martin-Marietta Sodyeco Chemical Plant Waste Lagoon Dike, North Carolina, 244 masonry dams (see concrete and masonry dams) maximum credible earthquake (MCE), 173, 176 (table), 179 Mercalli intensity scale, 171, 174 (table) metamorphic rocks, 135-136 Mexico (see Laguna Dam) micaceous rock, 138 defects, 143 (table) micrometer gage readings, 208 Mississippi, dams, erosion problems, 167 Mississippi River Valley, aeolian soils, 166 mitigation measures (see hazard mitigation) modes of dam failure (see dam failures, modes) modulus of deformation, 186, 199 modulus of elasticity, 140 (table), 186-187, 202, 210 Mohicanville Dam, Ohio, 229 monitoring programs, 59 concrete and masonry dams, 270, 280-281 (table), 282-284, 305 (figure), 306 (table) embankment dams, 280-281 (table), 284-287, 299-301 (figures), 302, 303 (figure), 304 (table), 305 (figure) instrumentation installation, 295, 297-298 need, 29-30 reservoirs, 280-281 (table), 287-293 (see also inspection programs) Montana (see Hebgen Dam; Helena Valley Dam; Libby Dam; Swift Dam; Two Medicine Dam (Lower); Willow Creek Dam) monuments, 283, 285-286, 302 movements means of detection, 280-281 (table) measurement, 283-286 Mt. Elbert Forebay Reservoir, Colorado, 239, 241 multiple arch dams, 188 (figure) defined, 312 stability analysis, 207-208 (see also arch dams) Myer formula, 73-75 Index N Nacimiento Dam, California, 265 National Dam Inspection Act (PL 92-367), 4-5, 20, 44, 48, 81 National Program of Inspection of Nonfederal Dams, 81-82 National Warning System (NAWAS), 36 National Weather Service (NWS) dam break models, 102-103, 104 (table), 105, 129-131 storms, 72, 93 North Carolina dam failure, 164 risk assessment, index-based procedures, 49 (see also Martin-Marietta Sodyeco Chemical Plant Waste Lagoon Dike) notification plans (see emergency action plans) Nuclear Regulatory Commission (NRC) PMF peak discharges, source, 75 o Oahe Dam, South Dakota, 166 observation wells, 289 (figure), 295 (table) Ohio (see Mohicanville Dam) Ohio River (see Uniontown Cofferdam) operating basis earthquake (OBE), 173, 176 (table), 179, 321 Oregon (see Willow Creek Dam) Oros Dam, Brazil, 76 (figure) outlet works, 259 defective, 218, 260 (table) obstructions, 265-266 siphons, 268 outlets defined, 321 low-level, 98 overtopping, 245-247 dam failures, 5, 6-7 (figures), 10, 11-12 (tables), 14 (table) designing for, 106-107, 110 failure score, 49-50 remedial measures, 245 risk assessment, 49-50, 61, 62-63 (figures) (see also spillways)

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Inaex p Pacific Gas and Electric Company concrete dams, sealing materials, 203 Spaulding dams, California, 210-211 timber facings repair, 245 Pacoima Dam, California, 207 parapet walls, 109, 229, 247, 265, 321 parshall flume, 293 (figure) peak flows defined, 321 maximum peak flows equation, 77, 78 (figure) pegmatite, 138 defects, 143 (table) strength, 140 (table) Pennsylvania, risk assessment of dams, 49 (see also Johnstown Dam; Laurel Run Dam) penstock, defined, 321 peridotite, 138 defects, 143 (table) photographs construction of dam, 25 damage cost assessments, 68-69 inspection programs, 22-23, 284 phreatic surface, defined, 321 phyllite, 138 strength, 140 (table) piezometric readings/piezometers, 20-22, 38, 149, 233, 239, 243, 272, 286-288, 295 (table), 299-301 (figures) defined, 321 frequency of readings, 304 (table) seepage analysis, 254 Pilacritos Dam, California, 219 Pinhole test, for dispersive clays, 169 piping, 233-234, 243-244 dam incidents, 5, 6-7 (figures), 8-9, 11-12 (tables), 15 (table) defined, 321 embankment dams, 11 (table), 13, 15 (table) foundation, 11-12 (tables), 15 (table) (see also leakage; seepage) plunge basin, defined, 321 plutonic rocks, 132-133 Point Loma landslide, California, 293 (figure) Poissons ratio, 202 349 polymers, 203 (see also geotextiles; synthetic fabrics) polysulfide, 203 pore pressures, 218-219, 280-281 (table) defined, 322 instrumentation, 295 (table) precipitation (see probable maximum precipitation) pressure relief wells (see relief wells) probable maximum flood (PMF), 68-69 defined, 54, 84 (table), 322 estimates, 89-90, 93 flood risk assessment, 53-54 peak discharges, 75, 76 (figure), 77, 78 (figure), 114-121 snowmelt floods, 93-94 probable maximum precipitation (PMP) defined, 322 distribution to basin subareas, 90-91 hydrographs, 91 hydrometeorological reports, 88 (figure) seasonal variations, 90 storm data, 122-124 (figures), 125-128 (tables) storms, result of, 93 time distribution, 91 protective armors, 245-246 pseudostatic methods of analysis (see seismic analysis) pulse velocity measurements, 202 pumice, 133, 138 defects, 143 (table) strength, 140 (table) pyrites, 202-203 Q quartzite, 135, 138 defects, 143 (table) strength, 140 (table) R radio communication systems, 37 rainfall, measurements, 280-281 (table) (see also probable maximum precipitation) rapid drawdown, 218-219, 227 lining failure, 228

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350 loading condition, 253, 254 (table), 255 slope instability, 227 Razaza Dam, Iraq, 242-243 records of dam, 25, 28-29 recreation areas emergency notification of users, 37 hazard potential, 33, 35 relief walls (see drainage, wells) remedial measures appurtenant structures, 260-263 (table) embankment dams, 218, 220-226 (table) initiation, 39 modifications of the dam, 56-57 nonstructural, 55, 59-60 overtopping, 245-247 reservoir seepage, 274-275 slope erosion, 231-233 spillway modifications, 57 status quo alternative, 56 structural, 55-59 reservoirs area, 322 causes of defects, 280-281 (table) defined, 322 failures, 132 induced earthquakes, 177, 274, 289, 294 instrumentation monitoring, 280-281 (table), 287-288, 289-293 (figures), 306 level, 97, 227, 321 loading conditions, 46 regulation, 59 routing, 98-99, 104 (table), 105, 322 sedimentation, 273-274 seepage, 274-275 storage capacities, increasing, 106, 108-109 surface, 322 residual soils, 158-159, 160-161 (figure), 162-163 residuum clayey, 162 conglomerate, 163 sandstone, 163 resins, 204 epoxy-based, 203 polyester-based, 203 (see also sealing materials) response spectra, 171, 175-176, 177 (figure), 207 Index revetments, 231-232 Richter scale, 322-323 riprap, 13, 19, 231, 238, 241, 245, 269 defined, 323 risers, 266 risk analysis/risk assessment analytical (probability) approach, 52 case studies Island Park Dam, Idaho, 62-65, 66 (figure), 67 Jackson Lake Dam, 60-61, 62-63 (figures) Willow Creek Dam, Montana, 67-68, 69 (table) defined, 323 earthquakes, 54-55 empirical (historical frequency) approach, 52 floods, 53-54 formal (quantitative) assessment, 45-46 format, 46-47 index-based (qualitative) procedures, 45, 49-50 judgmental approach, 41-42, 52 methodology, 43-47 models, 47-49 probabilistic approach, 41-43, 52 qualitative approach, 45, 49-50 quantitative approach, 45-46 role in dam safety, 41-43 screening procedures, 47-49 static loading, 51-52 subjective process, 45 risk costs of dam failure, 46-47, 65, 66 (figure), 68, 69 (table) defined, 323 rock anchor, 323 rock bolts, 199, 323 rock classification, 132-136 rock strength, 140 (table) rock types, 136-138 defects, 141, 143 (tables), 144 geologic age, 141 mode of deposition, 141 physical properties, 139, 140 (table), 141, 143 (tables), 144 specific gravity, 140 (table) rockfill dams causes of defects, 280-281 defined, 213, 314

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Index displacements, 303 (figure) faced, 215-217, 244-245 foundation requirements, 217-218 impervious core, 216-217 seepage control, 235, 236 settlement, 230 steel-reinforcement, 246-247 timber facings repair, 244-245 rockfilled crib dams (see timber crib dams) rodent damage, 24, 218, 236-237 rollcrete, 209, 323 rolled fill dams, defined, 314-315 routing (see channel routing; reservoir routing) rubble (see talus) rubble dam, 323 runoff diversions, 106-107, 109 models, 94-96 Rush Meadows Dam, California, 203 S safety evaluation, 25, 30 construction data, 27 design data, 26-27 federal guidelines, 31 maintenance records, 27-28 operating records, 27-28 report of findings, 29 Safety Evaluation of Existing Dams (SEED), 49-SO, 51 (table) San Fernando Valley dams, California, 18, 219 San Leandro Dam, California, 227 San Luis Dam, California, 219, 255 San Pablo Dam, California, 227 sand filters, 196 sandstone, 134-135, 138 defects, 143 (table) strength, 140 (table) Santa Felicia Dam, California, 266 scaling, 199, 202 Schaeffer Dam, Colorado, 76 (figure), 78 (figure) schist, 135, 138-139 defects, 143 (table) strength, 140 (table) scree (see talus) 351 sealing materials, 196 conduits, 266-267 reservoirs, 275 sedimentary rocks, 133-135 sedimentation, 273-274 seepage, 233-237 abutment areas, L89, 196 alluvial soils, 164 concrete dams, 189, 196 dam defects, 218 dam failures, 6-7 (figures), 8-9, 14-16 (table) defined, 323 embankment dams, 6-7 (figures), 14-16 (table), 235-237 foundation, 217-218, 236-237 hazard rating criteria, 51 (table) instrumentation, 282, 284-285, 295 (table) loading condition, 253, 254 (table) reservoir defect, 274-275 (see also leakage; piping) seiche, 54 . . seismic analyses, 256-257 intensity scale, 171, 174 (table), 319 loading, 46, 54-55, 257 measurements, 280-281 (table), 284 reservoir loading, 274, 289, 294 zones, S1 (table), 168 (figure), 170 (figure), 171, 172 (figure), 207 seismographs, 289, 294 seismometers, 289, 294 sensitivity analysis, 65-66 serpentine, 139 defects, 143 (table) settlement conduit foundations, 267 embankment dams, 218, 229-230 measurements, 303 (figure) shale, 134, 139 defects, 143 (table) strength, 140 (table) shear strength evaluation, 256 loading condition, 254 (table), 256 shear zones, 141, 144 abutment areas, 189 Sheffield Dam, California, 219 shortcrete, 216

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352 sill, 324 siltstone, 134, 139 defects, 143 (table) strength, 140 (table) Singapore (see Kranji Dam) siphon spillway (see spillways) slab-and-buttress dams (see buttress dams) slate, 139 defects, 143 (table) strength, 140 (table) slides and sliding, 262, 263 (figure), 272-273 concrete and masonry dams, 11-12 (tables) embankment dams, 11 (table), 13, 16 (table), 17 flow slide, 16 (table) foundation slide, 13, 16 (table), 17 gravity dams, 207-211 landslide materials, 165-166 notification of highway officials, 39 reservoirs, 272, 273 (figure), 288-289 slope, defined, 324 slope erosion downstream, 231-232 embankment dams, 218 remedial measures, 231-233 slope instability, 218-219, 251-253 causes, 227 reservoirs, 272-274, 288-289 slope protection, 233 damage, 11 (table), 13 defined, 324 upstream, 231-232 vegetative, 232 slurry trench, defined, 324 slurry walls, 237 bentonite, 239, 240 (figure) "injection"/vibrated beam method, 242 installation, 241-244 "trench" construction method, 242-243 snowmelt floods, 93-94, 96-97 soil classification, 151 descriptive, 151-152, 153 (figure) engineering, 152, 154-157 (figures) geologic, 151, 160-161 (figure), 169 pediologic, 151, 152, 169 textural, 151 Unified Soil Classification System, 152, 154-157 (figures) Index Soil Conservation Service (SCS) dam break models, 101-102, 104 (table), 105 dispersive clay test, 169 flood studies, 72 spillway capacity guidelines, 81-82 soils, 149-163 aeolian, 160-161 (figure), 166 A-horizon, 156 alluvial (fluvial), 163-165 B-horizon, 158-159 C-horizon, 158-159, 162 classification, 151, 152-157 (figures), 158 cohesive, 227 colluvial, 165-166 glacial, 160-161 (figure), 166-167 map sources, 169 survey maps, 169 residual, 158-159, 160-161 (figure), 162-163 tests for dispersive clays, 163 transported, 160-161 (figure), 163-167 sonic velocity measurements, 202, 210, 280-281 (table), 298 South Carolina (see Clemson Lower Diversion Dam) South Dakota (see Oahe Dam) Southern California Edison Company, concrete dam sealing materials, 203 Spaulding dams, California, 210-211 specific gravity, rock, 140 (table) spillways capacity criteria, 77-83, 84 (table) defective, 260 (table) defects, 218, 259-265 defined, 324-325 emergency, 57, 67-68 fuse plug type, 57, 108 (figure), 324 inspection programs, 22 modifications, 57 obstructions, 265-266 siphon, 263-264, 325 slide blockage, 197 stilling basins, 264, 325 (see also gates; overtopping) spillway design flood (SDF), 71, 77-78, 263 defined, 83, 325 envelope curve method, 84-86 frequency-based floods, 84-86

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Index gravity dams, 205-206 hydrologic evaluation guidelines, 84 (table) hydrometeorological method, 84-87 site-specific determinations, 85, 87, 89 stability analyses, 205-206 stability analysis concrete dams, 204-207, 273-274 embankment dams, 228, 251-257 finite element method, 205, 210 methods, 252-253 sedimentation, 273-274 static loading, risk assessment for dam failure, 46, 51-52 steel dam failures, 11 (table) steel reinforcement, 202, 204, 246-247, 265 St. Francis Dam, California, 76 (figure), 78 (figure), 134 stonewall-earth dams, 215 stoplogs, defined, 311 See also log booms) storms antecedent, 93 NWS estimates, 72 PMP estimates, 122-124 (figures), 125-128 (tables) stub towers See risers) Swift Dam, Montana, 76 (figure), 78 (figure) synthetic fabrics, 237-239, 240 (figure), 241 synthetic materials, 203-204, 228-231 T Table Rock Dam, piezometer readings, 299 (figure) tailwater level defined, 325 estimates, 206 talus, 165 TAMS, dam break model, 103, 104 (table) Tennessee Valley Authority (TVA), dam break model, 103, 104 (table) Teton Dam, Idaho, 8, 31, 76 (figure), 78 (figure), 148 Texas See Waco Cam) textural classification See soil classification, textural) 353 thrust See arch dams, thrust) timber facings, 216, 244-245 parapet walls, 247 timber crib dams deterioration, 19 failures, 6 (table), 17 rockfilled, 216-217 toe of dam defined, 326 drains, 15 (table), 237 erosion, 9, 11, 14 (table) piping, 164 weight, 326 transported soils, 160-161 (figure), 163-167 trash racks, 259, 265-266, 269, 276, 326 tree root damage See vegetation) trench, backfilled, 229 See also cutoff trench; slurry trench; slurry walls) trial-load twist analysis, 204-205 "triggering," cause of failure, 6-7, 8 (table), 9, 11-12 (tables) tuff, 139 defects, 143 (table) strength, 140 (table) Two Medicine Dam, Montana, 76 (figure) U Unified Soil Classification System, 152, 154-157 (figures) Uniontown Cofferdam, Ohio, 150 United States Committee on Large Dams (USCOLD) dam and spillway design standards, 79-80 dam incidents survey, 5-6, 11-12 (tables) uplift pressures, 200-201, 207, 234 concrete and masonry dams, 19 defined, 326 drainage system defects, 269 embankment dams, 247-248 instrumentation monitoring, 282-283 measurements, 280-281 (table) slurry walls, 241 upstream diversion facilities, 57-58, 109 slope failure, 16 (table) See also blanket, upstream)

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354 U.S. Army Corps of Engineers dam break models lIagen (uniform procedure), 102, 104 (table) HEC-1, 103, 104 (table), 105 dam safety inspection guidelines, 81 flood studies, 72 Hydrologic Engineering Center (HE C), 103, 104 (table), 105 risk assessment, index-based procedures, 49-50 spillway capacity guidelines, 81-82 See also National Dam Inspection Act (PL 92-367~) U.S. Bureau of Reclamation flood studies, 72 ground motion analyses, 175 (figure) loading, safety factors, 204 risk assessment, 60-61, 62-63 (figures) spillway capacity guidelines, 81-82 See also Safety Evaluation of Existing Dams) Utah (see Hatchtown Dam; Little Deer Creek Dam) V Vaiont Reservoir/Dam, Italy, 272, 273 (figure) vegetation grass slope protection, 232 linings, 264 tree and brush damage, 218, 236-237, 249-251 vibration, 201, 268-269 Index Virginia See Claytor Dam) volcanic rocks, 133, 155 (figure) surface deposits, 155 (figure) W Waco Dam, Texas, 144-145, 146-147 (figures), 300-301 (figures) Walter F. George Dam, Alabama, 243 warning systems, dam failure See emergency action plans; evacuation plans; Defense Civil Preparedness Agency) Washington See Condit Dam) Water Resources Council Interagency Hydrology Committee, 53 watershed divide, 327 modeling, 94-95 wave wall, 327 weirs, 288, 292 (figure), 295 (table) defined, 327 leveling, 58 West Virginia See Buffalo Creek Dam) Willow Creek Dam, Montana, 67-68, 69 (table) Willow Creek Dam, Oregon, 209 Wolf Creek Dam, Kentucky, 243 Wyoming See Kortes Dam) zoned earthfill dams, 214-215, 235, 315