SMALL DAMS PETITS BARRAGES

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Approximately 19 900 m 3 of RCC were placed in the spring of 2000. The RCC mixture contained 163 kg/m 3 Portland cement and 30 kg/m 3 fly ash. On-site USACE personal reported that the spillway has been overtopped at least twice. The first time was during hurricane Ivan on September 16, 2004, and the second on March 27 and 28, 2005. Figure 7.8 was taken during this overtopping event. Figure 7.9 was taken in May 2007 and shows the excellent condition of the RCC steps after the two overtopping events. Fig. 7.8 – A view of principal and auxiliary spillways at Lake Tholocco Dam (Abdo and Adaska/07) Fig. 7.9 – Excellent condition of RCC steps at Tholocco Lake Dam (Abdo and Adaska/07) Red Rock Detention Basin Inlet Spillway (USA) Red Rock Detention Basin, in Nevada, is one of five detention basins and is part of a master plan for providing flood protection and erosion control in Las Vegas Valley. It’s 122
complete construction was in 2001, including an RCC inflow spillway, a holding reservoir, and three outflow spillways (service, auxiliary and emergency). The RCC structure consists of an approach apron starstepped chute, stilling basin and training walls. The spillway is 12,6 m high, and the slope of the chute is 3H:1V. The steps are 0,6 m high. The RCC mixture contained 216 kg/m 3 cement and 44 kg/m 3 fly ash. The RCC spillway operates during every rain event generally a flow in the wash, normally a few times a year. Figure 7.10 shows the inflow water during a 2004 storm. The storm carried heavy sediments loads, evidenced by the presence of a large pile of sediment in the basin of the RCC structure. In 2005 a strong storm deposited boulders up to 91 kg on the RCC steps and distributed the sediment pile throughout the detention basin (Figure 7.11). Although RCC is still a relatively new method of construction for this application (i.e. spillways constructed on embankments or overtopping protection embankments) performance data is limited. Structures that have been overtopped show strong evidence that the RCC has performed satisfactorily when subjected to hydrostatic pressures and flows containing very abrasive sediments, as reported by Abdo and Adaska in 2007. In addition to proper structural design, the primary factors that have contributed to the successful performance of these structures are related to the RCC mix design and sound construction methods, namely; Fig. 7.10 – 2004 storm overview at Red Rock Detention Basin spillway (Abdo and Adaska, 2007) 123
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SMALL DAMS Design, Surveillance and
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FOREWORD The ICOLD - International
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ACKNOWLEDGEMENT The Ad Hoc Committe
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FOREWORD ACKNOWLEDGEMENT SUMMARY TA
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5.5.5 Compaction in confined areas
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7.2.1 Introduction 7.2.2 Spillway c
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1. SMALL DAMS DEFINITION AND CLASSI
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2 Fig. 1.2 - Relationship H . V wit
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1.3 REFERENCES [1] French Committe
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2.3 ZONED EARTHFILL DAMS In arid pa
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sloping core guarantees water impou
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Fig. 2.11 - Hlinky Concrete Gravity
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Fig. 2.13 - Photograph of Neusberg
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The gabion dam as the gabion retain
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Some inflatable dams are operated b
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3.1 INTRODUCTION 3. SAFETY OF SMALL
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Condition Effect on safety 13. Dama
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Fig. 3.2 - Massive dam break overto
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and suffusion or internal instabili
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downstream part of the embankment m
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small dam impounding a lot of water
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Whenever the Supervising Authority
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emergency management organizations
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c) The decommissioning plan should
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5.1 INTRODUCTION 5. FEATURES OF THE
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5.2 DESIGN FLOODS Inadequate flood
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downstream slope will show seepage
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Fig. 5.2 - Design Freeboard 5.4.3 F
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2 U f Fe S 1400 D Where Uf is the d
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Maximum compaction is obtained at c
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characteristic must be determined.
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5.6.1 Foundation Watertightness The
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� A continuous vertical chimney d
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Thickness of pervious layer Thick D
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t 5.7.1.4 Practical Considerations
Page 71 and 72: It is generally accepted that cohes
Page 73 and 74: � Simple Bishop (1955) � Spence
Page 75 and 76: � The elements for surface draina
Page 77 and 78: The supporting layer for the rip-ra
Page 79 and 80: For very small reservoirs (fetch of
Page 81 and 82: The junction of the downstream slop
Page 83 and 84: Fig. 5.14 - Hongshiyan homogenous d
Page 85 and 86: material has been left in place or
Page 87 and 88: The homogeneous dam is recommended
Page 89 and 90: [3] OL and OH soils are not recomme
Page 91 and 92: part (core) lies in the zone (Fig.
Page 93 and 94: 6. GUIDELINES ON SURVEILLANCE OF SM
Page 95 and 96: cases the owner may retain the serv
Page 97 and 98: Surface displacement on an embankme
Page 99 and 100: Fig. 6.1 - Leakage measurement usin
Page 101 and 102: Water Level Sounder - Details of th
Page 103 and 104: pressure) Left abutment 2 5 Weir ga
Page 105 and 106: Fig. 6.9 - Recommended standpipe pi
Page 107 and 108: the others weir gauges need to be i
Page 109 and 110: � Earthquakes sensible at the dam
Page 111 and 112: APPENDIX INSPECTION CHECKLIST FOR S
Page 113 and 114: Exposed reinforcement � The condu
Page 115 and 116: These spillways can be lined or unl
Page 117 and 118: flowing water. Flowing water with h
Page 119 and 120: Fig. 7.3 - Installation of the arti
Page 121: Fig. 7.7 - Dam overtopping protecti
Page 125 and 126: In some cases, the downstream face
Page 127 and 128: Tube-a-manchettes injection system
Page 129 and 130: 7.3.5 Slope Protection Measures 7.3
Page 131 and 132: Pipe Rehabilitation SLIPLINING MODI
Page 133 and 134: Conditions Pros Cons Comments types
Page 135 and 136: Embankment dams that have properly
Page 137 and 138: and minimize erosion. Design of sui
Page 139 and 140: [20] SMEC- “Draft Guidelines for
Page 141 and 142: present visual information. It must
Page 143 and 144: Fig. 8.1 - Three small dams in casc
Page 145 and 146: Social Disruption low (rural area)
Page 147 and 148: Fig. 8.4 - Flood water level after
Page 149: 8.9 REFERENCES [1] BURREC (1994) -
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SMALL DAMS PETITS BARRAGES

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