ACI-210.1R-1994-R1999.pdf
ACI 210.1 R-94 Compendium of Case Histories on Repair of Erosion-Damaged Concrete in Hydraulic Structures Reported by ACI Committee 210 (Reapproved 1999) Stephen B. Tatro Chairman Patrick J. Creegan Angel E. Herrera James R. Graham Richard A . Kaden This report is a companion document to ACI 210R. It contains a series of case histories on hydraulic structures that have been damaged by erosion from various physical mechanical and chemical actions. Many of these structures have been successfully repaired. There were many examples to select from; however, the committee has selected recent, typical projects, with differing repair techniques, to provide a broad range of current exper- ience. These case histories cover only damage to the hydraulic surfaces due to the action of water, waterborne material or chemical attack of concrete from fluids conveyed along the hydraulic passages. In addition to repairs of the damaged concrete, remedial work frequently includes design modi- fications that are intended to eliminate or minimize the action that pro- duced the damage. This report does not cover repair of concrete damaged by other environmental factors such as freeze-thaw, expansive aggregate, or corroding reinforcement. Keywords: abrasion; abrasion resistance; aeration; cavitation; chemical attack; concrete dams; concrete pipes; corrosion; corrosion resistance; deterioration; erosion; grinding (material removal); high-strength concrete hydraulic structures; maintenance; outlet works; penstocks; pipe linings; pipes (tubes); pittings; polymer concrete; renovating; repairs; sewers; spillways; tolerances (mechanics); wear. CONTENTS Chapter l-Introduction, p. 210.1R-1 Chapter 2-Cavitation-erosion case histories, p. 210.1R-2 Dworshak Dam Glen Canyon Dam Lower Monumental Dam Lucky Peak Dam Terzaghi Dam Yellowtail Afterbay Dam Yellowtail Dam Keenleyside Dam ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in designing, plan- ning, executing, or inspecting construction and in preparing specifications. References to these documents shall not be made in the Project Documents. If items found in these documents are desired to be part of the Project Docu- ments, they should be phrased in mandatory language and incorporated into the Project Documents. James E. McDonald Ernest K. Schrader Chapter 3-Abrasion-erosion case histories, p. 21O.lR-13 Espinosa Irrigation Diversion Dam Kinzua Dam Los Angeles River Channel Nolin Lake Dam Pine River Watershed, Structure No. 41 Pomona Dam Providence-Millville Diversion Structure Red Rock Dam Sheldon Gulch Siphon Chapter 4-Chemical attack-erosion case histories, p. 210.1R-25 Barceloneta Trunk Sewer Dworshak National Fish Hatchery Los Angeles Sanitary Sewer System and Hyperion Sewage Treatment Facility Pecos Arroyo Watershed, Site 1 Chapter 5-Project reference List, p. 210.1R-32 CHAPTER 1-INTRODUCTION This compendium of case histories provides informa- tion on damage that has occurred to hydraulic structures and the various methods of repair that have been used. ACI Committee 210 has prepared this report to help oth- ers experiencing similar problems in existing work. Knowledge gained from these experiences may help ACI 210.1R-94 became effective Nov. 1.1994. Copyright 8 1994, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by any elec- tronic or mechanical device, printed, written, or oral, or recording for sound or visual reproduction for use in any knowledge or retrieval system or device, unless permission in writing is obtained from tbe copyright proprietors. 210.1R-1 Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 01:37:58 MSTNo reproduction or networking permitted without license from IHS -,-,- 210.1R-2 ACI COMMITTEE REPORT avoid oversights in design and construction of hydraulic structures and provide guidance in the treatment of future problems. Erosion of concrete in hydraulic structures may occur as a result of abrasive action, cavitation, or chemical attack. Damage may develop rapidly after some unusual event such as a flood or it may develop gradually during normal continuous operation or use. In most cases where damage has occurred, simply replacing the eroded con- crete will ensure immediate serviceability, but may not ensure long-term performance of the structure. There- fore, repair work usually includes replacing eroded concrete with a more resistant concrete and additional surface treatment, modifying the design or operation of the structure to eliminate the mechanism that produced the damage, or both. A detailed discussion of mechan- isms causing erosion in hydraulic structures, and recommendations on maintenance and repair, is con- tained in ACI 210R. When damage does occur to hydraulic structures, repair work poses some unique problems and is often very costly. Direct access to the damaged area may not be possible, or may be limited by time, or other con- straints. In some cases, such as repair to spillway stilling basin floors, expensive bulkheads and dewatering are required. It may not be possible to completely dry the area to be repaired or maintain the most desirable temperature. A great deal of planning and scheduling for repair work are normally required, not only for the repairs and access, but also for control of water releases and reservoir levels. If time permits, extensive inves- tigation usually precedes planning and scheduling to determine the nature and extent of damage. Hydraulic model studies may also be necessary to evaluate possible modifications in the design or operation of the facility. This compendium provides the history on 21 projects with hydraulic erosion damage. They vary in size and cover a variety of problems: 8 with cavitation damage, 9 with abrasion-erosion damage, and 4 with erosion damage from chemical attack. Table 1.1 summarizes the projects. Each repair was slightly different. Each history includes background information on the project or facil- ity, the problem of erosion, the selected solution to the problem, and the performance of the corrective action. Histories also contain references and owner information if further details are needed. CHAPTER 2-CAVITATION-EROSION CASE HISTORIES DWORSHAK DAM North Fork, Clearwater River, Idaho BACKGROUND Dworshak Dam, operational in 1973, is a straight-axis concrete gravity dam, 717 ft high, 3287 ft long at the crest, and contains 6,500,000 cubic yards of concrete. In addition to two gated overflow spillways, three regulating outlets, 12 ft wide by 17 ft high, are located in the spill- way monoliths. The inlet elevation for each regulating outlet is 250 ft below the maximum reservoir elevation. Each outlet jet is capable of a maximum discharge of 14,000 fij/s. Outlet surfaces are reinforced structural concrete placed concurrently with adjacent lean, large aggregate concrete. Coatings to the outlet surfaces were applied during the original construction. In Outlet 1, the wall and invert surfaces from the tainter gate to a point 50 ft downstream are coated with an epoxy mortar having an average thickness of % in. The same area of Outlet 2 was coated using an epoxy resin, approximately .05 in. in thickness. Outlet 3 was untreated. The outlets were operated intermittently at various gate openings for a period of 4 years between 1971 and 1975, resulting in a cumulative discharge duration of approximately 10 months. The three outlets were not operated symmetrically; outlets 1 and 2 were used pri- marily. PROBLEM Inspection in 1973 showed minor concrete scaling of the concrete wall surfaces of Outlets 1 and 2. One year later, in 1974, serious erosion had occurred at wall surfaces of both outlets immediately downstream of the wall coatings, 50 ft from the tainter gate. Part of this wall area had eroded to a depth of 22 in., exposing and even removing some No. 9 reinforcing bars. In the wall sur- faces downstream of Outlet 1 medium damage, up to 1 in. depth of erosion, also occurred in over 60 square yards of surface, bordered by lighter erosion. Every horizontal lift joint (construction joint) along the path of the jet, showed additional cavitation erosion. SOLUTION Repairs were categorized as three types: ?Areas with heavy damage, with erosion greater than 2 to 3 in., were delineated by a 3-in. saw cut and the interior concrete excavated to a minimum depth of 15 in. (Fig. 2.1 and 2.2). Reinforcement was reestablished and steel fiber-reinforced con- crete (FRC) was used as the replacement material. ? Areas with medium damage, where the depth of erosion was less than 1 in., were bush-hammered to a depth of % to 1 in. and dry-packed with mortar. The mortar, if left untreated, would easily have failed when subjected to the high velocity discharge. ?Areas with minor damage, surfaces showing a sand- blast texture, were not separately treated prior to polymer impregnation. The entire wall surfaces of Outlet 1 were then treated by polymer impregna- tion from the downstream edge of the existing epoxy mortar coating to a distance 200 ft down- stream. Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 01:37:58 MSTNo reproduction or networking permitted without license from IHS -,-,- REPAIR OF EROSION DAMAGED HYDRAULIC STRUCTURES 210.1 R-3 TABLE 1.1- SUMMARY TABLE OF PROJECTS COMPRISING THIS REPORT Reference page 210.1R-2 Year completed Location Owner Problem Repair type 1974 Gravity dam Idaho Corps of CavitationPolymer Engineers impregnation 1964 Arch dam Arizona Bureau of Cavitation Aeration Reclamation Project name Dworshak Dam Glen Canyon Dam 210.1R-5 Lower Monumental Dam 210.1R-6 61969 1956 1960 1966 Navigation lock washington Corps of Cavitation Epoxy Engineers Outlet structure Idaho Corps of Cavitation various Engineers Outlet structure British Columbia B.C. Hydro Cavitation Hydraulic Authority redesign Stilling basin Montana Bureau of Cavitation Various overlays RecIamation 1966 1968 Stilling basin Montana Bureau of Cavitation Aeration and RecIamationoverIays I Outlet structure I British Columbia B.C. Hydro I Cavitation High-strength AuthorityI Iconcrete Lucky Peak Dam210.1R-8 Terzaghi Dam210.1R-9 Yellowtail Afterbay Dam 210.1R-11 Yellowtail Dam 210.1R-11 210.1R-12Keenleyside Dam Espinosa Irrigation Diversion Dam 1984 Diversion dam New Mexico 1965 Stilling basin Pennsylvania Soil Conser- vation Service Corps of Engineers Abrasion Abrasion Steel plate armor Silica fume concrete 210.1R-13 210.1R-15Kinzua Dam Los Angeles River Channel 210.1R-17 71940s Channel California 1963 Stilling basin Kentucky Proposed Channel Colorado Corps of Engineers Corps of Engineers SoiI Conser- vation Service Abrasion Abrasion Abrasion Siiica fume concrete Hydraulic redesign High-strength concrete NoIin Lake Dam210.1R-18 Pine River Watershed, Structure No. 41 210.1R-19 Pomona Dam 1963 1986 1969 1991 1976 1960s Varies Stilling basin Kansas Diversion dam Utah Stilling basin Iowa Syphon outlet Wyoming Pipeline Puerto Rico Concrete tanks Idaho Sewerage California structures Corps of Abrasion various Engineers Soil Conser- Abrasion Surface hardener vation Service Corps of Abrasion Underwater Engineers concrete Soil Conser- AbrasionPolymer-modified vation Service mortar Puerto Rico Chemical attack PVC lining Aqueduct 2) backfilling large cavities in sandstone foun- dation with concrete; 3) reconstructing tunnel lining; 4) grinding and patching of small defective areas; 5) remov- ing about 500 cubic yards of debris from lower reaches of tunnel and flip bucket; and 6) constructing an aeration device in the lining upstream of the vertical elbow. Sandstone cavities were filled with tremie concrete be- fore the lining was replaced. About 2000 cubic yards of replacement concrete was used. The aeration slot was modeled in the Bureau of Reclamation Hydraulic Labor- atory to ensure that its design would provide the per- formance required. The aeration slot was constructed on the inclined por- tion of the tunnel approximately 150 ft upstream from the start of the elbow. A small 7-in-high ramp was con- structed immediately upstream of the slot. The slot was 4 by 4 ft in cross section and extended around the lower three-fourths of the tunnel circumference (Fig. 2.4). All repairs and the slot were completed in the summer of 1983. PERFORMANCE Because of the moderate runoff in the Colorado River since completion of the tunnel repairs, it has not been Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 01:37:58 MSTNo reproduction or networking permitted without license from IHS -,-,- 210.1R-6 ACI COMMITTEE REPORT Fig. 2.3-Glen Canyon Dam. Erosion of spillway tunnel invert and sandstone foundation rock downstream of the elbow necessary to use the large spillway tunnels. However, shortly after completion of the work, another high runoff period permitted performance of a field verification test. This test lasted 72 hr with a maximum flow during that time of 50,000 ft3/S. The test was conducted in two phases with several interruptions in each for examination of the tunnel Offsets were intentionally left in place to evaluate whether the aeration slot would indeed preclude cavitation and attendant concrete damage. The tunnel re- pairs and air slot performed as designed. No sign of cavi- tation damage was evident anywhere in the tunnel. Aera- tion has decreased the flow capacity of the spillway tunnels by approximately 20 percent of the original flow capacity. REFERENCES Burgi, P.H., and Eckley, M.S., “Repairs at Glen Can- yon Dam,” Concrete International, American Concrete Institute, MI, V. 9, No. 3, Mar. 1986, pp. 24-31. Frizell, K.W., “Glen Canyon Dam Spillway Tests Model - Prototype Comparison,” Hydraulics and Hydro- logy in the Small Computer Age, Proceeding of the Spe- cialty Conference, Lake Buena Vista, Florida, Aug. 12-17, 1985, American Society of Civil Engineers, New York, 1985, pp. 1142-1147. Frizell, K.W., “Spillway Tests at Glen Canyon Dam,” U.S. Bureau of Reclamation, Denver, CO, July 1985. Pugh, C.A., “Modeling Aeration Devices for Glen Canyon Dam,” Water for Resource Development, Proceed- ings of the Conference, Coeur dAlene, Idaho, Aug. 14-17, 1984, American Society of Cii Engineers, New York, 1984, pp. 412416. CONTACT U.S. Bureau of Reclamation P.O. Box 25007, Denver Federal Center Denver, CO 80225 LOWER MONUMENTAL DAM Snake River, Near Kaloutus, Washington BACKGROUND Lower Monumental Dam
