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Jordan Hydroelectric Project New Small Hydro on Corps of Engineers’ Dam

(or how to Strap a Turbine to the Front of a Headgate) Paul Cyr, P.E., Senior Engineering Consultant, Kleinschmidt Associates, United States

James Price, PhD, President, W.V. Hydro and Noah Corporation, United States Andrew Feimster, President North Fork Electric Inc., United States

ABSTRACT The Jordan Hydroelectric Project is a first of its kind hydroelectric project installed on the discharge tower of a USACE flood storage dam. The project involves the installation of two conventional vertical Kaplan turbine-generators, each generating 2.2 MW under 57.5 feet of gross head, located on the upstream side of the discharge tower. Each turbine-generator is installed in a 180-ton steel enclosure that seals to the upstream side of the tower’s intake. While the turbines have a total discharge capacity of 1,100 cfs, the hydroelectric project controls flow releases of up to 3,100 cfs through project equipment. When flows from the dam exceed the hydraulic capacity of the hydro project the equipment is raised to restore the tower to full hydraulic discharge capacity. The project required negligible modifications to the discharge tower and does not affect the Corps’ operation of the tower or control of flow releases. The first turbine was commercially operational in January 2012. The project arrangement could be installed at other dams, USACE or otherwise, that contain a discharge tower. The paper will describe the design of the enclosures and the modifications to the discharge tower needed to accommodate the hydroelectric equipment; it will also identify key development factors that could impact the ability to install or restrict the size of similar projects at other locations. INTRODUCTION The Jordan Dam was constructed in 1982 without the ability to generate hydroelectric power; since then enough water has been released to have generated more than 500,000 MWH of electricity. That all changed on January 20, 2012 when the first of two hydroelectric turbine-generators became commercially operational by generating 2.2 MW of power. The Jordan Dam is located in Moncure, NC, 25 miles southwest of Raleigh, NC. The main dam is a rock-filled structure 113 feet high and 1,200 feet long, owned and

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operated by the United States Army Corps of Engineers for purposes of flood control and water quality for the Haw River. The dam is typical of many flood storage dams, with flows released from a multi-gated, rectangular concrete discharge tower, and discharged into the river via an unpressurized outlet conduit (Figure 1). Under normal pond levels the dam creates a 15,000 acre impoundment, with a gross head of 57.5 feet; with the impoundment at flood control level, the tower’s discharge capacity is 17,000 cfs.

Figure 1: Existing Discharge Tower DESCRIPTION OF HYDROELECTRIC PROJECT The Jordan Hydroelectric Project consists of two vertical Kaplan turbine-generators (65-inch runner), each generating 2.2 MW under a gross head of 57.5 feet and a flow of 550 cfs for an estimated combined annual generation of 16,900 MWH. Each turbine-generator is installed in a 180-ton steel enclosure, the power Module, with the Module located on the upstream side of the discharge tower to seal off the 12 feet wide by 30 feet high intake opening. The Modules are 12 feet square, 77 feet tall from invert to generator floor, and 120 feet tall overall (Figures 2, 3 & 4). Each Module contains two 3 foot wide by 4 foot high Spillgates to discharge flow above the turbine’s capacity. The generators are direct drive, air cooled synchronous units located inside an enclosure at the top of the Module.

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Licensing of the hydroelectric project with the Federal Energy Regulatory Commission began in 1993 with a license received in 1997 and amended in 2006 for the current two unit hydroelectric project. Design and construction documents were submitted to the USACE for review between October 2008 and December 2009, with the project receiving its 408 Permit from the USACE in November 2010 and on-site construction beginning immediately with the construction of a 23 KVA transmission tie.

Figure 2:

PROJECT TEAM The project team included the following organizations:

USACE, Wilmington, NC, dam owner Jordan Hydroelectric Limited Partnership, SC, Developer Kleinschmidt Associates, SC, Structural Designer

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North Fork Electric, Inc., NC, designer, fabricator and lead contractor o Diehl Engineering Company (sub to North Fork Electric), marine engineer

for shaft analyses and bearing requirements Cascade Machinery Vibration Solutions, marine engineer, operational vibration China Huadian Engineering Corporation, China, Turbine-Generators Grainger Underwater Services, IN, fabricator, underwater constructor

The core design and construction team was assembled based on relationships, with the Developer and Kleinschmidt having worked together for 15 years, Kleinschmidt and North Fork Electric having worked together for 10 years, and North Fork Electric and Grainger Underwater Services having working relations exceeding 20 years. Both the Developer and Kleinschmidt had collectively worked on more than eight privately developed hydroelectric projects located at USACE dams prior to the development of the Jordan Hydroelectric Project.

Figure 3

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DESIGN Loading Conditions The Modules are located upstream of the discharge tower’s Emergency and Services gates, in the maintenance bulkhead slots. Under normal operating conditions the head differential on the Modules can vary from 57.5 to 64 feet. The Modules are designed to the same criteria as the USACE’s Service and Emergency gates and are capable of withstanding the hydrostatic loading associated with a flood pool at elevation 240 feet and the tower dewatered (a 90 feet differential.) With the impoundment at flood pool level, the generator would be 6 feet underwater unless the Module is lifted. Designing the Modules to withstand flood pool loadings continues to provide the tower with three lines of water shutoff, and means they are suitable of acting as a maintenance bulkhead, without need to remove them if repairs are needed to the tower or the Emergency or Service Gates.

Figure 4: Module #1 in Low Maintenance position, lifted 56 feet. Temporary

construction barge is located below lower access platform.

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The two turbines have a total hydraulic capacity of 1,100 cfs and with the two spillgates in each Module at full discharge the total hydraulic discharge capacity that can be controlled by the Modules is 3,100 cfs, allowing the hydroelectric project to control the release of flows 86% of the time. Once discharge from the tower is greater than the capacity of the Modules, or the impoundment reaches the level of the uppermost grease bearing floor at elevation 223 feet, the Modules will be raised up to 46 feet and flows released from the tower will then pass beneath the Module and be controlled by the existing Service Gates. It is estimated that the Modules may have to be lifted five times per year for flood releases, but if the turbines could continue operating with the Modules raised three to five feet to discharge flow beneath them, then the amount of time the turbine-generators are out of service due to high flow releases can be reduced. During commissioning of the first Module it was confirmed that power could be generated with a Module in the raised position. Module The 180-ton Modules are fabricated of 50 ksi, hot dipped galvanized steel. The Module is assembled in four distinct sections (Turbine, Flume, Intake, and Generator) as identified in Figure 2. The weight and size of each section was limited to 50,000 pounds to minimize the size of the mobile crane needed to install the Modules. The Turbine Section acts like a headgate and is the only watertight section, sealing the Module to the tower’s 12 foot wide by 35 foot high intake opening. A cage of structural tubing encloses the lower part of the Turbine Section to allow the Module to bear on debris setting on the tower invert without damaging the draft tube whose invert is 12 inches above the tower invert. The cage also protects the draft tube from debris impact when flow is discharged beneath the Module in the raised position. The Module’s Turbine Section is enclosed by removable steel plating to prevent the wicket gate operating mechanisms from being damaged by debris when flow is discharged through the Spillgates. The Module bears on the tower’s invert only along the downstream edge, on the existing steel gate sill. The Module’s intake section is enclosed within fixed trash racks that bear on a concrete slab that forms the roof of the existing concrete grizzly racks (Figure 2). When in the normal operating position, the Kaplan runner is located 5.5 feet above tailwater. The Module’s two spillgates are located above the draft tube and are hydraulically operated. The Spillgates open automatically during a generator load rejection to maintain flow discharges. The gates can also be used to increase the Module’s discharge capacity from the turbine’s capacity of 550 cfs to a total flow of 1,550 cfs. Each Module contains a small hydraulic power unit that is located in the Generator Enclosure to operate the turbine wicket gates, runner blades, and Spillgates.

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Normal Operating Flood Position Maximum Maintenance

Position Lifted 46 feet Lifted 67 feet Figure 5

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A programmable logic controller inside the Generator Enclosure automatically monitors and controls the various systems and may be operated locally or remotely. The Module has two sets of three electrically operated screw jacks located at the generator floor; these are extended to “lock” the generator floor to the discharge tower in order to resist the generator’s short circuit torque of 243,000 foot-pounds (translates to 40,563 pounds at the jacks); the generator’s normal running torque is 51,256 ft-pounds (8,543 pounds at the jacks). The jacks automatically extend themselves upon completion of lowering the Module and automatically retracted prior to lifting a Module. Once installed, the Modules will not be completely removed from the discharge tower unless major work on the lowest 20 feet is required. To remove the lowest fixed part of the turbine (distributor assembly) all turbine-generator components and 75% of the Module must be removed from the bulkhead slots. Lifting System The Module is raised and lowered only under balanced head conditions, with the tower’s Service Gate in the closed position. The Service Gate was modified to include gate position indication and interfaces with the Project’s control systems to ensure that the gate is closed as appropriate to allow the Module to be lowered or raised. The Module is raised by a single hydraulic cylinder rated at 200 tons. The cylinder can apply 50 tons to assist in thrusting closed (down) the Module if necessary. The cylinder engages the Module via a Lifting Carriage that is 12-feet square and weighs 6 tons (Figure 2). The carriage engages the Module’s steel lift blocks via two rotating cam arms that act like the forks of a fork truck; the Module can be lifted by one cam arm. The hydraulic power unit used to operate the lifting cylinder is located inside of the discharge tower. The lifting cylinder can raise the Module 67 feet for maintenance purposes (to raise the turbine runner to the level of the lowest access platform) (Figure 5). The cylinder has a 12 foot stroke and the Module is raised-lowered in increments of 10 feet. At the end of each stroke the Module is supported by two dogging arms that are located on a support beam mounted to the top of the discharge tower (Figure 4). When the Module is lifted, the dogging arms automatically engage the dogging blocks in a ratcheting fashion. When the Module is lowered, the dogging arms are manually rotated via pneumatic cylinders to engage or disengage the dogging blocks. The Module can be supported by one dogging arm. The lifting carriage is normally held in the engaged position with the Module, other than when it is being raised or lowered to move the Module to the next incremental 10 feet of movement.

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The Modules are tended by operating personnel while being raised and lowered, but the lifting controls can be automated to allow an individual from the USACE to raise a Module 10 feet (one stroke of the lifting cylinder) under emergency conditions. The lifting of a Module under emergency conditions would be initiated by a single command entered into the local control computer. The control system would shut down the turbine and apply the generator brakes, closing the tower’s Service Gate and flooding the space between the Module and the gate by opening the Module spillgates; once hydrostatic pressures have been equalized and the screw jacks retracted, the Module will be raised 10 feet. The control system would then open the Service Gate as needed for the USACE to manually control the release of flow from the discharge tower. Ancillary Structures Access to the Module is via two steel platforms that were constructed to support the installation, operation and maintenance of the Module and its equipment. A control booth 10 feet wide and 20 feet long was attached to the side of the discharge tower at roof level to house the operating controls and electrical switchgear. A 4.16 kV to 23 kV totally-enclosed pad mounted step-up transformer was installed on the crest of the dam with all lines entering and exiting the transformer underground. A 48 kVA, propane-powered standby generator was installed to provide power for the operation of the various hydraulic power units needed to raise the Modules and discharge tower’s gates. Tower Modification and Loads To accommodate the Module’s installation, modifications to structural elements of the discharge tower were limited to the removal of a tertiary concrete beam at the top of the tower on the upstream side, and two 13 foot square by 3 feet thick underwater sections of concrete that formed the top of the existing concrete grizzly racks. Structural analyses of the access bridge from the crest of the dam to the top of the discharge tower indicated that the bridge has a structural capacity of 250 tons, more than sufficient to support a maximum load of 50 tons when transporting the generator. To accommodate the installation of the Module, a 90-ton Linkbelt Rough Terrain Crane, GVW 115,000 pounds, was used to provide a lifting capacity of 62,000 pounds at a 20 foot radius. The tower was designed in the 1960s using allowable stress concrete methods for a 30-ton truck crane (GVW 64,000 pounds) traversing the roof while carrying a 26,000 lb load. To allow driving the 90 ton crane onto the roof, the GVW was reduced to 83,000 tons by removal of counterweights, jib boom, crane hook, and allowing only minimum fuel load; and the boom raised to 57 degrees to evenly distribute

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the loads on the axles. Structural analyses performed using current Load Resistance Factor Design methods indicated that that the roof’s load factors were controlled by shear, and the roof under design, current crane loading, and proposed crane loadings had live load factors as follows:

• Design Load, 30T P&H Truck Crane: 1.14 • Current Crane used, 35T Terex RTC: 1.25 • Proposed Crane (stripped), 90T Linkbelt RTC: 1.39

Analyses also indicated that the roof did not have the capacity to support the weight of the crane and the loads to be lifted. To remove the operating crane’s loads from the roof, the crane’s downstream outriggers bear on three 21-inch high steel beams spanning the width of the tower to transfer loads to the tower’s side walls, and the upstream outriggers bear on the support steel that is part of the Module Lifting System with the loads transferred into the tower upstream wall. With the crane supported on steel beams, analyses indicated that the roof had the structural capacity to support the weight of three Module sections above the Turbine section, inclusive of the generator, when the components were strategically located on the roof. A survey of the plumb and square of the discharge tower’s bulkhead slots was taken at one foot increments over the height of the tower from invert to roof. The survey revealed that the distance between piers was narrower than shown on record drawings and the slots were neither plumb nor square to the tower, as 116 foot tall structure was never intended to fit into slots. Modifications were made to the Modules to accommodate the survey results. STARTUP AND CONSTRUCTION The first unit began generation on January 12, 2012 with an output of 2.2 MW at the design head and flow. Unit 2 is expected to be operational in early July 2012. Through April 2012, Unit 1 has generated 3,957 MWH. The unit has operated over a range of flow from 100 to 8,000 cfs, having operated for over three days with the Module raised 3 to 5.5 feet above the tower invert allowing the release of about 1,600 to 3,000 cfs from beneath the Module while still generating 1.8 MW. During the design of the hydroelectric project, the USACE expressed concern about the vibrations that could be produced during turbine operation and the possible impact it may have on the integrity of the discharge tower. Vibration is monitored continuously by the control system and the levels have remained very low, low enough that a penny can be stood on edge on the generator housing and will remain in that position for 30 or more minutes, eventually falling over due to air currents inside of the generator enclosure. Higher vibrations are

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recorded when the unit is offline and water is discharged through the existing tower gates, and the vibrations did not increase if the unit was operated while discharges were occurring through the tower gates. The Module structure, lifting system, and their operating systems have operated as intended, with the lifting system operating more smoothly than expected. The Module has been raised and lowered approximately twenty times, equivalent to four years of operation; it takes one person 60 minutes to raise the module 46 feet to allow unimpeded flood releases, and one person 40 minutes to lower the Module the same distance. Unit output when operating while also discharging flow through one or both spillgates is not affected, rather it is improved due to increased submergence on the draft tube. Since put into operation, Unit 1 has had a down time of approximately 15 days due to broken coupling bolts, insufficient flow to the thrust bearing cooling water pump, and a wicket gate linkage that broke when jammed by debris. The vibration monitoring system tripped the unit for all but the problem with the cooling water. The problem with the cooling water supply was corrected by a high pressure flushing of the oil cooling piping around the bearing. There have been two equipment design problems that have occurred, both related to the turbine-generator equipment. After 19 days of operation, the unit tripped due to over-vibration. Subsequent inspection showed that 5 of 10 coupling bolts had broken just below the lowest grease-lubricated bearing. Through early design work on the Modules, it was recognized that accurate alignment of the turbine, shafting, bearings and generator was impossible. Every time the Module is raised and lowered, the entire shaft/bearing assembly will shift and move out of alignment. Diehl Engineering (experts in ship propulsion alignment) was consulted, and their analysis showed that the long, relatively slender shaft will bend and deflect without overstressing the shaft steel or creating excessive guide bearing reactions. These findings have proven correct with the smooth operation of the Module to date. One oversight was the strength of the coupling bolts supplied by the turbine manufacture. The shafts have typical one-piece forged ridged couplings supplied with ten 43 mm ASTM A668 Class J (65,000 psi yield) bolts. The bending and flexing of the shaft during operation causes a cyclical loading and un-loading of the coupling bolts at each revolution that caused the premature failure of the bolt. The solution was to replace all of the coupling bolts with 12.9 class socket-head bolts (Grade 9 equivalent, 160,000 psi yield) and torqued to a load equal to 70% of yield. The second design problem was associated with wicket gates operation, with the gates moving hesitantly in increments of 20% gate opening. The cause of the problem was torsional back-lash in the 63 foot long wicket gate operating shaft due to insufficient

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rigidity. Rather than replacing the 7.625-inch diameter shaft, the operating shaft was eliminated and the hydraulic servo-cylinder replaced with one located underwater and attached directly to the wicket gate operator ring.

Relations with USACE through the underwater inspections and surveys of the discharge tower, modifications to the discharge tower, and installation of the hydroelectric equipment have been outstanding and their review and oversight team has been very cooperative and supportive of the project. Throughout the whole design and construction process the project team has made USACE personnel welcome in the design review, at the fabrication shops, and on site. The design and construction teams have been upfront, non-confrontational, and pro-active with USACE personnel, taking the philosophy that the discharge tower and dam is their house

. Throughout the on-site construction process, project field personnel freely submitted diver plans and critical lift plans to the USACE, and worked closely with USACE operating personnel in communicating and coordinating the timing and control of flows released from the dam. The USACE personnel who operate and manage the operation of the dam along with the District Commanders have all been impressed and pleased with the level of communication and project personnel doing what they said was going to be done.

The Jordan Hydroelectric Project did not utilize any proprietary or patented design, equipment, or operating systems; although the concept and many of the operating systems were custom designed to fit the site, accessibility, and operating requirements. Many of the concepts of the turbine-generator arrangement could be adapted or installed at other dams, USACE or otherwise, that contain a discharge tower. A hydro installation similar to the Jordan project was installed at the USACE’s Colebrook Dam in Connecticut and it has operated successfully since 1988. The owner of the Jordan Hydroelectric Project is proceeding with a second hydroelectric development at a USACE dam, the Gathright Project in Virginia (FERC No. P-12737), that will contain a single vertical Francis turbine generating 3.7 MW at a hydraulic capacity of 350 cfs and 140 feet of gross head. The unit will be installed in a 175 foot tall, 250-ton, Module that will be placed on the upstream face of the discharge tower, against the 15-feet wide by 70-feet high intake opening. KEY DEVELOPMENT FACTORS In the design and construction of the Jordan Hydroelectric Project, the following key factors were identified as being critical to the ability and success of installing a hydroelectric project similar to the Jordan Project at other discharge towers:

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• Modifications to or removal of any part of the concrete grizzly racks are not required. The racks are normally massive and located well below the impoundment’s water surface and extremely difficult and expensive to modify.

• The discharge tower’s bulkhead slots are located upstream of the tower’s upstream face eliminating any need to remove any part of the upstream wall to accommodate a Module.

• The spacing between piers containing the bulkhead slots is reasonably consistent, and the bulkhead slots are reasonably plumb and square to the tower.

• The tower’s roof and access bridge have the structural capacity to support the loads needed to install the Modules, or means can be implemented to redistribute or redirect the loads so as not to overload the affected structure.

• Being upfront with the owners of the discharge tower about any possible temporary and long term impacts of the hydro project on the structural integrity and operation of the discharge tower is a vital aspect for success.

• Support from the owners of the discharge tower and their belief that the project can be constructed and operated successfully.

• Remembering who the owner of the discharge tower or dam is, and that the structure is their house are also vitals aspects for success.

**************************** BIOGRAPHIES Paul Cyr, P.E., Kleinschmidt Associates A 1979 graduate from Northeastern University with B.S. Civil Engineering, Structural Design. Has been with Kleinschmidt for 35 years and is the Principal-in-Charge for their South Carolina Office. He specializes in dam safety, dam operation, dam and powerhouse design. Paul been involved with the development of the Jordan Hydroelectric Project since 1999, and with the project in the configuration to be discussed since 2006. James Price, W.V. Hydro and Noah Corporation B.S. from University of Tennessee with M.S. and Ph.D. degrees from Ohio State University (1976) in nuclear engineering. Since 1980, Jim has been the President and Chief Engineer of development activities for W.V. Hydro, Noah Corporation, and subsidiaries for conceptual engineering, environmental and financing. Projects developed include hydropower, coal-fired, and waste coal-fired. Fifteen FERC licenses

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issued; three projects are operating, three projects are in construction, three are in development, and balance of licenses were sold. The total capacity of issued licenses is 328 MW.

Andrew Feimster, North Fork Electric Inc. Owner of North Fork Electric Inc. for 20 years. Licensed Electrical Contractor in North Carolina Electrical and Licensed Mechanical Contractor in South Carolina. Certified crane operator, welder, and diver. Has over 30 years experience in the industry, conducting major electrical, mechanical and civil work on over 200 hydro units at over 65 dams. Andy has developed many unique systems and products for use in the hydro industry, including “The Dragrake” trash rake; specialized gates; custom hydraulic, electrical and SCADA systems.