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HomeMy WebLinkAboutSolomon Gulch Hydroelectric Project Reservior Capacity Increase Feasibility Study 1991SOLOMON GULCH HYDROELECTRIC PROJECT RESERVOIR CAPACITY INCREASE FEASIBILITY STUDY SOLOMON GULCH HYDROELECTRIC PROJECT RESERVOIR CAPACITY INCREASE FEASIBILITY STUDY Prepared for Copper Valley Electric Association P.O. Box 927 Valdez, Alaska 99686 Prepared By HDR Engineering, Inc. 11225 S.E. Sixth Street Building C, Suite 200 Bellevue, Washington 98004 November 1991 SOLOMON GULCH HYDROELECI'RIC PROJECT RESERVOIR CAPACI'IY INCREASE FEA:SmiLI'IY STUDY TABLE OF CONTENTS Section Introduction I. Alternative Descriptions and Recommended Alternative n. Hydrology and Hydraulics m. Energy Production N. Cost Estimate v. Economic Analysis VI. Environmental Concerns and Other Issues vn. Dam Safety vm. License Amendment Requirements IX. Conclusions and Recommendations AIWendices 1. Bridgestone Cost Quotations -Rubber Dam 2. Connection Diagram -2-foot Dam 3. Connection Diagram -5-foot Dam 4. Letter from Bridgestone regarding ic~ performance i ~ 1 2 8 8 9 10 10 13 13 14 SOLOMON GULCH PROJECT RESERVOIR CAPACITY INCREASE PROJECr Introduction HDR Engineering Inc. (HDR) was retained by Copper Valley Electric Association (CVEA) of Valdez, Alaska to study the feasibility of raising the spillway crest on the existing Solomon Gulch Dam by either 2 feet or 5 feet The resulting increase in storage would allow CVEA to operate their hydroelectric generating facilities at Solomon Gulch later into the year and help offset or eliminate the need for supplemental diesel generation on their system. The study by HDR is being conducted in two phases; 1) a pre-feasibility analysis to determine quickly if the project makes sense economically and to identify any fatal flaws; and 2) a more detailed feasibility study to be conducted only in the event that the Phase I study indicates a viable project This report is confined to the presentation of the findings of only the Phase I study. Background: The Solomon Gulch Hydroelectric Project, FERC #2742, is located on the south shore of Valdez Harbor about 4 miles southeast of the City of Valdez. The project was originally owned by CVEA and was constructed between 1978 and 1982. In 1982, the project was purchased by the Alaska Power Authority, now the Alaska Energy Authority (AEA). The project is operated by CVEA through an agreement with AEA. Solomon Lake is impounded by a asphaltic concrete faced rock:fill dam with a concrete ogee spillway with a crest elevation of 685 feet msl. The reservoir impounded by the dam is about 640 acres in area with a live storage of approximately 31,000 acre-feet Two 48- inch pipelines approximately 3,800 feet long carry· water to the powerhouse, which is located adjacent to tidewater at the shore of Valdez Harbor. The powerhouse has two vertical shaft Francis units which operate over the range of 645 to 590 feet of head and have a total installed capacity of 12 MW. The project provides power for the City of Valdez and Glennallen community via a transmission intertie. In addition to the Solomon Gulch Hydroelectric Project, the CVEA also operates two diesel generating facilities at Glennallen and at Valdez, that are used to supplement generation from Solomon Gulch. The Solomon Gulch Reservoir is glacially fed, and follows a general pattern in filling and drawdown closely related to the timing of glacial melt runoff. Typically, the reservoir is drawn down to a minimum over the winter when there is little if any inflow. Beginning in early May, inflow from snow and glacial melt begins to increase and the reservoir begins to fill The reservoir is usually completely full by mid-July and water spills over the spillway until mid-October. By November 1, inflow is greatly reduced by freezing conditions up on the glacier. The hydroelectric plant cuts back production, but the reservoir level steadily drops until all available storage is used up, usually sometime in late March or early April. The supplemental diesel generation plants must be started up and operated under very uneconomic conditions until runoff begins again in May and the hydro plant can be restarted. 1 The objective of studying the feasibility of raising the spillway by either 2 or 5 feet is to capture a portion of the runoff that currently is spilled from mid-July to mid-October, so lhat the period of operation of the hydro facility may be extended into the spring, hopefully long enough to make full operation of at least one of the diesel facilities unnecessary. I. Alternative Descriptions and Recommended Alternative The existing spillway at Solomon Gulch Reservoir has a crest elevation of 685 feet msl. The rockfill dam and dike have a crest elevation of 690 feet, or 5 feet above the spillway crest. In addition, there is a 5-foot high "wave wall" on the top of the dam and dike with a crest elevation of 695 feet msl. There have been several dam stability analyses done on the Solomon Gulch dam and spillway. These analyses show that the wave wall is stable under flood conditions that have as much as 9 feet of water going over the spillway. For this reason, we have assumed for this preliminary study that it is both feasible and safe to raise the Solomon Gulch Reservoir by up to 5 feet without doing any construction work or adding to the existing dam and dike structures. Any raising of the spillway more than 5 feet, in our opinion, would necessitate using the wave wall as a water retaining structure at all times, which we believe would not be acceptable to FERC. In that case, raising of the rockfill structures would also be required, at a large increase in cost. We have, therefore, limited our review of alternatives to a maximum of 5 feet increase in additional reservoir storage. We have examined several alternative methods for raising the spillway, including: • Rubber dam -2-feet high • Rubber dam -5-feet high • Flashboards -5-feet high • Steel Flap Gates -5-feet high Steel Flap Gates Based on historic costs for steel flap gates, they were immediately rejected for further consideration at Solomon Gulch. Initial costs are from 1.2 to 1.8 times as expensive as the Bridgestone Rubber Dam. Refer to Figure 1. Installation costs are also much greater and considerably more field installation time is necessary with steel flap gates. Finally, steel flap gates invariably reduce the spillway capacity of the existing spillway to some degree since the gate itself takes up room on the spillway crest, even when lowered. This would result in a higher peak reservoir elevation during the design flood, which would result in potential ovenopping of the wave wall. To handle this condition, extensive modifications would have to be employed. 2 10.5 9.5 -:. • • (!! 8.5 li • .. (.) 0 ::: 7.5 CD "i :: 6.5 5.5 4.5 .2 .4 Cost of Crest Gates (F.O.B. Site) .8 1.0 1.2 Cost tn U.S. Dollars x 1,000,000 Figure t Ncces: 1. &eludes Cost ot lnstallaOOn 1.4 2. Each line contains manutacturet's name and numbet,length and type of gate. 3. BIS indicates Bridgestone quote 1.6 1.8 I .• ' ,. , .. Wood Flashboards Installation of 5-foot high wooden flashboards on the spillway was examined. First time installation costs amount to approximately $100,000with subsequent replacements costing approximately $30,(X)() per replacement. There are several drawbacks to a flashboard installation. In this case, when the flashboards failed, the 90 boards (5 feet by 6 feet) would wash down into Solomon Gulch Creek. Some boards could·possibly be recovered at considerable effort from the creek bed, and some will be washed into the bay and lost. This could create some local debris problems in the creek. When the flashboards f~ all the stored water will be lost for the season, since the boards could not be reinstalled until there is no flow over the spillway. H a high flow event occurred between July and October which caused a flashboard failure, the benefit of raising the spillway crest would be lost for that year. Flow records confirm that flood events in this drainage basin are most likely between June and September each year. Flashboards also perform quite poorly under ice conditions. Ice that forms on the reservoir surface can exert pressure on the boards and could make them fail prematurely. In particular, high winds can blow sheet ice against the boards, causing them to fail. Finally, flashboards typically are somewhat erratic when it comes to how and when they fail. Typically, some boards fail with only minimal overtopping, while others stay in place and may never fail throughout a flood event. This makes control of reservoir level during a flood more difficult, and again could result in a higher peak reservoir elevation during the design flood and overtopping of the wave wall. For these reasons, flashboards were rejected as a viable option at Solomon Gulch. Inflatable Weirs or Dams An inflatable dam appears to have all the correct characteristics to make it a good selection for Solomon Gulch. Some of these characteristics include: .1) Can be raised and lowered quickly. 2) Can be raised while flow is passing over it 3) Good performance under ice conditions. 4) Very minor reduction in spillway capacity. 5) Simple and quick to install. 6) Can be partially lowered ~d re-raised if desired. There are several types of inflatable dams, including FabriDam, which is inflated with water, and Sumitomo (Japan), Floecksmuhle Energietechnik GmbH (Germany) and Bridgestone (Japan) rubber dams, which are inflated with air. Fabridams were not reviewed due to the risk of freezing. Based on the review of alternatives, the low pressure air inflatable rubber dam was selected as the alternative for further study. As requested by CVEA, a 2-foot high and a 5-foot high alternative were examined. Of the three remaining companies who supply this type of dam, Bridgestone has the most extensive overall experience, and virtually the only experience of the three in the United 3 ! " States. Sumitomo has extensive experience in Japan and the Far East. Floecksmuhle has very limited experience only in Europe and at this time its product is not being considered further in this study. The Bridgestone product differs from Sumitomo's rubber weir in two substantial ways: (1) Bridgestone's fabric is an EPDM (Ethylene Propylene Diene Monomer) fabric laminated with nylon and is much heavier than Sumitomo's. For a 5.0-foot high rubber dam, the Bridgestone bladder would be 1/2-inch (12.5 mm) thick. Sumitomo's fabric for the same height dam would be less than 3/16-inch (4.1 mm) and made of laminations of synthetic rubber and nylon. (2) Sumitomo does not have an automatic level control system to monitor and maintain a constant upstream water level. Bridgestone has extensive experience with automatic level controls and offer their SCUL system (System for ,Controlling Upstream (water) .Level). Both products have fail-safe methods of deflation. For these reasons, the Bridgestone "Rubber Dam" appears to be a more suitable option for this project. Due to the volume of water and the beneficial ability to control the reservoir water leyel via an automatic control system, the Bridgestone product is considered exclusively henceforth, even though the cost of their rubber dam is slightly higher than Sumitomo's "Sumigate." The inflatable rubber dam system considered here, therefore, is patterned after the Bridgestone Rubber Products "Rubber Dam." The Bridgestone product has been proven to be a durable, dependable system for impounding and releasing water on naturally flowing rivers. The Solomon Gulch Reservoir Rubber Dam System will be comprised of several components, including: two rubber bladders, embedded anchor bolts and clamping plates, inflation/exhaust piping, drain piping. automatically actuated blowers and exhaust valves, control panel, and fail-safe deflation mechanisms. Rubber dams are readily adaptable to different foundation and end pier conditions. Rubber dams are commonly retrofitted onto existing dams as a replacement for flashboards and steel gates. In this case, a small concrete shelf would need to be poured on the upstream face of the existing spillway to form a flat connection surface for the rubber dam. It is not possible to chip a flat area onto the top of the existing spillway since there are post-tensioned rock anchors embedded in the existing spillway with the bolt tops just below the top surface of the dam crest. The foundation of the rubber dam system involves the embedment of steel clamping plates along the foundation slab and end piers. The lower clamping plates are secured to the foundation by anchor bolts designed to withstand the pullout force exerted on the foundation due to lateral hydrostatic forces on the rubber bladder. The rubber bladder is laid over the anchor bolts, and fittings for the air inlet/ exhaust line, pressure sensing line and drain line are secured to the inside of the bladder. A spacer is placed next to the foundation with upper clamping plates and nuts threaded onto the protruding anchor bolts. Air inflation/ deflation, pressure sensing and drain piping for both rubber dams will be connected to a small control building sited on the rockfill dike next to the spillway. 4 , ... Rubber Dam Control Building The control building will be located at the east end' of the non-overflow spillway dike next to the spillway. Three phase 480 volt and 125 volt DC electrical service to the building will be supplied from the valve bouse at the toe of the existing dam. The control building will contain the control panel, control-interface panel, electrical distribution panelboard, lighting panelboard, two 3 phase blowers (one for each rubber dam), two motor-controlled air exhaust valves, two fail-safe bucket actuated air exhaust valves, and the terminus of the rubber bladder drain and pressure sensing pipes (two each).· The two air supply I exhaust systems will be interconnected to allow rubber dam inflation by a non- designated blower while the designated blower is out of service. In addition, an isolation valved connection will be provided on the air supply system to allow inflation of the rubber dams with a portable gasoline powered compressor in case of emergency. The drain piping and all low points in the piping systems will be drained to a sump in the basement of the control building. The drainage will be pumped back to the reservoir through an oil/water separator by a submersible sump pump. The control building will be reinforced concrete slab on grade with an insulated metal superstructure. The building will be approximately 10-feet wide by 25-feet long. The building will be kept heated to approximately 45•F by 5 kW and 3 kW electric beaters. A 12-incb in-line HV AC blower will supply 600 cfm air during periods that the building is occupied by maintenance workers. The building exhaust duct will also serve as air supply and/or air exhaust for the rubber dam blowers. The building air supply and exhaust will be provided by two screened ducts through the roof. Rubber Dam Control System The rubber dam inflation/ deflation system is controlled through the SCUL control panel in the control building. The control center of the rubber dam system is a programmable . . logic controller (PLC). The PLC is programmed to receive input from transducers sensing internal bladder pressure and reservoir water surface elevation. The PLC will actuate the blowers or the exhaust valves to either inflate or deflate the rubber dams. The PLC will be contained in a NEMA Type 4 control panel. The control panel will also contain operating controls, setting switches, status and alarm indication, metering, and regulators for the bl~wers and the electrically-operated exhaust valves. The control system monitors and regulates the internal bladder pressures and automatically inflates and deflates the bladde.~. A pressure transducer is tapped into the pressure sensing air piping from each rubber dam. Internal bladder pressures are continuously monitored and signals relayed to the control cabinet. Upon loss of rubber bladder internal pressure, the blower is actuated to inflate the bladder to its normal operating pressure. Lowering the internal pressure will be accomplished by actuation of the automatic air exhaust valve. The rubber bladders will be controlled to an internal pressure of 3 to 4 psi. Due to the bladders' low internal pressures, each blower is capable of maintaining full inflation pressure in all· but the most catastrophic ruptures. Bullet 5 i' holes are considered non-catastrophic, are almost self sealing, and can be repaired while the bladder remains inflated. The control system also includes a water level transducer for the purpose of providing a constant reservoir water surface elevation. The normal operating water surface elevation ,will be El. 690.0. The PLC will actuate the blowers or the exhaust valves to inflate or deflate the rubber bladders in sequence to maintain this constant reservoir elevation. Upon increasing flow and upon total deflation of the two main span rubber dams, the water surface will increase naturally. In case of loss of power, the rubber dam system is equipped with fail-safe bladder deflation systems at a set point of El. 690.5. The control system will activate gravity feed, water-filled buckets and counter-weighted valve systems to totally deflate the rubber bladders. Under either the normal or fail-safe deflation modes, the rubber dams will deflate at such a rate as to provide a gradually increasing downstream water surface, providing safety for people downstream in or near the spillway channel. This can be accomplished by properly designed deflation pipe sizes. In addition to the normal operations of the SCUL syste~ the control system will include provisions for a communications interface and backup electrical power source, in accordance with CVEA standards. Rubber Dam Operation The rubber dam system will be self controlling and integrated with the powerplant control systems. The SCUL will be programmed to inflate/deflate the rubber dams to control the reservoir water surface at El. 690.0. The SCUL system will control the rubber dams' internal pressure at all times. Each rubber bladder will be operated in series. In the event a loss of electrical power to the SCUL occurs, the rubber dams will retain their prepower-loss states unless the water level rises to the fail-safe set points. If this occurs, both of the main dam's rubber dams will automatically and totally deflate at an overtopping elevation of 690.5 via a gravity feed bucket system so as to preclude damage and overtopping, as discussed above. The rubber dam system is capable of being operated during low temperatures ( -30 ·F) and during heavy ice and debris conditions. It can be operated at any level of inflation/deflation without concern for vibration and damage to the bladder. Expected Maintenance Since the rubber dam system is designed to operate unattended, there is no need for daily service as long as normal operation is observed. The PLC will operate the system and locally annunciate alarms in the event a malfunction occurs. Provisions for remote alarm 6 annunciation and control are possible and may be initiated through the existing plant control system if desired by CVEA The manufacturer claims that rubber dam bladders have an estimated life of over 30 years. The EPDM rubber compound is UV and ozone resistent and not readily susceptible to wear, tearing, or puncture. Leaks are rare, generally caused by exceptional conditions, and are typically not a threat to operation of the system. Normal leaks can be repaired while the bladder is inflated by installing rubber plugs which are supplied with the bladder. No specific maintenance is required for the rubber bladders. There is no exposed metal which requires painting or other maintenance. Anchor bolts and clamping plates are fabricated of stainless steel. Rubber dams are susceptible, however, to damage by firearms or knives. The Weeks Falls Hydroelectric Project, upstream of the Snoqualmie Falls Project on the South Fork Snoqualmie River, Washington State, is a non-remote, unattended installation of a rubber dam in a public par~ which bas not experienced this type of vandalism in 5 years of operation. Puncture by rifle fire is also possible, but, due to the low inflation pressure of the bladder, catastrophic collapse is not likely. Due to the elasticity of the bladder, the bole created by a fired projectile is less than one-third the projectile's diameter. Because of the pressure sensing capability of the control system, the blowers are capable of keeping the bladders inflated to their prescribed internal pressure and assure that the bladders will remain in their upright posture. · Bullet holes have been detected at the Weeks Falls Project, but have only resulted in minor air loss and have hardly been noticeable by cycling of the blower. These boles have been easily patched with no plant downtime and at very low cost. At times of total deflation of the rubber dams, the bladder drain valve should be opened to drain any internal moisture. Most of the moisture inside the bladder is carried by pumping air into the large volume of the rubber bladders. In turn, most moisture exits during deflation. Though rarely required, a check of the drain valves during deflation is recommended. Access to the downstream side of the dam will be possible any time there is not water spilling over the spillway. Upstream access is only possible, for inspection purposes, whenever the reservoir is drawn down. During operation of the dam, it is possible for floating debris to be lodged on the intermediate pier or rubber dam end walls. It is also possible during lower flow events, when the rubber dams are fully inflated, to have debris bang up on the bladders. Such debris may be able to be dislodged and moved downstream by partial deflation of the rubber dam and sluicing tbe debris. Persistent and large debris may require cutting and removal by boat. We are not aware of any debris damage to any rubber dams currently in operation. 7 t" i r· , •. t·· i II. Hydrology and Hydraulics There has been a considerable amount of hydrologic work done on the Solomon Gulch Reservoir, both as part of the original design and as part of the 5-year Dam Safety Inspection. We reviewed the spillway design criteria, reservoir area and rating curves, spillway rating curves and the probable maximum flood event studies performed by both R.W. Retherford Associates and Chas. T. Main, Inc. HDR used this information as the basis for flood and reservoir flood routing calculations. The spillway design flood for Solomon Gulch Reservoir is an event which has a maximum reservoir inflow of 48,300 cubic feet per second (cfs) and a maximum spillway outflow of 37,135 cfs. At this flow rate, there would be 8.5 feet of water passing over the spillway, leaving about 1.5 feet of freeboard to the top of the wave wall. We would want to be sure that any modification to the spillway would not affect its flood carrying capacity and would not raise the maximum flood reservoir elevation, since there is only 1.5 feet of freeboard under the current situation. Since raising the spillway 5 feet is the worst case scenario, we examined the hydraulics of this case first. Please refer to Table 1 and Table 2, the Flood Routing Computations for the current situation and the 5-foot increase case. We assumed that the 5-foot rubber dam was fully inflated and the reservoir was full at the start of a design flood. When there was one-tenth of a foot (0.1 foot) of water spilling over the rubber dam, the dam was lowered. From Table 2, it can be seen that almost all the stored water is spilled out of the reservoir in 3 hours. Inflow from the flood doesn't peak until after 17 hours from the start of the flood. Therefore, the impact of the extra storage is minimal. Comparing the design flood base case to the 5-foot increase case shows that after about 6 hours into the flood event, the impact from the extra 5 feet of storage is difficult to detect. We conclude from this analysis that: 1) Raising the spillway 2 feet or 5 feet will not impact the maximum reservoir surface elevation during a flood if the rubber dam is lowered early in the flood event. 2) The rubber dam control system should be designed to automatically lower the dam in the event of a flood occurring, and should be as fool-proof as possible 3) Any time the rubber dam is inflated and the reservoir is full, completely lowering the rubber dam will result in a flow of about 19,000 cfs down the spillway creek for a brief period, dropping down to about 10,200 cfs after the first hour. A flood of this magnitude is still only about balf of the design flood, but is expected to have some downstream impact. III. Energy Production Raising of the spillway crest will increase energy production at Solomon Gulch by three ways: 8 r' · · .Solomon Gulch Reservoir -E.xlatlng Conditione FLOOD ROUTING COMPUTATIONS Average I •,.,.... Average Average In ere- Rate Inflow Average Rate Out-Flow mental Total Reservoir Time for ll t Inflow Out-now for ll t Storage Storage Elevation Hours ... Sec:ond-Ft Ac:re-Ft Sec:ond-Ft Ac:re-Ft Ac:re-Ft Ac:re-Ft End ll t 0 31500 685 1.31 500 55 47 6 + 49 31549 685.1 2.31 700 58 134 11 + 47 '31596 685.2 3.31 2100 175 530 44 +131 31727 685.5 4.31 8000 667 2753 229 +437 32164 686.5 5.31 10900 908 5923 494 +415 32579 687.5 6.31 11700 975 7786 649 +326 32905 688.0 7.31 12000 1000 9812 818 +182 33087 688.5 8.31 12300 1025 9812 818 +207 33294 688.5 9.31 15200 1267 11988 999 +268 33562 689.0 10.31 17100 1425 14305 1192 +233 33795 689.5 11.31 18200 1517 16754 1396 +121 33916 690.0 12.31 19800 1650 16754 1396 +254 34170 690.0 13.31 20600 1717 19329 1611 +106 34276 690.5 14.31 22800 1900 22023 1835 + 65 34341 691.0 15.31 29000 2417 24833 2069 +347 34688 691.5 .16.~1 40100 3342 27753 2313 . +102.9 35697 692.0 17.31 48300 4025 37135 3095 +930 36625 693.5 18.31 34000 2833 37135 3095 -261 36364 693.5 19.31 15300 1275 27753 2313 -1038 35326 692.0 20.31 8300. 692 19329 1611 -919 34407 690.5 21.31 . 6800 567 14305 1192 -625 33782 689.5 22.31 6200 517 9812 818 -301 33481 688.5 23.31 5700 475 7786 649 ' -174 33307 688.0 24.31 4500 375 7786 649 -274 33033 688.0 Baae Caae 1991 Table 1 From FERC License +2742 Exhibit K Drawing No. H01-F•04-2011-R49 rev. 3 dated 1-3-83 I, . TABLE 2 FLOOD ROUTING -SOLOMON GULCH RESERVOIR WITH NEW FIVE-FOOT RUBBER DAM 0 I 1.31 I 0 I I 685.0 I I I I I 34,170 690.0 Start Flood . 1.31 I 1.31 I soo I 55 685.1 47 5 49 34,219 690.1 Drop Rubber Dam I I 1.31 I 700 58 688.6 10,200 14,764 1,220 -1,162 33,056 I 688.5 I 2.31 3.31 I 1.31 I 2,100 175 687.4 5,571 7,885 652 -477 32,580 I 687.5 4.31 I 1.31 I 8,000 667 687.7 6,648 6,110 50S 162 32,742 I 687.7 5.31 I 1.31 I 10,900 908 688.3 8,983 7,816 646 262 33,004 I 688.3 6.31 I 1.31 I 11,700 975 688.5 9,812 9,397 777 198 33,202 I 688.5 7.31 I 1.31 12,000 1,000 688.6 9,812 9,812 811 189 33,391 I 688.6 8.31 I 1.31 12,300 1,025 688.9 11,541 10,676 882 143 33,534 I 688.9 9.31 I 1.31 I 15,200 1,267 689.6 14,797 13,169 1,088 178.6 33,713 I 689.5 10.31 1.31 17,100 1,425 690.0 16,753 15,775 1,304 121 33,833 I 689.9 11.31 1.31 18,200 1,517 690.0 16,753 16,753 1,385 132 33,965 I 690.0 12.31 I 1.31 I 19,800 1,650 690.0 16,753 16,753 1,365 265 34,230 I 690.3 13.31 I 1.31 I 20,600 1,717 690.8 20,950 18,851 1,558 159 34,389 I 690.9 14.31 1.31 22,800 1,900 691.5 24,833 22,891 1,892 8 34,397 I 691.1 15.31 1.31 29,000 2,417 691.5 24,833 24,833 2,052 364 34,761 I 691.5 16.31 Flood routing after hour 15.31 matches flood routing base case without new rubber dam. 1) Increased storage in the reservoir after the inflow stops in November each year. 2) Higher average head in the reservoir by either 2 feet (0.3%) or 5 feet (0.77%). 3) Increased capture and less spill of inflow during July through October Increases caused by 1 or 2 above can be estimated directly with good accuracy. Increases due to 3 above are highly variable and difficult to estimate. In some cases, lack of sufficient load on the system would prevent these gains from being realized. Therefore, increased generation for reason three has not been estimated in this study. At 645 feet of effective head, for example, one turbine at nearly full load of 5,010 kW uses 108 cubic feet per second of water. This means the unit can run about 0.11 hours on one acre-foot of water (43,560 cu. ft) and produce about 561 kWh of energy. From the turbine efficiency curves, it can be seen that this output of 561 kWh/acre-foot will remain fairly constant with either a 5-foot or a 2-foot head increase. Raising the spillway will also result in a higher average head throughout the operating year of a small percentage. This will increase annual production accordingly. The following table shows the projected energy increases for spillway elevation increases of both 2 feet and 5 feet 2 Feet 1,000 ac-ft 561,000 kWh 120,000 kWh 681,000 kWh 5 Feet 2,500 ac-ft 1,402,000 kWh 300,000 kWh 1,702,000 kWh IV. Cost Estimate The cost estimate to install either a 2 foot or a 5 foot Bridgestone Rubber Dam on the Solomon Gulch spillway was prepared by obtaining a firm quotation from Bridgestone for . . the dams and by estimating unit quantities of concrete, rebar, anchor bolts, electrical wiring, etc. The estimates are shown on the following four pages. Cost estimates for FERC licensing are prepared with two separate options, a minor amendment or a major amendment. Reasons for this approach are explained in the section on FERC licensing below. Delivery of the rubber dam is normally 5 months from p~~cement of order. Construction time in the field should be completed in about 3 months, one month of preparation prior to dam delivery and 2 months for complete installation. The total estimated cost for the 2-foot increase project is $723,148. The estimated cost for the 5-foot increase project is $1,547,548. Both estimates contain contingency, 20 percent for construction costs and 40 percen~. for licensing and permit costs. If further confirming feasibility studies are conducted, these contingencies should be able to be reduced.· 9 ITEM 1 2 3 4 s 6 7 8 9 10 11 12 13 14 15 16 COPPER VALLEY ELECTRIC ASSOCIATION SOLOMON GULCH RESERVOIR HEIGIIT INCREASE DET AD..ED COST ..ESTIMATE (January 1992 Dollars) TWO FOOT INCREASE CASE DESCRIPTION Mobilization Rubber Dam Including Controls (2-Two Foot Dia. X 225') Control House Building Electrical : 480V Service To Control House Control House Internal Wiring Dam Installation: Remove Splitter Piers Concrete for Dam support (form & pour) Drill in Rebar Set Anchors Form and Pour new center pier Install Rubber dams Bridgestone Site Rep. Start-up and Test Design Engineering Construction Management SUBTOTAL CONSTRUCTION Contingency TOTAL-CONSTRUCTION ONLY Page 1 of 4 Quantity Unit 1 Is 1 ea 250 sq ft 1260 ft 1 Is 17 ea 25 cuyd 1 Is 1 Is 5 cuyd 2 ea 40 days 1 Is 1 Is Is 20% Unit$ Cost$ $10,000 . $10,000 $273,000 $273,000 $75 $18,750 > ...... ) .............. ; ··•. $4 $5~040 $6,000 .$6,000 : .. .........•••.•.•.•..••......•.•..•••......... : $500 . )$8,500 $1,000 . •$25.0()() $3,000 > .$3;~ $2,000 . $2,000. $1,000 (· $5~000 $8,000 ; >}.$1~.{)()() $600 <'$24;000. $55,000 $55,0()() $25,000 $25~00() >:-_-· :>: <:>::::::-:: __ : :·:·==:~:. $481,29(). ·-~ :-:::.>(:··· :::;:-:.::::-__ :_·_::?:: . $96,258. ~~tm!iB.ri FERC Licensing: (Assumes Minor Amendment) 17 Prepare Draft Licensing Plan & Proj. De 1 Is $15,000 $15,000 18 Agency Consultation 1 ls $12,000 <$12,000 19 Draft Amendment Application 1 Is $5,000 $5,000 '""' 20 Agency Review and Comment 1 ls $10,000 $10,000 21 FERC Filing and Follow-up 1 ls $5,000 $5,000 22 Contingency 30% >$14,100 Subtotal FERC Licensing . $61,100 FERC Licensing: (Assumes Major Amendment) 17A Prepare Draft Licensing Plan & Proj. De 1 Is $20,000 18A Agency Consultation 1 ls $15,000 19A Conduct Public Hearing(s) 1 Is $5,000 20A Perform Required Studies 1 Is $30,000 21A Draft Amendment Application 1 Is $10,000 22A Agency Review and Comment 1 Is $12,000 23 FERC Filing and Follow-up 1 Is $12,000 24 Contingency 40% Subtotal FERC Licensing 25 TOTAL COST (Minor Amendment) 26 TOTAL COST (Major Amendment) Note: Estimated licensing costs are based on the assumption that CVEA staff will provide significant support for required field work and studies, including labor, small tools and transportation 2 of4 ITEM 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 COPPER VALLEY ELECTRIC ASSOCIATION SOLOMON GULCH RESERVOIR HEIGHT INCREASE DETAILED COST ESTIMATE (Janwuy 1992 Dollars) FIVE FOOT INCREASE CASE DESCRIPTION Quantity Unit Mobilization 1 ls Unit$ Cost$ $10,000 •$10,000 .~ . Rubber Dam Including Controls (2-Five Foot Dia. X 225') 1 ea $471 ,ooo <$tn,Oo6 Control House Building Electrical : 480V Service To Control House Control House Internal Wiring Dam Installation: Remove Splitter Piers Concrete for Dam support (form & pour) Drill in Rebar Set Anchors Form and Pour new center pier Install Rubber dams Bridgestone Site Rep. Start-up and Test Design Engineering Construction Management SUBTOTAL CONSTRUCTION TOTAL-CONSTRUCTION ONLY Page 3 of 4 250 sq ft 1260 ft 1 Is 17 ea 502 cuyd 1 Is 1 Is 5 cuyd 2 ea 45 days 1 Is 1 Is 1 Is 20% ::::_:·-=:~:+:;=-=.::.:::=::>< ··········\·················i .....•....... $15 ::$18~750 ···• in i••••••<•• $4 <",;\"i~;~ $6,000 .· . $ti,OOO .·-.-·-·· ,,., .. _ .. ::-_: :::~ ::: C::: ::-:::-::-=:::_ :::.::X-::·=:~ ~i $500 rr~1~~~rm:! $1,000 $502~000 $3,000 .····••·· $3,000 $2,000 > $2~000 $1,000 ·. $5,000 $10,000 :: $2(),()()0 $600 •.... $27,000 -::-:::):/>?F>:\/:::_=:. $5,000 $5,000 ~ ;= ): ) . :~~;~ :' _; -~ ~-;: :-:.:·:=':: ~;=;=~:;·;. ;_ ;: $60,000 $60,()00 $25,000 $25,ooh st,i~&.i~ . .. $233,658 .. ili~~~iJ,iM 17 18 19 20 21 22 17A 18A 19A 20A 21A 22A 23 24 25 26 FERC Licensing: (Assumes Minor Amendment) Prepare Draft Licensing Plan & Proj. De Agency Consultation Draft Amendment Application Agency Review and Comment FERC Filing and Follow-up Contingency Subtotal FERC Licensing FERC Licensing: (Assumes Major Amendment) Prepare Draft Licensing Plan & Proj. De Agency Consultation Conduct Public Hearing(s) Perform Required Studies Draft Amendment Application Agency Review and Comment FERC Filing and Follow-up Contingency Subtotal FERC Licensing TOTAL COST (Minor Amendment) TOTAL COST (Major Amendment) 1 1 1 1 1 1 1 1 1 1 1 1 Is Is Is Is Is Is Is Is Is Is Is Is $15,000 $15,000 $12,000 $12,000. $5,000 .ss.ooo $10,000 $10,000 $5,000 $5,000 30% $14;100 $61,100 ··. . . -.... :--_::>:}::.:::::·:::::: $20,000 . · .. $20,000 $15,000 ·.. $15;000 . ss,ooo .· 'sS,oocl $30,000 ; ; $30,000 $10,000 $lO,o00 $12,000 . ·.·. $1~~000 $12,000 $12,000 ,' -__ :: ·_ :_-:/::>·_::\:)_\~>.V 40% s4i~6o0 <$145,600 !!111ll1% 1;14.1~11!\: Note: Estimated licensing costs are based on the assumption that CVEA staff will provide significant support for required field work and studies, including labor, small tools and transportation Page 4 of4 V. Economic Analysis Following is a simple comparison of the study results for the 2 foot and 5 foot options: 5-Foot Increase $1,547,548. 1,702,000 0.91 2-Foot Increase $723,148. 681,000 1.06 This simple comparison shows the 5-foot increase project is considerably more cost effective than the 2-foot increase project. Further analysis will only address the 5-foot increase project. For this study, it was not possible to perform a detailed economic analysis of the project mainly due to uncertainty about financing methods, sources and costs of funding and potential savings. However, the chart below illustrates some potential economics based on some simple assumptions: The savings shown above are only assumptions and do not consider potential savings from operator costs at the hydroelectric project or other potential savings at the diesel generating plants. VI. Environmental Concerns and Other Issues H a project was undertaken to raise the spillway at Solomon Gulch, we would expect a variety of environmental concerns to be raised by local, State and federal agencies with jurisdiction over the project. We have reviewed the existing FERC License for the project as well as the original FERC License Application and the original project environmental impact statement. Following is a list of questions, concerns and issues that we believe will be raised as part of the permit process for raising the spillway: 10 SHORT-TERM IMPACIS A) Disturbance to Wildlife Will construction-related noise, human presence and activity cause significant impacts to wildlife? ("Significant" in this context usually means a permanent or long-term loss in local population level). Note: According to the Final EIS for the original project, "several wildlife species inhabiting the proposed project area are considered endangered, but maintain stable populations within Alaska. They include the wolf and brown/grizzly bear." -FERC, Final EIS, 1978, Page 2-20. No rare, threatened or endangered plants are known to exist in the project area. -FERC, Final EIS, 1978, Page 2-20. "There are no wetlands or other known areas of critical environmental concern connected with the proposed action of the Solomon Gulch Project." - Application for License, Exhibit W, Page 38, R. Retherford Associates, 1975. B) Construction Timing How will the timing of construction activities affect fish and wildlife? Note: For the original project, the ADFG requested that blasting activities be scheduled for mid-summer to fall, when big game populations are generally dispersed to higher elevations. -FERC License Application, Exhibit S, 1976. C) Water Quality Impacts 1) What will be the effects of increased turbidity, suspended solids, construction materials, and other pollutants in the lake or creek? 2) Will there be any alteration to the downstream flow regime during construction which will affect water quality parameters such as temperature and dissolved oxygen, or minimum flows? 3) What will be the impacts to existing fiSh and fisheries habitat from construction activities? Note: Native salmon spawning in Solomon Gulch Creek appears to be very limited. ADFG found that only 200-500 pink and chum salmon used the creek for spawning and only in the intertidal area in odd-years. -FERC License Application, Exhibit S, 1976. ADFG also found no resident ·fish population in Solomon Lake. -FERC License Application, Exhibit S, 1976. 11 ,- I· 4) What will be the impacts to Water Quality and Fisheries from leachate from abandoned mines? D) Air Quality Impacts What will the be the effects of increased dust and hydrocarbon emissions to local air quality? E) Erosion and Sedimentation What will be the effects of erosion and sediment on vegetation, wildlife habitat, water quality, and fisheries? LONG-TERM OPERATIONAL IMPACfS A) Wildlife 1) Will the higher lake level block any wildlife passage or inundate any unique habitat? 2) Will project features (dam) result in the loss of wildlife habitat? B) Fisheries 1) Will draw down of lake under the new lake level conditions cause water quality impacts, such as changes to temperature or dissolved oxygen in discharge waters? 2) What will be the effect of increased· discharge water to downstream fish populations and habitat? 3) What will be the effect of increased discharge water to the downstream fish hatchery operation? (Increased winter flows are expected to improve hatchery operations). C) Recreation 1) Will the higher lake level inundate existing or proposed recreation facilities? 2) What will be the increased visual impacts, if any, of the larger new dam? 3) What will be the effect of the project on recreational demand in the area? Will public access be improved or new demand created? 12 Raising the reservoir level on an impoundment will automatically trigger the need for a FERC Ucense Amendment. There are basically two types of amendments, a minor amendment and a major amendment. The minor amendment is used when there are no significant environmental impacts expected from a change and no objection by any agencies or the public. FERC will deem the change to be a "non-significant action" on the part of FERC, give public notice of the change, and in the Federal Register asking for comments after the notice period if there are no intervenors, FERC will issue the amendment. This process normally can take 6 months and as little as 3 months from date of application. A major amendment is used if there is any chance of significant environmental issues surfacing or any controversy over the proposed change. It is also used any time FERC must say the change is a "significant action". If there is any Agency opposition to the change it will likely require a major amendment The major amendment process includes the ECPA three stage consultation process, preparation of draft license amendments, study plans, three stages of agency consultation and public hearings. It is difficult to process a major amendment in less than 1-1/2 to 2 years due to statutory notice and waiting periods for agency review and comment FERC staff indicated in the informal conversation that this project .muJJ;l be a candidate for a minor amendment based upon our explanation of the proposed improvement. We would need to prepare a complete project description and solicit Agency comments. If we get support from all the local agencies and can settle all potential issues to everyone's satisfaction before we officially apply to the FERC, they may well treat the application as a minor amendment. If, however, any agency requests the full three stage consultation process, FERC will have no option but to treat the project as a major change, which would demand the major amendment process. This uncertainty makes it difficult to assess this aspect of the overall project. Unfortunately, further study will not eliminate this uncertainty. Initial agency contactS will give us some indication of local concerns and agency positions, but some uncertainty will still exist on this issue up until FERC accepts the application and confirms it as either a minor or major change. Our cost estimates used for economic analysis in this report assumed a major amendment would be necessary. · IX. Conclusions and Recommendations It is concluded that: 1) Both the 2-foot increase and the 5-foot increase projects are feasible technically. 2) Increase beyond 5 feet will require dam structure modification and will be very costly. With proper controls, the 5-foot increase will not affect the flood routing of the probable maximum flood through Solomon Gulch Reservoir. 14 i- I~ 3) The 5-foot spillway height increase is more attractive than the 2-foot increase. 4) The 5-foot increase project is estimated to cost $1,547,500. Additional annual generation of 1,702,000 kWh is projected as a result of this change. It is recommended that: 1) CVEA examine the potential system wide savings from this potential project and compare the costs we have ·projected to the potential benefits. Our simplified analysis indicates that savings in excess of nine cents per kilowatt hour will need to be realized just to make the debt service payments for the project. 2) CVEA should make a GO/NO GO decision on this project. If a GO decision is made, HDR will proceed with a more detailed and in depth analysis of the project, including a more in depth environmental review, informational contacts with fish hatchery and key agencies, refinement of design and cost estimates and preparation of preliminary design layouts and drawings. Other issues that need to be reviewed should the project proceed include: * * * * Review downstream facilities for flood impacts due to lowering the rubber dam, especially the fish hatchery. Review bridge abutments on access road to check impact of flood from lowering dam. Verify turbines and penstocks capability to handle higher pressure. Investigate benefits to fish hatchery from additional availability of water. HDR is available to assist CVEA in whatever ways possible in making the GO/NO GO decision. 15 APPENDICES 1. Bridgestone Cost Quotations • Rubber Dam 2. Connection Diagram • 2-foot Dam 3. Connection Diagram -5-foot Dam 4. Letter from Bridgestone regarding ice performance ! . r October 10, 1991 Mr. Jack Snyder HDR Suite 200, Building C 11225 S.E. Sixth Street Bellevue, WA 98004-6441 RE: YB call of October 1 0: Solomon Gulch Rubber Qam Dear Mr. Snyder, ~R/06ESTORE BRIDGESTONE ENGINEERED PRODUCTS COMPANY 7659 775 Avenue West Oak Harbor, WA 98277 A Division of Bridgestone/Firestone, Inc. TEL: (206) 679·1249 FAX: (206) 675-6558 Thank you for your call today concerning the Solomon Gulch Project. Enclosed please find the following: 1) Price quotes for 2'H x 235'L x 2 span Rubber Dam and 5'H x 235'L x 2 span Rubber Dam 2) Copy of simplified cross section of Solomon Gulch Spillway. Based on this sketch our engineering staff will make drawings showing how 2' and 5' high Rubber Dams might be attached to the existing structure. These drawings should be completed in about two weeks. 3) Copy of letter sent to Mr. Mike Easley of Copper Valley Electric. 4) Bridgestone Rubber Dam sales and technical information consisting of White Folder and Grey Binder. The ability for the Rubber Dam to greatly increase the utility of the reservoir seems, at first glance, to make this project cost-effective. Determining that is your job. Mine is to provide all the information necessary to aid your evaluation of the Bridgestone Rubber Dam option. I look forward to working with you. Very truly yours, CK~~~ St~;;aGrave Bridgestone En ineered Products Company CC: BEP-N 5230C I ~· BRIDGESTONE RU8BER OAM PRICE ESTIMATE Project: Solomon Gulch Date: October 10, 1991 SPEC/FICA TIONS Height: 2 feet Length: 235 feet (on foundation) Side Slope: 1 : .5 (V:H) Anchor: Single Anchor Une Cost Per Span: US $129,050 Number of Spans: 2 Optional Control SYS Cost: US $25,000 Quote Offer. US $283,099 PRICE PRICE CONDITIONS Price Condition: FOB job site. Delivery Terms: To job site within fiVe months of purchase order and drawing approval. Packing: Bridgestone standard (wooden case/roll), normally containerized. Payment: Net 90 days. Validity: Until January 8, 1992 Standard Equipment: Rubber Darn Body; Embedded Plates; ClaJ'll)ing Plates; Anchor Botts; Spacer Pipes; Air Blower; Control Panel; Automatic Deflation Mechanism; Design Documents, Drawings and Manuals. FIXing Components: Clamping Plate: Galvanized ductile cast iron JIS FCDSOIASTM A536 GR.60 Embedded Plate: Galvanized rolled steel JIS SS41/ASTM A36 Anchor Bolt: Galvanized chrome molybdenum steel JIS SCtM35fASTM A29 GR.4235 Nut: Galvanized carbon steel JIS S45C/ASTM A575 GR.1045 Control System: 5 Inner pressure of Rubber Dam is controlled in pre-set range by automatic air supply/exhaust function. Automatic Deflation System: Bucket Type Excluded From Price: Concrete and Civil Works, .Installation Cost, Site Advisor for installation of Rubber Darn. (Per October 11l/91 request of Mr. Jack Snyder of HDR. · ory Manager red Products Company J BBIDGESTOHE RUBBER DAM PRICE ESTIMATE Project: Solomon Gulch Date: October 10, 1991 SPEC/FICA TIONS Height: 5 feet Length: 235 feet (on foundation) Side Slope: 1 : .5 (V:H) Anchor: Single Anchor Une Cost Per Span: US $232,782 Number of Spans: 2 Optional Control SYS Cost: US $25,000 Quote Offer: US $490,563 PRICE PRICE CONDITIONS Price Condition: FOB job site. Delivery Terms: To job site within fiVe months of purchase order and drawing approval. Packing: Bridgestone standard (wooden case/roll). normally containerized. Payment: Net 90 days. Validity: Until January 8, 1992 INCLUDED IN PRICE Standard Equipment: Rubber Dam Body; Embedded Plates; Clamping Plates; Anchor Bolts; Spacer Pipes; Air Blower; Control Panel; Automatic Deflation Mechanism; Design Documents, Drawings and Manuals. FIXing Components: Clamping Plate: Galvanized ductile cast iron JIS FCD501ASTM A536 GR.60 Embedded Plate: Galvanized rolled steel JIS SS41/ASTM A36 Anchor Bolt: Galvanized chrome molybdenum steel JIS SCM435JASTM A29 GR.4235 Nut: Galvanized carbon steel JIS S45C/ASTM A575 GR.1045 Control System: [ 5 ] Inner pressure of Rubber Dam is controlled in pre-set range by automatic air supply/exhaust function. Automatic Deflation System: Bucket Type Excluded From Price: Concrete and Civil Works. Installation Cost, Site Advisor for installation of Rubber Dam. (Per October 10/91 request of Mr. Jack Snyder of HOR. rritory Manager red Products Company COMMENTS ] I, ,_ ,. Solomon Gulcti Rubber Dam 2.' ---ll:..-------· _ ..... AfP/ZIJX I f.t- 2 Foot Case Rubber Dam Rubber Dam ' / t\J / ~ ' / ~ "' 1> ... ... / ... ~ ' " ~ ./ .. s;. I -1:::. t\=T\'\OJ) .. ~" 'Wi:il:>"G 'Sil.fiVE \ I \ /-It" ' \ .. t \ \ \ I \ I' ~~ I M~'O ~ < ~C.j.\'0 wf'.\..i.. "CO ~ ::> ::0 ;r;, I ,., -,, '"' Solomon Gulch Rubber Dam 5 Foot Case October 10 1991 Mr. Mike Easley Copper Valley Electric P.O. Box45 Glenn Allen, Alaska 99588 Dear Mr. Easley, .Jti/U6ESTOI/E BRIDGESTONE ENGINEERED PRODUCTS COMPANY 7659 775 Avenue West Oak Harbor, WA 98277 A Division of Bridgestone/Firestone, Inc. TEL: (206) 679·1249 FAX: (206) 675-6558 Pursuant to your call of September 30 and my fax of October 1 please find enclosed photographs of our Palmer Falls Rubber Dam undergoing ice over- topping. Although I know you already have our literature, I have enclosed another set as well. I would like to advise you that today I received a telephone call from Mr. Jack Snyder of HDR who advised that his firm had been engaged by Cooper Valley Electric for the Solomon Gulch Project. I advised him that it may be helpful at this stage to have· detailed drawings showing attachment of the Rubber Dam on the crest of the spillway and that we can proceed with such if provided a cross section of the existing spillway. Mr. Snyder said he would fax same. I hope to forward such drawings to him in two weeks. I look forward to the privilege of working with you. Very truly yours, ineered Products Company cc: HDR Mr. Jack Snyder BEP~N I . .. PALMER FALLS RUBBER DAM ALTHOUGH THIS ICE IS THIN, 3 FEET IS COMMON AT THIS SITE SEE ATTACHED SUPPLY EXAMPLE FOR PICTURES OF THIS RUBBER DAM WITHOUT ICE I. I PALMER FALLS RUBBER DAM ALTHOUGH THIS ICE IS THIN, 3 FEET IS COMMON AT THIS SITE SEE ATTACHED SUPPLY EXAMPLE FOR PICTURES OF THIS RUBBER DAM WITHOUT ICE PALMER FALLS RUBBER DAM ALTHOUGH THIS ICE IS THIN, 3 FEET IS COMMON AT THIS SITE SEE ATTACHED SUPPLY EXAMPLE FOR PICTURES OF THIS RUBBER DAM WITHOUT ICE ! --- PALMER FALLS RUBBER DAM ALTHOUGH THIS ICE IS THIN, 3 FEET IS COMMON AT THIS SITE SEE ATIACHED SUPPLY EXAMPLE FOR PICTURES OF THIS RUBBER DAM WITHOUT ICE .JRID6ESTORE HYDROELECTRICITY HUDSON RIVER U.S.A. Rubber Dam atop rehabilitated Dam. Powerhouse is on the left . . . Flashboards were replaced with two Rubber Dam spans.