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HomeMy WebLinkAboutAngoon Hydro Study 1989ANG 012 Alaska Energy Authority LIBRARY COpy - ANGOON HYDRO STUDY PREPARED FOR ALASKA ENERGY AUTHORITY AUGUST 1989 polarconsult alaska, inc. ENGINEERS. SURVEYORS. ENERGY CONSULTANTS 1503 WEST 33RD AVE.-ANCHORAGE, ALASKA 99503 • ... ... • '" 411 "" "', ., '" ... , ,," ., ... . , ., 111' .. , ., ., .. , ., .. , ., polarconsult Angoon Hydro Study TABLE OF CONTENTS I. INTRODUCTION ........................................ 1 II. PREVIOUS STUDIES ................................... 1 I I I. COMMUNITY ENERGY PROFILE ........ ' ................... 3 IV. RECONNAISSANCE ..................................... 4 V. PLAN ............................................... 4 A. Assumptions ..................................... 4 B. Diversion ....................................... 5 1. Layout ...................................... 6 2. Construction ................................ 7 3. Intake ...................................... 8 4. Pipeline .................................... 8 5. Powerhouse .................................. 9 6. Transmission ............................... .11 7. Trail ...................................... 11 8. Potential .................................. 12 C. Tunnel ........................................ .13 1. Layout ..................................... 13 2. Intake ..................................... 14 3. Diversion weir .............................. 14 4. Tunnel ..................................... 14 5 . Pipeline .................................. 15 6. Powerhouse ................................. 15 7. Transmission ............................... .16 8. General Discussion .......................... 16 VI. ESTIMATE ......................................... 17 VII. CONCLUSIONS ...................................... 20 VIII. RECOMMENDATIONS ................................. 23 APPENDIX Location Map Thayer Lake, Plan (2 Sheets) Pipeline Route Profile Photographs, Diversion Tunnel Site Plan Typical Pump Turbine Thayer Creek Flow Duration Curve , I ( Olz.. .. .. .. .. ... ... III III .. .. .. ' <II, "', '.' .. , . , ., ,"" .a' polarconsult Angoon Hydro Study I. INTRODUCTION Alaska Energy Authority commissioned Polarconsult Alaska, Inc . to investigate previous reports, review alternatives, make a field reconnaissance and get community input, develop cost estimates, and make a report on hydropower potential for the communi ty of Angoon. The report as follows represents the culmination of these tasks. II. PREVIOUS STUDIES There have been previous studies and reviews of the potential to provide service to this community. What makes this study different is that it considers an entirely new project site and new technology. It also optimizes to the extent possible local labor and participation . The previous studies which are listed, analyzed placing a dam near the mouth of Thayer Creek, constructing a combined power, water supply, and fish hatchery at Favorite Bay, and a tidal power generation system adjacent to the community. In addition to these studies, several economic analyses were made in 1984. The last conclusion of these analyses was that the previous hydro projects were not economically feasible. These conclusions were largely based on the great capital cost of the al ternati ves and the small size of the resource to make the pay back. To place the situation in perspective the cost for the Thayer Creek Project was estimated as $9,400,000 in 1987 dollars. The capital cost for Favorite Bay exceeded $10,000,000 in 1984 dollars . The reports and studies reviewed and analyzed are as follows: 1 .. .. .. '. -.. .. .. .. - ... ... ' .' .. , '., ., 4111 "'Ii ., ~ • • .- ... .. polarconsult Angoon Hydro Study Title 1. Thayer Creek Project 2. Angoon Tidal Power & Comparative Analysis 3. Angoon Hatchery Concept 4. Angoon Water Supply Alts 5. Angoon Hatchery, Final PNP Permit Application For APA* Div of Energy Angoon Aquaculture Association APA* Angoon Aquaculture Association 6. A Comparative Economic APA* analysis of Electric Energy Alternatives for Angoon, Alaska 7. Findings & Recommendations Angoon Hydropower APA** * Alaska Power Authority now Alaska Energy Authority ** Internally generated analysis by the Authority . Date Oct 1979 Feb 1981 Sep 1980 Aug 1981 Feb 1982 Feb 1984 Dec 1984 2 .. .. ... .. .. • .. .. - ... ' . .. .. ... .. .. • .. .. -----------,-,--------_._------------_._-, -" ---------------- polarconsult Angoon Hydro Study III. COMMUNITY ENERGY PROFILE Angoon is a community of 639 people which is located on Admiralty Island near Juneau. AngoQn has 134 residential meters, 22 commercial meters and 7 community meters according to the "First Annual Statistical Report of Power Cost Equalization Program" published by the Authority . Alaska Energy Angoon obtains its power from a central diesel electric power plant. This plant has a installed capacity of about 950 Kw, and has a typical winter demand of 450 Kw and a summer demand of 240 Kw. The peak has reached 500 Kw on a 15 minute demand according to personal communications with Mr. Walter Soboleff. Earlier utility reports gave the demand as 0.3 Mw. For FY 1988 the total Kwh sold are 1.470 million, the fuel consumed was 144,000 gallons, at a cost of $105,000, and the operating disbursements from the State were $227,349. The Kwh sold per gallon was 10.2, the operating cost per Kwh was 13.4 cents and the average PCE was 21.8 cents. This diesel plant is equipped with a waste heat facility which provides heat to community buildings. 3 .. '" .. .. ... .. .. .. .- "- .. .. .. .. .. ... • .. .. • polarconsult Angoon Hydro Study IV. RECONNAISSANCE Two members from Polarconsul t went to Angoon in July. During the visit the diversion scheme was surveyed, the dam and tunnel site at Thayer Creek was observed, and the electrical transmission line route was flown. Tpe results of the teams observations were presented to Richard George, Sterling Bolima, and Albert Kookesh. Unfortunately, Mr. Soboleff was called away unexpectedly for a funeral. Discussions were also conducted as to the communities capability and desires as to a project of this type . V. PLAN Two sites were explored and analyzed. The first one was a potential diversion site which brings water directly from Thayer Lake over a divide to a stream which runs into Mitchell Bay. Alaska Energy Authority, AEA, selected this as the primary site to be investigated. The other site to be investigated was a dam site at the mouth of Thayer Creek that was studied by Harza. (See Ref.i) The task was to determine if there was a way to make this project less expensive. A. Assumptions The basis for this study was to analyze a hydro plant sized to meet the communities needs, which is about 600 Kw. This sized plant should have the minimum capital and operational cost. It was also assumed that maximizing the use of local labor was desirable. The system should be designed so that it would have the minimum of environmental impact because some of the potential project is in a wilderness area and because Alaska Energy Authority, Polarconsult and the potential client find this desirable. Further, it is helpful to increase sources of employment and income for the local people and so it is desirable to enhance local renewable resources. Therefore, 4 .. .. .. • .. .. .. .. ... .. .. .. • ,.., polarconsult Angoon Hydro Study project criteria also included provision for a hatchery and the potential for future mariculture. Flow duration data and a Reference 1 cited previously. calculated, Exhibit T-5, of report's appendix. The flow geologic report was taken The flow duration curve that the Reference is shown in duration curve shows that from was this the minimum flow at 100 percent exceedence is 65 cfs. Polarconsult selected for the study, an operational flow 50 cfs, which is conservative, based on the figures. At this flow sufficient water should remain for the pink' salmon run which stops below the falls on Thayer Creek. Since the average annual flow of this creek is estimated at 405 cfs and the minimum monthly average is estimated as 150 cfs, and Thayer Lake has a surface area of 2787 acres, one foot of surcharge on the lake stores about 1393 cfs days. Or for a period of 30 days, a typical dry period, about 40 cfs could be produced with a draw down of one foot. During the site visit the lake shore showed that the water surface was about 1 1/2 feet below its normal level. This summer had a long very hot dry period and the water level in the creek was low. B. Diversion The diversion system layout is shown in the drawings in the appendix along with a profile of the ground. The critical area of the profile which is the first 3000+ feet was measured utilizing inclinometers and a string transit. Using the lake elevation as 370 feet, the elevation of the highest point was 417 feet which is 47 feet above the lake elevation. The balance of the profile was obtained from USGS quad maps and augmented utilizing photo pairs. The diversion route lies in a old channel which was cut by a very large stream which indicates that at one time this location was an outlet of Thayer Lake or of the glacier which was in its place . 5 .. -.. .. .. .. .. ... ' .. ' .. .. .. ... OR • • • • ... • .. .. polarconsult Angoon Hydro Study The diversion system pipeline profile starts from a small lake which is connected to Thayer Lake but is currently dammed by beavers. This pond, which is 40 acres in extent, is to become the intake for the project. The beaver dam will need to be removed and perhaps the channel between the two lakes deepened. At the time of the field trip sufficient water would not have flowed between the two lakes. Excavation between the lakes can be easily done with a few days of hand labor . There is a boat lift boom at the beaver dam and a local family, the Nelsons, use the area during the summer for wilderness and walking trips. They have a cabin on Thayer Lake, travel to and through the pond to the head of a trail which leads to Salt Lake. From this point they say they take the people to Angoon by boat. 1. Layout Aerial photos and aircraft observations were used to find a practical route from the pond to an elevation where the costs of extending the pipe would exceed its value. The route turned out to traverse a meadow to the first peak, a boggy area over the first divide and then follow a incised old stream bottom until it was possible to leave the stream at station 27+00 or so. The stream bottom is fairly soft and mucky and is about 50 feet wide over much of its distance which is similar in geometry to Thayer Creek which drains the lake. The sides and some of the bottom of the stream are covered with trees up to six feet in diameter. The banks of the stream are fairly steep in the order of 20 to 40% at their maximum. The selected route may not be the optimum as it may be possible to follow the stream a little further and breakout wi thout as high of a bank. However, as the stream bed was meandering away from the powerhouse the current location seemed best . 6 ., ."" .. .. .. .. • .. .. .. ,.. .. ... ... ., .. .. .. .. .. .. """ -"~~.~--"-----~---------------,------------ polarconsult Angoon Hydro Study With a relief of 47 feet in elevation and the hydraulic losses of the pipe it is impossible to syphon the water from the pond. A deep ditch would have to be excavated for a syphon. This ditch would be a minimum of 25 feet deep and 3000 feet long, providing it were possible to reduce the profile elevation below the hydraulic grade line from station 35+00 on. The only other alternative would be to drive a tunnel in the order of 3000 feet or so . The alternative selected is to pump the water over the divide and use the greater fallon the other side to generate sufficient power to run the pumps and provide the community with energy. This alternative is not the usual one used for a hydro plant as it involves more equipment, wastes some additional energy in pumping losses, requires larger, turbines and generators which have higher losses. However, in a situation such as Angoon's where there needed, where the ratio of pumping head and alternatives are expensive, then provide excellent economics. 2. Construction is to a more water than output head is pumping scheme is low may The construction of the diversion scheme is designed in a manner to use hand labor for the entire project with the exception of boats, and helicopters for basic transportation and a winch for pulling pipe and trees. Provided a good trail can be developed, 4 wheelers can be used for the smaller items.All of the parts and equipment items are sized to weigh less than 3,500 pounds which allows them to be lifted by a Bell 212 . Using hand labor will provide added employment to the community and will result in a project with very reduced environmental disturbance. From the ground it will be very difficult to see this project with the exception of the intake and a short section of the pipeline near it which will be 7 .. .. .. '" .. .. .. ... .. .. .. .. WI .. .. .. - ,,-------~--------------~------------ polarconsult Angoon Hydro Study visible from the pond. From the air only short sections of the pipe and trail will be visible and one will have to know they are there and be lined up with them to see them. The equipment will be quiet with the pumps under water and the turbines in a building . 3. Intake The intake for this plant will consist of four screened pipes with a floating fine mesh net on the outside to prevent ingesting some of the native cutthroat trout. Each intake will be equipped with a submersible pump. The water will be pumped through check valves into the pipeline which will cross the meadow up the hill. The intake will be constructed of prefabricated metal or treated wood which will be modularized in sizes easily handled by helicopter. Power to the intake will be transported by tree suspended cable hence underground in the meadow. There will be two transformers and four contactors located near the pumps which will be enclosed in a weather proof metal enclosure which will be painted green . Hemlock and spruce trees will be planted around the enclosure to screen it from the pond . 4. Pipeline From the intake the pipeline route for several hundred feet passes through grassy meadow hence through a soft surface boggy cut through the divide between drainage to the lake and to the inlet. From this point it travels along an ephemeral stream which has soft black organic material in its bottom. Once leaving the stream area it crosses out of the immediate stream drainage and continues on gently sloping ground which is forest floor with a bog along the way. The route is covered with a number of trees as shown in the photograph . The pipeline was planned to be constructed of 32 inch polyethylene pipe in the upper section with the use of 3/16 th inch steel from the 210 foot elevation to the 100 foot elevation where the power house is to be sited. Polyethylene 8 .. .. • ... .. .. .. • .. .. .. .. • polarconsult Angoon Hydro Study pipe was selected because it can be bent, can accommodate to the ground, has a low coefficient of friction, can be pulled in long lengths and if a tree drops on it will spring back to its original shape. Polyethylene was selected as it can easily accommodate temperature changes. The plan used for this project is to hand clear a narrow trail along the pipeline route. Then with shovels and perhaps a very small backhoe, construct a bench on the side slopes where needed for the pipe. In addition to the pipe bench which will only be 3 feet or so wide, a bench would be constructed for the foot and 4 wheeler access trail. Although the pipeline bench may require tree removal at intervals, the access trail construction can generally avoid removing many trees. The pipeline will be anchored with cable connected to the flanges, ground anchors or trees. Staging locations will be developed and the pipe brought in and stacked on skids by helicopters. A fusion machine will set up at one of these stacks and the pipe will be fused and pulled along the pipeline with a winch line. In the lower section of the pipeline the material will be steel. In this location it will be spotted with a helicopter, pulled into place a joint at a time and fillet welded. The steel pipe will be supported on timber fabricated from local felled trees. 5. Powerhouse The powerhouse which will be about 20 X 30 feet in dimension, will be constructed of wood or metal on a reinforced concrete slab. There will be five pumps operating as turbines in the powerhouse. These pumps will drive synchronous generators which will connect through two transformers which will raise the 480 volts to 7.2/12.4 Kv . The powerhouse will be equipped with alarms and a SCADA system and will have a programmable controller which will sequence 9 '. .. .. .. .. • .. • .. • III .. • ... .. .. ... polarconsult Angoon Hydro Study the system as to operation. To operate the system one of the pumps will start at reduced voltage, when the pressure reaches a certain point the pump will be advanced to a higher voltage and the turbine valve will open and the turbine synchronize to the line. At that time a second pump will turn on and a second turbine and so forth until all five turbines are operating. At that point the system will be producing about 625 Kw net . Assuming that there are 5% line losses the net at Angoon would be 594 Kw which at 95% availability will produce 4.94 million Kwh per year. With the pump pump-turbine scheme the power can only be controlled in blocks of 120 Kw net each. To control the frequency it is proposed to use a load governor. A primary governor with resistance heaters will be located at the powerplant. The amount of heating will likely be near 250 Kw. In Angoon control units will be located in strategic areas which will be capable of extracting the extra 3.5 million or so Kwh that is excess to current community needs. This amount of excess electricity can produce the equivalent of 125,000 gallons of fuel oil worth of heat per year assuming oil at 120,000 Btu per gallon and burnt at 80% efficiency. A variable flow francis turbines their generators $100,000 higher system can be built which would utilize two turning at 1200 RPM each. These turbines with will cost about $250,000 which is about than the pumps used as turbines. Their efficiency is about 4% higher . Using the scheme that was outlined, the system will operate continuously, only being turned off for maintenance or when water levels at the lake are low and extra discharge is needed for the pinks at the mouth of Thayer Creek. This constant operation at about 10 cfs per unit makes a constant flow of water available which can be used near the shore line or at 10 .. .. '," .. ., .. .. ... .. .. .. .. .. .. .. polarconsult Angoon Hydro Study Fresh Water Lake, or Salt Water Lake for hatchery or mariculture operations. 6. Transmission The transmission line which is about 6.5 miles in length is planned to be constructed as insulated cables suspended by a messenger from trees or on the ground in plastic, PE, duct . The tree cable has been used very successfully by Horner Electric Association who have 25 miles of 14.4/24.9 Kv tree suspended cable in service. The reason they use this cable is for environmental and costs reasons as part of the route is in a park. They have had only three squirrel outages, all in the same area, during the 15 years the system has been in operation. When a tree falls over the line the system is designed so it pulls the cable off of the supports without breaking it. Therefore it continues in operation unlike conventional overhead systems. With 25 miles of this cable inservice HEA reports only one tree incident per year and has to inspect the line once each two years . Crossing the channel to Angoon will be done with half inch or heavier thickness walled pipe with pulled in cable. The pipe wall will be so heavy that no 'supplemental weights will be required. The pipe will be protected with a coating, impressed current system and anodes at each end. A similar system such as this used for the water line failed. However, it is intended to search out a wider deeper location where water velocities are appreciably under the 16 mph reported to be found at the site of the current crossing . A small switching station will be constructed to tie in the transmission line to the Angoon utility system. This substation will be the metering point for the system . 7. Trail After engineering, the first construction item will be the trail. The trail which will be about 2.3 miles long will start 11 III .. .. • -II • .. .. ... .. oil .. .. .. .. .. .. polarconsult Angoon Hydro Study at one of the inlets off of Mitchell Bay. The starting location will likely be integrated with future fish hatchery plans. The trail will be designed and constructed so it can be used by small low tire pressure all terrain vehicles. It will be constructed with hand labor and will use planks, logs, corduroy, and geofabrics to cross the boggy or soft areas. The heaviest single item which will travel over the trail is a cart with a replacement generator. The cost estimate for the project assumes that 1/3 of the trail will require plank construction of treated materials. If cedar is readily available in the area, local trees can be used which could include the manufacture of planking on site with a bandsaw mill. 8. Potential The potential of the diversion site is substantial. It could be enlarged several times and with the addition of a small weir and controls at the lake mouth the capacity could be increased to perhaps almost 2 Mw. The water from this site will flow to inlets in Mitchell Bay where a hatchery and mariculture can be sited which will provide employment and income for the local people from a renewable resource. The water can readily be diverted to Fresh Water Lake and to Salt Lake and there is a potential which if environmentally and for a red salmon rearing area biologically favorable could result in substantial income to the community. Access to the site is from protected waters versus the alternative which is out in Chatham Straits. Additionally this location can be easily hidden from most normal traffic by boats and aircraft. Because the power line passes through an area which is the most likely source of water for the community, power and communications can be made available to those facilities along the route, which should save money . The negative part of this scheme is that it is in a wilderness area and secondly has more equipment to maintain. However, as 12 • • .. .. .. - • .. .-.. .. ... .... .- -... • .. .. • ... .. polarconsult Angoon Hydro Study pumps and contractors are highly reliable it is not believed that the maintenance costs will be much more expensive than those for more conventual facilities . Draining the beaver pond will result in a muddy shore line which will take several years before the grass reestablishes itself. It should result in a beautiful grassy meadow until the trees reinvade the area. Additional water in the creek from the plant discharge will result in some increases in erosion for a short while until the banks and bed restabilze themselves. Since most erosion occurs during flood stage and the amount of water may not be significantly greater it is likely this will not create a real problem . c. Tunnel The Thayer Creek or Tunnel Scheme is a modification of the one proposed by Harza Company. The Harza proposal was a concrete dam with a net head of 45 feet, two propeller turbines, with a firm capacity of 210 Kw, a installed capacity of 400 Kw, a flow of 128 cfs and generation of 1.575 Mwh.The essential differences between that system and the new scheme are that a tunnel is proposed rather than a dam, that the water will not be returned to the creek, that the turbines will have near 4 times the head hence producing more power using less water, that a load governor is to be used and finally the cost of the system is much reduced, and the power output much increased . 1. Layout The system layout is as shown on the sketches in the appendix . It is comprised of a tunnel whose mouth is about one half mile north of the mouth of Thayer Creek and whose entrance is above the rapids at the 200 foot contour level. From the tunnel a penstock follows the fall line directly downhill to the 13 • .. .... .. • .. .. .. .. .. .. .. • -.. • .. • .. • .. ,II .. T1 polarconsult Angoon Hydro Study powerhouse on the banks of Chatham Straits. The tailrace drains directly into the strait . 2. Intake The intake will be a modification of the tunnel entrance to the stream. The rock will be presplit to a vertical face and steel H beams will be set to support °a 20 foot or more long trash rack, stop log system for screening debris and shutting off the tunnel when necessary. Concrete quantities will be reduced to the minimum required to seal or level critical locations in the structure . 3. Diversion weir A diversion weir about 4 to 5 foot high will be used to get the water into the tunnel entrance. The weir will consist of steel H beams about 10 feet on center which will be cemented into the rock. The holes will be excavated with shaped charges or conventional drilling and blasting. Each of the H beams will be equipped with a support for planking to walk out and remove or add the wooden stop logs. A small hoist system will be devised so the stop logs can easily be removed to flush out the gravel and rock as it accumulates behind the planking. 4. Tunnel A geologic report states that the material where the tunnel is to be excavated is marble with bands of shist. The foliation strikes NW, parallel to the coast, and dips 40 0 NE. There are a strong set of right angle vertical joints and another set of N-S vertical joints. The rock appears from this report to be of a type that would not need extensive supports and should be easy to tunnel . The tunnel is to start from below the 200 foot level on the seaward side of the hill and extend about 4000 feet to the right bank of the creek. The tunnel will be a size selected by the tunneler which will be a 5 x 7 foot or larger. The tunnel 14 .. ... .. .. ... .. .. ... .. .. .,.. ... ,. .. -.. .. .. .. .. ... .. ... ,. i. ttll_at II -f .. polarconsult Angoon Hydro Study grade will be less than one percent and all of the tailing rock will be dumped under the trees at the entrance . To keep tunneling costs down the contract will be written on a performance basis with a time and material clause for special conditions like unstable ground that calls for sets, grouting, shotcrete other remedies. The risks will be carried by the community rather than the contractor. Tunneling can also be done with force account labor and if this is the case it is projected that the costs could drop from $375 per foot to $200 per foot . For a small project of this type, a team of miners equipped with a mucker, track, locomotive, 20 cars, air legs and a compressor could earn considerable amounts of money and still construct a very economical tunnel. When the 10,000 AJ adit was driven at Juneau a crew of 3 mem drove 10.5 feet a shift with a mucker, hand tram and air legs. Small tunnels generally do not require the support system larger ones do and this tunnel because it is near the top of the hill is less likely to have excessive high pressure water that can be found in other tunnels . 5. Pipeline The pipeline will be made of 32 inch polyethylene pipe, which lS flanged and will be winched up the hill and bolted into place. The 1000 foot pipeline will have flanges which will provide the locations for cable connections to rock and ground anchors to restrain the pipe . 6. Powerhouse The powerhouse will be a reinforced concrete slab with either wood or metal building construction. The powerhouse size is estimated to be 20 x 30 feet and will house four 10 inch pumps run as turbines. The installed capacity of the system will be near 600 Kw and the output of the pumps at 170 feet of net 15 .. .. • .. • - ... • - • ... • ... • "" - .. • ... • .. ... polarconsult Angoon Hydro Study head will be 595 Kw. The system will generate about 4.71 Mwh per year using 95% plant availability and 5% line losses . 7. Transmission The transmission line route is "slightly shorter, 6.2 miles, than the diversion route but crosses steeper country and areas which have cliffs. Therefore, it "likely will be more expensive. Because it is less expensive and easier to repair tree cable was selected. Submarine cable was investigated but areas with good bottom conditions are probably over 600 feet in depth which requires special cable, splices and laying equipment. This transmission route also will require a crossing to the peninsula that Angoon is on. The crossing will be done further north than the narrows where velocities are low enough to utilize standard cable . A small switching and metering station will be needed to connect to the community distribution system . 8. General Discussion The tunnel scheme has the advantage of being on land already selected by the Angoon Native Corporation, Kootznoowoo, Inc., which will make it easier to initiate the construction of a power plant. The tunnel scheme is simpler in operation then the diversion scheme and can be readily added to with additional penstocks, as the minimum sized tunnel is more than sufficient. Although the tunnel scheme is more expensive it should be somewhat less expensive to maintain. Because of the exposed location, lack of space, the tunnel scheme will not likely support a large mariculture operation. It could support a hatchery however. Access to the tunnel scheme is not in protected waters and during winter storms it may not be possible to reach the site. Therefore, this scheme may call for a permanent operator/caretaker during winter periods . 16 .. .. .. .. .. ... .. .. .. .. .. - ... .. .. • .. .. .. It polarconsult Angoon Hydro Study VI. ESTIMATE Two estimates where made. One for the Diversion system and one for the Tunnel system. Both estimates qssumed the use of local labor at 15$ per hour with 35% fringes, insurance and social securi ty. The assumption because of travel time that only 6 working hours per day is available and that travel is by boat . All hand labor is to be used at each site with the exception of helicopters to bring in pipe, lumber and powerhouse materials from the beach. There is to be expert help during construction of various features such as installing the equipment, and fusing the pipeline . For the tunnel scheme is estimated on the basis of being done with a performance contract with little control from the communi ty. The tunnel drilling is to be arranged so a small group of miners can bid and do the work without the heavy burdens and guarantees which are typical of institutional organizations . The turbines for the system were estimated on the basis of using pumps. Francis Turbines will add $100,000 to $150,000 to the costs. Pumps are inexpensive, light, easy to install and easy to maintain. They are highly reliable as they have only two moving parts . Contingencies are allocated based on the degree of uncertainty in the estimate. Material contingencies are considerably lower as their probable costs were lower. All costs are based on a 1990 construction start and based on a single barge lift to the site . 17 _ .. _. __ .------------------_. ------ poiarconsult Angoon Hydro Study .. .. .. .. .. ESTIMATE, DIVERSION SYSTEM -.. ITEM COST CONTINGENCY TOTAL MD Trail 79 12 81 150 .. Pipe Mat. 334 33 367 .. Pipeline 254 51 305 800 Intake, Mat 100 10 110 .. Intake 102 21 123 100 Turbines 150 15 165 .. Powerhouse 138 21 159 .. Powerhouse, lab 79 16 95 35 Substation 10 2 12 15 ... Transmission 277 42 319 300 .. Crossing 40 8 48 40 Switching station 10 2 12 10 .. Direct Csts 1573 233 1796 1450 .. Total Csts 1796 Engr + Admin, 15% 269 .. TOTAL $2065 • * All values in $1000's .. , .. .. .. • ... 18 -.. • • .. .. .. .. - ... • .. ' . ... .. • polarconsult Angoon Hydro Study ESTIMATE, TUNNEL SYSTEM ITEM COST CONTINGENCY Tunnel 1500 300 Plug 21 4 Pipeline 107 22 Diversion 22 7 Intake 36 8 Turbines 160 16 Powerhouse 138 21 Powerhouse, lab 79 16 Substation 10 2 Transmission 250 38 Crossing 40 8 Switching station 10 2 Direct Csts 2373 444 Total Csts Engr + Admin, 15% TOTAL * All values in 1000's Whether the contractor will hire local work is not known. Therefore, the represents 3 men working about a year TOTAL MD 1800 600 25 31 129 140 39 56 44 78 176 159 95 35 12 15 288 280 48 40 12 10 2827 1285 2827 424 $3,251 labor for tunneling 600 man days which is a estimate only. Should the community decide to do their own tunneling, then these hours would be guaranteed. It is estimated that by using non contract work the tunnel costs could approximate as little as $800,000 or the Tunneling System costs would total $2,411,000 . 19 .. .. .. • .. .. .. .. III .. III .. .. .. .. .. " .. polarconsult Angoon Hydro Study VII. CONCLUSIONS There are two hydro systems that can be built that use the Thayer Lake resource. Either of them will provide large amounts of energy to the community. The community can use the extra energy for space heating, gr~enhouses, operating a hatchery, freezer plant for fish and sea food, and for a mariculture operation. The cost of both plants is near a 10 times multiple of the money now 'being given to the community for power cost equalization and 20 times the value of the fuel. Each of these hydro plants will be less expensive to operate than the alternative diesel plant. But the diesel plant will have to be retained for standby as these plants may need to be shut down for maintenance and if there is a failure of the transmission line. Each of the systems will require considerable local labor during its construction and if the plants were built by contractors their costs would increase considerably. The diversion scheme uses about 1450 man days of labor versus the tunnel scheme which uses 1285. Adding another 1,000 man days of labor would represent a cost increase of $170,000 which shows that if the labor hours increase the cost increases will not be great . The diversion scheme with its continuous supply of water to a protected area can provide the basis for a hatchery and future mariculture which can provide income and employment for members of the community for countless years in the future. Freshwater Lake could receive some of the water and become a rearing ground for highly valuable red salmon. The diversion schemes power line will pass close to a viable source of water for the community. In addition during the construction of the power line it would make sense to do the expansion for the water lines as workers, helicopters and other logistic support will be available. Further, 20 ... .. .. .. -/If .. .. .. .. .. .. .. • .. .. - .. .. ... .... .. .. polarconsult Angoon Hydro Study electricity, telemetry and control functions can be done over the same circuit . The major problem with the diversion scheme is the fact that it is in a wilderness area. But when consideration is given to the clean nature of the project, the obligation of Congress to the community, and the arbitrary nature of the current boundaries, the resolution of this matter may not prove difficult . Technically, neither the diversion scheme nor the tunnel scheme is difficult. Operationally, the diversion scheme to start up will require sufficient diesel generators on line at Angoon to start one of the pumps. Since the system will seldom be shut down it is not likely that start ups will be required more frequently than once per year or so. Both systems can be expanded to about 3 times their initial output. The tunnel scheme will be the least expensive to expand. Both systems will have to deal with the pink run at the mouth of Thayer Creek and if provided with a very modest amount of storage, perhaps two feet, can guarantee sufficient water flows so as to have little effect on the resource . All of the calculations are based on a synthesized water record. The schemes are not sensitive to large variations in the values of these records . Both schemes if economically viable will need more data to progress to a greater level of accuracy in the cost estimating. A stream gage should be installed on the creek and perhaps several rain gages for basic data. For the diversion scheme some surveying, of the pond, and the pipeline route would allow more accurate determination of the pipeline costs. For the tunnel scheme geological work which would include some seismic surveys and better delineation of the intake areas 21 .. .. .. .. ... .. • , .. .. .. .. • .. • • • polarconsult Angoon Hydro Study would be appropriate. Investigation into velocities for the cable crossing area would be very useful to determine where a safe crossing can be made . The community of Angoon can build one of these hydro plants which will provide income during the construction and displace the cost of diesel fuel during its life which should be substantial. A hydro plant equipped with load governors can be used to provide supplemental heat in the town up to the capacity of the machines. A hydro facility will isolate the community from rate and reductions in shock caused by increases in fuel costs power cost equalization funding. With decreased hydro can community needs make favorable for power during the summer the the addition of a modest freezer facility. The Diversion system can make it possible for the community to increase the harvest of fish which can result in employment and income for generations of future residents . 22 .. .,. .. ... .. • .. • ... ... .. till ... polarconsult Angoon Hydro Study VIII. RECOMMENDATIONS Looking at the long term future for the community assuming that low cost money is available, the economic projections will likely show the project is feasible. With additional engineering and the conservative nature of the estimate it is likely that some of the costs can be reduced. But before reducing costs additional basic data is needed. Therefore, assuming that economics show the project feasible at the current figures, and assuming that a project can be selected, the field work discussed in conclusions should be done. In addition to this field work, a more accurate cost estimate should be provided which will include further details on the project's technical features. To further understand project benefits a analysis should be made on the added uses of low cost power in the community and what the value of this energy will have for the community . 23 APPENDIX • .. .. II .. II .. II II • .AI .. • • • .. II .. INTERVAL 100 FEET GEOOETIC VERTICAl OATUM OF 1929 IN rEET -DATUM IS M(AN LOWER LOW waTER TH( AfIiIIWOllMATl UN[ OF' MEAN HIGH "1'IJI "lOG( IJf nil( IS _IMATtL, Il F'£[T E BY U. S. GEOLOGICAL SURVEY NVER. COLORADO 80225. DR RESTON. VIRGINIA 22092 MAPS ANO SYMBOLS IS AVAILABLE ON REQUEST LOCATION .M·AP "~ , . "'''-0 .. ~--QI.WlIWIGlE LOCATlON ROAD CLASSIFICATION Unimproved dirt ••••••••• SITKA (C-2), ALASKA 57134-E3-Tf-063 1951 LIMITED REVISIONS 1983 THAYER LAKE PIPELINE o 250 500 750 1000 FEET • SURVEY POINTS /---, / /" ~-----z" / ...... , C / -, / 1\/ / \ / I \ ~ , fJ.J \. .". 5 -~, / 10 ......../ ,.,. "'". I.>-~ / ,~ -.", l!!i -.J 1& I ~--.." - ~ / / I I I I , f I , I I I / polarconsult alaska, inc. ENGINEERS -SURVEYORS -ENERGY CONSULTANTS 1503 WEST 33RD AVE.-ANCHORAGE, ALASKA 99503 JULY 17, t-989 \ s::: ~ o :::c r Z m SHEET 1 r Z m c Z OU1e. ., --- - - - - - -GUL;;.e..:!. ~ -., " ~-~~-~~--; \ \ \ I , \ \ \ ;I'" ,--fill!" ..... ...... ..... "- POWER HOUSE " ELEV.100; THAYER LAKE PIPELINE ~ ...... " " \ \ " , --o --250 500 FEET 750 100Cf polarconsult alaska, inc. ENGINEERS. SURVEYORS. ENERGY CONSULTANTS 1503 WEST 33RD AVE.-ANCHORAGE, ALASKA 99503 JULY 17, 1989 " SHEET 2 GULL Y PROFILE r --PHOTOGF AMMETRIC / PROFILE , 3001-----+-----I---+----+---+------J---+---'\·-+-,~-+__-___I_--+__-_+_-____I,__-__+_-__+___t ~ '" /~ "---~ \\ 200r-------~------_+--------~------~------_+--------+_------~------~--------+_------~------~~------+---~--~------~r-------+_--~ "'~ '~ 100~----~~------~----~~------~----~~------~------~-------~------+_------+_------+_------r_------+_------+_------~~--_. ~ w w U- 500 I 1000 1500 2000 FEET '<to roO) zro O~ -> .-w <.....J '-w C/) 2500 I. !3000 I 3500 4000 00 < Z)( z'" z Q< 0'" 0 -. i= ~~ ~> cw < ~ .... .-We") (l)W C/) .....J'<t W 4500 PIPELINE ROUTE PROFILE 5000 5500 6000 6500 7000 polarconsult alaska, inc. ENGINEERS e SURVEYORS e ENERGY CONSULTANTS 1503 WEST 33RD AVE.eANCHORAGE,ALASKA99503 JULY 17,1989 7500 ( W C/) ::J. 0° :r:~ a:::. w> ~~ OW a.. SHEET 3 Figure 1. Looking at the S.W. arm of Thayer Lake. The intake is located at the upper left of the photograph. Figure 3. Looking S.W. alon~ the still water anchorage towards Angoon. TransmissIon line route on right. Figure 2. The intake is on the left in the small pond, Thayer Lake is on the right. __ _ Figure 4. Transmission line continuing to a turn point and then crossinQ the water to the villaQe of AnQoon. Figure 5. Aerial view of the small inlet on the end of Thayer Lake. Note the channel and beaver dam. Figure 7. View of channel and beaver dam, looking towards the pond. Figure 6. Mouth of the channel between Thayer lake and the pond looking out onto Thayer Lake. . Figure 8. Intake location on the pond. Figure 9. Pipeline route over first ridge. Figure 10. Typical forest; trees reaching six feet in diameter Figure 11. 190 kW pump turbine similar to that for Angoon. INTAKE TUNNEL ROUTE PENSTOCK POWER HOUSE TRANSMISSION LINE TUNNEL ALTERNATIVE 35' 2080000 FEET , , \ ',- , \ \ \ \ \ Danger PI 31 " ! ( of ./ ,0 18 558 57°30 '---t-:;-:;-;::,,,,,,,,~~---~----'----+-'---·'\'-------L=~~-------cCJ"L.:.:.-":--I 134040 2490000 FEET Mapped, edited, and published by the Geological Survey Control by USGS and NOS/NOAA Topography by photogrammetric methods from aerial photographs taken 1948, field annotated 1951. Map not field checked Selected hydrographic data compiled from NOS charts 17320 and 17339 This information is not intended for navigational purposes Projection and 1000-meter grid ticks shown in blue, Universal Transverse Mercator, zone 8 10,OOO-foot grid ticks based on Alasl<a coordinate system, zone 1. 1927 North American Datum To place on the predicted North American Datum 1983 move the projection lines 38 meters north and 106 meters east 35' ~ ~ ~ f ~ ~ := J ~ APPROXIMATE MEAN DECLINATlON,1951 3000 IOTR I TURBINE INDUCTION GENERATOR ASSEMBLY FOR GENERATION UNLIMITED NEWPORT BEACH , CA. • • i"~ .800 :.7to .. -j J , , ~ __ .. _ ._.~..2t1()_ i~ '.\oJ ... _~_4iJQ. ! ! . ---"--1--... -.~ , ! , ' -+ --1--", .-.. --.-. ., .-. , .,. .-.---... ~.-•• .!...--. t--~·'-·······~ t· i ' J I T '\. -----.~-.-.+-.- !\ .. 1.. , ~-.-.~~ ... -~ -. .. -.-.--'-;----.-.~.--- L· .... sllO·K,w .. ·----- ! < _. ! , .' ----~--J-.----i.------~ .... --.~ ~OO k:W:! 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