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Home My WebLink Aboutltr 071708 polar to dnr#1.-polarconsult alaska, inc...... ".__ ~ ENGINEERS· SURVEYORS' ENVIRONMENTAL CONSULTANTS July 17,2008 JILLRn:SE INVEST:\IENTS & BROKERAGE 1150 S COLONY WAY #3 PMB 183 PALMER, AK 99645 Subject: Delia Creek Project Description Dear Jill Reese, I have prepared the following description for the Delia Crcek Hydroelectric Project. As you know we are in the pennitting phase of the project and have yet 10 perform a eomplete design so some minor changes should be expected. Project Description Hatcher Pass Motherlode Lodge, LLC (HPML) plans to construet a 50 kW run of river hydroelectric project on Delia Creek, IDeated in Hatcher Pass, Alaska. The Delia Creek Hydroelectric Project (Projeet) will provide electrieity to the Motherlode lodge which is owned by HPML. This energy will displace diesel fueled electrical generation. There are four basic components that make up the run of river hydroelectric facility. They are: • Intake -Also referred to as the diversion structure, the intake consists of a small dam (weir) that impounds the water in the creek so that it can be diverted into the pipeline. This weir will be smaller than a typical beaver dam. Because of debris that is carried along in the stream, a desander and screening box is used between the intake and pipeline to ensure only clean water enters the pipeline. With the exception of an equipment storage shed, the screening box is almost entirely buried. • Penstock (pipeline) -Thc penstock conveys water from the intake down to the powerhouse. The penstock is designed to minimize energy loss as it transports thc water down to the powerhouse. Normally, the energy of the water falling dovmhill is expended by friction. turbulence, and noise in the creek bed. The penstock minimizes the energy losses on the way to the powerhousc so that there is a substantial amount of energy in the fonn of water pressure available to produce power. The penstock will be entirely buried. • Powerhouse -The primary purpose of the pov..TThouse is to house and anchor the turbomachinery. This consists of the water turbine, ,...·hich is coupled to thc electrical generator. the generator is wired to the power line via switchgear. The powerhouse will also contain miscellaneous mechanical equipment such as turbine controls and project maintenance equipment. • Power line -The power line conveys the electrical energy produced by the generator to the utility's power distribution system. Because the powerhouse is located very closc to the existing diesel generators there won't be a need for a typical transmission line. This project is a run of river project. Therefore. it does not store water and can only use the water currently available in the creek to generate electricity. Run-ofriver projects are 1503 WEST 33RD AVENUE' SUITE 310 ·ANCHORAGE. ALASKA 99503 PHONE (907) 258-2420' FAX (907) 258-2419' HOMEPAGE wwwpolarconsult.net POL\RCONSULT ALASKA, INC. 7/17/2008 advantageous because they are less costly to build and they do not change the amount of water flowing below the project which helps protect fish and wildlife habitat. The disadvantage of run-of-river projects is that they cannot utilize all of the water in the creek during high flows, and thus cannot generate as much power as a storage project (a project with a large dam). Thc actual volume of water used and power generated by this project will vary seasonally, with full output generally occurring from May through October and then declining during the winter to a minimum powcr output occurring sometime in April. The total water used and power generated will also vary slightly from year to year depending on the amount of precipitation and weather. The peak capacity of the Delia Project is approximately 50 kW with an annual energy production of about 260,000 kWh. Location The project will be located directly across the Little Susitna River from the Motherlode lodge. The powerhouse is located next to the Little Susitna River on HPML property. The intake and penstock are located in and along the Delia Creek drainage valley. Below is a detailed description of each project component. Concept illustrations and preliminary engineering plans are available separately. Intake The project intake will consist of a short weir (diversion structure) of concrete, timber, stone, or metal across Delia Creek. The weir will span the entire creek up to the flood stage (a distance of about 20'). A spillway will be built into the weir so water in excess of project flows will flow over the weir within the banks of the creek. The weir will be built to the lowest height needed to allow water to flow slowly and smootWy through the intake grates of the screening box. These grates will prevent large debris and animals from entering the screening box. Preliminary design height for the weir is 4'. Water enters the screening box at a low enough velocity that material such as sand and gravel will be filtered out. Lcaves and floatable debris will be trapped by a 1/4" screen that the water passes through. When either the screen or the box accumulates too much debris to pass the water needed for the project a flush will occur. This involves opening a submerged gatc(s) on the screening box that will allow water to briefly flow out of the box very quickly taking the accumulated debris with it and discharging just below the weir into the creek. The screening box will be designed to handle approximately 2.0 cfs of water, and will be mostly below grade. Atop of the screening box will be a shed to house the level measuring and gate flushing equipment. The shed will be a very small structure. An air vent will also protrude above ground just downstream from the screening box. The vent will have an inverted U at the top and is screened to prevent debris from entering the penstock. Access to the project intake will be along the pipeline route. Construction equipment will cross the Little Susitna at the nearest ford from the powerhouse. Maintenance access will bc on foot or four wheeler utilizing the bridge to cross the Little Susitna. The bridge will bc gated to allow only foot traffic by the public. PAGE20F3 Project Penstock Upon exiting the screening box the project water is conveyed to the powerhouse through a pipeline called a penstock. The penstock will be an 8 or 10 inch diameter high density polyethylene (HDPE) plastic pipe with some steel pipe possibly located near the powerhouse. The pipe parallels the north side of the creek downstream from the intake descending to the powerhouse. The total penstock length is about 2,600 feet. The penstock may be exposed or partially buried in the upper section. The lower sections will be entirely buried except where it crosses the Little Susitna River. Conduit will be buried with the penstock to provide power and communications to the intake. The bridge that will carry the pipeline aeross the Little Susitna River will be very similar to the old bridge. Our drawing that we provided you showed some piling but upon further review we will eliminate those piles and simply span the entire river. The existing footings that are in plaee from the old bridge can be utilized for the new bridge. Project Powerhouse and Tailrace The powerhouse will be located near the banks of the Little Susitna River on HPML property. The powerhouse will be accessible by the existing driveway that descends a short distance from Hatcher Pass Road. The powerhouse will be constructed on gravel and concrete fill. Native material excavated from the powerhouse site will be deposited in a disposal area on HPML property. The powerhouse will house the turbine, generator, switchgear, and controls. The physical size of the building is dictated by the size of the equipment housed which is not yet known. However, previous turbine designs similar to this project suggest that the building will be no larger than 15 by 15 feet and less than 10 feet tall. The construction materials willlikc1y consist of concrete block walls and a wooden roof. The generation equipment will consist of a single turbine and generator with a rated capacity of about 50 kW each. The turbine is called an impulse turbines (also referred to as a Pelton wheel). The turbine has nozzles that discharge the high pressure water from the pipeline onto buckets arranged around a shaft. The shaft of the turbine is then directly connected to the generator which converts the rotational mechanical euergy to electrical energy. After exiting the turbine, project waters will flow through a grate structure designed to keep animals and flsh from entering the turbine. Water will then flow through the tailrace, which will be a rock-lined ditch, to the Little Susitna River. If you have any questions regarding this Project please feel free to contact me. Sincerely, Daniel Hertrich, PE PAGEJOFJ