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HomeMy WebLinkAboutTunnel Muck Disposal Assessment Bradley Lake Hydro Project APA 1987BRA 117 Alaska Power Authority LI BRARY COP Y TUNNEL HUCK DISPOSAL ASSESSMENT BRADLEY LAKE HYDROELECTRIC PROJECT ALASKA POWER AUTHORITY FEDERAL ENERGY REGULATORY COMMISSION PROJECT NO. 8221-000 Prepared by STONE & WEBSTER ENGINEERING CORPORATION ANCHORAGE, ALASKA JANUARY 1987 DATE BRA 117 HIGHSMITH #~222L ISSUED TO ' I r ) I PRINTED IN U.S.A. TUNNEL MUCK DISPOSAL ASSESSMENT BRADLEY LAKE HYDROELECTRIC PROJECT ALASKA POWER AUTHORITY FEDERAL ENERGY REGULATORY COMMISSION PROJECT NO. 8221-000 Prepared by STONE & WEBSTER ENGINEERING CORPORATION ANCHORAGE, ALASKA JANUARY 1987 t,l r I TABLE OF CONTENTS Section 1.0 2.0 3.0 4.0 5.0 6.0 2-1153-JJ 2. 1 2.2 2.3 2.4 2.5 2.6 3. 1 3.2 3-3 3.4 3.5 TABLE OF CONTENTS Section Title LIST OF TABLES INTRODUCTION TECHNICAL EVALUATION Adjacent to Marshalling Yard Waterfowl Nesting Area Lower Concrete Batching Area and Clean Fill Disposal Sites Northwest Portion of Lower Construction Camp Martin River Borrow Pit Barge to Homer ENVIRONMENTAL EVALUATION Adjacent to Marshalling Yard Waterfowl Nesting Area Northwest Portion of Lower Construction Camp Martin River Borrow Pit Barge to Homer ECONOMIC EVALUATION RECOMMENDATIONS AGENCY CONSULTATION i Page No. ii 1-1 2-1 2-1 2-2 2-3 2-3 2-5 2-5 3-1 3-1 3-2 3-2 3-3 3-4 4-1 5-1 6-1 LIST OF TABLES Table 1 2-1153-JJ LIST OF TABLES Subject Tunnel Muck Economic Evaluation ii SECTION 1.0 INTRODUCTION 1.0 INTRODUCTION The power tunnel for the Bradley Lake Hydroelectric Project is pres-ently designed to have a 13 feet excavated diameter. However, to encourage the most cost-effective contractor bid an excavated tunnel diameter of up to 15 feet will be allowed as part of the General Civil Construction Contract bidding documents. A 13 feet diameter bore produces 6.9 cubic yards of muck per foot of tunnel, a 14 feet diameter bore produces 8. 0 cubic yards per foot of tunnel, and a 15 feet diameter bore produces 9.2 cubic yards per foot of tunnel, assuming a 40 percent bulking factor. With limited compaction and an 18,760 feet long tunnel, an excavated tunnel diameter of 13 feet would produce about 129,500 cubic yards, a 14 feet diameter tunnel about 150,000 cubic yards, and a 15 feet diameter tunnel about 172,600 cubic yards of tunnel muck. In addition, several tunnel alignments can be selected by the contractor. Assuming a 15 feet diameter tunnel and a tunnel grade which produces the maximum amount of tunnel muck, up to appro~imately 172,600 cubic yards of tunnel muck could result from the tunnel excavation. It is the Alaska Power Authority's requirement that the tunnel muck disposal be in a suitably permitted spoil area. Tunnel muck produced by the tunnel boring machine or by blasting is clean, poorly graded, angular rock material ranging in size from sand particles to rock 3 feet in diameter. The largest majority of tunnel muck material is angular, crushed stone 1.5 to 2.5 inches in size. Tunnel muck was originally designed to be used in construction of the waterfowl nesting islands and permanent airstrip. Construction of the islands will require about 65,000 cubic yards of tunnel muck. With the originally proposed permanent airstrip now deleted from the project design, another suitable disposal site must be located. The size of the required disposal area depends on the depth to which the tunnel muck can be spread and compacted. Although a 20 percent volume reduction could be obtained by compaction, for ease of reference all volume calculations assume no compaction. Assuming 172,600 cubic yards 2-1153-JJ 1-1 of tunnel muck can be spread in a 6 feet thick layer in a single disposal site, about 18 acres would be required. A 10 feet thick layer of tunnel muck would require about 11 acres. On-site investigations have resulted in identification of several possible disposal sites for the tunnel muck. These disposal sites are: 1. Adjacent to the marshalling yard; 2. In the waterfowl nesting area; 3. In the lower concrete batching area and clean fill disposal sites; 4. Northwest portion of the lower construction camp staging area; 5. Martin River borrow pit; and 6. Barged to Homer. The purpose of this assessment is to evaluate the technical, environmental, and economic merits of the proposed disposal sites, and to recommend a suitable disposal site. 2-1153-JJ 1-2 SECTION 2.0 TECHNICAL EVALUATION 2.0 TECHNICAL EVALUATION 2.1 Adjacent to Marshalling Yard The major portion of the marshalling yard will be constructed from rock excavated from the powerhouse. The marshalling yard is about 300 feet wide by 500 feet long and is located on the south side of the powerhouse tailrace. There is an area of tideland between the marshalling yard and the shoreline north of the permanent camp which is approximately 160 feet wide by 320 feet long (about 1 .2 acres) that could be used as a disposal site for tunnel muck. Expansion of the edge of the marshalling yard south to the rock bluffs would provide a greater work area as well as provide a nearby depository for a portion of the tunnel muck. Approximately 23,000 cubic yards of tunnel muck could be deposited in the area if it was brought to the level of the marshalling yard at elevation 18. Alternately, up to 65,000 cubic yards could be deposited if both the marshalling yard and adjacent area were filled to elevation 30. The latter fill depth would bring the fill to the elevation of the adjacent permanent camp area. However, raising of the marshalling yard to elevation 30 would make it too high and limit its intended purpose for servicing the tunnel portals. For the quantity of fill that could be deposited in this area, the haul distance would be short as it is immediately adjacent to the tunnel portal. Most tunnel muck in this area could be placed by extending rail car tracks from the tunnel. However the area adjacent to the marshalling yard is required for use as settling ponds for tunnel water treatment and settling of suspended solids. Two parallel primary settling ponds would be constructed out of tunnel muck or shot rock (Drawing 15800-FY-262A). Each primary pond would discharge into a single polishing pond. The polishing pond would be separated from Kachemak Bay by a small dike over which treated tunnel water would be discharged. Each pond would be equipped with sorbent booms. The two primary and single polishing settling ponds 2-1153-JJ 2-1 require approximately 14,250 cubic yards of tunnel muck for construction. The ponds could be formed of compacted free-draining rock material. A pond liner would not be required since the granular tunnel muck material used in construction of the ponds would act as a filter. Use of the area adjacent to the marshalling yard for either settling ponds or tunnel muck disposal requires culverting of the outflow from Powerhouse Creek beneath the marshalling yard to an outflow point near the tailrace. About 240 feet of 84-inch diameter CMP culvert will be required. 2.2 Waterfowl Nesting Area The waterfowl nesting area adjacent to the access road could be used as a disposal site for excavated tunnel muck. If the access road between Sta. 521 and Sta. 557 were widened on the waterfowl nesting area side from 28 feet to 75 feet and brought to elevation 19, approximately 88,000 cubic yards of tunnel muck could be deposited. However, widening of the access road would require lengthening of ten 48-inch diameter CMP culverts by 47 feet and relocation of ten concrete drop boxes. Round trip haul distance would range from 0.8 to 2 miles. Increased road widths in this section of the access road would allow opposing large truck traffic to pass unobstructed. Alternately, widening the access road between Sta. 510 and Sta. 532 from 28 feet to 75 feet on the Kachemak Bay side by depositing tunnel muck to elevation 19 would provide for spoil of 53,600 cubic yards. Widening the access road on the Kachemak Bay side would provide a potential landing strip 3,600 feet in length. Widening of the access road would require lengthening of one 24 inch diameter CMP culvert, one 36 inch diameter CMP culvert, and three 48 inch diameter CMP culverts by 47 feet. Existing riprap on the Kachemak Bay side of the access road would require either removal and replacement after spoil of tunnel muck or covering the existing riprap with tunnel muck and placement of 2-1153-JJ 2-2 additional riprap over the tunnel muck. Round trip haul distance would range from 0.5 to 1.3 miles. Increased road widths in this section of the access road would allow opposing large truck traffic to pass unobstructed. Tunnel muck will be used to construct the waterfowl nesting islands. Construction of nesting islands will not take place until near the end of the construction period during the rehabilitation contract. Approximately 65,000 cubic yards of tunnel muck could be temporarily stored in the northeast corner of the waterfowl nesting area next to the access road for later use in island construction (Sketch 15800-FY-S55-1). Tunnel muck would be placed to elevation 19 in a 1.25 acre area behind an approximately 650 feet long dike and allowed to drain and settle. The dike will act as a filter for draining tunnel muck. An additional 4,000 cubic yards of tunnel muck would be used to raise the level of the existing dike between the dredge disposal area and the waterfowl nesting area. This dike would be raised from approximately elevation 10 to elevation 18 to contain future dredge deposits. Disposal in the waterfowl nesting area for dikes and temporary storage for later construction of nesting island would total 69,000 cubic yards of tunnel muck. Round trip haul distance would be about 1 mile. 2.3 Lower Concrete Batching Area and Clean Fill Disposal Sites Insufficient space will remain in the lower concrete batching area and clean fill disposal sites along the access road between the powerhouse and construction camp to serve as disposal sites for tunnel muck. 2.4 Northwest Portion of Lower Construction Camp The northwest portion of the lower construction camp is presently being used as a log storage area (Sketch 15800-FY-S56-1). Ultimately this and the adjacent area will be used for contractor staging and laydown. The present design calls for the 10 acre northwest staging area to be 2-1153-JJ 2-3 brought up to grade at elevation 12 with Martin River fill to raise it above the elevation 11.4 maximum high tide. Also, because less topsoil was recovered from the lower construction camp area than originally anticipated, the northern portion of the topsoil storage area would also be available as a tunnel muck disposal site. Two alternate overlapping 10 acre areas (totalling about 15 acres) are shown on Sketch 15800-FY-S56-1. The entire northern portion of the lower construction camp has strong potential as a disposal site for tunnel muck. Within the clearing limits of the lower construction camp boundary, the northwest staging area could contain a minimum of 242,000 cubic yards of tunnel muck if brought to the design elevation of the adjacent access road at elevation 22. The drainage ditch paralleling the access road would be maintained. Shot rock dikes would be built on perimeter boundaries, where necessary, to contain and filter draining tunnel muck. Sorbent booms would be provided at drainage culverts to collect petroleum products that may drain from the tunnel muck. Deposition of tunnel muck in this area would require coordination with the needs of the various construction contractors who would be using it as a staging area. The spoil area could also be extended north of the clearing limits into a 4.6 acre saltwater herbaceous sedge-grass vegetation type east of the access road. This area is presently under tidal influence provided by access road culverts at Sta. 584+20 and Sta. 584+30, respectively. These culverts also provide drainage for a small stream which bisects the sedge-grass lowland. This approximately 200 feet by 1, 000 feet area is bordered to the south by the lower construction camp clearing limits, to the east by the project boundary, to the north by steep, forested hillsides, and to the west by the access road. If brought from about elevation 7 to grade of the access road at elevation 22, the 4. 6 acre area could hold about 111,000 cubic yards of tunnel muck. Drainage for the watershed could be re-routed to parallel and abut the 2-1153-JJ 2-4 steep hillside face on the north side of the sedge-grass lowland. A collecting pool immediately upstream of the access road culverts draining this area could also be provided. A gravel berm separating the tunnel muck from the drainage channel would be placed. Round trip haul distance to the lower construction camp spoil areas would be about 3.4 miles. 2.5 Martin River Borrow Pit Tunnel muck could be hauled and deposited in a Martin River borrow pit. All tunnel muck could potentially be placed in any of the three borrow pits. Round trip haul distance would be about 7.2 miles. Provisions for impact to the mitigation plan for fisheries resources would be required. 2.6 Barge to Homer Excess tunnel muck could be offered for sale and barged to Homer for use as road surfacing or gravel by the Alaska Department of Transportation (DOT) or private firms. Tunnel muck would require stockpiling, loading and trucking to the barge dock, loading on a container or gravel barge, barging to Homer, and then offloading on Homer Spit. Because of the timing of the high tides required to operate a gravel barge at the project barge dock and at the Homer Spit, most hauling would be done in the early fall due to the height and frequency of high tides. To reduce traffic problems within the Homer Port, the barge would be beached on the north side of the Spit and offloaded to a stockpile or waiting trucks. Estimated time to offload the barge is 6 hours. Truck traffic hauling the offloaded tunnel muck from the Spit would require about 20 round trips per hour. This level of truck traffic would impact the heavy recreational use of the Homer Spit during the late summer and fall fishing season. Contractors are 2-1153-JJ 2-5 presently required to minimize traffic on the Spit during the recreational season. A barge load of tunnel muck would be produced about every 3 days. Also, there is some question whether tunnel muck would meet the gradation requirements of local purchasers. The suitability of sale or export of tunnel muck cannot be precisely determined until actual production begins. 2-1153-JJ 2-6 SECT.ION 3 • 0 ENVIRONMENTAL EVALUATION 3.0 ENVIRONMENTAL EVALUATION 3.1 Adjacent to Marshalling Yard The approximately 1.2 acre area between the south face of the marshalling yard and the adjacent embankment is tideland dominated by the saltwater herbaceous sedge-grass vegetation type. The vegetation in this area is the same as in the waterfowl nesting area and lower batch plant. The additional use of sedge-grass tidal flats in the fill area beyond the currently permitted acreage would be about 1.2 acres. If the area was filled with tunnel muck to elevation 30, a limited number of Sitka spruce trees growing along the embankment margin would also require removal. The close proximity of this area to the intensive activities that will take place at the powerhouse and tunnel portal probably make it unsuitable for most wildlife use during the construction period. The area is of relatively small size and is dominated on all sides by either steep, forested embankments or the rock slopes of the marshalling yard. No intertidal ponds occur within this area, and the present level of use by waterfowl is limited. Little use of this area by waterfowl is expected during the operations period. Proximity to the permanent camp and the powerhouse would also discourage use by terrestrial mammals during the operation period. Noise disturbance from trucks hauling tunnel muck would be confined to the powerhouse area for the quantity of fill that could be spoiled in this area. Use of this area as a settling basin for tunnel water would preclude its use as a tunnel muck disposal area. Because of its relatively small size, steep embankments on all sides, and narrow drainage opening, use of this area for either tunnel muck disposal or for settling ponds would not result in substantial disturbance of potential wildlife habitat. 2-1153-JJ 3-1 3.2 Waterfowl Nesting Area Widening of the full 3, 600 feet length of the access road on the waterfowl nesting area side would reduce the size of the waterfowl nesting area by about 4 acres, and bring the northern nesting islands in closer proximity to the access road. Road traffic during the operation period could be maintained on the north part of the road to minimize disturbance to nesting waterfowl. Tunnel muck and fines dredged from tunnel water settling ponds will be used to construct nesting islands, but require covering with dredged silts to promote growth of sedge-grass vegetation. Widening of the 2, 200 feet long section of the access road on the Kachemak Bay side would disturb 2.4 acres of intertidal saltwater herbaceous sedge-grass vegetation and mudflats. One tidal slough would be intersected and a second tidal slough bisected by the widened access road. Dredging to re-route either tidal slough would probably not be necessary. High moisture content tunnel muck would require draining before placement to minimize toe creep. Construction of nesting islands will require careful and specific placement of fill. Placement and construction of nesting islands will be conducted by the rehabilitation contractor near the end of the construction period. Temporary storage of tunnel muck in the 1.25 acre northeast corner of the waterfowl nesting area would provide the source of rock materials necessary for nesting island construction. Placement of tunnel muck in the 1.25 acre temporary storage site would prevent disturbance to sedge-grasses within the waterfowl nesting area before the nesting islands were constructed. 3.3 Northwest Portion of Lower Construction Camp The north end of the construction camp within the staging and topsoil storage areas are already permitted as spoil areas. All spoil would be confined within the existing clearing limits. Perimeter dikes and 2-1 153-JJ 3-2 interceptor ditches would provide for water drainage from the spoil area to a collection point where petroleum products would be removed by sorbent booms. Disposal of tunnel muck within the clearing limits of the lower construction camp would result in no additional impacts. However, extending spoil deposition north of the clearing limits into the sedge-grass lowland would impact approximately 4.6 acres of saltwater sedge-grass vegetation and require clearing of several balsam poplar trees all located east of the existing access road. This area would be protected from wave erosion by the riprap of the access road, and drainage for the tidal slough bisecting this area would be provided by maintenance of drainage connecting the slough with the access road culverts at Sta. 584+20 and Sta. 584+30, respectively. Juvenile salmon have been observed in the existing drainage slough bisecting this lowland. Juvenile salmon would still be able to use the drainage channel adjacent to the hillside. Removal of this saltwater marsh would impact waterfowl habitat provided by the existing saltwater marsh. Rehabilitation of the northwest portion of the lower construction camp would not be impeded by deposition of tunnel muck. Tunnel muck could be covered with a layer of topsoil or gravel after final placement and graded, if necessary. Tunnel muck spoil in this area may provide a firm foundation for contractor laydown and staging. 3.4 Martin River Borrow Pit Deposition of tunnel muck in a Martin River borrow pit would impact mitigation plans designed to create rearing and overwintering habitat for juvenile salmonids. The degree of impact would depend upon the quantity of tunnel muck that would be spoiled. The larger, angular tunnel muck would not provide suitable substrate for salmon spawning or vegetation propagation. Fine tunnel muck could collect in intragravel spaces and reduce upwelling. If tunnel muck 2-1153-JJ 3-3 were spoiled in this area, it would be recommended that a single pit, or portion of a single pit, be designated for spoil to minimize adverse impacts on mitigation plans. Hauling a maximum of 172,600 cubic yards of tunnel muck to a Martin River borrow pit would require approximately 11, 500 round trips of 15 cubic yard dump trucks. Hauling would be intermittent, but would extend through the tunnel excavation period. The haul distance and associated traffic noise would heighten wildlife disturbance along the affected access roads and in the Martin River delta area throughout the construction period. 3.5 Barge to Homer Tunnel muck would require temporary stockpiling on or near the barge dock while awaiting a barge or an appropriately high tide. Work space in the barge dock area is limited, and may require stockpiling in an adjacent area on the tidal flats which would impact waterfowl habitat. The barge would follow the established barge corridor in Kachemak Bay, thereby avoiding impacts to fishermen. 2-1153-JJ 3-4 SECTION 4.0 ECONOMIC EVALUATION 4.0 ECONOMIC EVALUATION The primary expense associated with tunnel muck disposal would be transportation. Approximately 11,500 loads by 15 cubic yard capacity dump trucks would be required to transport a maximum of 172,600 cubic yards from the tunnel portal at the powerhouse to the disposal sites. Unless the lower construction camp or a Martin River borrow pit were used, more than one disposal site would be required. Cost estimates were based on complete utilization of a disposal site up to its maximum capacity or until 172,600 cubic yards of tunnel muck were placed. Where necessary, costs for additional culverts were placed into the estimates. Estimated costs in 1986 dollars are shown in Table 1. Costs for hauling tunnel muck increase with haul distance. The areas adjacent to the marshalling yard and within the waterfowl nesting area were both less expensive than the other options even though they require culvert extensions. However, neither, or even both, of these areas could contain the entire 172,600 cubic yards of tunnel muck expected to be excavated. Quantities exceeding the maximum capacity of these two closer areas would require spoil in another area further away from the powerhouse. Costs for barging tunnel muck to Homer are substantially higher than for disposal on the project site. Discussions with Homer DOT indicate that current state contract bid prices are about $12.00 per cubic yard for pit run gravel hauled from Anchor Point and delivered to their Homer storage yard. DOT concluded that purchase of Bradley Lake tunnel muck would not be economically advantageous. 2-1153-JJ 4-1 TABLE 1 TUNNEL MUCK ECONOMIC EVALUATION Cost ~ 1286 Dollars) Maximum Description Capa3ity (yd ) Hauling3 Cost/yd Hauling Culverts Total Adjacent to Marshalling Yard Tunnel Muck to El. 18 23,000 $ 3.10 $ 71,300 $45,600 $ 116,900 Settling Ponds 14,250 3.10 44' 175 45,600 89,775 Waterfowl Nesting Area Access Road-Nesting Side 88,000 3.10 272,800 32,900 305,700 Access Road-Bay Side 53,600 3.10 166,160 16 ,450 182,610 Northeast Corner & Dike 69,000 3.10 213,900 0 213,900 Lower Construction Camp 172,600 4.15 716,290 0 716,290 Martin River Borrow Pits 172,600 4.70 811,220 0 811,220 Barge to Homer 89,350 25.00 2,233,750 0 2,233,750 SECTION 5.0 RECOMMENDATIONS 5.0 RECOMMENDATIONS The recommended sites for tunnel muck disposal are prioritized as follows: 1. Construction of settling ponds and dikes in the lowland area adjacent to the marshalling yard (1~,250 cubic yards). 2. Temporary storage and dike construction in the waterfowl nesting area for later construction of nesting islands (69,000 cubic yards). 3. Northwest portion of the lower construction camp staging area within the clearing limits (remainder of approximately 89,350 cubic yards). Other identified potential sites would probably not be used for spoil of excess tunnel muck. 2-1153-JJ 5-1 SECTION 6.0 AGENCY CONSULTATION 6.0 AGENCY CONSULTATION August 20 , 19 86 October 23, 1986 December 17, 1986 2-1 153-JJ Source of Correspondence U.S. Department of the Interior, Fish and Wildlife Service, Western Alaska Ecological Services Notes of Conference, Stone & Webster Engineering Corporation Notes of Telephone Conversation, Stone & Webster Engineering Corporation 6-1 r . ... United States Department of the Interior Western Alaska Ecological Services Sunshine Plaza, Suite 2B 411 W. 4th Ave. Anchorage, Alaska 99501 RECEIVED IN REPLY REFER TO: AUG 2 7 1986 WAES . SWEC-ANCHORAGE Mr. David R. Eberle, Manager RECEIVED BY Bradley Lake Hydroelectric Proj~SKA PCYifl~ .~!J'!"H0!:?1TY Alaska Power Authority P. 0. Box 190869 Anchorage, Alaska 99519-0869 Dear Mr. Eberle: Alii 22 A11 :29 Re: Project Airstrip Relocation APA/OTHR/0137 The u.s. Fish and Wildlife Service (F'WS} has reviewed your subject proposal of 15 August 1986. We have no objection to the following items: 1. Deletion of the permanent airstrip from the Fox River Critical Habitat Area. 2. Construction of the permanent airstrip, to be used during the operations phase, along the seaward side of the access road between Sheep Point and the powerhouse. 3. Use of the Martin River delta log and stump storage area as a landing site to support the four-year construction program. 4. Construction and maintenance of a truck turn-around area north of the powerhouse. 5. Construction and maintenance of a marshalling yard adjacent to the tailrace on the south side of the powerhouse. 6. Use of excavated tunnel rock in the construction of the waterfowl nesting islands and for road and yard surfacing. We have no objection to the Alaska Power Authority requesting a modification of the Department of the Army permit from the U.S. Corps of Engineers for the six items listed above. Two items which have not been resolved are: 1. The permanent disposal of tunnel muck in excess of the quantity required for nesting islands and road surfacing. The FWS suggests upland disposal -not on the salt flats. 2. The water encountered during the tunnel boring operation. This water will be carrying rock flour and likely will be contaminated with hydraulic fluid from the tunnel boring machine. The FWS suggests a settling pond with an inverted culvert arrangement to allow the trapping and removal of petroleum products. Thank you for the opportunity to comment. cc: Sincerely, Field Supervisor ADF&G, ADNR, ADEC, DGC -Anchorage CE, NMFS, EPA -Anchorage I . ·-----·-·-· ~~--.: ~·~~~-.. _:~;\C,::; DIS-~. ~-~wi: ~ ~ ·,\..a,c:t·i: _f. /) _ c-c_~~~-.--~-,: --:,; ~·-l :_ s ,;.,(::c_ --~ ,.,_,._ Lsr~J"Lp L11!~L _ _..;;;.. __ I Jtevpr,~ NOTES OF CONFERENCE AGENCY REVIEW MEETING BRADLEY LAKE HYDROELECTRIC PROJECT ALASKA POWER AUTHORITY Held in the Conference Room Stone & Webster Engineering Corporation Boo "A" Street Anchorage, Alaska 99501 October 23, 19 86 9:00 AM PURPOSE Present for: Agencies: J.O. No. 15800.12 WP 98D-6 Patty Bielawski, OMB/DGC Don McKay, ADF&G/Habitat Mark Kuwada, ADF&G/Habitat Pat Beckley, ADNR Deborah Heebner, ADNR Keith Harding, ADNR Hank Hosking, USFWS Scott Hansen, COE Alaska Power Authority (APA) Tom Arminski Dave Trudgen Bechtel Civil, Inc. (Bechtel) John Smith Jim Daly Dames & Moore, Inc. (D&M) Jim Hemming Stone & Webster Engineering Corporation (SWEC) Norm Bishop Bill Steigers The meeting was held to discuss 1) construction of overland access to the Middle Fork diversion site, 2) the Rehabilitation and Recreation Facilities Contract, 3) tunnel muck disposal, and 4) Project Update. The meeting also served as a bimonthly a~ncy update. Attachment 1 is the meeting agenda. Attachment 2 is the sign-in attendance sheet. DISCUSSION Following an introduction by T. Arminski of the general purpose for the meeting, each participant introduced themselves and their affiliation. 2-1173-JJ 1 1. Middle Fork Diversion Overland Access Route J. Smith presented a public relations video tape depicting Bechtel's capability to manage contractors for both large and small projects. Following the video tape, J. Smith discussed Bechtel's methods and capabilities with respect to holding contractors to specific contract requirements. Following this presentation the meeting was opened to discussion relative to the Middle Fork diversion overland access route. H. Hosking requested affirmation that no foreign materials such as gravel would be hauled in during the construction of the Middle Fork overland access, and that no blasting was currently anticipated in construction of the access route. J. Smith confirmed that, at this time, no foreign materials or blasting is anticipated. H. Hosking also inquired how water erosion would be controlled. J. Smith indicated that several measures could be taken to control erosion including grading and dressing the access trail as the equipment was transported back down to Bradley Lake, and cross ditching where necessary to control and divert water that may drain down the trail. When asked of the type of equipment that would be used in construction of the Middle Fork diversion, J. Smith replied that each contractor has different types of equipment. It would be difficult to make an assumption at this time of the exact types and sizes of equipment that would be used. N. Bishop indicated that smaller equipment would be required if helicopters were used to transport equipment. J. Smith also stated that construction of the Middle Fork diversion would require a longer time period if equipment were flown in because of the reduced capabilities of smaller equipment. When asked if any equipment types would be excluded, J. Smith replied that such equipment as wheeled fuel tanker trucks would probably be excluded, but there would be no normal construction equipment that would be expected to be excluded. A Nodwell 240 or equivalent equipped with a fuel tank would probably not be excluded if it were considered that safe passage on the trail was possible for that equipment. A 100 feet wide right-of-way, with a 30 feet wide pathway for the actual trail, was envisioned by J. Smith to be adequate for the overland access route. If the overland access route were adopted, the 100 feet wide right-of-way would be delineated and flagged prior to letting the bid for the Middle Fork diversion. J. Daly stated the two things a contractor wishes to avoid are 1) blasting rock and 2) flowing water because they require extra work which costs extra money. All contractors would visit the site before bidding as a requirement for submitting a bid. Because of a 6 to 8 month period between letting the bid and initiation of construction, the successful bidder would potentially have opportunity to have input on finalization of the route. The contractor may have at his disposal certain equipment that would make a certain access route preferable over an alternate access route. The restricted 100 feet wide right-of-way would eliminate arbitrary starts selected by the contractor. Within the 100 feet wide i::::-1 173-JJ 2 corridor, the contractor could select his own route to the Middle Fork diversion site. Once that route were selected, the contractor would be required to stay within the 30 feet wide initial pathway created by the leading equipment. The contractor will be required to utilize the route according to restrictive specifications. The Alaska Power Authority EFO and Bechtel would be jointly responsible for enforcing the contractor's compliance with environmental and contract specifications. In responding to a question from P. Beckley in reference to the differences in ground pressure be tween a D6 and D8 tractors, J. Smith indicated that there was no real differences in effective ground pressures between the two tractors but the D8 had a wider thread width and could be equipped with a wider blade. A 08 with a narrow blade would probably be an advantage during construction of the actual Middle Fork diversion. When asked about the expected number of days that would be required to complete the access route and move equipment to the site, J. Smith replied that it was difficult to estimate, but probably would be completed within a 7 day period. N. Bishop suggested that a limitation in the size of barge that could be brought up the project access road to the dam site would be a factor limiting the size and number of pieces of equipment that could be moved from the dam site across Bradley Lake to the beginning point of the access trail. Workers would be flown in daily from the project construction camp to the Middle Fork diversion site. A spring or early summer construction start would be essential because of weather limitations during late fall and winter. It was stated that a known migration corridor of mountain goats between s1.111mer and winter range crossed the proposed access route. This was discussed, but generally concluded that the level of disturbance created by passing traffic on a one time travel in and out would generally not cause significant disturbance to migrating mountain goats. It is expected the contractor will have completed the Middle Fork diversion construction and demobilized from the Bradley Lake area by the em of the summer prior to goat migration to winter range. A mid to late summer initiation of construction would probably not give the contractor sufficient time to complete the construction in one summer. Severe winter and snow conditions at the Middle Fork site would probably preclude construction during late fall and winter. Weather conditions necessitate early summer start-up of construction. N. Bishop indicated the hillsides above Bradley Lake were dominated by colluvial gravels and exposed rock in most areas, making them a rather stable substrate for equipment in early summer. When questioned about the probable approach that equipment operators would take when encountering wet or boggy areas, J. Smith indicated that deep, wet layers would not be pushed out but rather mats or geotextiles would be laid down and the equipment walked over those materials. It is expensive to move materials, and the contractor will take all reasonable measures available to him rather than moving large 2-1173-JJ 3 quantities of material. There was same discussion about the nature of wet or boggy soils that might be encountered along the access route. Crawler tractors can sidehill effectively, and in many cases could skirt wet or boggy areas. The project access road from Kachemak Bay to the Bradley Lake dam site is strong evidence that a pioneer trail from Bradley Lake to the Middle Fork diversion site can be engineered to address environmental. concerns and minimize disturbance. Where the access trail passes through alders, they would probably be hand cut to ground level where necessary. D. Heebner stated that alders revegetate quickly when cut at ground level. Alders naturally re-sprout from remaining root systems. The presence of roots would also assist equipment traveling over those areas. s. Hansen stated that it would be difficult or nearly impossible to prevent tracks of equipment fran spinning. He also stated the growing season was short and because revegetation could not proceed until the following year, erosion would occur in the interim. T. Arminski indicated that erosion control matting would be used in steep areas and diversion berms or diversion logs placed every 30 feet may be used to control erosion until the following year. When asked of the number of pieces of equipment that would be moved to the diversion site, J. Smith stated that up to 20 pieces of equipment on tracks, wheels, or skids would be moved along the access trail in each direction. B. Steigers discussed opportunities for rehabilitation and revegetation of the access trail. The trail would be dressed by the final pieces of equipment coming out on the access trail. Dressing would entail smoothing to eliminate ruts and cross ditching every 30 to 50 feet to control runoff down the trail. Cross ditching would entail an angled 8 inch berm, which would create a ditch 15 inches deep on the uphill side of the berm. Revegetation would include broadcast seeding of a grass-forb mixture on slopes of shallow-to-moderate slope. On steeper slopes, erosion control blankets would be used. Bundle planting of rooted shrubs on slopes may also be used in areas of high erosion potential. Samples of erosion control blankets were distributed and a discussion followed on how erosion control blankets could be laid down on steep areas following movement of the equipment into the site. These blankets would remain in place when the equipment came back out, and other blankets again laid down after the equipment had passed. S. Hansen stated that the methods used to control erosion and promote revegetation would be very important to the resource agencies. Resource agencies were assured the Power Authority would take all necessary precautions and measures required to minimize erosion and to promote rapid revegetation. When asked if erosion control blankets would be used over the entire route, B. Steigers replied that erosion control blankets would be placed where necessary on steeper slopes and that other methods such as scattering of straw or contouring and seeding would also be used. Several types of erosion control blankets are available, and the particular type of blanket used would be matched 2-1173-JJ 4 to the specific requirement. If seeding is undertaken prior to placement of the erosion control blankets, the blankets will hold the seed in place through the winter until the following growing season. N. Bishop reiterated that approximately $500,000 would be saved by establishing an overland access trail to the Middle Fork diversion site. The greater safety of overland access over helicopter transport of equipment, and decreased time for construction because of the larger equipment that can be taken overland than by helicopter transport are also considerations. s. Hansen stated that this area is above headwaters. Normally, if no cut and fill resulting in changes to contour lines were required this work would fall under the Nationwide Corps Permit. If significant cut and fill which would change contours were needed, an individual permit would be required under normal circumstances. However, because this activity is part of the Bradley Lake project, it will need to be addressed in the individual permit which already exists for the project. N. Bishop indicated that following the route survey and probes to determine soil types and depth, the quantities and locations of disturbance would be better known. Agency representatives were then asked to provide their general impressions of the overland access concept. D. McKay indicated that surface disturbance could not be avoided and rehabilitation measures would be necessary if the overland access were established. Creation of roads generally caused management problems for ADF&G or secondary impacts on animal populations. An unknown number of hunting permits are issued for mountain goat in this area. Construction of an overland access trail to the higher elevation areas from Bradley Lake would result in some impact on success rates of mountain goat hunters in this unit, and ADF&G would potentially have to revise the number of permits issued or adjust other management options to account for increased access. B. Steigers commented that minimal impacts would be realized by ADF&G managers of area goat populations because of the small number of animals under consideration. B. Steigers felt management implications of reducing number of permits from approximately 8 to 6 should be kept in perspective. P. Beckley thought the overland access to be feasible, but suggested the Power Authority look at alternate beaching sites along Bradley Lake. He sug~sted the contractor avoid all wet and boggy areas to the extent feasible. There was a discussion of the advantages of the various equipment and equipment sizes. P. Beckley felt the D6 was more maneuverable than the D8. N. Bishop stated that the larger tractors were more suitable for ripping. The difference in track width between a D6 and D10 was said to be approximately 1 foot. J. Daly stated that larger pieces of equipment were more economical to operate, and that blade sizes could be limited on the larger equipment to narrow their effective width over the overland trail. Wider tracks could be required for travel on the overland trail, even though the contractor may elect to use narrower tracks while ripping. When asked of the 2-1173-JJ 5 types of equipment that would be transported over the trail, J. Smith listed a backhoe, loader, D8 or D9 for ripping, drills, compressors on skids or wheels, and miscellaneous equipment that would be transported in sane type of container. Other types of equipment and supplies required at the Middle Fork diversion site would be crew survival sheds, small generators, and a fuel facility. N. Bishop reiterated that it is the Power Authority's desire to keep construction costs of the Middle Fork diversion as low as possible. However, the Power Authority is willing and is ccmmitted to minimizing environmental impacts wherever practicable and will mitigate for unavoidable impacts. T. Arminski summarized this portion of the meeting by stating that a decision-making document would be prepared which would describe the proposed action and alternatives and would address those concerns brought up by agency representatives at this meeting. This document would be sent out for review and ccmment by the a~ncies and would be the basis for deciding on how to proceed with the overland access alternative. It was agreed that this document would also address methods and costs for rehabilitation, erosion control", and revegetation. This document would contain as an attachment the notes of conference for this meeting. All feasible routes of access would also be explored. This document would be distributed during December 1986. 2. Rehabilitation and Recreational Facilities Contract The Power Authority is considering the expansion of its present 10 contract scenario for the development of the Bradley Lake Hydroelectric Project to include a rehabilitation and recreational facilities contract as an 11th contract. The reasons for this expansion are to: 1) provide further opportunity for local contractor participation; 2) minimize potential construction contractor conflicts; 3) achieve a better rehabilitation end product; and 4) reduce potential risk for construction claims. N. Bishop discussed the scope of work for the new rehabilitation and recreational facility contract. 1. Rehabilitation of the Martin River borrow areas 2. Rehabilitation of and/or removal of the Martin River borrow access road. 3. Construction of the waterfowl nesting islands. 4. Construction of recreation facilities. 5. Rehabilitation of miscellaneous areas, including fertili- zation and reve~tation of: a. Staging and laydown b. Disposal areas c. Concrete batching areas d. Quarry sites e. Disturbed areas adjacent to access roads f. Culvert and road maintenance 6. Rehabilitation of the construction camps. 1. Revegetation activities. 8. Other undefined miscellaneous items. 2-1173-JJ 6 This contract is expected to conclude one year (1 spring) after completion of the General Civil Contract. Following completion of this contract, the operations and maintenance of the Bradley Lake project would be turned over to the managing entity. The bid document would prepared during 1988 and the bid let during mid-1989. Agency representatives had no comment on the rehabilitation and recreational facility contract. 3. Tunnel Muck Disposal N. Bishop discussed the need for identifying a tunnel muck disposal area as a result of relocating the permanent project airstrip. Tunnel muck is described as angular clean, poorly graded rock material ranging in size fran sand to rock 1 to 3 feet in diameter. Rock produced by blasting is usually larger than that produced by the tunnel boring machine (TBM). J. Daly described tunnel muck produced by older TBM's as angular rock ranging in size from sand particles to 2 1/2 inches. Tunnel muck from newer TBM's usually ranges in size from sand particles to 1 1/2 inches in diameter. If the rock is sound, the tunnel muck produced by a TBM usually makes a good road surfacing material. If the rock is not sound or has an affinity for water and does not drain easily, the resulting product is very fluid until the water has been drained. If drained, sane of this material could be stockpiled for road maintenance purposes. J. Hemming suggested that some of the tunnel muck could be offered for sale and barged to Hamer to be used for road surfacing or gravel. On site investigations have resulted in identification of several possible disposal sites for the tunnel muck. The possible disposal sites are: 1. Adjacent to the marshalling yard; 2. In the waterfowl nesting area adjacent to the access road; 3. In the lower concrete hatching area and clean fill disposal sites; 4. Northwest portion of the lower construction camp staging area; 5. Martin River borrow pit; and 6. Other unidentified areas. The advantages and disadvantages of each potential disposal site were discussed. 1. Adjacent to Marshalling Yard. 2-1 173-JJ An area approximately 160 feet wide and 320 feet long (about 1 .2 acres) between the marshalling yard and the shoreline north of the permanent camp could be used as a disposal site for tunnel muck. Approximately 23,000 cubic yards of tunnel muck could be deposited in this area if it was brought to the elevation of the marshalling yard at elevation 18 feet. 7 Alternatively, up to 65,000 cubic yards could be deposited if both the marshalling yard and adjacent area were filled to elevation 30 feet. The latter fill depth would bring the fill to the elevation of the adjacent permanent camp area, but would infringe upon use of the marshalling yard for its intended purpose as a service area for the tunnel portal. This area will be used as a settling pond, with a small dike constructed between the northwest corner of the marshalling yard and the adjacent embankment. 2. Waterfowl Nesting Area Adjacent to Access Road Widening by an additional 47 feet the 3,600 feet long access road adjacent to the waterfowl nesting area would provide disposal for approximately 88,000 cubic yards of tunnel muck. Widening of the access road would require lengthening of ten 48 inch diameter culverts by 47 feet and relocation of 10 concrete drop boxes. This scheme would reduce the size of the waterfowl nesting area by about 4 acres and bring the northern nesting islands in closer proximity to the access road. If a larger area were desired the western or eastern corners would provide additional storage area for tunnel muck. 3. Lower Concrete Batching Area and Clean Fill Disposal Sites These areas are expected to be filled prior to initiation of power tunnel construction. 4. Northwest Portion of Lower Construction Camp 2-1173-J J The northwest portion of the lower construction camp is presently being used as a log storage area. Ultimately this area will be used for contractor staging and laydown. The present design calls for the 10 acre northwest staging area to be brought up to grade at elevation 12 feet with Martin River fill to raise it above the maximum high tide elevation of 11.4 feet. This area has excellent potential as a disposal site for tunnel muck. The area within the clearing limits of the lower construction camp boundary in the northwest staging area could contain 193,000 cubic yards of tunnel muck at elevation 22 feet. Elevation 22 feet is the design elevation of the adjacent access road. Deposition of tunnel muck in this area would require coordination with the needs of the various construction contractors who would potentially use it as a staging area. A gravel berm could be maintained at the northern clearing limits to contain tunnel muck within the designated spoil area. 8 The construction camp spoil area could be extended north of the clearing limits into a 4. 6 acre saltwater herbaceous sedge-grass vegetation type behind the access road. This area is presently under tidal influence provided by double culverts on the access road. This approximately 200 feet by 1000 feet area is bordered to the south by the lower construction camp clearing limits. If brought to grade of the access road at elevation 22 feet from about 7 feet elevation, the 4. 6 acre area could hold 111,000 cubic yards of tunnel muc·k. Drainage for the watershed would be re-routed to parallel and abut the steep hillside face on the north side of the sedge-grass lowland. D. Trudgen stated that juvenile salmon had been observed in this drainage slough. H. Hosking indicated his opposition to encroachment beyond the clearing limits into this wetland and further re-routing of this slough channel. 5. Martin River Borrow Pit All tunnel rock could potentially be placed in any one of the borrow pits. Deposition of tunnel muck in the Martin River borrow pits would impact mitigation plans designed to create rearing and over-wintering habitat for juvenile salmonids. The degree of impact would depend on the quantity of tunnel muck that would be spoiled in the pits. D. Trudgen recommended that if tunnel muck were placed in the Martin River pits, that it be placed in a corner of one of the downstream pits. Tunnel muck would be covered by Martin River spoils following completion of hauling. It was stated that trucks hauling muck could not backhaul Martin River gravels to the concrete ba tching plants because the concrete aggregate would be contaminated. Additionally, sequencing of the con tracts would not provide an opportunity for backhauling. 6. Other Unidentified Areas Agency representatives did not have any further recommendations for additional tunnel muck disposal areas. When asked for responses to the suggested alternative disposal sites, H. Hosking recommended investigation of barging some of the tunnel muck to Homer. D. McKay indicated his opposition to spoiling tunnel muck in the Waterfowl Nesting Area. H. Hosking stated his opposition to storage or placement of tunnel muck on the tidelands. There was some discussion of extending the dock area to the east or west but this was opposed by ADF&G and USFWS. P. Beckley stated his preference for use of the area beside the marshalling yard, but it was stated that this was a relatively small area and would preferably be used as a settling basin for tunnel water. 2-1 173-jJ 9 It was agreed that up to 65,000 cubic yards (or the required amount) of tunnel muck could be stored in the Waterfowl Nesting Area for use in construction of the nesting islands. The tunnel muck would be placed by end dumping in a series of roads within the Waterfowl Nesting Area or in one corner of the nesting area in preparation for construction of the nesting islands. It was agreed that tunnel muck would be disposed of as follows: 1. In the construction of dikes adjacent to the marshalling yard to create settling ponds for tunnel water. 2. Up to 65,000 cubic yards in the Waterfowl Nesting Area for construction of nesting islands. 3. The lower construction camp staging area within the clearing limits. 4. Project Update. The Power Authority will apply for a NPDES permit for the tunnel water. Preparation of the 1986 fisheries monitoring study report by Dames & Moore will be complete by the end of October. A report on the 1986 Bald Eagle Program will be prepared and distributed by mid-November. The well arilling equipment on the project site has been demobilized. It is believed that enough water is now available frau the wells and other sources for the permanent camp facilities. The Power Authority is investigating utilizing water from Powerhouse Creek for the concrete batching water to facilitate other water sources available for that purpose. ACTION A decision-making docunent for the Middle Fork overland access route and an assessment of tunnel muck disposal areas will be prepared and distributed to resource agencies for their review and comment. B. Steigers WDS/JJ 2-, 173-J J 10 2-115::>-JJ AGENDA AGENCY REVIEW MEETING OCTOBER 23, 1986 Held at Stone & Webster Engineering Corporation Boo "A" Street Anchorage, Alaska Introduction -Tom Arminski Middle Fork Overland-Access ConstrUction Access -John Smith Revegetation/Rehabilitation -Bill Steigers Economic Benefits -Norm Bishop Rehabilitation Contract -Norm Bishop Tunnel Muck Disposal -Norm Bishop If -tf4ch men+ 2 ~'4'1or /Jv1M Jlkhj ... . .&.11 S7-ei1er-.s S1j,V} -up Sk+ llo~+ NoteM. 8t ~WoP /?If fieMws-f.· d)lvt..'7'~~ z;l;a( /JI~t?HI/tf t0ox ~ 'f., f.A w~ J)_,~JA ~\~ Kerr4/-l"'nt; \:::;.""'-M t. \Z01 y ~ -flam J;sk,· -T P.O.#/}/ /-t, tYK Its jC; N LT Toh# E: S""',77 fbf 8ec~ley Sco it Hansen Sw~L Al?6-C. 1114 fom'<7s/Jflutlr6 Ao~c-q fl"DNR /ID!Uf( ~ v r ~r c., I \ ~k)IL_( APA f3ea-AI-~I r-v.J S f3EC#Ji=£ A-D!UK Co£ ~le;knu :; 77-:J'f :J. 7 J 7?-:;2'-/)7 .27Y-!S?I 236-~~~ 5tl--33h6 U7-Z-2-&S l Co ..J. -).).-IC\' 7£>Z--2Z7tf d-71-t!S'IS 2 35-6001 7~2-22 7'1 ~ 75 3 -;J 71 2_ vJft J.O. No. 15500 & 15800 NOTES OF TELEPHONE CONVERSATION BRADLEY LAKE HYDROELECTRIC PROJECT Alaska Power Authority Sheet 1 of _1_ File No. 15800.12 ( WP 98D--6) SUBJECT Transportation of Tunnel Muck by Barge from Homer INSTRUCTIONS: Summarize your phone discussion, noting participants, date & time of call. Indicate desired distribution at right. Call reporter must insert File Number<Sf and Subject(s) in file box above. Clerk takes care of Chrono file copy and distribution. 2 E. Puch 1 M. Fisk J. Finn! more 1 DISTRIBUTION: JJMPlante/DLMatchett DOC GF 1 --'---JJGarrity/Chron Files 1 --'----T Critikos JBK TK 1£ WP 98D _..:,.1 __ DPRyan 1 NABishop --'-,-- LCDuncan 1 CLClark --'-1 -- JHron GEEng MMiddaugh WCSherman JBYale RKrohn JNowak JNowak T1.4 Call Date _..:.:12=--....:1_._7_-8::.:6=---Time 11:45 a.m. Incoming __ Outgoing --=x=--- Between ____ :B:il~l~S~t~e~i~s~e~r~s _______ SWEC & -----------------------------APA -------------------SWEC & --------------------- & Randel Jones ( 907) 235-5217 Originated by : -=::;B=i=-1 ::.l....:S:.:t::..;e::.::i::..'lis;l.;:e:.:.r-=s:.-________ __ ( ) ( DOT ) Homer DISCUSSION: Randel Jones is Highway Maintenance Foreman for the Alaska Department of Transportation in Homer and is responsible for ordering pit run gravel for highway maintenance in the Homer area. Mr. Jones said the pit run gravel they need is purchased out of Anchor Point. Prices paid are based on contractor bids to the state. Mr. Jones gave three recent bids for pit run gravel per cubic yard delivered to their Homer storage yard: $12.37 per cubic yard; $12.03 per cubic yard; $11.10 per cubic yard. Estimated costs for transporting tunnel muck from the tunnel portal by gravel barge to the end of Homer Spit is $25.00 per cubic yard. The tunnel muck would require transport at additional cost from Homer Spit about 10 miles to the DOT Homer storage yard. Based on these cost estimated, Mr. Jones determined that purchase of tunnel muck would not be to the economic advantage of DOT, and that they would probably not be interested. ACTION REQUIRED: Incorporate information into Tunnel Muck Assessment. 1-479-JW