L - Alaska Energy Data Inventory

Thirteen test pits and trenches were dug in the fan area by Bureauof Reclamation personnel in 1957. About 1,300 pounds of minus 3-inchmaterial was tested by the USBR for basic aggregate suitability studies.An additional 200 pounds of material was collected by Corps of Engineerspersonnel in 1975 from the existing Bureau test pits and the riverbank.This material was tested by the North Pacific Division Materials Laboratoryin 1978 .If the excavation of materials is confined to that part of thealluvium located above river level (elevation 910 to 920 feet) withconservative back slopes through the ridges and benches, approximately6,000,000 cubic yards of material is available in this location withall the resulting excavation in the reservoir area. Seismic refractionsurveys indicate that usable gravel exists to approximately elevation870 feet, so additional material could be retrieved if needed by bailingfrom below the water surface. Placement of the coffer dam, sizing ofthe diversion tunnel, and the ability to control the flow in the riverat Watana dam will ultimately affect the method of exploitation of thissource.The locations of the test pits are shown on Plate D-l and the~etailed logs can be found in the U.S. Bureau of Reclamation's AlaskaGeologic Report #7, Devil Canyon Project, dated March 1960. Laboratoryinvestigations of the aggregate samples were reported in USBR Report#C-932 by their Concrete Laboratory Branch, dated 21 December 1959.Petrographic analyses of the fine (sand sized) particles and coarse(gravel size) particles indicate that the sands and gravels in the fanare composed of quartz diorites, diorites, granites, andesites, dacites,metavolcanic rocks, aplites, breccias, schists, phyllites, argillites,and amphibolites. The gravel particles are stream worn and generallyrounded in shape. The sand grains vary from nearly rounded to sharplyangular in shape, averaging subangular. The specific gravity (BSSD) ofthe material ranges from 2.68 to 2.80.Results from both labs indicate that the materiai in the CheechakoCreek fan is of adequate quality for use as concrete aggregate.Embankment Material ReguirementsThe saddle dam on the left abutment, associated with the concretegravity dam, will require approximately 835,000 cubic yards of material.These materials will be obtained from the same sources as discussed inthe Interim Feasibility Report.D-ll