Dot.alaska.gov



Kiana Airport Improvements ProjectPrecursory Bedrock Mapping and Sampling ProgramState Project No. Z631790000September 11, 2017 photograph showing two members of the project team, Kiana residents Pete Wilson (left) and Bobby Atoruk (right), marking the trail that leads to the subject property, the unnamed hill in the background of this photograph.Report prepared by William M. Kulash, Environmental Impact AnalystAlaska Department of Transportation and Public Facilities, Northern RegionNovember 9, 2017PROJECT LOCATIONThe project site is located on the eastern side of an unnamed hill that’s located approximately 2.8 miles northwest of the City of Kiana and adjacent to the NANA Regional Corporation’s (NANA) proposed gravel quarry, Material Site A-1. The program was completed within:Section 31, Township 19 North, Range 8 West, Kateel River Meridian, USGS Quad map Baird Mountains A-4;Section 36, Township 19 North, Range 9 West, Kateel River Meridian, USGS Quad map Baird Mountains A-4; Section 6, Township 18 North, Range 8 West, Kateel River Meridian, USGS Quad map Selawik D-4Figure 1 is provided as the Location and Vicinity Map and is included in Appendix A.PROJECT OBJECTIVEThe project objective was to collect representative samples of the underlying bedrock on the eastern side of the unnamed hill that’s adjacent to NANA’s proposed gravel quarry. The samples collected were submitted for laboratory analysis to determine if the rocks meet standard airport material specifications. The reason was to help ensure that there’s a viable material source available should the proposed gravel quarry be unable to produce gravels that meet material specifications for crushed aggregate surface course; approximately 30,000 cubic yards of this type of material will be required for the Kiana Airport Improvements project. METHODOLOGYOn August 25, 2017, NANA granted permission to the Alaska Department of Transportation and Public Facilities (DOT&PF) to enter upon NANA lands for the purpose of completing a precursory bedrock mapping and sampling program (Appendix D). The methodology used to complete this program is described below:A sampling grid was established in order to have a systematic approach for plotting the data collected and to have survey control while in the field. The sampling grid was established using a Brunton? Pocket Transit (Brunton compass) and hip chain measuring device, calibrated in feet. Survey flagging was hung in the branches of the trees to mark the linear lines of the sampling grid. Prior to establishing the sampling grid the project geologist (Bill Kulash) used the National Oceanic and Atmospheric Administrations’ Magnetic Field Calculator to determine the latest magnetic declination for Kiana, determined on September 6, 2017 to be 12.67° East (Appendix E). The Brunton compass was then set to this declination so that the grid lines are orientated to the azimuth of true north, versus magnetic north. The test pit locations were spaced along the sampling grid lines (prospect lines) at intervals of every 400 feet. However, flexibility as to where the actual locations of the test pits were dug were given considerations of vegetative cover (trying to avoid digging through dense root mats) and topography features, which included not digging test pits in drainage areas when possible. A handheld GPS, Garmin model GPSMAP-60CSx, was used to record the latitude and longitude of each test pit location. Each test pit was marked with a 3-foot tall survey lath that had its respective coordinates written on it. The test pits were dug by hand using picks and shovels. Test pits were not dug any deeper than 4 feet due to limitations of what can be reasonably dug by hand in a reasonable amount of time. The geologic information obtained from each test pit was recorded in the field notes (Appendix E). There were six rock samples collected for laboratory analysis during this program. Each sample weighed approximately 50-pounds. The exploration crew carried these samples back to the location where the 4-wheelers were parked and then transported them back to Kiana for shipment to the DOT&PF Northern Region’s materials testing laboratory. The starting point for the prospect lines was selected, in part, because: (1) There was an existing trail and favorable topography that allowed the project team to safely use 4-wheelers to access an area that was close to the base of the project hill, which was also close to the starting point; (2) Since there was no previous information available on what the underlying bedrock is, it was reasonable to dig a test pit at first favorable location.No hydrochloric acid (HCl) was brought to Kiana to field test for the presence of calcium carbonate (CaCO3) in the rocks because of airline cargo restrictions that prevents the transport of acids. Only the samples collected during this program were test for presence of CaCO3 and only after they arrived at DOT&PF’s materials testing lab.FIELD OBSERVATIONSThere were no bedrock outcrops encountered along either of the prospect lines, nor did any of the test pits have bedrock exposures that would allow for the measurements of the strike and dip of the bedding. Figure 2 in Appendix A depicts the locations of the prospect lines and test pit locations.South Prospect LineStation 0 South / 0 West (this is the starting point for both the south and west prospect lines)67.00115° N, 160.51201° W0 → 8” organics8” → 2.5’ grey colluvium consisting of buff colored fine grained sandstone & quartz mica schist (QMS) mixed in with silty organic soil; thawed, moist2.5’ → 4’ reddish grey weathered QMSThe rock does not effervesce in HCl, e.g. no CaCO3Sample #1 was taken from this locationStation 400 South / 0 West67.00003° N, 160.51196° WTalus outcrop consisting of reddish grey QMS; the schist has coarse grained muscovite micas with minor amounts of fine grained sericite. Station 800 South / 0 West66.99891° N, 160.51210° W0 → 6” organics6” → 2.0’ colluvium composed of QMS, a few pieces of milky qtz. ≈ + 3 inches diameter, angular with moderate iron oxide (FeOx) staining, no visible sulfides2.0’ → 2.5’ weathered bedrock, reddish brown QMS, thawed, moistStation 1,125 South / 0 West66.99810° N, 160.51233° W0 → 6” organics6” → 2.5’ colluvium, thawed, moist. Within the colluvium at this site was one large oblong shaped boulder that’s been rounded by stream action. This boulder is interpreted to be a glacial erratic and is discussed in detail under the heading of Hypotheses. 2.5’ → 3.5’ bedrock, buff colored metasandstone/quartzite with minor amounts of fine grained sericite. This rock is blockier and has more of a quartzite texture than other metasandstone observed. The rock’s primary bedding is still preserved. Station 1,200 South / 0 West66.99770° N, 160.51219° W0 → 2.0’ well developed organic soil; there are some large spruce trees (≈18” dia.) growing amongst the alder in this area.2.0’ weathered bedrock; the rock type is not readily discernible, it appears to be a dolomitic marble whose features are altered by the partial recrystallization of its matrix. The rock is a blackish grey color with small angular breccia clasts cemented by calcite. There are small vugs that with euhedral quartz and calcite crystals. There are also small discontinuous calcite and milky quartz veins. The rock has strong manganese oxide staining along its fractures. Additionally, there is one fine-grained milky quartz veins, ≈1 inch thick with weak FeOx staining, that has a thin laminae of sandstone attached. In the field, this test pit is interpreted to be located at or near the contact between the sandstone and dolomite. There were no visible sulfides in any of the vein material or the rock. Photographs of this rock type are provided in Appendix C of this report.Sample #2 was taken from this locationStation 1,300 South / 0 West66.99751° N, 160.51222° W0 → 6” organics6” → 1.5’ colluvium, thawed1.5’ → 2.5’bedrock, QMS, siliceous, some pieces of milky quartz < ? inch thick, weak to moderate FeOx staining, no visible sulfidesStation 1,400 South / 0 West66.99721° N, 160.512227° W0 → 2.0’ frozen organic soil; left this test pit to sit overnight to thaw. Returned the next day (Sept. 13, 2017) and the test pit was still frozen and completely filled with water; did not advance the pit any deeper; bedrock was not encountered. Station 1,800 South / 0 West66.99598° N, 160.51233° W0 → 8” moss8” → 2.5’ organic soil; frozen, ice lenses with some exceeding 2-inches thick; no rocks were encountered.Station 2,050 South / 0 West66.99534° N, 160.51274° W0 → 1.0’ organics with pieces of wood1.0’ → 2.5’ organic soil, thawed, moist2.5’ → 3.0’ weathered brownish grey QMS, weak FeOx staining, no CaCO3, no visible sulfides Sample #3 was taken from this location Station 2,200 South / 0 West66.99488° N, 160.51236° W0 → 6” organic mat6” → 2.0’ colluvium, thawed, moist2.0’ → 3.0’weathered bedrock, QMS; moderate FeOx staining on the weathered surfaces3.0’ → 3.5’ bedrock became more competent; reddish grey QMS, coarse grained muscovite micas, not as siliceous as some of the QMS observed along this prospect line, although there are some small interbedded layers that are siliceous; no visible sulfidesStation 2,600 South / 0 West66.99380° N, 160.51270° W0 → 4” organic mat4” → 2.5’ colluvium, thawed, moist3.0’ → 3.5’ bedrock, whitish tan, thinly laminated fine grained sandstoneSample #4 was taken from this locationStation 2,800 South / 0 West66.99313° N, 160.51283° W0 → 6” organic mat6” → 4.0’ colluvium, thawed, moist; did not reach bedrock in this test pit. The colluvium contains both QMS (≈ 60%) and sandstone (≈ 40%) with small amount of milky quartz, ≈ 2” thick vein material. No visible sulfides.End of South Prospect Line (Station 2,800 South / 0 West)West Prospect LineStation 0 South / 400 West (this station is 400 feet west from starting point, Station 0 South / 0 West)67.00117° N, 160.51489° WTalus, composed of QMS, tried digging through this accumulation of rocks but was only able to advance ≈ 2’.Station 0 South / 800 West67.00118° N, 160.51767° W0 → 4” organic mat4” → 2.5’ colluvium, grey micaceous silty clay, thawed2.5’ → 2.5’ still colluvium but this horizon is predominately QMS, water draining through this horizon is quickly filling the test pit.Station 0 South / 1,200 West67.00110° N, 160.52030° W0 → 4” organic mat4” → 4.0’ colluvium, thawed, moist. The colluvium consisted of reddish grey QMS, white sandstone, and pieces of bull quartz. Weak FeOx staining of the colluvium occurred at the depth of ≈ 3.5’, bedrock was not encountered. Station 0 South / 1,600 West67.00098° N, 160.52312° W0 → 4” organic mat4” → 4.0’ colluvium, consisting of grey QMS and pieces of bull quartz, thawed, moistStation 0 South / 2,000 West67.00081° N, 160.52574° W0 → 6” organic mat6” → 3.0’ colluvium/talus, thawed, moist. The talus consisted of grey QMS. Station 0 South / 2,400 West67.00063° N, 160.52898° W0 → 2” organic mat2” → 8” organic soil, thawed, moist.8” → 3.0’ talus, consisting of large pieces of grey QMSStation 0 South / 2,800 West67.00055° N, 160.53198° W0 → 4” organic mat4” → 3.0’ colluvium, thawed, moist. The majority of the colluvium is composed of a hard blackish grey metasandstone that’s broken along its bedding planes into slabs that are ≈ 2-4 inch thick. The colluvium also has large pieces of QMS and large pieces of angular bull quartz; one piece of bull quartz extracted from this test pit was as large as a basketball. Sample #5 and Sample #6 were collected from this same location because the rocks within the talus were fairly representative of what had been encountered along this prospect line. Sample #5 was one large piece of grey QMS, it effervesced weakly in HCL. Sample #6 was the metasandstone, it strongly effervesced in HCL. Station 0 South / 3,140 West67.00030° N, 160.53418° W0 → 6” organic mat6” → 3.0’ colluvium/talus, thawed, moist. The colluvium is predominately QMS with large pieces of angular bull quartz.End of West Prospect Line (Station 0 South / 3,140 West)LABORATORY RESULTSThere were six rock samples collected in the field during this exploration program. These samples were submitted to DOT&PF’s Northern Region materials testing laboratory on September 22, 2017 for the following analyses: Degradation Value; L.A. Abrasion; Sodium Sulfate Loss, Specific Gravity, and; NORDIC Abrasion. The laboratory results of these analyses are provided in Appendix B and are summarized in the tables below:Sample #1Rock type: quartz mica schistStation 0 South / 0 WestAnalysisResultStandard Airport Material Specificationsfor Aggregate Surface CourseDegradation Value33>45L.A. Abrasion35<50Sodium Sulfate Loss0<12Specific Gravity2.779≥ 2.65 for riprap materialNORDIC Abrasion48.10No standard; in general ≤ 35 is sufficientSample #2 Rock type: dolomitic marbleAnalysisResultStandard Airport Material Specificationsfor Aggregate Surface CourseDegradation Value40>45L.A. Abrasion41<50Sodium Sulfate Loss2<12Specific Gravity2.703≥ 2.65 for riprap materialNORDIC Abrasion42.30No standard; in general ≤ 35 is sufficientSample #3 Rock type: quartz mica schistAnalysisResultStandard Airport Material Specificationsfor Aggregate Surface CourseDegradation Value33>45L.A. Abrasion33<50Sodium Sulfate Loss1<12Specific Gravity2.795≥ 2.65 for riprap materialNORDIC AbrasionNot enough sampleNo standard; in general ≤ 35 is sufficientSample #4 Rock type: metasandstoneAnalysisResultStandard Airport Material Specificationsfor Aggregate Surface CourseDegradation Value22>45L.A. Abrasion54<50Sodium Sulfate Loss0<12Specific Gravity2.734≥ 2.65 for riprap materialNORDIC Abrasion33.70No standard; in general ≤ 35 is sufficientSample #5 Rock type: quartz mica schist (talus)AnalysisResultStandard Airport Material Specificationsfor Aggregate Surface CourseDegradation Value30>45L.A. Abrasion39<50Sodium Sulfate Loss1<12Specific Gravity2.786≥ 2.65 for riprap materialNORDIC Abrasion57.90No standard; in general ≤ 35% is sufficientSample #6 Rock type: metasandstone (talus)AnalysisResultStandard Airport Material Specificationsfor Aggregate Surface CourseDegradation Value27>45L.A. Abrasion71<50Sodium Sulfate Loss1<12Specific Gravity2.722≥ 2.65 for riprap material NORDIC Abrasion75.10No standard; in general ≤ 35 is sufficientHYPOTHESESBedrock is potentially more competent at depthThe project team was only able to sample the top surface of the weathered bedrock. As such, it’s reasonable to infer that the bedrock is likely to become more competent at depth, below the weathered (degraded) surfaces.TalusThe talus accumulated along the hill’s slopes may be a viable material resource. Observations of the talus encountered along the two prospect lines indicated that at these locations, the talus is composed primarily of large angular pieces of QMS. There were also large tabular pieces of metasandstone incorporated into the talus at many locations, but to a lesser extent than the QMS. Based on field observations of the talus accumulations along the hillside, it appears there are thousands of cubic yards of this material that could be easily mined.MetamorphismThe following hypotheses are based on field observations, aided by the use of a 20x hand lens. The laboratory analyses completed for this project were only to determine rock quality, in reference to material specifications. No other petrologic studies were completed.There were three rock types encountered during this exploration program, they were a metasandstone, a dolomitic marble, and a quartz mica schist (discussed below). MetasandstoneThe metasandstone was a whitish-tan to buff colored rock composed of fine grained quartz sand. The unit’s primary bedding planes are preserved and there are slight variations to its strata. There are thin stratum layers where no individual sand grains were visible and appeared to be cemented by the intergrowth of quartz within its void spaces. This was particular notable at one of the test pit locations (Station 1,125 South / 0 West) where the rock had more of a quartzite texture than other metasandstone observed. However, the majority of the strata was cemented by CaCO3 and contained sand grains that were visible with a hand lens. The metasandstone broke into tabular pieces, ranging from a couple of inches to approximately 1 foot thickness, along the bedding plains of this type of stratum. Photographs of the metasandstone are provided in Appendix C.Dolomitic marbleThe dolomitic marble is a blackish grey color. Much of its characteristic features have been altered by the partial recrystallization of its matrix. This rock has small angular breccia clasts that are cemented by calcite and still retains some foliation. There are small vugs that are partially filled with euhedral quartz and calcite crystals. There are also small discontinuous calcite and milky quartz veins. The dolomitic marble has strong manganese oxide staining along its fractures. Photographs of the dolomitic marble are provided in Appendix C.Quartz mica schistThe QMS was a reddish grey color, it’s well foliated and composed primarily of muscovite mica that varies from medium to coarse grained. The silica content of the QMS also varies; some of the QMS was more siliceous than others but most of the QMS examined had at least some small interbedded layers that were siliceous. No garnets or amphiboles were seen in any of the QMS. Photographs of the QMS are provided in Appendix C.The protoliths of the rocks described above are sandstone (sand), dolostone (carbonate muds), and shale (clays and silts), which are indicative of a transgressive/regressive shallow marine depositional environment. These protoliths were then subjected to medium-grade, regional metamorphism during the formation of the Brooks Range (part of the North American Cordillera), making their age of deformation as occurring during the Late Mesozoic to Early Cenozoic eras. The premise that these protoliths have undergone medium-grade metamorphism is supported by the fact that the shale has been metamorphosed into a well foliated schist; as opposed to low-grade metamorphism which would have metamorphosed the shale into a slate or phyllite. Additionally, if the proliths were subjected to high-grade metamorphism then the sandstone would have metamorphosed into a quartzite, the schist would likely have developed some garnets and/or amphiboles, and the dolomitic marble would have been completely recrystallized and non-foliated.Glacier ErraticDuring the excavation of Test Pit 1,125 South / 0 West (66.99810° N, 160.51233° W) a glacial erratic was discovered. It was found buried within the colluvium at an elevation of ≈ 460 feet above mean sea level and ≈ 250 vertical feet above the surface of the proposed gravel quarry site. The erratic was a large oblong shaped boulder that’s been rounded by stream action. The boulder is ≈ 2-feet in diameter along its major axis and 1-feet in diameter at its minor axis. It’s composed entirely of massive quartz (bull quartz) and weighs ≈ 250 pounds. Photographs of this boulder are provided in Appendix C.Other than this sole rounded boulder, there were not any alluvial boulders, gravels, or sand discovered to be deposited along either of the two prospect lines. Additionally, there were not any drainage channels on the eastern hillside that would have had enough stream energy to mechanically round a boulder of that size and composition. Therefore, it’s concluded that this boulder was not deposited near the site through stream transport; instead it was transported there by ice. However, it was not moraine deposition since there was no evidence of glacial till on the hillside. As such, the following hypothesis is provided to explain how this large alluvial boulder could have been deposited at that elevation on the hillside:The Brooks Range experienced extensive alpine glaciation during the Pleistocene Epoch. These glaciers stored enormous volumes of water that was released relatively quickly as the glaciers melted during the Late Pleistocene. In part, some of this melt water created a huge outwash plain throughout much of the lower Squirrel River valley, as well as the upper Kobuk River valley; evident by the unconsolidated silty sand and gravel deposits that can extend several hundred feet in elevation above the valley floor (USGS Bulletin 480, 1910, The Squirrel River Placers, Philip S. Smith, pages 306-319). At the confluence of the Squirrel and Kobuk rivers the outwash plain is restricted in width by the adjacent hills that exist on both sides of their respective valleys. Given the conditions of enormous volumes of water being released quickly and topographic features that restricts the width of the floodplain, it’s conceivable that a large ice jam occurred downstream and close to the confluence of these two rivers sometime during the Late Pleistocene. The ice jam would have temporarily dammed the rivers and caused their water levels to rise. If a piece of ice having the subject boulder incorporated in it was being carried down river during this occurrence it could have floated or have been pushed to the side of this flooded landscape and became lodged against its shore. This piece of ice remained lodged emplace on the hillside after the water levels receded and deposited the boulder when it melted.ACKNOWLEDMENTSI’d like to thank the following Kiana residents for their hospitality and valuable contributions of knowledge and hard work, which helped make this precursory exploration program a successful, in alphabetical order: Bobby AtorukWaylon SchveralfDelores BarrNelson WalkerKevin BlackJohnathan WestlakePaul HenryLarry WestlakeLee’s Sea AirPete Wilson ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download