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HomeMy WebLinkAboutDENSIL THOMPSON Plat# 77-220 S-4344 COMMENTS: ENVIRONMENTAL SANITATION: CASE NU "R S-4344 PETITION FOR ~REZONING 'I~PECI AL EXCEPTION ~CATION R~UBDIVISlON DATE RECEIVED COMMENT TO PLANNIN~ BY March DEPARTMENT OF HEALTH AND ENVIRONMENTAL PROTECTION PLATTING OR PLANNING AND ZONING CASE REVIEW OFJ3ensll-T~ompson-~5~P~oposed Subdivisi on o~o~i-.1~_3 (~' .T. 1BN: RI~_ Sec 8~ ~Alaska, located in t~~, d ~ SW 1/4 of the above described Section an Township, and totalling 2.500 acres (includings Rights of Way to be dedicated to the Public), into 2 Lots. 1977 FOR MEETING OF April 7, 1977 ~ of ..,~7 Cases PUBLIC WATEB NOT AVAILABLE ;EWE R SERVICE PETITION AREA. ENGINEERING: ~-]]) 5-4344 - DENSIL THOMPSON SUBDIVISION, LOTS A & B The ,qun,.,p,.,l~t,~ of -' - AnchoraB¢ has rcceived a petition from Dentil Thom?son to rcsubdi;id¢ approximately 2.5 ~cres from one lot into two lots. The peal[ion are~ is located no,'th of Birchwood Loop.  The plat was approved subject to: ..- 4040 "B" STREET, ANCHORAGE, ALASKA 99503 PHONE: 907-279-2581 January 17, 1977 W.O. #17962 Mr. Densil Thompson 2467 Tulik Drive Anchorage, Alaska 99503 Subject: Subsurface Investigation Lot 137, Sec. 8, T.15N., R.1W., SM. Dear Mr. Thompson: Transmitted herein in accordance with your instructions are the results of the above referenced investigation as performed by us on January 12 and 13, 1977. The scope of this project is investigation for suitability of an on-site sewerage system. Included in this transmittal are: Vicinity Map Test Hole Logs Explanatory Information Figure 1 Table A Sheets 1-3 The exploration was conducted using a Nodwell mounted Mobile Drill Model B-50, drill rig with a continuous flight solid stem auger. The rig is owned and operated by Denali Drilling, Inc. Drilling was supervised and the test holes logged by Mr. Terry Barber, geologist with Alaska Testlab. Test hole #1 was placed approximately 165' north .and 50' east of the SW corner of the above mentioned lot. Test hole #2 was placed approximately 165' north and 85' west of the SE corner. The logs of these test holes are included in Table A of this report. In interpreting the logs, it would be helpful to utilize the explanatory information contained in Sheets t to 3 of this report. When drilling was completed a 3/4" slotted PVC pipe was inserted in each hole to aid in determining the free water level. For the percolation test, the test hole was filled with water and left overnight to saturate. On returning the next day, the hole was refilled with water and the drop in the water level carefully monitored over the next 60 minutes. S 3 4 APR ? Mr. Densil Thomps~n January 17, 1977 Page 2 This procedure is not standardized percolation test, however, we understand that the Anchorage Department of Environmental Quality prefers tests performed in this manner to evaluate a site for a proposed on-site sewerage system. Using the above test, the observed minimum percolation rate was: Test Hole #1 Test Hole #2 14 minutes/inch 20 minutes/inch No water table was observed during drilling, but it should be noted that the free water level normally fluctuates seasonally and with precipitation. We hope this report meets your present needs. If we can be of further service, please feel free to contact us. Very truly yours, ALASKA TESTLAB R. Mark Hansen APPROVED: Melvin R.¥~ichols, P.E. RMH:MRN:gf TNI.~ .VICINITY I:"1 G. I 'I~AF= "TF-.51' HOL,,,~ LOC.A,TI 0 %ate: Log9 By: 1/12/77 Terry Barber Test Hole Table A WO #17962 Depth in Feet From To 0.0 2.0 2.0 5.0 5.0 16.0 Soil Description F-4, brown sandy silt, ML, with roots and organics. F-2, brown very silty gravelly sand, SM; fine and medium, dry, medium density, rounded and subrounded particles to 3/4". F-4, brown gravelly sandy silt, SM, dry, hard, all sand sites, rounded and subrounded particles to 3/4". Bottom of Test Hole: Frost Line: Free Water Level: 16.0' 0.0' - 1.0' None Observed Sample Depth 1 5.' 2 10' 3 16' Blows/6" M% Type of Sample G G G Dry Streng,th Grou~ Unified SM SM SM Remarks: Type of Sample, G=Grab, SP = Standard Penetration, U = Undisturbed. Dry Strength, N=None, L=Low, M=Medium, H=High. Group refers to similar material,' this study only. ate: Logged By: 1/12/77 Terry Barber Test Hole #2 Table A WO #17962 Depth in Feet From To 0.0 1.5 1.5 10.0 10.0 16.0 Soil Description F-4, brown silt, ML, damp to wet, with roots and organics. F-2, brown very silty g.[avelly sand, SM, dry, medium to high density, all sand sizes, cobble at 5'. F-4, brown, gravelly sandy silt, SM, dry, hard, all sand sizes, rounded and subrounded particles to 1/2". ~ Bottom of Test Hole: Frost Line: Free Water Level: 16.0' 0.0' - 1.0' None Observed Sample Depth 1 5' 2 10' 3 16' Blows/6" M% Type of Sample G G G Dry Strength Gr9~ Unified SM SM SM Remarks: Type of Sample, G=Grab, SP = Standard Penetration, U = Undisturbed. Dry Strength, N=None, L=Low, M=Medium, H=High. Group refers to similar material, this study only. Test Hole Lo9 - Description Guide The soil descriptions shown on the logs are the best estimate of the soil's characteristics at the time of field examination and as such do not achieve the precision of a laboratory testing procedure. If the log includes soils samples, those samples receive an independent textural classification in the laboratory to verify the field examination, The logs often include tile following items: Depth Interval - usually shown to 0.1 foot, within that zone no significant change in soil type was observed through drill action, direct observation or sampling. Frost Classification -- NFS, Fl, F2, F3, F4, see "Soil Classification Chart" Texture of Soil An e,~gineering classification of the soils by particle size and proportion, see "Soil Classification Chart", note the proportious are approximate and modifications to the soil group due to stratificatio,, inclusions and changes in properties are included. Moisture Content · this is a qualitative measure: d__uf., no or little apparent surface moisture, damp, moisture forms portion of color, less than plastic limit, wet, no free water, often soft, if cohesive soil, saturated, free water may be squeezed out, if a free draining soil; dilatent at natural moisture content, if a non-plastic silt or fine sand. (The moisture content is further defined by reference to Pl, LW, NP, M%or dilatency.) Density - refers to more-or-less nou-cohesive soils, such as sand gravel mixtures with or without a fine fraction, derived from drilling action and/or sample data; usually described as: very loose, loose, medium dense, very dense. General intent is to portray earthwork characteristics. Stiffness - refers to more-or-less cohesive soils and fine grained silts of ~ clay-silt groups. Derived from drill action and/or sample data. Very soft, soft, stiff, very stiff and hard are commonly used terms. Particle size -- The largest particle recovered by the split spoon is 1-3/8", Shelby tube 3", auger flights (minute-man) 2", Auger flights (B-50 hollow stem) 6"-8". Larger particles are described indirectly by action of tile drilling and are referred to as cobbles, Y' to 8", or boulders 8"+. Therefore when reviewing the gradation sheets, if any, the description on the hole log must be considered for anqndication of larger particles. Unified Soil Classification .- This is a two letter code. See Unified Classification sheet for further definition. In some cases AASHO and/or FAA soil classifications may be shown as well as the unified. Atterberg Limits - useful for fine grained and other plastic soils. PI; natural moisture content believed to be less than plastic limit PI+; natural moisture content believed to be between plastic and liquid limits L._~w+; natural moisture content believed to be greater than liquid limit . NP; non. plastic, useful as a modifying materials. description of some silty Dilatency -- is the ability of water to migrate to the surface of a saturated or nearly saturated soil sample when vibrated or jolted - u~ed as an aid to determine if a fine grained soil is a slightly or non-plastic silt or a volcanic ash. Rock flour -- finely ground soil that is not plastic but otherwise appears ~ clayey silt. Organic Content - usually described as Peat, PT, sometimes iucludes dilcrete particles such as wood, coal, etc. as a modifier to an inorganic soil. Quantity described as; trace, or an estimate of volume, or, in case of all organic, -.- as Peat. This may include tundra, muskeg and bog material. Muck .- a modifier used to describe very soft, semi-organic deposits ~y occuring below a peat deposit. Amorphus pea_~t -- organic particles nearly or fully disintegrated. Fibrous Peat - organic particles more-or4ess intact. Bottom of Testhole - includes last sample interval. Frost Line - seasonal frost depth as described by drilling action and/or samples at the time of drilling. Frozen Ground - other than frost line, described by samples, usually includes description of ice content, often will include modified Unified Classification for frozen soils - this is a special case related to permafrost studies. Free Water Level - The free water level noted during drilling. This is not necessarily the static water table at the time of drilling or at other seasons. Static water table determination in other than very permeable soils requires observation wells or piezometer installations, used only m special cases. Blow/6." -. The number of blows of a 140 weight free falling 30" to advance a 2" split spoon 6"; the number of blows for a 12" advance is, by definition, the standard penetration. ,,4% - natural moisture content of the soil sample, usually not p-~'formed on clean sands or gravels below the water table. Type of Sample ,SP, refers to 2" split spoon driven into the soil by 140 pound weight, a disturbed sample, S, thin wall tube, "Shelby" used to obtain undisturbed samples of fine grained soil, G, "grab" disturbed sample from auger flights or wall of trench, (2, cut sample, undisturbed sample from wall of trench. Dry. Strenl~th - a useful indicator of a soil's clayey fraction, N=None, L=Low, M=Medium, H=High -- The samples are placed into apparently similar groups based or and texture and are arbitrarily assigned a group letter. Further disturbed tests including Atterberg Limits, grain size, moisture-density relationship, etc. may be performed on the group and are assumed to reflect the general distrubed characteristics of the soils assigned to the group. This is an important phase of the soil analysis and is used to standardize the various qualitative determinations and to reduce the number of quantitative tests necessary to describe the soil mass. SOIL CLASSIFICATION CHART 30% GRAVEL o\O CLAY CLAYEY CLAYEY R OR SILTY S l LTY SAND SANDY GRAVEL \ \ GRAVELLY SAND GRAVEL \ ,o 0 10 20 30 40 50 60 70 80 90 100 GRAVEL (+#4 SCREEN) % BY WEIGHT NONFROST SUSCEPTIBLE SOILS ARE INORGANIC SOILS CONTAINING LESS THAN 3% FINER THAN 0.02 mm. GROUPS OF FROST-SUSCEPTIBLE SOILS: F1 GRAVELLY SOILS CONTAINING BETWEEN 3 AND 20% FINER THAN 0.02 mm. F2 SANDY SOILS CONTAINING BETWEEN 3 AND 15% FINER THAN 0.02 mm. F3 a. GRAVELLY SOILS CONTAINING MORE THAN 20% FINER THAN 0.02 mm. AND SANDY SOILS (EXCEPT FINE SILTY, SANDS) CONTAINING MORE THAN 15% FINER THAN 0.02 mm. b. CLAYS WITH PLASTICITY INDEXES OF MORE THAN 12. EXCEPT VARVED CLAYS. F4 a. ALL SILTS INCLUDING SANDY SILTS. b. FINE SILTY SANDS CONTAINING MORE THAN 15% FINER THAN 0.02 mm. c. LEAN CLAYS WITH PLASTICITY INDEXES OF LESS THAN 12. d. VARVED CLAYS.