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Home My WebLink AboutRANGERIDER Lots 1 & 2 Plat# 80-050 S-5269BRD. ~4% I I -oso. Bob Gonzales c/o DOWL Engineers 4040 "B" Street Anchorage, Alaska 99503 'October 15, 1979 W.O. #D12147 Grid #2634 Subject: Subsurface Investigation for Suitability of On-Site Waste Water Disposal System, Lots I and 3, Proposed Gonzales Subdivision Dear Mr. Gonzales: We hereby transmit the results of the above referenced investi- gation performed by Alaska Test!ab on October 9 and 10, 1979. We understand that Lot 16, Sec. 21, T. 12N, R. 3W, S.M. is planned to be subdivided into three lots as shown on Figure 1. The scope of this pro3ect is the investigation for suitability of an on- site sewerage system on Lots 1 and 3. ~ Included in this transmittal are: Site Plan Test Hole Logs Explanatory information Figure 1 Tables A-C Sheets 1-3 Soil and groundwater conditions found on the two lots were quite different. Lot ! and part of Lot 2 is situated on a relatively high hill covered with sand. Boring I encountered granular soil to 11 feet overlying sandy silt which extended to 16 feet, the maximum boring depth. The approximate bounds of the high land is shown on Figure 1. Two borings were drilled on Lot 3. Both encountered relatively deep deposits of peat as described in the boring logs. The groundwater level was near the ground surface. Therefore, a percolation test was not performed in either of these locations on Lot 3. This lot is unsuitable for an on-site waste water disposal system. A holding tank would be required to develop ~ lot for residential usage. The exploration was conducted using a continuous flight solid stem auger drill rig owned and operated by Dena!i Drilling, Inc. The drilling was supervised, the-test holes logged and percola- tion test performed by Mr. O. Hatch, Alaska Testlab geologist/ senior field technician. Bob Gonzales -October 15, 1979 ~age Two When drilling was completed a 3/4 inch slotted PVC pipe was inserted into the 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 water level --carefully monitored over the next 60 minutes. This procedure is not a standardized percolation test, however, -we understand the Municipality of Anchorage, Department of Public Health and Environmental Protection, prefers tests performed in this manner to evaluate a site for proposed on-site sewage system. Using the above test, the observed minimum percolation rate on Lot I was 3 minutes per inch. We recommend the system be designed for an absorption area of 100 square feet per bedroom. This recommendation is based on criteria in the "Manual of Septic Tank Practice", U.S. Department of Health, Education and Welfare, Public Health Service. We recommend that the seepage trenches be inspected prior to installing the system as the above recommendations are b~sed on a six inch diameter test hole. The seepage trench will provide a much clearer picture of subsurface conditions than a test hole. If conditions are different than encountered in the test hole, it may be necessary to modify the design. We hope this report meets your present needs. If we can be of further service, please feel free to contact us. Very sincerely, ALASKA TESTLAB ~ames R. Finley, Jr., P.E. Geotechnical Engineer Approved by: Melvin R. Nichols, P.E. Alaska Testlab Manager JRF/ms Attachments 17 16 I 20 I 2~ SITE PLAN ~Test Hole #1 Table A WO #D12147 Date: 10/9/79 Logged by: O. Hatch .Depth in Feet From To 0.0 3.0 3.0 9.0 9.0 11.0 11.0 16.0' Soil Description NFS, brown Sandy fine to coarse Gravel, damp, dense, rounded particles to 3", GP NFS, brown fine to medium Sand with traces silt, damp, dense, SP/SM F-2, brown Silty fine Sand, damp, dense, SM F-4, brown Sandy Silt with'traces gravel, damp, stiff, non-plastic, ML Bottom of Test Hole: Frost Line: Free Water Level: 16.0 Feet None Observed None Observed Percolation Rate = 2.9 minutes/inch, water level in standpipe at start of test = 5.0 feet Sample Depth Number (feet) Unified Classification 1 5 SP/SM 2 10 SM 3 15 ML Remarks: Ail samples obtained from cuttings brought to surface by auger. See sheets 1-3 for explanatory information. Test Hole #2A ~Table B WO #D12147 Date: 10/9/79 Logged by: O. Hatch Depth in Feet From To 0.0 1.0 1.0 8.0 8.0 11.0 11.0 14.0 14.0 16.0 Soil Description NFS, brown fine to coarse Sand, saturated, SP Brown Peat F-4, gray Sandy Silt with traces of gravel, damp, stif~,~-~as-~, ~ NFS/F-2, gray Gravelly fine to coarse Sand with trace silt, saturated, dense, rounded particles to 2", SP/SM F-4, gray Sandy Silt with trace gravel, damp, stiff, plastic, ML Bottom of Test Hole: Frost Line: iFree Water Level: 16.0 Feet None Observed 0.0 Feet Sample Number Depth (feet) Unified Classification I 5 Pt 2 10 ML 3 15 ML Remarks: Ail samples obtained from cuttings brought to surface by auger. See sheets 1-3 for explanatory information. Test Hole #2B Table C .WO #D12147 Date: 10/9/79 .Logged by: O. Hatch Depth in Feet From To ,0.0 3.0 3.0 9.0 · 9.0 10.0 Soil Description NFS, brown Gravelly Sand, (fill), damp to saturated, SP Brown Peat, damp to saturated, soft, Pt NFS, gray Gravelly Sand, saturated, dense, SP Bottom of Test Hole: Frost Line: Free Water Level: 10.0 Feet None Observed 5.0 Feet While Drilling, Seepage at 0.5 Feet .Sample Number Depth Unified (feet) Classification Remarks: Ail samples obtained from cuttings brought to surface by auger. See sheets 1-3 for explanatory information. 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 testxng 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 the 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 engineering classification of the soils by particle size and proportion, see "Soil Classification Chart". note the proportions are approximate and modifications to the soil group due to stratification, inclusions and changes m properties are included. Moisture Content - this is a qualitative measure: d_[~, 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, ifa 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 PI, LW, NP, M%or dilatency.) Density - refers to more-ordess non-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 t e~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 the drilling and are referred to as cobbles, 3" to 8", or boulders 8"+. Therefore when reviewing the gradation sheets, if any, the description on the hole log must be constricted for an mdtcat~on 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. P1; natural moisture content believed to be less than plastic limit PI+; natural moisture content believed to be between plastic and liquid ITmit s L~w+; natural moisture content believed to be greater than liquid limit . NP; non-plastic, useful as a modifying description of some silty materials. Dilatency - is the ability of water to migrate to the st~rface of a saturated or nearly saturated soil sample when vibrated or jolted -- used 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 similar to a clayey silt. Organic Content - usually described as Peat, PT, sometimes includes discrete particles such as wood. coal, etc. as a modifier to an inorganic soil. Quantity described as: trace, or an estimate of volume, or, in ca~e of alt orgamc, - as Peal This may include tundra, muskeg and bog material Muck .- a modifier used to describe very soft, semi-organic deposits usually occuring below a peat deposit. Amor,~)hus ~eat -~ organic particles nearly or fully disintegrated. Fibrous Peat - organic particles more-or-less 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 reiated 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 in special cases. Blow/6" - The number of blows bfa 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. ,el% ~ natural moisture content of the soil sample, usually not ~"~-furmed on clean sands or gravels below the water table. Type of Sample .- SIP, 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. - a useful indicator of a soil's clayey fraction, N~None, edium, '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, moistureatensity relationship, etc. may be performed on the group and a~'e 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 CLAY 30% GRAVEL CLAYEY OR SILTY SAND CLAYEY SILTY SANDY GRAVEL GRAVELLY SAND GRAVEL 0 1 0 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. Z Z E O'MALLEY 17 ! lG U N S U B D V I D E D ROAD 0 DOW E. IIOTH STREET ACCEPTED FEB 4, 1952 So-So ~CORDEi:T- FILFDIO SURVEYOR'S CERTIFICATE 112! TH AVE EST ACCEPTANCE OF DEDICATION ANCHORAGE HEREBY ACCEPTS FOR PUBLIC USES AND FOR PUBLIC PURPOSES THE REAL PROPERTY DEDICATED ON THIS PLAT. INCLUDING BUT NOT LIMITED TO THE EASEMENTS¢ RtGHTS-OF-WAY¢ ALLEYS¢ ROADWAYS¢ · . 'THOROUGHFARES AND PARKS SHOWN HEREO · [}~l~r.j~AT ANCHORAGEI ALASKA~ THIS;IlJ~mDAY OF HL"~T~'~AL CLERK MAY~R OF ANCF~RAGE ~ALE IN FlIT ' CERTIFICATE OF OWNERSHIP AND DEDICATIbN I (WE)HEREBY CERTIFY THAT I(WE)HOLD THE HEREIN SPECIFIED PROPERTY INTEREST IN THE PROPERTY DESCRIBED HEREON, I(WE)HEREBy DEDICATE TO THE MUNICIPALITY OF ANCHORAGE ALL AREAS OEPICTED FOR USE AS PUBLIC UTILITY EASEMENTS¢ STREETS¢ ALLEYS¢ THOROUGHFARES¢ PARKS AND OTHER PUBLIC AREAS SHOWN HEREON, THERE SHALL BE RESERVED ADJACENT TO THE DEDICATED STREETS SHOWN HEREON A SLOPE RESERVA- TION EASEMENT SUFFICIENT TO CONTAIN CUT AND FILL SLOPES OF 1 5 FEET HORIZONTAL FOR EACH ~ FOOT VERTICAL ( 15 TO I ) OF CUT OR FILL FOR THE PURPOSE OF PROVIDING AND MAINTAINING THE LATERAL SUPPORT OF THE CONSTRUCTED STREETS, THERE IS RESERVED TO THE GRANTORS¢ THEIR HEIRS, SUCCESSORS AND ASSIGNS¢ THE RIGHT TO USE SUCH AREAS AT ANY TIME UPON PROVIDING AND MAINTAINING OTHER /LDEGUATE LATERAL SURPORT¢ AS APPROVED ~Y THE HUNICIPALITY, I(WE) HEREBY AGREE TO THIS PLAT AN~ TO ANY RESTRICTION OR COVENANT APPEARING HEREON AN~ ANY SUCH RESTRICTION OR COVENANT SHALL BE BINDING AND ENFORCA~LE AGAINST PRESENT AND SUCCESSIVE OWNERS OF THIS SUBDIVIDED PROPERTY, NOIARY'S ACKNOWLEPGMENT OF~. · i[ tg~ ¢ .; ",' :t~" ':.:~." P~T APPROVAL ~DAY OF ~ PLATTING BOARD ON THE VICINITY MAP j SCAL~ E: I~ "=:620 >- . ~: ABBOTT ROAD KLATT RD ~ ANG IDE SgBDIVISION _~ DICRIM~- ~WhLD-W~CH' LEE DRAWN ~ ZONING R-6J REF 50-74 FILE NO. 105-96 1980-411