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HomeMy WebLinkAboutBARCLAY CITY S-5396 MUNICIPALITY OF ANCHORAGE DEPARTMENT OF HEALTH & ENVIRONMENTAL PROTECTION ENVIRONMENTAL HEALTH CASE REVIEW WORK SHEET PLATTING BOARD E~ PLANNING & ZONING ;ASE NUMBER S-5396 DATE RECEIVED May 28, 1980 COMMEN~ TO' P'LANNI NG BY June 18, 1980 FOR MEETING OF NAME Barclay City; Section 15 W½ a subdivision of T13N R1E sE¼ NW¼ CASE OF PUBLIC WATER NO,_.~T AVAILABLE TO PETITION AREA PUBLIC SEWER NOT AVAILABLE TO PETITION AREA REVIEWER'S COMMENTS: 71-014 (Rev. 2/78) SOIL AND MATERIALS ENGINEERING AND TESTING John M. Lambe, P.E. 2720 E. Lexington Circle Anchorage, Alaska 99502 907-276-4113 May 27, 1980 Fred Walatka and Associates 3107 W. 29th Ave. Anchorage, Alaska 99503 SUBJECT: Soils Investigation: R. i E., S.M., Alaska W. ~, S.W. ¼, N.W. ¼, Sec. 15, T. 13 N., Dear Fred: In response to your request, I have viewed the subject property, logged seven test pits, and performed laboratory analyses on selected samples from the test pits. This report presents the results of these investigations and my conclu- sions and opinions based on these data. The scope of this effort is limited to the preparation of data and opinions to evaluate the subdivision with regard to the development of on-site sewer systems. FIELD INVESTIGATIONS: Having previously discussed this project with the Municipality of Anchorage Department of Health and Environmental Protection (DHEP), Mr. Barclay and I discussed the requirements of the DHEP in regard to soils investigation required for plat approval. Pursuant to this discussion, Mr. Barclay caused seven test pits to be excavated in the locations shown on Plate 1, the Test Pit Location Sketch, attached. The writer was called to observe these pits on May 20, 1980. The logs of the writer's observations are presented on Plates 2 through 5, the Logs of Test Pits. Samples were taken from some of the test pits and sub- jected to mechanical analyses. The results of these analyses are presented on Plates 6 through 10. The soils observed were sufficiently free of silts to slough excessively sub- sequent to excavation of the test pits. Even with the backhoe standing by on-site, the sloughing soils often precluded the writer from entering the test pit to log the strata. However, the writer expects that a free water level should have been observed during excavation if existing in the test sites, and the lack of observed free water even though the soils observed were wet indi- cates to the writer that the subject site should not be influenced by ground water intrusion into absorption trenches. It should be noted that seasonal fluctuation of water table does and can exist. Seasonal fluctuations are most likely to occur in similar terrain when permeable strata overly impermeable strata and surface runoff migrates through the permeable layer perched on the impermeable layer. This phenomena was not observed in May, 1980 on the site. Fred Walatka and Associates Anchorage, Alaska May 27, 1980 Page Two SITE CONDITIONS: The site is located on the east slope of Eagle River Valley. The soils ob- served are presumed to be coarse scree material. The mechanical analyses of the soils indicated primarily a sandy gravel with some silt with cobbles and boulders and very angular stones. The soils were wet but no free water was observed in any of the test pits during or after excavation, except for some minor seepage observed at the top of a silt layer in Test Pit Four. This seep- age is presumed to be perched on the relatively impermeable layer of silt from the migration of surface water through the more permeable overlying soils. The site is moderate to steeply, sloping to the west, and well removed from Eagle River. A drainage from up-slope bisects the site. The drainage was run- ning at the time of observation, but the writer does not know as to whether this drainage is seasonal, intermittent, or perennial. Kenneth Barclay has constructed a home and on-site sewer system on the north- ernmost lot of the proposed subdivision. The system is reported to be opera- ting adequately. The soils data obtained for that installation is in general agreement with the soils observed during these investigations and is on file at the Municipality of Anchorage DHEP. CONCLUSIONS: The soils observed appear sufficiently permeable to support on-site sewer systems. Due to the apparent permeability of the soils, the remote location of the site, and the numerous cobbles and boulders contained within the de- posits, no percolation tests were performed. However, we feel that based on the visual and laboratory analyses of the soils and the reported performance of the existing systems in the area, that similar systems designed on a basis of 150 square feet per bedroom of absorption area are likely to be adequate. Of primary concern will be the location of the lot lines relative to the drainage so that one hundred feet of separation can be obtained between the drainage and any sewer system. This will be required if the drainage is clas- sified as a creek. We trust the foregoing is sufficient to your immediate needs. While intended to be comprehensive within the scope, this report may not be exhaustive of the possibilities. Therefore, if questions arise or if we can be of any further service, please feel free to call. Very t. ruly yours, ~ John M. Lamb~~, P.E. 7 Civil Engineer 4254-E JML: kcs - JOHH . M.:LAM~E P.E. Laboratory Tests 10- Equipment Elevation LOG OF TEST PIT 1 Case 680 BACK HOE EXIST.GRNDDate 5/20/80 DUFF Brown SILTY SANDY GRAVEL, GM moist Brown SANDY GRAVEL, GP-GM TO GP with numerous cobbles and random boulders, moist to wet Brown SILTY SANDY GRAVEL, GM with layers of SANDY GRAVEL, GP TOTAL DEPTH 16' NO FREE WATER OBSERVED LOG OF TEST PIT 2 Equ;pment Case 680 BACK HOE Elevation EXIST.GRND. Date 5/20/80 DUFF Brown SILTY SANDY GRAVEL, GM Brown SANDY GRAVEL, GP with cobbles and random layers of saturated sandy silt, ML, wet Sieve Analysis 15- Brown SANDY GRAVEL, GP with layers of SILTY SANDY GRAVEL, GM, wet, with cobbles TOTAL DEPTH 15~' NO FREE WATER OBSERVED JOHN M LAMBE P.E. LOG OF TEST PITS 1 & 2 w. ½, S.E. ~, N.W. ~, SEC ~5 T. t 3. N., ~.J~. , ~.2~, A[~KA PLATE 2 .JabNo. 80-263.01 A~w.JML Date 5/26/8__~C 10- 15- Sieve Analysis 15- LOG OF TEST PIT 3 Equlpme.t Case 680 BACK HOE Elevation EXIST.GRND.Dote 5/20/80 DUFF Brown SILTY SANDY GRAVEL, GM wet Brown SANDY GRAVEL, GP with many cobbles and boulders wet Brown SILTY SANDY GRAVEL, GM with layers of SANDY GRAVEL GP-GM TOTAL DEPTH 16' NO FREE WATER OBSERVED LOG OF TEST PIT 4 Equipment Case 680 BACK HOE Elevation EXIST. GRND. D~te 5/20/80 DUFF Brown SILTY SANDY GRAVEL, GM wet Brown SANDY GRAVEL, GP-GM with cobbles and boulders,wet Brown SANDY SILT, ML Black ORGANIC MATERIAL Grey SANDY GRAVEL, GP with cobbles Brown SANDY SILT, ML Grey SANDY GRAVEL, GP moist to wet Grey SILTY SANDY GRAVEL, GM TOTAL DEPTH 16' Minor seepage on silt layer @ 5' JOHN M LAMBE P.E. LOG OF TEST PITS 3 & 4 W. ½, S.E. ¼, N.W. ~, SEC 15 T. 13N.~ R. 1E.~ S.M.~ ALASKA PLATE 3 80-263.01 A~r: JML Oate5/26/80 0 LOG OF TEST PIT 5 Equipment Case 680 BACK HOE ElevationEXIST.GRND. Date 5/20./80 Sieve Analysis Grey to Brown SANDY GRAVEL,GP-GM wet to saturated 15 TOTAL DEPTH 16' NO FREE WATER OBSERVED LOG OF TEST PIT 6 Equipment Case 680 BACK HOE Elevation EXIST. GRND. Date 5/20/80 DUFF Brown SILTY SANDY GRAVEL, GM Grey to Brown SANDY GRAVEL, GP with cobbles and boulders and some silt, wet to saturated Sieve Analysis Brown SANDY GRAVEL, GP-GM wet 15- Grey SILTY SANDY GRAVEL, GM saturated TOTAL DEPTH 1 6' NO FREE WATER OBSERVED JOHN M LAMBE P.E. LOG OF TEST PITS 5 & 6 W. ½, S.E. ~, N.W. ~, SEC 15 T. 13N., R. 1E., S.M., ALASKA PLATE 4 ,~bNo. 80-263.01 AOX:JML Date 5/26/8¢ LOG OF TEST PIT 7 Equ;pment Case 680 BACK HOE Elevatlo. EXIST.GRND. D~te 5/20/80 DUFF, PT Brown SILTY SANDY GRAVEL, GM Brown SANDY GRAVEL, GP-GM wet Sieve Analysis Grey SANDY GRAVEL, GP wet 15- 10- 15- Brown SILTY SANDY GRAVEL, GM wet to saturated TOTAL DEPTH 16' NO FREE WATER LEVEL OBSERVED LOG OF Equipment E levatlon Date JOHN M LAMBE P.E. LOG OF TEST PIT 7 W. ½, S.E ~ · ~, N.W. ~, SEC 15 T. 13N., R. 1E., S.M., ALASKA PLATE ,JobNo. 80-263.01 AI:~:d-~L Date 5/26/8£ U. S. Stondard Sieve Opening Size I U.S.Standard Sieve Numbers I Hydrometer ,~o r "''rill ' 'Il'il ''' II1'1' IIII ~ollii ~tillIIIIIIII III! *~ IIIII[11II1.1 !111 ~o!111 ~- IlllIlllIlll IIII ~ ~o1111 \ IIII 111[I!11 = !!1~ %1111 1111IIII IIII ~Oiill I1~ II11 -- ll[I Illl = ~111 IIII lallllIIII IIII ~'°!II, lill ~.!~11IIII Illl ii[I IIII '~l[ll I~11 IIII ,,,, ,,,. ,olll} Illl Illl "~._ IIIIllll ~ ~5I O. 5 GRAIN ~IZE IN MILLIMETERS I ~RAVEL I SAND ] SILT OR CLAY I COBBLES COARSE [ FINE COARSq MEDIUM ~ FINE Symbol Somple Source Clossificotion PARTICLE SIZE ANALYSIS PLATE JOHN U. LAUBE P.E. w. U. S. Standard Sieve Opening Size I U.S.Stondard Sieve Numbers I Hydrometer , fl llr ,, ,rilllr ,,irllll ,, ii11/i II1111 ~°lilll~i IIIill IIIIII IIIIll IIIIII~ ~ I 0.5 0'1 005 001 0005 GR~IN SIZE JH UILLJMETERS ~ GRAVEL I " SANO i SILT OR CLAY COBaLES COARSE I FINE COARS~ MEDIUM I FINE Symbol Somple Source Clossificotion TEST PIT 4 ~ 11' SANDY GRAIL, GP PARTICLE SIZE ANALYSIS PLATE JOHN M. LAMBE P.E. W, +, ~No.80-263'01 A~r:~L Date 5/26/8G T. 13N., R. 1E., S.M., ALASKA U. S. Standard Sieve Open,ng Size J U.S.Standard Sieve Numbers J Hydrometer ,~3-.2ll/,13/4 I/~5/8 4 810 16 2030405060100 ~001~70 ,OOulrlm,..., ' 'rllllr ''lrllll'~ '' Ill'l I. llllll m lllllll \ IIIIII IIIIII IIIIII llllll ~ ~o1111111 XIIIIII IIIIII I!1111 II!111 ~, IIIIIII ililll I Illlll I!1111 IIIIII ~,,ollllll I II"kll I Illlll II1111 IIIIII ~ IIii111 IIINI IIIIll IIIIII IIIIII I[lllll II!111 'x. IIIIII IIIIII IIiill IIIIII1 !11111 ~. IIIIII Iii111 IIIIII ~°111111 111111 '"'.~ll I III111 IIIIII ,o!111111 !11111 ~~.,, I11111 III111 O OI 0 00~ GRAIN SIZE IN MILLIMETERS CoBBLEs COARSE J FINE COARSI~ MEDIUM J FINE Symbol,Sample Source Classification TEST I~TT PARTICLE SIZE ANALYSIS PLATE JONN M. LAMBE P.E. W. ½, :$.~.. ;~, N.w. 5, s~:c ~5 ~.~ Job No. 80- P-63. O 1 Appr: ,.T[~L Date .5/2_6/80 ~'. 13N., R. 1 ~,., ,S. H., A~,_,AS[~A v t~35080 U. $. Stondord Sieve Opening Size I U.S.$tandord Sieve Numbers I Hyd romelet ~ollli '~ Il[IlIlll Illl ,o1111 I Iliil IIII Iiii IIII JillIllll~[ I~11 Illl !111II111~1 IIII JillIIIIIlfl'l"~-IIII IIII ~l illllIlll Illl 0 ~ tO 5 I 0.5 O'l 005 QOI 0005 GRAIN SIZE IN MILLIMETERS I COBBLES I CO~RSE I FINE ~ym~ol 5omple Source Clossificotion PARTICLE SIZE ~NALYSIS PLATE J0HN ~. LA,BE P.E. ~No 80-~.O~ ~pr:~ D~te ~/~/80 ~.1~.~ ~.1~.~ S.~.~ N350~O U.S. Stondard Sieve Opening Size I U.S.Stondord Sieve Numbers I Hydrometer I 0.5 ~ GRAIN SIZE IN MILLIMETERS Q OI 0.005 0 00~ I GRAVEL ] SAND COBBLES COARSE I FINE COARSEJ MEDIUM J FINE SILT OR CLAY J Symbol Sample Source TEST PIT 7 @ 8' JOHN M. LAMBE P.E. Job No. 80-263.01 N35080 Appr: JMLDate5/26/80 Clossificotion SANDY GRAVEL, GP-GM PARTICLE SIZE ANALYSIS w. ½, S.E. ~, N.W. ~, SEC 15 T. 13N.~ R. 1E.~ S.M.~ ALASKA PLATE 10 MAdOR DM~ION$ TYPICAL NAMES WITH LITTLE CXt gRAVELS NO FINIS SANDI ~ FINES , SC~ ~x~s ~ILTS AND CLAY~ UNIFIED ,~OIL CLASSIFICATION SYSTEM Consol m Consolidation LL ~ Liquid Limit (In ~) PL -- Pie.tlc Limit (In %) Os -- Specific Gravity SA ~ Sieve Anolysls · "Undisturbed' Sample [] Sulk Sample *Tx 320 (2600) TxCU 320 (2600) DS 2750 (2000) FVS 470 *ua 2000 L¥S 7O0 Sheer S~renlth, psf Conflnlnll Preslure, psf Unconsolidated Undrained Trloxlol Consolidated Undrained Trloxlel Consolidated Drained Dlrec! Sheer Field Vane Sheer Unconfined Compression Laboratory Van® Sheer Natal: (I) All stronlth tests on 2.1" or 2.4' dlomeler sampler unless otherwise Indicated. {2) ' Indicates 1.4" diameter .ample. KEY TO TEST DATA Job No. JOHN M LAMBE P.E. Appr: Date_ ~OIL CLASSIFICATION CHART AND KEY T¢~ ~'~'".~,T DATA PLATE 11 NOe09~ 20*'W 329.89' 164.94'