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Home My WebLink AboutBARCLAY CITY S-7269 MUNICIPALITY OF ANCHORAGE DEPARTMENT OF HEALTH & ENVIRONMENTAL PROTECTION Environmental Health Division CASE REVIEW WORKSHEET CASE NUMBER: DATE RECEIVED: COMMENTS DUE BY: S-7269 ~_~ ~' A~t,,,~t~ September ~, 1983 SUBDIVISION OR PROJECT ~L~ ..... Lots 2, 3, 4, 5, 6,:& 8 Barclay City ( ) PUBLIC WATER AVAILABLE "~- ( )-PUBLI~ SEWER AVAILABLE TY WATER AVAILABLE 71-014 (Rev. 5/83) JML AMBE AND ASSOCIATES SOIL AND MATERIALS ENGINEERING AND T[$TING Jo~n M. Lambe, P.E. 2720 E. Lexington Clrcte Anchorage, Alaska 99582 907.276-_._4.113 Fred Walatka and Associates 3107 W. 29th Ave. Anchorage, Alaska 99503 SUBJECT: Soils Investigation: R. ! E., S.M., Alaska Dear Fred: W. ½, S.W. ~, N.W. ~, Sec. 15, T. 13 N., In response to your request, ! 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 Depar~nent of Health and Environmental Protection (DHEP), Mr. Barclay and Ii 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 pre~ented 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 s~bject site should not be influenced by ground water intrusion into absorption trenches. It should be noted that seasonal ~uctuation of water table does and can exist. Seasonal fluctuations are most likely to occur in similar terrain when permeable strata overly impermeable '--* and surface runoff migrates through the Pe.~meable layer perched on the S~,~.a ' impermeable layer. This phenomena wes not observed in M~y, 1980 on the site S7 2 6 9 OCT 0 5 1983 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 pres~ned 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 n~nerous 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 wilt be required if the drainage is clas- sified as a creek. We trust the foregoing is sufficient to your inlnediate needs. While intended to be comprehensive within the scope, this report may not be exhaustive of the possibilities. Therefore, i~ questions arise or if we can be of any further service, please feel free to call. JJohn M. Lambe'~ P.E. ( jML: kcs~' JOHhJ La!:~oratory Tests 15- Sieve Analysis 15- JOHN M LAMBE P.E. .Jab No. 80-263.01 .ADc~H--M3~ O~te 5/26/8C LOG Of TEST PIT 1 EClulpment Case 680 BACK HOE Elevation EXIST. GRNDOote 5/20/80 DUFF Brown SILTY SANDY G~LCVEL, moist TO - Bro wu SANDY G~L&¥~L, G~- GM · ~th numerous cobbles ~ud random boulders, moist to wet Brown SILTY SANDY GRAVEL, GM J with layers of SANDY GRAVEL,~ GP TOTAL D~TH 16' NO FREE WATER OBS~-~RVED LOG OF TEST PIT 2 Equ;p~n~ Case 680 BACK HOE EleveHon EXIST.GRND. Dote 5/2Q/80 " DUFF Brown SILTY SANDY GRAVEL, GM Brown SANDY GP-~L, GP with cobbles and random layers of saturated sandy silt, MiL, wet Brown SANDY GRAVE~, 'GP ~th layers of SILTY S.~_NDY GRAVEL, GM, wet, ~_th cobbles TOT~iL D~TH ~ 5~ ' ,,A_~R OBSERVED NO . .tREE ~'' ~S: PITS 1 & 2 LOG OF m.-, ~. W. ~, S.E. ~- N.W. ~- SEC 15 w AL~GKA T. 13. N., -R2,~. ,. S.~',~ , 10 15. Sieve Analysis 15- JOHN M LAMBE .P.E. Aco- .J~·- 0.8. LO0 OF' ""'~'~?' ~"rm '~ EXIST. GP3~D.~:t, 5/2Q/50 DUFF Brown SILTY SANDY GRAV~.~, GM we= Bro w~ S~_.NDY GRAV~, GP w~_th many cobbles ~u'd bcuiders ~_~owu SILTY SA~DY GRAV~, GM. with layers of S~_NDY GP~V~ GP- GM TOTAL D.~-PTE 1 6 NO ~ WATER LOG OF TEST PIT 4 Case 680 ~_ACK HOE EXIST. GR_ND. Om~ 5/20/80 DUFF Brown SILTY SANDY GP~V~, GM wet Bro wu SA_N-DY GR_~, GP- GM w-_~*h cobb~, es ~mdbcu!ders wet Bro~ SA.N'D-V-SIL-, ~ ' .Black ORGANIC MATERIAL Grey SA~h~DY GP_~'~, G? ---- ~th cobbles Brcwu SANDY SILT, ML Grey SA~DY GP~.V~, GP moist to wet Grey'SILTY SA4%'DY GP~'CK~-~, GM TCTAL D~TE 16' Y~lncr seepage on silt ~ ayer ~ 5' LOG OF T~ST pr~ . W. a,, S.E. ~, N.~. a., SEC 15 T. 13N., R. 1E., S.M., Lo~o~o~o~ Tes~ LOG, OF '" ',' '~T? Equipment Case 680 BACK HOE ElevationEXIST.GRMD. Dmte 5/20/80 Sieve Analysis 10 Grey to Brown S~DY GP~kV~,GP-GM wet to saturated --- 15. Sieve knalysis 15- JOHN M LAMBE P.E. JcONo. 80-263.01 AOOcJML Cate 5/26/8( TOTAL D~--q~TH 1 6 ' NO FREE WATER OBSERVED LOG OF TEST .~IT 6 Equ;pm~nt Case 680 BACK HCE EleYat;o, EXIST. GRND. 5:re 5/20/80 DUFF Brown SILTY SANDY G~kV~, GM. Grey to Bro'~a S~NDY GRAV~, GP with cobbles and boulders and some silt, wet to saturated Brown SANDY GRAVEL, GP-GM wet Grey SILTY SANDY GRAVEL, GM saturated ~TkL D~---~TH 16' NO FREE WATER OBS~-~RVED LOG OF TEST PITS 5 & W. ½, S.E. ~,. N.W. ~-., SEC 15 T. t3N., R.~E., S.M., PLATE 4 Lat:::,or ctor'y Sieve 5 10' 15 LOG O~ TEST :IT ? Case 680 BA~[ HOE DUFF, PT ~T~V SANDY GRAV~-~, GM Brown ~ Brown S.~DY GRAVEL, GP- GM ~ wet Grey SANDY GRAV="~, GP wet Brown SILTY S_~DY G_~, GM wet to saturated TCTAL D~TL-' 16 ' FR._-- WATER LEVEL OBSERVED LOG O~ EJevat;on ~ 1(3' JOHN LAgSE P.E. m m mm m m IRLAT~ 5 LJ. S. Stonaora Sie~e Open,hq Size I U.S.Stanaord Sieve Numbers J Hydro~te~ j GRAVEL [ SANO ~ SILT OR CLAY .j COBBLES CO~RSE j FiNE CO~RS~ ~EDIU~ ,] KINE ~ymbol S~mgle Source Classification _ TEST PiT 2 ~ 14~', S~DY GP~, GP-GM ~ P~RTICLE SiZE ~N~LYSIS PLATE JOHN M. LAMBE P.E. s.g. c,. N.W. ~,. SEC 15 W. ~No. 00-263.01 .AOOr~L ~m_5/26/80~ T.13N., R. 1E., S.M., A~S~ / 4 ~ ,- ~vEL i ~NO~ S~LT O~ CL~Y T~T PiT k ~ 1~' S~DY G~, GP ~ PARTICLE StZ~ ~N~LYSlS J ~LATE JOHN M. LAMBE P.E. w. ~, s.z. ~, 5'.'~;. e, s~c ~ ~ U S. Stonciard S;eve Ooen,n~; Size J U.S.Sionc~arcI Sieve Numbers J Hydrometer ,, , 0100 ~ ~ 5 I 0.5 Ol 005 OOt 0005 S~mBol 5ompte Source Cias~ificatian ~ PIT 5 ~ 10': S~DY G~VEL, GP-GM P~RTICLE SIZE ANALYSIS PLATE = JOHN M. LAMBE P.E. W, },~s,s, ~No. 8c.-~6~.o~ .~- ~D~te ~/~/8~ ~.~., ~.~., ~.~., .~~ t SA, N~ ] SILT OR CLAY t PARTICLE SIZE ANaLYSiS PLA JOHN ~. LA,BE ~.E. W. ~. 5.E. =, N.W. ~,_ SEC m U.S.S~anc~r~ Sieve O~e~m~ Sizt I U.S.Star,~:rC~ Sieve Numbers I Hy~ro~l~ GR~IN 51ZE IN ~ILLI~ETE~5 COBB~ES co~sE S) mbo( Som~le Source CJassilicot-ion . m~ S~JDY G~.V~, GP-GM _~ST PIT 7 PARTICLE SIZE ANALYSIS PLATE JOHN _UNIFIED SOIL. CLA,,$$1F'ICATION SYSTE:M [] KEY TO TEST JOO NC. JOHN M LAMBE P.E. AoOr: 9aTe SOIL CLASSIFICATION CHAI~ T AND KEY TO TEST DATA PLATE 11