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Home My WebLink AboutSubsoil Study for Septic Field Design 02.17.2021tGrtiffirffü*"" ån grüplêyËð ûrnsd Company 502{) Countv lìoad 154 dìlenr¡,oarl Sprìngs, {ltl ¡ì 1 {r01 Phonc: {9?{-}} {}il 5-?98E fax: {910J q45"8454 enrail : kaglelrvood(a;kurnarusa.corn wn,*,. kri lll ailt sa.o$r.r-i Ofhcel-oc¿tions: Derrver(IIQ).Parker,CìolçrarioSpnngs. ltcn{lcllins.{ilenrvoodSpriirgs,RndSunr¡rtil{'oliniy,Coloratle; February 17,2Ð21 Trish Cerise 16724 Highway 82 Carbondale, Colorado 8l 623 trishtæåq!¿gnsilçsul Subject: Project No. 2l -7-138.1 Subsoil Study for S-çl¡tic.Eicld-Dç$gn, Proposed Residcnces. Lots 2 and 3, Cerise Miuor S hway E2. Gartìeld County, Colorado Dear Trish: As requestecl, Kumar & Associates, Inç. perfnrmecl a subsoil stucly tbr septic field design at the subject site. The study was conducted in accordatrce with our agreement tbr geotechnical engineering services to you elated January 18,2021. The data obtained and our recomniendations based or the proposed construction and subsurface conditions encountered are presented in this report. Evaluation of potential geologic hazard irnpacts on the site is beyond the scope of this stu<ly. Proposed Construction: The prclposed septic field wili be located on Lot 2 on the site as shown on Figure 1. The septic field will serve two houses, û11ç ol't Lot? and orle oû Lot 3. Site Conditions: The lo1is relatively fiat with a slight slope down to the south. Vegetation consists of grass and weeds. There was ¿bout 2 to 3 inches of snow on the site at the time of our site visit on January 24,2A21. Subsurface Conditions: The subsurface conditions at the site r.vere evaluated by excavating two exploratory pits (labeled Pit 3 and Pit 4) at the approximate locations shown on Figure 1. The logs of the pits are presented on Figure 2" The subsoils encountered. below about I foot of topsoil, oonsist af 2% ta 6Yz feet of medium stiff, sandy sihy clay overlying relatively dense, slightly silty sandy gravel with cobbles a¡rd srnall boulders down to the excavated depth of 9 to 972 feet. Results of USDA graciation tests performed on disturbed bulk sanpies of the extremely gravelly sand and silty clay loam are presented on Figures 3 and 4. No free water was observed in the pits at thc time of sxcavation and the soils were moist. TVe expect that seasonal groundwater may be higher than that indicated at the time of pit excavatian on January 2û,2A21. In our experience, gloundwater in this area typically peaks during August due to irrigation in the general area. -2- The septic field has varying subsurface conditions and will likely need to be designed for the finer-grained sandy silty clay soils with the USDA gradation shown on Figure 4, Silty Clay Loam. Limitations: This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this arca at this time. We make no warranty either express or irnplied. The conclusions and recomrnendations submitted in this rqlort are based upon the data obtained from the exploratory pits excavated at the locations indicated on Fig¡ure 1, the proposed typ" of construction and our experience in the area. Our findings include interpolation and extrapolation of the subsurface conditions identified at the exploratory pits and variations in the subsurface conditions may not become evident until excavation is performed. If conditions encountered during construction appear different from those described in this report, we should be notified at once so re-evaluation of the recommendations rnay be made. This report has been prepared for the exclusive use by our client for design purposes. We are not responsible for technical interpretations by others of our information" As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation of our recommendations, and to verify that the recommendations have been appropriately interpreted. Significant design changes may require additional analysis or modifications to the recommendations presented herein. We recommend on-site observation of excavations to verifu the subsoil conditions in the septic disposal area by a representative of the geotechnical engineer. If you have any questions or if we may be of fi,xther assistance, please let us know. Respectfully Subrnitted, Kunrar & Associates. Inc. Daniel E. Hardiq P Rev. by: SLP DEH/kac attachments Figure 1 - Location of Exploratory Pits Figure 2 - Logs of Exploratory Pits Figures 3 and 4 - USDA Gradation Test Results Table 1 - Summary of Laboratory Test Results .l t lryþ ç Kumar & Associates, lnc. ',Project No. 21-7-138.1 I]ll-llv3s llvnlxouddvoozI\-'í-- 'lt ,!.,i,ì ,ii. l' /::1,. .,:: .. . :sç lQ?lt lð?,ç .tc|i;r- ,,^;;;;¡:,;ä,;.,,,t ltdI3v rtoo'9t J01osüd'3V rþO0'9z JO1a,.-.:.ir )41'jV +t?ç+/ ù{l'8î,1-L-lZsolBlcossv I JBun)sJd luorvuotdxl l0 N0trv30tt '61¡{ PIT 5 PIT 4 0 0 F.l¡l r¡Jt! I-F(L t!ô 5 I I J I WC=5.9 GRAVEL=75 SAND=23 SILT= 1 CLAY=1 _ WC=29.8 I GRAVEL=0- SAND=12 SILT=55 CLAY=55 5 t-l¡J l¡Jl! I-t-.L l¡Jô 10 10 SEPTIC AREA LEGEND TOPSOIL; SLIGHTLY SANDY CLAY, ROOTS AND ORGANICS, MEDIUM STIFF, MOIST, DARK BROWN. CLAY (CL); SANDY, W|TH SCATTERED ROUNDED COBBLES, MEDTUM STTFF TO ST|FF, MO|ST, BROWN AND DARK BROWN. USDA CLASSIFICATION SILTY CLAY LOAM. GRAVEL (GM); SANDY, SILTY, WITH COBBLES AND SMALL BOULDERS, DENSE, MOIST, GRAY AND BROWN, ROCKS ROUNDED IN SHAPE. USDA CLASSIFICATION EXTREMELY GRAVELLY SAND. i DISTURBED BULK SAMPLE. NOTES 1, THE EXPLORATORY PITS WERE EXCAVATED WITH A BACKHOE ON JANUARY 20, 2021, 2, THE LOCATIONS OF THE EXPLORATORY PITS WERE MEASUREO APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 5. THE ELEVATIONS OF THE EXPLORATORY PITS WERE NOT MEASURED AND THE LOGS OF THE EXPLORATORY PITS ARE PLOTTED TO DEPTH. 4, THE EXPLORATORY PIT LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY PIT LOGS REPRESENT THE APPROXIMATE BOUNDÀRIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE PITS AT THE TIME OF EXCAVATION. PITS WERE BACKFILLED SUBSEQUENT TO SAMPLING. 7, LABORATORY TEST RESULTS: WC = WATER CONTENT GRAVEL = PERCENT RET (%) AINE (ASTM D 22 I 6) S IEVEDONNO.I 0 E E SAND = PERCENT PASSING NO. 10 SltV SILT = PERCENT PASSING NO. 325 SIEV AND RETAINED ON NO. 525 SIEVE TO PARTICLE SIZE .002mm CLAY = PERCENT SMALLER THAN PARTICLE S|ZE .002mm 21-7 -138.1 Kumar & Associates LOGS OF EXPLORATORY PITS Fî9. 2 *9. t;', HYDROMEÏER ANALYSIS SIEVE ANALYSIS 24H8, 7HR 1 MlN, #325 U,S. STANDARD SERIES #140 #60 #35 +la +10ivtN. 601\llN.#4 3/8' 3/4', t t/2' 3 '100 10 90 20 30 70 ô LiJz. FLI É. t--ztJ É. L¡J(L 40 60 z LO U) o_ Fz tl.'lOÉ L¡l(L 50 50 60 40 70 30 BO 20 90 '10 100 .001 .002 .005 ,009 .019 .045 ,106 .025 ,500 1,00 2.00 4.75 DIAMETER OF PARÏCLES IN MILLIMETERS 9,5 19.0 37.5 16.2 152 203 CLAY COEBLES GRAVEL 75 %SAND 23 %SILT 1 %CLAY 1 % USDA SOIL TYPE: Extremely Gravelly Sand FROM: Pit3@4'-5 / I I I I / / / / SMAI I MEDIUM ßreESILT 21-7-138.1 Kumar & Associates USDA GRADATION TEST RTSULTS Fig. 3 HYDROMEÏER ANALYSIS SIEVE ANALYSIS I I / / / / U.S, STANDARD SERIES #140 #80 #35 #tS #10 CLEAR SQUARE OPENINGS 24HR, 7HR 1 illN, #325 015 #4 3', 5"8', B'1m 1C)90 20 BO 30 70 o LlJz F L¡JÉ FzLI ÉLIù 40 60 z U\ V'' o_ FzL!(JÉL! 0_ 50 50 60 40 70 30 BO 20 '10 100 0,001 .002 .00s .009 .019 .045 106 ,025 .500 1.00 2.00 4.75 9.5 19.0 37.5 16.2 1s2 203 DIAMEÏER OF PARTCLES IN MILLIMEÏERS cuY COBBLES GRAVEL O %SAND 12 %SILT 55 %CLAY 33 % USDA SOIL TYPE: Silty Clay Loam FROM: Pit4@3'-4' sflT 21-7-138.1 Kumar & Associates USDA GRADATION TEST RESULTS Fig. 4 I (+rt *iffiifiåinË$n'"'å; **'TABLE 1SUMMARY OF LABORATORY TEST RESULTSect No. 21-7-138.1Silty Clay LoamSOIL TYPEExtremely GravellySand1JJ('/.)CLAYSILT(/"1I55SAND(w232IUSDA SOIL TEXTUREGRAVEL(/"1750SILT&CLAY("/ùSAND("/")GRADATIONGRAVEL(wNATURALDRYDENSITY(pc0NATURALMOISTURECONTENT("/ù3.929.8DEPTH(ft)4-53-4SATIIPLE LOCATIONPITJ4