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HomeMy WebLinkAboutDerrel's #74 Taft Hwy Drainage StudyDrainage Study Derrel's Mini Storage, #74 Taft Hwy Prepared fora Derrel's Mini Storage 3265 W. Ashlon Ave. Fresno, CA 93722 Steven J. Macias PE. No. 83360 Drainage Study for Derrel's Mini Storage, #74 Taft Hwy Table of Contents 1.0 Purpose 2.0 Assumptions 3.0 Summary of Results 4.0 Appendices Soil Map Proposed Basin Volume Analysis Storm Drainage Basin Tributary Areas Channel Inlet Calculation NOAA Point Precipitation Estimates Addendum to Geotechnical Engineering Investigation Slope Stability Evaluation of Retention Basin Proposed Derrel's Mini Storage 5351 Taft Hwy Bakersfield, California 3-4 1.0 Purpose This study will show the findings for the anticipated storm water runoff for the drainage area in reference to the proposed storage basin for Derrel's Mini Storage, #74 Taft Highway. Derrel's Mini Storage #74, located in Bakersfield, CA, is approximately 13.27 acres. 2.0 Assumptions The following was assumed and applied in this study: 1. A Soils Survey Map and tables has been enclosed in this study 2. The runoff coefficient (c) : Commercial = 0.90 Pavement, Drives & Roofs = 0.95 3. Rainfall Intensity Curves shown on D-1 of the City of Bakersfield, Subdivision & Engineering Design Manual. 4. Caltrans Highway Design Manual Chapter 810 —Hydrology 3.0 Summary of Results The analysis of the proposed drainage basin has been carried out to show the available storage for the new construction of Facility #74 .The basin and its areas can be seen in the Storm Drainage Basin Tributary Areas Exhibit enclosed in this study. A high water mark of approximately 20 ft was used in the design of the storm drainage basin. Using this high water mark and all other resulting tributary areas, the required capacity is 1.79 ac -ft. The proposed storm drainage basin has a total available volume of 8.42 ac -ft. In conclusion, the proposed storm drainage basin has an excess storage volume of 6.63 ac -ft. The analysis of flow for each rectangular channel has been carried out to show the available capacity for the channel draining to the sump. Known flow rates (cfs) were used in the calculations and each proposed channel has been designed to exceed the required capacity of flow draining to the sump. Soil Map Proposed Basin Volume Analysis USDA United States Department of Agriculture MRCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Kern County, California, Southwest Part June 20, 2016 for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. u i o v C v o o 00 C6 m O d O y N V NO C j 8 2 m' wv y h y J rnEam0uEq n_+ao va w w w 10m N o. oa o r 3 n 6 v woZEdvN6mRmmmwNO M E Or a m yOmnam`y w mcM L.. co.wJ U ulN J S«Y E Q 3 po am a oa'i O yE LO E UC = j y QdEy anL d 0Z MNv N m2 F mydN 5 a U mE w a v Copyw CO oC, gm: i> o Vm mm m a LL w 0' 0 U o0a2 m ao E o o ETm«` o EcGOWCyNpm9O mw 6n yV noO2aOvCaEwO Ta c 3- a dm d N aooEya EoZO «y v6ci C O q j a Z 0 mn v N v o N o L y N E CEL a Lw w O OIN j6 gym-' m N o OI N Td M0 6 Q L aFJ C y n m T N u m N y j0 yNy pm m O N w U C m r vEo. E m c dZ mmy cmdEEevmvo82.f omi QE n LcO aQm E• d' y y UU y, 3e J m m mvv L 12 W Ul] y dEm 0WEa0 E 5< U) (n N ryuE 2 N6 T o NLL U am o y uvra m ddi K m ZW y Ti F u f0 WJ y a v ea s q; 3 e` o o aJO « N $ O d Y W a O LL O O O C O O WE 0 0 a p L 16! El l/ Q O i Custom Soil Resource Report intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha - Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report Landform position (three-dimensional): Talf Bakersfield Percent of map unit 3 percent Landform: Alluvial fans, flood plains Landform position (three-dimensional): Talf Kimberlina Percent ofmap unit. 3 percent Landform: Alluvial fans, flood plains Landform position (three-dimensional): Talf Milagro, fine sandy loam Percent of map unit: 3 percent Landform: Alluvial fans, fan skirts Landform position (three-dimensional): Talf Wasco Percent of map unit. 2 percent Landform: Alluvial fans, flood plains Landform position (three-dimensional): Talf Unnamed, slough Percent ofmap unit: 1 percent Landform: Sloughs 231—Milagro fine sandy loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: hnbg Elevation: 290 to 480 feet Mean annual precipitation: 5 to 6 inches Mean annual air temperature: 62 to 65 degrees F Frost -free period: 250 to 300 days Farmland classification: Prime farmland if irrigated Map Unit Composition Milagro and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Milagro Setting Landform: Alluvial fans, fan skirts Down-slope shape: Linear Across -slope shape: Linear, convex Parent material: Alluvium derived from granitoid rock Typical profile AP- 0 to 8 inches: fine sandy loam A - 8 to 14 inches: fine sandy loam 11 Custom Soil Resource Report Unnamed, slough Percent of map unit: 1 percent Landform: Sloughs Landform position (three-dimensional): Talf 13 Calculations Completed By: E. Mepa Calculations Checked By Is Macias Date: 8/2/2016 Wastewater Retention Pond Volume Analysis DERREL'S MINI STORAGE, TAFT HIGHWAY Proposed Pond Tributary Area 1 Tributary Area 2 Proposed Pond V,,= D*(1/6)*(Abnm+4A.1d+AhJ D= 20.00 It AhwP 30,119.00 ft' Amid= 17,920.00 ft' Amin= 8,278.00 ft2 UmiaP 366,923.33 ft Ulolal= ac*ft Required Volume Design Storm: 100 year, 24 -Hour Q=.15F(C*A) Subdivision Design Manual 2.8.2.1 Total Area= 554,562 ft, 12.73 ac c= 0.90 Total Area= 23,084 ft2 0.53 ac c= 0.95 Total Area= 577,646 ft2 13.26 ac Q = 0.152(C•A) =F=---3ac-ft Excess Volume: ac -ft DERREL'S MINI STORAGE 74 TAFT HWY STORM DRAINAGE BASIN 12.0' , /— TOP OF POND: 327.50 200.0' HIGH 1NATER-UL 32LL BOTTOM OF POND: 307.50 121.0' 3s N.T.S. 12.0' Fl:7 J1 I•Ie1'A I i '— 324 S. SANTA FE, STE. A P.O. BOX 7593 VISALIA, CA 93292 TEL: 559.802.3052 FAX: 559.802.3215 I'# PROPOSED BASIN TOTAL VOL. REO'D =1.79 ac -ft TOTAL VOL. AVAILABLE; 8.42 ac -ft TOTAL EXCESS VOL. = 6.63 ac -ft SUMP BOTTOM: 307.50 HE RETENTION BASIN SHALL BE MAINTAINED RIVATELY AND THE CITY OF BAKERSFIELD WILL ' OTASSUME RESPONSIBILITY OVER THE TO BE CONSTRUCTED PER COB BARDS D-11, D-12 AND D-13. TRIBUTARYAREA 1 AREA = 12.73 acres C= 0.90 VOL. REO'D =1.72 ac -ft DERREL'S MINI STORAGE 74 TAFT HWY STORM DRAINAGE BASIN TRIBUTARY AREAS CITY OF BAKERSFIELD RETENTION BASIN CAPACITY EQUATION (2.8.2.1) VOL.=0.15xf (CxA) TRIBUTARY AREA 2 AREA = 0.53 acres C= 0.95 VOL. REO'D = 0.076ac-ft IIffilm. 1 PREPARED BY: 324 S. SANTA FE, STE. A P.O. BOX 7593 VISALIA, CA 93292 TEL: 559.802.3052 FAX: 559.802.3215 Channel Report Hydraflow Express Extension for AutodeskOAUtoCADO Civil 3CO by Autodesk, Inc. 74 Taft Hwy - Channel Inlet (North) Rectangular Area (sgft) Bottom Width (ft) 12.00 Total Depth (ft) 1.50 Invert Elev (ft) 327.50 Slope (%) 50.00 N -Value 0.012 Calculations Compute by: Known Q Known Q (cfs) 4.06 Elev (ft) 330.00 329.50 329.00 328.50 328.00 327.50 327.00 2 4 6 Section 8 Reach (ft) Thursday, Nov 3 2016 Highlighted Depth (ft) 0.04 Q (cfs) 4.060 Area (sgft) 0.48 Velocity (ft/s) 8.46 Wetted Perim (ft) 12.08 Crit Depth, Ye (ft) 0.16 Top Width (ft) 12.00 EGL (ft) 1.15 10 12 14 Depth (ft) 2.50 2.00 1.50 1.00 0.50 0.00 0.50 Channel Report Hydraflow Express Extension for AutodeskOAutoCADO Civil 3DO by Autodesk, Inc. 74 Taft Hwy - Channel Inlet (East) Rectangular Area (sqft) Bottom Width (ft) 12.00 Total Depth (ft) 1.50 Invert Elev (ft) 307.50 Slope (%) 50.00 N -Value 0.013 Calculations Compute by: Known Q Known Q (cfs) 28.90 Thursday, Nov 3 2016 Highlighted Depth (ft) 0.13 Q (Cfs) 28.90 Area (sqft) 1.56 Velocity (ft/s) 18.53 Wetted Perim (ft) 12.26 Crit Depth, Yc (ft) 0.57 Top Width (ft) 12.00 EGL (ft) 5.47 Elev (ft) Section Depth (ft) 310.00 2.50 309.50 2.00 309.00 1.50 308.50 1.00 308.00 0.50 307.50 0.00 307.00 -0.50 0 2 4 6 8 10 12 14 16 Reach (ft) NOAA Atlas 14, Volume 6, Version 2 Location name: Bakersfield, California, USA' r`" Latitude: 35.265°, Longitude: -119.062' Elevation: 348.73 ft`* - source: ESRI Maps .0source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Pence, Sarah Dietz, Sarah Heim, Lillian Hiner, Kazungu Maltada, Deborah Martin, Sandra Pavlovic, Ishani Roy, Cad Trypaluk, Dale Unruh, Fenglin Yen, Michael Yekta, Tan Zhao, Geoffrey Bonnin, Daniel Brewer, Li -Chuan Chen, Tye Parzybok, Jahn Yarchoan NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS -based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 0.068 0.086 0.114 0.138 0.176 0.209 0.246 0.288 0.352 0.408 5 -min 0.055-0.085) 0.070-0.108) 0.092-0.143) 0.111-0.175) 0.137-0.229) 0.159-0.277) 0.183-0.333) 0.209-0.400) 0.246-0.508) 0.277-0.608). 0.097 0.124 0.163 0.198 0.253 0.300 0.353 0.413 0.504 0.585 10 -min 0.079-0.122) 0.100-0.155) 0.131-0.204) 0.159-0.251) 0.196-0.329) 0.228-0.397) 0.263-0.478) 0.300-0.574) 0.353-0.728) 0.397-0.871) 0.118 0.150 0.197 0.240 0.306 0.362 0.426 0.499 0.610 0.707 15-mrn 0.095-0.147) 0.121-0.187) 0.159-0.247) 0.192-0.303) 0.237-0.398) 0.276-0.481) 0.318-0.578) 0.363-0.694) 0.427-0.880) 0.480-1.05) 0.163 IF 0.207 IF 0.272 0.332 1 0.422 0.501 0.589 0.690 0.843 0.978 30 -min 0.132-0.204) 0.167-0.259) 0.219-0.342) 0.265-0.419) 0.328-0.550) 0.382-0.664) 0.439-0.799) 0.501-0.959) 0.590-1.22) 0.663-1.4(3) F -0 -.22 -8 -T 0-.2907F-0-3-82 0.465 0.592 0.702 0.826 0.967 1.18 1.37 60 -min 0.185-0.286) 0.234-0.363) 0.308-0.479) D.372-0.587) 0.460-0.771) 0.535-0.932) 0.616-1.12) 0.703-1.34) 0.827-1.71) 0.929-2.04) 0.328 0-4-'O--]F-O.-'2-'7F-0-6'-'-IF-.0.793 0.9277F 1.07 1.24 1.48 1.692 -hr 0.265-0.410) 0.331-0.513) 0.426-0.664) 0.508-0.802) 0.616-1.03) 0.706-1.23) 0.800-1.46) 0.899-1.72) 1.04-2.14) 1 (1.15-2.52) 0.392 0.490 0.630 0.754 0.937 1.09 1.26 1.44 1.71 1.94 3 -hr 1(0.317-0.490)1(0.396-0.613) 0.508-0.791) 0.603-0.952) 0.727-1.22) 0.830-1.45) 0.937-1.70) 1 (1.05-2.00) 1.20-2.47) 1 (1.32-2.89) 0.502 0.633 0.816 0.976 1.21 1.40 1.61 1.83 2.16 2.43F6 --hr 0.406-0.628) 0.511-0.792) 0.658-1.02) 0780-1.23) 0.939-1.57) 1.07-1.86) 1.20-2.18) 1.33-2.55) 1.51-3.12) 1.65-3.62 ) 0.598 0.778 1.03 1.24 5-61F 11.8117F-2-08- 2.38 2.80 3.14 12 -hr 0.483-0.748) 0.628-0.973) 0.829-1.29) 0.995-1.57) 1 (1.21-2.03) 1 (1.38-2.40) 1.55-2.82) 1.73-3.31) 1.96-4.04) 2.13-4.68) 0.728 0.979 1.33 1.63 2.06 2.41 2.79 3.20 3.79 4.2824•hr 0.662-0.816) 0.890-1.10) 1.20-1.50) 1,46-1.85) 1.78-2.43) 2.04-2 92) 2.29-3.47) 2.54-4.11) 2.88-5.10) 3.13-5.96) 0.840 1.14 1.56 1.92 2.44 2.87 3.33 3.84 4.57 5.18 2 -day 0.764-0.942) 1.03-1.28) 1 (1.41-1.76) 1 (1.72-2.18) 1 (2.11-2.88) 2.42-3.47) 2.73-4.14) 3.05-4.92) 3.47-6.14) 3.78-7.23) 0.903 1.22 1.68 2.08 2.65 3.12 3F ----]F 4.18 4.99 5.673 -day 0.821-1.01) 1.11-1.38) 1.52-1.90) 1.86-2.36) 2.29-3.13) 2.63-3.77 2.97-4.50 3.32-5.36) 3.79-6.71) 4.14-7.92) F -0.95 -87F 13-0-T-1.79 F 2.21 F 2.83 F 3.32 F 3.86 F 4.45 F 5.30 F 6.004 -day 0.871-1.07) 1 (1.18-1.46) 1 (1.62-2.02) 1 (1.99-2.52) 1 2.44-3.34) 1 (2.80-4.02) 1 (3.17-4.80) 3.54-5.71) 1 (4.02-7.12) 1 (4.39-8.39) 1.08 F 1.48 2.04 2.53 3.22 3.77 4.36 4.98 5.87 6.59 7 -day 0.984-1.21) 1 (1.34-1.66) 1 (1.85-2.31) 1 (2.27-2.88) 1 2.78-3.80) 1 (3.18-4.56) 1 (3.58.5.42) 3.96-6.39) 1 (4.46-7.90 4.81-9.21) 1'16 1.59 2.20 2.72 3.47 4.06 4.68 5.34 6.27 7.0170 -day 1.05-1.30) 1.44-1.78) 1.99-2.48) 1 (2.44-3.10) 1 3.00-4.10) 3.43-4.92) 1 (3.84-5.83) 1 (4.25-6.86) 1 (4.76-8.43) 1 (5.12-9.79) 1.40 159-57F-2-73- 3.39 4.34 5.70 5.90 6.74 IF 7.89 8.79 20 -day 1.27-1.57) 1 (1.77-2.19) 2.47-3.07) 1 (3.04-3.65) 1 3.75-5.13) 4.30-6.17) 4.84-7.33) 5.36-8.64) 5.99-10.6) 6.42-12.3) F-1.6-57-2-29- 3.21 4.00 5.15 6.07 7.02 8.03 9.41 10.5 30 -day 1.50-1.84) 1 (2.08-2.57) 2.90-3.61) 11 3.59-4.55) 1 4.45-6.08) 1 5.12-7.34) 5.76-8.73) 6.38-10.3) 7.14-12.7) 7.66-14.6) F-15-97-2-7- 57- 3.85 4.80 6-2-O7F 7.34 8.52 9.75 11.5 12.845•day 1,81-Z23) 2.50-3.09) 3.48-4.34) 31 47) 4. -5 5.36-7.33) 6.19-8.86) 6,99-10.6) 7.75-12.5) 8.69-15.4 ) 9.33-17.6 ) 2.-28--T--31-3 4.38 5.47 7.07 8.37 9.73 11.1 13.1 14.660 -da 2.07-256) 2.85-3.52) 397-4.94) 491-623) 6.10-8.35) 708-10.1) 7.99-12.1) 8.86-14.3) 9.94-17.6) 10.7-20.4 ) t Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Too bl SALEM engineerinq group, inc. September 22, 2016 Ms. Karen Kendall Derrel's Mini Storage, Inc. 3265 W. Ashlan Avenue Fresno, CA 93722 4729 W. Jacquelyn Avenue Fresno, California 93722 559)271-9700 Office 559)275-0827 Fax Job No. 2-214-0117 RE: ADDENDUM TO GEOTECHNICAL ENGINEERING INVESTIGATION SLOPE STABILITY EVALUATION OF RETENTION BASIN PROPOSED DERREL'S MINI STORAGE 5351 TAFT HIGHWAY BAKERSFIELD, CALIFORNIA Dear Ms. Kendall: SALEM Engineering Group, Inc. (SALEM) is pleased to present this addendum regarding the slope stability evaluation of the retention basin. It is our understanding that the retention basin will be cut approximately 20 feet deep with a 2:1 slope (horizontal to vertical). The slope stability analysis was performed using Hoek & Bray (1977) Slope Stability Charts. Slopes were analyzed for stability on the basis of a 2:1 (horizontal to vertical) 20 foot high slope which represents the design conditions. Circular Failure Chart No. 3 was used for this evaluation. This chart assumes that the surface water is four times the slope high behind toe of slope. The basis for the values used includes data generated from the subject geotechnical investigation. The model includes one lithologic unit — the unit parameters (field unit weight, saturated unit weight, cohesion, and friction angle) for this unit are required for stability analysis and are presented below: Litholo6c Unit Cohesion Friction Angle Total Unit Weight Native Alluvium 450 psf 280 120 pcf The results of the slope stability analyses are attached and presented as follows. Slope Height (feet) Factor of Safety 20 2.18 Based on our analyses, the FS of the proposed slopes exceeds the minimum requirements of 1.5 for the long-term condition and 1.1 for the temporary short-term condition. Based on our analyses, the proposed cut slope is considered grossly stable but is highly susceptible to erosion due to the lack of cohesion of some soil layers at the site. Therefore, it's recommended the proposed cut slope be constructed and protected as follows: SAN JOSE, CA i STOCKTON, CA I FRESNO, CA i BAKERSFIELD, CA. i RANCHO CUCAMONGA, CA DALLAS, TX i DENVER, CO i CHARLESTON, SC Project No. 2-214-0117 September 22, 2016 Page No. 2 The slope should not be cut steeper than 2:1 (horizontal to vertical). During construction of the retention basin, it is recommended that the upper soil layers with minimal content of low moisture, non -cohesive material [sand, SP], be benched and replaced with soils from overlying or underlying layers that contain a higher finer -grained soil particle content [silty sand, SM], to create a uniform and less -erodible surface. All other geotechnical engineering recommendations in our geotechnical report Job No. 2-214-0117, dated July 23, 2014, remain applicable. It is important to maintain continuity of geotechnical interpretation and confirm soil conditions encountered during construction to confine design parameters. If SALEM is not retained for those services, SALEM cannot assume any responsibility for others' interpretation of our recommendations, and therefore future performance of the work. If you have any questions, or if we may be of further assistance, please do not hesitate to contact our office at (559) 271-9700. Respectfully Submitted, SALEM ENGINEERING GROUP, INC. 5 Waseal K. Nagi, MS, ETT Geotechnical Project Engineer Central / Northern California SZanimySalem, MS, PE, QRpFESS1p Principal Engineer h SpMMY sq F Fy RCE 52762 / RGE 2549 b Na 2512 Ez9. Dec. 51, 2016 61 SALEM engineering group, inc, Slope Stability Factor of Safety using Hoek & Bray (1977) Slope Stability Chart Data Input (blue cells) Cohesion (psf) c Field Density (pcf) y Shear angle (deg) 4) Slope angle (deg) 0 Slope height (ft) h H:V) slope aspect c y At. tan 0 C y•h-F from chart 1 thru 5) tan 0 F from chart 1 thru 5) Set 1 450 120 28 A27 20 2.0 :1 Caldd Factor of Safety 10.08610.1 10 F= 2.18 t Input from chart 0.24 0.15 F= 2.22 Input from chart Analysis with Circular Slope Stability Charts C tan Y•h - F F Input Chart Slope set # # Ht FS FS 1 3 20 2.18 2.22 The circular failure charts from HOEK & BRAY can be used for both typical tasks in stability analysis, for estimation of the FS as well as for iterative back -analysing She friction angle of an existing circular slide. The different charts assume different conditions of groundwater flow. They are vald for a circular failure rupture starting at a tension crack at the top and running through the toe of the slope. Other charts, not presented in this handouts, can be used to find the location of the critical surface and the tension crack. Chan No 7 Fully drained conditions Chart No 2 Surface water 8 x slope height behind toe of slope Surface water 4 x slope Chart No 3 height behind toe of slope Chan No a Surface water 2 x slope height behind toe of elope Chart No 5 Saturated slope subjected to heavy surface recahrge Fig. 6.1_ Definition of the conditions for using the NOEK&BRAY charts slope stability chart input 0 G 02 G 14 Y x , , r .,. . . , 20 2 l IS m t a m a D £ 0.,# 4 # # & .2 w 7 .a .30 » A Failure Cart NO j Friday, September S &3,&,!± m -slope stability chart . wsA7am Mode] -Excel A RV -21 t i 61 4 E i P 4. g y • , m.-- oma.:— I.-.._! ..:... \.:.; R e yyyf M Rid — •. i~i ¢ .a.._.. 4 LEGEND B-1 Soil Boring Location A RV -2 R -Value Location SITF_ PLAN GEOTECHNICAL ENGINEERING INVESTIGATION PROPOSED Derrel's Mini -Storage 5351 Taft Highway Bakersfield, California All Locations Approximate) oaa 8Y I nPvaweoov: GW JM 2-214-0117 i„ SALEMa K.)