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HomeMy WebLinkAbout3.4 604-12-13 Drainage ReportDrainage(ReportC CASCADE CREEK 604-12-13 STORAGE AREA Garfield County, Colorado Prepared for: Oxy USA, Inc. 760 Horizon Drive, Suite 101 Grand Junction, CO 81506 Office Phone: 970-263-3634 Prepared by: D.R. Griffin & Associates, Inc. 1414 Elk Street, Suite 202 Rock Springs, WY 82901 Office Phone: 307-362-5028 December 22, 2014 D.R. Griffin & Associates, Inc. Job #: 11697 TABLE®F(CONTENTSC 1) INTRODUCTION a) Background b) Location c) Property Description d) Previous Investigations 2) DRAINAGE SYSTEM DESCRIPTION a) Basin Descriptions b) Existing Drainage Conditions c) Offsite Drainage d) Proposed Drainage System Description e) Drainage Facility Maintenance 3) DRAINAGE ANALYSIS AND DESIGN CRITERIA a) Regulations b) Development Criteria c) Hydrologic Criteria d) Hydraulic Criteria 4) CONCLUSIONS a) Compliance b) Design Effectiveness c) Areas in Flood Hazard Zone 5) REFERENCES APPENDIX A: MAPS AND EXHIBITS APPENDIX B: HYDROLOGIC CALCULATIONS APPENDIX C: HYDRAULIC CALCULATIONS SIGNATURE BLOCKS ENGINEER'S STATEMENT LARRY G. BODYFELT STATES THAT I AM BY OCCUPATION A PROFESSIONAL ENGINEER (CIVIL) AND LAND SURVEYOR EMPLOYED BY OXY USA INC. TO PREPARE A DRAINAGE REPORT FOR CASCADE CREEK 604-12-13 STORAGE AREA IN ACCORDANCE WITH THE COLORADO OIL AND GAS COMMISSION (COGCC) REGULATIONS, GARFIELD COUNTY REGULATIONS AND THAT THE WORK WAS DONE UNDER MY AUTHORITY AND SUPERVISION COMMENCING OCTOBER 17, 2014. 1 ALSO STATE THAT THE DESIGN IS COMPLIANT WITH THE NORMAL AND CUSTORMARY INDUSTRY STANDARD OF PRACTICE FOR THIS TYPE AND NATURE OF WORK. LARRY G. BODYFELT, WYOMING PROFESSIONAL ENGINEER (CIVIL) AND LAND SURVEYOR NO. 3507 OWNER'S STATEMENT REVIEWED AND APPROVED BY: MICHAEL C. LOCK, COLORADO PROFESSIONAL ENGINEER NO. 37933 OXY USA INC. HAS REVIEWED THE DRAINAGE REPORT FOR CASCADE CREEK 604-12-13 STORAGE AREA AND ACCEPTS THE RESPONSIBILITY FOR IMPLEMENTING AND MAINTAINING REQUIRED DRAINAGE MITIGATION PROCEDURES. AJIBOYE, OXY7A INC. e o2/0./2acs' INTRODUCTION a) Background CASCADE CREEK 604-12-13 STORAGE AREA is a pad that used to store equipment and surplus materials for use in the Cascade Creek field and surrounding areas. The site was previously graded and developed for use as a well pad. Stormwater and drainage features are existing.1 This report analyzes stormwater flows on and around the existing pad area and change in stormwater runoff quantity resulting from the existing location during expected flows for design storm events. b) Project Location The CASCADE CREEK 604-12-13 STORAGE AREA contains 10.66 acres located in LOT 16 (SW% of the NW%) Section 4 and LOT 13 (SE% of the NE%) Section 5, Township 6 South, Range 97 West, 6th Principal Meridian, Garfield County, Colorado. The pad is located mostly on a high point and has very little upslope watershed contribution which is advantageous for controlling stormwater runoff. Driving directions to the CASCADE CREEK 604-12-13 STORAGE AREA are described as follows: Beginning at the town of DeBeque, Colorado; travel northwesterly on County Road 204 for 5.4 miles to an existing access road. Turn right and travel this road for 22.5 miles to an existing access road. Turn right and travel Northwesterly 0.2 miles to an existing access road. Turn left and travel Northwesterly then Southerly 0.1 miles to the CASCADE CREEK 604-12-13 STORAGE AREA. Center of CASCADE CREEK 604-12-13 STORAGE AREA coordinates are approximated in NAD 83 Datum as: Latitude: 39.553516° N Longitude: 108.233159° W C) Property Description The CASCADE CREEK 604-12-13 STORAGE AREA is located on parcels of land owned by OXY USA INC. The CASCADE CREEK 604-12-13 STORAGE AREA is generally bounded on the southeast by the top of an existing 1.5:1 (H:V) fill slope and bounded on the northwest by an existing benched cut slope. The surface of the CASCADE CREEK 604-12-13 STORAGE AREA pad is mostly native soil consisting of bare dirt with broken shale rock intermixed. Side slopes within the Stormwater Analysis Area have been reclaimed and some grasses have been reestablished. The existing CASCADE CREEK 604-12-13 STORAGE AREA is zoned as Resource Lands as indicated by the Garfield County Zone District Map. d) Previous Investigations To our understanding, no previous investigations of the CASCADE CREEK 604-12-13 STORAGE AREA drainage have been conducted or approved regarding this location. 2) DRAINAGE SYSTEM DESCRIPTION a) Basin Descriptions See Sheet 2 of 4 Appendix A for a map of the delineated watersheds. Stockpiled snow will be directed toward BMPs when practical to allow treatment. Plowed snow will likely be placed near the outer boundary of the pad so drainage swales will collect the snow melt and route it to the sediment traps. W1 is the 4.49 acre basin making up the southwestern portion of the CASCADE CREEK 604-12-13 STORAGE AREA. Stormwater accumulating on W1 is directed by sheet flow to swale 51 and collects in a sediment trap at design point 1, before being released by sheet flow or small rills down the slope to the southeast. W2 is the 4.58 acre basin of the CASCADE CREEK 604-12-13 STORAGE AREA. Stormwater accumulating on W2 is directed by sheet flow to swale S2 and collects in a sediment trap at design point 1, before being released by sheet flow or small rills down the slope to the southeast. WH is the historic location of the Stormwater Analysis Area which includes all the previously identified basins and covers 9.07 acres. b) Existing Drainage Conditions The existing conditions of the CASCADE CREEK 604-12-13 STORAGE AREA consist of a relatively level pad area with projecting 2:1 slopes extending from southeast pad edge down to catch with native contours. The slopes have been reclaimed, and some vegetation is beginning to stabilize the slopes. Soil condition on the pad is mainly graded and leveled for use as a travel surface. All basins in the Stormwater Analysis Area have a hydrologic soil group C designation which has "moderately high runoff potential when thoroughly wet" as defined by the Natural Resources Conservation Service (NRCS). See the hydrologic soil group map produced by the NRCS in Appendix B. Our findings show that the existing CASCADE CREEK 604-12-13 STORAGE AREA reduces the peak flow amount across the boundary of the Stormwater Analysis Area as a result of the pad being constructed. Calculations show that the total peak flow across the boundary of the Stormwater Analysis Area during a 100 year, 24 hour storm has been reduced in comparison historical flows 21.84 cfs to 18.20 cfs. As a result, no retention facilities are required. The Stormwater Analysis Area is located so that no water flows onto the location from any direction. Stormwater that falls within the Stormwater Analysis Area is either retained within the low areas, discharged off the Southwest, South, and East edges of the pad by sheet flow, or collected in drainage ditches and released after being routed through a sediment trap. c) Offsite Drainage The location of the CASCADE CREEK 604-12-13 STORAGE AREA pad was chosen very near a high point so that stormwater falling in the area does not flow onto the Stormwater Analysis Area. d) Proposed Drainage System Description See sheet 2 of 4 of Appendix A for the proposed dimensions of each swale. The V shape swales are to be graded as shown. Extra soil due to swale grading shall be smoothed and compacted to shape the ditch swales and blend with native contours. Swales shall not have a minimum slope less than 0.75%. The swale depths meet or exceed the required depths as calculated in Appendix C. Our calculations show that water velocity through each swale will be greater than 5 feet per second with the expected flow rates during a 100 year, 24 hour storm event, and existing slopes. As a result, energy dissipating and erosion controlling measures are required. The existing sediment trap at base of the fill slope will be utilized to control flow and remove excess sediment before water is released to undisturbed ground. The sediment trap should be constructed as directed by the Urban Storm Drainage Criteria Manual available from the Urban Drainage and Flood Control District with appropriate compaction and riprap outlet. While additional erosion mitigation measures are not expected to be needed, measures shall be taken if erosion issues appear. If more than minor rills occur at the bottom of slopes, wattle logs shall be placed at the bottom of steep slopes in problem areas using "J -hook" methods as described in the Urban Storm Drainage Criteria Manual. If excessive erosion occurs on the steep slopes, erosion control blankets shall be installed according to the Urban Storm Drainage Criteria Manual and the area reseeded and mulched as needed until sufficient vegetation is reestablished to prevent erosion. If stormwater flow through the proposed swales cause damage or change to the swale shape, the swale shall be repaired and wattle logs or riprap shall be installed in the swales at regular intervals in check dam fashion along the length of the swale. Installation of riprap or wattle log check dams shall be as directed by the Urban Storm Drainage Criteria Manual. e) Drainage Facility Maintenance Owner will be required to perform inspections of drainage and sediment facilities after all significant storm events and perform regular maintenance of swales, wattle logs, erosion control mats and sediment trap. Swales should be graded or cleaned out every one to three years and as needed after all significant storm events. Wattle logs should be maintained as needed to retain erosion mitigation properties. Erosion control mats should be maintained and the area reseeded and mulched until the slope is sufficiently stabilized by vegetation. The sediment trap should be dredged and re -graded as needed to maintain depth, dimensions and side slopes. It is not anticipated that additional soil will be disturbed for the use of the proposed site. In the event that soil is moved, the excess soil will be spread out to blend with existing contours and slopes will be kept to a minimum to promote vegetative regrowth and limit erosion. 3) DRAINAGE ANALYSIS AND DESIGN CRITERIA a) Regulations Production of this drainage report follows normal and customary engineering practices for this type and nature of work. Regulations from the Garfield County Land Use and Development Code 7-204 were applied as minimum standards. b) Development Criteria No known drainage constraints have been previously placed on the CASCADE CREEK 604-12-13 STORAGE AREA due to drainage studies, floodplain studies or a master drainage plan. Existing and proposed drainage systems were found to decrease flow from the CASCADE CREEK 604-12-13 STORAGE AREA site compared to historical flows and mitigate runoff effects onto downstream lands. c) Hydrologic Criteria Hydrologic calculations performed on the Stormwater Analysis Area were according to normal and customary engineering practices. The rational method was utilized in development of hydrologic design storms and runoff. See Appendix B for all hydrologic calculations. d) Hydraulic Criteria Hydraulic calculations performed during drainage analysis of the CASCADE CREEK 604- 12-13 STORAGE AREA drainage systems were according to normal and customary engineering practices. Hydraulic flow through each swale was estimated using Manning's Equation. See Appendix C for hydraulic calculations. 4) CONCLUSIONS a) Compliance This report has been prepared in accordance with normal and customary engineering practices for this type and nature of work. b) Design Effectiveness With proper application of the proposed drainage mitigation design presented in this report, runoff effects onto areas downstream of the Stormwater Analysis Area will be minimized during design storms. c) Areas in Flood Hazard Zones There are no flood hazard zones designated by FEMA for the Stormwater Analysis Area. The Stormwater Analysis Area is classified as Zone D. 5) REFERENCES 1.) Stormwater Management Manual Grand Junction Municipal Code Title 26, December 4, 2013 2.) Urban Storm Drainage Criteria Manual Volume 3, Stormwater Best management Practices, November 2010 3.) Hydrology National Engineering Handbook Hydrologic Soil Groups United States Department of Agriculture Natural Resources Conservation Service Part 630 Chapter 7, May 2007 4.) Zone District Map, Garfield County, CO, December 16, 2013 5.) FEMA Flood Insurance Rate Map, Garfield County Colorado, Map Number 0802051ND0A, August 2, 2006 APPENDIXA: C/IAPSANDOXHIBITSC 12/23/2014 J:\11000\11697\DRAINAGE REPORT\11697-ENG.dwg A, ifilf til ft; OXY USA INC (1/3) JOJO PROPERTIES (1/3) _ KOEHLER, DONNA J REVISIONS NO. A B DATE 10/29/2014 12/09/2014 DESCRIPTION ISSUED FOR CLIENT REVIEW FILLED IN RESERVE PITSTO PAD GRADE BY TKM TKM CHK LGB LGB APPR 1414 ELK ST., SUITE 202 ROCK SPRINGS, WY82901 (307)362-5028 OXY 146, CASCADE CREEK 604-12-13 ANNEX STORAGE AREA STORMWATER ANALYSIS TOPOGRAPHIC MAP SCALE: 1" =2,000' JOB No.: 11697 11697 -SW -ANALYSIS GARFIELD COUNTY, COLORADO REV A SHEET 1 OF4 APPENDIXW:IIYDROLOGIC(CALCULATIONSC Precipitation Frequency Data Server http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=39.5551&1... NOAA Atlas 14, Volume 8, Version 2 Location name: De Beque, Colorado, US* Latitude: 39.5551°, Longitude: -108.2321° Elevation: 8613 ft* * source: Google Maps POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Deborah Martin, Sandra Pavlovic, Ishani Roy, Mchael St. Laurent, Carl Trypaluk, Dale Unruh, Michael Yekta, Geoffery Bonnin NOM, National Weather Service, Silver Spring, Maryland PF tabular 1 PF graphical 1 Maps & aerials PF tabular PDS -based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Average recurrence interval (years) Duration 1 2 5 10 25 50 100 200 500 1000 5 -min 0.147 0.186 0.256 0.321 0.420 0.504 0.594 0.692 0.833 0.947 (0.117-0.187) (0.148-0.237) (0.203-0.328) (0.253-0.413) (0.323-0.573) (0.375-0.694) (0.426-0.841) (0.474-1.01) (0.546-1.25) (0.600-1.43) 10 -min 0.215 0.272 0.376 0.470 0.615 0.738 0.870 1.01 1.22 1.39 (0.171-0.274) (0.217-0.347) (0.297-0.480) (0.370-0.605) (0.472-0.839) (0.549-1.02) (0.623-1.23) (0.694-1.48) (0.799-1.83) (0.879-2.10) 15 -min 0.263 0.332 0.458 0.574 0.750 0.900 1.06 1.24 1.49 1.69 (0.209-0.335) (0.264-0.424) (0.363-0.586) (0.452-0.738) (0.576-1.02) (0.670-1.24) (0.760-1.50) (0.846-1.80) (0.975-2.23) (1.07-2.56) 30 -min 0.375 0.480 0.663 0.826 1.07 1.26 1.47 1.70 2.01 2.26 (0.298-0.478) (0.382-0.612) (0.525-0.848) (0.650-1.06) (0.814-1.44) (0.938-1.73) (1.05-2.07) (1.16-2.46) (1.31-3.00) (1.43-3.41) 60 -min 0.484 0.612 0.829 1.02 1.29 1.51 1.74 1.99 2.32 2.58 (0.385-0.617) (0.486-0.780) (0.657-1.06) (0.802-1.31) (0.984-1.74) (1.12-2.07) (1.24-2.45) (1.35-2.87) (1.52-3.46) (1.64-3.91) 2 -hr 0.593 0.743 0.995 1.21 1.52 1.76 2.01 2.28 2.63 2.91 (0.477-0.747) (0.596-0.937) (0.796-1.26) (0.962-1.54) (1.17-2.01) (1.32-2.37) (1.45-2.78) (1.57-3.24) (1.74-3.87) (1.87-4.34) 3 -hr 0.668 0.811 1.05 1.26 1.57 1.81 2.06 2.33 2.69 2.97 (0.540-0.835) (0.655-1.02) (0.848-1.32) (1.01-1.60) (1.21-2.06) (1.36-2.42) (1.50-2.83) (1.61-3.29) (1.79-3.92) (1.92-4.40) 6 -hr 0.802 0.942 1.18 1.39 1.68 1.92 2.17 2.43 2.78 3.06 (0.654-0.991) (0.768-1.17) (0.959-1.47) (1.12-1.73) (1.32-2.19) (1.46-2.54) (1.59-2.94) (1.71-3.39) (1.88-4.01) (2.01-4.47) 12 -hr 0.972 1.11 1.34 1.55 1.87 2.12 2.39 2.69 3.09 3.42 (0.801-1.19) (0.912-1.35) (1.10-1.65) (1.27-1.92) (1.48-2.40) (1.64-2.77) (1.78-3.21) (1.91-3.71) (2.12-4.40) (2.27-4.92) 24 -hr 1.17 1.32 1.59 1.83 2.19 2.48 2.80 3.14 3.62 4.00 (0.969-1.41) (1.09-1.59) (1.31-1.92) (1.50-2.23) (1.75-2.78) (1.94-3.20) (2.11-3.71) (2.26-4.28) (2.50-5.08) (2.69-5.68) 2 -day 1.38 1.59 1.94 2.25 2.69 3.04 3.41 3.80 4.33 4.76 (1.16-1.64) (1.33-1.89) (1.62-2.32) (1.87-2.70) (2.17-3.36) (2.39-3.86) (2.59-4.44) (2.77-5.09) (3.04-5.99) (3.24-6.66) 3 -day 1.55 1.78 2.18 2.52 3.02 3.42 3.83 4.26 4.86 5.33 (1.31-1.83) (1.50-2.11) (1.83-2.59) (2.11-3.01) (2.45-3.75) (2.71-4.30) (2.93-4.95) (3.13-5.67) (3.43-6.66) (3.65-7.40) 4 -day 1.69 1.94 2.37 2.74 3.28 3.71 4.15 4.62 5.26 5.76 (1.43-1.99) (1.65-2.29) (2.00-2.80) (2.30-3.26) (2.67-4.04) (2.95-4.64) (3.19-5.33) (3.41-6.11) (3.73-7.16) (3.98-7.96) 7 -day 2.02 2.31 2.81 3.24 3.84 4.33 4.82 5.34 6.05 6.60 (1.73-2.35) (1.98-2.70) (2.40-3.29) (2.74-3.81) (3.16-4.68) (3.47-5.35) (3.74-6.12) (3.98-6.98) (4.33-8.13) (4.60-9.01) 10 -day 2.29 2.62 3.15 3.61 4.25 4.77 5.29 5.83 6.57 7.14 (1.98-2.66) (2.25-3.03) (2.70-3.67) (3.08-4.22) (3.52-5.14) (3.85-5.85) (4.13-6.66) (4.37-7.55) (4.73-8.76) (5.01-9.66) 20 -day 3.10 3.47 4.08 4.59 5.31 5.87 6.45 7.03 7.82 8.43 (2.69-3.54) (3.01-3.97) (3.53-4.68) (3.96-5.30) (4.43-6.32) (4.79-7.10) (5.09-7.99) (5.33-8.96) (5.71-10.3) (6.00-11.2) 30 -day 3.78 4.21 4.93 5.52 6.33 6.96 7.58 8.22 9.05 9.68 (3.31-4.29) (3.69-4.79) (4.29-5.62) (4.78-6.32) (5.31-7.46) (5.71-8.32) (6.02-9.30) (6.27-10.4) (6.66-11.8) (6.95-12.8) 45 -day 4.66 5.22 6.13 6.87 7.86 8.59 9.31 10.0 10.9 11.6 (4.10-5.25) (4.60-5.89) (5.38-6.94) (5.99-7.80) (6.62-9.15) (7.09-10.2) (7.44-11.3) (7.70-12.5) (8.10-14.1) (8.40-15.2) 60 -day 5.42 6.13 7.26 8.15 9.33 10.2 11.0 11.8 12.8 13.5 (4.79-6.08) (5.42-6.88) (6.39-8.16) (7.14-9.21) (7.88-10.8) (8.44-12.0) (8.84-13.3) (9.11-14.6) (9.52-16.3) (9.83-17.6) 1 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 Top PF graphical 1 of 4 10/17/2014 12:01 PM Precipitation Frequency Data Server http://hdsc.nws.noaa.gov/hdsc/pfds/pfds printpage.html?lat=39.5551&1... PDS -based depth -duration -frequency (DDF) curves Latitude: 39.5551 °, Longitude: -108.2321° 14 1 2 5 10 25 50 100 200 NOAA Atlas 14, Volume 8, Version 2 500 1000 Average recurrence interval (years) Created (GMT)- Fri Oct 17 18:01:46 2014 Back to Top Maps & aerials Small scale terrain Average recurrence interval {years) — 1 2 — 5 — 10 — 25 — 50 — 100 — 200 — 500 — 1000 Duration 5tnin O-rnin 15-m In - 30—fmn — 60 -nu, — 2 -hr — 3 -hr — 6 -hr — 12 -hr -- 24 -hr 2 -day 3 -day 4 -day 7 -day 10 -day 20 -day 30 -day 45 -day 60 -day Grand Junction ldl :;rt Col n :indo I • irrarnc I:Nil Den' 1 ilileto-io cent [, 0 • 5n km Map data © Report a map error 2 of 4 10/17/2014 12:01 PM Precipitation Frequency Data Server http://hdsc.nws.noaa.gov/hdsc/pfds/pfds printpage.html?lat=39.5551&1... Large scale map 2k^ Large scale aerial Map Report a map error Back to Top Imagery Report a map error 3 of 4 10/17/2014 12:01 PM 39° 33' 19" N 39° 33 5" N 737390 737460 737530 737600 Custom Soil Resource Report Map—Hydrologic Soil Group 737670 737740 737810 737880 737950 738020 0 w 737390 737460 737530 737600 Map Scale: 1:3,000 if printed on A landscape (11" x 8.5") sheet. 737670 o N 0 40 80 Meters 160 240 0 100 200 400 600 Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UTM Zone 12N WGS84 21 737740 737810 737880 737950 738020 39° 33' 19" N 39° 33 5" N Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons 0 A 0 A/D 0 0 B/D 0 0 C/D 0 D 0 Not rated or not available Soil Rating Lines •s A A/D eke B , -t B/D s,r C eke C/D e ke D ✓ k Not rated or not available Soil Rating Points O A ® ND ■ B ■ B/D D c O C/D ■ D ® Not rated or not available Water Features Streams and Canals Transportation t++ Rails rkre Interstate Highways US Routes Major Roads Local Roads Background III Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Douglas -Plateau Area, Colorado, Parts of Garfield and Mesa Counties Survey Area Data: Version 7, Sep 22, 2014 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 22, 2010—Sep 2, 2010 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background gery displayed on these maps. Asa result, some minor shifting 22 of map unit boundaries may be evident. Custom Soil Resource Report Table—Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit — Douglas -Plateau Area, Colorado, Parts of Garfield and Mesa Counties (C0682) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 52 Northwater-Adel complex, 5 to 50 percent slopes B 1.5 4.7% 55 Parachute-Irigul complex, 5 to 30 percent slopes C 6.5 21.4 20.8% 68.6% 56 Parachute-lrigul-Rhone association, 25 to 50 percent slopes C 63 Silas loam, 1 to 12 percent slopes C 1.8 5.8% 100.0% Totals for Area of Interest 31.1 Rating Options—Hydrologic Soil Group Aggregation Method: Dominant Condition Component Percent Cutoff. None Specified Tie-break Rule: Higher 23 Design Storms 1 HOUR DURATION DESIGN RAINFALL OBTAINED FROM NOAA ATLAS 14, VOLUME 8, VERSION 2 RECURANCE INTERVAL (YEARS) DEPTH (INCHES) 2 YEAR 0.61 5 YEAR 0.83 10 YEAR 1.02 25 YEAR 1.29 50 YEAR 1.51 100 YEAR 1.74 24 HOUR DURATION DESIGN RAINFALL OBTAINED FROM NOAA ATLAS 14, VOLUME 8, VERSION 2 RECURANCE INTERVAL (YEARS) DEPTH (INCHES) 2 YEAR 1.32 5 YEAR 1.59 10 YEAR 1.83 25 YEAR 2.19 50 YEAR 2.48 100 YEAR 2.80 Hydrologic Analysis CASCADE CREEK 604-12-13 STORAGE AREA Oxy USA 1of5 Job # 11697 D.R. Griffin Associates, Inc. Rock Springs, WY 307-362-5028 Composite Runoff Coefficients "C" Basin I.D. Soil Group C&D (%) Undeveloped (%) Gravel Road (%) Impervious (%) Runoff Coefficients Soil Type C&D 5 YR 25 YR 100 YR W1 100.0% - - - 0.35 0.50 0.58 W2 100.0% - - - 0.35 0.50 0.58 W3 100.0% 0.0% 100.0% 40.0% 0.35 0.50 0.58 W4 100.0% 0.0% 100.0% 40.0% 0.35 0.50 0.58 WH 100.0% 100.0% 0.0% 2.0% 0.17 0.39 0.51 Hydrologic Analysis CASCADE CREEK 604-12-13 STORAGE AREA Oxy USA 2 of 5 Job # 11697 D.R. Griffin Assoicates, Inc. Rock Springs, WY 307-362-5028 Time of Concentration Sub -Basin Data Init. Overland Time( Ti) Travel Time (Tt) Total Tc Check (Urbanized Basins) Basin C5 Area (AC) Lo (ft) Slope % Ti (Min.) Land Type Cv Length Slope % Vel. (FPS) Tt (Min) Ti+Tt (Min) Lgth. (Ft) Tc W1 0.35 4.49 300 2 18.56 BARE 10 252 7 2.65 1.59 20.15 552 13.07 W2 0.35 4.58 300 2 18.56 BARE 10 411 18 4.24 1.61 20.17 711 13.95 WH 0.17 9.07 300 33 9.04 PASTURE 7 300 33 4.02 1.24 10.28 600 13.33 Formulas: Notes: Ti=1.8(1.1-Cs)Lo^0.5/(S^1/3) 1.) Cs = 5 year runoff coefficient V=Cv*(S/100)"0.5 2.) Lo= Length of overland flow, 300' maximum. Tc=(L/180)+10 3.) Overland Time and Travel Time Slope % derived from survey data and Lidar data. Hydrologic Analysis CASCADE CREEK 604-12-13 STORAGE AREA Oxy USA Page 3 of 5 Job # 11697 D.R. Griffin Associates, Inc. Rock Springs, WY 307-362-5028 Rational Method Procedure Design Storm: 25 -Year Developed Direct Runoff Design Point Swale(s) Basin Area (AC) Imperv. Coeff. ( C) Tc (Min.) C*A Pi 1 (in/hr.) Q (cfs) 1 51 W1 4.49 0.40 0.50 20.15 2.25 1.29 2.56 5.76 2 S2 W2 4.58 0.40 0.50 20.17 2.29 1.29 2.56 5.87 WH 9.07 0.02 0.39 10.28 3.54 1.29 3.50 12.38 Formulas: 1=28.9* Pi/(10+Tc)^0.786 Q=CIA Hydrologic Analysis CASCADE CREEK 604-12-13 STORAGE AREA Oxy USA Notes: Pi = Point rainfall for one-hour duration. See Design Storms. Page 4 of 5 Job # 11697 D.R. Griffin Associates, Inc. Rock Springs, WY 307-362-5028 Rational Method Procedure Design Storm: 100 -Year Developed Direct Runoff Ditch Travel Time Design Point Basin Area (AC) Imperv. (dec) Coeff. (C) Tc (Min.) C*A Pi I (in/hr.) Q (cfs) Slope % Flow (cfs) Length (Ft) Velocity (fps) Travel Time (Min) 1 W1 4.49 0.40 0.58 20.15 2.60 1.74 3.46 9.01 7.0 9.01 252 4.84 0.87 2 W2 4.58 0.40 0.58 20.17 2.66 1.74 3.46 9.19 18.0 9.19 411 7.15 0.96 WH 9.07 0.02 0.51 10.28 4.63 1.74 4.72 21.84 Formulas: Notes: I=28.9*Pi/(10+Tc)^0.786 Pi = Point rainfall for one-hour duration. See Design Storms. Q=CIA Hydologic Analysis CASCADE CREEK 604-12-13 STORAGE AREA Oxy USA Page 5 of 5 Job # 11697 D.R. Griffin Associates, Inc. Rock Springs, WY 307-362-5028 APPENDIX L: aIYDRAULIC(CALCULATIONSC Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Friday, Dec 5 2014 S1-100YR SECTION A -A Triangular Highlighted Side Slopes (z:1) = 5.00, 5.00 Depth (ft) = 0.61 Total Depth (ft) = 0.75 Q (cfs) = 9.010 Area (sqft) = 1.86 Invert Elev (ft) = 50.00 Velocity (ft/s) = 4.84 Slope (%) = 7.00 Wetted Perim (ft) = 6.22 N -Value = 0.035 Crit Depth, Yc (ft) = 0.73 Top Width (ft) = 6.10 Calculations EGL (ft) = 0.97 Compute by: Known Q Known Q (cfs) = 9.01 Elev (ft) Section Depth (ft) 51.00 50.75 50.50 50.25 50.00 49.75 0 1 2 1.00 0.75 0.50 0,25 0.00 -0.25 3 4 5 6 7 8 9 10 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Friday, Dec 5 2014 S1-100YR SECTION B -B Triangular Highlighted Side Slopes (z:1) = 5.30, 5.70 Depth (ft) = 0.59 Total Depth (ft) = 0.75 Q (cfs) = 9.010 Area (sqft) = 1.91 Invert Elev (ft) = 50.00 Velocity (ft/s) = 4.71 Slope (%) = 7.00 Wetted Perim (ft) = 6.60 N -Value = 0.035 Crit Depth, Yc (ft) = 0.70 Top Width (ft) = 6.49 Calculations EGL (ft) = 0.93 Compute by: Known Q Known Q (cfs) = 9.01 Elev (ft) Section Depth (ft) 51.00 50.75 50.50 50.25 50.00 49.75 0 1 2 3 4 5 6 Reach (ft) 7 8 9 10 1.00 0.75 0.50 025 0.00 -0.25 11 Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Friday, Dec 5 2014 S2-100YR Triangular Highlighted Side Slopes (z:1) = 1.50, 7.00 Depth (ft) = 0.55 Total Depth (ft) = 0.75 Q (cfs) = 9.190 Area (sqft) = 1.29 Invert Elev (ft) = 50.00 Velocity (ft/s) = 7.15 Slope (%) = 18.00 Wetted Perim (ft) = 4.88 N -Value = 0.035 Crit Depth, Yc (ft) = 0.75 Top Width (ft) = 4.67 Calculations EGL (ft) = 1.34 Compute by: Known Q Known Q (cfs) = 9.19 Elev (ft) Section Depth (ft) 51.00 50.75 50.50 50.25 50.00 49.75 0 1 2 3 4 5 Reach (ft) 6 7 8 1.00 0.75 0.50 0.25 0.00 -0.25 9