Sheep_Creek_UT218(1)_Hydraulics_Report.pdf

Sheep Creek Geologic Loop Road Daggett County, UT

UT FLAP 218(1)

Hydraulic Report

Federal Highway Administration Central Federal Lands Highway Division

February 7, 2020

Executive Summary Hydrologic and hydraulic analyses were conducted for the UT FLAP Sheep Creek Geologic Loop (FR 218) project in Dagget County, UT. The existing culverts along the project corridor will be replaced. The hydraulic capacity design frequency was the 25-year flood based on a low standard road classification.

The culvert hydraulic performance was evaluated using HY-8. The recommended replacement culvert types, sizes and inverts are shown in the following table:

Summary of Proposed Culvert Recommendations

Station Proposed Culvert Length (ft) Upstream Invert (ft)

Downstream Invert (ft) Notes

28+97.50 (2) 8'x4' CBC 40 6487.33 6484.02 Headwall upstream and downstream

33+68.91 30" x 19" 48 6473.61 6471.98 End section upstream and downstream

47+01.41 30" x 19" 38 6427.12 6426.06 End section upstream and downstream

52+64.58 24" 46 6417.65 6411.31 End section upstream (culvert extension)

57+62.35 60" x 38" 44 6403.44 6402.27 End section upstream and downstream

57+69.40 24" 50 6404.65 6403.13 End section upstream and downstream

60+09.39 30" x 19" 38 6394.24 6392.66 End section upstream and downstream

67+49.48 30" x 19" 34 6373.51 6373.05 End section upstream and downstream

71+15.18 24" 38 6365.60 6364.66 End section upstream and downstream

85+86.56 (2) 30" x 19" 34 6336.65 6336.31 End section upstream and downstream

93+21.64 30" x 19" 34 6323.20 6321.91 End section upstream and downstream

95+93.12 30" x 19" 52 6316.56 6315.16 End section upstream and downstream

99+02.68 24" 34 6310.23 6308.55 End section upstream and downstream

107+65.56 30" x 19" 30 6299.13 6298.68 End section upstream and downstream

111+74.53 30" x 19" 34 6289.45 6288.91 End section upstream and downstream i UT218(1) Sheep Creek Loop Road - Hydraulic Report

Table of Contents

1 Project Background Information

2 Hydraulic Design Criteria

3 Hydrology

3.1 Hydrologic Setting

3.2 Available Hydrologic Data

3.3 Regression Equation Estimates

3.4 Rainfall-Runoff Estimate for Unnamed Drainage

3.4.1 Precipitation

3.4.2 Basin Parameters

3.5 Recommended Design Discharges

3.6 Minor Basin Hydrology

4 Hydraulic Analysis

4.1 Sheep Creek Backwater

4.2 Existing Culvert Hydraulic Conditions

4.3 Proposed Culvert Hydraulic Conditions

5 Recommendations

6 References ii UT218(1) Sheep Creek Loop Road - Hydraulic Report

Tables Table 1: Hydraulic Design Criteria Table 2: Major Basin Properties Table 3: Available Peak Streamflow Information Table 4: StreamStats Peak Discharge Estimates at Project Location Table 5: NOAA Atlas 14 24-Hour Point Precipitation Table 6: Unnamed Drainage Basin Parameters (NRCS Method) Table 7: HEC-HMS Peak Discharge Estimates at Unnamed Drainage Basin Table 8: Recommended Design Flows for Major Basins Table 9: Minor Basin Rational Method Peak Flow Table 10: Sheep Creek Estimated Water Surface Elevation at Culvert Crossings Table 11: Existing Culvert Characteristics Table 12: 25-Year Existing Culvert Results Table 13: 25-Year Proposed Culvert Results Table 14: Summary of Proposed Culvert Recommendations

Figures

Figure 1: Project location map Figure 2: Sheep Creek Watershed (HUC10: 1404010605) Figure 3: Minor Culvert Basins

Appendices

Appendix A: Hydrologic Analyses Appendix B: Hydraulic Analyses

Page 1 UT218(1) Sheep Creek Loop Road - Hydraulic Report

1 PROJECT BACKGROUND INFORMATION

The project is located in Daggett County along the Sheep Creek Geologic Loop (FR 218), see Figure 1. The existing roadway is one lane in each direction. The existing paved width varies from 16 to 20 feet, with an average of 18 feet. The proposed project will widen the paved width to a consistent 20 feet and add a 1-foot gravel shoulder. The scope of the project includes roadway widening, minor earthwork, grading, paving, and drainage improvements.

Figure 1: Project location map.

2 HYDRAULIC DESIGN CRITERIA

The Federal Lands Highway Project Development and Design Manual (PDDM) (Federal Lands Highway 2012) establishes the hydraulic design criteria. Based on the project scoping report the road has a design speed of 35 mph and a design average daily traffic (ADT) of 350 vehicles, based on these parameters the

Page 2 UT218(1) Sheep Creek Loop Road - Hydraulic Report road is classified as low standard road for hydraulic design purposes. The applicable design criteria are listed in Table 1.

Table 1: Hydraulic Design Criteria

Road Classification: Low-Standard Road Culverts:

Design Frequency Check Frequency Allowable Headwater

25-year flood Overtopping flood

Minimum of:

• Bottom of aggregate base layer

• HW/D ratio of 1.2 for D > 48", 1.5 for D ≤ 48”

• Unacceptable hazard to human life or property

Ditches:

Design

Frequency Stability Depth

10-year flood 10-year Flood • New: WSEL ≤ bottom of aggregate base layer

• Existing: WSEL ≤ shoulder hinge point

Pavement Drainage:

Design

Frequency Spread Depth

10-year flood, 50-year in sumps

Half of one travel lane

• On-grade and Sags: Allowable spread, not to exceed curb height

• Sumps and Parking Areas: 6”

3 HYDROLOGY

3.1 HYDROLOGIC SETTING

The project is located within the Sheep Creek Watershed (HUC10: 1404010605), see Figure 2. Sheep Creek generally flows from west to east and ultimately drains to the Flaming Gorge Reservoir located approximately 4 miles downstream from the project site. Lodgepole Creek is the only named tributary to Sheep Creek located within the project limits. Based on the USGS National Map (U.S. Geological Survey 2018), there are various irrigation ditches and canals within the Sheep Creek watershed including the Sheep Creek Canal and the Lodgepole Canal. The Utah Division of Water Rights website did not specify the permitted discharges for these canals. According to USGS station 09231000 Sheep Creek Upper Canal in operation from 1950 to 1961 average discharge values on the Sheep Creek Canal ranged from 12 to 27 cfs from May to July. These values are not considered significant compared to the major basin hydrology described in the following sections. For the purposes of the project irrigation operations and trans-basin diversions were not accounted for in the hydrologic analyses.

The existing FR 218 alignment is located adjacent to Sheep Creek. There a are two major (greater than 48”) drainage structures within the project corridor. A double corrugated 49”x33” steel pipe-arch that conveys Lodgepole Creek under FR 218 to Sheep Creek, and a single 60” corrugated metal pipe (CMP) that

Page 3 UT218(1) Sheep Creek Loop Road - Hydraulic Report conveys an unnamed intermittent drainage to Sheep Creek. The contributing drainage basins to the two major crossings and Sheep Creek were delineated using available 10-meter digital elevation model (DEM) information obtained from the USGS National Map. The general basin properties are shown in Table 2.

Figure 2: Sheep Creek Watershed (HUC10: 1404010605)

Table 2: Major Basin Properties

Project Station Stream Crossing Description Drainage Area

(mi2) Mean Basin

Elevation (ft)

28+97.50 Lodgepole Creek Existing (2) 49"x33" 26.1 8,270

57+62.35 Unnamed Drainage Existing 60" CMP 0.45 6,950

Offsite Sheep Creek Near Unnamed Drainage outfall 88.2 9,150

Page 4 UT218(1) Sheep Creek Loop Road - Hydraulic Report

3.2 AVAILABLE HYDROLOGIC DATA

There are no USGS streamflow stations within the project limits. There are two inactive stations on Sheep Creek located approximately 8.8 miles upstream, and 1.7 miles downstream of the confluence with Lodgepole Creek, respectively. Table 3 summarizes the available peak streamflow information. Due to the short period of record and lack of active information the streamflow data was not used for the project.

Table 3: Available Peak Streamflow Information

USGS

Station

Location Latitude Longitude Drainage Area Period of Record Years Status

09232000 Sheep

Creek Near Manila

40°53'10" 109°54'10" 42 mi2 1942 - 1961 20 Inactive

09232500 Sheep

Creek at Mouth

40°56'00" 109°39'20" 111 mi2 1946 - 1961 15 Inactive

3.3 REGRESSION EQUATION ESTIMATES

The StreamStats web application (U.S. Geological Survey 2016) was used to estimate peak flows for the two major crossings. Additionally, peak flows for Sheep Creek at the confluence with the Unnamed drainage were estimated to evaluate tailwater conditions for the major crossings. The Utah StreamStats application uses the equations presented in USGS Report 2007-5158 (Kenney, Wilkowske and Wright 2008) which relate peak discharge to drainage area and mean basin elevation in Utah hydrologic region

1. The results for the two major culverts and Sheep Creek are shown in Table 4.

Table 4: StreamStats Peak Discharge Estimates at Project Location

Percent Chance Exceedance (%)

Return Period (year)

Station 28+98 Lodgepole Creek Peak Flow (cfs)

Station 57+58 Unnamed Drainage

Peak Flow (cfs)

Sheep Creek Peak Flow (cfs)

50 2 211 9 642 20 5 356 21 948 10 10 434 31 1,070 4 25 568 48 1,310 2 50 685 65 1,510 1 100 786 80 1,680

The Utah Region 1 peak flow regression equations were developed using the following ranges of the predictor variables:

• Drainage area: 3.62 to 390 square miles

• Mean basin elevation: 6,420 to 10,500 feet.

Since the Unnamed Drainage basin area falls outside the applicable range a rainfall-runoff model was used in order to compare the regression equation results as described in Section 3.4.

Page 5 UT218(1) Sheep Creek Loop Road - Hydraulic Report

3.4 RAINFALL-RUNOFF ESTIMATE FOR UNNAMED DRAINAGE

3.4.1 Precipitation

The point precipitation values for the project were obtained from NOAA Atlas 14 Volume 1 (Bonnin, et al.

2011) using the Precipitation Frequency Data Server (National Oceanic and Atmospheric Administration 2011). The point precipitation values are assumed to represent precipitation over the entire basin. The point precipitation for a duration of 24 hours and various return periods are shown in Table 5.

Table 5: NOAA Atlas 14 24-Hour Point Precipitation

Percent Chance Exceedance (%)

Return Period (year)

Point Precipitation (inches)

50 2 1.21 20 5 1.51 10 10 1.76 4 25 2.11 2 50 2.40 1 100 2.70

Although NOAA Atlas 14 also provides temporal storm distributions for the study area an SCS Type II temporal distribution was selected for the project following guidance from the UDOT Drainage Manual (Utah Department of Transportation 2018).

3.4.2 Basin Parameters

The NRCS curve number (CN) method (Natural Resources Conservation Service 1997) was used to estimate runoff. A composite CN for the basins was estimated using SSURGO soil information (Natural Resources Conservation Service 2015) and the 2011 national land cover dataset (Multi-Resolution Land Characteristics Consortium 2018). Soils within the unnamed drainage basin are classified predominately as hydrologic soil groups (HSG) C and D. Land cover consists primarily of shrub/scrub, and grassland/herbaceous classes. The NRCS lag time equation and unit hydrograph were used to estimate peak flows from the basins. A summary of basin parameters is shown in Table 6.

Table 6: Unnamed Drainage Basin Parameters (NRCS Method)

Basin Drainage Area (mi2)

Composite

CN

Mean Basin Slope

Basin Length (mi)

Lag Time (min)

Unnamed Drainage (Sta 57+62) 0.45 72.8 39.2 1.57 20.4

Page 6 UT218(1) Sheep Creek Loop Road - Hydraulic Report

The hydrologic computations were carried out using HEC-HMS (U.S. Army Corps of Engineers 2017). The results for various return periods are shown in Table 7.

Table 7: HEC-HMS Peak Discharge Estimates at Unnamed Drainage Basin

Percent Chance Exceedance (%)

Return Period (year)

Station 57+58 Unnamed Drainage

Peak Flow (cfs) 50 2 2 20 5 10 10 10 24 4 25 52 2 50 81 1 100 115

3.5 RECOMMENDED DESIGN DISCHARGES

The recommended design flows for the two major crossings are shown in Table 8. The rainfall-runoff model results were selected for the unnamed drainage basin since they were slightly more conservative for the project design frequencies. Additional details of the hydrologic analysis are provided in Appendix A.

Table 8: Recommended Design Flows for Major Basins

Percent Chance Exceedance (%)

Return Period (year)

Station 28+98 Lodgepole Creek Peak Flow (cfs)

Station 57+58 Unnamed Drainage

Peak Flow (cfs)

Sheep Creek Peak Flow (cfs)

50 2 211 2 642 20 5 356 10 948 10 10 434 24 1,070 4 25 568 52 1,310 2 50 685 81 1,510 1 100 786 115 1,680

3.6 MINOR BASIN HYDROLOGY

There are nine minor culvert locations that will be replaced or added within the project limits. The existing culverts are corrugated metal pipes that range in diameter from 15 to 24 inches. The contributing basins to the minor culverts were delineated using the DEM information previously described. Since the resolution of the 10-meter DEM is coarse compared to the size of the minor basins it was assumed that the entire area between culverts was contributing to the next downstream culvert. Figure 3 shows the minor basin delineation.

Page 7 UT218(1) Sheep Creek Loop Road - Hydraulic Report

Figure 3: Minor Culvert Basins

The rational method (Federal Highway Administration 2002) was used to estimate peak flow from the minor basins. A time of concentration estimate using the Kirpich equation resulted in times less than 5 minutes, therefore a minimum time of concentration of 5 minutes was assumed for all basins. Rainfall intensity was obtained from the NOAA Precipitation Frequency Data Server referenced previously. A runoff coefficient (C) of 0.2 was assumed based on undeveloped basins with sandy soils and steep terrain.

Table 9 summarizes the basin parameters and peak flow results for the 25 and 100 year return periods.

Table 9: Minor Basin Rational Method Peak Flow

Station Drainage

Area (acres)

Time of Concentration

(min)

Rational Runoff

Coefficient (C)

25-year Rainfall

Intensity (in/hr)

100-year Rainfall

Intensity (in/hr)

25-year Peak

Flow (cfs)

100-year Peak Flow

(cfs)

33+68.91 3.1 5 0.2 4.16 6.08 2.6 3.8 47+01.41 31.5 5 0.2 4.16 6.08 26.2 38.3 52+64.58 4.0 5 0.2 4.16 6.08 3.3 4.8 60+09.39 6.4 5 0.2 4.16 6.08 5.3 7.7 67+49.48 13.1 5 0.2 4.16 6.08 10.9 16.0 71+15.18 5.6 5 0.2 4.16 6.08 4.7 6.9 85+86.56 26.0 5 0.2 4.16 6.08 21.6 31.6 93+21.64 14.2 5 0.2 4.16 6.08 11.8 17.3 95+93.12 6.2 5 0.2 4.16 6.08 5.1 7.5 99+02.68 3.6 5 0.2 4.16 6.08 3.0 4.3

107+65.56 16.2 5 0.2 4.16 6.08 13.5 19.7

Page 8 UT218(1) Sheep Creek Loop Road - Hydraulic Report

Station Drainage

Area (acres)

Time of Concentration

(min)

Rational Runoff

Coefficient (C)

25-year Rainfall

Intensity (in/hr)

100-year Rainfall

Intensity (in/hr)

25-year Peak

Flow (cfs)

100-year Peak Flow

(cfs)

111+74.53 6.1 5 0.2 4.16 6.08 5.1 7.4

4 HYDRAULIC ANALYSIS

4.1 SHEEP CREEK BACKWATER

The backwater from Sheep Creek was evaluated to determine potential hydraulic impacts on the major crossings. The available site topographic survey for Sheep Creek was limited to two locations due to adverse ice conditions at the time of the data collection. 10-meter digital elevation model (DEM) topographic information was downloaded from the USGS national map (U.S. Geological Survey 2018).The elevations of the overlapping regions of the DEM and the site specific survey were compared. The elevation differences ranged from -45.2 feet to 14.6 feet, and no discernible elevation shift was obtained.

It was determined that the DEM was not suitable to conduct a hydraulic analysis.

Due to the lack of information a single cross section analysis using Manning’s equation was carried out.

The cross section information in the vicinity of the crossings was obtained by vertically shifting the limited survey cross sections for Sheep Creek. The slope of the channel was estimated based on the 10-meter DEM. The vertical cross section shift was computed from the estimated channel slope and distance along the channel from the representative cross section. A roughness value of 0.035 was assumed for the analysis. The channel depth results for the Unnamed Drainage indicated that water would overtop the channel banks during certain design frequencies. As a conservative assumption the representative cross section for the Unnamed Drainage was extended assuming vertical banks above the highest data points due to the lack of better information. This assumption results in a higher water surface elevation compared to allowing water to flow into the floodplain bench. The estimated water surface elevation results are shown in Table 10. Comparing the Sheep Creek results to the downstream invert of the existing culverts it can be concluded that backwater from Sheep Creek will not control the hydraulic performance of the major culvert crossings.

Table 10: Sheep Creek Estimated Water Surface Elevation at Culvert Crossings

Station Location 10-Year (ft)

25-Year (ft)

50-Year (ft)

100-Year (ft)

28+97.50 Lodgepole Creek 6472.8 6473.2 6473.4 6473.7 57+62.35 Unnamed Drainage 6384.0 6384.4 6384.8 6385.1

4.2 EXISTING CULVERT HYDRAULIC CONDITIONS

Page 9 UT218(1) Sheep Creek Loop Road - Hydraulic Report

The hydraulic performance of the existing major culverts was evaluated using HY-8 (Federal Highway Administration 2017). The existing culvert characteristics shown in Table 11 were obtained from the project field survey. The overtopping elevation is assumed to be the minimum elevation that would cause water to flow into the adjacent roadside ditch and overtop the road east of the culvert location. Tailwater was assumed to be normal depth in the downstream channel. The hydraulic analysis did not consider a capacity reduction due to sediment accumulation in the existing barrels, but field inspection photos indicate that sediment accumulation is present.

Table 11: Existing Culvert Characteristics

Station Number of Barrels

Type Size Length (ft)

US Invert (ft)

DS Invert (ft)

Road Overtopping Elevation (ft)

Ditch Overtopping Elevation (ft)

28+98 2 CMP

Arch 49" x 33" 49.8 6486.4 6484.1 6493.5 6490.7(1)

57+62 1 CMP 60" 42.1 6401.5 6399.0 6408.2 6406.5(1)

Notes:

(1) These elevations would cause water to flow into the roadside ditch to the east and overtop the road east of the culvert location.

The 25-year headwater results for the existing culverts are shown in Table 12. The results for the culvert at 28+98 show that the structure is significantly undersized for the 25-year design frequency. The overtopping flow for the crossing is approximately 128 cfs, which is less than the 2-year peak flow estimate. The results show that the crossing at 57+58 is adequately sized/oversized for the 25-year design frequency. The overtopping flow is 116 cfs which corresponds to a 100-year design flow. Although the existing culvert is oversized it has reached the end of its service life and will be replaced.

Table 12: 25-Year Existing Culvert Results

Station Design Flow (cfs)

Headwater Elevation

(ft)

Headwater Depth (ft) HW/D

Ratio

Overtopping Flow (cfs)

Meets Capacity Design Criteria

28+97.50 568 6491.9 5.54 2.0 128 No 57+62.35 52 6404.4 2.92 0.6 116 Yes

The hydraulic performance of the existing minor culverts was not evaluated. The culverts that have reached the end of their service life will be replaced with a minimum 24-inch equivalent culvert sizes. The proposed condition hydraulic results are described in Section 4.3 below. Additional details of the hydraulic analyses are provided in Appendix B.

4.3 PROPOSED CULVERT HYDRAULIC CONDITIONS

The proposed condition hydraulic analysis was conducted using HY-8 using the same hydrology and assumptions as the existing conditions calculations. Due to cover limitations some proposed culvert locations require the use of elliptical pipes to meet cover requirements. When possible the proposed inverts match the inlet and outlet existing ground elevations. The headwater over depth criterion of 1.2

Page 10 UT218(1) Sheep Creek Loop Road - Hydraulic Report is exceeded at the Lodgepole Creek CBC, therefore a variance from this criterion is proposed. Due to the width of the existing channel and vertical profile constraints the proposed CBC size is the maximum span and height that can fit the site conditions without significant modifications. In addition, due to the limited conveyance capacity of the existing channel and the roadway profile descending to the east flows higher than approximate elevation 6491’ will overtop the channel banks and flow to the east along Sheep Creek road, potentially overtopping the road. Increasing the size of the CBC to meet the theoretical HW/D ratio would have limited impact on this condition therefore the proposed design is considered acceptable. The proposed culvert results are shown in Table 13. Additional details of the hydraulic analyses are provided in Appendix B.

Table 13: 25-Year Proposed Culvert Results

Station Proposed Culvert

Design Flow (cfs)

Headwater Elevation

(ft)

Headwater Depth (ft)

HW/D

Ratio

Meets Capacity Design Criteria

28+97.50 (2) 8'x4' CBC 568.0 6492.9 5.6 1.4* HW/D Ratio exceeded 33+68.91 30" x 19" 2.6 6474.2 0.6 0.4 Yes 47+01.41 30" x 19" 26.2 6428.8 1.7 1.1 Yes 52+64.58 24" 3.3 6418.5 0.8 0.4 Yes 57+62.35 60" x 38" 52.0 6405.9 2.4 0.8 Yes 57+69.40 24" 52.0 6405.9 2.4 0.8 Yes 60+09.39 30" x 19" 5.3 6395.2 0.9 0.6 Yes 67+49.48 30" x 19" 10.9 6375.0 1.5 0.9 Yes 71+15.18 24" 4.7 6366.7 1.1 0.6 Yes 85+86.56 (2) 30" x 19" 21.6 6338.1 1.5 0.9 Yes 93+21.64 30" x 19" 11.8 6324.8 1.6 1.0 Yes 95+93.12 30" x 19" 5.1 6317.5 0.9 0.6 Yes 99+02.68 24" 3.0 6311.2 0.9 0.5 Yes

107+65.56 30" x 19" 13.5 6300.9 1.8 1.1 Yes 111+74.53 30" x 19" 5.1 6290.4 0.9 0.6 Yes

Page 11 UT218(1) Sheep Creek Loop Road - Hydraulic Report

5 RECOMMENDATIONS

The proposed culvert recommendations are shown in Table 14. Additional details of the proposed culverts including layout and construction details are shown in the construction plans.

Table 14: Summary of Proposed Culvert Recommendations

Station Proposed Culvert Length (ft) Upstream Invert (ft)

Downstream Invert (ft) Notes

28+97.50 (2) 8'x4' CBC 40 6487.33 6484.02 Headwall upstream and downstream

33+68.91 30" x 19" 48 6473.61 6471.98 End section upstream and downstream

47+01.41 30" x 19" 38 6427.12 6426.06 End section upstream and downstream

52+64.58 24" 46 6417.65 6411.31 End section upstream (culvert extension)

57+62.35 60" x 38" 44 6403.44 6402.27 End section upstream and downstream

57+69.40 24" 50 6404.65 6403.13 End section upstream and downstream

60+09.39 30" x 19" 38 6394.24 6392.66 End section upstream and downstream

67+49.48 30" x 19" 34 6373.51 6373.05 End section upstream and downstream

71+15.18 24" 38 6365.60 6364.66 End section upstream and downstream

85+86.56 (2) 30" x 19" 34 6336.65 6336.31 End section upstream and downstream

93+21.64 30" x 19" 34 6323.20 6321.91 End section upstream and downstream

95+93.12 30" x 19" 52 6316.56 6315.16 End section upstream and downstream

99+02.68 24" 34 6310.23 6308.55 End section upstream and downstream

107+65.56 30" x 19" 30 6299.13 6298.68 End section upstream and downstream

111+74.53 30" x 19" 34 6289.45 6288.91 End section upstream and downstream

Page 12 UT218(1) Sheep Creek Loop Road - Hydraulic Report

6 REFERENCES

Bonnin, Geoffrey M., Deborah Martin, Bingzhang Lin, Tye Parzybok, Michael Yekta, and David Riley. 2011.

"Precipitation-Frequency Atlas of the United States, Semiarid Southwest (Arizona, Southeast California, Nevada, New Mexico, Utah)." NOAA Atlas 14, Volume 1, National Oceanic and Atmospheric Administration , Silver Springs, MD.

Federal Highway Administration. 2017. HY-8 Culvert Analysis Program. Version 7.50.

Federal Highway Administration. 2002. Hydraulic Design Series No. 2, Second Edition, FHWA -NHI-02-001.

Washington, DC: Federal Highway Administration.

Federal Lands Highway. 2012. "Project Development and Design Manual, Chapter 7 Hydrology and Hydraulics." https://flh.fhwa.dot.gov/resources/design/pddm/.

Kenney, Terry A., Chris D. Wilkowske, and Shane J. Wright. 2008. "Methods for Estimating Magnitude and Frequency of Peak Flows for Natural Streams in Utah." Scientific Investigations Report 2007-5158, U.S. Geological Survey. https://pubs.usgs.gov/sir/2007/5158/.

Multi-Resolution Land Characteristics Consortium . 2018. National Land Cover Database 2011 (NLCD 2011). Multi-Resolution Land Characteristics Consortium (MRLC).

https://data.nal.usda.gov/dataset/national-land-cover-database-2011-nlcd-2011.

National Oceanic and Atmospheric Administration. 2011. Precipitation Frequency Data Server (PFDS).

Silver Springs, MD. Accessed April 2019. https://hdsc.nws.noaa.gov/hdsc/pfds/index.html.

Natural Resources Conservation Service. 1997. "National Engineering Handbook, Part 630 Hydrology."

Washington, DC. https://directives.sc.egov.usda.gov/viewerFS.aspx?hid=21422.

Natural Resources Conservation Service. 2015. Soil Survey Geographic (SSURGO) database. Fort Worth, TX. Accessed April 2019. http://websoilsurvey.nrcs.usda.gov.

U.S. Army Corps of Engineers. 2017. HEC-HMS, Hydrologic Engineering Center Hydrologic Modeling System. Version 4.2.1. Davis, CA.

U.S. Geological Survey. 2016. StreamStats Program. http://streamstats.usgs.gov.

U.S. Geological Survey. 2018. The National Map. Accessed March 2019.

https://viewer.nationalmap.gov/advanced-viewer/.

Utah Department of Transportation. 2018. "Drainage Manual of Instruction."

https://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:5107.

UT218(1) Sheep Creek Loop Road - Hydraulic Report

Appendix A – Hydrologic Analyses

Drainage Basin Maps

Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), swisstopo, © OpenStreetMap contributors, and the GIS User Community

´ 0 1 2 3 4 50.5 Miles

Lodgepole Creek

Sheep Creek

Unnamed Drainage

Map Title: Major Drainage Basins Project: UT218(1) Sheep Creek Loop road Date: May 21, 2019 Map by: Luis Calderón

STA 47+01

31.5 ac STA 85+87

26 ac

STA 107+66

16.2 ac

STA 93+22

14.2 ac

STA 67+49

13.1 ac

STA 60+09

6.4 ac

STA 95+93

6.2 ac

STA 111+75

6.1 ac

STA 71+15

5.6 ac

STA 52+65

4 ac

STA 99+03

3.6 ac

STA 33+68

3.1 ac

0 1,000 2,000

Feet´ Map Title: Minor Drainage Basins Project: UT218(1) Sheep Creek Loop Road Date: February 5, 2020 Map by: Luis Calderón

Regression Equations (StreamStats)

3/28/2019 StreamStats https://streamstats.usgs.gov/ss/ 1/4

East Crossing StreamStats Report

Basin Characteristics

Parameter Code Parameter Description Value Unit

APRAVPRE Mean April Precipitation 1.3 inches

AUGAVPRE Mean August Precipitation 1.05 inches

BSLDEM10M Mean basin slope computed from 10 m DEM 41.2 percent

DECAVPRE Mean December Precipitation 0.46 inches

DRNAREA Area that drains to a point on a stream 0.45 square miles

ELEV Mean Basin Elevation 6950 feet

FEBAVPRE Mean February Precipitation 0.52 inches

Region ID: UT Workspace ID: UT20190328203654308000 Clicked Point (Latitude, Longitude): 40.93953, -109.76009 Time: 2019-03-28 14:37:07 -0600 https://streamstats.usgs.gov/ss/ 2/4

Parameter Code Parameter Description Value Unit

FOREST Percentage of area covered by forest 15.1 percent

JANAVPRE Mean January Precipitation 0.52 inches

JULAVPRE Mean July Precipitation 1.09 inches

JUNAVPRE Mean June Precipitation 1.12 inches

LC11DEV Percentage of developed (urban) land from NLCD 2011 classes 21-24

0 percent

LC11IMP Average percentage of impervious area determined from NLCD 2011 impervious dataset

0.0274 percent

LU92HRBN Percent Natural Herbaceous Upland from NLCD1992 3.67 percent

MARAVPRE Mean March Precipitation 1.03 inches

MAYAVPRE Mean May Precipitation 1.73 inches

NOVAVPRE Mean November Precipitation 0.75 inches

OCTAVPRE Mean October Precipitation 1.19 inches

PRECIP Mean Annual Precipitation 12.2 inches

SEPAVPRE Mean September Precipitation 1.11 inches

SLOP30_10M Percent area with slopes greater than 30 percent from 10-meter NED

60.2 percent

Peak-Flow Statistics Parameters [Region 1]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 0.45 square miles 3.62 390

ELEV Mean Basin Elevation 6950 feet 6420 10500

Peak-Flow Statistics Disclaimers [Region 1]

One or more of the parameters is outside the suggested range. Estimates were extrapolated with unknown errors

Peak-Flow Statistics Flow Report [Region 1]

Statistic Value Unit

2 Year Peak Flood 8.73 ft^3/s https://streamstats.usgs.gov/ss/ 3/4

Statistic Value Unit

5 Year Peak Flood 20.8 ft^3/s

10 Year Peak Flood 30.5 ft^3/s

25 Year Peak Flood 47.9 ft^3/s

50 Year Peak Flood 64.8 ft^3/s

100 Year Peak Flood 79.9 ft^3/s

200 Year Peak Flood 105 ft^3/s

500 Year Peak Flood 139 ft^3/s

Peak-Flow Statistics Citations

Kenney, T.A., Wilkowske, C.D., and Wright, S.J.,2007, Methods for Estimating Magnitude and Frequency of Peak Flows for Natural Streams in Utah: U.S. Geological Survey Scientific Investigations Report 2007-5158, 28 p. (http://pubs.usgs.gov/sir/2007/5158/)

Annual Flow Statistics Parameters [Mean Flow SIR08 5230 Region 1]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 0.45 square miles 11.9 278

PRECIP Mean Annual Precipitation 12.2 inches 22 40.9

Annual Flow Statistics Disclaimers [Mean Flow SIR08 5230 Region 1]

One or more of the parameters is outside the suggested range. Estimates were extrapolated with unknown errors

Annual Flow Statistics Flow Report [Mean Flow SIR08 5230 Region 1]

Statistic Value Unit

Mean Annual Flow 0.126 ft^3/s

Annual Flow Statistics Citations

Wilkowske, C.D., Kenney, T.A., and Wright, S.J.,2009, Methods for Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Utah: U.S. Geological Survey Scientific Investigations Report 2008-5230, 62 p. (http://pubs.usgs.gov/sir/2008/5230/) http://pubs.usgs.gov/sir/2007/5158/ http://pubs.usgs.gov/sir/2008/5230/ https://streamstats.usgs.gov/ss/ 4/4

USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

USGS Software Disclaimer: This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.

USGS Product Names Disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Application Version: 4.3.0 https://streamstats.usgs.gov/ss/ 1/4

West Crossing StreamStats Report

Code Parameter Description Value Unit

APRAVPRE Mean April Precipitation 1.91 inches

AUGAVPRE Mean August Precipitation 1.44 inches

BSLDEM10M Mean basin slope computed from 10 m DEM 28.8 percent

DECAVPRE Mean December Precipitation 0.96 inches

DRNAREA Area that drains to a point on a stream 26.1 square miles

ELEV Mean Basin Elevation 8270 feet

FEBAVPRE Mean February Precipitation 1.07 inches

Region ID: UT Workspace ID: UT20190328204408874000 Clicked Point (Latitude, Longitude): 40.93754, -109.76994 Time: 2019-03-28 14:44:23 -0600 https://streamstats.usgs.gov/ss/ 2/4

Parameter Code Parameter Description Value Unit

FOREST Percentage of area covered by forest 46.2 percent

JANAVPRE Mean January Precipitation 1 inches

JULAVPRE Mean July Precipitation 1.38 inches

JUNAVPRE Mean June Precipitation 1.26 inches

LC11DEV Percentage of developed (urban) land from NLCD 2011 classes 21-24

0.11 percent

LC11IMP Average percentage of impervious area determined from NLCD 2011 impervious dataset

0.0724 percent

LU92HRBN Percent Natural Herbaceous Upland from NLCD1992 13.8 percent

MARAVPRE Mean March Precipitation 1.94 inches

MAYAVPRE Mean May Precipitation 2.23 inches

NOVAVPRE Mean November Precipitation 1.43 inches

OCTAVPRE Mean October Precipitation 1.75 inches

PRECIP Mean Annual Precipitation 16.9 inches

SEPAVPRE Mean September Precipitation 1.43 inches

SLOP30_10M Percent area with slopes greater than 30 percent from 10-meter NED

42.3 percent

Annual Flow Statistics Parameters [Mean Flow SIR08 5230 Region 1]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 26.1 square miles 11.9 278

PRECIP Mean Annual Precipitation 16.9 inches 22 40.9

Annual Flow Statistics Disclaimers [Mean Flow SIR08 5230 Region 1]

One or more of the parameters is outside the suggested range. Estimates were extrapolated with unknown errors

Annual Flow Statistics Flow Report [Mean Flow SIR08 5230 Region 1]

Statistic Value Unit

Mean Annual Flow 4.94 ft^3/s https://streamstats.usgs.gov/ss/ 3/4

Annual Flow Statistics Citations

Wilkowske, C.D., Kenney, T.A., and Wright, S.J.,2009, Methods for Estimating Monthly and Annual Streamflow Statistics at Ungaged Sites in Utah: U.S. Geological Survey Scientific Investigations Report 2008-5230, 62 p. (http://pubs.usgs.gov/sir/2008/5230/)

Peak-Flow Statistics Parameters [Region 1]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 26.1 square miles 3.62 390

ELEV Mean Basin Elevation 8270 feet 6420 10500

Peak-Flow Statistics Flow Report [Region 1]

PIl: Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE:

Standard Error (other -- see report)

Statistic Value Unit SE SEp Equiv. Yrs.

2 Year Peak Flood 211 ft^3/s 62 62 1

5 Year Peak Flood 356 ft^3/s 54 54 1.5

10 Year Peak Flood 434 ft^3/s 53 53 2

25 Year Peak Flood 568 ft^3/s 55 55 2.6

50 Year Peak Flood 685 ft^3/s 57 57 2.9

100 Year Peak Flood 786 ft^3/s 58 58 3.3

200 Year Peak Flood 895 ft^3/s 63 63 3.3

500 Year Peak Flood 1040 ft^3/s 68 68 3.5

Peak-Flow Statistics Citations

Kenney, T.A., Wilkowske, C.D., and Wright, S.J.,2007, Methods for Estimating Magnitude and Frequency of Peak Flows for Natural Streams in Utah: U.S. Geological Survey Scientific Investigations Report 2007-5158, 28 p. (http://pubs.usgs.gov/sir/2007/5158/)

USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

http://pubs.usgs.gov/sir/2008/5230/ https://streamstats.usgs.gov/ss/ 4/4

USGS Software Disclaimer: This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.

USGS Product Names Disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

4/1/2019 StreamStats https://streamstats.usgs.gov/ss/ 1/3

Sheep Creek Upstream of East Crossing

Code Parameter Description Value Unit

APRAVPRE Mean April Precipitation 2.43 inches

AUGAVPRE Mean August Precipitation 1.82 inches

BSLDEM10M Mean basin slope computed from 10 m DEM 22.1 percent

DECAVPRE Mean December Precipitation 1.31 inches

DRNAREA Area that drains to a point on a stream 88.2 square miles

ELEV Mean Basin Elevation 9150 feet

FEBAVPRE Mean February Precipitation 1.53 inches

Region ID: UT Workspace ID: UT20190401144657446000 Clicked Point (Latitude, Longitude): 40.93889, -109.75988 Time: 2019-04-01 08:47:05 -0600 https://streamstats.usgs.gov/ss/ 2/3

Parameter Code Parameter Description Value Unit

FOREST Percentage of area covered by forest 65 percent

JANAVPRE Mean January Precipitation 1.35 inches

JULAVPRE Mean July Precipitation 1.68 inches

JUNAVPRE Mean June Precipitation 1.44 inches

LC11DEV Percentage of developed (urban) land from NLCD 2011 classes 21-24

1.01 percent

LC11IMP Average percentage of impervious area determined from NLCD 2011 impervious dataset

0.0968 percent

LU92HRBN Percent Natural Herbaceous Upland from NLCD1992 6.13 percent

MARAVPRE Mean March Precipitation 2.54 inches

MAYAVPRE Mean May Precipitation 2.68 inches

NOVAVPRE Mean November Precipitation 1.88 inches

OCTAVPRE Mean October Precipitation 2.15 inches

PRECIP Mean Annual Precipitation 21.7 inches

SEPAVPRE Mean September Precipitation 1.81 inches

SLOP30_10M Percent area with slopes greater than 30 percent from 10-meter NED

24.8 percent

Peak-Flow Statistics Parameters [100 Percent (88.2 square miles) Region 1]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 88.2 square miles 3.62 390

ELEV Mean Basin Elevation 9150 feet 6420 10500

Peak-Flow Statistics Flow Report [100 Percent (88.2 square miles) Region 1]

PIl: Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE:

Standard Error (other -- see report)

Statistic Value Unit SE SEp Equiv. Yrs.

2 Year Peak Flood 642 ft^3/s 62 62 1

5 Year Peak Flood 948 ft^3/s 54 54 1.5

10 Year Peak Flood 1070 ft^3/s 53 53 2 https://streamstats.usgs.gov/ss/ 3/3

Statistic Value Unit SE SEp Equiv. Yrs.

25 Year Peak Flood 1310 ft^3/s 55 55 2.6

50 Year Peak Flood 1510 ft^3/s 57 57 2.9

100 Year Peak Flood 1680 ft^3/s 58 58 3.3

200 Year Peak Flood 1820 ft^3/s 63 63 3.3

500 Year Peak Flood 2020 ft^3/s 68 68 3.5

Peak-Flow Statistics Citations

Kenney, T.A., Wilkowske, C.D., and Wright, S.J.,2007, Methods for Estimating Magnitude and Frequency of Peak Flows for Natural Streams in Utah: U.S. Geological Survey Scientific Investigations Report 2007-5158, 28 p. (http://pubs.usgs.gov/sir/2007/5158/)

USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

USGS Software Disclaimer: This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.

USGS Product Names Disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Precipitation Data

4/8/2019 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.9366&lon=-109.7718&data=depth&units=english&series=pds 1/4

NOAA Atlas 14, Volume 1, Version 5 Location name: Manila, Utah, USA*

Latitude: 40.9366°, Longitude: -109.7718° Elevation: 6564.42 ft**

* source: ESRI Maps ** source: USGS

POINT PRECIPITATION FREQUENCY ESTIMATES

Sanja Perica, Sarah Dietz, Sarah Heim, Lillian Hiner, Kazungu Maitaria, Deborah Martin, Sandra Pavlovic, Ishani Roy, Carl Trypaluk, Dale Unruh, Fenglin Yan, Michael Yekta, Tan Zhao, Geoffrey

Bonnin, Daniel Brewer, Li-Chuan Chen, Tye Parzybok, John Yarchoan

NOAA, National Weather Service, Silver Spring, Maryland

PF_tabular | PF_graphical | 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

5-min 0.119 (0.104‑0.141)

0.154 (0.133‑0.183)

0.212 (0.181‑0.251)

0.264 (0.224‑0.312)

0.347 (0.287‑0.412)

0.421 (0.341‑0.503)

0.508 (0.399‑0.614)

0.609 (0.462‑0.748)

0.770 (0.555‑0.967)

0.917 (0.634‑1.18)

10-min 0.181 (0.157‑0.214)

0.235 (0.202‑0.278)

0.323 (0.276‑0.382)

0.402 (0.341‑0.475)

0.528 (0.437‑0.626)

0.641 (0.519‑0.766)

0.773 (0.608‑0.934)

0.927 (0.704‑1.14)

1.17 (0.845‑1.47)

1.40 (0.965‑1.79)

15-min 0.225 (0.195‑0.266)

0.291 (0.250‑0.345)

0.400 (0.342‑0.474)

0.498 (0.423‑0.589)

0.655 (0.542‑0.777)

0.795 (0.643‑0.950)

0.959 (0.753‑1.16)

1.15 (0.872‑1.41)

1.45 (1.05‑1.83)

1.73 (1.20‑2.22)

30-min 0.303 (0.262‑0.358)

0.391 (0.337‑0.464)

0.539 (0.461‑0.638)

0.671 (0.569‑0.793)

0.882 (0.729‑1.05)

1.07 (0.866‑1.28)

1.29 (1.01‑1.56)

1.55 (1.18‑1.90)

1.96 (1.41‑2.46)

2.33 (1.61‑2.99)

60-min 0.375 (0.325‑0.443)

0.484 (0.417‑0.575)

0.666 (0.571‑0.789)

0.831 (0.704‑0.981)

1.09 (0.903‑1.29)

1.33 (1.07‑1.58)

1.60 (1.26‑1.93)

1.92 (1.45‑2.35)

2.42 (1.75‑3.04)

2.88 (2.00‑3.70)

2-hr 0.470 (0.412‑0.544)

0.593 (0.518‑0.687)

0.793 (0.689‑0.917)

0.972 (0.836‑1.13)

1.26 (1.06‑1.47)

1.53 (1.25‑1.79)

1.85 (1.47‑2.18)

2.22 (1.71‑2.67)

2.82 (2.06‑3.48)

3.37 (2.36‑4.24)

3-hr 0.533 (0.471‑0.614)

0.673 (0.593‑0.771)

0.878 (0.770‑1.01)

1.07 (0.925‑1.22)

1.36 (1.16‑1.57)

1.61 (1.34‑1.87)

1.92 (1.56‑2.26)

2.28 (1.79‑2.72)

2.87 (2.17‑3.51)

3.42 (2.48‑4.27)

6-hr 0.679 (0.604‑0.770)

0.850 (0.756‑0.969)

1.08 (0.953‑1.23)

1.28 (1.12‑1.45)

1.57 (1.36‑1.79)

1.81 (1.54‑2.07)

2.08 (1.74‑2.40)

2.42 (1.98‑2.83)

2.99 (2.37‑3.56)

3.50 (2.70‑4.32)

12-hr 0.822 (0.742‑0.921)

1.02 (0.921‑1.15)

1.28 (1.14‑1.43)

1.50 (1.33‑1.68)

1.82 (1.60‑2.05)

2.09 (1.80‑2.37)

2.38 (2.01‑2.73)

2.69 (2.23‑3.12)

3.25 (2.61‑3.86)

3.75 (2.93‑4.55)

24-hr 0.974 (0.882‑1.08)

1.21 (1.10‑1.34)

1.51 (1.37‑1.67)

1.76 (1.59‑1.94)

2.11 (1.90‑2.33)

2.40 (2.15‑2.65)

2.70 (2.40‑2.98)

3.02 (2.67‑3.34)

3.48 (3.04‑3.90)

3.84 (3.33‑4.59)

2-day 1.09 (0.989‑1.21)

1.36 (1.23‑1.50)

1.68 (1.52‑1.85)

1.95 (1.76‑2.14)

2.32 (2.10‑2.55)

2.62 (2.35‑2.87)

2.93 (2.62‑3.22)

3.26 (2.89‑3.58)

3.71 (3.26‑4.08)

4.07 (3.54‑4.64)

3-day 1.17 (1.07‑1.29)

1.45 (1.32‑1.60)

1.80 (1.64‑1.97)

2.08 (1.89‑2.28)

2.47 (2.24‑2.69)

2.77 (2.50‑3.03)

3.09 (2.77‑3.38)

3.42 (3.05‑3.74)

3.87 (3.42‑4.25)

4.23 (3.70‑4.72)

4-day 1.25 (1.14‑1.37)

1.55 (1.42‑1.69)

1.91 (1.75‑2.09)

2.21 (2.01‑2.40)

2.61 (2.37‑2.84)

2.93 (2.65‑3.18)

3.25 (2.93‑3.54)

3.59 (3.21‑3.91)

4.04 (3.58‑4.41)

4.39 (3.86‑4.81)

7-day 1.45 (1.35‑1.57)

1.80 (1.67‑1.95)

2.21 (2.05‑2.39)

2.54 (2.36‑2.74)

3.00 (2.77‑3.23)

3.36 (3.09‑3.61)

3.73 (3.41‑4.00)

4.10 (3.73‑4.41)

4.61 (4.16‑4.97)

5.00 (4.48‑5.40)

10-day 1.61 (1.49‑1.74)

2.00 (1.85‑2.17)

2.45 (2.27‑2.65)

2.81 (2.59‑3.03)

3.29 (3.03‑3.54)

3.65 (3.36‑3.94)

4.03 (3.69‑4.34)

4.39 (4.00‑4.75)

4.89 (4.42‑5.29)

5.25 (4.73‑5.71)

20-day 2.09 (1.93‑2.26)

2.59 (2.39‑2.81)

3.16 (2.92‑3.41)

3.60 (3.32‑3.88)

4.17 (3.84‑4.50)

4.60 (4.22‑4.96)

5.02 (4.60‑5.42)

5.44 (4.96‑5.88)

5.97 (5.42‑6.47)

6.35 (5.74‑6.91)

30-day 2.55 (2.36‑2.75)

3.16 (2.92‑3.41)

3.81 (3.52‑4.10)

4.30 (3.97‑4.63)

4.94 (4.56‑5.31)

5.40 (4.97‑5.80)

5.84 (5.37‑6.28)

6.27 (5.76‑6.75)

6.80 (6.23‑7.33)

7.18 (6.56‑7.76)

45-day 3.25 (3.00‑3.51)

4.03 (3.72‑4.35)

4.84 (4.47‑5.22)

5.45 (5.03‑5.86)

6.22 (5.74‑6.68)

6.76 (6.24‑7.26)

7.28 (6.71‑7.82)

7.76 (7.14‑8.33)

8.33 (7.66‑8.95)

8.72 (8.01‑9.37)

60-day 3.84 (3.54‑4.16)

4.74 (4.37‑5.14)

5.66 (5.22‑6.11)

6.32 (5.82‑6.82)

7.13 (6.57‑7.69)

7.69 (7.08‑8.30)

8.22 (7.56‑8.86)

8.69 (7.99‑9.38)

9.23 (8.48‑9.97)

9.59 (8.81‑10.4)

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 https://www.commerce.gov/ http://www.noaa.gov/ https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.9366&lon=-109.7718&data=depth&units=english&series=pds 2/4

Back to Top

Maps & aerials

Small scale terrain https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.9366&lon=-109.7718&data=depth&units=english&series=pds 3/4

Large scale terrain

Large scale map

Large scale aerial

3km

2mi

100km

60mi

100km

60mi https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.9366&lon=-109.7718&data=depth&units=english&series=pds 4/4

Back to Top

US Department of Commerce National Oceanic and Atmospheric Administration

National Weather Service National Water Center

1325 East West Highway Silver Spring, MD 20910

Questions?: HDSC.Questions@noaa.gov

Disclaimer

100km

60mi https://www.commerce.gov/ http://www.noaa.gov/ http://www.nws.noaa.gov/ http://www.nws.noaa.gov/oh/ mailto:HDSC.Questions@noaa.gov http://www.nws.noaa.gov/disclaimer.html

5/16/2019 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.9373&lon=-109.7661&data=intensity&units=english&series=pds 1/4

NOAA Atlas 14, Volume 1, Version 5 Location name: Manila, Utah, USA*

Latitude: 40.9373°, Longitude: -109.7661° Elevation: 6580.55 ft**

* source: ESRI Maps ** source: USGS

POINT PRECIPITATION FREQUENCY ESTIMATES

Sanja Perica, Sarah Dietz, Sarah Heim, Lillian Hiner, Kazungu Maitaria, Deborah Martin, Sandra Pavlovic, Ishani Roy, Carl Trypaluk, Dale Unruh, Fenglin Yan, Michael Yekta, Tan Zhao, Geoffrey

Bonnin, Daniel Brewer, Li-Chuan Chen, Tye Parzybok, John Yarchoan

NOAA, National Weather Service, Silver Spring, Maryland

PF_tabular | PF_graphical | Maps_&_aerials

PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1

Duration Average recurrence interval (years)

1 2 5 10 25 50 100 200 500 1000

5-min 1.43 (1.24‑1.69)

1.85 (1.58‑2.18)

2.54 (2.17‑3.01)

3.17 (2.69‑3.74)

4.16 (3.44‑4.93)

5.05 (4.08‑6.04)

6.08 (4.79‑7.36)

7.31 (5.54‑8.96)

9.23 (6.65‑11.6)

11.0 (7.61‑14.1)

10-min 1.09 (0.942‑1.28)

1.40 (1.21‑1.67)

1.93 (1.65‑2.29)

2.41 (2.04‑2.84)

3.16 (2.62‑3.75)

3.84 (3.11‑4.59)

4.63 (3.64‑5.60)

5.56 (4.21‑6.83)

7.03 (5.06‑8.83)

8.36 (5.78‑10.7)

15-min 0.900 (0.780‑1.06)

1.16 (1.00‑1.38)

1.60 (1.37‑1.89)

1.99 (1.69‑2.35)

2.62 (2.16‑3.10)

3.18 (2.57‑3.79)

3.83 (3.01‑4.63)

4.59 (3.48‑5.64)

5.80 (4.18‑7.30)

6.91 (4.78‑8.87)

30-min 0.606 (0.524‑0.716)

0.782 (0.674‑0.928)

1.08 (0.920‑1.27)

1.34 (1.14‑1.58)

1.76 (1.46‑2.09)

2.14 (1.73‑2.55)

2.58 (2.03‑3.12)

3.09 (2.35‑3.80)

3.91 (2.82‑4.91)

4.65 (3.22‑5.97)

60-min 0.374 (0.324‑0.442)

0.483 (0.416‑0.574)

0.665 (0.569‑0.788)

0.830 (0.703‑0.980)

1.09 (0.901‑1.29)

1.32 (1.07‑1.58)

1.60 (1.25‑1.93)

1.91 (1.45‑2.35)

2.42 (1.74‑3.04)

2.88 (1.99‑3.70)

2-hr 0.234 (0.206‑0.272)

0.296 (0.258‑0.343)

0.396 (0.344‑0.458)

0.485 (0.417‑0.562)

0.630 (0.530‑0.732)

0.763 (0.626‑0.892)

0.920 (0.733‑1.09)

1.11 (0.851‑1.33)

1.41 (1.03‑1.73)

1.68 (1.18‑2.12)

3-hr 0.177 (0.156‑0.204)

0.223 (0.197‑0.256)

0.292 (0.256‑0.336)

0.354 (0.307‑0.406)

0.451 (0.384‑0.520)

0.536 (0.446‑0.622)

0.638 (0.517‑0.749)

0.757 (0.596‑0.903)

0.955 (0.721‑1.17)

1.14 (0.826‑1.42)

6-hr 0.113 (0.101‑0.128)

0.141 (0.126‑0.161)

0.180 (0.159‑0.204)

0.213 (0.187‑0.242)

0.262 (0.226‑0.298)

0.301 (0.257‑0.344)

0.347 (0.290‑0.400)

0.402 (0.329‑0.471)

0.497 (0.394‑0.593)

0.583 (0.450‑0.719)

12-hr 0.068 (0.061‑0.076)

0.084 (0.076‑0.095)

0.106 (0.094‑0.118)

0.124 (0.110‑0.139)

0.150 (0.132‑0.169)

0.172 (0.149‑0.196)

0.197 (0.166‑0.225)

0.222 (0.184‑0.258)

0.268 (0.216‑0.319)

0.310 (0.242‑0.376)

24-hr 0.040 (0.037‑0.045)

0.050 (0.046‑0.056)

0.063 (0.057‑0.069)

0.073 (0.066‑0.081)

0.088 (0.079‑0.097)

0.099 (0.089‑0.110)

0.112 (0.100‑0.124)

0.125 (0.111‑0.138)

0.144 (0.126‑0.162)

0.159 (0.138‑0.190)

2-day 0.023 (0.021‑0.025)

0.028 (0.026‑0.031)

0.035 (0.032‑0.038)

0.040 (0.037‑0.044)

0.048 (0.043‑0.053)

0.054 (0.049‑0.059)

0.061 (0.054‑0.067)

0.067 (0.060‑0.074)

0.077 (0.067‑0.084)

0.084 (0.073‑0.096)

3-day 0.016 (0.015‑0.018)

0.020 (0.018‑0.022)

0.025 (0.023‑0.027)

0.029 (0.026‑0.031)

0.034 (0.031‑0.037)

0.038 (0.035‑0.042)

0.043 (0.038‑0.047)

0.047 (0.042‑0.052)

0.053 (0.047‑0.058)

0.058 (0.051‑0.065)

4-day 0.013 (0.012‑0.014)

0.016 (0.015‑0.018)

0.020 (0.018‑0.022)

0.023 (0.021‑0.025)

0.027 (0.025‑0.029)

0.030 (0.027‑0.033)

0.034 (0.030‑0.037)

0.037 (0.033‑0.040)

0.042 (0.037‑0.046)

0.045 (0.040‑0.050)

7-day 0.009 (0.008‑0.009)

0.011 (0.010‑0.012)

0.013 (0.012‑0.014)

0.015 (0.014‑0.016)

0.018 (0.016‑0.019)

0.020 (0.018‑0.021)

0.022 (0.020‑0.024)

0.024 (0.022‑0.026)

0.027 (0.025‑0.029)

0.029 (0.026‑0.032)

10-day 0.007 (0.006‑0.007)

0.008 (0.008‑0.009)

0.010 (0.009‑0.011)

0.012 (0.011‑0.012)

0.014 (0.013‑0.015)

0.015 (0.014‑0.016)

0.017 (0.015‑0.018)

0.018 (0.017‑0.020)

0.020 (0.018‑0.022)

0.022 (0.020‑0.024)

20-day 0.004 (0.004‑0.005)

0.005 (0.005‑0.006)

0.007 (0.006‑0.007)

0.007 (0.007‑0.008)

0.009 (0.008‑0.009)

0.009 (0.009‑0.010)

0.010 (0.009‑0.011)

0.011 (0.010‑0.012)

0.012 (0.011‑0.013)

0.013 (0.012‑0.014)

30-day 0.003 (0.003‑0.004)

0.004 (0.004‑0.005)

0.005 (0.005‑0.006)

0.006 (0.005‑0.006)

0.007 (0.006‑0.007)

0.007 (0.007‑0.008)

0.008 (0.007‑0.009)

0.009 (0.008‑0.009)

0.009 (0.009‑0.010)

0.010 (0.009‑0.011)

45-day 0.003 (0.003‑0.003)

0.004 (0.003‑0.004)

0.004 (0.004‑0.005)

0.005 (0.005‑0.005)

0.006 (0.005‑0.006)

0.006 (0.006‑0.007)

0.007 (0.006‑0.007)

0.007 (0.007‑0.008)

0.008 (0.007‑0.008)

0.008 (0.007‑0.009)

60-day 0.003 (0.002‑0.003)

0.003 (0.003‑0.004)

0.004 (0.004‑0.004)

0.004 (0.004‑0.005)

0.005 (0.005‑0.005)

0.005 (0.005‑0.006)

0.006 (0.005‑0.006)

0.006 (0.005‑0.006)

0.006 (0.006‑0.007)

0.007 (0.006‑0.007)

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.