NV FLAP US93(1)_100 Drainage Memo.pdf

CFLHD | NV_FLAP_US93(1)

Memo hdrinc.com 1670 Broadway Suite 3400 Denver, CO 80202-4824

(303) 764-1520

Date: Thursday, May 21, 2020

Project: NV FLAP US93(1) Pahranagat National Wildlife Refuge, Lincoln County, Nevada

To: Emilio Burgos, CFLHD

From: Colleen Koenig, HDR

Subject: Final Hydrology and Hydraulics Design

Introduction

This memo summarizes the hydrologic and hydraulic analyses performed for the Nevada

Federal Lands Access Program (FLAP) Pahranagat National Wildlife Refuge (NWR) (Refuge)

Contract number DTFH681-16-D-00006/6982AF19F000029.

The project is located in Lincoln County, Nevada, approximately 90 miles northeast of Las

Vegas. The Refuge is accessed from US 93. The purpose of the project is to provide improved safety at two intersections by designing and constructing acceleration and deceleration lanes and turn pockets along US 93. There are two proposed locations for turn lanes; at the Refuge visitor center access road and the Refuge campground access road. Lanes will be widened off of the existing edge of traveled way and the through lane will be shifted in order to provide a center left turn lane. A portion of the existing trail east of the visitor center entrance will be relocated to accommodate widening. Drainage work will include the extension of existing culverts, replacement and realignment of impaired culvert, replacement of water control structures, and improve passage for desert tortoises through culverts. Drainage improvements will take place as needed along US 93 to accommodate the roadway widening and roadside ditch improvements.

The drainage design for this project was prepared in accordance with Federal Lands Highway

“Project Development and Design Manual” (PDDM), Chapter 7 Hydrology and Hydraulics, December 2012 as well as the Nevada Department of Transportation “Drainage Manual” (DM)

December 2006.

Criteria

Partner Agencies for the project include Nevada Department of Transportation (NDOT), US Fish and Wildlife Service (USFWS) and Lincoln County. US 93 is classified as a Rural Principal

Arterial and is owned and maintained by NDOT. Access roads will be classified as Local or

Frontage Roads and owned and maintained by USFWS. Drainage criteria follows the design standards in the DM Tables 3-1 and 3-2 for Other Principal Arterial and Frontage Roads for US

93 and Access Roads respectively. Project applicable criteria is outlined below in Table 1. A criteria matrix is included in Appendix A.

6/31/21

08/26/2020

Table 1 Hydrology & Hydraulic Criteria

Design Feature PDDM/DM Criteria

Peak Flow Methods Rational Method : Areas up to 200 acres Regression Equations : areas over 200 acres

Culverts

Capacity Arterial : 25-year Frontage/Local : 10-year 100-year analyze impacts outside of ROW

Headwater (HW) Elevation Existing WSEL < shoulder hinge point

Headwater/Depth Ratio (HW/D) 48” diameter or smaller = 1.5 >48” diameter 1.2

Minimum Size Parallel Culvert 18” or equivalent Cross Culvert 24” or equivalent

Pipe Material Minimum : Reinforced Concrete Pipe III (RCP) or 0.064” (1.63 mm) CMP

End Treatments End Sections or Headwalls, NDOT R-2.1.1

Outlet Protection Velocities up to 12 fps : Riprap apron Velocities > 12 fps Energy Dissipators

Roadside Ditches

Capacity Arterial : 25-year Frontage/Local : 10-year 100-year analyze impacts outside of ROW

Depth Depth ≤ shoulder hinge point

Minimum Slope Minimum slope 0.5%

Freeboard 0.5 feet

Ditch Stability

Permanent Lining Arterial : 25-year Frontage/Local : 10-year

Temporary Lining 2-year flood

Inlets

Capacity Arterial : 25-year

Clogging Factor On-grade with anticipated debris 25% In-sag 50% - orifice condition ½ of surface is clogged

Manholes

Minimum drop 0.1 foot

Minimum separation between pipe penetrations 6 inches

Maximum spacing 24” or less : 300 feet 24” or greater : 400 feet

Hydrology

Hydrology was developed to assess the roadside ditches only. Cut ditches were added through a portion of the project, in other sections fill slopes reduced the ditch capacity or pushed the toe further to the east through sections where there is no formalized ditch or flows away from US

93. Hydrology was developed to confirm hydraulics through these sections. Basin Maps and hydrologic calculations are included in Appendix B. Hydrology was not developed for the culvert crossings due large contributing basins. Hydrologic analysis for the contributing areas would require additional mapping and in-depth analysis which is out of the project scope. No significant increase in runoff is anticipated due to the increased imperviousness area of the proposed roadway being minimal in relation the contributing basin area. The Arizona

Department of Transportation Highway Drainage Design Manual was used to determine the runoff coefficient for the 10-yr (design) storm based on CFLHD recommendations.

Table 2 Hydrologic Summary

Basin ID Area

(acres) C10

Peak Flow

Q-10 (cfs) C25

Peak Flow

Q-25 (cfs)

B110 2.45 0.35 2.22 0.38 3.13

B125 0.79 0.48 0.98 0.51 1.37

B131 1.53 0.47 1.83 0.49 2.54

B135 7.54 0.29 5.67 0.32 8.15

B205 0.79 0.25 0.51 0.28 0.74

B209 1.58 0.25 1.00 0.28 1.47

B210 2.88 0.25 1.84 0.28 2.69

B216 0.12 0.25 0.08 0.28 0.11

B217 0.94 0.25 0.60 0.28 0.88

B220 0.41 0.25 0.26 0.28 0.38

B221 8.42 0.32 6.46 0.35 9.19

B222 2.77 0.29 1.99 0.31 2.87

B233 0.43 0.40 0.44 0.42 0.62

B234 9.37 0.29 6.32 0.31 9.11

Hydraulics

Culverts

Culverts along the project were not evaluated for capacity. Existing culverts will be extended to match the flow line of proposed fill slopes, with the exception of the culvert at STA 124+76 which will be replaced and realigned. Table 3 lists culverts along the project. Existing culverts are all corrugated metal pipe (CMP).

The following description of culverts will have additional work. Culvert station designation is at the centerline of US 93 and culvert intersection.

The culvert at station 124+76 that drains from the trail head parking into the refuge has been coordinated with the Refuge. In the field it was discovered that the existing culvert was in poor condition with a 12” PVC slip liner inside of the 21” CMP. Since the functionality of the pipe is impaired, it is proposed as being replaced with a new 21” CMP with a manhole and additional downstream pipe discharging into the refuge pond. There is an existing water control structure at the upstream end of the pipe that is being impacted by the proposed design. This control structure will be removed and replaced with a NRCS flashboard riser at the upstream end of the pipe. Currently there is also a control structure downstream of the existing outfall. The refuge no longer uses this structure and it will be removed. The culvert will be extended with minor grading and outlet protection at the outfall.

The visitor center entrance road will be realigned. The new alignment will cross existing culverts at two locations. The dual culverts located at station 300+88/300+95 are also connected to a control structure. These will not be impacted.

The next location is at station 301+64. This culvert also has an inlet structure. Both will be removed with minor grading to direct flows to the culverts at station 300+83/300+95.

Two culvert extensions, located at station 117+04 and 220+08 require extension into the east embankment requiring additional cut, but matches existing conditions. Riprap was added to

117+04 and geomembrane and grading is proposed at 220+08.

The roadside ditch from 221+44 to 233+07 drains to the driveway at 222+66. In existing conditions runoff drains across the road. A cut ditch is proposed, therefore an inlet will be added to drain the ditch flows. This will drain to culvert 220+08. Inlet capacity was estimated using

HEC22 Equation 4-2 Qi=C0Ag(2gd)0.5 where C0 = orifice coefficient =0.67, Ag = clear opening area of the grate in square feet (ft2) and g is acceleration due to gravity 32.16 ft/s2. FHWA

Standard Detail, 604-1, Catch Basin Type 1 with metal frame and grate Type A, Standard Detail

604-2. Inlet capacity was determined to be 12 cfs. NDOT recommends a 50% clogging factor for inlets in sag and in orifice condition. Therefore, the inlet capacity is 6 cfs. Flow to the inlet is 10 cfs and two inlets will be required to capture the design (Q25) flow.

No culvert end treatments were identified on the survey. Flared end sections have been added where appropriate. Where work is not being done or the culvert invert is elevated from the channel invert, end treatments will not be added. Riprap or geomembrane outlet protection is proposed on culverts that have downstream culvert extensions. Culvert stations listed in the

Table are based on the intersection of the culvert at the roadway centerline.

Table 3 Culvert Summary

Culvert

Station

Pipe Diameter

(inches) Material Proposed Work

117+04 71”x47” Arch CMP Extend U/S

124+77 21” CMP Replace and Extend D/S

131+20 18” CMP Extend U/S

209+47 24” CMP Extend U/S

216+36 36” CMP Extend U/S

220+86 18” CMP Extend U/S

222+66 18” CMP Inlet and new d/s culvert

233+18 18” CMP Extend U/S

300+88/300+95 2 – 36” CPP No impact

301+64 24” CMP Remove

Roadside Ditches

Ditch hydraulics were analyzed as they have been impacted by the widening and extended slope or new ditches have been cut in areas where the limits extend into the back slope. Ditch hydraulics were evaluated using Bentley FlowMaster for the 25-year peak discharge following

NDOT DM.

The proposed widening through the visitor center and camp ground transition between cut and fill. Fill areas through some sections reduce the existing ditch capacity. In some locations fill limits push the flow line out on a non-formalized ditch. The cut sections will match existing geometry or improve the current conditions with the addition of a ditch. In cut sections, proposed

V ditches with 2.5H:1V or 3H:1V are proposed. Riprap will be placed between the cut and fill transitions following Federal Highway Administration (FHWA) Central Federal Lands Highway

Division (CFLHD) Standard Detail C251-51.

Between stations 124+00 and 128+00 the fill slope impacts the existing trail. The trail will be realigned to the east.

Table 4 summarizes ditch sections that have been modified and have been evaluated to confirm the proposed conditions meet design criteria. Cut ditch section 234+67 to 236+12 right exceeds the allowable depth. Cut ditches matched the existing geometry. Additional impacts would be required to increase the depth of the ditch.

Table 4 Ditch Summary

Station Condition Q25

(cfs) Geometry

Allowable

Depth (feet)

Design Depth

(feet)

109+55 to 110+30 Rt. Cut 3.1 V 1.5 0.6

110+30 to 111+45 Rt. Fill 3.1 V 1.9 0.6

111+45 to 115+95 Rt. Cut 3.1 V 1.5 0.6

115+95 to 116+80 Rt Fill - Toe adjusted, no formal ditch

117+35 to 122+55 Rt. Fill - Toe adjusted, no formal ditch

117+45 to 122+55 Lt. Fill - Toe adjusted, no formal ditch

123+10 to 124+80 Rt. Fill - Toe adjusted, no formal ditch

123+17 to 128+65 Lt. Fill - Toe adjusted, no formal ditch

124+90 to 131+30 Rt. Fill 2.5 V 5 0.8

131+75 to 134+45 Rt. Fill 0.8 V 8.5 0.3

135+20 to 138+16 Rt. Fill - Toe adjusted, no formal ditch

205+72 to 207+44 Rt. Fill 0.7 V 2.5 0.4

207+44 to 209+37 Rt. Fill 1.5 V 10.5 0.4

209+52 to 215+27 Rt. Fill 2.7

Multiple sections

V, Trap and un-formalized

9.5 0.5

216+47 to 219+58 Rt. Fill 0.9 V and un-formalized

9.5 0.3

217+50 to 222+20 Lt. Fill - Toe adjusted, no formal ditch

219+58 to 220+72 Rt. Cut 0.4 V 1.5 0.3

222+65 to 231+47 Rt. Cut 9.2 V 1.5 *1.1

233+37 to 234+67 Rt. Fill 9.2 V 1 *1.1

223+12 to 227+47 Lt. Cut 2.9 V 1.5 0.6

234+67 to 236+12 Rt. Cut 9.1 V 1 *1.5

Notes: Allowable depth is distance from flow line of ditch to edge of shoulder.

*Exceeds minimum design criteria.

Outlet Protection and Slope Stabilization

For the northern portion of the project from STA 204+59 - STA 236+19 there was concern about the ability for desert tortoises to be able to use the culverts as passageways to cross US 93.

Based on discussions with environmental staff riprap and steep slopes prevent tortoise crossing. As an alternative to riprap, a cellular confinement system (geomembrane) slope stabilization and proposed 6:1 grading at the upstream and downstream side is proposed at areas of concern. Riprap is proposed at the southern portion of the project where there has been no desert tortoises reported. The geomembrane apron was sized based on manufacturers recommendations based on outlet velocity and slope and have been included in Appendix for reference. See summary table below for proposed dimensions.

Geotextile Apron Sizing

Reference: FHWA HEC14 Hydraulic Design of Energy Dissipaters for Culverts and

Channels Ch.10

Feature

Culvert

Dia. (ft)

Design

Discharge

Length

(FT)

Width at

Outlet (FT)

Width at End

Rock Infill

Size

Culvert 209+47 2.0 28.6 11.2 6.0 9.8 4”

Culvert 216+36 3.0 70.1 15.2 9.0 14.1 4”

Culvert 220+86 3.5 95.8 17.2 10.5 16.3 4”

Culvert 233+18 2.0 24.4 11.2 6.0 9.8 4”

Visitor Center Parking Area

The current parking area for the Pahranagat National Wildlife Refuge is a gravel lot with a depressed area in the center. The proposed improvements for the parking area include paving, signing, and striping to improve the flow of traffic and provide additional parking for cars and trailers.

To account for the additional runoff due to paving, the depressed center area was analyzed to determine if there was adequate capacity to detain flows without flooding the parking area. The depressed area was analyzed for volume as a pond using the Mile High Flood District (MHFD)

Detention, Version 4.02. The volume of runoff draining to the pond was calculated to be 0.088 ac-ft. The existing pond was evaluated and determined to have 0.017 ac-ft of storage, which would result in flooding in storm events exceeding the 2-yr storm.

Grading within the pond has been proposed in order to increase capacity and mitigate flooding.

The proposed grading of the pond was analyzed and determined to provide 0.097 ac-ft, which would provide the necessary volume to capture the 100-yr storm event without flooding. MHFD-

Detention Calculations for the existing and proposed ponds have been attached in Appendix C.

Sediment and Erosion Control

Sediment and erosion control will follow NDOT Guidelines in 2013 Stormwater Management

Program, Construction Site Best Management Practices (BMPs) Manual and the Nevada

Contractors Field Guide for Construction Site Best Management Practices. A Nevada

Department of Environmental Protection (NDEP) SWPP has also been prepared detailing stormwater discharge and management. Fiber rolls will be placed at the toe of fill, across contours on long slopes, as ditch checks and around culvert entrance and exits. Fiber rolls shall be placed on long slopes of 15 feet or less. Side slopes within the project are between 4H:1V and 2H:1V. Ditch checks will be placed at intervals based on the following table.

Table 5 Ditch Check Spacing

Ditch Slope Check

Spacing (feet)

5% 55

3% 100

2% 150

1% 300

0.5% 600

Project Summary and Intent

The main objective of the drainage component of this project is to perpetuate existing drainage patterns by updating drainage to be compatible with the new roadway design and improving functionality. The design will also incorporate environmental improvements by updating existing culverts to allow desert tortoises to be able to use them as passageways under US 93.

CFLHD | NV FLAP US93(1)

Preliminary Hydraulics Memo

1670 Broadway , Suite 3400 , Denver , CO 80202-4824 hdrinc.com

Appendix A Criteria Matrix

Criteria FHWA NDOT Recommendations

Road Classification

Hydrology

Peak runoff calculation

Rational Method up to 200 acres Rational Method up to 200 acres Rational Method up to 200 acres

STORM DRAINS

Design Frequency

Minor (on-grade) 10 25 25

Sump (low points) 50 25 25

SURFACE FLOW

Design Frequency 10 25 25

PIPES

Minimum Size 15 inch or equivalent 18" trunkline, 15" lateral 18"

Pipe Hydraulic Criteria full flow (no pressure) for the design event wherever possible hydraulic gradeline for the design flood below ground elevation at all inlets and access structures

Minimum Velocity 3 fps flowing full 3 fps for design flow 3 fps for design flow

Maximum Velocity compatible with the erosion characteristics of the outlet channel bed and bank material - HEC14 compatible with the erosion characteristics of the outlet channel bed and bank material - HEC14

Minimum Slope 0.50% 0.30%

Tailwater Conditions HEC 22

Manholes

Pipe Size Maximum Spacing

15-24 inch 300 feet

27-36 inch 400 feet

42-54 inch 600 feet

60 and up 1000 feet

24" or less 300 feet

24" or greater 400 feet

24" or less 300 feet

24" or greater 400 feet

Outlet Treatment headwall/wingwall where applicable stable for the design discharge

Culverts

Design Frequency

High Standard 50-year flood, temp detour 10-year

Low Standard 25-year flood, temp detour 2-year

Roadside ditches 10-year for both high & low standard roads

Arterial : 25-year

Frontage Roads : 10-year

100-year must be analyzed for existing and future condtions.

Mitigation must be provided if the 100-year flow conditions within or outside of NDOT ROW are unreasonably aggravated.

Arterial : 25-year

Frontage Roads : 10-year

100-year must be analyzed for existing and future condtions.

Mitigation must be provided if the 100-year flow conditions within or outside of NDOT ROW are unreasonably aggravated.

Headwater Elevation

New culverts: headwater (HW) no greater than the shoulder hinge point a the local roadway low point.

Ponding not allowed to spread onto the shoulder of the roadway) for design flow should not exceed edge of roadway pavement, but should not exceed HW/D of 1.5 for design flow should not exceed edge of roadway pavement, but should not exceed HW/D of 1.5

Existing Culverts: HW elevation will not be greater than the shoulder hinge point at the local roadway low point (ponding not allowed to spread onto the shoulder of the roadway)

Existing Culverts: HW elevation will not be greater than the shoulder hinge point at the local roadway low point

(ponding not allowed to spread onto the shoulder of the roadway)

HW/D Ratio 48" equivalent and smaller 1.5 1.5 48" equivalent and smaller 1.5

>48" equivalent culverts 1.2 1.5 >48" equivalent culverts 1.2

Debris or Sediment: 0.8-1.0 depending on severity where potential for heavy debris or sediment bed loads are a concern

Debris or Sediment: 0.8-1.0 depending on severity where potential for heavy debris or sediment bed loads are a concern

Material dependent on site

MIN : RCP Class II min or 0.064" (1.63mm) Metal dependent on site

MIN : RCP Class II min or 0.064" (1.63mm) Metal

Maximum Velocity compatible with the erosion characteristics of the outlet channel bed and bank material - HEC14 12 fps 12 fps

Minimim Diameter cross-raod culvert : 24-inch parallel culvert : 18-inch

24-inch on interstate systems

18-inch elsewhere 24-inch on interstate systems18-inch elsewhere

Skew culvert skew from a line perpendicular to the roadway centerline shall not exceed 45 degrees culvert skew from a line perpendicular to the roadway centerline shall not exceed 45 degrees

Outlet Protection HEC14 use of riprap should be considered for all culverts with erosive outlet velocities riprap aprons for velocities up to 12 fps

Energy dissipators for velocities >12 fps

HEC-11 or HEC-14 use of riprap should be considered for all culverts with erosive outlet velocities riprap aprons for velocities up to 12 fps

Energy dissipators for velocities >12 fps

HEC-11 or HEC-14

Debris racks and Grates should be considered in areas with high debris load, long culverts, culverts present an "attractive nuisance" should be considered in areas with high debris load, long culverts, culverts present an "attractive nuisance"

End Treatments end sections or HW

NDOT R-2.1.1

end sec?ons or HWNDOT R-2.1.1

ROADSIDE DITCHES

Design Frequency 10-year

HEC15

Arterial : 25-year

Frontage Roads : 10-year

100-year should also be analysed, mitigation must be provided if 100-year flow conditions within or outside of

NDOT ROW are unreasonably aggravated

100-year

Arterial : 25-year

Frontage Roads : 10-year

100-year should also be analysed, mitigation must be provided if 100-year flow conditions within or outside of NDOT ROW are unreasonably aggravated

100-year

Stability Design 10-year

HEC15

stable for design storm

HEC-15

stable for design stormHEC-15

Temproary Lining 2 2

Maximum side slope Earthen channel 3:1 or flatter

Riprap-lined channel 2:1 or flatter

Earthen channel 3:1 or flatter

Riprap-lined channel 2:1 or flatter

Maximum velocity check permissible shear stress 0

Freeboard 0 to 1 foot based upon engineering judgement 0 to 1 foot based upon engineering judgement

Depth New - bottom of aggregate base layer

Existing - shoulder hinge point of roadway

New - bottom of aggregate base layer

Existing - shoulder hinge point of roadway

Minimum slope % 0.50% 0.50%

US93 : Rural Principla Arterial

Summary of Roadway Drainage Criteria

Access Roads, Visitor Center, Campground : Local/Frontage Road

Pahranagat NWR Access NV FLAP US93(1)

Design Criteria Matrix

Appendix B Hydrology

Rational Method

Runoff Coefficients Project: NV FLAP US93(1) Pahranagat NWR Access Computed: AJF Date: 8/8/2019

System Name: Visitor Center Entrance, Campground Entrance Checked: EVS Date: 9/24/2019

Sub-Basin Data

Basin ID Description

Total Area

(ac)

B110 109+48 to 116+42 RT 2.45 0.35 0.25 0.40 0.90 0.38 0.28 0.44 0.91 0.57 0.50 0.50 0.93 D 15.9% 2.06 0.00 0.39

B125 122+83 to 124+64 RT 0.79 0.48 0.25 0.40 0.90 0.51 0.28 0.44 0.91 0.60 0.50 0.50 0.93 A 34.2% 0.20 0.40 0.19

B131 124+64 to 131+41 RT 1.53 0.47 0.25 0.40 0.90 0.49 0.28 0.44 0.91 0.64 0.50 0.50 0.93 C 33.7% 0.95 0.08 0.50

B132 131+46 to 134+80 RT 0.42 0.51 0.25 0.40 0.90 0.53 0.28 0.44 0.91 0.67 0.50 0.50 0.93 B 40.5% 0.25 0.00 0.17

B135 135+16 to 146+ RT 7.54 0.29 0.25 0.40 0.90 0.32 0.28 0.44 0.91 0.53 0.50 0.50 0.93 D 6.7% 6.95 0.11 0.48

B205 204+82 TO 207+45 RT 0.79 0.25 0.25 0.40 0.90 0.28 0.28 0.44 0.91 0.50 0.50 0.50 0.93 D 0.0% 0.79 0.00 0.00

B209 207+45 to 209+37 RT 1.58 0.25 0.25 0.40 0.90 0.28 0.28 0.44 0.91 0.50 0.50 0.50 0.93 D 0.0% 1.58 0.00 0.00

B210 209+52 to 215+27 RT 2.88 0.25 0.25 0.40 0.90 0.28 0.28 0.44 0.91 0.50 0.50 0.50 0.93 D 0.0% 2.88 0.00 0.00

B216 215+27 to 216+26 RT 0.12 0.25 0.25 0.40 0.90 0.28 0.28 0.44 0.91 0.50 0.50 0.50 0.93 A 0.0% 0.12 0.00 0.00

B217 216+46 to 219+58 RT 0.94 0.25 0.25 0.40 0.90 0.28 0.28 0.44 0.91 0.50 0.50 0.50 0.93 D 0.0% 0.94 0.00 0.00

B220 219+58 to 220+82 RT 0.41 0.25 0.25 0.40 0.90 0.28 0.28 0.44 0.91 0.50 0.50 0.50 0.93 D 0.0% 0.41 0.00 0.00

B221 221+37 to 231+81 RT 8.42 0.32 0.25 0.40 0.90 0.35 0.28 0.44 0.91 0.55 0.50 0.50 0.93 D 11.5% 7.45 0.00 0.97

B222 223+17 to 233+12 LT 2.77 0.29 0.25 0.40 0.90 0.31 0.28 0.44 0.91 0.52 0.50 0.50 0.93 D 5.4% 2.62 0.00 0.15

B233 231+81 to 233+12 RT 0.43 0.40 0.25 0.40 0.90 0.42 0.28 0.44 0.91 0.60 0.50 0.50 0.93 D 23.3% 0.33 0.00 0.10

B234 233+36 to 241+85 RT 9.37 0.29 0.25 0.40 0.90 0.31 0.28 0.44 0.91 0.52 0.50 0.50 0.93 D 5.4% 8.86 0.00 0.51

B290 290+00 - 295+00 RT 2.75 0.25 0.25 0.40 0.90 0.28 0.28 0.44 0.91 0.50 0.50 0.50 0.93 D 0.0% 2.75 0.00 0.00

C25

ImPervious

Areas

Visitor Center

Campground

Notes:

Composite

C10

C10

Pervious

Areas

C10

ImPervious

Areas

Composite

C25

C25

Pervious

Areas

**C25 determined from HEC22 Urban Drainage Design Manual

C10

Gravel Areas

C100

Gravel Areas

C25

Gravel Areas

Composite

C100

*C values determined from Arizona Department of Transportation Highway Drainage Design Manual, Figure 2-1 for the 10-yr Storm

Vistor Center Road

C100

Pervious

Areas

C100

ImPervious

Areas

Hydrologic

Soils Group

Percent

Impervious

Area Pervious

(ac)

Area

Impervious (ac)Gravel (ac)

Standard Form SF-1 . Time of Concentration Project: NV FLAP US93(1) Pahranagat NWR Access AJF 8/8/2019

System Name: Visitor Center Entrance, Campground Entrance EVS 9/24/2019

SUB-BASIN DATA INITIAL/OVERLAND FLOW TRAVEL TIME

(ti) (tt)

B110 109+48 to 116+42 RT 0.90 0.16 2.45 65 3.8 1.85 634 1.4 0.732 2.9 3.70 5.55 10.00

B125 122+83 to 124+64 RT 0.40 0.91 0.79 25 2.0 5.00 624 39.4 0.732 15.1 0.69 5.69 10.00

B131 124+64 to 131+41 RT 0.90 0.91 1.53 57 15.8 1.08 634 0.2 0.732 1.2 9.05 10.14 10.14

B132 131+46 to 134+80 RT 0.25 0.91 0.42 48 8.7 5.14 283 2.0 0.732 3.4 1.40 6.54 10.00

B135 135+16 to 146+ RT 0.29 0.91 7.54 37 2.0 7.01 1317 14.9 0.732 9.3 2.37 9.38 10.00

B205 204+82 TO 207+45 RT 0.25 0.91 0.79 100 15.0 6.20 382 7.6 0.732 6.6 0.96 7.17 10.00

B209 207+45 to 209+37 RT 0.25 0.91 1.58 100 5.0 8.95 544 9.0 0.732 7.2 1.26 10.21 10.21

B210 209+52 to 215+27 RT 0.25 0.91 2.88 100 14.0 6.35 912 11.3 0.732 8.1 1.88 8.23 10.00

B216 215+27 to 216+26 RT 0.25 0.91 0.12 100 15.0 6.20 626 9.7 0.732 7.5 1.39 7.60 10.00

B217 216+46 to 219+58 RT 0.25 0.91 0.94 100 10.0 7.10 531 12.8 0.732 8.6 1.03 8.13 10.00

B220 219+58 to 220+82 RT 0.25 0.91 0.41 100 10.0 7.10 333 16.8 0.732 9.8 0.56 7.67 10.00

B221 221+37 to 231+81 RT 0.32 0.91 8.42 100 9.0 6.71 1731 4.7 0.732 5.2 5.52 12.23 12.23

B222 223+17 to 233+12 LT 0.29 0.91 2.77 11 9.1 2.33 984 0.7 0.732 2.0 8.10 10.43 10.43

B233 231+81 to 233+12 RT 0.40 0.91 0.43 100 12.0 5.49 206 18.9 0.732 10.4 0.33 5.82 10.00

B234 233+36 to 241+85 RT 0.29 0.91 9.37 100 7.0 7.67 1719 7.0 0.732 6.3 4.52 12.18 12.18

Vistor Center Road

B290 290+00 - 295+00 RT 0.25 0.91 2.75 500 6.000 18.82 122 6.600 0.732 6.2 0.33 19.15 19.15

Tc

(min)

Visitor Center

Description K or C10Basin ID Area

(ac)

Length

(ft)

Slope ti

(min)

Length

(ft)

So k

See

Table

Velocity

(fps)

Travel

Time tt

(min)

Campground

Percent

Impervious

FINAL Tc

(min)

Rational Analysis

Standard Form SF-2 . Storm Drainage System Design (Rational Method Procedure) Corridor / Design Package: NV FLAP US93(1) Pahranagat NWR Access Computed: AJF Date: 8/16/2018

System Name: Visitor Center Entrance, Campground Entrance Checked: EVS Date: 9/24/2019

Design Storm: 10-yr

A R

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IG

N

(n a m e

A R

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A

C

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F t c

(M

IN

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(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

109+48 to 116+42 RT B110 2.45 0.35 10.00 0.87 2.56 2.22 new cut ditch to offsite

122+83 to 124+64 RT B125 0.79 0.48 10.00 0.38 2.56 0.98 trail parking area, fill ditch to Culvert 124+77

124+64 to 131+41 RT B131 1.53 0.47 10.14 0.72 2.55 1.83 swale between trail to Culvert 131+20

131+46 to 134+80 RT B132 0.42 0.51 10.00 0.22 2.56 0.55 fill ditch to Culvert 131+20

135+16 to 146+ RT B135 7.54 0.29 10.00 2.21 2.56 5.67 fill ditch

204+82 TO 207+45 RT B205 0.79 0.25 10.00 0.20 2.56 0.51 fill ditch to offsite

207+45 to 209+37 RT B209 1.58 0.25 10.21 0.40 2.54 1.00 fill ditch to Culvert 209+47

209+52 to 215+27 RT B210 2.88 0.25 10.00 0.72 2.56 1.84 fill ditch to Culvert 209+47

215+27 to 216+26 RT B216 0.12 0.25 10.00 0.03 2.56 0.08 fill ditch to Culvert 216+36

216+46 to 219+58 RT B217 0.94 0.25 10.00 0.24 2.56 0.60 10.00 0.34 2.56 0.86 fill ditch to Culvert 216+36

219+58 to 220+82 RT B220 0.41 0.25 10.00 0.10 2.56 0.26 cut ditch to B217

221+37 to 231+81 RT B221 8.42 0.32 12.23 2.74 2.36 6.46 cut ditch to Inlet 222+66 Rt.

223+17 to 233+12 LT B222 2.77 0.29 10.43 0.79 2.52 1.99 cut ditch to campground entrance

231+81 to 233+12 RT B233 0.43 0.40 10.00 0.17 2.56 0.44 Fill ditch to Culvert 233+18

233+36 to 241+85 RT B234 9.37 0.29 12.18 2.67 2.37 6.32 Cut and fill ditch to Culvert 233+18

(1) Basin Description linked to C-Value Sheet (7) =Column 4 x Column 5

(2) Basin Design Point (8) from IDF Tab

(3) Enter the Basin Name from C Value Sheet (9) =Column 7 x Column 8

(4) Basin Area linked to C-Value Sheet (10) max Tc of combined basins

(5) Composite C linked to C-Value Sheet (11) Add the Basin Areas (7) to get the combined basin AC

(6) Time of Concentration linked to T of C Sheet (12) from IDF Tab

(13) Column 11 x Column 12

Visitor Center

Campground

REMARKSLOCATION

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IN

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DIRECT RUNOFF TOTAL RUNOFF

Rational Analysis

Corridor / Design Package: NV FLAP US93(1) Pahranagat NWR Access Computed: AJF Date: 8/16/2018

System Name: Visitor Center Entrance, Campground Entrance Checked: EVS Date: 9/24/2019

Design Storm: 25-yr

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(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

109+48 to 116+42 RT B110 2.45 0.38 10.00 0.92 3.40 3.13 new cut ditch to offsite

122+83 to 124+64 RT B125 0.79 0.51 10.00 0.40 3.40 1.37 trail parking area, fill ditch to Culvert 124+77

124+64 to 131+41 RT B131 1.53 0.49 10.14 0.75 3.38 2.54 swale between trail to Culvert 131+20

131+46 to 134+80 RT B132 0.42 0.53 10.00 0.22 3.40 0.76 fill ditch to Culvert 131+20

135+16 to 146+ RT B135 7.54 0.32 10.00 2.40 3.40 8.15 fill ditch

204+82 TO 207+45 RT B205 0.79 0.28 10.00 0.22 3.40 0.74 fill ditch to offsite

207+45 to 209+37 RT B209 1.58 0.28 10.21 0.43 3.38 1.47 fill ditch to Culvert 209+47

209+52 to 215+27 RT B210 2.88 0.28 10.00 0.79 3.40 2.69 fill ditch to Culvert 209+47

215+27 to 216+26 RT B216 0.12 0.28 10.00 0.03 3.40 0.11 fill ditch to Culvert 216+36

216+46 to 219+58 RT B217 0.94 0.28 10.00 0.26 3.40 0.88 10.00 0.37 3.40 1.26 fill ditch to Culvert 216+36

219+58 to 220+82 RT B220 0.41 0.28 10.00 0.11 3.40 0.38 cut ditch to B217

221+37 to 231+81 RT B221 8.42 0.35 12.23 2.93 3.13 9.19 cut ditch to Inlet 222+66 Rt.

223+17 to 233+12 LT B222 2.77 0.31 10.43 0.86 3.35 2.87 cut ditch to campground entrance

231+81 to 233+12 RT B233 0.43 0.42 10.00 0.18 3.40 0.62 Fill ditch to Culvert 233+18

233+36 to 241+85 RT B234 9.37 0.31 12.18 2.90 3.14 9.11 Cut and fill ditch to Culvert 233+18

(1) Basin Description linked to C-Value Sheet (7) =Column 4 x Column 5

(2) Basin Design Point (8) from IDF Tab

(3) Enter the Basin Name from C Value Sheet (9) =Column 7 x Column 8

(4) Basin Area linked to C-Value Sheet (10) max Tc of combined basins

(5) Composite C linked to C-Value Sheet (11) Add the Basin Areas (7) to get the combined basin AC

(6) Time of Concentration linked to T of C Sheet (12) from IDF Tab

(13) Column 11 x Column 12

Campground

Visitor Center

REMARKSLOCATION

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Corridor / Design Package: NV FLAP US93(1) Pahranagat NWR Access Computed: AJF Date: 9/4/2018

System Name: Visitor Center Entrance, Campground Entrance Checked: EVS Date: 9/24/2019

Design Storm: 100-yr

A R

S m e

A R

E A

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(I N

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(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

109+48 to 116+42 RT B110 2.45 0.57 10.00 1.39 5.02 6.99 new cut ditch to offsite

122+83 to 124+64 RT B125 0.79 0.60 10.00 0.48 5.02 2.39 trail parking area, fill ditch to Culvert 124+77

124+64 to 131+41 RT B131 1.53 0.64 10.14 0.98 5.00 4.90 swale between trail to Culvert 131+20

131+46 to 134+80 RT B132 0.42 0.67 10.00 0.28 5.02 1.42 fill ditch to Culvert 131+20

135+16 to 146+ RT B135 7.54 0.53 10.00 3.98 5.02 19.96 fill ditch

204+82 TO 207+45 RT B205 0.79 0.50 10.00 0.40 5.02 1.98 fill ditch to offsite

207+45 to 209+37 RT B209 1.58 0.50 10.21 0.79 4.98 3.94 fill ditch to Culvert 209+47

209+52 to 215+27 RT B210 2.88 0.50 10.00 1.44 5.02 7.23 fill ditch to Culvert 209+47

215+27 to 216+26 RT B216 0.12 0.50 10.00 0.06 5.02 0.30 fill ditch to Culvert 216+36

216+46 to 219+58 RT B217 0.94 0.50 10.00 0.47 5.02 2.36 10.00 0.68 5.02 3.39 fill ditch to Culvert 216+36

219+58 to 220+82 RT B220 0.41 0.50 10.00 0.21 5.02 1.03 cut ditch to B217

221+37 to 231+81 RT B221 8.42 0.55 12.23 4.63 4.63 21.43 cut ditch to Inlet 222+66 Rt.

223+17 to 233+12 LT B222 2.77 0.52 10.43 1.45 4.95 7.17 cut ditch to campground entrance

231+81 to 233+12 RT B233 0.43 0.60 10.00 0.26 5.02 1.30 Fill ditch to Culvert 233+18

233+36 to 241+85 RT B234 9.37 0.52 12.18 4.90 4.64 22.75 Cut and fill ditch to Culvert 233+18

(1) Basin Description linked to C-Value Sheet (7) =Column 4 x Column 5

(2) Basin Design Point (8) from IDF Tab

(3) Enter the Basin Name from C Value Sheet (9) =Column 7 x Column 8

(4) Basin Area linked to C-Value Sheet (10) max Tc of combined basins

(5) Composite C linked to C-Value Sheet (11) Add the Basin Areas (7) to get the combined basin AC

(6) Time of Concentration linked to T of C Sheet (12) from IDF Tab

(13) Column 11 x Column 12

Visitor Center

Campground

REMARKSLOCATION

D E

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IN

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Alamo, NV IDF Computed: AJF Date: 8/9/2019

NOAA Atlas 14 Checked: EVS Date: 9/24/2019

Time (in/hr)

(min) 2 Yr 5 Yr 10 Yr 25 Yr 50 Yr 100 Yr

5 1.92 2.7 3.37 4.46 5.45 6.6

6 1.830 2.570 3.210 4.250 5.190 6.280

7 1.740 2.440 3.050 4.040 4.930 5.970

8 1.640 2.310 2.880 3.820 4.670 5.650

9 1.550 2.180 2.720 3.610 4.410 5.340

10 1.46 2.05 2.56 3.4 4.15 5.02

11 1.410 1.980 2.470 3.280 4.010 4.850

12 1.360 1.910 2.380 3.160 3.860 4.670

13 1.310 1.840 2.300 3.050 3.720 4.500

14 1.260 1.770 2.210 2.930 3.570 4.320

15 1.21 1.70 2.12 2.81 3.43 4.15

16 1.180 1.660 2.070 2.750 3.360 4.060

17 1.160 1.630 2.030 2.690 3.280 3.970

18 1.130 1.590 1.980 2.630 3.210 3.880

19 1.100 1.550 1.940 2.560 3.130 3.790

20 1.080 1.510 1.890 2.500 3.060 3.700

21 1.050 1.480 1.840 2.440 2.980 3.610

22 1.030 1.440 1.800 2.380 2.910 3.520

23 1.000 1.400 1.750 2.320 2.830 3.430

24 0.970 1.360 1.710 2.260 2.760 3.340

25 0.950 1.330 1.660 2.200 2.680 3.250

26 0.920 1.290 1.610 2.140 2.610 3.160

27 0.890 1.250 1.570 2.070 2.530 3.070

28 0.870 1.210 1.520 2.010 2.460 2.980

29 0.840 1.180 1.480 1.950 2.380 2.890

30 0.814 1.14 1.43 1.89 2.31 2.8

31 0.800 1.130 1.410 1.870 2.280 2.760

32 0.790 1.110 1.390 1.840 2.250 2.730

33 0.780 1.100 1.380 1.820 2.220 2.690

34 0.770 1.080 1.360 1.790 2.190 2.660

35 0.760 1.070 1.340 1.770 2.160 2.620

36 0.750 1.050 1.320 1.750 2.130 2.590

37 0.740 1.040 1.300 1.720 2.100 2.550

38 0.730 1.020 1.280 1.700 2.080 2.510

39 0.720 1.010 1.270 1.670 2.050 2.480

40 0.710 1.000 1.250 1.650 2.020 2.440

41 0.700 0.980 1.230 1.630 1.990 2.410

42 0.690 0.970 1.210 1.600 1.960 2.370

43 0.680 0.950 1.190 1.580 1.930 2.340

44 0.670 0.940 1.170 1.550 1.900 2.300

45 0.660 0.920 1.160 1.530 1.870 2.270

46 0.650 0.910 1.140 1.510 1.840 2.230

47 0.640 0.890 1.120 1.480 1.810 2.190

48 0.630 0.880 1.100 1.460 1.780 2.160

49 0.620 0.870 1.080 1.430 1.750 2.120

50 0.610 0.850 1.060 1.410 1.720 2.090

51 0.600 0.840 1.050 1.390 1.690 2.050

52 0.590 0.820 1.030 1.360 1.660 2.020

53 0.580 0.810 1.010 1.340 1.640 1.980

54 0.570 0.790 0.990 1.310 1.610 1.940

55 0.550 0.780 0.970 1.290 1.580 1.910

56 0.540 0.760 0.960 1.270 1.550 1.870

57 0.530 0.750 0.940 1.240 1.520 1.840

58 0.520 0.740 0.920 1.220 1.490 1.800

59 0.510 0.720 0.900 1.190 1.460 1.770

60 0.503 0.707 0.882 1.17 1.43 1.73 i

0 10 20 30 40 50 60

R a in fa ll I n te n si ty in /h r)

Time (min)

Alamo, NV Lincoln County

IDF Curve

2 Yr

5 Yr

10 Yr

25 Yr

50 Yr

100 Yr

Data gathered: 8/6/2019

Project Location

Appendix C Hydraulics

Pahranagat NWR Access NV FLAP 93(1)

Ditch Analysis

Label Solve For

Friction

Method

Roughness

Coefficient

Channel

Slope (ft/ft)

Normal

Depth (ft)

Left Side

Slope (ft/ft

(H:V))

Right Side

Slope (ft/ft

(H:V))

Discharge

(ft³/s)

Flow Area

(ft²)

Wetted

Perimeter

(ft)

Hydraulic

Radius (ft)

Top Width

(ft)

Critical

Depth

(ft)

Critical

Slope

(ft/ft)

Velocity

(ft/s)

Velocity

Head

(ft)

Specific

Energy (ft)

Froude

Number Flow Type

Triangular Channel - 109+55 to 110+30 Rt Normal Depth

Manning

Formula 0.03 0.0187 0.6 3 3 3.13 1.07 3.78 0.28 3.58 0.58 0.02121 2.92 0.13 0.73 0.94 Subcritical

Triangular Channel - 110+30 to 111+45 Rt Normal Depth

Manning

Formula 0.03 0.0129 0.64 3 3 3.13 1.23 4.05 0.3 3.84 0.58 0.02121 2.54 0.1 0.74 0.79 Subcritical

Triangular Channel - 111+45 to 115+95 Rt Normal Depth

Manning

Formula 0.03 0.0135 0.64 3 3 3.13 1.21 4.02 0.3 3.81 0.58 0.02121 2.59 0.1 0.74 0.81 Subcritical

Triangular Channel - 124+90 to 131+30 Rt Normal Depth

Manning

Formula 0.03 0.0029 0.78 3 3 2.54 1.84 4.96 0.37 4.7 0.54 0.02181 1.38 0.03 0.81 0.39 Subcritical

Triangular Channel - 131+75 to 134+45 Rt Normal Depth

Manning

Formula 0.03 0.0236 0.34 3 3 0.76 0.34 2.13 0.16 2.02 0.33 0.02562 2.24 0.08 0.41 0.96 Subcritical

Triangular Channel - 205+72 to 207+44 Rt Normal Depth

Manning

Formula 0.03 0.0168 0.35 3 3 0.74 0.38 2.25 0.17 2.13 0.33 0.02571 1.96 0.06 0.41 0.82 Subcritical

Triangular Channel - 207+44 to 209+37 Rt Normal Depth

Manning

Formula 0.03 0.0621 0.36 3 3 1.47 0.39 2.27 0.17 2.16 0.43 0.02346 3.79 0.22 0.58 1.58 Supercritical

Triangular Channel - 209+52 to 215+27 Rt Normal Depth

Manning

Formula 0.03 0.0323 0.51 3 3 2.69 0.78 3.22 0.24 3.06 0.55 0.02164 3.45 0.19 0.69 1.21 Supercritical

Triangular Channel - 216+47 to 219+58 Rt Normal Depth

Manning

Formula 0.03 0.04022 0.32 3 3 0.88 0.31 2.03 0.15 1.93 0.35 0.02512 2.84 0.12 0.45 1.25 Supercritical

Triangular Channel - 219+58 to 220+72 Rt Normal Depth

Manning

Formula 0.03 0.008 0.32 3 3 0.38 0.3 2.01 0.15 1.91 0.25 0.0281 1.25 0.02 0.34 0.55 Subcritical

Triangular Channel - 222+65 to 231+47 Rt Normal Depth

Manning

Formula 0.03 0.0077 1.06 3 3 9.19 3.35 6.68 0.5 6.34 0.9 0.01837 2.74 0.12 1.17 0.67 Subcritical

Triangular Channel - 233+37 to 234+67 Rt Normal Depth

Manning

Formula 0.03 0.0078 1.05 3 3 9.11 3.31 6.65 0.5 6.3 0.89 0.0184 2.75 0.12 1.17 0.67 Subcritical

Triangular Channel - 234+67 to 236+12 Rt Normal Depth

Manning

Formula 0.03 0.001 1.54 3 3 9.11 7.16 9.77 0.73 9.27 0.89 0.01839 1.27 0.03 1.57 0.26 Subcritical

Triangular Channel - 223+12 to 227+47 Lt Normal Depth

Manning

Formula 0.03 0.0126 0.62 3 3 2.87 1.16 3.94 0.3 3.74 0.56 0.02146 2.47 0.09 0.72 0.78 Subcritical

FlowMaster Channel Hydraulics Summary