Final Hydraulics Report - CA MOJA 12(1) flat.pdf

Cima Road San Bernardino, CA

CA NPS MOJA 12(1)

Final Hydraulics Report

Federal Highway Administration Central Federal Lands Highway Division

September 8, 2022

Signature Sheet

Report prepared by: ____________________________________________________

James Neighorn, P.E., Hydraulic Engineer

Report reviewed by: ____________________________________________________

Aaron Estep, P.E., Hydraulics Engineer

Approved for distribution by: ____________________________________________________

Luis Calderon, P.E., Lead Hydraulics Engineer

Distribution

Electronic:

Neil Ogden, Project Manager Thomas McCrary, Lead Designer Thomas Parker, Environmental Protection Specialist Devin Dixon, Geotechnical Engineer

AARON PAUL

ESTEP

Digitally signed by AARON PAUL

ESTEP

Date: 2022.09.15 08:50:23 -06'00'

LUIS GERARDO CALDERON

ARCE

Digitally signed by LUIS GERARDO

CALDERON ARCE

Date: 2022.09.15 13:14:03 -06'00'

Executive Summary Hydrologic and hydraulic analyses were conducted for the CA NPS MOJA 12(1) Cima Road project located in Mojave National Preserve, San Bernardino County, California. The National Park Service (NPS) is rehabilitating 17.6 miles of Cima Road (Route 12). The road improvements include increasing the roadway width to a consistent 26 feet for the design speed, providing low water crossings, improving safety with longitudinal and transverse rumble strips, signing, pavement markings, paved pullouts; and possible mitigation for the endangered federally listed Desert Tortoise. Three additional roadway sites, where flood damage has occurred within the Park, have been added to the project. The first site is located on Lanfair Road (Route 14) just south of Hackberry Mountain. A 4,000 foot length of roadway will need to be improved with low water crossings to prevent flood waters from causing damage. The second site is located along Cedar Canyon Road (Route 16) just east of the Rock Springs Loop Trailhead. Improvements along a 1,500 foot length of roadway that crosses a floodway will need to be reconstructed to prevent roadway damage during flood events. The third additional site is located along Kelbaker Road just North of the Kelso Depot Visitor Center. Improvements consist of repair at for short segments of pavement where flood waters have eroded the edge of the roadway. The following report summarizes hydraulic design criteria, computational methods, and final hydraulics recommendations for general drainage, low water crossings, and culvert improvements.

CA NPS MOJA 12(1) – Final Hydraulics Report

Table of Contents 1 Project Background Information

2 Hydraulic Design Criteria

3 Hydrology

3.1 Hydrologic Setting

3.2 Peak Discharge Estimates

3.3 Recommended Design Discharges

4 Hydraulic Recommendations

4.1 Existing Conditions

4.1.1 Cima Road

4.1.2 Lanfair Road

4.1.3 Cedar Canyon Road

4.1.4 Kelbaker Road

4.2 Recommendations

4.2.1 Cima Road

4.2.2 Lanfair Road

4.2.3 Cedar Canyon Road

4.2.4 Kelbaker Road

5 Appendices

6 References

Tables

Table 1: Cima Road Proposed Leadoff Ditch Locations Table 2: Cima Road Re establishment/Construct Roadside Berms Table 3: Locations to Review Grade Raise or Increased Ditch Capacity Options Table 4: Cima Road Proposed Low Water Crossing (LWC) Table 5: Lanfair Road Proposed Low Water Crossing (LWC) Table 6: Kelbaker Road – Full Depth Patch Table 7: Appendix Summary

Figures

Figure 1: Project Location Map

Appendices

Appendix A: Drainage Basin Delineations and Estimated Peak Flows Appendix B: Dome Fire Emergency Stabilization Plan Appendix C: Design Peak Discharge Summary Appendix D: Figures Appendix E: Photos

1 PROJECT BACKGROUND INFORMATION

The Central Federal Lands Highway Division (CFLHD) in cooperation with the National Park Service (NPS) plan to rehabilitating 17.6 miles of Cima Road (Route 12) and make improvements to floodway damaged sites on Lanfair Road (Route 14), Cedar Canyon Road (Route 16), and Kelbaker Road within the Mojave National Preserve, California.

The Cima Road project begins at the northern boundary of the preserve at the I 15 highway and extends

17.6 miles southeast between the Cima Dome and Kessler Peak. The project ends at the intersection with Morning Star Mine Road. The existing roadway width varies from 20 to 24 feet and is characterized by extremely soft shoulders, numerous low water crossings and deteriorating pavement conditions. The improvements to Cima Road includes increasing the roadway width to a consistent 26 feet for the design speed, providing low water crossings, improving safety with longitudinal and transverse rumble strips, signing, pavement markings, paved pullouts; and possible mitigation for the endangered federally listed Desert Tortoise.

Additional improvements to Lanfair, Cedar Canyon, and Kelbaker Road are also included as part of the proposed project. Low Water Crossings (LWC) at two separate locations along Lanfair Road are needed to prevent flood waters from causing damage. The low water crossings are located at Vontrigger Hills and will include buried concrete barriers and riprap protection. Along Cedar Canyon Road, just east of Rock Springs Loop Trailhead, improvements along a 1,500 foot length of roadway are needed to provide amore maintainable roadway across the Watson Wash floodway. Full depth pavement repair patches are needed at several locations along Kelbaker Road where the pavement has been undermined by erosion.

Figure 1: Project Location Map

2 HYDRAULIC DESIGN CRITERIA

The Federal Lands Highway Project Development and Design Manual (PDDM) establishes the hydraulic design criteria for this project (Federal Lands Highway 2012).

Cima Road is paved with a design speed of 55 mph, a design average daily traffic (ADT) of 1,718 vehicles and is designated as a principal park access road. Based on these parameters, the corridor is classified as a high standard roadway for hydraulic design purposes. Roadway culverts and low water crossings will be designed based on the 50 year flood.

Lanfair and Cedar Canyon Roads are unpaved dirt roads with an average daily traffic (ADT) of less than 70 vehicles. Based on these parameters, the corridors are classified as low standard roadways for hydraulic design purposes. Roadway culverts and low water crossings will be designed based on the 25 year flood.

3 HYDROLOGY

3.1 HYDROLOGIC SETTING

TheMojave National Preserve is located at the confluence of theMojave, Sonoran, and Great Basin Desert regions. The preserve is in a geologically diverse desert region. The mesas, dunes, mountains, arroyos, small mountain slope seeps and springs within the preserve range in elevation from 7,900 feet to 900 feet in elevation. The preserve experiences extreme heat during the summers with rainfall varying from 4 to 12 inches per year. Most of the precipitation occurs between November and March with short intense thunderstorms typically occurring during the Summer. During the less intense rainfall events the porous alluvium soils allows water to infiltrate preventing any significant surface runoff. Surface water flow within typically dry arroyos and washes is limited to occasional flash flood flows resulting from rapid snowmelt or large thunderstorms. The many ephemeral stream channels, that transport runoff and sediment from the adjacent peaks and dome during these larger storm events, have formed complex alluvial fans that spread across the flat desert floor.

The contributing drainage basins for each crossing selected for evaluation were delineated using the StreamStats web application (version 4.4.0). Drainage basin delineations and areas have been included in Appendix A.

3.2 PEAK DISCHARGE ESTIMATES

The drainages within the preserve are unregulated and ungaged. Therefore, peak discharges for the crossings analyzed were estimated using the StreamStats web application (version 4.4.0). StreamStats utilizes regional regression equations for estimation of natural streamflow statistics in California (U.S.G.S Report Number 2012 5113). The equations developed for this region relate peak discharge directly to drainage area.

The Cima Dome fire recently burned a large area along the south portion of Cima Road. Several basins draining to Cima Road are within the burn zone. The Dome Fire Emergency Stabilization Plan, dated September 2020, provides estimated increased flows expected within these basins during the vegetation and soil recovery period for the 10 year and 25 year events. The stabilization plan prepared by the Burn

Area Emergency Response team used the AGWA/KINEROS2 modeling framework to assess the post fire storm runoff and erosion. The post fire recovery flows have been evaluated against the flows predicted using StreamStats and the larger of the flows has been used in analysis.

Peak runoff estimates computed from StreamStats are attached to this report in Appendix A. The Dome Fire Emergency Stabilization Plan are attached to this report in Appendix B.

3.3 RECOMMENDED DESIGN DISCHARGES

Cima Road has been designated as a high standard roadway for hydraulic design purposes. For this roadway designation, the design storm used for the proposed culvert crossings is the 50 year event. An event of this magnitude has a 2% Annual Exceedance Probability (AEP). For basins impacted by the Dome Fire, the peak flows produced by the 50 year event may be exceeded by shorter return period 25 year post fire recovery flows. Therefore, flows will need to be evaluated and the event producing the greater discharge shall be used for any fire impacted basins.

Cedar Canyon Road has been designated as a low standard roadway for hydraulic design purposes. For this roadway designation, the design storm used for embankment or roadway scour countermeasures within the floodway channel is the 25 year event. An event of this magnitude has a 4% Annual Exceedance Probability (AEP).

Design of the low water crossings along Cima, Lanfair, and Cedar Canyon Roads will follow guidance in the PDDM. Crossings will be sized to provide flow capacity for a 10 year event and be stable during a 25 year event. A 10 year event of has a 10% Annual Exceedance Probability (AEP). Estimates of flow within the Dome fire burn area will need to account for the increases resulting from fire. The design of the crossings will consider two parameters:

1. The visual length of the wash from aerial photographs or field observations and,

2. The depth of overtopping during the 10 year flood event.

Recommended design discharges have been compiled in Appendix C.

4 HYDRAULIC RECOMMENDATIONS

4.1 EXISTING CONDITIONS

4.1.1 Cima Road

Cima road extends across the valley floor and alluvial fans where it intersects and intercepts several the ephemeral channels. In many areas, intercepted runoff is forced to flow along the roadside ditches. In some locations, the intercepted flood runoff exceeds the roadside ditches transport capacity resulting in erosion of the roadway shoulder, pavement, or deposition of sediment within the ditches and water flowing onto the roadway. In these locations, ditch capacity will need to be increased or the roadway grade will need to be raised (were feasible) to prevent continued damage and flow along the roadway surface.

Leadoff ditches have been constructed throughout the roadway corridor. These ditches direct flows away from the roadway dispersing them onto the desert floor or natural channels. These leadoff ditches are often blocked or plugged during ditchmaintenance operations or flood events. All existing leadoff ditches will need to be inspected and cleared of deposited sediment and debris. There are also locations where additional leadoff ditches should also be constructed to provide relief to the roadway ditch system.

Along a majority of the roadway, excess material side cast during roadside ditch cleaning has formed berms adjacent to the ditches. These berms can be beneficial in keep off road runoff from entering the roadside ditches. At several locations, these berms have been overtopped and eroded by off road runoff which has inundate the roadside ditches and damaged the roadway. Re establishing these berms, and in some places additional berm construction, will be needed to prevent future damage to the roadway.

There are many locations where larger ephemeral channels intersect perpendicular to the road sending flood waters and debris over the top of the road. Dips in the roadway have been constructed to help concentration of flow at some of these locations. At many of these crossings the amount of flow and/or velocities were not high enough to cause observable damage to the roadway. However, erosion and loss of pavement along the downstream side of the road was observed at five (5) of the channel crossing locations. Low water crossing systems will need to be constructed in these locations to prevent future damage to the roadway.

There are two culverts located within the project corridor. The first culvert is located immediately south of the gas station at the beginning of the project (highway I 15 interchange) at Station 103+25. The second culvert is located adjacent to the Kessler Springs Ranch at Station 777+05.

The culvert at Station 103+25 consists of a 24 inch corrugated metal pipe culvert. Flood flows have overtopped the road at this location resulting in significant erosion at the culvert outlet and undercutting of the roadway pavement. Asphalt curbs are located on both sides of the roadway over the culvert. The curbs extend south of the culvert approximately 400 feet. The curbs collect any overflow from a lowwater crossing to the south and directs it along the roadway shoulder to a low point and curb opening immediately south of the culvert. Flood flows have overtopped the curb causing undercutting of rock filled gabion baskets and roadway pavement around the low point.

The culvert at Station 777+05 consists of a 5’x7’ concrete box culvert. The original box culvert included beveled end sections which have since been modified. The modification extended the top of the culvert to allow room for extra paved/shoulder width and guardrail. Cast in place concrete was extended partially over the beveled ends to form a longer full box shape. The culvert capacity appears to be adequate since no signs of roadway overtopping were observed. However, flood flows have eroded the road embankment around both ends of the culvert. This leaves the culvert extensions exposed and guardrail elevated at an unsafe height.

4.1.2 Lanfair Road

Bedrock outcroppings, near Vontrigger Hills, forces flood waters to concentrate and cross Lanfair Road at two locations. The roadway experiences significant erosion during storm events at these locations.

The first northerly crossing consists of a gravel roadway surface. This crossing requires regular heavy maintenance to re open after large storm events.

A paved low water crossing has been constructed along the second southerly crossing. Downstream of the crossing the channel appears to be degrading. The existing paved segment prevents the channel degradation from progressing and eroding deep cuts across the roadway. However, pavement loss on downstream side of the crossing and along segments of the travelway has occurred. Heavy maintenance keeps the road open after large storm events, but the missing sections of pavement creates a rough driving surface which is difficult to evenly graded.

A new low water crossing systems will need to be constructed at the first northerly location to prevent future damage to the roadway. The existing low water crossing at the second southerly location will need to be replaced with a more stable system which can be more easily maintained.

4.1.3 Cedar Canyon Road

Cedar Canyon Road crosses theWatsonWash floodway, just east of Rock Springs Loop Trailhead and New York Mountain Road. Outside of the floodway, Cedar Canyon Road is elevated well above the floodway.

As the roadway approaches the floodway from the west it gradually drops down and parallels the floodway, running southeast for approximately 500 feet. At this point the road grade matches the floodway bottom. The roadway then runs across a mainstem of the floodway and curves slightly east running down the middle of a second mainstem channel for approximately 800 feet. From there the roadway rises out of the floodway onto a stable upland bench to the east.

In the past, flooding has washed away the embankment along the 500 foot elevated segment that parallels the floodway on the west. The Preserve performed major construction re building the embankment and road grade. Further flood events have continued to erode the toe of the new embankment. Portions of the embankment, where the road grade nears the floodway bottom, have also washed out. This leaves vertical drop offs in the roadway at both sides of the floodway which require reconstruction. For the segment of roadway that runs down the middle of the second mainstem channel, eroded surfacing has been repaired using heavy maintenance.

Without measures to re align/re grade the roadway and protect elevated embankments from erosion within the floodway limits, the need for heavy maintenance and roadway reconstruction will continue.

Signs of minor channel degradation (2 to 3 feet) were observed within the floodway. Any erosion countermeasures will need to account for possible channel degradation along with possible local scour.

4.1.4 Kelbaker Road

An approximate 2.6 mile segment of Kelbaker Road immediately north of Kelso has four short segments where the pavement edge has been undermined by past flood events and will need to be reconstructed.

The northern most segment is located near a rock outcrop which concentrates floodway flows up against and parallel to the roadways west shoulder. Removal or blasting of the rock outcropping to provide a wider unconfined flow area will not be allowed at this location. Therefore, additional protectivemeasures will be needed at this location to prevent significant future erosion.

4.2 RECOMMENDATIONS

4.2.1 Cima Road

General Drainage Recommendations

The following recommendations will help improve drainage capacity and prevent erosion along Cima Road:

Reconstruct the roadside curbs from 105+14 to 107+10 right and 103+62 to 107+35 left to direct runoff to a low point and curb opening located at approximately 104+90 right.

Clean all roadside ditches to improve or restore flow capacity and prevent overtopping onto the roadway.

Clean or re establish existing leadoff ditches along the project corridor. Construct additional leadoff ditches identified in Table 1 to disperse flows from roadside ditches onto the desert floor.

Table 1: Cima Road Proposed Leadoff Ditch Locations

Station Left/Right Length (ft.) Flow Direction

181+02 Rt 25 NW

211+22 Rt 125 NW

265+02 Lt 75 NE

643+12 Rt 100 NW

644+82 Lt 75 NE

Notes:

1. Verify proposed work does not extend into the designated wilderness area.

Re establish or construct roadside berms to prevent offsite runoff from entering the roadside ditch at locations listed in Table 2.

Table 2: Cima Road Re establishment/Construct Roadside Berms

Station Left/Right Length (ft.)

137+62 to 139+02 Rt 140

265+12 to 265+42 Lt 30

317+02 to 318+62 Lt 160

1. Station limits of berms are approximate and will need to be adjusted to tie into existing berms or drainage discharge points.

Review options for providing a wider ditch or raising the road grade in locations where flows currently overtop the roadway during large storm events at locations listed in Table 3.

Table 3: Locations to Review Grade Raise or Increased Ditch Capacity Options

Station Range

204+00 to 209+00

219+50 to 230+00

293+50 to 299+50

317+00 to 344+00 Notes:

1. Station ranges are approximate, and improvements should be made to increase drainage capacity were feasible and practical while limiting construction impacts in sensitive areas.

Culvert Crossings

Figures identifying the location of culverts and adjacent features are included in Appendix D.

Culvert 1 (Station 103+25): This culvert will need to be replaced with a larger structure. There is limited ability to raise the road grade due to the adjacent property and driveway accesses. The replacement structure will be designed to fit within the existing grade profile once the roadway survey is completed.

The culvert will include headwalls on both ends to improve capacity and prevent erosion. Additional riprap protection will be needed at the outlet to prevent continued erosion.

The curbs and low point south of the culvert will need to be reconstructed to continue accommodating overtopping flows intercepted by the roadway and overflow from the low water crossing to the south.

Install a low water crossing system along the downstream edge of the roadway from 102+70 to 105+00 to protect the pavement from becoming undermined by overtopping flows.

Culvert 2 (Station 777+08): The 5’x7’ concrete box culvert is within the burn area of the Cima Dome Fire.

Until vegetation can re establish, increases in flows and debris at this crossing can be expected during any large storms experienced in future.

The culvert currently provides adequate flow capacity and can be expected to accommodate increased flows/debris resulting from the burn area conditions but will need to be replaced to address the eroded roadway embankments and unsafe guardrail installation on both ends.

To address the embankment erosion and guardrail safety condition, headwalls and wingwalls will need to be added to the existing culvert or a replacement box culvert will need to be installed. Wingwalls will help to improve capacity and help pass the additional flow and debris resulting from the recent wildland fire.

To provide further emergency flow capacity at this crossing location the existing cattle guard immediately north of the culvert should be cleaned of debris.

Low Water Crossing Design and Recommendations

Design of the low water crossings followed guidance in the Project Development and Design Manual (PDDM) (FHWA 2008) that recommends sizing the capacity of a vented low water crossing for a 10 year event and having the crossing stabilized for a 25 year event. This project will install unvented low water crossings for which there are no design standards since all the water must pass over the roadway. The 10 year event was used to estimate the depth of flow over the roadway at the crossings. The design considered two parameters: 1.) the width of the wash measured from survey data, 2.) the depth of overtopping during the 10 year flood event.

To determine the depth of overtopping, a broad crested weir equation is assumed, which implies that the water approaches critical depth as it passes over the roadway. Eq. (1) is a common equation for broad crested weirs and Eq. (2) rearranges Eq. (1) to be solved for depth.2.62 / (1)

Where, L = length of weir crest andH = the total head of water approaching the weir, and 2.62 is a constant that includes gravity and the discharge coefficient which accounts for hydraulic losses. The length of the weir crest is taken as the width of the washmeasured perpendicular to the flow. If the total head of water approaching the control section is assumed to be the depth of overtopping1 on the roadway segment, then Eq. (2) is used to solve for the depth of overtopping on the roadway.

. , (2)

1 As water passes over a control section potential energy is being transferred into kinetic energy and the total head becomes the sum of the velocity head and hydraulic depth, therefore the actual hydraulic depth is less than the total head by the value of the velocity head or / 2 , where d is the overtopping depth and v is the velocity over the roadway segment. For a control section with a high length to depth ratio, as the low water crossings have, the velocity head is considered to be small compared to the overtopping depth and .

Where, d is the overtopping depth in feet on the roadway section. Eqs. (1) and (2) are general assumptions for overtopping depth and controlled by the existing roadway section, which may or may not be adjusted for this project but are still analyzed in the case that the park is willing to provide minor grade changes at the locations.

The wash width at each crossing are listed in Table 4. At these lengths, the depth of overtopping found from Eq. (2) are also listed in Table 4.

The hydraulic design of the low water crossings is meant to stabilize the road for the 10 year event. Low water crossing signs should be installed on both sides of the crossing.

Low water crossings shall consist of buried jersey barriers placed along the downstream paved edge of the crossing. In areas where flows may travel parallel to the upstream edge of the roadway, buried jersey barriers will also be placed on the upstream paved edge of the crossing. The top of the barriers will be set flush with the roadway edge. Riprap shall be placed downstream or upstream of the barriers to provide energy dissipation and limit erosion.

Table 4: Cima Road Proposed LowWater Crossing (LWC)

Low Water Crossing Locations

Station To Station Wash Width/ Weir Length L

(ft)

10-year Flood

Q (cfs)

Flow Depth d (ft)

Flow Direction

Cima Road

103+00 - 105+20 220/220 67 0.24 NW

108+05 - 110+85 160/280 1170 1.98 NW

602+20 - 606+60 110/440 320 1.07 NW

745+00 - 751+00 175/600 151 0.48 SE

889+30 - 891+10 80/180 185 0.92 E Notes:

See Appendix D for specific crossing details and dimensions Wash widths varies from weir lengths based on flow skew angle at crossing

4.2.2 Lanfair Road

The low water crossing on Lanfair Road shall consist of buried jersey barriers as described in the previous section. The wash width and estimated overtopping flow depth at the crossing are listed in Table 5.

Table 5: Lanfair Road Proposed Low Water Crossing (LWC)

Low Water Crossing Locations

Station To Station Wash

Width/Weir Length L (ft)

10-year Flood

Q (cfs)

Flow Depth d (ft)

Flow Direction

Lanfair Road

4000+00 - 4005+60 300/560 1040 1.21 SW

Notes: See Appendix D for specific crossing details and dimensions

4.2.3 Cedar Canyon Road

Installing erosion countermeasures to protect the 500 feet of elevated roadway embankment paralleling the west side of the floodway would require significant quantities of large rock which would be difficult to obtain. Where practicable, it is usually preferable to design the roadway so that countermeasures are minimized or not necessary.

Per field observations and discussions with the highway design engineer, it appears the roadway grade drop from the west can be transitioned more quickly to reduce the amount of elevated embankment material within the floodway. Increasing the grade drop starting from the intersection of New York Mountain Road will allow the roadway elevation to sooner match the channel bottom, within 50 feet of the floodway limits. This short segment of embankment material will need to be protected by placing an armored bank along its toe. The armoring will begin approximately at station 1204+40 and need to extend approximately 230 feet to station 1206+70. This will prevent additional channel migration to the west toward the roadway.

The remaining roadway running at channel gradewithin the floodway will continue to be exposed to flows and debris during flood events. The Preserve will need to continue addressing this using heavy maintenance equipment. However, the need for roadway embankment reconstruction will be eliminated or significantly reduced.

Paving or armoring of this segment of roadway as a long low water crossing was considered. This would be costly and still require significant maintenance under conditions at this site. Leaving this segment of roadway as gravel surface allows the road to adjust vertically with the floodway over time and avoids complicating maintenance with additional repairs that would be needed on pavement and armoring systems. Therefore, additional armoring of the at grade segment of roadway is not recommended.

At the east side of the floodway, the roadway grade should be lowered to match the floodway channel elevation. The upward grade transition should not begin until approximately 50 feet beyond the floodway bank. This will prevent the need for reconstructing an elevated embankment. The floodway bank should be armored for approximately 100 feet south of the roadway to prevent further migration of the floodway.

Armoring and erosion countermeasures have been designed to withstand expected flood flows and account for possible channel degradation along with possible local scour.

Figures identifying proposed roadway improvements and erosion countermeasures are included in Appendix D.

4.2.4 Kelbaker Road

Pavement repair along Kelbaker Road shall consist of full depth pavement patches along segments listed in Table 6.

Table 6: Kelbaker Road – Full Depth Patch

Station Left/Right Width (ft.)

2029+90 to 2030+42 Lt 3 2056+08 to 2057+35 Lt 6 2058+46 to 2058+98 Lt 3 2135+47 to 2637+00 Lt 6

To address the increased erosion potential at station 2135+47 to 2637+00 and prevent added constriction of the floodway from roadway embankment fill, an in stream rockery wall will need to be constructed along the edge of the roadway. This will increase flow capacity of the floodway and reduce roadway overtopping potential while protecting the road embankment from erosion.

5 APPENDICES

Table 7 provides a summary of the appendices included in this report.

Table 7: Appendix Summary

Appendix Name Description A Drainage Basin Delineations and Estimated Peak Flows Description B Dome Fire Emergency Stabilization Plan Description C Design Peak Discharge Summary Description D Figures Description

6 REFERENCES

CFLHD, Central Federal Lands Highway Division. 2015. "Placed Riprap at Culverts (C 251 50)." Detail Drawings: FP 14.

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

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

FEMA. n.d. "Definitions of FEMA Flood Zone Designations."

https://snmapmod.snco.us/fmm/document/fema flood zone definitions.pdf.

FHWA. 2018. Hydraulic Toolbox. Federal Highway Administation, Aquaveo.

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

NOAA. 2011. Precipitation Frequency Data Server. Silver Springs, MD. Accessed April 2019.

https://hdsc.nws.noaa.gov/hdsc/pfds/index.html.

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

U.S. Geological Survey. 2018. The National Map. https://viewer.nationalmap.gov/advanced viewer/.

USGS, U.S.Geological Survey. 2019. PeakFQ Flood Frequency Analysis. 7.3. Reston, VA, November 21.

Wolock, D.M. 2003. Flow characteristics at U.S. Geological Survey streamgages in the counterminous United States. Open File Report 03 146, digital data set, U.S. Geological Survey.

Appendix A – Drainage Basin Delineations and Estimated Peak Flows

StreamStats Report - Cedar Canyon Road Floodway Crossing Improvements

Peak-Flow Statistics Parameters[2012 5113 Region 6 Desert]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 10.8 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 34.3 ft^3/s 214

5 Year Peak Flood 200 ft^3/s 226

10 Year Peak Flood 503 ft^3/s 248

25 Year Peak Flood 1340 ft^3/s 298

50 Year Peak Flood 2530 ft^3/s 357

100 Year Peak Flood 4500 ft^3/s 444

200 Year Peak Flood 7570 ft^3/s 575

500 Year Peak Flood 14300 ft^3/s 856

Peak-Flow Statistics Citations

Gotvald, A.J., Barth, N.A., Veilleux, A.G., and Parrett, Charles,2012, Methods for determining magnitude and frequency of floods in California, based on data through water year 2006: U.S. Geological Survey Scientific Investigations Report 2012–5113, 38 p., 1 pl.

(http://pubs.usgs.gov/sir/2012/5113/)

Region ID: CA Workspace ID: CA20201125164739710000 Clicked Point (Latitude, Longitude): 35.15551, -115.32850 Time: 2020-11-25 08:47:57 -0800

Page 2 of 2StreamStats

11/25/2020https://streamstats.usgs.gov/ss/

StreamStats Report - Cima Road Sta 10 + 0 to 10 + 0

Basin Characteristics

Parameter Code Parameter Description Value Unit

DRNAREA Area that drains to a point on a stream 0.2 square miles

Peak-Flow Statistics Parameters[2012 5113 Region 6 Desert]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 0.2 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 4.56 ft^3/s 214

5 Year Peak Flood 26.6 ft^3/s 226

10 Year Peak Flood 66.9 ft^3/s 248

25 Year Peak Flood 178 ft^3/s 298

50 Year Peak Flood 337 ft^3/s 357

100 Year Peak Flood 598 ft^3/s 444

200 Year Peak Flood 1010 ft^3/s 575

500 Year Peak Flood 1900 ft^3/s 856

Peak-Flow Statistics Citations

Gotvald, A.J., Barth, N.A., Veilleux, A.G., and Parrett, Charles,2012, Methods for determining magnitude and frequency of floods in California, based on data through water year 2006: U.S. Geological Survey Scientific Investigations Report 2012–5113, 38 p., 1 pl.

(http://pubs.usgs.gov/sir/2012/5113/)

Region ID: CA Workspace ID: CA20201124234532177000 Clicked Point (Latitude, Longitude): 35.44072, -115.67356 Time: 2020-11-24 15:45:49 -0800

StreamStats Report - Cima Road Sta 1 + to 1 + 5

Basin Characteristics

Parameter Code Parameter Description Value Unit

DRNAREA Area that drains to a point on a stream 57.4 square miles

General Disclaimers

This watershed has been edited, computed flows may not apply.

Peak-Flow Statistics Parameters[2012 5113 Region 6 Desert]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 57.4 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 80 ft^3/s 214

5 Year Peak Flood 466 ft^3/s 226

10 Year Peak Flood 1170 ft^3/s 248

25 Year Peak Flood 3130 ft^3/s 298

50 Year Peak Flood 5900 ft^3/s 357

100 Year Peak Flood 10500 ft^3/s 444

200 Year Peak Flood 17600 ft^3/s 575

500 Year Peak Flood 33200 ft^3/s 856

Region ID: CA Workspace ID: CA20201124233522870000 Clicked Point (Latitude, Longitude): 35.43902, -115.67223 Time: 2020-11-24 15:35:39 -0800

StreamStats Report - Cima Road Sta 60 + 0 to 60 + 0

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 4.4 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 21.8 ft^3/s 214

5 Year Peak Flood 127 ft^3/s 226

10 Year Peak Flood 320 ft^3/s 248

25 Year Peak Flood 853 ft^3/s 298

50 Year Peak Flood 1610 ft^3/s 357

100 Year Peak Flood 2860 ft^3/s 444

200 Year Peak Flood 4800 ft^3/s 575

500 Year Peak Flood 9060 ft^3/s 856

Peak-Flow Statistics Citations

Gotvald, A.J., Barth, N.A., Veilleux, A.G., and Parrett, Charles,2012, Methods for determining magnitude and frequency of floods in California, based on data through water year 2006: U.S. Geological Survey Scientific Investigations Report 2012–5113, 38 p., 1 pl.

(http://pubs.usgs.gov/sir/2012/5113/)

Region ID: CA Workspace ID: CA20201125161319810000 Clicked Point (Latitude, Longitude): 35.33889, -115.56134 Time: 2020-11-25 08:13:38 -0800

Page 2 of 3StreamStats

StreamStats Report - Cima Road Sta 74 + 0 to 75 + 0

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 1 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 10.3 ft^3/s 214

5 Year Peak Flood 60 ft^3/s 226

10 Year Peak Flood 151 ft^3/s 248

25 Year Peak Flood 403 ft^3/s 298

50 Year Peak Flood 760 ft^3/s 357

100 Year Peak Flood 1350 ft^3/s 444

200 Year Peak Flood 2270 ft^3/s 575

500 Year Peak Flood 4280 ft^3/s 856

Peak-Flow Statistics Citations

Gotvald, A.J., Barth, N.A., Veilleux, A.G., and Parrett, Charles,2012, Methods for determining magnitude and frequency of floods in California, based on data through water year 2006: U.S. Geological Survey Scientific Investigations Report 2012–5113, 38 p., 1 pl.

(http://pubs.usgs.gov/sir/2012/5113/)

Region ID: CA Workspace ID: CA20201125161109323000 Clicked Point (Latitude, Longitude): 35.30479, -115.54096 Time: 2020-11-25 08:11:26 -0800

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 0.1 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 3.21 ft^3/s 214

5 Year Peak Flood 18.7 ft^3/s 226

10 Year Peak Flood 47.1 ft^3/s 248

25 Year Peak Flood 126 ft^3/s 298

50 Year Peak Flood 237 ft^3/s 357

100 Year Peak Flood 421 ft^3/s 444

200 Year Peak Flood 708 ft^3/s 575

500 Year Peak Flood 1330 ft^3/s 856

Peak-Flow Statistics Citations

Gotvald, A.J., Barth, N.A., Veilleux, A.G., and Parrett, Charles,2012, Methods for determining magnitude and frequency of floods in California, based on data through water year 2006: U.S. Geological Survey Scientific Investigations Report 2012–5113, 38 p., 1 pl.

(http://pubs.usgs.gov/sir/2012/5113/)

CA

CA20201125163432309000

35.29777, -115.53704

StreamStats Report - Cima Road Sta 77 +05 Region ID:

Workspace ID:

Clicked Point (Latitude, Longitude):

Time: 2020-11-25 08:34:51 -0800

StreamStats Report - Cima Road Sta 8 + 0 to 89 +

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 1.5 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 12.6 ft^3/s 214

5 Year Peak Flood 73.7 ft^3/s 226

10 Year Peak Flood 185 ft^3/s 248

25 Year Peak Flood 495 ft^3/s 298

50 Year Peak Flood 933 ft^3/s 357

100 Year Peak Flood 1660 ft^3/s 444

200 Year Peak Flood 2790 ft^3/s 575

500 Year Peak Flood 5250 ft^3/s 856

Peak-Flow Statistics Citations

Gotvald, A.J., Barth, N.A., Veilleux, A.G., and Parrett, Charles,2012, Methods for determining magnitude and frequency of floods in California, based on data through water year 2006: U.S. Geological Survey Scientific Investigations Report 2012–5113, 38 p., 1 pl.

(http://pubs.usgs.gov/sir/2012/5113/)

Region ID: CA Workspace ID: CA20201125164322594000 Clicked Point (Latitude, Longitude): 35.26959, -115.52048 Time: 2020-11-25 08:43:40 -0800

StreamStats Report - Lanfair Road Sta + 0 to +

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 45.1 square miles 0.04 173

Peak-Flow Statistics Flow Report[2012 5113 Region 6 Desert]

PIl : Prediction Interval-Lower, PIu: Prediction Interval-Upper, SEp: Standard Error of Prediction, SE: Standard Error (other -- see report)

Statistic Value Unit SEp

2 Year Peak Flood 70.8 ft^3/s 214

5 Year Peak Flood 412 ft^3/s 226

10 Year Peak Flood 1040 ft^3/s 248

25 Year Peak Flood 2770 ft^3/s 298

50 Year Peak Flood 5220 ft^3/s 357

100 Year Peak Flood 9280 ft^3/s 444

200 Year Peak Flood 15600 ft^3/s 575

500 Year Peak Flood 29400 ft^3/s 856

Peak-Flow Statistics Citations

Gotvald, A.J., Barth, N.A., Veilleux, A.G., and Parrett, Charles,2012, Methods for determining magnitude and frequency of floods in California, based on data through water year 2006: U.S. Geological Survey Scientific Investigations Report 2012–5113, 38 p., 1 pl.

(http://pubs.usgs.gov/sir/2012/5113/)

Region ID: CA Workspace ID: CA20201125165348422000 Clicked Point (Latitude, Longitude): 35.05287, -115.16511 Time: 2020-11-25 08:54:08 -0800

Appendix B – Dome Fire Emergency Stabilization Plan

Emergency Stabilization Plan

Dome Fire Mojave National Preserve, California

Submitted by: ______________________________________ Date:______________________ Mike Gauthier, Superintendent

September 2020

PAGE INTENTIONALLY BLANK

Dome Fire 1

Unit Summary Information Unit Name Mojave National Preserve Unit Identifier MOJA NPS Region Pacific West

Fire Summary Information Fire Name Dome Fire Fire Number CA-MNP-012356 Fire Code NFA4 Detection Date/Cause 8/15/2020 1522 PDT

Lightning Date Contained 8/26/2020 Acreage NPS= 43273

Account Number(s) Emergency Stabilization, FY20 Fund XP112585 Cost Center PPPW Functional Area PF220ES85.RM0000

WBS PF.FENFA4020.00.1

Team Members Position Name & Affiliation Vegetation Drew Kaiser, Mojave National Preserve GIS Scott Sheppard, Bureau of Land Management RRED Mary Ellen Miller, Michigan Tech Research Institute Wildlife Neal Darby, Mojave National Preserve Cultural Matt Caire, Mojave National Preserve Facilities Greg Bowman, Mojave National Preserve Haz Mat Gary Riley, Pacific West Region Wildlife Neal Darby, Mojave National Preserve Hist Structures Ashley Phillips, Lassen Volcanic National Park Resource Management Debra Hughson, Mojave National Preserve Technical Assistance Nelson Siefkin, Pacific West Region Facilitation Chris Holbeck, Midwest Region

Dome Fire 2

EXECUTIVE SUMMARY

Introduction

This Emergency Stabilization (ES, also called Burned Area Emergency Response [BAER]) plan has been prepared for the Dome Fire at MOJA.

The fire burned approximate 43,273 acres in the preserve from 8/15/2020 to 8/24/2020 in an area of dense Joshua tree forest.

Policy and Guidance

The plan was developed in accordance with Department of the Interior and National Park Service (NPS) policy and guidance, including:

Office of Wildland Fire (OWF) Policy Memorandum 2016-01 (Post-Wildfire Recovery Program and Policy Changes);

Interagency Standards for Fire and Fire Aviation Operations;

NPS Reference Manual 18 (Chapter 18);

NPS Wildland Fire & Aviation Management Business Rules;

Interagency Burned Area Emergency Response Guidebook (Version 4.0)

The primary objective of the BAER program is to assess the need for and prescribe cost effective post-fire stabilization measures necessary to protect human life, property, and critical natural and cultural resources. BAER is conducted in accordance with approved land management plans and policies, and all relevant federal, state and local laws and regulations.

BAER is intended to address imminent (<1 year) threats caused by wildfire; it is not responsible for long-term management or rectifying deficiencies that existed prior to the fire. Department of the Interior and NPS BAER policy echoes federal wildland fire policy regarding protection priorities: human safety is first, and property and critical natural and cultural resources are ranked based on the relative values to be protected, commensurate with emergency stabilization costs.

The basis of the BAER assessment process is identifying, evaluating, and protecting, repairing or replacing values at risk (VARs)—human safety, properties, capital improvements and natural and cultural resources—located within and downstream of burned areas, and impacted by fire and/or vulnerable to post-fire conditions. When evaluating a given VAR, consideration is given to the significance of the value, probability of further damage occurring, the magnitude of potential consequences, and the feasibility to mitigate.

Local Management Plans

Pertinent approved land and resource management plans and other documents that guided the preparation of this plan include:

Dome Fire 1

DOME FIRE

Appendices

Dome Fire 2

APPENDIX A—HYDROLOGIC MODELING

Watershed Modeling (AGWA-KINEROS) Watershed modeling is used to estimate post-fire runoff response. Storm runoff and erosion modeling is a tool used by BAER teams to illustrate risk to life, infrastructure and natural and cultural resources.

The AGWA/KINEROS2 modeling framework uses readily available geospatial datasets to provide model inputs for rapid assessment model runs. This tool uses a Digital Elevation Model (USGS-DEM) to break a watershed into modeling elements, which are then intersected with soil (SSURGO/STATSGO) and land cover (MLRC-NLCD) geospatial layers to derive requisite model input parameters (Goodrich et al, 2005). Once parameters are assigned, the KINEROS2 runoff and erosion model determines storm runoff response for both an unburned and a burned condition to get a sense of the anticipated change. AGWA is designed to provide rapid qualitative estimates of runoff and erosion relative to landscape change. It cannot provide reliable quantitative estimates of runoff and erosion without careful calibration. It is also subject to the assumptions and limitations of its component hydrologic models (Goodrich et al, 2005).

Field observations, scientific literature, and professional judgement further inform model inputs. The following modeling results were prepared by a hydrologist at a remote location, with local knowledge and on the ground observations provided by Park staff.

The Dome fire primarily burned the Cima Dome, meaning that the areas of concern are mostly hillslope features, with only a couple of areas that qualify as a watershed.

PPrecipitation frequency and distribution NOAA Atlas 14 Precipitation Frequency Estimates were the driving inputs for the model.

A one hour duration was chosen for the design storm. One hour approximates the duration of a typical summertime convective storm in the region (monsoon), which is viewed as the imminent threat for post-fire flooding in the southwest. The 10 and 25 year return period storms were chosen to give a range of outcomes based on the likelihood of storm occurrence in any given year. Lesser amount and less intense rainfall is not expected to produce storm runoff at Cima Dome.

Table 1. Design storm depths provide by NOAA atlas 14

Duration 10 year return period (1 in 10 chance)

25 year return period (1 in 25 chance)

1 hour 1.18” (30mm) 1.57” (40mm)

Rainfall was applied only to the burned areas, which covered the entire drainage basins for the Kessler Springs area and the Mojave Cross-Cima Road drainage areas and large portions of hillslopes at the other areas of interest.

Results The AGWA tool was used to model post-fire watershed/hillslope response to rainfall, and provides estimates for increases to clear water flows, as well as estimates for increases to erosion. The percent change or magnitude change should be viewed as “the result” for decision making.

Dome Fire 3

Figure 1. Shows an overview of the Cima Dome fire and the affected drainage areas and hillslopes

CCima Road Culvert The Park housing facility at Kessler Spring was identified as a Value At Risk, with increased peak flow rates through the Cima road culvert being the source of the risk. This location was modeled at a couple of different spatial scales with the AGWA/K2 modeling scheme, the immediate hillslope presented in this section (46 acres) and a larger hillslope (353 acres) presented in the next section. This section shows potential increases to peak flow rates, sediment delivery will be addressed in the following section.

Table 2. Peak flow rates at the culvert on Cima road Peak Runoff Rate (cfs) Wash/flowpath Rainfall Pre-fire Post-fire % change Magnitude change Cima Road Culvert and Kessler Springs Ranch

10 year 1 hour

4 31 624 7

25 year 1 hour

41 72 76 2

Table 2 and Figure 2 show the relative change in peak flow rates due to the Dome fire. The anticipated increase in runoff in response to the 10 year 1 hour storm is fairly large at a 7 fold increase. However, the anticipated change in runoff for the 25 year 1 hour storm is much less (at double the flow).

Considering the similarity in response for the post-fire 10 year storm event (30mm) and the pre-fire 25 year storm event (40mm), it can be hypothesized that the sort of flow that had a 1/20 some chance of happening prior to the fire, now has closer to a 1 out of 10 chance of occurring due to the Dome fire.

Dome Fire 4

Figure 2. Hydrographs showing the outflows at the box culvert on Cima road near Kessler springs in pre and post-fire landscape conditions resulting from the design storms in Table 1.

Dome Fire 5

Figure 3. Shows the Cima Road culvert location and drainage areas for the dominant washes flowing NW and SE from the Dome Fire area. Percent change in runoff behavior for sediment discharge from hillslopes and peak flow rates for wash segments is displayed for the Kessler and Mojave Cross drainage areas and the expected peak flow rates at the culvert.

Kessler Drainage Area Looking at the larger drainage area, and the hillslope (modeling element) that contains the Cima road culvert and the Kessler Spring housing complex, it can be seen that the largest relative change is for sediment delivery resulting from the 10 year 1 hour storm event (Table 3). The larger ‘raw’ numbers in the Pre and Post-fire columns can be attributed to the difference in spatial scale when comparing results in Tables 2 and 3.

Table 3. Erosion and peak runoff rate modeling results for Kessler Drainage Area Erosion (lbs/ac) Hillslope - VAR Rainfall Pre-fire Post-fire % change Magnitude change Cima Road Culvert and Kessler Springs Ranch

10 year 1 hour

110 889 707 8

25 year 1 hour

917 3041 232 3

Peak Runoff Rate (cfs) Hillslope - VAR Rainfall Pre-fire Post-fire % change Magnitude change Cima Road Culvert and

10 year 1

77 260 238 3

Dome Fire 6

Kessler Springs Ranch

25 year 1

220 643 192 3

MMojave Cross-Cima Road Wash Crossing Drainage Area This is one of the more defined drainage areas affected by the Dome Fire (Figure 3). It contains the Mojave Cross VAR. The Cima Road parallels the prominent wash for approximately 1.5 miles, and has at least one crossing/interaction.

Table 4. Erosion and peak runoff rate modeling results for the Mojave Cross-Cima Road Wash Crossing Drainage Area Erosion (lbs/ac) Hillslope - VAR Rainfall Pre-fire Post-fire % change Magnitude change…