Hydraulics_Report.pdf

FINAL HYDRAULIC REPORT

GUIDOTTI PEDESTRIAN BRIDGE REPLACEMENT OVER EL TORO CREEK

FORT ORD NATIONAL MONUMENT, CA

CA BLM 19041(2)

Prepared by:

Laura Girard

Technical Services Hydraulic Engineer

Central Federal Lands Highway Division

February 2015 ii

TABLE OF CONTENTS

Introduction

Project Background and Objectives

Site Visit

Bridge Design Criteria

Project Data

Project Area Description

Hydrologic Analysis

Hydraulic Analysis

Proposed Condition Model

Scour Analysis

Abutment Protection

Summary of Recommendations

References

LIST OF TABLES

Table 1. El Toro Creek Peak Flows (Monterey County FIS) Table 2. HEC-RAS Input Values for proposed Bridge Configuration Table 3. Hydraulic Modeling Results for the Proposed Bridge Table 4. Scour depths for the proposed bridge. (*RESULTS NOT FINAL)

LIST OF FIGURES

Figure 1. Guidotti Bridge – CA BLM 19041(2) Project Location Map Figure 2. Guidotti Bridge – CA BLM 19041(2) Close-up Location Map Figure 3. Approximate 4 foot headcut downstream of Guidotti Bridge (February 2010 Figure 4. Plan view of HEC-RAS hydraulic model cross section locations Figure 5. Water Surface Profiles for Existing and Alternative Bridge Spans Figure 6. Proposed Upstream Bridge Cross Section

APPENDICIES

Site Visit Photos, 2010 Fort Ord Roadways Drainage Report, Hydraulic Analysis Results

INTRODUCTION

This report provides an overview of the key project elements and summary of the hydrologic and hydraulic analyses that resulted in the selected proposed bridge design. The intent is to provide information that supports the selected bridge alternative and alignment for design.

PROJECT BACKGROUND AND OBJECTIVES

The Central Federal Lands Highway Division with cooperation with the Bureau of Land Management, plan to replace the existing Guidotti Bridge. The bridge is located on Guidotti Road, approximately 1/4 mile from the Badger Hills Trailhead visitor parking lots. Guidotti Bridge is a 125 foot long, 3 span, filled concrete spandrel arch structure that crosses El Toro Creek. The middle span was constructed in 1908 and 2 exterior spans constructed in 1911, as indicated by the stamps imprinted on the fascia of the arch.

The arches are supported by shallow spread footings that have been intermittently exposed along the bottom along the piers. The bridge railing consists of solid concrete vertical parapets. The width of the structure is approximately 22’; the structure is skewed about 15 degrees to the 50-year flow event. At the ends of the bridge, concrete wingwalls extend from the arch faces at varying skews and lengths. The bridge has failed due to scour and subsequent settlement of the shallow spread footings. The 2009 bridge inspection report mentions seismic activity as a possible contributor to failure of the bridge. Refill has occurred below the footings to restore grade where settlement “dropped” the arch segments.

The existing bridge is currently a one-lane bridge used by pedestrians, bikers, and equestrians to access recreation trails of Fort Ord National Monument. The inspection report classifies the bridge as critically deficient and recommends replacement; as the condition of the structure continues to deteriorate it will become necessary to close the structure to all traffic.

A previous drainage study was conducted in 2010 for this site by CH2MHill on behalf of CFLHD. This earlier study included a hydrologic analysis to determine peak flows at the existing bridge. Additionally, a hydraulic model was developed to assess the capacity constraints of the existing bridge. The hydrologic analysis and model was utilized as part of this study to identify potential bridge replacement alternatives to meet the design criteria. The 2010 Fort Ord Roadways Drainage Report by CH2MHill is included in

Appendix B.

The objective of this project is to evaluate the existing hydraulic conditions and design a new bridge with sufficient capacity to meet the design criteria. For reference, the project is located in Fort Ord National

Monument approximately 6.7 miles east of Del Rey Oaks, California. Figures 1 show the project location and surrounding area and Figure 2 presents an aerial map of the site provided by the BLM. The site can be referenced by the following geographic coordinates:

Lat. 36.582981°, and Long. -121.716017°.

Figure 1. Guidotti Bridge – CA BLM 19041(2) Project Location Map.

Figure 2. Guidotti Bridge – CA BLM 19041(2) Close-up Location Map.

Guidotti Bridge

SITE VISIT

The Central Federal Lands Highway Division (CFLHD) project team visited the project site on February

19, 2014 to review the existing site conditions and define the scope of work for the design of a replacement bridge. Photos from the site visit are included in the Appendix A.

BRIDGE DESIGN CRITERIA

Guidotti Road serves as a hiking, equestrian, and biking trail which is gated at the Badger Hills Trailhead parking lot from public vehicular use. CFLHD design standards for bridged waterways are a 50-year flood design, with a minimum of 2 ft of freeboard below the low chord. Stability design is for the 100-yr flood with a 500-yr check flood (SF≥1).

PROJECT DATA

Detailed mapping information of the project reach was collected as part of the earlier 2010 study. IN 2014 the CFL survey team provided supplemental ground surveys near the bridge that was supplemented into the older hydraulic model. The mapping products were provided by the survey team.

PROJECT AREA DESCRIPTION

The bridge is located on Guidotti Road, approximately 1/4 mile from the Badger Hills Trailhead visitor parking lots. Guidotti Bridge is a 125 foot long, 3 span, filled concrete spandrel arch structure that crosses

El Toro Creek. The middle span was constructed in 1908 and 2 exterior spans constructed in 1911, as indicated by the stamps imprinted on the fascia of the arch. The arches are supported by shallow spread footings that have been intermittently exposed along the bottom along the piers. The 2014 field site visit noted undermining of existing bridge footings at the middle arch span and large settlement of this section.

The roadway crosses the channel at about a 15 degree angle during the 50-yr event and constricts flow through the existing bridge opening. For smaller events the skew is upwards of 45 degrees. At the ends of the bridge, concrete wingwalls extend from the arch faces at varying skews and lengths.

The active, ephemeral channel is contained in the middle arch section. The channel in the south and north arches contain a floodplain bench that is approximately 6 ft higher than the main channel.

Main channel bed material appears to be coarse sand. North arch also has silt/sand sediment in bed.

Side arch channel beds are composed of sand and silt. High water marks were observed one the outside of the side arches at about 1.5 ft higher than the bed.

There is heavy vegetation in the channel immediately upstream of the bridge with 6-8 saplings directly at the upstream face of the bridge and in the active channel. Downstream has less severe vegetation in the channel (mostly 12-18 inch plants).

A 4 foot head cut downstream of bridge is about 300- 350 downstream of bridge; much closer than the

1000 ft indicated in the 2010 Geomorphic Report. At present debris jam is holding head cut, see Figure 3.

Figure 3. Approximate 4 foot headcut downstream of Guidotti Bridge (February 2010).

HYDROLOGIC ANALYSIS

Previous hydraulic studies completed by consultants (CH2MHill 2010) evaluated the existing bridge capacity. The previous study included a review of published hydrology data for the drainage basin from the Monterey County Floodplain Management Plan and published FEMA flow data. Ultimately, they concluded that the FEMA flow data was higher and produced the most conservative results. A summary of hydrologic methods and results is included in Appendix B and a summary of the FEMA discharges are below in Table 1.

Flood Event Peak Discharge (cfs)

2-year 126

10-year 356

50-year 1,033

100-year 1,642

500-year 2,844

Table 1. El Toro Creek Peak Flows (Monterey County FIS).

HYDRAULIC ANALYSIS

Hydraulic modeling of Guidotti Bridge was performed using the Hydrologic Engineering Center River

Analysis System (HEC-RAS) version 4.1.0 published by the US Army Corps of Engineers. Existing conditions of Guidotti Bridge were assessed in 2010, details can be found in the attached drainage study.

PROPOSED CONDITION MODEL

Based on coordination with the CFL bridge design team, the proposed replacement bridge is an approximately 100 feet long single span structure. A single span structure is preferred to minimize construction within the stream channel while maximizing available flow area. The 2H:1V sloping abutments are aligned normal to the bridge centerline. Total bridge width of 16’-0” is proposed. Based on a 2014 field survey, cross sections in the 2010 existing conditions model were modified immediately upstream and downstream of the proposed bridge. The existing bridge was removed from the model and the proposed conditions entered including 2H:1V sloping abutments. The proposed bridge configuration was modeled using a proposed low chord value provided by the bridge team and summarized in Table 3 below.

Bridge Low Chord Bridge Width (ft)

220.7 16.0

Table 2. HEC-RAS Input Values for proposed Bridge Configuration.

Values from Table 1 were used to model a mixed flow regime of the proposed bridge configuration. The main channel was modeled with a Manning’s n value of 0.035 while the overbanks are modeled with a

Manning’s n value of 0.05 and the upper floodplain with a value of 0.08. Boundary conditions for upstream and downstream were determined by normal depth calculations with slopes of 0.01 and 0.013 feet per foot, respectively

The model limits extended roughly 150 ft upstream of the bridge and 200 ft downstream. A total of 13 cross sections were extracted from the project topographic mapping to represent the channel geometry through the reach. The locations of the cross sections are shown below in Figure 3.

Figure 4. Plan view of HEC-RAS hydraulic model cross section locations.

Table 3 presents the hydraulic modeling results for the cross section immediately upstream of the proposed Guidotti Bridge. The. The resulting water surface elevation plots for each flow are shown below in Figure 4 and the 50-yr and 100-yr design water surface elevations at the bridge are shown below in Figure 5.

Flow Profile Flow Rate

(cfs) Water Surface

Elevation Energy Gradeline

Elevation Channel

Velocity (ft/sec.)

2 Year 126 212.50 212.67 3.32

50 Year 1,033 215.96 216.44 5.58

100 Year 1,642 217.39 217.87 5.85

500 Year 2,844 219.63 220.14 6.32

Table 3. Hydraulic Modeling Results for the Proposed Bridge.

Figure 5. Water Surface Profiles for Existing and Alternative Bridge Spans.

Bridge low chord elevation = 220.7 ft

Figure 6. Proposed Upstream Bridge Cross Section.

The proposed bridge configuration will safely pass a 100-yr flood event and provide 2 ft of freeboard in the 50-yr event, based on a low chord elevation of 220.7 ft. By removing the existing concrete arch bridge, the two wide pier elements and the spandrel from the flow path hydraulic capacity is greatly improve, allowing for a shorter bridge than the existing.

SCOUR ANALYSIS

A scour analysis was performed using the results from the HEC-RAS model, and the 2014 survey information. Bed material was conservatively assumed to be 2 mm sand. Hydraulic analysis indicates that the hydraulic capacity of the new bridge will be adequate to pass the 50-year flow event and will be stable for the 100-year flow event.

Scour analysis for the proposed Guidotti Bridge was estimated using three methods presented in HEC 18

(2012):

1. Clear water contraction scour based on Laursen’s equation (1963)

2. NCHRP abutment scour approach

**TBD The total scour depth estimates are summarized below in Table 4. The total scour depth is estimated at 15 feet at an elevation of ** feet.

Event Contraction Scour

(ft)

Abutment Scour (ft)

Left Right

100-yr 0 10 4

500-yr 0 14 15

Table 4. Scour depths for the proposed bridge. (*RESULTS NOT FINAL)

Proposed berm elevation for

190 ft span bridge (5669.0 ft)

Existing berm

ABUTMENT PROTECTION

Riprap, to be placed along the abutments, was selected based on the methodology presented in HEC-23

Volume 2, Design Guideline14.

The riprap around the bridge abutments should be toed into the channel bed by extending the veneer 3 feet below the bed elevation and extending it horizontally into the channel 8 feet. Due to environmental concerns the horizontal extent of the riprap was decreased form recommended. The decrease in extent is accounted for by an increase in depth, thereby allowing for the same volume of rock to be placed.

SUMMARY OF RECOMMENDATIONS

Hydraulic capacity of the new structure was based on the following criteria:

Q50 design flood with at least two feet of freeboard

Passing Q100

By removing the existing concrete arch bridge, the two wide pier elements and the spandrel are removed from blocking the flow path, thus improving hydraulic capacity and allowing for a shorter bridge than the existing. Based on preliminary hydraulic analysis a proposed structure length of 100’ will allow for 2 feet of freeboard for the 50-yr event and will pass the 100-yr event. A shorter bridge could potentially meet the above hydraulic requirements but may not be preferable from an environmental impact due to the increased foot print of the fill areas in the riparian areas adjacent to the structure.

It is recommended that the existing bridge be removed and spill-through, riprap abutments be designed and constructed in conjunction with a proposed 100 ft single-span design. The abutments would be designed to provide up to 100-yr scour and erosion protection and Guidotti Bridge would have the capacity to safely pass the 50-year flood event with 2 ft of freeboard.

Bridge Configuration

Recommended bridge span – 100 ft (distance between abutments)

Minimum low chord elevation – 220.7 ft

Riprap Abutment Protection

2H:1V Sloping abutment protection

Class III riprap

Foundation Design

The 100-year design scour elevation is ** ft.

Bridge pier and abutment foundations should be designed to account for an unsupported length above elevation ** ft.

REFERENCES

Federal Highway Administration (2008) “Project Development and Design Manual” Federal Lands

Highway Division. US Department of Transportation. Chap 7.

Federal Highway Administration HEC-18, Evaluating Scour at Bridges, Fifth Edition, April 2012.

Federal Highway Administration HEC-23, Bridge Scour and Stream Instability Countermeasures:

Experience, Selection, and Design guidance-third Edition, Volume2, September 2009.

US Army Corps of Engineers, HEC-RAS v 4.1.

US Geological Survey (1992) “Guide for Selecting Manning’s Roughness Coefficients for Natural

Channels and Flood Plains” USGS Water Supply Paper 2339. US Dep. of Interior. Denver, CO.

APPENDIX A

Site Visit Photos

Figure A.1. Upstream bridge face.

Figure A.2. Downstream main channel.

Figure A.3. Scoured and failed shallow footing pier.

Figure A.4. Downstream headcut.

APPENDIX B

2010 Fort Ord Roadways Drainage Report

TECHNICAL MEMORANDUM CH2MHILL

Fort Ord Roadways (Low Water Crossing) Drainage Report

PREPARED FOR: Nate Allen/ CFLHD

J} PREPARED BY: Doug Stewart/ CH2M HILL

DATE: March 30, 2010

PROJECT NUMBER: 399743.07.FR.HY

Introduction The purpose of this Technical Memorandum is to document the drainage design analyses and results for the Fort Ord Low Water Crossing project. A hydrologic analysis was performed to determine the 2-, 10-, 50-, 100-, and 500-year peak flows at the existing bridge along Guidotti Road over El Toro Creek, in Monterey County, California, approximately 6.7 miles east of Del Rey Oaks. The existing bridge has failed and will be replaced with a low water crossing. The peak flows were then used in a hydraulic analysis to determine the depth of flow over the low water crossing. The 10-year design storm was chosen to design the extents of concrete for the new low water crossing. There will be no additional roadway improvements in the vicinity of the low water crossing.

The Ft. Ord Roadways (Low Water Crossing) project is funded using ARRA stimulus money for deferred BLM maintenance projects. Due to the scope of these projects and limited available funding, the hydrologic and hydraulic analyses were limited to information collected on a site assessment and reasonable construction approach to meet the goals of this project.

Hydrology Published hydrology data was first used to establish peak discharges at the low water crossing location for the 10-,50-, 100-, and 500-year flows in El Toro Creek. The data was obtained from the Monterey County Floodplain Management Plan (2003). Established discharges were obtained at the San Benancio Road crossing 2000 feet u pstream and the USGS Gage Station 21,000 feet downstream of the low water crossing location. A linear relationship was assumed between the distance/ drainage area/ and peak flows. Table 1 shows the results of the estimated flows. A calculation summary is attached to this technical memorandum.

The 2-year flow for El Toro Creek was not presented in published hydrology data. To determine the 2-year flow, a ratio of the 2-year flow with the 100-year flow was determined through research of other published data. It was determined that the 100-year flow is approximately 14 times the 2-year flow resulting in a 2-year flow of 103 cfs. The 2-year flow is also presented in Table 1.

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FORT ORD ROADWAYS (LOW WATER CROSSING) –

DRAINAGE REPORT

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TABLE 1

Calculated Peak Discharges (cfs) at Low Flow Crossing based on County data

2-year 10-year 50-year 100-year 500-year

103 248 887 1,444 2,476

Although FEMA coordination was not part of the scope of services, CH2M HILL researched published FEMA flow data for El Toro Creek. A common design point was found in both the FEMA documents and the Monterey County Floodplain documents at Gage Station 11152540 21,000 feet downstream of the low water crossing. It was discovered that the FEMA flow data were higher than the County data. CH2M HILL increased the design flows at the low water crossing shown in Table 1 proportionate to the increase at the gage station.

Table 2 shows the calculated peak discharges at the low flow crossing based on the FEMA data. See attachments to this technical memorandum for determination of these flows.

TABLE 2

Calculated Peak Discharges (cfs) at Low Flow Crossing based on FEMA data

2-year 10-year 50-year 100-year 500-year

117 356 1,033 1,642 2,844

To be conservative, and to provide data acceptable to FEMA for future use, CH2M HILL used the data in Table 2 to perform the hydraulic analysis for the low flow crossing design.

Hydraulics

Hydraulics of the flow at the Fort Ord Low Water Crossing were analyzed using the United States Army Corps of Engineers HEC-RAS (Hydrologic Engineering Center River Analysis System) model. HEC-RAS is designed to perform one-dimensional hydraulic calculations for channel systems. The one-dimensional river analysis component used for the analysis of the Fort Ord Low Water Crossing was the steady flow water surface profile computations.

Cross sections were cut in a digital terrain model (DTM) based on survey data. Cross sections were developed upstream and downstream of the low water crossing and input into the model. Runs were performed for existing and proposed conditions. The existing conditions model includes the existing triple span arch culvert while the proposed conditions model uses a modified roadway and pavement section with a concrete bottom for a low water crossing.

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Table 4 shows a comparison of 100-year water surface elevations between the existing and proposed conditions for various cross section modeled using HEC-RAS. The output files for the existing and proposed conditions HEC-RAS models are attached at the end of this report.

Low Water Crossing

The low water crossing will be constructed of reinforced concrete up to the 10-year water surface elevation (214.32 feet) flowing in El Toro Creek. The vertical curve length of the low water crossing will be 119.18 feet. The horizontal alignment of the low water crossing will match the alignment of the existing bridge. The road at each end of the low water crossing will tie back into the existing road above the 10-year elevation. The low water crossing will have concrete cutoff walls on all sides of the structure. The downstream cutoff wall will be at a depth of 4 feet below the slab and the other three walls will be 2 feet below the slab.

Class 3 riprap will be placed on the downstream side of the slab below the existing channel bed elevation. Placing riprap adjacent to the structure will minimize scour. Native earth fill will be placed over the riprap to match the existing channel bed. Class 3 riprap will also be

TABLE 3

Summary of Flow Depths over the Low Water Crossing using FEMA data

Return Period (year) Flow Depth (ft) Flow Width (ft)

*18 inches of water 1.50 73.85

2 2.45 92.84

10 4.06 118.78

25 5.77 143.01

50 6.40 151.94

100 7.58 167.74

500 9.39 194.93

* 18 inches of water depth is the maximum depth before the crossing should be closed to traffic

TABLE 4

Comparison of 100-year Water Surface Elevations (WSEL) for Existing and Proposed Conditions

HEC-RAS Cross Section Existing WSEL Proposed WSEL

14.1154 (downstream) 213.13 213.13

175.6977 216.88 216.88

187.9316 216.54 216.79

201.4855 217.66 217.45

209.144 (low water crossing) 217.85

216.802 (low water crossing) 217.84

224.4612 217.79 217.69

274.0892 (upstream) 217.91 217.81

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placed up to the 25-year water surface elevation on the disturbed embankments downstream of the structure for stabilization. The riprap will extend from the edge of the downstream cutoff wall for a distance of approximately 22 feet downstream. Central Federal Lands requires that low water crossings be stabilized to the 25-year peak flow event.

According to HEC-15 calculations for riprap in channels, Class 3 riprap provides sufficient shear force to withstand the 25-year flows in El Toro Creek. Class 3 riprap will be placed up to the 25-year water surface elevation along the channel downstream of the low water crossing. No additional stabilization is required along the roadway beyond the extents of the 10-year water surface because the 25-year peak flow velocities in the overbanks are less than 3 feet per second.

Erosion and Sediment Control

Silt fence is to be placed on both the east and west sides of El Toro Creek upstream of the crossing. Sediment logs should be placed along the ditches directly north of Guidotti Road and any areas that are disturbed during construction must be re-seeded. After the channel flows are diverted around the construction area, a rock check dam will be placed in the channel downstream of the crossing to capture sediment from storm events during construction.

Surface Water Diversion and Dewatering

Base flows and stormwater surface flows shall be diverted around the construction area by pumping or other means as requested by the Contractor and approved by the CO. Pumping flows around the construction area would minimize impacts to vegetation and ground disturbance caused by a temporary diversion channel or pipe. Groundwater in the vicinity of the low water crossing footings shall be pumped to a dewatering discharge area where sediment will be allowed to settle out of the flow prior to discharging back into the creek.

Sand bags can be used to detain the flows and aggregate can be placed at the discharge point to minimize erosion or scour from the pump discharge. The Contractor shall follow all dewatering permit requirements.

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ATTACHMENTS

Photos

Project Location Map

Hydrology Data

HEC-RAS

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Photos

Guidotti Road - looking west

El Toro Creek – looking upstream

Guidotti Road - over the existing bridge

Existing Bridge – to be replaced

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Hydrology Data

From the Monterey County Floodplain Management Plan (2003):

El Toro Creek Peak Discharges (cfs)*

Location Drainage Area (Square Miles) 10-year 50-year 100-year 500-year

At San Benancio Road 23.4 240 860 1,400 2,400 At USGS Gage (Downstream of Highway 68) 31.9 400 1,340 1,900 3,500

At confluence with Salinas River 41.4 400 1,390 2,000

Source: Flood Insurance Study, Monterey County, California (September 27, 1991)

The Low Water Crossing is between San Benancio Road and the USGS Gage Station (Downstream of Highway 68).

Distance from San Benancio Road = +/- 2,000 feet, A = 23.4 sq-miles

Distance from USGS Gage Station = +/- 21,000 feet, A = 31.9 sq-miles

Assuming a linear relationship between distance and drainage area:

000,21

9.31

000,23

4.239.31 X−

14.24) ( miXsitetoA ==

Assume a linear relationship between drainage area and peak discharge:

BenancioSanpsitep QQ 4.23

14.24

El Toro Creek Peak Discharges (cfs)

Flooding Source and Location Drainage Area (Square Miles) 10-year 50-year 100-year 500-year

El Toro at the low water crossing 24.14 248 887 1,444 2,476

To determine the 2-year peak flow, determine ratio of the 100-year peak flow to the 2-year peak flow. From published data:

07.14

100 = Q cfs

Q site 103 07.14

444,1

07.14

2 ===

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From FEMA Flood Insurance Study (effective 2009):

El Toro Creek Peak Discharges (cfs)

Flooding Source and Location Drainage Area (Square Miles) 10-year 50-year 100-year 500-year

El Toro Creek Gage (11152540) 31.9 574 1,560 2,160 4,020

Adjustment Ratios between FEMA peak discharges and the County peak discharges at Gage 11152540

435.1

10 ==

County

FEMA

Q

Q 164.1

50 ==

County

FEMA

137.1

100 ==

County

FEMA

Q

Q 149.1

500 ==

County

FEMA

Multiplying the County peak discharges by these values arrives at the FEMA-adjusted flows at the low water crossing as shown below.

cfsQQ CountyFEMA 356435.1248435.11010 =×=×= cfsQQ CountyFEMA 033,1164.1887164.15050 =×=×= cfsQQ CountyFEMA 642,1137.11444137.1100100 =×=×= cfsQQ CountyFEMA 844,2149.12476149.1500500 =×=×=

El Toro Creek Peak Discharges (cfs)

Flooding Source and Location Drainage Area (Square Miles) 10-year 50-year 100-year 500-year

El Toro at the low water crossing 24.14 356 1,033 1,642 2,844

To determine the 2-year peak flow, determine ratio of the 100-year peak flow to the 2-year peak flow. From published data:

07.14

100 = Q

Q cfs

Q Q site 117

07.14

07.14

2 ===

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A log-normal distribution of FEMA peak flow values at the project location was created to determine the 25-year peak flow. The following table presents the FEMA peak flows used for this study.

Return Period (years) Q (cfs)

10 356

50 1033

100 1642

500 2844

The following figure shows the log-normal distribution of FEMA peak flow values.

The x-axis, return period, is presented on logarithmic scale while the y-axis, peak discharge, is presented on a standard scale. By applying a logarithmic trend line to the dataset, the 25-year peak flow can be determined.

Log Normal Distribution to Determine 25-Year Peak Flow y = 643.37Ln(x) - 1271.1

R2 = 0.9753

1 10 100 1000

Return Period (years)

Q c fs

The trend line shows that the relationship between discharge and return period is:

( ) 1.127137.643 −= xLny

( ) cfsLnQ FEMA 8001.12712537.64325 =−=

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

N

CA BLM 19006(1)

FORT ORO FUELBREAK

LEVEL 3 ROAD REPAIRS

Project CA BLM 19006(1)

' I ,;;;ONTEREY CA

, 13.4mi

Project Area

1 .5 0 2

SCALE IN MILES

CH2MHILL

SAllNASCA

4.7 ml

Calera Creek ----

MAP SCALE 1 II = 500'

500 1000

FEET

PANEL 0354G

FIRM

FLOOD INSURANCE RATE MAP

MONTEREY COUNTY,

CALIFORNIA

AND INCORPORATED AREAS

PANEL 354 OF 2050

(SEE MAP INDEX FOR FIRM PANEL LAYOUT)

CONTAINS:

COMMUNITY

MONTEREY CO UNTY 060195 0354 G

Notice to User: The Map Number shown below should be used when placing map orders; the Community Number shown above should be used on insurance applications for the subject community.

MAP NUMBER

06053C0354G

EFFECTIVE DATE

APRIL 2, 2009

Federal Emergency Management Agency

METE

This is an official copy of a portion of the above referenced flood map. It was extracted using F-MIT On-Line. This map does not reflect changes or amendments which may have been made subsequent to the date on the title block. For the latest product information about National Flood Insurance Program flood maps check the FEMA Flood Map Store at www.msc.fema.gov

1. AND

VOLUME 2 OF 3

MONTEREY COUNTY,

CALIFORNIA

AND INCORPORATED AREAS

COMMUNITY NUMBER

060196 060197

COMMUNITY NAME

CARMEL-BY-THE-SEA, CITY OF

DEL REY OAKS, CITY OF

GONZALES, CITY OF

GREENFIELD, CITY OF

060198 060446 Monterey County

KING CITY, CITY OF

MARINA, CITY OF

MONTEREY, CITY OF

MONTEREY COUNTY

(UNINCORPORATED AREAS)

PACIFIC GROVE, CITY OF

SALINAS, CITY OF

SAND CITY, CITY OF

SEASIDE, CITY OF

SOLEDAD, CITY OF

060199 060727 060200

060195 060201 060202 060435 060203 060204

EFFECTIVE:

APRIL 2, 2009 ., .,

Federal Emergency Management Agency

FLOOD INSURANCE STUDY NUMBER

06053CV002A

TABLE 4- SUMMARY OF DISCHARGES- continued

DRAINAGE

FLOODING SOURCE AREA PEAK DISCHARGES (cfs}

AND LOCATION (sg. miles} 10-PERCENT 2-PERCENT 1~PERCENT 0.2-PERCENT

DEL MONTE LAKE

Total inflow 2.9 105 285 340 550 At Josselyn Canyon Creek 1.3 40 110 145 250 At State Highway 68 0.8 45 100 120 200

Canyon

EAST BRANCH

GONZALES SLOUGH

AfU.S. Highway 101 2.3 55 135 195 260

EL ESTERO LAKE

Total inflow 4.2 210 460 550 930 East inflow 2.4 90 220 270 465 West inflow 1.2 60 130 160 270

EL TORO CREEK

At E1 Toro Gage 31.9 574 1,560 2,160 4,020

(11152540)

ELKHORN SLOUGH

At State Highway 1 48.7 3701 9601 1,2001 2,3301

At Elkhorn Road 34.0 475 i ,370 1,740 3,460 At Maher Road 22.0 410 1,200 1,530 3,021 At U.S. Highway 101 4.4 120 325 400 760

GABILAN CREEK

At Herbert Road 36.7 600 1,500 2,000 3,100

GONZALES SLOUGH

Below football field 17.6 402 752 2302 2902

Below 7ili Street 17.5 452 1502 2502 3202

Below I st Street 17.4 652 2302 3102 4202

Below confluence with .· 17.4 160 300 360 430 East Branch Gonz(lles Slough

Below Monterey Vineyard 15.1 1203 1654 1654 1654

Culvert Above Monterey Vineyard 15.1 1203 2503 4003 6903

Culvert

HARPER CREEK

At San Benancio Gulch 2.2 1 50 143 202 390

1Reduction in flow values due to overbank storage in tidal flats 2Flow values reduced due to channel and overbank storage 3Flow values reduced due to upstream diversions 4Flow values reduced due to capacity restriction

BASE FLOOD

FLOODING SOURCE FLOODWAY WATER-SURFACE ELEVATION

(FEET NAVD)

SECTION MEAN

CROSS SECTION DISTANCE WIDTH AREA I ·· VELOCITY

REGULATORY . WITHOUT WITH

INCREASE (FEET) (SQUARE (FEET PER .. FLOODWAY FLOODWAY

FEET) SECOND)

East Branch Gonzales Slough .

A 4981 25 70 2.8 144.9 144.9 144.9 0.0 B 8591 30 50 3.9 147.4 147.4 147.4 0 .0

El Taro Creek A 3,008" 99 447 4.5 63.8 63.8 63.9 0.1 B 4,898" 78 298 6.7 78.1 78.1 78.1 ·. 0.0 c 6,528' 91 420 4.8 94.0 94.0 94.1 0 .1 D 8,208' 106 463 4.3 108.4 108.4 ·108.4 0.0 E 9,768" 91 421 4.8 120.4 120.4 120.4 0.0 F 11 ,438" 101 359 5.6 129.7 129.7 130.2 ·. 0.5 G 13,318' 59 228 8.8 149.4 149.4 149.4 0 .0 H 14,968' 72 389 5.1

164.3 164.3 . 164.4 0.1

I 17,058" 61 436 4.6 178.3 178.3 179.0 0.7 J 18,988L 67 442 4.5 190.9 190.9 191.9 1.0 K 2Q,888L 53 267 7.1 206.0 206.0 206.0 0.0 L 22,205' 185 476 4.5 226.2 226.2 226.3 0.0 M 22,674" 148 506 4.3 231.3 231.3 231.3 0 .0 N 22,906' 144 450 4.8 234.7 234.7 234.7 0.0

1Feet above confluence with Gonzales Slough 2Feet above confluence with Salinas River ·

~ FEDERAL EMERGENCY MANAGEMENT AG.ENCY

)> FLOODWAYDATA m r MONTEREY COUNTY, CA m . AND INCORPORATED AREAS ~ EAST BRANCH GONZALES SLOUGH- EL TORO CREEK w co "' 0 f--tt!

z

260 E±-" II p: -Hl+ ++ ~-'- -j- T

J H- - ., _ ~::r j=__-- ::_

~--~1 . + J '+ + _ -l - __ - + _ 1- + .: ... ,.. J __ ~ - -~ --- ~~ !- _-- ~~ 1--; L · ~- : :+ f+ • ±:1± ' . '

. ~- . ~-"-·- ~ -' . , . " ' C . . - Hi i"" . . .' . + ' 'I ' + , , " +t . , · + ~ rr , m -- - · + • ' H , ++ 26o

250 l i I - - + I+ : J::!- - : : r~ -;::+.::::: - _rrf_~-- - ; : -- " 'T- p 8} 'cc - -±t- _l_+ - 1-- ., . : . 'W.D H

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240 11 ~ , c--h .'1+ , : ' :j'' t+ - H -~u --~ c+-1 ' EB ~- I± Ifftill±:ti±H++t+ , tr j]: $ ++ -I I j_--ft1~ i --=~f;_JjtUii~tft+ _ : ~a= 230 "ft' 'i tir ' 1i:f~ · ~:1. ~Lm i±i±t ~ J r---t + 1~ ~ ,-1 -- - ___ _ __)__. I , t= ~~Jm 220 R=}~ fff-~ -ffi-Eflmj~ H~f r~

1-

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,_ I

ITTI-i::t.::: rrnp,:=

II ·--"-·

+tll l

1- -"-' "'1 '

T

-'l ·-r+ !,.

i 1--'- ,.

:K-

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-'· t

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' i

IIi

-l h=

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I-;.

II

1-i-

_L_ mlllW I

200 ==rr• --l=f-~, T-,-·1 -[ g

190. t h T rT .n I+ : -·· i . l

180 __ _

F

19500 20000 20500 21000 21500

L. .... ,. +-;-

IT·-

E 22000 22500 rl j:::rr:tttt::l

• 11-i-l- 1-f-1 l ,_ l=l++I++=I++++!+l-~ I I++ H- 1- 1-1 11 11 1;

23000

STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALINAS RIVER

:liU-I:BlE w

LEGEND

0.2% ANNUAL CHANCE FLOOO

1% ANNUAL CHANCE FLOOD

2% ANNUAL CHANCE FLOOD

10% ANNUAL CHANCE FLOOD

STREAM BED

CROSS SECTION LOCATION

Cl) w -1 :::.::

u:: L.U

L.U

0 ex:

0::

u c... 0 ex:

Cl 0 0 f--

0 ...J L.U l u::

u L.U (.!J <t f-- o:::x:

2 UIZl L.U ~<(

::2: >- LU

~ I-~ <t 2 Cl 2 :=l LU

<t 0 ~ ::2: u a:

>- >- 0...

u w a: as a: s (.!J w 2 ex: I- ;;

L.U 2 2 ::2: 0 <(

~::2!

<t 0:

L.U Q L.U u..

50P

62.6510

, 108.2464

, 315.2534 g 21 4 c:

.Q 1ii G) jjj 212

Fort_Ord Plan: Fort_ Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

~-------------------- Stream Reach --------------------~

'<t ll) ;:::; ,..._ tO ll) <D ,..._ N '<t 0 tO (') ,..._

;:::; ll) N ll) ~ 0) (')

:;:; '<t 0 0) 0) co 0 ll) <D co ll) N ~ co <D 0) ""': co co CD 0 N

<D cO ~ c:i I() ,...:

0 N .,.; ,...: -<i I()

N 0 M ll) ,..._ co ~ M ll) ,..._ ;:::; <D N N N N N

0 50 100 150 200 250 300 350

Main Channel Distance (ft)

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground g 216 c ,g Q) w 214

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom. Fort_Ord_Existing_with_bridge

RS = 315.2534

Flow: Fort_Ord_Fiow

-----~+~- ---~)'(~--M-----.05 '< .035 I Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

I neff

• Bank Sta

210~~~~~~~~rr~~.,~~~~,.~~~ g 218 c:

,g

216 Q) w

0 20 40 60 80 100 120 140

Station (f!)

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 257.6611

I--.05 ----J~- .035 + .05 ---)!~

0 20 40 60

Station (ft)

80 100 120

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta g 218 c:

.g Q) w 216 g 218 c

.Q

Q) w 216

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bndge

RS = 274.0892

Flow: Fort_Ord_Fiow u____ _ __ _,)!~(- --"')~~~(--- I ,... .o5 I .o35 .os )

0 20 60 80 100

Station (ft)

120 140

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 233.8557

1---.o5 --____,,"'l<~ .o3s + .os---'1

0 20 40 60 80 100

Station (ft)

120 140 160

Legend

WS FEMA 100-Year

WS FEMA 10-Year

• Bank Sta g c 220

Cll 218 iii g c 220 .Q iii Cll 218 iii

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow. Fort_Ord_Fiow

RS = 224.4612

.o54-- .035 -,*1<<---- . 05---~)1 Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

50 100 150 200 250 300

Station (ft)

Fort_Ord Plan: Fort_ Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 212.8026 Culv

-~)!~< - .035 ---'»)1~(---.05 ---.)1)1

50 100 150

Station (ft}

200 250 300

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta c 220 .Q

~ 218 iii

Fort_Ord Plan: Fort_ Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 212.8026 Culv

.05 4-- .035 + .05 )I Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

2 10~~~~~~~~~~~~~rT~~ .. ~~~ c 220 .Q

~ 218 iii

0 50 100 150 200 250 300

Station (ft)

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow. Fort_Ord_Fiow

RS = 201.4855

.05 -~)!~(- .035 ---'»)1~(---.05 ---~)1 Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

210~~~~~~ro~~~rr~~~~~.-~~~ 0 50 100 150

Station (ft)

200 250 300 g c:

0 ,..

Q) iii g Q) iii

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 187.9316

l<-.o5--*+E-- .035 -+---.05--~)1 220i Legend

208+-~-r~-r-~~-r---.-~~-.~---.~.-,-~ 0 20 40 60 80 100 120 140 160

Station (ft)

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 150.8931

l I >I< ----:.ll r--.05 - *E-- .035 I .05 ) 222 I

0 20 40 60

Station (ft)

80 100 120

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta I g c:

.Q iii s c:

.Q iii

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 175.6977

222J~k---.o5 .035 + .o5__, .------,-------,-----.

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

208~~~~~~.-~~-r~~~~~ro~~TO

20 40 60 80 100 120

Station (ft)

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow. Fort_Ord_Fiow

RS = 131.8035

-~)UI<- .o35 -~:K---- .o5 ----)!)1

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

208~~~-r~-.~~~,-~~~~--~-.~,-~

0 20 40 60

80 100 120 c 216 w

€ 220 c

.Q <0 S! 215 w

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS = 108.2464 + .035 + . OS---~

20 40 60 80 100 120

Station (ft)

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_Ord_Existing_with_bridge Flow: Fort_Ord_Fiow

RS=14.1154

.os + .o3s + .os-4

20 40 60 80

Station (ft)

Legend

WS FEMA 100-Year

WS FEMA 10-Year

Ground

• Bank Sta

Fort_Ord Plan: Fort_Ord_Existing_with_Bridge 3/9/2010 Geom: Fort_ Ord_Existing_ with_bridge Flow: Fort_ Ord_Fiow

RS = 62.6510

~.05-~>~1<--.035

+ .os-4

205+-~~~rT~~-.~~-r.-~-~~~~ro 0 20 40 60 80 100

Station (ft)

Legend

WS FEMA 100-Year

WS FEMA 10-Year

HEC-RAS Plan· Existing bri River· Stream Reach· Reach

Reach River Sta Profile Q Total MinCh El W .S. Elev CritW.S. E.G. Elev E.G. Slope VeiChnl Flow Area Top Width Froude# Chi

(cfs) (ft) (ft) (ft) (ft) (ftlfl) (ft/s) (sq ft) (ft)

Reach 315.2534 18-inch depth 50.00 211 .28 212.61 212.42 212.82 0.010370 3.74 13.36 16.28 0.73

Reach 315.2534 FEMA2-Year 126.00 211 .28 213.33 213.06 213.66 0.009414 4.64 27.15 22.23 0.74

Reach 315.2534 FEMA 10-Year 356.00 211.28 214.54 214.18 215.06 0.008906 5.83 61 .04 34.04 0.77

Reach 315.2534 FEMA 50-Year 1033.00 211 .28 216.72 215.87 217.36 0.004376 6.63 188.58 98.51 0.61

Reach 315.2534 FEMA 100-Year 1642.00 211 .28 217.97 217.06 218.58 0.003187 6.86 325.47 118.35 0.54

Reach 315.2534 FEMA 500-Year 2844.00 211.28 219.77 218.25 220.40 0.002430 7.37 556.44 136.29 0.50

Reach 315.2534 FEMA 25-Year 800.00 211 .28 216.03 215.37 216.72 0.005835 6.67 125.89 71 .23 0.68

Reaeh 274.0892 18-lnch depth 50.00 210.89 212.12 212.37 0.011497 4.00 12.51 14.85 0.77

Reach 274.0892 FEMA 2-Year 126.00 210.89 212.83 213.24 0.010961 5.1 1 24.65 19.41 0.80

Reach 274.0892 FEMA 10-Year 356.00 210.89 214.24 214.75 0.006590 5.78 66.90 43.44 0.68

Reach 274.0892 FEMA 50-Year 1033.00 210.89 216.68 217.17 0.002902 6.28 236.27 95.25 0.51

Reach 274.0892 FEMA 100-Year 1642.00 210.89 217.91 218.43 0.002501 6.81 359.26 104.23 0.49

Reach 274.0892 FEMA 500-Year 2844.00 210.89 219.66 220.30 0.002360 7.87 552.83 116.98 0.50

Reach 274.0892 FEMA 25-Year 800.00 210.89 215.96 216.48 0.003592 6.25 172.58 80.72 0.55

Reach 257.6611 18-inch depth 50.00 210.78 211.93 212.18 0.012006 4.03 12.40 14.99 0.78

Reach 257.6611 FEMA 2-Year 126.00 210.78 212.67 213.06 0.010280 4.97 25.35 19.83 0.77

Reach 257.6611 FEMA 10-Year 356.00 210.78 214.17 214.63 0.005936 5.51 68.46 37.52 0.65

Reach 257.6611 FEMA 50-Year 1033.00 210.78 216.40 217.09 0.003953 7.10 186.30 85.91 0.59

Reach 257.6611 FEMA 100-Year 1642.00 210.78 217.60 218.35 0.003485 7.82 293.84 93.01 0.58

Reach 257.661 1 FEMA 500-Year 2844.00 210.78 219.31 220.22 0.0032.38 8.99 461 .05 101 .53 0.58

Reach 257.6611 FEMA 25-Year 800.00 210.78 215.77 216.40 0.004270 6.67 141.92 54.38 0.60

Reach 233.8557 18-inch depth 50.00 210.33 211 .74 211 .85 0.004722 2.71 18.48 20.32 0.50

Reach 233.8557 FEMA2-Year 126.00 210.33 212.60 212.76 0.003756 3.26 38.60 26.86 0.48

Reach 233.8557 FEMA 10-Year 356.00 210.3·3 214.16 214.42 0.002640 4.10 89.35 37.93 0.44

Reach 233.8557 FEMA 50-Year 1033.00 210.33 216.47 216.90 0.002184 5.49 233.33 85.45 0.44

Reach 233.8557 FEMA 100-Year 1642.00 210.33 217.65 218.18 0.002217 6.41 346.07 106.11 0.46

Reach 233.8557 FEMA 500-Year 2844.00 210.33 219.39 220.04 0.002136 7.47 556.16 133.29 0.48

Reach 233.8557 FEMA 25-Year 800.00 210.33 215.82 216.20 0.002338 5.14 182.56 71 .57 0.45

Reach 224.4612 18-lnch depth 50.00 210.34 211 .37 211 .36 211.75 0.020963 4.93 10.14 13.85 1.02

Reach 224.4612 FEMA2-Year 126.00 210.34 212.58 211 .98 212.72 0.003720 3.03 41 .52 32.04 0.47

Reach 224.46 12 FEMA 10-Year 356.00 210.34 214.18 212.85 214.37 0.002211 3.50 101.58 42.38 0.40

Reach 2.24.4612 FEMA 50-Year 1033.00 210.34 216.56 214.44 216.83 0.001657 4.37 282.10 119.64 0.38

Reach 224.4612 FEMA 100-Year 1642.00 210.34 217.79 215.66 218.10 0.001429 4.83 435.32 126.86 0.37

Reach 2.24.4612 FEMA 500-Year 2844.00 210.34 219.55 217.05 219.95 0.001341 5.65 661 .62 131.28 0.37

Reach 224.4612 FEMA 25-Year 800.00 210.34 215.88 213.99 216.15 0.001982 4.24 207.33 98.73 0.40

HEC-RAS Plan· Existing bri River Stream Reach· Reach (Continued)

Reach River Sta Profile Q Total Min Ch El W.S. Elev CritW.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude#Chl

(cfs) (ft) (ft) (ft) (ft) (ftlft) (fVs) (sq ft) (ft)

Reach 212.8026 Culvert

Reach 201 .4855 18-inch depth 50.00 210.09 211.61 211 .75 0.006666 2.98 16.80 20.69 0.58

Reach 201.4855 FEMA2-Year 126.00 210.09 212.58 212.72 0.003245 2.93 43.03 31 .55 0.44

Reach 201.4855 FEMA 10-Year 356.00 210.09 214.18 214.37 0.002199 3.48 102.16 42.91 0.40

Reach 201 .4855 FEMA 50-Year 1033.00 210.09 216.49 216.81 0.001954 4.59 243.53 94.47 0.41

Reach 201.4855 FEMA 100-Year 1642.00 210.09 217.66 218.06 0.001826 5.28 366.64 110.87 0.41

Reach 201.4855 FEMA 500-Year 2844.00 210.09 219.34 219.87 0.001785 6.30 561.83 120 71 0.43

Reach 201 .4855 FEMA 25-Year 800.00 210.09 215.84 216.13 0.002153 4.36 187.03 78.18 0.42

Reach 187.9316 18-inch depth 50.00 209.74 211 .06 211 .06 211 .52 0.020170 5.43 9.21 10.20 1.01

Reach 187.9316 FEMA 2-Year 126.00 209.74 211 .86 211 .86 212.54 0.017963 6.62 19.04 14.25 1.01

Reach 187.9316 FEMA 10-Year 356.00 209.74 213.27 213.27 214.21 0.015880 7.76 45.88 24.93 1.01

Reach 187.9316 FEMA 50-Year 1033.00 209.74 215.23 215.23 216.63 0.01 1843 9.62 114.47 45.10 0.95

Reach 187.9316 FEMA 100-Year 1642.00 209.74 216.54 216.53 217.90 0.007925 9.87 209.56 8884 0.83

Reach 187.9316 FEMA 500-Year 2844.00 209.74 218.73 219.77 0.004149 9.33 440.46 119.60 0.64

Reach 187.9316 FEMA 25-Year 800.00 209.74 214.68 214.68 215.96 0.012617 9.10 91 .32 39.42 0.96

Reach 175.6977 18-inch depth 50.00 208.82 210.37 210.29 210.73 0.015923 4.79 10.43 11 .87 0.90

Reach 175.6977 FEMA2-Year 126.00 208.82 211 .28 211.73 0.011213 5.41 23.28 16.81 0.81

Reach 175.6977 FEMA 10-Year 356.00 208.82 212.56 212.38 213.37 0.010591 7.30 51.48 27.57 0.85

Reach 175.6977 FEMA 50-Year 1033.00 208.82 215.17 214.40 216.04 0.005288 7.95 163.86 71 .85 0.67

Reach 175.6977 FEMA 100-Year 1642.00 208.82 216.88 217.60 0.003211 7.73 302.99 89.29 0.55

Reach 175.6977 FEMA 500-Year 2844.00 208.82 218.78 219.64 0.002957 8.90 484.27 106.48 0.56

Reach 175.6977 FEMA25-Year 800.00 208.82 214.34 213.86 215.26 0.007178 8.03 114.34 43.35 0.76

Reach 150.8931 18-inch depth 50.00 208.47 209.96 209.87 210.34 0.015025 4.91 10.17 10.48 0.88

Reach 150.8931 FEMA 2-Year 126.00 208.47 210.69 210.69 211 .36 0.017898 6.57 19.18 14.56 1.01

Reach 150.8931 FEMA 10-Year 356.00 208.47 212.03 212.03 213.04 0.014896 8.09 44.51 23.25 0.99

Reach 150.8931 FEMA 50-Year 1033.00 208.47 214.08 214.08 215.76 0.011549 10.61 105.54 36.02 0.97

Reach 150.8931 FEMA 100-Year 1642.00 208.47 215.71 215.71 217.39 0.007585 10.94 187.83 67.76 0.83

Reach 150.8931 FEMA 500-Year 2844.00 208.47 217.38 217.38 219.41 0.007116 12.70 314.17 83.92 0.84

Reach 150.8931 FEMA 25-Year 800.00 208.47 213.53 213.53 214.98 0.012098 9.76 86.70 32.72 0.96

Reach 131 .8035 18-inch depth 50.00 208.59 209.62 209.62 210.01 0.020320 4.98 10.04 13.14 1.00

Reach 131 .8035 FEMA2-Year 126.00 208.59 210.30 210.30 210.89 0.017936 6.13 20.54 17.81 1.01

Reach 131 .8035 FEMA 10-Year 356.00 208.59 211 .49 211 .49 212.42 0.014362 7.76 47.25 27.23 0.98

Reach 131.8035 FEMA 50-Year 1033.00 208.59 213.88 214.98 0.007205 8.68 132.44 43.63 0.78

HEC-RAS Plan· Existing bri River· Stream Reach· Reach (Continued)

Reach River Sta Profile Q Total MinCh El W .S. Elev CritW.S. E.G. Elev E.G. Slope VeiChnl Flow Area Top Width Froude#Chl

(cfs) (ft) (ft) (ft) (ft) (ftlft) (fUs) (sq ft) (ft)

Reach 131.8035 FEMA 100-Year 1642.00 208.59 215.39 216.63 0.005447 9.42 212.59 66.88 0.72

Reach 131.8035 FEMA 500-Year 2844.00 208.59 217.81 219.02 0.003615 9.83 401 .03 89.61 0.62

Reach 131.8035 FEMA 25-Year 800.00 208.59 213.19 214.22 0.008620 8.34 104.07 39.04 0.83

Reach 108.2464 18-inch depth 50.00 207.42 209.10 209.28 0.007315 3.47 14.41 14.82 0.62

Reach 108.2464 FEMA 2-Year 126.00 207.42 210.08 210.32 0.005330 3.92 32.15 21.68 0.57

Reach 108.2464 FEMA 10-Year 356.00 207.42 211 .64 211 .99 0.004224 4.71 75.80 34.19 0.54

Reach 108.2464 FEMA 50-Year 1033 00 207.42 214.11 214.66 0.003018 6.06 183.16 50.67 0.51

Reach 108.~404 FEMA 100-Year 164~.00 207.4~ 215.65 216.34 0.002604 6.88 268.44 60.89 0.50

Reach 108.2464 FEMA 500-Year 2844.00 207.42 217.92 I 218.83 0.002345 8.11 425.49 77.42 0.50

Reach 108.2464 FEMA 25-Year 800.00 207.42 213.40 213.89 0.003365 5.71 147.96 47.32 0.52

Reach 62.6510 18-inch depth 50.00 206.90 208.81 208.29 209.00 0.005492 3.47 14.40 11 .53 0.55

Reach 62.6510 FEMA 2-Year 126.00 206.90 209.64 209.15 210.01 0.007830 4.90 25.73 16.08 0.68

Reach 62.6510 FEMA 10-Year 35600 206.90 210.75 210.61 211 .62 0.013034 7.49 47.55 23.19 0.92

Reach 62.6510 FEMA 50-Year 1033.00 206.90 212.67 212.67 214.31 0.011789 10.35 103.63 35.52 0.96

Reach 62.6510 FEMA 100-Year 1642.00 206.90 213.98 213.98 216.00 0.009872 11 .66 155.97 44.25 0.93

Reach 62.6510 FEMA 500-Year 2844.00 206.90 215.95 215.95 218.49 0.008353 13.44 256.20 57.28 0.90

Reach 62.6510 FEMA 25-Year 800.00 206.90 212.08 212.08 213.52 0.013069 9.67 83.84 31 .63 0.98

Reach 14.1154 18-inch depth 50.00 207.02 208.30 208.17 208.59 0.013002 4.33 11 .53 13.18 0.82

Reach 14.1154 FEMA 2-Year 126.00 207.02 209.06 208.88 209.52 0.013004 5.47 23.03 18.45 0.86

Reach 14.1154 FEMA 10-Year 356.00 207.02 210.18 210.10 210.97 0.013012 7.16 50.70 29.57 0.93

Reach 14.1154 FEMA 50-Year 1033.00 207.02 211 .92 211 .92 213.48 0.010963 10.24 110.92 39.28 0.95

Reach 14.1154 FEMA 100-Year 1642.00 207.02 213.13 213.13 215.10 0.009787 11 .72 162.00 45.60 0.94

Reach 14.1154 FEMA 500-Year 2844.00 207.02 215.00 215.00 217.56 0.008628 13.71 256.13 54.92 0.94

Reach 14.1154 FEMA 25-Year 800.00 207.02 211 .36 211 .36 212.74 0.012028 9.57 89.57 36.14 0.97

\ 4.1154

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Fort_Ord Plan: Fort_Ord_Proposed_Low_ Water_ Crossing_Fin 2/25/2010 Geom: Fort_Ord_Proposed_Low_Water_Crossing_Fin Flow: Fort_Ord_Fiow

~-------------------- Stream Reach --------------------~

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0 50 100 150 200 250 300 350

Main Channel Distance (ft)

Legend

WS FEMA 100-Year

WS FEMA 25-Year

WS FEMA 10-Year

WS 18-inch depth

HEC-RAS Plan· LWC-Final River· Stream Reach· Reach

Reach River Sta Profile Q Total MinCh El W.S. Elev CritW.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude#Chl

(cfs) (ft) (ft) (ft) (ft) (ftlft) (fils) (SQ ft) (ft)

Reach 3152534 18-inch depth 50.00 211.28 212.61 212.82 0.010379 3.74 13.35 16.28 0.73 Reach 315.2534 FEMA 10-Year 356.00 211.28 214.57 215.08 0008502 5.73 62.12 34.35 0.75

Reach 315.2534 FEMA 50-Year 1033.00 211 .28 216.57 217.34 0.005389 7.15 158.53 93.61 0.67

Reach 315.2534 FEMA 100-Year 1642.00 211 .28 217.76 218.56 0.004211 7.66 282.31 115.96 0.62

Reach 315.2534 FEMA 25-Year 800.00 211 .28 215.99 216.70 0.006120 6.77 123.62 69.41 0.69

Reach 274.0892 18-inch depth 50.00 210.89 212.13 212.37 0.011403 3.99 12.55 14.86 0.76

Reach 274.0892 FEMA 10-Year 356.00 210.89 21 4.33 214.76 0.005969 5.29 71.07 45.38 0.64

Reach 274.0892 FEMA 50-Year 1033.00 210.89 216.61 217.10 0.002959 6.09 230.09 94.78, 0.51

Reach 274.0892 FEMA 100-Year 1642.00 210.89 217.81 218.34 0.002591 6.69 348.35 103.47 0.50

Reach 274.0892 FEMA 25-Year 800.00 210.89 215.96 216.44 0.003471 5.92 172.45 80.69 0.54

Reach 257.6611 18-inch depth 50.00 210.78 211 .94 212.18 0.0114 11 3.96 12.62 15.08 0.76

Reach 257.6611 FEMA 10-Year 356.00 210.78 214.27 214.65 0.005410 4.95 72.50 38.64 0.61

Reach 257.6611 FEMA 50-Year 1033.00 210.78 216.39 217.02 0.003729 6.60 185.78 85.87 0.57

Reach 257.6611 FEMA 100-Year 1642.00 210.78 217.52 218.27 0.003442 7.44 286.96 92.57 0.57

Reach 257.6611 FEMA 25-Year 800.00 210.78 215.82 216.37 0.003856 6.09 144.93 55.28 0.57

Reach 233.8557 18-inch depth 50.00 210.33 211 .78 211 .89 0.004131 2.58 19.36 2D.63 0.47

Reach 233.8557 FEMA 10-Year 356.00 210.33 214.23 214.46 0.002707 3.86 92.11 38.67 0.44

Reach 233.8557 FEMA 50-Year 1033.00 210.33 216.45 216.84 0.002171 5.15 231.51 84.79 0.44

Reach 233.8557 FEMA 100-Year 1642.00 210.33 217.58 218.09 0.002215 6.07 338.82 104.90 0.46

Reach 233.8557 FEMA 25-Year 800.00 210.33 215.86 216.20 0.002258 4.75 185.22 72.18 0.43

Reach 224.4612 18-inch depth 50.00 210.34 211 .65 211 .82 0.010452 3.36 14.87 21.46 0.71

Reach 224.4612 FEMA 10-Year 356.00 210.34 214.24 214.42 0.002060 3.42 104.12…