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Floodplain Modification Submittal to the Town of Vail November 15, 2010
Ever Vail Flood Plain Modification Permit 2 Table of Contents I. Directory ....................................................................................................................3
II. Introduction...............................................................................................................4 III. Floodplain Modification Application Submittal Requirements.......
...........................6 IV. Floodplain Modification Review Criteria ...................................................................7 V. Adjacent Addresses ...................................
..............................................................12 VI. Attachments ............................................................................................................14
Ever Vail Flood Plain Modification Permit 3 I. Directory Vail Resorts Development Company 137 Benchmark Road Avon, CO 81620 (ph) 970‐754‐2544 Tmiller1@vailresorts.com Mauriello Planning
Group PO Box 1127 Avon, CO 81620 (ph) 970.748.0920 dominic@mpgvail.com AMEC Earth & Environmental 1002 Walnut, Suite 200 Boulder, CO 80302 (ph) 303.443.7839 Alpine Engineering, Inc.
P.O. Box 97 Edwards, CO 81632 (ph) 970.926.3373 Paladino and Company (ph) 206.522.7600 www.paladinoandco.com Kimley‐Horn and Associates, Inc 950 Seventeenth Street Suite 1050 Denver,
CO 80202 (ph) 303.228.2300 LandWorks Design, Inc. 3457 Ringsby Court Suite 110 Denver, CO 80202 (ph) 303.433.4257 Peak Land Consultants, Inc. 1000 Lions Ridge Loop Vail, CO 81657 (ph)
970.476.8644 CALLISON 1420 Fifth Avenue #2400 Seattle, WA 98101‐2343 (ph) 206.623.4646
Ever Vail Flood Plain Modification Permit 4 II. Introduction As part of the overall Ever Vail project, the South Frontage Road will be relocated to the north immediately adjacent and
parallel to the eastbound lanes of I‐70. This realignment will require the construction of a bridge across Red Sandstone Creek directly south of the I‐70 right‐of‐way. As a result, a
Town of Vail Floodplain Modification Permit is required for the work that is needed to complete the road relocation. The existing South Frontage Road crosses Red Sandstone Creek approximately
350 feet south of the proposed location for the new crossing as shown in Figure 1 (USGS Quadrangle: Vail West, Co, Sections 6 and 7 of Township 5S, Range 80W). The project area is shown
in Figure 1. Figure 1. Project Area for the New Frontage Road Bridge A floodplain modification is defined by the Vail Town Code as follows: A floodplain modification permit is a permit
to allow construction of improvements and/or modifications to the adopted floodplain for all other uses, improvements, or modifications to or within the floodplain that do not fall within
the guidelines of the floodplain use permit. However, no habitable structures or improvements shall be allowed to be constructed within the floodplain (12‐21‐11E.2.a.).
Ever Vail Flood Plain Modification Permit 5 Existing Conditions at Red Sandstone Creek and the I‐70 CMP:
Ever Vail Flood Plain Modification Permit 6 III. Floodplain Modification Application Submittal Requirements The Town Code requires the following submittal information for the review
of a floodplain modification permit. Requirement Comments Submitted (1) Elevation of the lowest floor (including basement and crawl space) of all new and substantially improved structures
within or adjacent to the floodplain. These elevations have been submitted with the overall Ever Vail submittal, and are also included in this submittal. YES (2) Description of the extent
to which any floodplain will be altered including why, when, how, and when it will be replaced back to its original configuration, and addressing each relevant factor in subsection E3
of this section. This information is included in the attached Hydraulic Analysis and each relevant factor from Section E3 is addressed in Section V of this submittal YES (3) Signature
of the owners of all property subject to an impact by the proposed improvement. The property impacted by this application is currently owned by Vail Resorts. In the future, it will be
owned by CDOT. CDOT and Vail Resorts are aware of this application. YES (4) A site plan drawn to an engineering scale showing the location, dimensions, and elevations of the proposed
landscape/grade alterations, existing and proposed structures, relevant landscape/topographic features, and the location of the foregoing in relation to the 100‐ year floodplain. The
floodplain line shall be provided on a plan certified by a licensed professional engineer or land surveyor. The site plan has been completed by Landworks Design and Alpine Engineering
and AMEC Earth & Environmental. YES (5) Detailed topographic cross sections provided by a licensed professional surveyor of the area proposed to be altered, showing existing and proposed
conditions. Peak Land Consultants has provided this information. The topographic survey and sections are included in this submittal. YES (6) Copy of all other necessary approved permits
(i.e., building permit, public way permit, ACOE permit, dewatering permit, DOW permit, CDHPE permit). Required permits will be submitted as they are approved. A 404 permit application
is being submitted to the ACOE in 2011. Under the Colorado Discharge Permit System the following will be submitted: Stormwater Construction Permit ; Construction Dewatering Wastewater
discharge Permit. No permits are required by the Colorado Division of Wildlife but consultation with the DOW has occurred in regards to potential stream habitat improvements for Red
Sandstone Creek. NA (7) An engineered floodplain analysis of the impacts to the floodplain prepared by a qualified licensed professional engineer. A Hydraulic Analysis is included in
this submittal. YES (8) Copy of submitted application for a conditional FIRM and floodway revision through FEMA, if applicable. A CLMOR will be submitted in 2011. A Letter of Map Revision
(LOMR) will be submitted to FEMA within 6 months of the project completion. NA (9) Environmental impact report, per chapter 12 of this title. An Environmental Impact Report is being
submitted as part of this submittal package. YES (10) Any additional information deemed necessary by the floodplain administrator. NA
Ever Vail Flood Plain Modification Permit 7 IV. Floodplain Modification Review Criteria Chapter 21, Hazard Regulations, Vail Town Code provides the requirements and review criteria for
a flood plain modification permit. The purpose of the flood hazard regulations is as follows: To promote public health, safety and general welfare and to minimize public and private
losses due to flood conditions in specific areas by provisions designed to: 1. Protect human life and health; 2. Minimize expenditure of public money for costly flood control projects;
3. Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public; 4. Minimize prolonged business interruptions;
5. Minimize damage to public facilities and utilities such as water and gas mains, electric, telephone and sewer lines, streets and bridges located in floodplains; 6. Help maintain a
stable tax base by providing for the sound use and development of flood prone areas in such a manner as to minimize future flood blight areas; 7. Ensure that potential buyers are notified
that property is in a flood area; 8. Ensure that those who occupy the floodplain assume the responsibility for their actions; 9. Protect the natural areas required to convey flood flows
and retain flow characteristics; and 10. Obtain and maintain the benefits to the community of participating in the national flood insurance program. All floodplain modification permits
are reviewed by the Floodplain administrator and the Planning and Environmental Commission subject to the following criteria: A. The effects upon the efficiency or capacity of the floodway.
Our Analysis: There is no designated floodway for Red Sandstone Creek. The impacts to the floodplain boundary were evaluated using HEC‐RAS and are discussed in the attached engineering
hydraulic analysis. B. The effects upon persons and personal property upstream, downstream and in the immediate vicinity. Our Analysis: There will be no adverse effect upon persons or
personal property upstream, downstream or in the immediate vicinity. All new construction will be outside of the newly proposed floodplain. The water surface elevations or velocities
do not increase downstream or upstream of the project area and therefore will not adversely impact persons or properties outside of the project area. C. The effects upon the 100‐year
flood profile and channel stability. Our Analysis: The impacts to the floodplain boundary were evaluated using HEC‐RAS. HEC‐RAS results show less than a foot increase in water surface
elevation profiles downstream of the project area. The floodplain decreases in width downstream of the new South Frontage Road Bridge, and shortly downstream returns to its existing
configuration. The constriction of the floodplain is due to the channelization of flow through the arched culvert. FHWA design specifications were used to create the design details to
protect the bridge and prevent scour of the channel during high flow events. A riprap energy dissipation basin has has been designed to force a hydraulic jump in order to dissipate energy
from flow out of the I‐70 CMP. The channel bed will
Ever Vail Flood Plain Modification Permit 8 be lined with grouted riprap with a median diameter of 12 inches. A drop structure and scour pool will be placed just downstream of the bridge
to limit the downstream impact and limit further impacts to Red Sandstone Creek. The area to the west of the creek, just downstream of the bridge, will be graded to create a gradual
slope from the southern edge of the retaining wall down to the creek. The area to the east has a steep bank and will not be modified. The attached engineering hydraulic analysis describes
the impacts to the floodplain in depth and includes design drawings with channel design details. D. The effects upon any tributaries to the main stream, drainage ditches and any other
drainage facilities or systems. Our Analysis: This design will not impact any tributaries to the main stream, drainage ditches or any other drainage facilities. A storm drain will collect
water from the east side of the new South Frontage Road and discharge to Red Sandstone Creek just downstream of the new bridge. Storm water will go through a stormwater treatment system
(Vortechs Model 16000) before discharging to Red Sandstone Creek. The calculated discharge rate during a 100‐yr flow event is 24 cfs. E. The danger to life and property due to flooding
or erosion damage; Our Analysis: There will be no increase in the danger to life or property due to flooding or erosion damage associated with the proposed project. There are no structures
within the proposed floodplain. There should be little or no erosion around the bridge since the channel will be armored to prevent scour during the 500‐yr flood event. The downstream
channel will be armored with loose river cobble with a median diameter of 6 inches, which is the estimated median diameter of the existing river cobble in this reach. F. The susceptibility
of the proposed improvement and its contents to flood damage and the effect of such damage on the individual owner; Our Analysis: The channel below the bridge will be armored to protect
the foundation from scour during a 500‐yr flow event. The bridge footers will be protected from downstream erosion by a concrete cutoff wall that is located at the downstream end of
the bridge. Design drawings are included as an exhibit to the attached engineering hydraulic analysis G. The danger that materials may be swept onto other lands to the injury of others;
Our Analysis: The I‐70 CMP restricts much of the debris from the headwaters. There is some debris at the site that will be removed, but, for the most part, the amount of debris will
remain the same. In addition, there are no other landowners along Red Sandstone Creek. Therefore the probability of a downstream landowner being impacted by debris along Red Sandstone
Creek is unlikely. H. The compatibility of the proposed use with existing and anticipated development; Our Analysis: The land adjacent to Red Sandstone Creek Floodplain is currently
zoned Arterial Business District to the west and Lionshead Mixed Use – 2 to the east of the creek. The proposed zoning for the entire site is Lionshead Mixed Use – 2. The relocation
of the South Frontage Road consolidates the impacts to the creek (both existing and proposed) to one area, allowing for the remainder of the creek (downstream to Gore Creek) to be improved
and restored, and to create a community amenity. A complete analysis of the anticipated development of Ever Vail is included in this submittal package.
Ever Vail Flood Plain Modification Permit 9 I. The safety of access to the property in times of flood for ordinary and emergency vehicles; Our Analysis: None of these bridges will be
flooded. Emergency Vehicles can access the east side of property utilizing the South Frontage Road and Forest Road. Emergency Vehicles can access the west side of property utilizing
the South Frontage Road. J. The costs of providing governmental services during and after flood conditions including maintenance and repair of streets and bridges, and public utilities
and facilities such as sewer, gas, electrical and water systems; Our Analysis: These costs will remain the same. There are no new utilities located within the existing or proposed floodplain
boundary. All new utilities will be located above the floodplain and will be accessed via the new South Frontage Road Bridge. K. The expected heights, velocity, duration, rate of rise
and sediment transport of the floodwaters and the effects of wave action, if applicable, expected expected at the site; Our Analysis: The impacts to the floodplain boundary were evaluated
using HEC‐RAS. HEC‐RAS results show less than a foot increase in water surface elevation profiles downstream of the project area. The floodplain boundary decreases in width a short distance
downstream of the new South Frontage Road Bridge and shortly downstream returns to its existing configuration. The attached Engineering Hydraulic Analysis describes the impacts to the
floodplain in depth. L. The effect the proposed changes will have any adverse environmental effect on the watercourse including, without limitation, erosion of stream banks and stream
side trees and vegetation and wildlife habitat; Our Analysis: The realignment of Red Sandstone Creek to accommodate the new South Frontage Road Bridge will have a small environmental
effect on the watercourse under the new bridge. The Red Sandstone Creek stream ecosystem in the vicinity of the Site has been diminished due to channelized stream conditions and steep
banks caused by fill material from neighboring parcels and the I‐70 CMP. The stream bottom consists of boulders and cobbles and provides limited habitat for several species of fish.
According to the CDOW, the following species of fish could be found in Red Sandstone Creek below the I‐70 culvert: brown trout, rainbow trout, brook trout, cutthroat trout, and sculpin
(Andree, pers. comm.). However, resting and spawning areas for fish are extremely limited in this section of Red Sandstone Creek, especially during spring runoff and critical low flow
periods in the late summer, fall, and winter. There are wetlands adjacent to Red Sandstone Creek; however, infringement from development has degraded riparian habitat, which is limited
to a narrow band along the stream banks. All wetland impacts will be mitigated as required by the Army Corps of Engineers. A wetland mitigation plan and a 404 Permitting will be completed
in 2011. The proposed floodplain will not cause an increase in erosion of stream banks. Many of the trees in the vicinity will be preserved. Some trees have been designated for removal
due to their deteriorating health, and one tree will be removed to accommodate the new channel alignment. The vegetation that is impacted during construction will be revegetated as defined
in the Landscaping plans created by Landworks Design.
Ever Vail Flood Plain Modification Permit 10 M. The necessity to the facility of a waterfront location, where applicable; Our Analysis: A variety of alternatives were evaluated to select
an optimal Creek alignment and set of structures that would minimize floodplain impacts downstream of the proposed South Frontage Road Bridge crossing Red Sandstone Creek. In order to
span the existing floodplain, a 120’ spanned bridge would be required to traverse the floodplain. This alternative was not chosen due to the associated cost and aesthetic considerations.
Various bridge spans were evaluated to determine the most appropriate size and style available that will appropriately convey and manage flow through the new structure. A single span
bridge with 42‐ foot clear opening was selected as the most appropriate, cost effective and aesthetic alternative. The span of the proposed bridge was developed using HEC‐RAS to model
various stream geometries and bridge span options to identify a bridge span length that would not not significantly impact water surface elevations of the Creek downstream. Once this
span length was determined the remaining design characteristics were determined through an iterative process using Federal Highway Administration (FHWA) standards and HEC RAS modeling.
The primary design parameters were based on the following objectives: maintain channel stability by armoring the new channel under the bridge to prevent scour during a 500‐yr flood event,
include channel geometry that is similar to the existing stream geometry, and provide sufficient channel conveyance capacity to minimize changes to the existing 100‐year water surface
elevation. N. The availability of alternative locations, not subject to flooding or erosion damage, for the proposed use; Our Analysis: There is no alternative location because of the
necessity to cross Red Sandstone Creek. O. The relationship of the proposed use to the comprehensive plan for that area. Our Analysis: The relocated South Frontage Road is identified
as a possibility in the Lionshead Redevelopment Master Plan for the West Lionshead area. The existing alignment includes a small radius curve in the road, creating conditions that are
unsafe in that area. The Lionshead Redevelopment Master Plan contemplated a South Frontage Road alignment which parallels I‐70, but returns to the original location at Red Sandstone
Creek. This alignment was not acceptable to CDOT, as it maintains an unsafe bend in the road. CDOT has indicated that the only acceptable alignment parallels I‐70 for the entire distance
of the West Lionshead area, joining back up to the existing alignment just west of the existing Glen Lyon Office Building. In addition, the alignment contemplated by the Lionshead Redevelopment
Master Plan would have required significant disturbance to Red Sandstone Creek, because the proposed bridge would have run parallel to the creek for a distance. In conclusion, the alignment
of the South Frontage Road and the floodplain modification required are in compliance with the Lionshead Redevelopment Master Plan and associated Transportation Master Plans for the
traffic network in the Town of Vail. The following findings shall be made before granting of a floodplain permit: (1) That the proposed use or modification adequately addresses the findings
in subsection E3a of this section, as determined by the floodplain administrator, unless the applicant can demonstrate that one or more of the standards is not applicable, or that a
practical solution consistent with the public interest has been achieved;
Ever Vail Flood Plain Modification Permit 11 (2) That the proposed use or modification is consistent with the adopted goals, objectives and policies outlined in the Vail comprehensive
plan and compatible with the development objectives of the town; and (3) That the proposed use or modification is compatible with and suitable to adjacent uses and appropriate for the
surrounding areas; and (4) That the proposed use or modification promotes the health, safety, morals, and general welfare of the town and promotes the coordinated and harmonious development
of the town in a manner that conserves and enhances its natural environment and its established character as a resort and residential community of the highest quality.
Ever Vail Flood Plain Modification Permit 12 V. Adjacent Addresses 210312109003 GLEN LYON OFFICE BUILDING C/O ANDREW D. NORRIS 1000 S FRONTAGE RD W STE 200 VAIL, CO 81657 210312100005
000934 FRONTAGE RD VAIL CORPORATION PO BOX 959 AVON, CO 81620‐0959 210312100004 001031 FRONTAGE RD SOHO DEVELOPMENT LLC 950 17TH ST STE 1600 DENVER, CO 80202 210312100002 000953 FRONTAGE
RD SOHO DEVELOPMENT LLC 950 17TH ST STE 1600 DENVER, CO 80202 210312124001 000923 FRONTAGE RD W VAIL CORP PO BOX 7 VAIL, CO 81658 210312109004 SUB:GLEN LYON SUBDIVISION LOT:39‐2 ROBERT
J. ROSEN 2005 QPRT NANCY ROSEN 2005 QPRT 1127 LAKE AVE GREENWICH, CT 06831 210312109005 ORRAS, IGNACIO 777 POST OAK BLVD 550 HOUSTON, TX 77056 210107216001 000846 FOREST RD EAGLE RIVER
WATER & SANITATION DIST 846 FOREST RD VAIL, CO 81657 210107200001 210312109002 210312100010 210107200001 210106302004 210107218002 210107218001 TOWN OF VAIL C/O FINANCE DEPT 75 S FRONTAGE
RD VAIL, CO 81657 210107217004 000825 FOREST RD GORE CREEK PLACE LLC PO BOX 7 VAIL, CO 81658 210107217002 000728 LIONSHEAD CIR VAIL CORP PO BOX 7 VAIL, CO 81658 000710 LIONSHEAD CIR
VAIL SPA CONDOMINIUM ASSOC 710 W LIONSHEAD CIR VAIL, CO 81657 DANN PETER ‐Registered Agent PO BOX 5480 AVON, CO 81620 001000 LIONS RIDGE LOOP VAIL RUN RESORT COMMUNITY 1000 LIONS RIDGE
LOOP VAIL, CO 81657 Vail Run Resort Community Assoc Inc William I Fleischer ‐Registered Agent 1000 LIONSRIDGE LOOP VAIL, CO 81657 210107217002 RCR Vail LLC 390 INTERLOCKEN CRESCENT STE
1000 BROOMFIELD , CO 80021 Gore Creek Place LLC 390 Interlocken Crescent, Broomfield, CO 80021 210107222004 JPSSE VAIL IMMOBILIERE LLC RUBEN DARIO 115 TORRE 2 602 MEXICO D.F. CP 11580
MEXICO 210107222003 3 GCP INC AV CHAPULTEPEC 18 MEXICO DF 06640 MEXICO 210107222002 MARK GREENHILL REV TRUST ‐ELIZABETH GREENHILL REV TRUST ‐MARK GREENHILL FAMILY DESCENDANTS TRUST 153
SHERIDAN RD WINNETKA, IL 60093 210107222001 CAREY, ROBERT B. 6912 E HUMMINGBIRD LN PARADISE VALLEY, AZ 85253
Ever Vail Flood Plain Modification Permit 13 210107222007 SHARE SYNDICATE XIII LLC ALISON BUCHHOLTZ 675 LIONSHEAD PL VAIL, CO 81657 210107222008 JANICE SAUVAGE TRUST NO 1 8650 W TROPICANA
AVE 208 LAS VEGAS, NV 89147 210107222006 SCHICIANO, KENNETH 43 HIGHGATE RD WELLESLEY, MA 02481 210107222005 5 GCP INC AV CHAPULTEPEC 18 COL DOCTORES MEXICO DF MEXICO 2103‐014‐01‐068
TELLEEN, DANIEL E. 122 E MEADOW DR VAIL, CO 81657 2101‐063‐03‐015 JOSEPH O. BROUGHTON TESTAMENTARY TRUST 240 ASH ST DENVER, CO 80220 2101‐063‐03‐016 BROUGHTON, JOSEPH O., JR & LINDA
K. 240 ASH ST DENVER, CO 80220 2101‐063‐03‐014 RICHARD E. & MARTHA GRIFFITH DEAN TRUST, RICHARD E. & MARTHA GRIFFITH DEAN TRUSTEES PO BOX 970 TONGANOXIE, KS 66086 SIMBA RUN CONDOMINIUM
ASSOCIATION Farrow Hitt 1100 N FRONTAGE RD VAIL, CO 81657 BREAKAWAY WEST ASSOCIATION Christine A. Spaeth PO Box 3717, Eagle, CO 81631 BREAKAWAY WEST ASSOCIATION P.O. Box 1743, Vail,
CO 81658 SANDSTONE 70 CONDOMINIUM ASSOCIATION, INC. Vail Tax & Accounting, Inc. BOX 5940 AVON, CO 81620 81620 SANDSTONE 70 CONDOMINIUM ASSOCIATION, INC. PO BOX 1679 AVON, CO 81620 CDOT
4201 E. ARKANSAS AVENUE DENVER, CO 80222 MAURIELLO PLANNING GROUP, LLC POST OFFICE BOX 1127 AVON, CO 81620 2101‐072‐11‐032 VAIL RESORTS DEV THE FIXED ASSETS DEPARTMENT 390 INTERLOCKEN
CRESCENT STE 1000 BROOMFIELD , CO 80021 2101‐072‐23‐001 WDL Vail Condominium Association, Inc. Graham Frank Post Office Box 959, Avon, CO 81620 The Gore Creek Place Homeowner's Association
728 W. Lionshead Circle Vail, CO 81657
Ever Vail Flood Plain Modification Permit 14 VI. Attachments Attachment A: Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek Attachment B: Hydraulic Design
Drawings
South Frontage Road Bridge at Red Sandstone Creek Engineering Floodplain Analysis Prepared for Vail Resorts Development Company Prepared by AMEC Earth & Environmental 1002 Walnut Street
Suite 200 Boulder, Colorado 80302 P: 303.443.7839 F: 303.442.0616 www.amec.com January 18, 2011
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 1 AMEC Earth & Environmental Important Notice This floodplain analysis
report was prepared exclusively for Vail Resorts Development Company (VRDC) by AMEC Earth & Environmental, Boulder Office (AMEC). The quality of information, conclusions, and estimates
contained herein are consistent with the level of effort involved in AMEC’s services, and are based upon: i) information available at the time of preparation; ii) data supplied by outside
sources; and iii) the assumptions, conditions and qualifications set forth in this report. This report is intended to be used by Vail Resorts Development Company (VRDC) only, subject
to the terms and conditions of its contract with AMEC. Any other use of, or reliance on, this report by any third party is at that party’s sole risk. Client Contact: Sara Born Doug Laiho
AMEC Earth & Environmental, Inc. Boulder Office 1002 Walnut Street, Suite 200 Boulder, Colorado 80302 T. 303.443.7839 Doug.Laiho@amec.com saraborn@alpinehydroecology.com
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 2 AMEC Earth & Environmental TABLE OF CONTENTS 1.0 INTRODUCTION.....................
....................................................................3 2.0 FLOODPLAIN ENGINEERING ANALYSIS................................................3 2.1 EVALUATION OF THE EXISTING
FLOODPLAIN BOUNDARY AND DEVELOPMENT OF A NEW EFFECTIVE HEC-RAS MODEL...................4 2.2 NEW EFFECTIVE HEC-RAS MODELING RESULTS SUMMARY ............6 2.3 DEVELOPMENT OF A HEC-RAS
MODEL FOR THE PROPOSED CONDITIONS .............................................................................................7 2.4 PROPOSED CONDITIONS – HEC-RAS MODELING RESULTS SUMMARY
.................................................................................................9 3.0 CONCLUSIONS.....................................................................................
...11 4.0 ENGINEERING STATEMENT..................................................................12 Exhibits Exhibit A: Plan View of Floodplain Boundaries: existing FEMA, new effective
and proposed Exhibit B: HEC-RAS tabular results: New Effective Model Exhibit C: South Frontage Road Bridge Hydraulic Design Drawings Exhibit D: HEC-RAS tabular results: Proposed Conditions
Exhibit E: HEC-RAS Cross Sections: Proposed Conditions Attachments Attachment A: Existing FEMA floodplain boundary as produced by J.F. Sato and Associates Attachment B: Peak Land Consultants
Survey, October 8, 2008
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 3 AMEC Earth & Environmental 1.0 Introduction Vail Resorts Development
Company, in conjunction with the Town of Vail is planning on moving the I-70 South Frontage Road in West Lionshead to the north, immediately adjacent and parallel to the eastbound lanes
of I-70. This realignment will require the construction of a bridge across Red Sandstone Creek, directly south of the I-70 right-ofway. The purpose of this report is to address and evaluate
the hydraulic impacts associated with moving the South Frontage Road. The proposed project for the new South Frontage Road Bridge will require realignment and reconstruction of the Creek
channel from the I-70 CMP discharge location to a location approximately 185 feet downstream. The proposed bridge will be constructed using a Con/Span arch with a clear span of 42-feet.
The Con/Span arch is the structural component of the bridge that will span the creek. The bridge will be 99.35 feet wide. The span of the proposed bridge was developed using HEC-RAS
to model various stream geometries and bridge span options to identify a bridge span length that would not significantly impact water surface elevations or velocities of the Creek downstream
of the proposed bridge. Once this span length was determined the remaining design
characteristics were determined through an iterative process using Federal Highway Administration (FHWA) standards and HEC-RAS modeling. The primary design parameters were based on the
following objectives: maintain channel stability by armoring the new channel under the bridge to prevent scour during a 500-yr flood event, include channel geometry that is similar to
the existing stream geometry, and provide sufficient channel conveyance capacity to minimize changes to the existing 100-year water surface elevations downstream. The project area discussed
in this report starts at the discharge location for the existing I-70 CMP and ends 185-ft downstream, where the new channel meets grade with the existing channel morphology. 2.0 Floodplain
Engineering Analysis The intent of the engineering analysis is to review the existing Flood Insurance Study (FIS) floodplain boundary, define a new effective Base Flood Elevation (BFE)
using more recent topographic data, and define a new BFE for the proposed bridge design. The HEC-RAS files used to model the existing floodplain were acquired from FEMA and modified
to represent more recent and accurate survey data. The original FEMA HECRAS model will be referred to as the FIS HEC-RAS model. The model used to model the new effective BFE will be
referred to as the effective HEC-RAS model. The existing Flood Insurance study (08037CV000A) for Red Sandstone Creek was adopted by FEMA on December 4, 2007. The flood hazard area is
depicted on Eagle County, Colorado FIRM Panel 0837C046D as shown in Figure 2 (and included in Attachment A). The existing floodplain zone is defined as Zone AE floodplain. The existing
FEMA FIRM represents modeling of Red Sandstone Creek from the confluence with Gore Creek to approximately 2,900 feet upstream, just past Potato Patch Drive.
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 4 AMEC Earth & Environmental Figure 1. Existing FIRM panel for Red
Sandstone Creek 2.1 Evaluation of the Existing Floodplain Boundary and development of a New Effective HEC-RAS Model The cross section geometry modeled in FIS HEC-RAS model was examined
for accuracy and compared to more recent survey data to verify the precision of the geometry data in the vicinity of the project. Upon comparing the FIS cross sections to more recent
topographic data, discrepancies were revealed. Because of the numerous discrepancies between the FIS HEC-RAS geometric data and existing topographic data, Vail Resorts and Development
Company (VRDC) contracted Peak Land Consultants to resurvey the cross sections at the same locations along Red Sandstone Creek. Cross sections 406.5, 406, 405.5, 405.3, 405, 404, 403,
402.5, 402, and to 401.5 were surveyed on October 7, 2008. Three new cross sections were also surveyed at this time. This was done to provide more detail for the new effective floodplain
boundary analysis. Two of the new cross sections are located between cross
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 5 AMEC Earth & Environmental sections 404 and 405. These new cross
section identification numbers are 404.5 and 404.25. The third cross section is located just downstream of cross section 405.5, located just downstream of the I-70 CMP discharge. This
location was chosen because the cross section ID 405.5 intersects the culvert wing walls, and thus inaccurately represents the stream geometry downstream of the I-70 CMP discharge. The
cross section locations are shown in plan view in Exhibit A, and a hard copy of the design drawings are located in Attachment A. 2.1.1 Mannings n-Values Manning’s n-values for the main
channel and overbank portions of Red Sandstone Creek were not changed for the new effective model. The Manning’s n-values used are 0.04 and 0.05 for the main channel and the overbank
areas, respectively. This is congruent with field observations and aerial photographs. Red Sandstone creek is generally narrow and the streambed consists of cobbles and small boulders
and the floodplain is moderately vegetated. 2.1.2 Hydrology The hydrology used in the existing FIS model was adopted and used in the new effective model. 2.1.3 Boundary Conditions –
Flow Regime Boundary conditions were changed for the new effective baseline model. The existing FEMA model used a downstream boundary condition of 0.04 feet/feet. The model was run using
the sub-critical flow regime. The downstream boundary condition for the new effective model was set at normal depth, based on the average channel slope of 0.05 feet/feet. 2.1.4 Culvert
and Bridge Data Entrance and exit loss coefficients were not changed at stream cross sections for the new effective baseline model. Entrance and loss coefficients are 0.1 and 0.3 at
stream cross sections. Entrance and loss coefficients at the culverts are 0.5 and 1.0, respectively. The Entrance and loss coefficients at the existing South Frontage Road (Section ID’s
402.5 and 402) have been changed to 0.3 and 0.5, respectively. 2.1.5 Cross Sectional Geometry The new cross sectional data from the topographic survey was entered into the new effective
HEC-RAS model. The most notable changes to the geometry data are listed below. 1. Sections 406.5 and 406 have updated horizontal geometry to show flow in the horizontal plane, rather
than rising above I-70. The FIS HEC-RAS model showed flow overtopping I-70. 2. The I-70 CMP invert elevation on the north side of I-70 has been changed to 8120.3 feet. The FIS CMP invert
elevation value was 8124.3 feet. 3. The CMP invert elevation on the south side of I-70 was changed to 8107.90 feet. The FIS CMP invert elevation measurement was 8105.00 feet. 4. Cross
section 405.3 was added to represent the actual stream geometry downstream of the I-70 CMP. The new cross section is located 5 feet
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 6 AMEC Earth & Environmental downstream of cross section ID 405.5 This
new location was added because the existing section (ID 405.5) shows the wing walls of the CMP, and misrepresents the general existing channel geometry in that reach. 5. Cross sections
404.5 and 405.25 were added to provide more floodplain elevation data downstream of the new location for the South Frontage Road Bridge. 6. The CMP diameter has been changed to 7 ft.
The culvert diameter in the FIS HEC-RAS model was 6 ft. 2.2 New Effective HEC-RAS Modeling Results Summary The new effective HEC-RAS model was run using geometry data created from the
most recent survey. Model results in tabular format for the new effective model are presented in Exhibit B. Table 1 provides a summary table to compare the FIS and new effective water
surface elevations and velocities during a 100-yr event. Table 1. Water Surface Elevations and Velocities from FIS HEC-RAS model and the new effective HEC-RAS model. FIS Model Results
New Effective Model Results River Station ID W.S. Elev (ft) Vel Chnl (ft/s) W.S. Elev (ft) Vel Chnl (ft/s) 408 8158.02 7.66 8158.02 7.66 407 8140.04 7.63 8140.04 7.62 406.5 8139.2 0.93
8135.03 1.48 406 8139.21 0.84 8135.02 1.73 405.7 I-70 Culvert I-70 Culvert I-70 Culvert I-70 Culvert 405.5 8109.39 8.8 8110 10.02 405.3 n/a n/a 8108.82 8.45 405.25 n/a n/a 8107.62 3.1
405 8107.12 6.13 8106.77 5.9 404.5 n/a n/a 8099.98 6.16 404.25 n/a n/a 8097.96 6.08 404 8096.39 7.32 8096.35 7.68 403 8088.34 8.19 8089.03 6.51 402.5 8088.56 4.62 8089.06 4.76 402.3
Existing Frontage Rd. Bridge Existing Frontage Rd. Bridge Existing Frontage Rd. Bridge Existing Frontage Rd. Bridge 402 8085.54 7.7 8085.42 7.71 401.5 8083.53 7.54 8083.16 7.55 401 8077.2
5.75 8075.96 6.26 *An n/a value indicates those cross sections do not exist in the specified model.
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 7 AMEC Earth & Environmental The water surface elevations and velocities
changed at various cross section locations. The most notable changes are: 1. The water surface elevations at section ID’s 406 and 406.5 (north of I-70) decrease in elevation by approximately
4 feet. This is most likely due to the increased representation width of the floodplain at the cross sections. The existing FIS model truncated the sections and therefore there was no
representation of flow in the horizontal plane 2. Section ID 405.5 shows a higher water surface elevation in the new effective model. This is most likely a result of the FIS model not
representing the wing walls, while the new effective geometry represents the wing walls, and the immediate downstream stream morphology. 3. The water surface elevation at section ID
405 is lower in the new effective model. This is mostly likely a result of more detailed geometry that shows a more incised channel. 2.3 Development of a HEC-RAS model for the Proposed
Conditions The proposed bridge will be constructed using a Con/Span arch with a clear span of 42-feet. The Con/Span arch is the structural component of the bridge that will span Red
Sandstone Creek. The bridge will be 99.35 feet wide. The I-70 CMP will be shortened by 10 feet. Each end of the bridge will require a concrete headwall. The upstream headwall will be
located adjacent to the east bound lanes of I-70 and will retain the adjacent slope. In addition, this will provide an opening for the existing I-70 CMP to penetrate the wall. The CMP
will extend 1.9 feet beyond the edge of the upstream headwall to prevent seepage behind the retaining wall. The Con/Span arch will have 10 additional inches of vertical clearance over
the I-70 CMP. In order to convey flow through the Con/Span arch, the channel bed for Red Sandstone Creek is being adjusted to flow through the bridge. FHWA design specifications were
used to create the design details to protect the bridge and prevent scour of the channel during high flow events. The channel configuration is based on the need to protect the bridge
during high flow events and effectively manage flow during low flow events. A riprap energy dissipation basin has been designed to prevent scour and dissipate energy from flow out of
the I-70 CMP. The channel bed will be lined with grouted riprap with a median diameter of 18 inches. A drop structure and scour pool will be placed just downstream of the bridge to minimize
the longitudinal grade and limit further downstream impacts to Red Sandstone Creek. Detail design computations are included in the CDOT Hydraulic Report. The area to the west of the
creek, just downstream of the bridge, will be graded to create a gradual slope from the southern edge of the bridge face down to the creek. Note that the existing South Frontage Road
Bridge will not be removed as part of this project. The area will continue to be accessed via the existing South Frontage Road until the Ever Vail development is at or near completion.
Design drawings for the proposed project are located in Exhibit C.
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 8 AMEC Earth & Environmental The new effective HEC-RAS model was modified
to reflect the new South Frontage Road Bridge location, the realignment of Red Sandstone Creek, and the associated downstream grading changes. A project boundary has been defined by
identifying the cross sections where the water surface elevations and velocities have not been impacted by the proposed changes, i.e. the water surface elevation profiles match existing.
The project boundaries are cross sections 407 and 402. Cross section ID 407 is located 3 cross sections and 211 feet upstream of the I-70 CMP inlet. Cross section ID 402 is located immediately
downstream of the existing frontage road bridge. The water surface elevations and velocities return to existing values at or before these project boundary sections. A new grading plan
was created to represent the proposed changes associated with the new South Frontage Road Bridge. The new grading plan was used to create a 3-dimensional surface and cross sections using
RiverTools, a program extension to Civil 3D. This program creates cross sections in user specified locations and allows the user to export the geometry into HEC-RAS, as an .sdf file.
These cross sections are labeled in blue in Exhibit A. This data was then combined with the new effective HEC-RAS model to compute the impacts to the water surface elevations within
the proposed project area. A summary of the primary design changes incorporated into the proposed HEC-RAS model and associated geometry are listed below. 1. The downstream end of the
I-70 CMP has been cut back 10 ft. The culvert will now discharge directly into the 42 ft Con/Span arch. The new culvert invert elevation will be 8108.30 feet. 2. All cross-sectional
data between the I-70 CMP and the southern edge of bridge have been replaced with new geometry and numbered accordingly. This geometry represents the new riprap basin and the new stream
geometry. Note that the existing HEC-RAS sections were not always perpendicular to the flow line. The geometry data used for the proposed conditions model uses cross sections that are
perpendicular to the flow line. For this reason it is difficult to directly compare before and after water surface elevations based on cross section ID’s and location alone. When a cross
section line from the proposed model was crossing a cross section line from the new effective model it was given a section ID value 0.01 high or lower. If the proposed cross section
centerline was above the existing section line then the value was higher and vice versa. For comparison purposes the water surface elevation for the proposed conditions was interpolated
based on the plan view of floodplain boundary. Refer to Exhibit A for further clarification. 3. The width of the proposed bridge is 99.35-ft. For modeling purposes the bridge was shorted
to 49 feet long and placed downstream of the I-70 CMP stilling basin. This was done so that the stilling stilling basin could be represented in the hydraulic model. HEC-RAS will not
allow the modeler to enter a bridge and details for a stilling basin simultaneously. Note the upstream section of the bridge was modeled by creating stream geometry to represent the
walls of the bridge. 4. New cross sections were added downstream of the proposed bridge to represent the drop structure, scour pool, and grading downstream of the bridge.
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 9 AMEC Earth & Environmental The hydraulic attributes are the same
as those used in the new effective model. The following assumptions were used: The Manning’s n value used to model the reach through the bridge is 0.03. The remaining Manning’s n values
were consistently 0.04 and 0.05 throughout the model, as used in the existing HEC RAS model. The grouted riprap will be placed below the bridge so that it is protruding from the surface
in order to provide for increased roughness. Flow regime was modeled as subcritical when modeling the 100-yr water surface elevations. Note that the flow becomes supercritical at various
points due to the steep grade and drop structures, but FEMA requires the 100-yr floodplain boundary be calculated assuming subcritical flow. A mixed flow regime was used to determine
the depth of scour during a 500-yr flood event at the proposed bridge structure. The downstream boundary condition is the average channel slope of 0.05 feet/feet. Entrance and loss
coefficients are 0.1 and 0.3 at stream cross sections. The Entrance and loss coefficients at the existing South Frontage Road (Section ID’s 402.5 and 402) are 0.3 and 0.5. Entrance and
loss coefficients for the new bridge (405.3. and 405.15) are also 0.3 and 0.5. Entrance and loss coefficients at the culverts are 0.5 and 1.0, respectively. 2.4 Proposed Conditions –
HEC-RAS Modeling Results Summary The proposed HEC-RAS model was run with the new input data to determine the water surface elevations and velocities along Red Sandstone Creek under the
proposed conditions. The HEC-RAS model results indicate that the impacts to the 100-yr water surface elevations are less than a foot outside of the structures. In addition, the floodplain
width decreases in width due to the channelization of Red Sandstone Creek. Table 2 summarizes the results during a 100-yr flow event at key design locations. Note it is important to
view this this table in conjunction with Exhibit A to see the physical representation of the impacts to the floodplain boundary. The complete tabular results from the HEC-RAS model for
the proposed conditions are shown in Exhibit D. HEC-RAS model sections with the 100-yr water surface elevations for the proposed geometry are shown in Exhibit E. The FIS floodplain boundary,
the proposed new effective floodplain boundary, and the proposed floodplain boundary are shown in Exhibit A. Proposed vs. new effective ground and 100-yr water surface elevations are
shown in Figure 3.
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 10 AMEC Earth & Environmental Table 2. Proposed 100 yr Water Surface
Elevations at Key Design Locations (HEC-RAS section ID numbers are in parenthesis). New Effective BFE (100-yr flow) Proposed Conditions (100-yr flow) Location WSE (ft) Velocity (ft/s)
WSE (ft) Velocity (ft/s) ~ 200 ft upstream of the I-70 Culvert (407) 8140.04 7.62 8140.04 7.62 32 ft Downstream of the Bridge (404.5, 404.45) 8099.98 6.16 8100.50* 3.15 64 ft Downstream
of the Bridge (404.25, 404.24) 8097.96 6.08 8098.52* 8.28 162 ft Downstream of the Bridge (403) 8089.03 6.56 8089.02 6.59 Modeling Boundary – 223 ft Downstream of the Bridge (402) 8085.42
7.71 8085.42 7.71 *Value is interpolated based on the floodplain boundary because the proposed cross sections are perpendicular to the flow, while the existing cross sections are slightly
skewed from the perpendicular flow. Cross Section IDs in italics indicated a cross section value in the proposed conditions model. The cross section ID has been given a new value because
it crosses the existing cross section, but is slightly skewed from the existing conditions. This was done because the new cross section had to be adjusted to run perpendicular to the
flow line.
Floodplain Modification Permit – Engineering Floodplain Analysis South Frontage Road Bridge at Red Sandstone Creek 11 AMEC Earth & Environmental Profile for the 100-yr Water Surface
Elevation: Existing vs. Proposed Conditions 8070 8080 8090 8100 8110 8120 8130 8140 0 100 200 300 400 500 600 700 800 900 1000 Distance from cross Section ID 406 (located just upstream
of the I-70 CMP) Elevation (ft) New Effective Model Minimum Channel Elevation New Effective Model 100-yr WSE Proposed Conditions Minimal Channel Elevation Proposed Conditions 100-yr
WSE Figure 2. Proposed vs. Existing Ground Elevations and Water Surface Elevations during a 100-yr Flood Event. 3.0 Conclusions The floodplain analysis evaluated the existing adopted
Flood Insurance Study (FIS) floodplain boundary and created a new effective baseline model using more recent and accurate survey data. The new effective baseline model was then used
as the baseline model from which to create a new HEC-RAS model to represent the proposed design. This model shows a minimal increase in water surface elevation downstream of the project
area. The floodplain narrows just downstream of the new South Frontage Road Bridge, and shortly downstream returns to its existing configuration. The water surface elevation profiles
for the proposed conditions match the water surface elevation profiles of the new effective model at cross sections 407 and 402.5. FEMA requires that a Conditional Letter of Map Revision
(CLOMR) be submitted for review if the there has been a detailed hydrologic and hydraulic analysis for which the Base (1-percnet-annual-chance) Flood Elevations (BFEs) have been specified.
If the project area is within a floodplain boundary, but not designated as a regulatory floodway, then any changes that would result in more than a 1.0-foot increase in the BFE will
require a CLOMR. Red Sandstone Creek has a designated floodplain, but is not in a regulatory floodway. Although the increases to the BFE’s downstream of the proposed bridge are less
than 1.0 foot, the increases to the BFE’s within the proposed Con/Span arch are greater than 1.0 foot. Therefore, a CLOMR will need to be submitted to FEMA
Exhibit A: Plan View of Floodplain Boundaries: existing FEMA, new effective and proposed
Exhibit B: HEC-RAS tabular results: New Effective Model
Exhibit B. HEC-RAS tabular results: New Effective Model Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl (cfs)
(ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) Reach-1 415.5 100-year 490 8241.8 8253.94 8253.97 0.000082 1.18 414.36 56.81 0.08 Reach-1 415 100-year 490 8242.8 8253.93 8246.19 8253.96
0.000201 1.43 343.17 48.69 0.09 Reach-1 414.5 Culvert Reach-1 414 100-year 490 8235.4 8238.11 8238.11 8239.2 0.019791 8.37 58.53 27.33 1.01 Reach-1 413.8 100-year 490 8232.7 8235.6 8235.6
8236.58 0.030988 7.95 61.62 31.96 1.01 Reach-1 413 100-year 490 8221.9 8232.39 8232.41 0.000053 0.94 520.73 75.78 0.06 Reach-1 412.4 100-year 490 8221 8232.39 8224.57 8232.4 0.000061
1 488.14 70.83 0.07 Reach-1 412.3 Culvert Reach-1 412.2 100-year 490 8212.3 8215.28 8215.28 8216.37 0.03152 8.38 58.47 27.22 1.01 Reach-1 412 100-year 490 8211.4 8214.19 8214.19 8215.13
0.019618 7.79 62.88 33.89 1.01 Reach-1 411 100-year 490 8200 8201.96 8201.96 8202.75 0.020674 7.14 68.66 43.79 1 Reach-1 410.5 100-year 490 8188.8 8192.12 8192.12 8193.4 0.020075 9.09
53.91 21.09 1 Reach-1 410 100-year 490 8186.4 8189.59 8189.14 8190.29 0.011589 6.69 73.23 29.41 0.75 Reach-1 409.5 Bridge Reach-1 409.3 100-year 490 8184 8187.42 8187.42 8188.55 0.020111
8.54 57.37 25.77 1.01 Reach-1 409.2 100-year 490 8176.1 8182.61 8183.71 0.014519 8.41 58.29 17.91 0.82 Reach-1 409 100-year 490 8179 8181.22 8181.22 8182.07 0.020172 7.41 66.13 39.19
1.01 Reach-1 408 100-year 490 8156 8158.02 8158.02 8158.93 0.020057 7.66 64 35.43 1 Reach-1 407 100-year 490 8138 8140.04 8140.04 8140.95 0.019936 7.62 64.3 35.8 1 Reach-1 406.5 100-year
490 8125.55 8135.03 8135.07 0.000169 1.48 351.5 94.16 0.11 Reach-1 406 100-year 490 8124.23 8135.02 8127.79 8135.06 0.000246 1.73 335.5 102.32 0.12 Reach-1 405.7 Culvert Reach-1 405.5
100-year 490 8105.61 8110 8110 8111.56 0.02167 10.02 48.88 15.91 1.01 Reach-1 405.3 100-year 490 8104.18 8108.82 8108.82 8109.93 0.020174 8.45 57.96 26.82 1.01 Reach-1 405.25 100-year
490 8104 8107.62 8107.77 0.003864 3.1 158.15 100.06 0.43 Reach-1 405 100-year 490 8104 8106.77 8106.77 8107.31 0.023375 5.9 82.98 77.12 1 Reach-1 404.5 100-year 490 8096.43 8099.98 8099.98
8100.57 0.024028 6.16 79.6 70.06 1.02 Reach-1 404.25 100-year 490 8096.02 8097.96 8097.96 8098.53 0.023246 6.08 80.63 71.59 1.01 Reach-1 404 100-year 490 8092.96 8096.35 8096.35 8097.26
0.0223 7.68 63.79 35.55 1.01 Reach-1 403 100-year 490 8085.41 8089.03 8089.7 0.010955 6.56 74.66 33.03 0.77 Reach-1 402.5 100-year 490 8085.21 8089.06 8087.53 8089.41 0.003958 4.76 102.83
28.59 0.44 Reach-1 402.3 Bridge Reach-1 402 100-year 490 8082.39 8085.42 8085.42 8086.35 0.020029 7.71 63.54 34.5 1 Reach-1 401.5 100-year 490 8079.85 8083.16 8083.16 8084.04 0.019819
7.55 64.88 36.76 1 Reach-1 401 100-year 490 8073.13 8075.96 8075.96 8076.57 0.022281 6.26 78.28 64.82 1 1 of 1
Exhibit C: South Frontage Road Bridge Hydraulic Design Drawings
Exhibit D: HEC-RAS tabular results: Proposed Conditions
Exhibit D: HEC-RAS Tabular Results: Proposed Conditions Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl (cfs)
(ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) 1 415.5 100 yr 490 8241.8 8253.94 8253.96 0.000082 1.18 414.31 56.8 0.08 1 415 100 yr 490 8242.8 8253.93 8246.19 8253.96 0.000129 1.43
343.17 48.69 0.09 1 414.5 Culvert 1 414 100 yr 490 8235.4 8238.11 8238.11 8239.2 0.019791 8.37 58.53 27.33 1.01 1 413.8 100 yr 490 8232.7 8235.6 8235.6 8236.58 0.019832 7.95 61.62 31.96
1.01 1 413 100 yr 490 8221.9 8232.39 8232.41 0.000053 0.94 520.73 75.78 0.06 1 412.4 100 yr 490 8221 8232.39 8224.57 8232.4 0.000061 1 488.14 70.83 0.07 1 412.3 Culvert 1 412.2 100 yr
490 8212.3 8215.28 8215.28 8216.37 0.020173 8.38 58.47 27.22 1.01 1 412 100 yr 490 8211.4 8214.19 8214.19 8215.13 0.019618 7.79 62.88 33.89 1.01 1 411 100 yr 490 8200 8201.96 8201.96
8202.75 0.020674 7.14 68.66 43.79 1 1 410.5 100 yr 490 8188.8 8192.12 8192.12 8193.4 0.020075 9.09 53.91 21.09 1 1 410 100 yr 490 8186.4 8189.59 8189.14 8190.29 0.011589 6.69 73.23 29.41
0.75 1 409.5 Bridge 1 409.3 100 yr 490 8184 8187.42 8187.42 8188.55 0.020111 8.54 57.37 25.77 1.01 1 409.2 100 yr 490 8176.1 8182.61 8183.71 0.014525 8.41 58.28 17.91 0.82 1 409 100
yr 490 8179 8181.22 8181.22 8182.07 0.020172 7.41 66.13 39.19 1.01 1 408 100 yr 490 8156 8158.02 8158.02 8158.93 0.019908 7.64 64.16 35.44 1 1 407 100 yr 490 8138 8140.04 8140.04 8140.95
0.020068 7.64 64.16 35.79 1.01 1 406.5 100 yr 490 8125.55 8135.03 8135.06 0.000169 1.49 351.23 94.15 0.11 1 406 100 yr 490 8124.23 8135.02 8127.77 8135.06 0.000245 1.73 335.2 102.3 0.12
1 405.99 Culvert 1 405.9 100 yr 490 8107 8109.22 8109.22 8110.19 0.011452 7.9 62.04 32.3 1 1 405.8 100 yr 490 8104 8109.59 8109.7 0.000422 2.65 185.21 40.88 0.22 1 405.7 100 yr 490 8104
8109.59 8109.68 0.000329 2.48 199.55 40.88 0.2 1 405.6 100 yr 490 8106.89 8109.2 8109.65 0.004127 5.35 92.34 40.88 0.63 1 405.4 100 yr 490 8107 8108.72 8108.72 8109.55 0.011723 7.33
67.03 40.88 1.01 1 405.3 100 yr 490 8105.99 8108.3 8108.14 8108.98 0.008892 6.61 74.12 42 0.88 1 405.28 Bridge 1 405.15 100 yr 490 8099.12 8101.56 8101.56 8102.39 0.020792 7.32 66.97
41.07 1.01 1 405.1 100 yr 490 8098.76 8101.49 8102.04 0.010853 5.97 83.81 48.16 0.76 1 405.05 100 yr 490 8097.68 8101.69 8101.93 0.00296 3.99 130.76 58 0.42 1 405 100 yr 490 8096.48
8101.76 8101.89 0.001059 2.9 182.1 60.35 0.26 1 404.95 100 yr 490 8096 8101.78 8101.87 0.000617 2.49 216 63.44 0.21 1 404.9 100 yr 490 8096 8101.79 8101.87 0.000493 2.31 232.46 65.66
0.19 1 of 2
Exhibit D: HEC-RAS Tabular Results: Proposed Conditions 1 404.85 100 yr 490 8096 8101.78 8101.86 0.000514 2.33 224.77 62.31 0.19 1 404.7 100 yr 490 8096 8101.7 8101.85 0.001184 3.15
171.89 57.23 0.27 1 404.45 100 yr 490 8098.02 8101.48 8101.83 0.004291 4.93 113.88 52.53 0.51 1 404.4 100 yr 490 8098.02 8100.86 8100.86 8101.74 0.015878 7.86 70.24 41.8 0.94 1 404.3
100 yr 490 8096.81 8100.11 8100.11 8101.12 0.014268 8.47 67.62 35.98 0.91 1 404.24 100 yr 490 8095.77 8098.87 8098.87 8099.89 0.015344 8.28 64.89 35.8 0.93 1 404.2 100 yr 490 8095.11
8098.31 8098.31 8099.32 0.015415 8.21 65.13 37.26 0.92 1 404.12 100 yr 490 8093.6 8097.24 8097.24 8098.38 0.019029 8.6 57.17 27.13 1 1 403.99 100 yr 490 8092.34 8096.26 8096.26 8097.55
0.019488 9.11 53.78 21.2 1.01 1 403.95 100 yr 490 8091.27 8095.35 8095.35 8096.59 0.018437 8.95 55.44 23.89 0.99 1 403.8 100 yr 490 8090.39 8094.09 8094.09 8095.2 0.019528 8.43 58.12
26.9 1.01 1 403.79 100 yr 490 8088.84 8092.93 8092.93 8094.19 0.019391 9.03 54.27 21.76 1.01 1 403.78 100 yr 490 8087.48 8091.64 8091.64 8092.96 0.019801 9.2 53.24 20.54 1.01 1 403 100
yr 490 8085.41 8089.02 8089.7 0.011078 6.59 74.37 32.99 0.77 1 402.5 100 yr 490 8085.21 8089.05 8087.53 8089.41 0.003988 4.78 102.58 28.59 0.44 1 402.3 Bridge 1 402 100 yr 490 8082.39
8085.42 8085.42 8086.35 0.020029 7.71 63.54 34.5 1 1 401.25 100 yr 490 8079.85 8083.16 8083.16 8084.04 0.019819 7.55 64.88 36.76 1 1 401 100 yr 490 8073.13 8075.96 8075.96 8076.57 0.022227
6.25 78.34 64.84 1 2 of 2
Exhibit E: HEC-RAS Cross Sections: Proposed Conditions
1 of 19 0 20 40 60 80 100 120 140 160 180 8124 8126 8128 8130 8132 8134 8136 8138 8140 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 406 Station (ft) Elevation (ft) Legend EG 100 yr WS
100 yr Ground Bank Sta .05 .04 .05 Figure 1. HEC-RAS Cross Section ID 406 0 20 40 60 80 100 120 140 160 180 8124 8126 8128 8130 8132 8134 8136 8138 8140 RSC_Bridge Proposed Plan: Plan
04 10/25/2010 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 2. HEC-RAS Cross Section ID 405.99 Up
2 of 19 0 10 20 30 40 50 8105 8110 8115 8120 8125 8130 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .03 .03 .03
Figure 3. HEC-RAS Cross Section ID 405.99 down 0 10 20 30 40 50 8107.0
8107.5 8108.0 8108.5 8109.0 8109.5 8110.0 8110.5 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 405.9: Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .03 .03 .03
Figure 4. HEC-RAS Cross Section ID 405.9
3 of 19 0 10 20 30 40 50 8104 8105 8106 8107 8108 8109 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .03 .03
Figure 5. HEC-RAS Cross Section ID 405.8 0 10 20 30 40 50 8104 8105 8106 8107 8108 8109 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft) Elevation (ft) Legend EG 100 yr
WS 100 yr Ground Bank Sta .03 .03 Figure 6. HEC-RAS Cross Section ID 405.7
4 of 19 0 10 20 30 40 50 8106.5 8107.0 8107.5 8108.0 8108.5 8109.0 8109.5 8110.0 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground
Bank Sta .03 .03 Figure 7. HEC-RAS Cross Section ID 405.6 0 10 20 30 40 50 8107.0 8107.5 8108.0 8108.5 8109.0 8109.5 8110.0 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft)
Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .03 .03 Figure 8. HEC-RAS Cross Section ID 405.4
5 of 19 0 10 20 30 40 50 8105.5 8106.0 8106.5 8107.0 8107.5 8108.0 8108.5 8109.0 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 405.3: ACAD 625 Station (ft) Elevation (ft) Legend EG 100
yr WS 100 yr Ground Bank Sta .03 Figure 9. HEC-RAS Cross Section ID 405.3 0 10 20 30 40 50 8104 8106 8108 8110 8112 8114 8116 8118 8120 8122 RSC_Bridge Proposed Plan: Plan 04 10/25/2010
Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .03 Figure 10. . HEC-RAS Cross Section ID 405.28 Up
6 of 19 0 10 20 30 40 50 8095 8100 8105 8110 8115 8120 8125 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04
Figure 11. HEC-RAS Cross Section ID 405.28 0 10 20 30 40 50 8099.0 8099.5 8100.0 8100.5 8101.0 8101.5 8102.0 8102.5 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 405.15: ACAD 575 Station
(ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 Figure 12. HEC-RAS Cross Section ID 405.15
7 of 19 0 10 20 30 40 50 60 70 8098.5 8099.0 8099.5 8100.0 8100.5 8101.0 8101.5 8102.0 8102.5 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 405.1: ACAD 573 Station (ft) Elevation (ft)
Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 13. HEC-RAS Cross Section ID 405.1 0 10 20 30 40 50 60 70 80 8096 8098 8100 8102 8104 8106 8108 RSC_Bridge Proposed Plan:
Plan 04 10/25/2010 405.05: ACAD 570 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 14. HEC-RAS Cross Section ID 405.05
8 of 19 0 10 20 30 40 50 60 70 80 8096 8098 8100 8102 8104 8106 8108 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 405: ACAD 566 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr
Ground Bank Sta .05 .04 .05 Figure 15. HEC-RAS Cross Section ID 405 0 20 40 60 80 100 120 140 160 180 8095 8100 8105 8110 8115 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.95: ACAD
563 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 16. HEC-RAS Cross Section ID 404.95
9 of 19 0 20 40 60 80 100 120 140 160 180 8095 8100 8105 8110 8115 8120 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.9: ACAD 560 Station (ft) Elevation (ft) Legend EG 100 yr WS 100
yr Ground Bank Sta .05 .04 .05 Figure 17. HEC-RAS Cross Section ID 404.9 0 20 40 60 80 100 120 140 160 8096 8098 8100 8102 8104 8106 8108 RSC_Bridge Proposed Plan: Plan 04 10/25/2010
404.85: ACAD 552 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 18. HEC-RAS Cross Section ID 404.85
10 of 19 0 10 20 30 40 50 60 70 8096 8098 8100 8102 8104 8106 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.5: ACAD 545 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground
Bank Sta .05 .04 .05 Figure 19. HEC-RAS Cross Section ID 404.7 0 20 40 60 80 100 120 140 8098 8100 8102 8104 8106 8108 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.45: ACAD
542 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 20. HEC-RAS Cross Section ID 404.45
11 of 19 0 20 40 60 80 100 120 140 8098 8100 8102 8104 8106 8108 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.4: ACAD 538 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground
Bank Sta .05 .04 .05 Figure 21. HEC-RAS Cross Section ID 404.4 0 20 40 60 80 100 120 140 8096 8098 8100 8102 8104 8106 8108 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.3: ACAD 524
Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 22. HEC-RAS Cross Section ID 404.3
12 of 19 0 20 40 60 80 100 120 140 8094 8096 8098 8100 8102 8104 8106 8108 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.25: ACAD 511 Station (ft) Elevation (ft) Legend EG 100
yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 23. HEC-RAS Cross Section ID 404.24 0 20 40 60 80 100 120 8094 8096 8098 8100 8102 8104 8106 8108 8110 RSC_Bridge Proposed Plan: Plan
04 10/25/2010 404.2: ACAD 499 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 24. HEC-RAS Cross Section ID 404.2
13 of 19 0 20 40 60 80 100 120 8092 8094 8096 8098 8100 8102 8104 8106 8108 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 404.12: ACAD 86 Station (ft) Elevation (ft) Legend EG 100 yr
WS 100 yr Ground Bank Sta .05 .04 .05 Figure 25. HEC-RAS Cross Section ID 404.12 0 20 40 60 80 100 8092 8094 8096 8098 8100 8102 8104 8106 RSC_Bridge Proposed Plan: Plan 04 10/25/2010
403.99: ACAD 467 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 26. HEC-RAS Cross Section ID 403.99
14 of 19 0 20 40 60 80 8090 8092 8094 8096 8098 8100 8102 8104 8106 8108 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 403.95: ACAD 451 Station (ft) Elevation (ft) Legend EG 100 yr WS
100 yr Ground Bank Sta .05 .04 .05 Figure 27. HEC-RAS Cross Section ID 403.95 0 10 20 30 40 50 60 70 8090 8092 8094 8096 8098 8100 8102 8104 8106 RSC_Bridge Proposed Plan: Plan 04 10/25/2010
403.8: ACAD 438 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 Figure 28. HEC-RAS Cross Section ID 403.8
15 of 19 0 10 20 30 40 50 60 8088 8090 8092 8094 8096 8098 8100 8102 8104 8106 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 403.79: ACAD 407 Station (ft) Elevation (ft) Legend EG 100
yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 29. HEC-RAS Cross Section ID 403.79 0 10 20 30 40 50 60 8086 8088 8090 8092 8094 8096 8098 8100 8102 8104 RSC_Bridge Proposed Plan: Plan
04 10/25/2010 403.78: ACAD 386 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 30. HEC-RAS Cross Section ID 403.78
16 of 19 0 50 100 150 200 8085 8090 8095 8100 8105 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 403 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04
.05 Figure 31. HEC-RAS Cross Section ID 403 0 50 100 150 200 250 8085 8090 8095 8100 8105 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 402.5 Station (ft) Elevation (ft) Legend EG
100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 32. HEC-RAS Cross Section ID 402.5
17 of 19 0 50 100 150 200 250 8085 8090 8095 8100 8105 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04
.05 Figure 33. HEC-RAS Cross Section ID 402.3 Up 0 20 40 60 80 100 120 140 160 8080 8085 8090 8095 8100 8105 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 Station (ft) Elevation
(ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 34. HEC-RAS Cross Section ID 402.3 Down
18 of 19 0 20 40 60 80 100 120 140 160 8080 8085 8090 8095 8100 8105 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 402 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground
Bank Sta .05 .04 .05 Figure 35. HEC-RAS Cross Section ID 402 0 20 40 60 80 100 120 140 160 180 8075 8080 8085 8090 8095 8100 8105 8110 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 401.25
Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank Sta .05 .04 .05 Figure 36. HEC-RAS Cross Section ID 401.25
19 of 19 0 50 100 150 200 8070 8075 8080 8085 8090 8095 8100 8105 RSC_Bridge Proposed Plan: Plan 04 10/25/2010 401 Station (ft) Elevation (ft) Legend EG 100 yr WS 100 yr Ground Bank
Sta .05 .04 .05 Figure 37. HEC-RAS Cross Section ID 401
Attachment A: Existing FEMA floodplain boundary as produced by J.F. Sato and Associates
Attachment B: Peak Land Consultants Survey, October 8, 2008