HomeMy WebLinkAbout2018-105-11/06/2018-AUTHORIZING THE CITY MANAGER TO EXECUTE AN AGREEMENT WITH THE CITY OF GREELEY AND THE WATER SUPPLY A RESOLUTION 2018-105
OF THE COUNCIL OF THE CITY OF FORT COLLINS
AUTHORIZING THE CITY MANAGER TO EXECUTE AN AGREEMENT WITH THE
CITY OF GREELEY AND THE WATER SUPPLY AND STORAGE COMPANY
REGARDING A DAM BREACH FLOOD INUNDATION MAPPING STUDY
WHEREAS,the City owns two water storage reservoirs in the,upper Cache la Poudre River
basin: Joe Wright Reservoir and Halligan Reservoir ("City's Reservoirs"); and
WHEREAS, both of the City's Reservoirs are subject to the rules and regulations of the
State of Colorado's Office of Dam Safety in the Division of Water Resources, including the Rifles
and Regulations for Dam Safety and Construction, set out in at 2 Colorado Code of Regulations
402-1, which require, among other things,that all high hazard dams have an approved dam breach
inundation map showing the limits of the flooding associated with a failure of the dam under
certain conditions; and
WHEREAS, the City's Reservoirs are considered to be "high hazard dams" under said
regulations because they have dams "for which loss of human life is expected to result from failure
of the dam,"which is not meant to imply that the dams are actually anticipated to fail at this time;
and
WHEREAS, the City of Greeley ("Greeley") owns six water storage reservoirs with "high
hazard dams" in the upper Cache la Poudre River basin (Milton Seaman Reservoir, Barnes
Meadow Reservoir, Peterson Lake Reservoir, Comanche Reservoir, Hourglass Reservoir, and
Twin Lakes Reservoir) ("Greeley's Reservoirs"); and
WHEREAS, the Water Supply and Storage Company ("WSSC") owns two water storage
reservoirs with "high hazard dams" in the upper Cache la Poudre River basin (Long Draw
Reservoir and Chambers Lake) ("WSSC's Reservoirs"); and
WHEREAS; the dam breach inundation mapping for the City's Reservoirs, Greeley's
Reservoirs, and WSSC's Reservoirs is in need of updating; and
WHEREAS, the City can save money by collaborating with Greeley and WSSC on the
project to update the dam breach inundation mapping by reducing unnecessary duplication and
triplication of efforts; and
WHEREAS, the State of Colorado has grant funds that may be applicable to the project;
and
WHEREAS, staff from the City, Greeley, and WSSC have negotiated an agreement to
jointly update the dam breach inundation mapping,as set for the in draft Agreement attached hereto
as Exhibit "A".
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NOW,THEREFORE, BE IT RESOLVED BY THE COUNCIL OF THE CITY OF FORT
COLLINS as follows:
Section 1. That the City Council hereby makes and adopts the determinations and
findings contained in the recitals set forth above.
Section 2. That the City Manager is hereby authorized to execute an agreement
substantially in the form of Exhibit "A", with such modifications and additional terms and
conditions not inconsistent with this Resolution as the City Manager, in consultation with the City
Attorney, determines to be necessary and appropriate to protect the interests of the City or
effectuate the purposes of this Resolution.
Passed and adopted at a regular meeting of the Council of the City of Fort Collins this 6th
day of November, A.D. 2018.
Mayor
ATTEST:
K?�FORT�,O
•�s
City C
SE
AL
COLORA00
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EXHIBIT A
AGREEMENT BETWEEN THE CITY OF GREELEY,THE CITY OF FORT COLLINS,
AND THE WATER SUPPLY AND STORAGE COMPANY
REGARDING A DAM BREACH FLOOD INUNDATION MAPPING STUDY
This Agreement is entered into by and between the following Parties: the City of Greeley,
Colorado, a home rule municipality ("Greeley"); the City of Fort Collins, Colorado, a home rule
municipality ("Fort Collins"); and the Water Supply and Storage Company, a Colorado mutual
ditch and reservoir company ("WSSC"). Greeley, Fort Collins and WSSC are sometimes
hereinafter referred to as the"Parties"or individually as "Party".
RECITALS
A. The Parties each own and operate certain reservoirs located in the Cache la Poudre
River Basin above the canyon mouth, as listed below:
• Greeley: Milton Seaman Reservoir, Barnes Meadow Reservoir, Peterson Lake Reservoir,
Comanche Reservoir, Hourglass Reservoir, and Twin Lakes Reservoir.
• Fort Collins; Joe Wright Reservoir and Halligan Reservoir.
• WSSC: Long Draw Reservoir and Chambers Lake.
B. The Parties each intend to perform certain dam breach modeling, flood routing
modeling, generation of breach flood inundation GIS mapping, and related tasks and analyses for
their reservoirs("Study")as requested by the Dam Safety Office of the Colorado Division of Water
Resources ("CDWR").
C. By performing the Study jointly("Joint Study"), the Parties have each determined
that they would save time and money,be eligible for State grant funds, and benefit their respective
ratepayers,constituents, and shareholders.
D. Greeley has requested and received several proposals from consultants to perform
the analyses and other tasks associated with the Joint Study identified in the request for proposals.
The Parties have evaluated and selected a mutually agreeable proposal prepared by Anderson
Consulting Engineers, Inc. ("Consultant").
E. Greeley has agreed to retain the Consultant to perform the scope of work, attached
hereto as Exhibit A ("Scope of Work"), and to submit an application to CDWR for up to fifty
percent matching funds ("CDWR Grant") on behalf of the Parties. Fort Collins and WSSC have
agreed to reimburse Greeley for each respective Party's cost incurred on their behalf as described
in Exhibit B ("Budget"), and subject to the terms and conditions of this Agreement.
F. Greeley and Fort Collins are authorized to cooperate or contract with one another
to provide any function,service,or facility lawfully authorized to each of them pursuant to Article
H, Section 16 of the Charter of the City of Fort Collins and Article I, Section 1-3 of the Charter of
the City of Greeley and Title 2, Section 2.07.040 of the Municipal Code of the City of Greeley,
and C.R.S. §29-1-203(1).
Page 1 of 8
NOW THEREFORE, in consideration of the above-recited premises and the promises set
forth below, the Parties agree as follows.
AGREEMENT
1. DUTIES AND OBLIGATION OF THE PARTIES.
1.1. Greeley agrees to contract with the Consultant to perform the Scope of Work. Upon
completion of the Scope of Work and issuance of final payment, Greeley will also
submit an application for a CDWR Grant on behalf of the Parties. Fort Collins and
WSSC agree to provide Greeley with information and documentation necessary for
the CDWR Grant and Joint Study.
1.2. Fort Collins agrees to reimburse Greeley for the total cost of Task A as described in
the Budget and WSSC agrees to reimburse Greeley for the total cost of Task B as
described in the Budget. The total costs for Task A and Task B shall include any
additional costs incurred through authorized change orders. Payment shall be made
within 35 days of receipt of the invoice from Greeley.
1.3. The CDWR Grant is a cost-share program that reimburses a dam owner up to 50%
of the dam owner's cost of the Study, subject to certain terms and conditions
("Qualifying Dam"). If a CDWR Grant is awarded, Greeley will apply the funds as
a credit to each Task identified in the Budget, prior to invoicing Fort Collins and
WSSC. Greeley will allocate the CDWR Grant credit to each Task in an amount
equal to the Task's pro-rata share of the total cost. For example, the total cost is
anticipated to be$118,276, and the CDWR Grant is anticipated to be$59,135. Task
C's pro-rata-cost is currently estimated to be 52.78% ($62,430/$118,270 =0.5278)
of the total cost. Therefore,Task C would receive a credit of$31,211.50($59,135.00
* 0.5278 =$31,211.50). For purposes of determining the credit only, a Party's pro-
rata cost will be based on the cost of a Party's Qualifying Dam(s) and the total cost
will be determined based on the total cost of all Qualifying Dams.Ifa dam identified
in the Budget does not meet the terms and conditions of the CDWR Grant and the
CDWR Grant is reduced accordingly,then no CDWR Grant funding will be applied
to the cost of that dam..For example,if Bames Meadow Reservoir is not a Qualifying
Dam (solely for the purpose of this hypothetical example) and the CDWR Grant is
reduced from $59,135 to $53,805 ($59,135 — ($10,660 * 0.5) = $53,805)
accordingly,then the cost of Bames Meadow would be subtracted from the total cost
of$118,270 to $107,610 ($118,270 - $10,660 = $107,610) to determine Task C's
pro-rata-cost and portion of the grant. Thus, Task C's pro-rata-cost for Qualifying
Dams would be 48.10% (($62,430- $10,660)/$107,610=0.4810) of the total cost,
and receive a credit of$25,880.20 ($53,805 *0,4810= $25,880.20).
2. FORT COLLINS AND WSSC COOPERATION WITH THE STUDY. Fort Collins
and WSSC agree to cooperate in good faith with Greeley and/or the Consultant to complete the
Scope of Work and to secure the CDWR Grant including, but not limited to, providing a currant
Emergency Action Plan and information and documentation necessary to complete the Scope of
Page 2 of 8
' Work and/or secure the CDWR Grant. If a Party does not provide the required information and
documentation necessary to secure its pro-rata share of the CDWR Grant, then that Party may
forfeit their pro-rata share of the anticipated CDWR Grant as determined by CDWR.
3. DELIVERABLES. Greeley shall provide Fort Collins and WSSC with copies of the
deliverables, identified in Sub-Task 3 of the Scope of Work ("Deliverables") for their respective
dams within 30 days of Greeley's receipt of the same, subject to the terms and conditions of this
Agreement, such as Paragraph 6.
4. NO ENDORSEMENT'OF OTHER PARTY'S PROJECTS OR RIGHTS. A Party's
cooperation in this Agreement and Study is not an endorsement of the other Party's various
projects or rights (including,but not limited to,water rights)and shall not limit the rights of a Party
to fully participate in any proceedings regarding the other Party's various projects or rights.
5. RIGHT TO TERMINATE. Any Party may terminate this Agreement, with or without
cause, upon written notice to the other Party pursuant to Paragraph 11. If this Agreement is
terminated, Fort Collins and WSSC shall be responsible for all reimbursement payments due to
Greeley as of the date of termination, and shall only be entitled to a copy of the Deliverables for
their respective dams if it has made all payments due to Greeley under this Agreement, provided
that Fort Collins or WSSC shall not be required to return any Deliverable it has possession of as
of the date of termination.
6. FISCAL CONTINGENCY. Notwithstanding any other provision of this Agreement to
the contrary, the obligations of Greeley and Fort Collins ("Public Entity" in this paragraph) in
fiscal years after the fiscal year of this Agreement shall be subject to appropriation of funds
sufficient and intended therefor, with the Public Entity having the sole discretion to determine
whether the subject funds are sufficient and intended for use under this Agreement,and the failure
of the Public Entity to appropriate such funds shall be grounds for the Public Entity to terminate
this Agreement with written notice pursuant to Paragraph 11.
7. REMEDIES. If any Party fails to comply with the provisions of this Agreement,the other
Party, after providing written notification to the noncomplying Party, and upon the failure of the
noncomplying Party to achieve compliance within 35 days, may seek all such remedies available
under Colorado law.
8. NO THIRD-PARTY BENEFICIARIES. This Agreement is entered into between the
Parties for the purposes set forth herein. It is the intent of the Parties that they are the only
beneficiaries of this Agreement and the Parties are only benefitted to the extent provided under the
express terms and conditions of this Agreement.
9. GOVERNING LAW AND ENFORCEABILITY. This Agreement shall be construed
in accordance with the laws of the State of Colorado. The Parties recognize that the constitutions,
statutes, and rules and regulations of the State of Colorado and of the United States, as well as the
Parties' respective bylaws,city charters and codes, and rules and regulations,impose certain legal
constraints on each Party and that the Parties intend to carry out the terms and conditions of this
Page 3 of 8
Agreement subject to those constraints.Whenever possible,each provision of this Agreement shall
be interpreted in such a manner so as to be effective and valid under applicable law.
10. WAIVER A waiver of a breach of any of the provisions of this Agreement shall not
constitute a waiver of any subsequent breach of the same or another provision of this Agreement.
Nothing in this Agreement shall be construed as any waiver of governmental immunity of the
Parties who are governments or any other governmental provisions of State law. Specifically,by
entering into this Agreement, neither Party waives the monetary limitations on liability or any
other rights,.immunities, or,protections provided by the Colorado Government Immunity Act,
C.R.S. § 24-10-101, et seq., or any successor or similar statutes of the State of Colorado.
11. NOTICES. All notices or other communications hereunder shall be sufficiently given and
shall be deemed given when personally delivered,or after the lapse of five business days following
mailing by certified mail-return receipt requested, postage prepaid, addressed as follows:
To Greeley: Greeley Water and Sewer Department
Attn:Deputy Director of Water Resources
1001 11th Avenue, 2nd Floor
Greeley, Colorado 80631
With a copy to: Greeley City Attorney's Office
Attn: Environmental and Water Resources
1100 10t'Street, Suite 401
Greeley, Colorado 80631
To Fort Collins: City Manager
City Hall West
300 LaPorte Avenue; P.O. Box 580
Fort Collins, Colorado 80522-0580
With copy to: Fort Collins City Attorney
300 LaPorte Avenue; P.O. Box 580
Fort Collins, Colorado 80522-0580
epotyondy@fcgov.com
and: Fort Collins Utilities
Attn: Director of Plant Operations
4316 LaPorte Avenue
Fort Collins, Colorado 80521
mkempton @fcgov.com
To WSSC: The Water Supply and Storage Company
2319 Mulberry Street
Fort Collins, Colorado 80522
With a copy to: Fischer,Brown,Bartlett&Gunn, P.C.
Page 4 of 8
1319 East-Prospect Rd.
Fort Collins, CO 80525
12. CONSTRUCTION. This Agreement shall be construed according to its fair meaning as
it was prepared by the Parties. Headings in this Agreement are for convenience and reference only
and shall in no way define, limit, or prescribe the scope or intent of any provision of this
Agreement.
13. ENTIRE AGREEMENT. This Agreement constitutes the entire agreement of the Parties
regarding the matters addressed herein. This Agreement binds and benefits the Parties and their
respective successors. Covenants or representations not contained in this Agreement regarding the
matters addressed herein shall not bind the Parties.
14. REPRESENTATIONS. Each Party represents to the other parties that it has the power
and authority to enter into this Agreement and the individual signing below on behalf of that Party
has the authority to execute this Agreement on its behalf and legally bind that Party.
15. ASSIGNMENT. No Party may assign any rights or delegate any duties under this
Agreement without the written consent of all other Parties.
16. COUNTERPARTS.This Agreement may be executed in any number of counterparts each
of which, when taken together, shall constitute one agreement. This Agreement shall only be
effective when counterparts are signed by the all the Parties.The Agreement may be executed and
delivered by electronic signature by any Party and all Parties consent to the use of electronic
signatures.
[Remainder of Page Left Blank Intentionally]
I
Page 5 of 8
CITY OF GREELEY,COLORADO,a home rule municipality
By: Date:
John Gates,Mayor
ATTEST:
By:
Betsy Holder, City Clerk
AS TO SUBSTANCE:
By:
Roy Otto,City Manager
AS TO LEGAL FORM:
By:
Doug Marek, City Attorney
AS TO AVAILABILITY OF FUNDS:
By:
Victoria Runkle, Director of Finance
Page 6of8
CITY OF FORT COLLINS, COLORADO,a Colorado home rule city
By: Date:
Darin A. Atteberry, City Manager
ATTEST:
By:
City Clerk
APPROVED AS TO LEGAL FORM:
By:
Eric Potyondy, Assistant City Attorney
City Attorney's Office
Page 7 of 8
WATER SUPPLY AND STORAGE COMPANY, a Colorado mutual ditch and reservoir
company
By: Date:
Keith Amen, President
ATTEST:
By:
Page 8 of 8
EXHIBIT A
to
AGREEMENT BETWEEN THE CITY OF GREELEY, THE CITY OF FORT COLLINS,
AND THE WATER SUPPLY AND STORAGE COMPANY
REGARDING A DAM BREACH FLOOD INUNDATION MAPPING STUDY
(Scope of Work)
EXHIBIT A
SCOPE OF WORK
DAM BREACH FLOOD INUNDATION MAPPING
CITY OF GREELEY,CITY OF FORT COLLINS,AND WATER SUPPLY&STORAGE CO.
OCTOBER 12,2018
This scope of work includes tasks needed to provide dam breach flood inundation mapping for ten dams
located within Poudre Canyon. Dams included in this study are listed below.
City of Fort Collins Dams City of Greeley Dams
• Joe Wright Reservoir • Barns Meadow Reservoir
• Halligan Reservoir • Comanche Reservoir
Water Supply and Storage Company Dams • Seaman Reservoir. Hou• ass Reservoir
• Long Draw Reservoir
• Chambers Lake Reservoir
• e e ,n ke Reservoir
• 1 n" s servoir
The study area includes approximately 116 miles of the Cache la Riveo dre River)upstream of
its confluence with the South Platte River,6.7 miles of `i t Cr a 1 miles of La Poudre Pass Creek,
6 miles of Beaver Cmek,16 miles of the South Fork he C I oudr' River(South Fork),and 24 miles
of the North Fork of the Cache la Poudre Riv_r,'(Nq h k). a 1 'illustrates the location of all ten
reservoirs relative to the river network that; ns the
il3am ner, Halligan
ly
Fort �14
Collins m 1
ti
p �
e
Poudre River E
AMN&Osmi Joe7,�,rI tCk 26.7mI mi mi
o� 3.2 ml
Joe 03m� n 1L
L
Wright e
Y ra h Souih Platte
Conflueme
V e)�
c I
m a
3
01
LI
�Mn,
eQaSS ° A
a m Nottoscale.
e°Jai I
I
Figure 1 Dam Location and River Network of Study Area
Exhibit A Exhibit A,Page 1
TASKS A,B,AND C
This scope of work is divided into three major tasks (Tasks A, B, and C) which are grouped by dam
ownership. Task A applies to City of Fort Collins Dams, Task B applies to Water Supply and Storage
Company Dams,and Task C applies to City of Greeley Dams. Tasks A,B,and C are comprised of three Sub-
tasks including:Sub-Task 1 Breach Modeling,Sub-Task 2 Flood Routing and Inundation Mapping,and Sub-
Task 3 Development of Deliverables.
SCOPE OF SUB-TASKS
The three subtasks described below will be conducted to produce inundation mapping for each of the 10
dams described and included in Tasks A, B, and C. All work shall be performed in accord with: 1) 'Rules
and Regulations for Dam Safety and Dam Construction"(DWR 2007) and 2) "Guidelines for Dam Breach
Analysis"published by the Colorado Office of the State Engineer(DWR 2010).
SUB-TASK 1 BREACH MODELING
This task includes items required to conduct breach modelih for Of
iv dual dam.
SuB-TASK 1.1 BREACH MODELING DATA COLLECTION
The following information and data will be obtainedi d� viewed' a inform development of breach
parameters and breach modeling. Information and data I .__u e,but is not limited to:
• State Engineer records including dam as-bGi plans AM stagej-storage curves
• Additional dam information from the damowners
.j
• Best available topography ;-. ~~~.••••"'///
SUB-TASK 11 DEVELOPME OF DAM BRE CH[PARAM RS
`.
Dam breach parameters Inelud�ing geometzryf and time to failure will be developed using empirical
equations recommended by The;,ColDradro4State Engineers Office Dam Safety Branch and described in
"Guidelines for Dam Breach An ys/si.(DW,;R'2010).Methodologies for dam breach parameter estimations
will include MacDonald&Langridge-Wlonopolis(1984),State of Washington Method(2007),and Froehlich
(2008).Evaluation of Halligan Dam will assume a structural failure of the concrete structure.
Sue-TASK 1.3 BREACH MODELING
Breach modeling will be conducted using the USACE's HEC-RAS Version S.O.S. Dam embankment
geometry, breach parameters,stage vs storage curves, and downstream channel geometry will be input
into HEC-RAS to produce an outflow hydrograph, Multiple breach scenarios may be run for individual
dams depending upon configuration of the dam's embankment and outlet works.The resulting outflow
hydrograph with the largest peak discharge will be used as input to the 2D HEC-RAS models for flood
routing and inundation mapping.
The"Guidelines for Hazard Classification"(DWR 2010)states that:"if failure of the subject dam can cause
the failure of another dam or series of dams located downstream the cumulative dam break flood wave
must be considered...." A cumulative dam break analysis will be evaluated for Task A dams including Joe
Wright and Halligan Reservoirs.Joe Wright Reservoir is located on Joe Wright Creek approximately three
Exhibit A Exhibit A,Page 11
miles upstream of Chambers Lake Reservoir. Similarly, Halligan Reservoir is located on the North Fork
approximately 22 miles upstream of Seaman Reservoir, The attenuated breach hydrograph from the
subject dam (either Joe Wright or Halligan) entering a downstream reservoir (either Chambers Lake or
Seaman) will be compared with the capacity of the emergency spillway of the downstream reservoir. If
the peak discharge of the attenuated breach hydrograph is larger than the emergency spillway capacity
cumulative dam break evaluation may be necessary.The final approach to breach modeling of Joe Wright
and Halligan Reservoir will be guided by review and input from the Dam Safety Branch and the owners of
the dams.
SUB-TASK 1.4 BREACH MODELING REVIEW/MEETING WITH DAM SAFETY BRANCH AND DAM OWNERS
Dam breach parameters and results of initial breach modeling will be provided to the Dam Safety Branch
and Dam Owners for discussion and review.Commencement of flood routing and inundation mapping
(Sub-Task 2)will begin upon final approval of breach modeling.
SUB-TASK 2 FLOOD ROUTING AND INUNDATION MAP G
Three two-dimensional hydraulic models will be develope to=, duct 'oud outing and inundation
mapping. Hydraulic modeling will be conducted us SAC '`�;HEC-RAS 2D Model Version 5.0.5.
Model extents were chosen based upon location ohms, r confluences, and potential cumulative
failure analyses. Figure 2 shows a schematics d ie t -ach E AS 2D model. The'Poudre Canyon
2D Model'will include the Joe Wright Creek L I udre �s Cr ` ,Beaver Creek,the South Fork,and the
Poudre River upstream of the No Fork Co fl nce an I I - utilized to analyze eight of the ten dams.
The 'North Fork 2D Model' d-Ucove t e No h Fork below Halligan Reservoir and will be applied to
evaluations of Halligan a Si aman Rese o . .Th udre River 2D Model'covers the lower 60 miles of
the river between the 0 Fork and its c 0 uence with the South Platte River. The 'Poudre River 2D
Model'will be utilized for l t damS.
aAS Model Cwerg Halligan
8 e
Poudre Canyon 2D Model
North Fork 2D Model
Poudre River 20 Model
._Joe-Wright Ck. _.Poudre River.
O
NM
r(ghIt
n,ne
V wnn�ence
c
m
3
o �
n
v �eQ y m I
Figure 2 Schematirof HEC-RAS 2D Model Extents
ExhibitA Exhibit A,Page 12
SUB-TASK 2.1 DATA COLLECTION
This task includes collection of data required for development of the HEC-RAS 2D models and production
of inundation mapping. Data to be collected includes, but is not limited to:
• 2013 Post Flood LiDAR(USGS/Photo Sciences,Inc.)
• 2009 LiDAR on North Fork Poudre(Halligan Supply Project, Fugro Horizons,Inc)
• USGS 10 Meter Digital Elevation Models(10-meter DEM)
• Best available color NAIP aerial photography from the USDA(2011 or newer)
• Effective FEMA 100-year floodplain mapping along the Poudre River
• Available GIS data including but not limited to identification of critical facilities,critical sections roads,
and jurisdictional boundaries from municipalities and counties(Larimer County,Weld County,City of
Fort Collins,Town of Timnath,Town of Windsor, and City of Greeley)
• National Land Cover Dataset(USGS)
SUB-TASK 2.2 GIS DATA PREPARATION AND TERRAIN DEVELOPMENT
This task includes of all GIS data needed for in t, '
preparation p' � o t e HE 2D modeling. Cost for this
task is pro-rated by estimated length of inundation mapping or each dam
A digital terrain model for each model will be develo dgbyrACE's G15yspeciahsts. Multiple topographic
ii'e :J
sources will be stitched together to produce a sing e�terrairiZ eeded as input to HEC-RAS. The following
1.. f V .
topographic sources will be used to develop tefrain3for t e Corresponding HEC-RAS 2D model indicated
below.
• Poudre Canyon 2D Modelerrai ' F
0 2013 Post Flo,��o-�I AR 1)Poud�r�-Rlve�bgw een the South Fork and North Fork;2)South Fork
o USGS 10 M€ter�EM.1)Poudre'R*er between La Poudre Pass Creek to the South Fork;2)Joe
�-.'
Wright Creek,L*Poudre Pass Cr ek,Beaver Creek
• North Fork 2D Model Te ain�2009 Li A full coverage
\y�
• Poudre River 2D Model Terrain;2z_Oli1 ost Flood LiDAR—full coverage
The digital terrain models will be clipped to the river corridor to reduce file size and model run times.
Digital land coverage from the National Land Cover Dataset(USGS)collected as part of Sub-Task 2.1 wlll
be used to create a manning's n shape file that will be applied to the model grid to compute surface
roughness. Manning's n coverages will be developed at a course scale. A shape file including break lines
delineating major roads, embankments, or land features will also be developed using available GIS data
(transportation lines, levee lines, etc.) and engineering judgement. Break line development will be
conducted at a course scale. Critical section identified by municipalities will be included in the model
where detailed output(peak flow, arrival time,flood depth,and flood velocity) is needed.
Exhibit A Exhibit A,Page 13
SUB-TASK 2.3 HEC-RAS 20 MODEL DEVELOPMENT
This task includes development of each of the three HEC-RAS 2D models.Data developed in Sub-Task 2.2
including the digital terrain, Manning's n shape file, break line shape file, location of critical facilities,
location of critical sections will be used to build the HEC-RAS 2D models.
Cost of model development is be pro-rated by the estimated distance of inundation mapping for dams
utilized by each model. Table 1 summarizes the estimated length of inundation mapping that will be
produced by each model for individual dams.The estimated mileage was used to pro-rate costs.
Table 1 Flood.Routing and Inundation Mapping Model Usage
E,:P uo Tdre ea yn on 2D`M del ,FZ.> , W28N Fork ZO(M el'G ti Poudre3Riv''er 3D+IYlodel
� r --'�.':-i' -3 c• �"�LSr F�1 ITI$"�^' ry... -n u-—"°J`f_-"n pal'
��ITI
„� .K I]`-.rptiYl 1; •v' c�s]- ESt nr}pC/-� LSJ{ f+:q-ykl} L;��1• E.St��t� +r:l iy y n SII V. iiV Gam` v. 1
sy„R a.U@ "I''Dam,Y�tt;"•�, �.e'rT��;HUsa a
Joe Wright Reservoir 52 ini Halligan Reservoir 22 mi oe Wright Reservoir 60 mi
Long Draw Reservoir 57 mi Seaman Reservoir alligan Reservoir 60 mi
Chambers Lake 49 mi ng Draw Reservoir 60 mi
Comanche Reservoir 40 mi a bers Lake 60 mi
Barns Meadow Reservoir 48 mi Seaman ervoir 60 mi
Hourglass Reservoir 39 mi Comanch` Reservoir 60 mi
Peterson Lake Reservoir 51 mi .::: %rgl.sMeadow Reservoir 22 mi
Twin Lakes Reservoir 36 miass Reservoir 22 mi
y Peterson Lake Reservoir 4 mi
Twin Lakes Reservoir 4 mi
SUB-TASK 2.4 PREPARATION OF TI N PING
This task includes prepay n of base ma i g tha ' ill consolidate and streamline inundation mapping
production. Project wid�ase mapping an Ua out of mapping sheets will be developed in GIS to create
a mapping template. Mapp`i` eets will be 1x17 in size and at a scale of approximate) 1:1,000. All
�g Y
printed map sheets will include thte llo Ing information:
• Dam name and DAM ID • Annotation of roads,highways,and
• North arrow and graphic scale landmarks
• Dam break inundation boundaries • A table providing initial flood wave arrival
• Effective FEMA 100-year floodplain time, peak flood arrival time,peak
• Critical facilities and critical sections discharge,peak flood wave depth,and
• Jurisdictional boundaries peak flood wave velocity for critical
• Color aerial photography(2011 and newer) facilities/sections
This task also includes set up of attribute tables for critical facilities and critical section GIS shape files that
identifythe initial flood wave arrival time,peak flood arrival time,peak discharge, peak flood wave depth,
and peak flood wave velocity.
Cost of this task is pro-rated by the estimated length of inundation mapping for each dam.
Exhibit Exhibit A,Page 14
SUB-TASK 2.5 FLOOD ROUTING AND INUNDATION MAPPING
This sub-task includes items needed to run the HEC-RAS 2D models, produce inundation mapping, and
production of GIS deliverables. Cost for this task is specific to each dam.
Modifications to the HEC-RAS 2D models to allow for flood routing and inundation mapping for a specific
dam will be conducted. Modification will include input of appropriate inflowing hydrographs(developed
in Sub-Task 2.3), setup of downstream boundary conditions, and reduction of the 2D model area if
necessary. Multiple model runs may be necessary to map multiple flow paths when the dam breach
location differs from the spillway. Initial inundation boundaries and detailed hydraulic output will be
extracted for post-processing.
Post processing of model output will be conducted by ACE's GIS specialist. The downstream limit of
inundation mapping will be identified where it falls below the level of the effective FEMA 100-year
floodplain on the Poudre River.The downstream limit of inundation mapping will be tied into the 100-
year floodplain delineation on the maps. Inundation mappigxg nea t'he dam may include multiple flow
paths through the embankment or spillway. If the spillway;flow Path4s d�dam breach flow path are not
coincident, then mapping of the peak spillway discharge wii�{;be�iI cluded�ar ddttied into the dam breach
flow path inundation boundaries. The final inundation bot4ndari swill b''j rep red in ESRI shape file
format that references UTM coordinates (NAD 83, Zone R Ineterrss`The attribute tables for the critical
facility and critical section GIS shape files will be pop eX� t, e HE R�2D detailed hydraulic output
(initial flood wave arrival time,peak flood arrival tire, pea disc ge, peak flood wave depth,and peak
.y
flood wave velocity). A set of inundation maps will be pYoduced for each dam using the template
developed in Sub-Task 2.4.
SUB-TASK 3 DELIVERABLES "
Deliverables will be produce d(in dividually fOr each dam and will include the Inundation Mapping Report
(including color inundation maaD )). a CDcontaining digital inundation boundaries and critical facilities
shape files,PDFs of the report and mu tl lion maps,supporting spreadsheets, and all HEC-RAS models.
A single Inundation Mapping Report template will be developed to produce an individual report for each
dam. Use of a template promotes efficiency and consistency in the production of reporting to keep costs
down. Cost to develop the template is split evenly between the ten project dams.
SUB-TASK 3.1 PRELIMINARY REPORTING
For each dam the data collection effort, base mapping, calculated dam breach parameters, hydraulic
analyses'assumptions/methodologies/results,and dam break inundation mapping will be summarized in
a draft Inundation Mapping Report that will be submitted to the Dam Safety Branch for review. The report
will be prepared in both Microsoft WORD and Adobe Acrobat PDF formats and shall include:
• A narrative that describes the background of the project,the data collected as part of the project,
including the base mapping, the estimation of the dam breach parameters, and the hydraulic
analyses and inundation mapping methodologies for the project;
Exhibit A Exhibit A, Page 15
o Tables summarizing the initial flood wave arrival time, peak flood arrival time, peak discharge,
peak flood wave depth,and peak flood wave velocity at all critical facilities and critical sections;
and
o Dam failure inundation maps in Adobe Acrobat and ESRI's ArcGIS format.
Upon receipt of review comments from the Dam Safety Branch,ACE will revise the preliminary report to
produce the Final Inundation Mapping Report in both hard copy and digital formats as specified in'the
RFP.
Sue-TASK 3.2 FINAL REPORTING
Two hard copies of final Inundation Mapping Report for each dam,including the inundation maps,will be
stamped by the ACE Project Manager, who is a registered Professional Engineer in the State of Colorado.
The final reports(total of 10)and all deliverables will be submitted to the Dam Safety Branch. Each Project
Partner will receive one hardcopy report for their own dams.
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Exhibit Exhibit A, Page 16
EXHIBIT B
to
AGREEMENT BETWEEN THE CITY OF GREELEY,THE CITY OF FORT COLLINS,
AND THE WATER SUPPLY AND STORAGE COMPANY
REGARDING A DAM BREACH FLOOD INUNDATION MAPPING STUDY
(Budget)
EXHIBIT B
BUDGET
DAM BREACH FLOOD INUNDATION MAPPING
CITY OF GREELEY,CITY OF FORT COLLINS,AND WATER SUPPLY&STORAGE CO.
OCTOBER 12,2018
Table 1 Project Budget
Sub-Task 1 Sub-Task 2 Sub-Task 3
Breach Flood.Routing Deliverables ODC'S Total
Modeling &Inundation
Mapping
y}�y� ,a 'F i`+ ,...flTY�tr §� `�7.�.i!'�.� r��f�f. ! 4` r L�.}Vf yj, +5:��°?cC�•p ap'y'"+'�"•t r'1!>,'L�. +i �C •C �y+-.yz aFfz.:
. TaskyAi�C��F��t�01�1�^cD-amu.sazV..u�L'.z..":tti4L��}L`+Vs'x?�.htt�,•.:i'S?if�C•1dn�erFk.�k5f��� � i�iw,� -.�f f41S32�380i<�;=
Joe Wright Reservoir $3,660 $6,600 $90 $13,590
Halligan Reservoir $3,600 $11,800 $ $70 $18,770
i•`T3'i°�.'TT11urT.4t ur'ia.Ectii�-" e f v,s:'Y-ro ryT"C'LStL.a7A�.t? mie ."; t. �Yt"d=njaf'f"'fi��.a r,�:!•+�w:y-aossr+. 1
Task Bra Wate,�r;Su�ptply antltStorage Company Damn �i� �'�',��., u ;41,tir«•�ly¢ '�- =zr,�$23;480i�`�;�
Long Draw Reservoir $2,200 $6,300 0 90 $11,890
Chambers Lake $2,200 $6,0 $3, $90 $11,590
--o""'� vi r1�c. ! •`.'Ft. Ff'a r, :^.s;+n--- •�.xacu-
TaskC. Cty;ofaGreeley Dams '' t at - .•�L '^� f?$62 430 "•j
tiL ` .f
Barns Meadow Reservoir :22�22000 0 $60 $10,660
Comanche Reservoir 0 $5,800 300 $80 $11,380
Seaman Reservoir 600 $3,300 $50 $10,150
Hourglass Reservoir $2,200 $3,300 $50 $10,350
Peterson Lake Reservoi $2,200 $4,600 $3,300 $50 $10,150
Twin Lakes Reservoir 200 $4,200 $3,300 $40 $9,740
Total Project Cost $118,270
Exhibit A Exhibit B,Page 1