SCOPE OF WORK
CONTRACT ________________
DECEPTION GULCH FLOODPLAIN DELINEATION STUDY
GENERAL
The purpose of this project is to restudy the Deception Gulch watershed identified to drain to the
Verde River and prepare detailed delineation for an estimated 3.5 miles of watercourse. The
delineations are to be based on the two-foot contour interval mapping supplied by the Yavapai
County Flood Control District (DISTRICT) plus additional field survey as described. The
detailed floodplain delineations, as well as hydrologic analysis, shall be used as a regulatory tool
by the DISTRICT.
The study area is located primarily within the incorporated area of Clarkdale, Arizona, with the
upper portion falling in the unincorporated portion of Yavapai County (Exhibit 1). State
Highway 89A passes through the study area and crosses Deception Gulch within Clarkdale. The
watershed extends southwesterly into the Woodchute Mountain area of the Prescott National
Forest.
All work shall meet Arizona Department of Water Resources (ADWR) and Federal Emergency
Management Agency (FEMA) requirements for floodplain delineations. Prior to the finalization
of this contract, FEMA and the DISTRICT must review and accept the results of this study, and
all items called for in this Scope of Work must be delivered to the DISTRICT. The
CONSULTANT will submit the study to FEMA for review and approval.
The Consultant shall complete the project within 240 days from the Notice to Proceed (NTP) for
submittal to FEMA for its review and approval. This includes 30 days for DISTRICT reviews.
The following tasks shall be performed by LTM Engineering, Inc. (CONSULTANT)
TASK 1: RECONAISSANCE, DATA COLLECTION, AND COORDINATION
CONSULTANT shall identify a single point-of-contact (Project Manager) for duration of the
contract. The Project Manager shall be responsible for coordination with the DISTRICT and any
additional contacts necessary during the course of the project. The Project Manager shall
participate in all coordination meetings.
1.1 CONSULTANT shall conduct a detailed field reconnaissance of the study area to determine
watershed characteristic conditions along the floodplains, types and numbers of hydraulic
structures, and locations of cross sections or areas to be surveyed for use in hydrologic and
hydraulic analyses.
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Field reconnaissance visits shall be documented in the appropriate technical portions of the
Technical Data Notebook (TDN). A data collection summary report will be prepared
included in Appendix A of the TDN.
CONSULTANT shall make reasonable attempts to collect and review available pertinent
data such as the drainage design reports and grading, drainage, and paving plans available
from the Arizona Department of Transportation (ADOT), as well as from FEMA, the
DISTRICT, and any local communities. CONSULTANT shall prepare a list summarizing
the collected data for inclusion in the study report.
1.2 This task shall also include coordination, communication, and research to comply with
FEMA standards. Of particular importance is the need for (1) coordination in verifying
topographic data and requirements for additional field survey, (2) communication of
intermediate and final study results, and (3) research of existing data.
1.3 CONSULTANT shall prepare and maintain a project schedule and shall schedule and attend
a kick-off meeting and two (2) subsequent coordination/progress meetings. CONSULTANT
shall prepare meeting minutes, progress reports, and billings.
1.4 The DISTRICT shall be responsible for placing a legal advertisement at the beginning of the
study. The advertisement will be run twice, one week apart, in a widely circulated
newspaper. Also, if a local newspaper serves the area being studied, the DISTRICT will also
place an advertisement, to run twice, in the local newspaper. After the ads are run, the
DISTRICT will supply the CONSULTANT with the original affidavit of publication from
each newspaper for each day that the ads ran. to CONSULTANT for inclusion in the TDN.
TASK 2: FIELD SURVEYS AND TOPOGRAPHIC DATA VERIFICATION
Survey information for this project will be referenced horizontally to the North American Datum
of 1983(National Spatial Reference System of 2007 epoch) (NAD83 (NSRS2007)) and vertically
to the North American Vertical Datum of 1988 (NAVD 88) with an equation provided for
conversion to the National Geodetic Vertical Datum of 1929 (NGVD29). Map projection for this
project shall be the State Plane Coordinate System of 1983, Arizona Central (zone number
0202). Yavapai County will provide 2 foot contour interval topographic mapping for the project
area. The topographic mapping supplied by Yavapai County is certified to be to FEMA
standards. Linear units shall be in International Feet.
Specific tasks for survey field work are as follows:
2.1 CONSULTANT shall be responsible for obtaining right-of-entry for surveying and field
investigations necessary during the course of the Deception Gulch Flood Hazard Study.
2.2 PROJECT COORDINATION - CONSULTANT shall coordinate with the study team and
the Town of Clarkdale as necessary throughout the project.
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2.3 RESEARCH - CONSULTANT shall research existing record mapping from NGS, FEMA,
and ADOT as necessary to perform the survey tasks.
2.4 SURVEY CONTROL - CONSULTANT shall locate field monumentation as necessary to
establish horizontal and vertical control within the project limits and analyze and adjust the
project control as located from the survey control field work.
2.5 BRIDGE TOPOGRAPHIC SURVEY FIELD WORK - CONSULTANT shall locate the
horizontal and vertical position of the existing bridge structures (piers, abutments, bridge
deck, and bottom of bridge support members). CONSULTANT shall prepare field sketches
and take pictures of existing bridges.
2.6 TOPOGRAPHIC SURVEY ROADWAY CROSSINGS – For other crossings such as dip
sections and culvert crossings CONSULTANT shall include topographic survey field work
to locate the centerline of the road or trail at 50 foot intervals within 500 feet of the dip
sections and culvert crossings. CONSULTANT shall identify culvert invert elevations,
locations, pipe size(s) and type. CONSULTANT shall, if possible, note the condition and
take pictures of the crossing.
2.7 TOPOGRAPHIC SURVEY – CONSULTANT shall provide additional cross sections of
Deception Gulch as necessary to augment the topography provided. Cross section locations
shall be determined by the CONSULTANT.
2.8 SURVEY BENCH MARKS - CONSULTANT shall establish four Bench Marks within the
project limits. The bench marks shall be set with Yavapai County Aluminum caps
(provided) within one mile of Deception Gulch.
2.9 SURVEY REPORT - Survey Report: CONSULTANT shall prepare a report summarizing
the results and methodology of the survey tasks associated with this project.
TASK 3: HYDROLOGIC ANALYSES
The extent of the hydrologic effort will depend on the applicability of prior analyses conducted
by others.
3.1 HYDROLOGIC REVIEW - CONSULTANT shall research and evaluate existing hydrologic
data and determine their usability by three methods:

USGS regression equations as presented in ADWR’s State Standard 2-96 and associated
envelope curves

Comparison of unit peak discharges (cfs/square mile) with similar watersheds

Comparison with historical data (USGS stream gage 09504000 at the Verde River and
Sycamore Canyon)
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CONSULTANT shall prepare a technical memorandum and recommend a course of action.
Regardless of whether or not a new analysis is warranted, the analysis will be incorporated into
the TDN as part the validation of hydrology.
If the DISTRICT and CONSULTANT concur that new hydrologic modeling is appropriate,
HEC-1 will be used to develop new peak discharges as described in the remaining hydrologic
subtasks.
The following optional subtasks are not authorized with the Notice to Proceed; they may be
authorized in writing by the DISTRICT based upon specific need as determined by the
DISTRICT based upon the results of Task 3.1.
3.2
CONSULTANT shall use the U.S. Army Corps of Engineers computer program HEC-1 to develop
a hydrologic model for the area. The peak discharges for the 100-year and 500-year 6-hour and 24hour storms will be developed based on NOAA Atlas 14 precipitation data. All calculations, or
assumptions used in developing sub-basin and routing parameters shall be documented and made a
part of the appendix for the hydrology report. Output of the computer model shall be reviewed
to determine if the peak flows and volumes are reasonable and realistic.
3.3
The sub-basin delineation shall be based on detailed topography provided for the study,
USGS topographic mapping, aerial photograph and field visits. Sub-basin delineation shall
be refined to provide concentration points at roadway crossings and other critical points for
this study throughout the watershed. If GIS-based modeling is used, CONSULTANT shall
document automated data processing and modeling algorithms and provide them to FEMA
to ensure they are consistent with the required standards.
3.4
The CONSULTANT will conduct a field reconnaissance of the full study area. This will
include observation of watershed and floodplain conditions; photographic documentation
of floodplain characteristics; observation of land use and street intersections; determination
of channel bank stations; observation of possible overflow areas; and measurement of
culvert dimensions. This data submission may also discuss floodplain conditions affecting
the delineation, describe structures and obstructions, and provide color photos or
photocopies of major hydraulic structures. The input parameters and the results shall be
documented in the TDN.
The CONSULTANT shall clearly identify and incorporate appropriate comments in the
hydrologic model regarding diverted flows and any other features of the model that merit
explanation.
3.5
3.6
The findings of the hydrologic study will be presented in Section 3 of the TDN. All
calculations, or assumptions used in developing sub-basin and routing parameters shall be
documented and made a part of the appendix for the hydrologic report. Additionally, all
FEMA-compliant hydrologic exhibits shall be included.
TASK 4: HYDRAULIC ANALYSIS
4.1 CONSULTANT shall prepare detailed hydraulic models for approximately 3.5 miles of the
Deception Gulch watercourse in the study area as shown in Exhibit 2. The modeling shall
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include the 1 and 0.2-percent-annual-chance (100 and 500 year) events based on peak
discharges computed in Task 3. CONSULTANT shall prepare the study using Yavapai
County requirements and the guidelines established in FEMA’s Guidelines and
Specifications for Flood Hazard Mapping Partners, April 2003.
CONSULTANT shall provide the DISTRICT review submittals at each of the following
steps:
a.
Draft field reconnaissance section of the TDN and estimation of Manning's "n"
values.
b.
Proposed location and alignment of the cross sections.
c.
Approximate floodplain delineation.
4.2 CONSULTANT shall use the topographic mapping and DEM provided by Yavapai County
to perform the hydraulic analyses. The floodplain/floodway delineations shall be used to
establish flood elevations and regulatory floodways for the Deception Gulch flooding
sources. The delineation work shall meet requirements for floodplain delineations as
prescribed by FEMA and the Arizona Department of Water Resources. The mapping scale
shall be 200’ per inch or as approved by the DISTRICT. The hydraulic modeling and
delineation work maps shall be in the North American Vertical Datum of 1988 (NAVD 88).
4.3 Field Reconnaissance
4.3.1
CONSULTANT shall conduct a field reconnaissance of the study area. This will
include observation of channel and floodplain conditions for estimating
Manning's "n" values; photographic documentation of floodplain characteristics;
determination of channel bank characteristics; observation of possible overflow
areas; observation of levees or other structures in the floodplain.
4.3.2
Manning’s "n" values are to be determined using the methodology in the USGS
report, Estimated Manning's Roughness Coefficients for Stream Channels and
Flood Plains in Maricopa County, Arizona, April 1991 or Roughness
Characteristics of Natural Channel, Geological Survey Water-Supply Paper 1849
as appropriate. Manning’s Roughness Coefficients will be presented for typical
reach types observed in the project area.
4.3.3
Representative “n” values for each typical reach type will be selected. The
reconnaissance report will present the determination of channel and over bank "n"
values using captioned color photographs or color photocopies for each identified
reach type in the project area, and the extents of the typical reach types shall be
displayed on an aerial photo exhibit. The report will also discuss floodplain
conditions affecting the delineation, describe structures and obstructions, and
provide color photos or photocopies of major hydraulic structures. Photo locations
for channels, structures, and "n" value determinations will be displayed on
reduced scale mapping and included in the final report
4.4 Cross Sections
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4.4.1
CONSULTANT shall develop cross sections for the study watercourses. Cross
section placement locations shall be selected with respect to existing structures
such as roads, railways, drainage features, and confluences. Cross section spacing
shall be approximately 400 feet and done in such a way as to minimize
computational head losses and where natural grade breaks occur as defined by
thalweg profile plots. Cross sections may require closer spacing when necessary
to properly model this variable floodplain. Cross section stationing will be from
left to right looking downstream. Identification of cross sections will be in river
miles, increasing upstream from the confluence with major drainages. The
stationing will begin at the downstream end of Deception Gulch at the Verde
River. The cross sections may need to be re-oriented or altered after running the
HEC-RAS model to ensure that they are perpendicular to flow per FEMA criteria.
Cross sections developed by the HEC-RAS interpolation feature are not to be
used.
4.5 Floodplain Delineation/HEC-RAS Modeling
4.5.1
CONSULTANT shall delineate the 1- and 0.2-percent-annual-chance (100 and
500 year) floodplain boundaries and the regulatory floodway boundaries for the
flooding sources for which detailed hydrologic and hydraulic analyses were
performed. CONSULTANT shall prepare detailed floodplain delineation for
approximately 3.5 miles of the Deception Gulch watercourse in the study area.
The study methods are to be per FEMA guidelines. Refer to Exhibit 2 for the
identification of the study limits for the detailed floodplain delineations.
4.5.2
CONSULTANT will develop a HEC-RAS model and delineate approximately 3.5
miles of Zone AE (or appropriate zone designation) floodplain with floodway
based upon the final results of the hydrologic study from Task 3 and as directed
by the DISTRICT.
Floodways are to be determined using method 4 or 5 with equal conveyance
encroachment to start with, but only encroachment method 1 will be used in the
final analysis. The floodway encroachment should produce a rise in the water
surface elevation that is as near the one-foot maximum as possible.
4.5.3
The hydraulic effects of bridges and culverts shall be incorporated into the
assessment of the floodplain around such structures. The Zone AE limits must be
determined according to FEMA criteria and clearly labeled on the final drawings.
Minor conveyance structures such as small culverts (i.e., less than 30” in
diameter) or structures considered likely to become clogged during the 100-year
peak discharge shall not be included in the hydraulic analyses. Floodplain may be
required to be assessed for elevated structures using the “with and without”
scenarios. In these cases the existing conditions model will serve as the “with”
structure model. For the “without” structure model the topography will be
modified to removed the elevated structures.
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4.5.4
For flow splits or other complex hydraulic situations, other modeling techniques
such as hand calculations using culvert, weir or orifice equations shall be used as
needed to properly characterize the flow.
4.5.5
CONSULTANT and the DISTRICT shall conduct a field trip to review the results
of the Floodplain Delineations.
4.5.6
The main project description box of the HEC-RAS models should include the
following:
a. Project Name and Contract Number
b. Consultant(s) and Modeler's Name(s)
c. File Name and latest run date/final date if completed
d. Vertical Datum of the model, base map date, and base map contractor
information
e. Source of the peak discharges used in the hydraulic analysis
In addition, minor descriptions should be added to the model for hydraulic
sections located above and below drainage structures, at major transportation
crossings, and at confluences. Model descriptions should be added for culverts
and lateral structures, and at any other feature considered more important or
unique to the modeling.
4.5.7
CONSULTANT shall review the output of the HEC-RAS computer model to
ensure the flow depths and velocities are reasonable and realistic with those
expected in this watershed. The use of separate modeling software such as
FlowMaster may be used for this review.
4.6 CONSULTANT shall provide work maps on base mapping provided by the DISTRICT.
The work map drawings will be 24" X 36" in size. The work map scale shall be 1”=200’ or
as directed by the DISTRICT. Flood Zones must be determined according to FEMA criteria
and clearly labeled on the work maps.
A cover sheet will be part of the work-study drawings and shall include the project title,
source and date of topographic mapping, and a location map showing geographic range
covered by each specific mapping sheet. Each drawing will include the watercourse names
and floodplain boundaries, floodway boundaries, a north arrow, scale, section corners,
current streets and highway names, Horizontal and Vertical Datum references (State Plane
Coordinate System, NAD 83, and NAVD 88), any DISTRICT monument labels located
within individual sheet boundaries, major drainage features, corporate boundaries, hydraulic
cross section lines, channel station centerline, index map, base flood elevations (BFE),
floodway delineation, peak discharges at selected locations, and Section, Township, Range
for each watercourse delineated.
4.7
Technical Data Notebook
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4.7.1 The findings of the floodplain delineation study will be presented in Section 5 of the
TDN and will be prepared in accordance with ADWR State Standards Attachment 197 (SSA 1-97). The report will be organized as specified by the DISTRICT
standards, following SSA 1-97 format.
4.7.2 The Hydraulic analysis/HEC-RAS output of the TDN, in addition to summary tables
and output report, should include fully labeled cross section plots. Section plots
should be grouped per study reach, and reach groups should be separated and then
indexed within the main report to expedite data recovery.
4.8 CONSULTANT shall complete all the forms required by FEMA for the submittal of a
Floodplain Delineation Study.
TASK 5: FLOODPLAIN MAPPING
CONSULTANT shall delineate the 1- and 0.2-percent-annual-chance (100- and 500-year)
floodplain boundaries and the regulatory floodway boundaries for the flooding sources for which
detailed hydrologic and hydraulic analyses were performed. CONSULTANT shall prepare
detailed floodplain delineation for approximately 3.5 miles of the Deception Gulch watercourse
in the study area. Refer to Exhibit __ for the identification of the study limits for the detailed
floodplain delineations.
TASK 6: DELIVERABLES
Project documentation shall be compiled along with the data in the TDN. The TDN shall be
prepared in accordance with the ADWR State standard 1-97. The study shall be submitted to the
DISTRICT for review and signature on the Community Concurrence Form. Upon acceptance by
Yavapai County, CONSULTANT shall submit the TDN to FEMA for its review.
CONSULTANT shall provide additional information requested and coordinate with FEMA as
need for study acceptance. Deliverables shall be submitted as follows:
6.1 Prior to FEMA Submittal: CONSULTANT will deliver the following items to the
DISTRICT for review and approval:
6.1.1 One (1) copy of the draft TDN, including completed FEMA forms, annotated Flood
Insurance Rate Maps, HEC-1 (if used) and HEC-RAS model results (on CDs).
6.1.2 If bound separately from the TDN, one copy of the field survey notes and office
calculations and electronic survey data.
6.1.3 One (1) set of work maps with floodplain delineations.
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6.1.4 One (1) set of the explanation for unresolved messages from the CHECK-RAS as
appropriate.
6.1.5 For GIS-based modeling, deliverables include all input and output data,
intermediated data processing products, GIS data layers, shape files, and/or geodatabases
6.2 FEMA Submittal: CONSULTANT will submit the following items to the DISTRICT and
FEMA for review and approval:
6.2.1 One (1) complete set of work maps with the floodplain delineations shown. All
drawings will be signed and sealed by persons of appropriate professional
registration(s). Each registrant will provide a specific statement as to what service
(s)he performed.
6.2.2 One (1) complete copy of the TDN, including completed FEMA forms, annotated
Flood Insurance Rate Maps showing the proposed delineation, HEC-1, and HECRAS input/output files on diskettes. The notebook will be organized as specified by
the DISTRICT, following SSA 1-97 format.
6.3 Final Submittal: The following products are the deliverables for the final submittal to the
DISTRICT after FEMA approval is issued:
6.3.1 One (1) complete set of Mylars and five complete sets of sealed work maps with the
floodplain/floodway delineations shown. All drawings will be signed and sealed by
persons of appropriate professional registration(s). Each registrant will provide a
specific statement as to what service they performed.
6.3.2 All hydrologic and floodplain delineation data in conformance with the contract
specifications which include Digital work maps showing the 1- and 0.2-percentannual-chance floodplain boundary delineations, regulatory floodway and Digital
boundary delineations, cross sections, BFEs, flood insurance risk zone labels and
applicable base map features
6.3.3 Five complete bound copies of the TDN including HEC-1 input/output files on
diskettes. The TDN shall include any correspondence and/or meeting minutes with
the reviewing agencies and shall reflect any revisions required by those reviewing
agencies. Revisions may include, but are not limited to, addressing FEMA's
comments, modifications to the delineation maps, the HEC-1 model, and/or the Final
Report.
6.3.4 One (1) electronic copy of the TDN report on CD as pdf files.
6.3.5 For GIS-based modeling, deliverables include all input and output data,
intermediated data processing products, GIS data layers, shape files, and/or geodatabases.
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TASK 7: PUBLIC MEETING
7.1 CONSULTANT shall attend an open-house style public meeting. The public meeting will be
coordinated by the DISTRICT. CONSULTANT shall provide a copy of the floodplain
delineation work maps and prepare one exhibit for the public meeting. The CONSULTANT
Project Manager shall attend the public meeting to talk with concerned residents and answer
general questions.
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