FLOOD10336 ‎(2)‎

• County: Adams
• Community: Brighton, Commerce City and Thornton
• Stream Name: South Platte River
• Title: Flood Hazard Area Delineation, South Platte River, Adams County
• Date: 4/1/2005
• Prepared For: UDFCD; Adams County; Brighton, Commerce City, Thornton, Metro Wastewater
• Prepared By: CDM
• Floodplain - Doc Type: Floodplain Report/Masterplan

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061

CDIVI

,40892\PREP~FHAD\S 1.DOC

415/05 cje

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Vertical control is in Us. feet, based on National Geodetric Reference System first order marks, North American
Vertical Datum (NA VO) 1988 datum. Elevation of the project grid is 5,000 feet-mean sea level (msl). The mapping
was prepared at a contour interval of 2 feet at a scale of 1:1,200 and conforms to National Map Accuracy Standards
(NAMAS).

South Adams County Water and Sanitation District

Mr.

Mr. Bob Neal
Mr. John Van Royen
Ms. Barbara Biggs

Greg Fabisiak

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Northing State Plane Value/Combined Project Factor -1,000,000
Easting State Plane Value/Combined Project Factor - 3,000,000
The Combined Project Factor equals 0.99979199

MWRO

Ms.
Mr.
Mr. Neil

Sperandeo

Jessica Barbier
Norm Carlson

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Mapping for this project is based on aerial photography obtained by Adams County, UOPCD, and Metro
Wastewater Reclamation District (MWRD) in 1995 and updated in 1998. Base map horizontal control is based on
the Colorado High Accuracy Reference Network (HARN), NAD 83-92 Modified State Plane U.s. feet, Colorado
Central Zone (502). Modified coordinate system is:

Denver

City of Thornton

Water

Mr. Frank Casteleneto
Ms. Diane Van Fossen

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Mr.
Mr.
Mr.

Daren Sterling

Neil Goodenough
Tom Acre

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1.4 Mapping

City of Commerce City

. Preparation of

. Analyze floodways based on encroachments resulting in maximum increase in the energy grade line of 0.5 foot
and 1.0 foot

water surface profiles and delineation of 100- and 500-year floodplain boundaries

City of Brighton

Mr.
Mr.
Mr.

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. Identify and incorporate Letters of Map Revision (LOMR) and other changes to the river sustained since the
development of the Master Plan Update hydraulic modeling

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. Convert hydraulic modeling from the 2002 South Platte River in Adams County Master Plan Update (Camp
Dresser & McKee Iue. rCDM] 2000) HEC-2 program to HEC-RAS version 3.1.1

Mr.
Ms.
Mr.
Mr.
Ms.
Mr.

Tony Huerta
Marvin Palconburg
Mark Heidt

Crystal Gray
Rick Anderson
Marc Pedrucci
Nicki Stoner
Craig Tessmer

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Adams County

Besharah Najjar

Mr. Bill DeGroot
Mr. Ben U rbonas
Mr. Bryan Kohlenberg

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. Meet

The scope of work for this study includes the preparation of a Flood Hazard Area Delineation Report (FHAD) and
associated hydraulic calculations and mapping. Specific tasks itemized in the Agreement include:

periodically with representatives from

the UDFCD and local sponsors

UDPCD

Organization

Contributor

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1.3 Scope of Work

COM would
this study:

The purpose of this study is to provide local jurisdictions
floodplains and flood ways through Adams County, Colorado,
and safety.

with a basis for management of the South Platte River
minimizing threats from flooding to public health

like to acknowledge the following contributors who provided data and information used to complete

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1.2 Purpose

This study was authorized by the Urban Drainage and Flood Control District
03-07.01, dated October 28, 2003.

1.6 Acknowledgements

Background information relevant to this study was obtained from the South Platte River in Adams County Major
Orainageway Planning Phase A and Phase B Reports, produced by CDM for the UOFCD in June 2000 and
April 2002, respectively (UOFCD 2000; UOPCD 2002). These documents are referred to in this report as the
Master Plan.

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1.1 Authorization

(UOFCD) under

Agreement

No.

1.5 Background Information

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Section 1
Introduction

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4/8/05