FLOOD10377 ‎(4)‎

• County: Weld
• Community: Fort Collins
• Stream Name: Cache La Poudre River
• Title: Volume II - Hydraulic Analysis for the Cache La Poudre River between Timnath Diversion Dam and College Ave. - Appedix G.4
• Date: 4/11/2006
• Prepared For: Fort Collins
• Prepared By: Anderson Consulting Engineers, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

EXIOOQ06.0H2

DIVIDED FLOW PATH WILL RETURN TO THE MAIN CHANNEL UPSTREAM OF THE
MULBERRY BRIDGE. THIS PROVIDES A MORE AUTOMATED AND CONSERVATIVE
MODEL.
5. DELETED ALL OF THE 500-YEAR DISCHARGE INPUT FROM ALL QT CARDS FROM THE
EFFECTIVE LOWER Q 100-, 50-, AND 10-YEAR FLOODPLAIN MODEL (LOWQ99.DAT)
SINCE 500-YEAR WATER SURFACE ELEVATIONS WERE NOT COMPUTED UTILIZING;
THIS CORRECTED EFFECTIVE MODEL.
6. TRUNCATED THE LEFT OVERBANK GEOMETRY FROM THE GEOMETRY DATA OF II
CROSS SECTIONS 228117, 229322, AND 229477 DUE TO THESE AREAS
NOT BEING HYDRAULICALLY CONNECTED TO THE MAIN CHANNEL.
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FILE: RCUPR05.DAT
THIS 2005 REMOVAL ACTION LOMR REVISED CONDITION MODEL:
9. INCORPORATES AS-BUILT TOPOGRAPHY FOR THE REMOVAL ACTION
SITE THE 1-FT AS-BUILT TOPOGRAPHY FOR THE REMOVAL ACTION
SITE WAS DEVELOPED FROM POST-PROJECT LAND SURVEYS CONDUCTED BY
BY NORTHERN ENGINEERING IN JUNE 2005. GEOMETRY FOR THE
FOLLOWING CROSS SECTIONS WERE UPDATED UTILIZING THE AS-
BUILT SURVEY TOPOGRAPHY WERE APPROPRIATE; 229322, 229477, 1
AND 229757. I
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FILE: CEUPR05.DAT
THIS 2005 REMOVAL ACTION LOMR CORRECTED EFFECTIVE MODEL:
1. IS BASED ON THE REVISED CONDITION MODEL UPPER-RC.DAT
FROM THE POWER PLANT DROP STRUCTURE/BOAT CHUTE LOMR
CONDUCTED IN 2001. THE 2001 POWER PLANT DROP STRUCTURE/BOAT CHUTE
LOMR REVISED THE 1994 UPPER.DAT FEMA MODEL BY ADDING TWO CROSS
SECTIONS (230193 AND 230355) TO REFLECT THE NEW GRADING ASSOCIATED
WITH THE DROP STRUCTURE.
2. COMPUTES 100-, 50-, AND 10-YEAR WATER SURFACE PROFILES FOR THE
MAIN CHANNEL. DISCHARGES UTILIZED TO COMPUTE THE WATER SURFACE
PROFILES ARE BASED ON THE SPLIT FLOW DISCHARGES DETERMINED FROM
THE 1994 UPPERQ.DAT MODEL.

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STRUCTURE/BOAT CHUTE LOMR

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SECTION 230355.
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LOMR.
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FILE: LOWQ99.DAT
THIS 1999 LOMR MODEL: I
1. IS BASED ON THE 1997 LOWQ97R.DAT MODEL.
2. INCORPORATES AS-BLT SURVEY DATA BETWEEN X-SEC.S 212317 THRU 216105 I

P:\COFC2003\1O - Oxbow Levee\LOMR\FinDisk (Final)\Appendix G\FEMA Mod~ls\Existing Models\EXIOOQ06.doc

3. CHANGED THE STARTING WATER SURFACE ELEVATIONS FOR ALL PROFILES I
TO MATCH THE OUTPUT OF THE EFFECTIVE LOWER 100-, 50-, AND 10-YEAR '
FLOODPLAIN MODEL FROM THE 1999 TIMBERLINE ROAD LOMR LOMR (LOWQ99.DAT,).
4. INCORPORATES UPDATED PRE-PROJECT TOPOGRAPHY BETWEEN THE
DOWNSTREAM SIDE OF LINDEN STREET, CROSS SECTION 228637, AND JUST
DOWNSTREAM OF THE B.N.R.R., CROSS SECTION 229997. TWO SETS OF
TOPOGRAPHY WERE UTILIZED TO UPDATE THE HYDRAULIC MODEL. 1-FT PRE-
PROJECT TOPOGRAPHY FOR THE REMOVAL ACTION SITE WAS DEVELOPED FROM
LAND SURVEYS CONDUCTED BY NORTHERN ENGINEERING IN 2004. PRE-PROJECT
TOPOGRAPHY FOR PORTIONS OF THE LEFT OVERBANK THAT WERE NOT
INCLUDED IN THE TOPOGRAPHY DEVELOPED FOR THE REMOVAL ACTION SITE
WERE OBTAINED FROM THE COFC. THE COFC 2-FT TOPOGRAPHY WAS DEVELOPED
FROM AERIAL PHOTOS TAKEN IN 1999. GEOMETRY FOR THE FOLLOWING
EFFECTIVE CROSS SECTIONS WERE UPDATED UTILIZING THE PRE-PROJECT
TOPOGRAPHY; 228637, 228687, AND 229477. WHILE UPDATING THE
GEOMETRY FOR CROSS SECTION 229477 IT WAS DECIDED TO SHORTEN THE
GR DATA FOR THE RIGHT OVERBANK. THUS, CROSS SECTION 229477
WAS SHORTENED BY APPROXIMATELY 800 FEET.
5. INCLUDES THE ADDITION OF TWO CROSS SECTIONS AT THE DOWNSTREAM
(229322) AND-THE .UPSTREAM- (229757) ENDS OF THE REMOVAL ACTION
PROJECT SITE. PRE-PROJECT TOPOGRAPHY WAS UTILIZED TO DEVELOP THE
GEOMETRY FOR CROSS SECTIONS 229322 AND 229757.
6. CHANGED THE X3 CARD FOR CROSS SECTION 229477 INTO AN ET CARD AND
ADJUSTED THE LEFT ENCROACHMENT STATION OF 6770 ON THE X3 CARD TO
STATION 7165 ON THE ET CARD TO REPRESENT THE INEFFECTIVE FLOW IN
THE LEFT OVERBANK CAUSED BY BUILDINGS UNDER CONSTRUCTION IN THE
EFFECTIVE CONDITION PHOTO (IMPACTS 500-YEAR FLOWS ONLY).
7. CHANGED THE LEFT ENCROACHMENT STATION OF THE X3 CARD FOR CROSS
SECTION 229997 FROM STATION 8170 TO STATION 8170.1 SO THAT
THE ENCROACHMENT STATION WOULD LIE WITHIN THE GEOMETRY DATA.
8. HAS A -1 INSERTED INTO FIELD 7 OF THE J2 CARD TO COMPUTE
CRITICAL DEPTH AT ALL CROSS SECTIONS.

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Created on 3/9/2006 3:42 PM