FLOOD03690

• County: Larimer
• Community: Wellington
• Stream Name: Boxelder Creek
• Basin: South Platte
• Title: Flood Data Boxelder Creek
• Date: 2/5/1992
• Prepared For: Larimer County
• Prepared By: CWCB
• Floodplain - Doc Type: Data ‎(general)‎

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75
20THE PURPOSE OF THIS STUDY IS TO COMPUTE FLOOD ELEVATIONS FOR 80XELDER CK
20DVERFLOW CHANNEL BETWEEN CO RO 50 (1 MILE S OF BUDWEISER BREWERY) AND
20REENTRY POINT OF O.F. CHANNEL TO MAIN CHANNEL (SHORT DISTANCE S OF HWY
2014 E OF FT COLLINS.) THE O.F. CHANNEL RUNS ALONG THE E SIDE OF 1-25. THE
20S0IL CONSERVATION SERVICE (SCS) HAD STUDIED THE MAIN & O.F. CHANNELS N
200F CO RO 50. SIMONS, LI, & ASSOCIATES, INC.(SLA) HAD STUDIED ONLY THE
20MAIN CHANNEL S OF CO RD 50. THIS STUDY WILL ALSO REDO THE MAIN CHANNEL
20(WITH ONLY ONE LOW DISCHARGE) PORTION IN THE STUDY REACH.
20SPECIFICALLY, THE PURPOSE OF THIS STUDY IS TO CONNECT SLA'S CRITERIA
20(THEIR DISCHARGES & ELEVATIONS OF THE MAIN CHANNEL AT THE REENTRY POINT)
20WITH SCS'S STARTING CRITERIA (ELEVATIONS & OISCHARGES) AT CO RO 50.
20THIS ALSO INCLUDES SEVERAL SPLITTING, COMBINING, & LOSSES OF DISCHARGES
20BECAUSE OF ARTIFICIAL BARRIERS & FLOWWAYS.
20THE SLA STUDY ORIENTATED ALL OF THEIR SECTIONS LEFT TO RIGHT WHILE
20LDOKING UPSTREAM. THIS STUDY MAINTAINS THAT ORIENTATION.
~ox5'5 10 & 21 (PART OF SLA STUDY) ARE IN THE MAIN CHANNEL & ARE KEPT THAT
20WAY FOR THIS STUOY. THE O.F. CHANNEL Q ENTERS THE MAIN CHANNEL BETWEEN
20XS'S 21 & 23.
20DISCHARGES AT THIS POINT ARE RESULT OF LDSSES FROM ROUTINGS FROM CO RD 50
20TO THIS POINT. STARTING RATING RELATING ELEVS. & QT'S WAS DERIVED FROM
20SLA OUTPUT DATA.
23XS 22 IS NOT USED; XS 23 IS KEPT INTACT IN MAIN CHANNEL AND IS
23ALSO EXTENDED LEFTWARD TO INCLUDE THE O.F. CHANNEL.
23QT-CHANGES. SPLIT BETWEEN O.F. & MAIN CHANNELS.
24A LARGE 8UILDING EXISTS ABOUT 600 FEET DWSTR FROM HWY 14. XS24 IS
24IMMEDIATELY UPSTR. FROM THE BUILDING. XS24 WAS PARTIALLY 8LOCKED OUT AS
24A NON-EFFECTIVE FLOW AREA. FLOOD WATERS FLOW AROUND THE BUILDING AND
24ELEVS. ARE HIGHER & THE FLOW PATH IS WIDER THAN COMPARED TO A
24"NO BUILDING" SITUATION.
25HWY 14.
27QT-CHANGES. SOME QT ENTERS MAIN CHANNEL TO E BETWEEN XS27 & HWY 14. SOME
27QT FLOWS OVER 1-25 AND IS LOST.COMPUTERIZEO VERTICAL EXTENSION OF
270F LT OF SECTION 27 IS O.K.: IT IS A VERTICAL SEPARATION LINE BETWEEN
270.F. CHANNEL AND FLOW OVER THE ROAD.
28QT-CHANGES: UPSTREAM FROM LOSSES AT XS 27.
28A LARGE BUILDING EXISTS ABOUT 80 FEET DOWNSTREAM FROM THE RAILROAD. XS'S
2828 & 29 ARE S & N OF THE BUILDING. RESPECTIVELY. THREE SECTIONS (28.1,
2828.2,&28.3) WERE LOCATED ACROSS THE LONG & WIDE BUILDING TO ACCURATELY
28DEFINE THE EFFECTS ON FLOW. THERE IS NO BACKWATER EFFECT ON THE RR
28EMBANKMENT SINCE IT IS FAIRLY HIGH. FLOOD WATERS FLOW AROUND THE
28BUILDING AND ELEVS. ARE HIGHER AND THE FLOW PATH IS WIDER THAN
28COMPARED TO A "NO BUILDING" SITUATION. XS 28 WAS PARTIALLY BLOCKED
280UT AS A NON-EFFECTIVE FLOW AREA; XS29 WAS NOT MODIFIED.
30RAILROAD.
311MMEDIATELY U.S, FROM R.R. QT-CHANGES. SOME QT PASSES THRU UNOERPASS
31 TO WEST AND IS LOST QT.
32QT-LOSSES. 1-25 IS LOW. WATER ACCUMULATES HERE ANO FLOWS TO WEST
32AND IS LOST.
33QT-CHANGES. UPSTREAM FROM QT LOSSES AT XS 32,
34VINE DRIVE. NO CULVERTS-ALL FLOW OVER ROAD.
34.1IMMEDIATELY U.S. FROM VINE DRIVE. 1-25 ROAD ELEVS. ARE SAME AS VINE
34.1DRIVE. THIS ALLOWS QT TO FLOW OVER 1-25 & VINE DR. AT SAME TIME.
34. 'COMPUTERIZED VERTICAL EXTENSION OF RT END DF SECTION
34.134.1 IS O.K.; IT IS A
34,1VERTICAL SEPARATION LINE 8ETWEEN O.F. CHANNEL AND FLOW OVER RD.
35QT-CHANGES. UPSTREAM FRDM LOSSES AT XS 34.1
371MMEDIATELY O.S. FROM LARIMER & WELD CANAL.
38lMMEDIATELY U.S. FROM LARIMER & WELD CANAL. QT-CHANGES. QT IN
38HWY MEDIAN ENTERS CANAL. QT IN D.F. CHANNEL ENTERS/OVERTOPS ENTIRE
38CANAL. CANAL WILL RETAIN SOME QT TO ITS ULTIMATE CAPACITY. DURING THIS

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