HomeMy WebLinkAboutDrainage Reports - 12/15/1995 (2)Fi al p pproved Wo 11
FINAL DRAINAGE AND
EROSION CONTROL STUDY
FOR BLOCKBUSTER EXPANSION
AT CMARRON PLAZA
FORT COLLINS, COLORADO
FINAL DRAINAGE AND
EROSION CONTROL STUDY
FOR BLOCKBUSTER EXPANSION
AT CIMARRON PLAZA
FORT COLLINS, COLORADO
November 8, 1995
Prepared for:
Cimarron, Ltd.
7854 S-, Argonne
Aurora, Colorado 80016
Prepared by:
RBD, Inc. Engineering Consultants
209 South Meldrum
Fort Collins, Colorado 80521
(30-3) 482-5922
RBD Job No. 108-0I I
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INC.
Engineering Consultants
209 S. Meldrum
Fort Collins, Colorado 80521
303/482-5922
FAX: 303/482-6368
November 8, 1995
Mr. Glen Schlueter
City of Fort Collins
Utility Services Stormwater
235 Mathews Street
Fort Collins, Colorado 80522
RE: Final Drainage and Erosion Control Study
Blockbuster Expansion at Cimarron Plaza
Dear Glen:
We are pleased to submit to you, for your review and approval, this revised Final Drainage and
Erosion Control Study for the Blockbuster Expansion at Cimarron Plaza. All computations
within this report have been completed in compliance with the City of Fort Collins Storm
Drainage Design Criteria.
We appreciate your time and consideration in reviewing this submittal. Please call if you have
any questions.
Respectfully,
RBD Inc. Engineering Consultants
Prepared by:
-5(�-� 4�
David K. Thaemert,
Water Resources Enj
cc: Mr. David Faestel
Reviewed by:
Kevin W. Gingery, P.
Water Resources Project Manager
Denver 303/458-5526
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TABLE OF CONTENTS
DESCRIPTION PAGE
I.
GENERAL LOCATION AND DESCRIPTION
1
A. Location
1•
B. Description of Property
1
II.
DRAINAGE BASINS
1
A. Major Basin Description
1
III.
DRAINAGE DESIGN CRITERIA
1
A. Regulations
1
B. Development Criteria Reference and Constraints
2
C. Hydrological Criteria
2
D. Hydraulic Criteria
2
E. Variances from Criteria
2
IV.
DRAINAGE FACILITY DESIGN
2
A. General Concept
2
B. Specific Details
2
V.
EROSION CONTROL
3
A. General Concept
3
B. Specific Details
3
VI.
CONCLUSIONS
3
A. Compliance with Standards
3
B. Drainage Concept
4
C. Erosion Control Concepts
4
REFERENCES
4
APPENDIX
VICINITY MAP 2
EXPANSION HYDROLOGY AND DETENTION 3
EROSION CONTROL 14
Total pages 20
' FINAL DRAINAGE AND
EROSION CONTROL STUDY
' FOR BLOCKBUSTER EXPANSION
AT CIMARRON PLAZA
FORT COLLINS, COLORADO
I. GENERAL LOCATION AND DESCRIPTION
' A. Location
The Blockbuster Expansion at Cimarron Plaza is located within the existing
' Cimarron Plaza on the southwest corner of Drake Road and Shields Street.
Specifically, the expansion is an enlargement of the Blockbuster Video retail store
located along the eastern edge of Cimarron Plaza.
' The site location can also be described as situated in the Northeast '/a of Section
27, Township 7 North, Range 69 West of the 6th P.M., City of Fort Collins,
' Larimer County, Colorado. The site Iocation can be seen on Exhibit 1 in the
Appendix.
' B. Description of Property
The site currently contains a Blockbuster Video building, described as Building
y' E on previous plans and reports. The ground available for expansion lies on the
south side of the existing building and contains a grassed area. The tract of land
contains approximately 0.48 acres. The expansion is bounded by the existing
building on the north, grassed margins to the south and east, and the existing
parking lot to the west.
' II. DRAINAGE BASINS
A. Major Basin Description
The proposed expansion lies within the Spring Creek drainage basin. According
' to the report titled "Cimarron Plaza P.U.D. Final Drainage Report," dated
September 5, 1985, by RBD, Inc., stormwater discharge in this basin is limited
to the 2-year historic flow.
1 III. DRAINAGE DESIGN CRITERIA
' A. Regulations
The City of Fort Collins Storm Drainage Design Criteria is being used for the
' subject site.
IB. Development Criteria Reference and Constraints
' According to the report titled "Cimarron Plaza P.U.D. Final Drainage Report,"
dated September 5, 1985, by RBD, Inc., the Blockbuster expansion lies within
Basin A as shown on the Grading and Drainage Plan in the back pocket of this
' report. The expansion is required to direct developed stormwater runoff west into
the existing Cimarron Plaza parking lot detention area. Detention is required as
the site is limited to discharging the 2-year historic runoff.
' C. Hydrological Criteria
The Rational Method for determining surface runoff was previously used for the
project site. The 2-year and 100-year storm event criteria, obtained by the City
of Fort Collins, were previously used in calculating runoff values. These
previous calculations and criteria are included in the Appendix of this report.
D. Hydraulic Criteria
All hydraulic calculations within this report have been prepared in accordance
with the City of Fort Collins Drainage Criteria and are also included in the
Appendix.
E. Variances from Criteria
No variances are being sought for the proposed project site.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
The Blockbuster Expansion is intended to develop in accordance with the
' previously -approved P.U.D. plans for the existing Cimarron Plaza. Included in
the back pocket of this report are drawings from the previously -approved project
for reference to this current project. Revisions have been made to each of these
' drawings, as allowed by the City of Fort Collins Stormwater Utility, to address
the proposed building expansion.
1
B. Specific Details
The Blockbuster Expansion will encompass the area adjacent to (south of) the
existing Blockbuster Video building at Cimarron Plaza. Once completed, the
proposed building will abut the existing building. Runoff from the expansion will
be directed to the existing parking lot detention area to the west of the building.
FA
The existing detention pond and outlet mechanism within Basin A was previously
sized and constructed large enough to accommodate the building expansion as
shown in the appendix of this report. Therefore no modifications to any of the
existing detention pond improvements are necessary with for the Blockbuster
Expansion.
V. EROSION CONTROL
A. General Concept
This development lies within the Moderate Rainfall Erodibility Zone and the
Moderate Wind Erodibility Zone per the City of Fort Collins zone maps. It is
anticipated that the project site improvements will be subject to minor erosion
before the building is constructed.
The Erosion Control Performance Standard (PS) after construction for this project
was computed to be 92.2 percent per the criteria in the City of Fort Collins
Erosion Control Reference Manual for Construction Sites. The Effectiveness
(EFF) of the proposed erosion control plan was calculated to be 99.0 percent.
Therefore, the erosion control plan below meets the City of Fort Collins'
requirements. A copy of the calculations has been included in the Appendix. An
erosion control escrow cost estimate of $1,000 is also included in the Erosion
Control section of the Appendix.
B. Specific Details
Before construction of the Blockbuster Expansion, install silt fence around the
perimeter of the site as shown on the grading and drainage plan in the back of
this report. The erosion control measures shall remain in place and in effect until
the building infrastructure has been completed and remaining exposed ground has
been sodded.
VI. CONCLUSIONS
' A. Compliance with Standards
All computations that have been completed within this report are in compliance
with the City of Fort Collins Erosion Control Reference Manual for Construction
Sites and the Storm Drainage Design Criteria Manual. In addition, all
computations are in compliance with the 1985 "Cimarron Plaza P.U.D. Final
' Drainage Report" and 1990 "Cimarron Plaza P.U.D. - Drive Thru Along Giant
Video," both prepared by RBD, Inc.
3
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B. Drainage Concept
The proposed drainage concepts adequately provide for the transmission of
developed on -site runoff to the existing drainage facilities within the Cimarron
Plaza site. All building expansion stormwater runoff will be directed into the
existing detention pond located within the parking lot of the existing Cimarron
Plaza.
If for some unforeseen reason groundwater is encountered at the time of
construction, a Colorado Department of Health Construction Dewatering Permit
would be required.
C. Erosion Control Concepts
The proposed erosion control concepts adequately provide for the control of wind
and rainfall erosion from the Blockbuster Expansion. Through the construction
of the proposed erosion control concepts, the City of Fort Collins performance
standards will be met. The proposed erosion control concepts presented in this
report and shown on the erosion control plan are in compliance with the City of
Fort Collins erosion control criteria.
REFERENCES
1.
2.
3.
4.
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Storm Drainage Design Criteria and Construction Standards, by the City of Fort Collins,
Colorado, May 1984.
Erosion Control Reference Manual for Construction Sites, by the City of Fort Collins,
Colorado, January 1991.
Cimarron Plaza P.U.D. Final Drainage Report, by RBD, Inc., September 5, 1985.
Cimarron Plaza P.U.D. - Drive Thru Along Giant Video, by RBD, Inc., February 8,
1990.
GI
� APPENDIX
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HYDROLOGY AND DETENTION
1 '
INC
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Engineering Consultants
2900 South College Avenue
Fort Collins, Colorado 80525
3031226-4955
September 5, 1985
Mr. Tom Gathman
'
City of Fort Collins; ;
P.O. Box 580
Fort Collins, Colorado 80522
'
RE: CIMARRON PLAZA P.U.D.
FINAL DRAINAGE REPORT
'
Dear Tom:
I am pleased to submit this letter report
and supporting cal-
culations as the Final Drainage Report for
the Cimarron Plaza
P.U.D. a development by Arrowstone Development
Corporation.
'
EXISTING SITE CONDITIONS
The 4.55 acre site is located in the NE 1/4
of Section 27, T7N,
R69W of the 6th P.M., more readily described
as a parcel along
'
the southwest corner of Shields Street and
Drake Road in Fort
Collins, Colorado.
' The site is bounded on the North by Drake Road; on the east by
Shields Street; and on the west and south by the Cimarron West
P.U.D.
' EXISTING DRAINAGE
The site currently drains generally to the northeast to a low
' point in the extreme northeast corner of the site. Street flows
along the property drain to a catch basin in Drake Road in the
northeast corner of the site. Recent improvements in connection
' with the Cimarron West development limit offsite flows to those
generated by berming sideslopes adjacent to west and south
property lines.
' DESIGN CRITERIA
The design criteria used on this project is obtained from the
City of Fort Collins Drainage design Criteria; dated March 30,
1
Is
5
' 1984. Both proposed basins are designed to detain 100 year
developed flows onsite and release these flows at the 2 year
historic outfall rate.
' DRAINAGE DESIGN
Cimarron Plaza's drainage design divides the site into two
basins. Parking lot detention is the .principal means of stor-
age. Basin A handles the majority of the site drainage. Basin B
' handles the flows generated in the- extreme southeast corner of
the site and the narrow band of area between the main building
envelope and the.west and south property lines.
' ''Basin A outfalls through two area inlets into a pipe system which
connects to the existing catch basin in the northeast corner of
the site. Out£all is restricted by an oriface plate in the pipe
' which is sized using .the maximum ponding depth. Basin B surface
outflows into the curb along Shields Street.. Detention is
facilitated by highback curb and berming along the south and east
' sides of the southernmost parking.area (SEE GRADING & DRAINAGE
PLAN). Outfall is restricted by an orifice plate installed in
the pipe which penetrates the curbing and landscape berming.
This pipe outfalls into a sidewalks chase which, in turn,
' outfalls in' the Shields Street curb and gutter, The basin
ponding information is summarized below:
P
LJ
BASIN 92 (HISTORIC) DETENTION VOLUME PONDING DEPTH
A 1.08 cfs 35953cf
B 0.76 cfs 6554cf
1.2ft
1.6ft
In a major storm event or if the outlets are blocked Basin A's
detention area will breach along the entrance road off Drake Road
and along the north edge of the parking area. Similarly Basin
B's detention area will breach along the entrance road off
Davidson'Drive and the landscape berm along the parking area.
Conclusions -
When the final design is implemented, this drainage plan will
satisfy hydraulic and hydrologic considerations as well as
current City of Fort Collins Regulations in providing storm water
management.
Very truly yours,
RBD, Inc.
Stan Stan A. Myers, P.E.
���u►tuu�rmur��ii
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9/5/85
ROJ�CT� CIMARRON P\'AZA
CID UN PER 108-002
DESIGN EN[�IN�ER: STAN 11YER3
N� \311-1 ESIGNATION = A
TERMI�E EXISTING Q FOR 2 ,EAR STURM
HISTORIC RUNOFF COEFFICIENT
tSTN SLOPE: .51
4l'.'ISjN LENGTH254
AREA: 3.82 (1CRES
I-I'I.-:-'T TC = 1'87*(1.1-( i
254
-- -'^-
'2
PERCENT
FEET
* '2
�
��I3TORIC
RAINFALL
lNTENSfTY:
1.412473
\�!CHE�/NOi;R
HISTORIC
OUTFALL:
1.07913
CUBIC FEET
PER EECO�D
��ETERMlNATI�N
OF
DETENTION PO�0
VOLU|1E �OR DEyELOPEO [�N'DITl0NS
'
EVEL FED
STORM:
100
=�EVELOPED
RUNOFF
COEFFICIEUT
'85
4.�5875
DURATION
GROSS VOL.
OUTFLOW VOL.
DETFNTION VOL.
N�
.MIN
CU. FT.
CH. FT.
CU. F�
5
10451.52
323.7389
1O127.78
N�
10
l5
1608q.84
20490.il8
647.4778
971.2166
15442'36
19519'26
30
2A329.12
1942.433
26386.�9
45
60
340+6.2
35892.72
2913.65
3884.B67
31122'55
32007'S5
3O78O'64
5827.3
32953'34
120
��9605.76
7769^7",3
31836.O3
180
' 42906'24
11654'6
312�1'�4
N�
360
47856'96
23309'2
24547'7^
EQL�IPED
N�7565046
D�TENT]ON
YOLUME IS
ACRE FEET
�2953.34
CU. FT- OP
3'�2
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'
February 8, 1990
'
Mr. Glen Schlueter
Storm Drainage Department
City of Fort Collins
'
P.O. Box 580
Fort Collins, Colorado 80522
RE: CIMMARRON PLAZA P.U.D. - DRIVE THRU ALONG GIANT VIDEO
Dear Glen,
As per your request, further investigation into the stormwater
analysis of the addition of the Giant Video drive thru has been
' completed.
In our preliminary calculations between the latest drainage and
grading drawing and the original drawing (used for the Drainage
report), an approximate three present (3%) increase in impervious
area was calculated. Further analysis of the hydrologic effects
of the increase in impervious. area was compared to. -results in the
' drainage report. Assuming.that.the basin characteristics were
the same, except for the runoff coefficient "C" - 0.85 for the
original -analysis and 0.875 forthe latest analysis (a 3%
increase) and using the computer method, approved by the City to
' compute the runoff and storage volume required, the results
presented no changes, as shown in the table below and in the at-
tached calculation sheets.
'
Subbasin A
Percent
Peak Historic
Required
Area
Impervious
Runoff
Detention
'
Original Report 3.82 ac
0.85
1.08 cfs
32,953 cf
Current Calcs. 3.82 ac
0.875
1.08 cfs
32,953 of
'
assuming same
basin charact.
- City criteria is to
use 0.85
for this type
of land
development, however, we increased
this value to see the
affect.
In concluding, the addition of the drive thru and revisions up to
now have not increased the runoff or storage volume from the
original drainage report analyses. If you have any questions or
concerns, don't hesitate to contact me or Tom Ochwat.
Very truly yours,
RBb, Inc.
Ted Borstad P.E.
Project Manager
Tom Ochwat
Project Engineer
enc.
cc: Fred Croci, Arrowstone w/enc
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1 DATE: 2-6-90
PROJECT: CIMMARRON PLAZA
JOB NUMBER: 108-006
DESIGN ENGINEER: TMO
BASIN DESIGNATION = BASIN A
' • DETERMINE EXISTING Q FOR 2 YEAR STORM
HISTORIC RUNOFF COEFFICIENT
BASIN SLOPE:
.51
BASIN LENGTH
254
AREA: 3.82
ACRES
HIST TC = 1.,87*(1.1=(
1
.
'.)) * SQRROOT
254
^ 1/3
=
.2
PERCENT
FEET
* .2
))/ .51
33.5645 MINUTES
HISTORIC RAINFALL INTENSITY: 1.412474 INCHES/HOUR
HISTORIC OUTFALL: 1.07913 CUBIC FEET PER SECOND
DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS
DEVELOPED STORM:
100
YEAR STORM
'
DEVELOPED RUNOFF COEFFICIENT
.875
CCFAC = .875
*
1.25
'
..
3..82 =
4.178125
DURATION
GROSS VOL.
OUTFLOW VOL.
DETENTION VOL.
MIN
CU. FT.
CU. FT.
CU. FT
'
5
10451.52
323.7389
10127.78
10
16089.84
647.4778
15442.36
15
20490.48
971.2168
19519.26
'
30
28329.12
1942.434
26386.69
45
34036.2
2913.65
31122.55
60
35892.72
3884.867
32007.85
'
90
120
38780.64
39605.76
5827.301
7769.734
32953.34
31836.02
180
42906.24
11654.6
31251.64
360
47856.96
23309.2
24547.76
'
REQUIRED
DETENTION
VOLUME IS
32953.34
CU. FT. OR
.7565046
ACRE FEET
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'Blockbuster
Expansion at Cimarron Plaza
108-008
Detention -- Mass Balance Calculation
'
Site Conditions/Limitations
Notes -- --
Historic storm (2-yr):
Q =
1.08 cfs
(1)
Developed storm (100-year):
A =
3.82 ac
(1)
C =
0.87
(2)
'
Cf =
1.25
CxCf =
1.00
Ax(CXCo
166,399 ft3
'
Duration Intensity
Inflow
Outflow Detention
(in/hr)
(ft3)
(ft3)
(ft3)
(1)
------------
----------- —
-------------------------
5 9.04
10,452
324
10,128
10 6.96
16,090
647
15,442
15 5.91
20,490
971
19,519
30 4.09
28,329
1,942
26,387
45 3.27
34,036
2,914
31,123
'
60 2.59
90 1.86
35,893
38,781
3,885
5,827
32,008
32,953
120 1.43
39,606
7,770
31,836
180 1.03
42,906
11,655
31,252
'
360 0.58
47,857
23,309
24,548
Required detention
32,953 ft3
'
Notes:
1. From 1985 final drainage report.
2. Runoff coefficient with
building expansion.
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WON
' OPEN CHANNEL FLOW ANALYSIS:TRAPEZOIDAL CHANNEL
Developed by James Guo, Civil Eng. Dept, U of Colorado at Denver
Metro Denver Cities/Counties and UD&FCD Pool Fund Study
--------------------------------------------------------------
User= :KEVIN GINGERY RBD INC. FT. COLLINS
COLORADO .............................
ON DATE 10-24-1995 AT TIME 13:59:21
'*** PROJECT TITLE: Blockbuster @ Cimarron
CHANNEL ROUGHNESS IS GIVEN
'*** DESIGN FLOW RATE AND CHANNEL GEOMETRIES:`��.✓aL.E-
FLOW RATE (CFS) =
2.20 _ n9 (*2
'
MANNING ROUGHNESS =
0.0600
CHANNEL SLOPE (FT/FT)=
0.0040
BOTTOM WIDTH (FEET)=
2.00
RIGHT SIDE SLOPE(FT/FT)=
4.00
LEFT SIDE SLOPE(FT/FT)=
12.00
'*** NORMAL FLOW CONDITIONS:
FLOW DEPTH
(FEET)=
0.51
FLOW AREA
(SQ FT)=
3.11
FLOW VELOCITY
(FPS)=
0.71
WETTED PERIMETER
(FEET)=
10.26
TOP WIDTH
(FEET)=
10.17
FROUDE NUMBER
=
0.23
'
SPECIFIC FORCE
(KLB)=
0.04
SPECIFIC ENERGY
(FEET)=
0.52
SEQUENT DEPTH
(FT)=
0.09
'
ALTERNATE'DEPTH
(FT)=
0.14
***
CRITICAL FLOW CONDITIONS:
'
DEPTH
(FEET)=
0.24
FLOW AREA
(SQ FT)=
0.96
'
FLOW VELOCITY
WETTED PERIMETER
(FPS)=
(FEET)=
2.29
5.94
MINIMUM SPECIFIC
FORCE
(KLB)=
0.02
MINIMUM SPECIFIC
ENERGY
(FT)=
0.3248
'
SLOPE
(FT/FT)=
0.0959
RECOMMENDATIONS ON FREEBOARD:
' FOR CONCRETE CHANNEL (2.0+0.025*VELOCITY*DEPTH"0.33)= 2.01 FEET
FOR A MAJOR DRAINAGE CHANNEL (100-YR FLOOD) >= 1.0 FOOT
FOR A MINOR DRAINAGE CHANNEL (2 OR 5-YR FLOOD) >= 0.51 FEET
' RECOMMENDATIONS FOR ERODABLE CHANNEL:
(MINOR FLOOD) 2 <= FLOW VELOCITY <= 5 TO 7 FPS (MAJOR FLOOD)
FROUDE NUMBER (TURBULENCE FACTOR)<= 0.80
E CHANNEL:
(MINOR FLOOD) 2 <= FLOW VELOCITY <=
------------------
-OPEN CHANNEL FLOW ANALYSIS:TRAPEZOIDAL CHANNEL
Developed by James Guo,
Civil Eng. Dept, U of Colorado at Denver
Metro Denver Cities/Counties
and UD&FCD Pool Fund Study
User= :KEVIN GINGERY RBD INC. FT. COLLINS
COLORADO .............................
ON DATE 10-24-1995 AT
TIME 14:00:16
'
*** PROJECT TITLE: Blockbuster
@ Cimarron
CHANNEL ROUGHNESS IS GIVEN
'
*** DESIGN FLOW RATE AND CHANNEL
GEOID'IETRIES_:___��faT__.���4G--�!LTt,4N__`�v�L�
FLOW RATE (CFS) =
2.9 3_J_ _5 �fd _b1=�J001K - �d`� - -----
MANNING ROUGHNESS =
0.0600
CHANNEL SLOPE (FT/FT)=
0.0040
BOTTOM WIDTH (FEET)=
2.00
RIGHT SIDE SLOPE(FT/FT)=
4.00
'
LEFT SIDE SLOPE(FT/FT)=
12.00
'
*** NORMAL FLOW CONDITIONS:
FLOW DEPTH (FEET)=
0.58
FLOW AREA (SQ FT)=
3.64
'
FLOW VELOCITY (FPS)=
0.76
WETTED PERIMETER (FEET)=
11.37
TOP WIDTH (FEET)=
11.27
FROUDE NUMBER =
0.23
'
SPECIFIC FORCE (KLB)=
0.06
SPECIFIC ENERGY (FEET)=
0.59
SEQUENT DEPTH (FT)=
0.10
'
ALTERNATE -DEPTH (FT)=
0.17
*** CRITICAL FLOW CONDITIONS:
'
DEPTH
(FEET)= 0.28
FLOW AREA
(SQ FT)= 1.20
FLOW VELOCITY
WETTED PERIMETER
(FPS)- 2.43
(FEET)= 6.57
MINIMUM SPECIFIC FORCE
(KLB)= 0.02
MINIMUM SPECIFIC ENERGY
(FT)= 0.3745
SLOPE
(FT/FT)= 0.0920
RECOMMENDATIONS ON FREEBOARD:
FOR CONCRETE CHANNEL (2.0+0.025*VELOCITY*DEPTH-0.33)= 2.02 FEE
'
FOR A MAJOR DRAINAGE CHANNEL (100-YR FLOOD) >= 1.0 FOOT
FOR A MINOR DRAINAGE CHANNEL (2 OR 5-YR FLOOD) >= 0.51 FEET
' RECOMMENDATIONS FOR ERODABLE CHANNEL:
(MINOR FLOOD) 2 <= FLOW VELOCITY <= 5 TO 7 FPS (MAJOR FLOOD)
FROUDE NUMBER (TURBULENCE FACTOR)<= 0.80
' E CHANNEL:
(MINOR FLOOD) 2 <= FLOW VELOCITY <=
i -::5 t-
' OPEN CHANNEL FLOW ANALYSIS:TRAPEZOIDAL CHANNEL
Developed by James Guo, Civil Eng. Dept, U of Colorado at Denver
Metro Denver Cities/Counties and UD&FCD Pool Fund Study
User=W:KEVIN GINGERY RBD INC. -FT. ~COLLINS
COLORADO .............................
ON DATE 10-24-1995 AT TIME 09:49:35
** PROJECT TITLE: Blockbuster @ Cimarron
CHANNEL ROUGHNESS IS GIVEN
t** DESIGN FLOW RATE AND CHANNEL GEOMETRIES:
FLOW RATE (CFS) = 2.93
' MANNING ROUGHNESS = 0.0130
CHANNEL SLOPE (FT/FT)= 0.0040
BOTTOM WIDTH (FEET)= 2.00
' RIGHT SIDE SLOPE(FT/FT)= 0.00
LEFT SIDE SLOPE(FT/FT)= 0.00
'*** NORMAL FLOW CONDITIONS:
FLOW DEPTH
(FEET)=
0.44
FLOW AREA
(SQ FT)=
0.89
FLOW VELOCITY
(FPS)=
3.30
WETTED PERIMETER
(FEET)=
2.89
TOP WIDTH
(FEET)=
2.00
FROUDE NUMBER
=
0.87
'
SPECIFIC FORCE
(KLB)=
0.03
SPECIFIC ENERGY
(FEET)=
0.61
SEQUENT DEPTH
(FT)=
0.37
'
ALTERNATE -DEPTH
(FT)=
0.38
***
CRITICAL FLOW CONDITIONS:
'
DEPTH
(FEET)=
0.41
FLOW AREA
(SQ FT)=
0.81
FLOW VELOCITY
WETTED PERIMETER
(FPS)=
(FEET)=
3.61
2.81
MINIMUM SPECIFIC
FORCE
(KLB)
0.03
MINIMUM SPECIFIC
ENERGY
(FT)=
0.6082
'
SLOPE
(FT/FT)=
0.0052
RECOMMENDATIONS ON FREEBOARD:
' FOR CONCRETE CHANNEL (2.0+0.025*VELOCITY*DEPTH-0.33)= 2.06 FEET
FOR A MAJOR DRAINAGE CHANNEL (100-YR FLOOD) >= 1.0 FOOT
FOR A MINOR DRAINAGE CHANNEL (2 OR 5-YR FLOOD) >= 0.67 FEET
RECOMMENDATIONS FOR ERODABLE CHANNEL:
(MINOR FLOOD) 2 <= FLOW VELOCITY <= 5 TO 7 FPS (MAJOR FLOOD)
FROUDE NUMBER (TURBULENCE FACTOR)<= 0.80
E CHANNEL:
(MINOR FLOOD) 2 <= FLOW VELOCITY <=
1
I
I
I
1�
' RBD, Inc.
RAINFALL PERFORMANCE STANDARD EVALUATION
' #108-008
1
1
PROJECT: Blockbuster Expansion STANDARD FORM,
CALCULATED BY: DKT DATE: 07/20/95
DEVELOPE
ERODIBILIT
Asb
Lsb
Ssb
Lb
Sb
PS
SUBBASIN
ZONE
(ac)
(ft)
(%)
(ft)
(%)
(%)
A
moderate
0.10
100
2.0
Total
0.10
100
2.0
78.4
EXAMPLE CALCULATIONS
' Lb = sum(AiLi)/sum(Ai) = (0.10 x 100 + ... + 0.00 x 0)/ 0.10
100 ft
Sb = sum(AiSi)/sum(Ai) = (0.10 x 2.00 + ... + 0.00 x 0.00)/ 0.10
2.0 %
'PS (during construction) = 78.4 (from Table 8A)
PS (after construction) = 78.4/0.85 = 92.2
1
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E-4
DESIGN CRITERIA
16
J�
RBD, Inc.
IEFFECTIVENESS CALCULATIONS
' #108-008
0
r
PROJECT: Blockbuster Expansion STANDARD FORM B
CALCULATED BY: DKT DATE: 07/20/95
Erosion Control
C-Facto
P-Facto
Comment
Number Method
Value
Value
9 Asphalt/Concrete Pavement
0.01
1
paved and constructed
20 Sod Grass
0.01
1
SUB
PS
AREA
BASIN
N
(ac)
S ite
92.2
0.10
SUB
SUB
AREA
Practice C *A P * A Remarks
BASIN
AREA
(ac)
AFTER CONSTRUCTION
A
Total
0.10
Impervious
0.02
9 0.00 0.02 Asphalt/Concrete Pavement
Remain.
0.08
20 0.00 0.08 Sod Grass
Cnet = [0.02x0.01+...+0.08x0.01]/0.02
= 0.01
Pnet = [0.02x1.00+...+0.08x1.00]/0.02
1.00
EFF = (1-C*P)100 = (1-0.01*1.00)100
= 99,00
> 92.2 (PS)
�0
.1
'I
.1
Table 813 C-Factors and P-Factors for Evaluating EFF Values.
Treatment C-Factor
P-Factor
BARE SOIL
Packedand smooth................................................................
1.00
1.00
Freshlydisked.......................................................................
1.00
1.00
0.90
0.90
Roughirregular surface...........................................................
SEDIMENT BASIN/TRAP.................................................................
1.00
0.5011)
STRAW BALE BARRIER, GRAVEL FILTER, SAND BAG ........................
1.00
0.80
SILTFENCE BARRIER.............................................................. I......
1.00
0.50
ASPHALT/CONCRETE PAVEMENT ...................................................
0.01
1.00
ESTABLISHED DRY LAND (NATIVE) GRASS .......................... See Fig.
8-A
1.00
SODGRASS.................................................................................
0.01
1.00
TEMPORARY VEGETATION/COVER CROPS .................................... 0.451=l
1.00
HYDRAULIC MULCH @ 2 TONS/ACRE........................................... 0.10"'
1.00
SOIL SEALANT....................................................................0.01-0.60"'
1.00
EROSION CONTROL MATS/BLANKETS............................................
0.10
1.00
GRAVEL MULCH
Mulch shall consist of gravel having a diameter of approximately
1/4" to 1 1/2" and applied at a rate of at least 135 tonslacre..............
0.05
1.00
HAY OR STRAW DRY MULCH
After glanting grass seed, apply mulch at a rate of 2 tonslacre (minimum)and adequately
anchor,
tack or crimp material into the soil.
Slope (%)
- 1 to 05.............................................................................0.06
1.00
6 to - 10.............................................................................
0.05
1.00
11 -to 15.............................................................................
0.07
1.00
16 to 20............................................................................
0.11
1.00
21 to 25.............................................................................
0.14
1.00
25 to 33.............................................................................0.17
1.00
> 33..........................................................................
0.20
1.00
NOTE: Use of otiw C-Factor or P-Factor values reported in this table must be substar�ated by documentation.
(1) Must be constructed as the first step in overlot grading.
(2) Assumes planting by dates identified in Table 11-4, thus dry or hydraulic mulches are not required.
(3) 'Hydraulic! mulches shall be used only between March 15 and May 15 unless irrigated:
(4) Value used must be substantiated by documentation.
MARCH 1SS1
8-6
DESIGN CRITERIA
EROSION CONTROL CONSTRUCTION SEQUENCE
PROJECT: Blockbuster Expansion STANDARD FORM C
CALCULATED BY: DKT DATE: 11/06/95
SEQUENCE FOR 4995 ONLY
Indicate by use of a bar line or symbols when erosion control measures will be installed.
Major modifications to an approved schedule may require submitting a new schedule for
approval by the City Engineer.
YEAR 95 96
MONTH J A S O N D J F M A M J
OVERLOT GRADING
WIND EROSION CONTROL
Soil Roughening
Perimeter Barrier
Additional Barriers
Vegetative Methods
Soil Sealant
Other
RAINFALL EROSION CONTROL
STRUCTURAL:
Sediment Trap/Basin
Inlet Filters
Straw Barriers
Silt Fence Barriers
Sand Bags
Bare Soil Preparation
Contour Furrows
Terracing
Asphalt/Concrete Paving
Other
VEGETATIVE:
Permanent Seed Planting
Mulching/Sealant
Temporary Seed Planting
Sod Installation
Nettings/Mats/Blankets
Other
STRUCTURES: INSTALLED BY
' VEGETATION/MULCHING CONTRACTOR
DATE SUBMITTED
1
MAINTAINED BY
APPROVED BY CITY OF FORT COLLINS ON
)9
I
RBD, Inc.
1
[I
EROSION CONTROL COST ESTIMATE
Blockbuster Expansion
PREPARED BY:
DKT
DATE: 11/06/95
PM RESEEDINC; COST
Unit
Total
Method
Quantity Unit
Cost
Cost Notes
Reseed/mulch
0.1 ac
$1,300
$130 See Note 1.
Subtotal
$130
Contingency
50%
$65
Total
$195
EROSION CONTROL MEASURES
Unit
Total
Number Method
Quantity Unit
Cost
Cost Notes
8 Silt Fence Barrier
274 LF
$3
$822
Subtotal
$822
Contingency
50%
$411
Total
$1,233
Total Security
$1,233
Notes: 1. A<1 ac=$1300/ac; A=1-10 ac=$650/ac; A>10 ac=$500/ac.