HomeMy WebLinkAboutWILL SUBDIVISION, 742 - 746 N. COLLEGE - PDP/FDP - 20-98 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTAPPENDIX III
Stuffer Envelope
Drainage and Erosion Control Plan
Floodplain Exhibit
Table 3-3
RATIONAL METHOD RUNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS
Character of Surface Runoff Coefficient
Streets Parking Lots, Drives:
Asphalt 0.95
Concrete 0.95
Gravel 0.50
Roofs 0.95
Lawns, Sandy Soil:
Flat < 2%
0.10
Average 2 to 7%
0.15
Steep > 7%
0.20
Lawn, Heavy Soil:
Flat < 2%
0.20
Average 2 to 7%
0.25
Steep > 7%
0.35
Table 3-4
RATIONAL METHOD FREQUENCY ADJUSTMENT FACTORS
Storm Return Period Frequency Factor
years Cf
2-10
1.0
11-25
1.1
26-50
1.20
51-100
1.25
Note: The product of C times Cf shall not exceed 1.0
tables
No Text
APPENDIX H
Charts & Figures
SHEAR ENGINEERING CORPORATION
DEVELOPED
PAGE
PLOW TO CONCENTRATION POINT A
FROM BASIN 1
PROJECT:
PERBNIAL GARDENER
DATE
04/01/98
LOCATION:FORT
COLLINS
PROJ. NO.1608-01-98
PILE:
RATZIB
BY
MEO
AREA (A)- 1.780 ACRES
RUNOFF CORP. (C)
2 YEAR
10 YEAR
100 YEAR
C = 0.42
0.42
0.53
SEE SPREAD SHEET ATTACHED ON PAGE 2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
not applicable
LENGTH =na FEET
SLOPE -na
tr
2 YEAR
10 YEAR
100 YEAR
C = 0.20
0.20
0.25
Ti (min)- 0.00
0.00
0.00
TRAVEL TIME (Tt) =L/(60*V)
FLOW TYPE
L-(ft) - 250 S (1) -
0.50 gutter
V (fps) =
1.50
Tt(min)=
2.78
L (ft) = 50 S (t) -
0.50 lawn
V (fps) -
0.50
Tt(min)=
1.67
L (ft) _? S (t) =
0.00 none
V (fps) =
0.00
Tt(min)=
0.00
L (ft) _? S (t) -
0.00 none
V (fps) =
0.00
Tt(min)=
0.00
L (ft) _? S M -
0.00 none
V (fps) =
0.00
Tt(min)-
0.00
L (ft) _? S (14)
= 0.00 none
V (fps) =
0.00
Tt(min)=
0.00
L (ft) _? S (9)
- 0.00 none
V (fps) =
0.00
Tt(min)=
0.00
ALL VELOCITIES TAKEN FROM FIGURE 3-2
TOTAL TRAVEL
TIME
(min) =
4.44
TOTAL LENGTH = 300
L/180+10= 11.67
>
4.44
-Ti+Tt CHOOSE LESSER
To =Ti+TOTAL TRAVEL TIME
2 YEAR
10 YEAR
100 YEAR
Tc (min)- 4.44
4.44
4.44
USE To = 5
5
5
INTENSITY (I) (iph)
2 YEAR
10 YEAR
100 YEAR
I = 3.29
5.64
9.30
NOTE: INTENSITIES TAKEN
FROM FIGURE
3-1
RUNOFF (Q= CIA) (cfe)
2 YEAR
10 YEAR
100, YEAR
Q = 2.47
4.23
8.72
VERSUS
QHIST = 2.47
4.23
8.72
CONCLUDE:NO CHANGE TO SITE THEREFORE NO INCREASE IN PLOW DUE TO PROJECT
4
SHEAR ENGINEERING
CORPORATION
HISTORIC
PLOW TO CONCENTRATION POINT A
FROM BASIN
1
PROTECT: PERENIAL GARDENER
DATE
04/01/98
LOCATION:PORT COLLINS
PROJ.
NO.1608-01-98
FILE: RATZIB
BY
MEO
AREA (A)= 1.780 ACRES
PAGE 3
RUNOFF CORP. (C)
2 YEAR
10 YEAR
100 YEAR
C = 0.42
0.42
0.53
899 SPREAD SHEET ATTACHED ON PAGE 2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
not applicable
LENGTH =na FEET
SLOPE -na
•
2 YEAR
10 YEAR
100 YEAR
C = 0.20
0.20
0.25
Ti (min). 0.00
0.00
0.00
TRAVEL TIME (Tt) =L/(60•V)
PLOW TYPE
L (ft) = 250 S (4) -
0.50 gutter
V (fps) =
1.50
Tt(min)=
2.78
L (ft) - 50 S M -
0.50 lawn
V (fps) -
0.50
Tt(min)-
1.67
L (ft) _? S (_) -
0.00 none
V (fps) -
0.00
Tt(min)=
-0.00
L (ft) _? S (4) =
0.00 none
V (fps) -
0.00
Tt(min)=
0.00
L (ft) =7 S (4) =
0.00 none
V (fps) =
0.00
Tt(min)=
0.00
L (ft) =7 S (}) -
0.00 none
V (fps) =
0.00
Tt(min)=
0.00
L (ft) _? S (%) -
0.00 none
V (fps) -
0.00
Tt(min)=
0.00
ALL VELOCITIES TAKEN FROM FIGURE 3-2
TOTAL TRAVEL
TIME
(min)
4.44
TOTAL LENGTH = 300
L/180+10= 11.67
>
4.44
-Ti+Tt CHOOSE LESSER
Tc -Ti+TOTAL TRAVEL TIME
2 YEAR
10 YEAR
100 YEAR
Tc (min)= 4.44
4.44
4.44
USE Tc = S
5
5
INTENSITY (I) (iph)
2 YEAR
10 YEAR
100 YEAR
I = 3.29
5.64
9.30
NOTE: INTENSITIES TAKEN
FROM FIGURE
3-1
RUNOFF (Q= CIA) (cfe)
2 YEAR
10 YEAR
100 YEAR
Q = 2.47
4.23
8.72
CONCLUDE: COMPARE WITH DEVELOPED FLOWS
SHEAR ENGINEERING CORPORATION
SUBBASIN BREAKDOWN
PAGE
2
PROJECT:
PERENIAL GARDENER
DATE
04/01/98
LOCATION:FORT
COLLINS
BY
MHO
PROD. NO.1608-01-98
PILE:
RATZIB
TOTAL SITE AREA = 1.78
TOTAL BASIN AREA = 1.78
SUB BASINS
HISTORIC DEVELOPED
ASPHALT
0.02 0.02
CONCRETE
0.09 0.09
GRAVEL
0.64 0.64
ROOFS
0.16 0.16
LAWNS,SANDY SOIL
PLAT < 21,
0.00 0.00
AVERAGE 2 TO 7i
0.00 0.00
STEEP > 7%
0.00 0.00
LAWNS, HEAVY SOIL:
PLAT < 21,
O.B7 0.87
AVERAGE 2 TO 71,
0.00 0.00
STEEP > 7%
0.00 0.00
TOTAL
1.78 1.78
RUNOFF COEFFICIENT SUB BASINS AND /
OR BASINS
HISTORIC DEVELOPED
C2-C10
0.42 0.42
C100 = 1.25*C2
0.53 0.53
C100 IS NEVER GREATER THAN 1.0
NOTE: THERE WILL BE NO CHANGE TO THE SITS WITH THIS PROJECT.
WORK WILL BE LIMITED TO REMODELLING THE BUILDING.
PLOW SUMMARY FOR 742-746 NORTH COLLEGE AVENUE PAGE 1
DATE: 04/01/98
DESIGN CONTRIBUTING AREA C2 C10 C100 Tc Tc I2 I100 Q2 0100 PAGE
POINT SUB 2,10 100
BASIN(S) ac. min. min iph iph cfe cEe
rr•rrererrrvrrr»rrre rrrrrv♦rerrrr r: rrrrrrrrrr•rrrrrrrrrrrrrrrrrerrrrr:r•rrerrrr rr rrrrrr:rr
HISTORIC
A 1 1.78 0.42 0.42 0.53 5.00 5.00 3.29 9.30 2.47 8.72 3
DEVELOPED
A 1 1.78 0.42 0.42 0.53 5.00 5.00 3.29 9.30 2.47 8.72 4
APPENDIX I
Drainage Calculations
Page 5
Final Drainage and Erosion Control Report
Project No: 1608-01-98
V. EROSION CONTROL:
A. General Concept
1. No erosion control devices are anticipated. Generally, no specific site work is planned.
Possible parking lot pavement repairs may be considered. The limit of the site work
will be limited to the removal and replacement of damaged concrete / asphalt.
B. Specific Details
1. No Erosion Control devices will be required.
VI. CONCLUSIONS:
A. Compliance with Standards
1. All drainage analysis has been performed according to the requirements of the City of
Fort Collins Storm Drainage Criteria Manual.
B. , Drainage Concept
1. The proposed drainage design for this site has'not changed.
2. There will be no effect on City of Fort Collins Master Drainage Plan recommendations.
VIL REFERENCES:
1. City of Fort Collins "Storm Drainage Design Criteria and Construction Standards";
May, 1984
2. City of Fort Collins "Erosion Control Reference Manual"; January, 1991
3. City of Fort Collins "STORMWATER BASIN MAP
4. Improvement Survey for 742-746 North College Avenue; Hall and Associates, Inc.;
Survey dated 02/01/95.
Page 4
Final Drainage and Erosion Control Report
Project No: 1608-01-98
IV. DRAINAGE FACILITY DESIGN:
A. General Concept
1. Runoff is conveyed to the Lake Canal primarily by overland flow. Runoff is conveyed
to the existing drainage channel east of this site, primarily by overland flow with minor
conveyance via underground storm sewer flow.
2. No drainage facility improvements are planned with this project.
B. Specific Details
1. No drainage facility improvements are planned with this project.
2. Existing surface coverage is based on an Improvement Survey provided by Hall and
Associates, Inc. of Loveland. The following table summarizes the existing developed
surface cover for the project site. This table is summarized for both Lots 1 and 2.
SURFACE COVER:
Existing:
Proposed:
Asphalt
0.21 acres
unchanged
Concrete
0.10 acres
unchanged
Gravel
0.52 acres
unchanged
Building roof
0.16 acres
unchanged
Undeveloped (lawns; less than 2%)
0.79 acres
unchanged
TOTALS:
1.78 acres
The average runoff coefficient for the existing site has been determined to be 0.49 for 2 to
10 year storms and 0.61 for the 100-year storm.
Page 3
Final Drainage and Erosion Control Report
Project No: 1608-01-98
III. DRAINAGE DESIGN CRITERIA:
A. Regulations
1. This final report was prepared in accordance with the requirements of the current City
of Fort Collins Storm Drainage Design Criteria and Erosion Control Criteria.
2. All items requested by the Stormwater Utility noted in the Conceptual Review letter,
have been addressed.
B. Development Criteria Reference and Constraints
1. Because the site is currently developed, constraints occur around the perimeter of the
site.
a. Utilities and underground drainage facilities encumber the site (See Plan).
M. DRAINAGE DESIGN CRITERIA:
C. Hydrological Criteria
1. The Rainfall -Intensity -Duration curves for the City of Fort Collins were used (Figure 3-
1, attached for reference), in conjunction with the "Rational Method" for determining
peak flows. Peak flows were calculated for documentation purposes only.
2. Runoff calculations at various design points are based on the "Rational" method. The
2, 10, and 100-year storms have been analyzed.
3. Runoff coefficients utilized were as suggested by the City of Fort Collins Storm
Drainage Criteria Manual.
D. Hydraulic Criteria
1. Drainage channel capacities were based on the Mannings Equation. The Mannings
coefficients are as suggested by the City of Fort Collins Storm Drainage Criteria
Manual.
Page 2
Final Drainage and Erosion Control Report
Project No: 1608-01-98
H. DRAINAGE BASINS AND SUB -BASINS:
A. Major Basin Description
4. All of the site is in the 100-year flood plain as delineated on,the Flood Insurance Rate
Map (FIRM) for the City of Fort Collins, Community Panel Number 080102-0004-C;
dated March 18, 1996. Refer to the floodplain exhibit in Appendix III of this report.
B. Sub -Basin Description
1. Runoff from a majority of the existing developed site, flows directly to the Lake Canal.
The remainder of the site currently flows to the east to an existing drainageway, east of
the site.
2. The site is extremely flat. The slope of the land is generally less than 1.0%.
3. An existing box culvert traverses the property from west to east. The box culvert
appears to be for drainage purposes only. It conveys stormwater from the west side of
North College Avenue to the east side of North College Avenue. The box culvert
discharges into the Josh Ames ditch east of the property.
a. The box culvert entry. is located on the west side of North College Avenue,.directly
across from this site.
b. The box culvert has been identified as an extension to the Josh Ames Ditch.
4. The drive located immediately north of the existing building, has an inverted crown and
is utilized as a drainageway for a portion of this site and for a portion of the Milan
Minor Subdivision to the north. Stormwater conveyance immediately east of this site
and the Milan Minor Subdivision site, is not well defined and does not appear to reach
the drainageway located east of the site.
a. The Milan Minor Subdivision is fully developed and is currently utilized as an auto
sales facility.
b. The drive / drainageway is. on the Milan Minor Subdivision property. A 24' access
easement exists and was recorded in Book 103, at Page 19 in Larimer County
Records.
5. No detention has been provided with this site. No detention will be provided now since
the site is "Grandfathered" and there will not be an increase in impervios area over 350
square feet.
Page 1
Final Drainage and Erosion Control Report
Project No: 1608-01-98
L GENERAL LOCATION AND DESCRIPTION:
A. Location
1. 742-746 North College Avenue is located in the Southwest 1/4 of Section 1, T7N,
R69W of the 6th P.M., Fort Collins, Colorado.
2. More specifically, the site is located at 742 North College Avenue.
3. The site is bounded on the south by the Lake Canal, on the west by North College
Avenue, on the north by Milan Minor Subdivision and on the east by undeveloped and
unplatted property.
B. Description of Property
1. The Project will consist of the remodel of an existing building which was formally
"Dimmers Brew Pub" and prior to that, "Gabbys Restaurant".
2. The site will be platted into two (2) lots. The existing building will be located on Lot 1,
Will Subdivision as shown on the Final Plat. Lot 2, Will Subdivision will be retained
for future development.
3. Total site area under consideration is 77,588 square feet or 1.78 acres, more or less.
a. Lot 1 is 35,468 square feet (0.81 acres).
b. Lot 2 is 42,102 square feet (0.97 acres).
4. There are existing utilities which service the site. They are located in North College
Avenue and within the site.
It. DRAINAGE BASINS AND SUB -BASINS:
A. Major Basin Description
1. The site is located within the Dry Creek Basin as defined on the City of Fort Collins
Master Stormwater Basin Map.
a. The Basin Rate fee for the Dry Creek Basin is $ 5,000 per acre.
b. No fees are required if the development of the site increases the imperviousness by
less than 350 square feet.
2. The flow pattern of this portion of the Dry Creek Basin is generally easterly and
southerly. Runoff is primarily conveyed in ditches to the Cache La Poudre River.
3. The Lake Canal ditch is located immediately adjacent to this site. A portion of the
ditch is actually on the southern portion of the site.
April 1, 1998
Project No: 1608-01-98
Basil Hamdan
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: 742 - 746 North College Avenue; Fort Collins, Colorado
Dear Basil,
Enclosed, please find the Final Drainage and Erosion Control Report for 742-746 North College
Avenue. This is the old "Gabby's" and "Dimmers Brew Pub" site and is developed. The project is
primarily a remodel project with little or no change on the site. This report has been prepared,
primarily to document the existing surface treatments and flow patterns according to the
conceptual review note requirements of the Stormwater Utility from the December 1, 1997
conceptual review meeting.
The existing building will be situated on Lot 1 of the proposed Will Subdivision. Lot 2 will be
retained for possible future development. This report only considers the historic conditions for Lot
2. A separate Drainage and Erosion Control Report and Plan will be required when a proposal for
development for Lot 2 is made.
If you have any questions or comments, please call me or Mark Oberschmidt at (970) 226-5334.
Brian W. Shear, P.E. '
Shear Engineering Corporation
BWS / meo
cc: Ted Zibell
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282.031 1
M
SHEAR
ENGINEERING
CORPORATION
Final Drainage and Erosion Control Report
for
742 - 746 North College Avenue
(Will Subdivision)
Fort Collins, Colorado
Prepared for:
Perennial Gardener
Attn: Ted Zibell
154 North College Avenue
Ft. Collins, Colorado 80524
Prepared by:
1
t
'1 Shear Engineering Corporation
Project No: 1608-01-98
Date: April, 1998 1Nl1nALSUBMI7TA1,\
date*af_
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-0311
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