HomeMy WebLinkAboutMULBERRY / LEMAY CROSSINGS PUD, LOT 2, FILING 2 - FINAL PUD - 36-96E - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTFINAL DRAINAGE ANALYSIS
- LOT 2-
MULBERRY AND LEMAY CROSSINGS
FT COLLINS, COLORADO
Vill. REFERENCES
1. Storm Drainage Design Criteria Manual (SDDCM), City of Fort Collins, Colorado,
May, 1984.
2. Urban Storm Drainage Criteria Manual, Denver Regional Council of
Governments, Denver, Colorado March 1969 (with current revisions).
3. Poudre Master Drainageway Plan, Chapter 7, City of Fort Collins Stormwater
Utility, by Ayres Associates, Fort Collins, Colorado, September, 1995.
4. StormCAD v. 1.5, by Haestad Methods, Inc., 1997.
FINAL DRAINAGE ANALYSIS
- LOT 2-
MULBERRY AND LEMAY CROSSINGS
FT COLLINS, COLORADO
V. STORMWATER QUALITY CONTROL PLAN
Stormwater quality is addressed in the design of the detention pond P2. Details for
the design and construction of the pond appear in the previous report.
VI. CONSTRUCTION ACTIVITIES STORMWATER MANAGEMENT PLAN
Construction Activities Erosion Control
Erosion control during the construction period will be outlined on the Grading and
Drainage and Erosion Control plan. Silt fences will be used along the edges of
the site abutting public right-of-way. The fence will be placed behind the back of
curb or, in the case of an attached sidewalk, behind the back of walk. Inlet
protection, consisting of gravel filters will be used for all of the inlets until disturbed
areas are paved or landscaping is established. The contractor is advised to use
vehicle tracking control where vehicles enter and exit the site.
Permanent Stabilization
When complete, all of the site will be either paved or landscaped. Landscaping
will be either gravel mulch or turf grass. No reseeding will be done.
VII. CONCLUSIONS
1. Calculations for the runoff coefficients for the proposed development
appear to comply with the values calculated in the previous report.
2. Hydraulic calculations for the proposed inlets and storm sewer appear to
be in agreement with drainage concept as set forth in the previous report.
3
FINAL DRAINAGE ANALYSIS
- LOT 2-
MULBERRY AND LEMAY CROSSINGS
FT COLLINS, COLORADO
Developed Drainage
Lot 2, as developed, will be divided into two principal sub -basins with a total area
of approximately 16.51 acres.
Basin B The area along the west side of the site. Runoff from this area is
collected into Storm Sewer System B and conveyed to Pond P2.
Basin C The area along the east side of the site south of the proposed
Magnolia Street. Sub -basins are collected in Storm Sewer system
C and piped to detention Pond 2.
III. DRAINAGE DESIGN CRITERIA
This analysis was prepared in accordance with the Storm Drainage Design
Criteria Manual (SDDCM) of the City of Fort Collins and the Urban Drainage and
Flood Control Manual (UDFCM).
Runoff values for the 10-year rainfall event were used to size storm sewer.
Calculations were done with StormCAD by Haestad Methods which uses the
Rational Method as allowed under Section 5.2 of the City of Fort Collins Storm
Drainage Design Criteria. The analysis was done with the latest
time/intensity/frequency curves provided by the City. A five minute time of
concentration was used for each sub -basin.
IV. DRAINAGE FACILITY DESIGN
Storm sewers across the site will be used to drain low points in parking areas.
Major storms will partially be collected in the sewers but are allowed to proceed
overland to the detention ponds. Proposed finished floor elevations will be set to
18 inches above the floodplain, which varies from west to east across the site, as
indicated on the FIRM panels shown in the appendix.
A detention pond, sub -basin P2, is located in the southwest comer of the site.
Details for the design and construction of the pond were included in the previous
study.
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FINAL DRAINAGE ANALYSIS
- LOT 2-
MULBERRY AND LEMAY CROSSINGS
FT COLLINS, COLORADO
I. GENERAL LOCATION AND DESCRIPTION
Lot 2 of Mulberry and Lemay Crossings is approximately 16.51acres. It is
bordered on the north by Magnolia Street, the south by Mulberry street (Colorado
Highway 14), the west by Lemay Avenue, and the east by 12th Street. The site is
a portion of the development previously analyzed in the Final Drainage Analysis,
Mulberry and Lemay Crossings, Ft. Collins, Colorado, prepared by CLC
Assoicates, September, 1999. This report is an amendment thereto.
Construction drawings for the site show an overlot grading condition with
constructed storm sewer traversing the site. The southwest comer of the site is
a detention pond that serves the entire site and release storm water south to the
Poudre River.
The purpose of this report will be to:
1. Provide a detailed analysis and comparison of runoff coefficients to
demonstrate compliance with the previous report, and
2. Provide final storm inlet sizing and supplemental storm sewer hydraulics
for proposed storm sewer not analyzed in the previous report.
II. DRAINAGE BASINS AND SUB -BASINS
Historic Drainage
The site lies within the Poudre River drainage basin. Historically, the stormwater
from the site is directed south where it collects in low points on the north side of
Mulberry Street. Culverts at various locations along the right-of-way allow the
stormwater to pass under Mulberry and the developed area to the south where it
enters the Poudre River.
The site lies within the 100-year flood limits (Refer to the exhibits in the Appendix.)
Development of the site will be done in accordance with FEMA and City of Fort
Collins guidelines for construction within a floodplain. The floodway does not
encroach upon the site. All proposed construction and land uses will be in
accordance with the above guidelines.
FINAL DRAINAGE ANALYSIS
- LOT 2-
MULBERRY AND LEMAY CROSSINGS
FT COLLINS, COLORADO
CLC JOB NO.95.040
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ............................ 1
II. DRAINAGE BASINS AND SUB -BASINS ............................... 1
III. DRAINAGE DESIGN CRITERIA ...................................... 2
IV. DRAINAGE FACILITY DESIGN ...................................... 2
V. STORMWATER QUALITY CONTROL PLAN ............................ 3
VI. CONSTRUCTION ACTIVITIES STORMWATER MANAGEMENT PLAN ...... 3
VII. CONCLUSIONS .................................................. 3
VIII. REFERENCES ................................................... 4
APPENDIX A - HYDROLOGIC CALCULATIONS
APPENDIX B - INLET SIZING
APPENDIX C - HYDRAULIC CALCULATIONS - STORM SYSTEM B
APPENDIX D - HYDRAULIC CALCULATIONS - STORM SYSTEM C
APPENDIX E - REFERENCE MATERIALS
APPENDIX F - MISCELLANEOUS CONSTRUCTION DETAILS
APPENDIX G - EROSION AND SEDIMENTATION CONTROL
APPENDIX H - RIP -RAP CALCULATIONS
APPENDIX I - POND 2 VOLUME CALCULATIONS AND REVISED SWMM MODELS
APPENDIX J - CITY COMMENTS AND CONSULTANT RESPONSE
BACK POCKET - DRAINAGE PLAN
FINAL DRAINAGE ANALYSIS
- LOT 2-
MULBERRY AND LEMAY CROSSINGS
FT COLLINS, COLORADO
October 5, 1999
r. March 1, 2000
r. July 3, 2000
r. September 29, 2000
Prepared For:
Goldberg Properties
1120 Lincoln Street #1101
Denver, Colorado 80203
(303) 759-8000
Prepared By:
CLC Associates, Inc.
8480 East Orchard Road, #2000
Englewood, Colorado 8011.1
(303) 770-5600
'This final report for the drainage desi
prepared by me (or under m'1
City of Fort Collins Storm 11�
to comply with the provisi;
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Jeffrey A. Holley, P.E. ��I///t'Ir
State of Colorado Registration No.
For and on behalf of
CLC Associates, Inc.
of Lot 2, Mulberry and Lemay Crossings was
gision) in accordance with the provisions of
a "4nd Technical Criteria, and was designed
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