HomeMy WebLinkAboutPARK SOUTH COMMERCIAL PLAZA, LOTS 3A THRU 3D - PDP - 37-94C - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT(3)
EROSION CONTROL:
The site is in the moderate rainfall erodibility zone and in the low wind erodibility zone. A
silt fence will be constructed along the South and East and North sides of the site. A straw bale dike
will be placed at the North end of the existing retention pond and at the Southwest corner of the
existing retention pond. A soil sealant will be applied to a part of the site.
The existing retention pond will provide the extended detention requirements for a forty hour
period for water quality treatment.
The grading, drainage and erosion control plan is enclosed as a part of this report. The
historic and developed runoff calculations are also a part of this report.
This drainage report and the design of the drainage system are in compliance with the City
of Fort Collins Storm Drainage specifications and criteria. If you have questions regarding this
report, please call.
Sincerely,
Richard A. Rutherford, P.E. & L.S.
RAR/meh
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$TEWARF&kSSOCIATES
IDecember 20, 2000 Consulting Engineers and Surveyors
Mr. Basil Harridan
Stormwater Utilities
City of Fort Collins
P.O. Box 580
Fort Collins, CO 80522-0580
Dear Basil,
The following is the Final Drainage Report for Lots 3A-D, Park South Commercial Plaza
Minor Subdivision, Second Filing, Fort Collins, Colorado. The site contains 4.4721 acres and is
located in the McClellands / Mail Creek Drainage Basin. The site is bounded on the West by
Manhattan Avenue, on the North by the access road to the Carmike Theatre, on the East by the
Carnuke Theatre site and on the South by Park South 2nd Filing P.U.D. which is a partially developed
apartment complex. The site is zoned C-Commercial.
The site slopes from Northwest to Southeast at an approximate slope of 1.5%. Part of the
existing retention pond for all of Park South Commercial Plaza is on Lots 3-C and 3-D. The channel
from the North side of the access road is in Lot 3-A. There is a stockpile of dirt on Lot 3-D that was
excavated from the retention pond.
The proposed development is a mini storage complex that has 15 buildings and an office
building. The site will be graded to carry the stormwater runoff to the existing retention pond in the
inverted crown driveways. The retention pond will have two times the volume of the difference
between the 100 year developed runoff rate and the two-year historic runoff rate.
The site is considered one historic drainage basin. The site will sheet flow from Manhattan
Drive to the existing drainage channel and to the existing retention pond. The two year historic rate
of runoff is 1.53 c.f.s. and the 100 year historic runoff rate is 6.84 c.f.s.
The developed site is divided into three sub -basins. D.B. I is the North 1.57 acres of the site
and its runoff enters at the North end of the retention pond. D.B. H is the middle of the site and
contains 1.69 acres. D.B. II will flow through D.B. III to the retention pond. D.B. III is the South
1.21 acres of the site. Its runoff enters the existing retention pond at the Southeast comer of the site.
The detention volume required for this site is 44,424 cubic feet and therefore the retention
volume required is 88,848 cubic feet.
The existing retention pond was enlarged in May of 1998 to accommodate the runoff from
Lots 2-B (Autawash) and this site which is Lots 3-A through 3-D of the Park South Commercial
Plaza Minor Subdivision Second Filing. The volume of retention for each of the lots was based on
a runoff coefficient of 0.75. The runoff coefficient for this site is 0.75. The runoff from this site was
calculated with the revised rainfall amounts.
I
James H. Stewart and Associates, Inc.
I 103 S. Meldrum Street • P.O. Box 429 • Ft. Collins, CO 80522
970/482-9331 • Fax 970/482-9382
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VICINITY MAP
SCALE: 1 "= 1000'
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TABLE OF CONTENTS
1
Vicinity Map
2-3
Text of Report
4-7
Runoff Calculations
S
Detention Pond Mass Diagram
9
Drainage Table
10-13
Erosion Control Calculations
Pocket
Grading, Drainage & Erosion Control
FINAL DRAINAGE PLAN FOR LOTS 3A-D
PARK SOUTH COMMERCIAL PLAZA MINOR SUBDIVISION SECOND FILING
McCLELLANDS / MAIL CREEK BASIN
PREPARED FOR BILLISIMO CONSTRUCTION INC.
DECEMBER 199 2000
PREPARED BY
STEWART & ASSOCIATES
103 SOUTH MELDRUM STREET
P.O. BOX 429
FORT COLLINS, CO 80522
TEL. 970-482-9331
FAX. 970-482-9382
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