HomeMy WebLinkAboutBUCKINGHAM PLACE, 2ND FILING - PDP/FDP - FDP120019 - REPORTS - DRAINAGE REPORTApex EEEEnnnnggggiiiinnnneeeeeeeerrrriiiinnnngggg
908 Laporte Avenue ■ Fort Collins, Colorado 80521 ■ 970.219.2834
November 9, 2012
Mr. Glen Schleuter
Stormwater Department
City of Fort Collins Utilities
700 Wood Street
Fort Collins, CO 80521
RE: Preliminary Drainage Letter for Buckingham Place, Second Filing
APEX Project #45-104
Dear Glen,
We have prepared this initial preliminary drainage letter for Buckingham Place, Second Filing for
your review and approval.
The existing property is an undeveloped 12,529 square-foot lot on the east side of Third Street
approximately 200 lf north of Lincoln Avenue. It is in the Dry Creek Master Drainage This
project proposes to develop to single family residential lots on the property. The following is a
summary of the impacts to the drainage systems on and off the site. In addition, supporting
calculations and a drainage exhibit have been attached.
Runoff
The existing site (Basin EX) drains to the east and has 0.02 cfs and 0.78 cfs of runoff leaving the
site in the 2-year and 100-year storms, respectively. In the developed condition, approximately
0.17 acres drains to the west and 0.12 acres drains to the east. The area draining to the west is
defined as Basin A and will have 0.13 cfs and 0.87 cfs of runoff leaving the site in the 2-year and
100-year storms, respectively. The area draining to the east is defined as Basin B and will have
0.02 cfs and 0.41 cfs of runoff leaving the site in the 2-year and 100-year storms, respectively.
Detention Storage
The entire site is estimated to be approximately 50% to 60% impervious when built out. The
Dry Creek Master Drainage plan estimated this area at 90% impervious. Due to the reduction
in the planned imperviousness, the size of the site, and the difficulty in providing detention we
are not proposing any detention storage with this project.
Water Quality
The small site, location of the Coy Ditch, and proximity to adjacent storm sewer make it very
difficult to provide typical water quality. The residential site will have an area of non paved
surfaces at the front and rear of the lot. These areas will intercept the stormwater runoff that
comes from the roof, driveway, and patio areas and provide some water quality via
“disconnected impervious areas”. This is the extent of water quality that we are proposing.
Erosion Control
Erosion and Sediment Control devices will be implemented on the site as needed. It is
anticipated that onsite runoff will be contained by straw wattles surrounding the site. Inlet
protection will be placed adjacent to the inlet south of this site on 3rd Street.
Summary
Due to the size of this small site, the proposed development of the site will have minimal impact
to the stormwater r. The runoff from the site is less than what was originally planned for in the
Master Drainage Plan, therefore no on site detention or downstream improvements are
included with this project.
I appreciate your time and consideration in reviewing this submittal. Please contact me at 970-
217-7420 or seliason@bluesky-engineer.com if you have any questions.
Sincerely,
Samuel M. Eliason, P.E.
APEX Engineering
Attachments:
• Calculation of Peak Runoffs (EX 2-yr, EX 100-yr, A 2-yr, A-100 yr, B 2-yr, B 100-yr)
• Drainage Exhibit