HomeMy WebLinkAboutOTTER BOX CORPORATE HEADQUARTERS (209 S. MELDRUM ST.) - FDP - 35-09/A - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTNORTHERN
ENGINEERING
Wes Lamarque
City of Fort Collins
700 Wood Street
ADDRESS: PHONE: 970.221.4158
200 S. College Ave. Suite 100 WEBSITE:
Fort Collins, CO80524 FAX:970.221.4159 Northern Engineering.com
Stormwater Utility
Fort Collins, Colorado 80521
March loth, 2010
Re: Final Drainage Report — OtterBox — New Headquarters
Dear Wes,
This letter is to summarize the drainage concepts for the proposed OtterBox
Building project located at 209 South Meldrum. More technically described as Lots 2 &
3 of Block 82 of the City of Fort Collins, County of Larimer, State of Colorado. The
project is located within the Old Town Master Drainage Basin.
The project will involve renovation and addition of the existing building located
at 209 S. Meldrum. Due to the current site conditions, a reconfiguration of the site has
been proposed. With the proposed construction, impervious area will be removed from
the site. Based on the Old Town Master Drainage Basin, and discussions that we have
had with you, as long as the additional imperviousness is less than 500 square feet,
detention is not required.
Existing and future percent imperviousness values for this basin are 84 percent
and 65 percent, respectively (please see Attachment #1). Based on our calculations, the
existing percent imperviousness for the overall property is 19 percent less than the
proposed site. Since the proposed percent imperviousness with the project is less than the
existing imperviousness, we conclude that detention is not required. Additionally, this
site is located in the Udall Natural Area which provides water quality treatment.
Historically, drainage from the site was divided to directed flows east and west.
As can be seen on the grading plan for the site, this drainage pattern is maintained with
the proposed construction. To achieve onsite water quality, both temporary and
permanent water quality measures have been included. The drainage entering the alley
has been routed through a bioretention swale and is released into the alley at the
southwest comer of the project site. This will lower the amount of pollutants entering the
existing storm system.
If you have any questions regarding drainage for this
contact me at 221-4158 ext. 133.
Sincerely,
THERN ENGINEERING
Bud Curtiss, P.E.
Senior Engineer
site, please do not hesitate to