HomeMy WebLinkAboutTHE GREEN SOLUTION - PDP/FDP - FDP150045 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTMEMO
To: Ryan Mounce, Project Planner
From: Julie Rentz
Date: December 16, 2015
Re: 810 N. College Avenue
Retail Marijuana Store and Cultivation Facility
The proposed project, located at 810 N College Avenue, City of Fort Collins, Larimer County, Colorado,
will expand an existing medical marijuana facility for use as a retail marijuana store.
The existing condition consists of an existing marijuana store and associated parking area. The existing
parking area located between the building and N. College Avenue will be removed and replaced
primarily with grass. A portion of the existing building and the asphalt to the east of the existing building
will be demolished for the construction of the building addition. The topography for the site generally
slopes from northwest to southeast at approximately 1.5%. Based on the USDA Web Soil Survey, the
soils within the site are clay loam which falls into Hydrologic Soils Group Type C. The landscaping on
site is primarily grass with a few trees to be planted in the reclaimed pervious areas throughout the site.
The proposed project will expand an existing medical marijuana facility for use as a retail marijuana
store. The current building, which has previously been expanded multiple times, is approximately 2,300
square feet. Although the project includes an approximate 2,500 sf building addition, the impervious
area for this project will decrease by approximately 3400 sf. The tributary drainage area for this site is
approximately 0.43 acres with a proposed limit of disturbance of approximately 0.35 acres.
Using the following equation from the Urban Drainage and Flood Control District Manual:
WQCV=a(0.91I3 – 1.19I2 + 0.78I)
Where:
a=1.0 (40 hour drain time)
I=0.77 (Composite Imperviousness)
WQCV=0.31 watershed-inches.
The required storage volume for the site is 485 cubic feet. This volume will be treated through the use of
an approved treatment BMP such as a rain garden or grass swale with a water quality structure located
on the south side of the proposed building. A final design will be prepared in accordance with the City of
Fort Collins Stormwater Criteria Manual.
All drainage facilities proposed with this project are private and will be maintained by the owner.