HomeMy WebLinkAbout612 E. PITKIN, CARRIAGE HOUSE - FDP - FDP160007 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTDrainage Memo
Date: October 23, 2015
Project: 612 Pitkin Street Project No. 1199-001
Fort Collins, CO
Attn: Stormwater Staff
City of Fort Collins Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
Stormwater Staff:
This letter serves to document the proposed drainage impacts of a new home proposed at 612 East
Pitkin Street in Fort Collins, Colorado.
Project Overview
The project as currently envisioned proposes to completely remove an existing 2-story home located
on the property and construct a new home as well as a carriage house that will be accessed from
the alley on the north side of the property.
Existing Site
The existing site functions as a “B” Lot, with drainage from the lot draining from the home out to
the side lot lines, which then convey the drainage to both the front and back of the lot. Existing
grades in the front yard range between 2%-4%, and grades in the back of the home vary between
1% and 2%. In addition to the existing home, the lot consists of a concrete driveway, concrete
entry walk and concrete porches around the entire home. The remainder of the site is Kentucky
Bluegrass lawn, with small landscaping beds and mature trees.
The total existing impervious area for the lot is 5,305 sf.
Proposed Site
The proposed site will continue to function as a ‘B’ Lot, with drainage from the new residence being
directed to the side lot lines, and then to both the front and back of the lot via existing “swales”
along the lot line. Existing grades outside of our improvements will remain unchanged, including
along the east side of the property where no improvements are proposed. Modifications to the
existing driveway and front entry walk are proposed with the new home, and a new carriage house
is proposed at the alley that will have a small concrete apron at the entrance.
The total proposed impervious area for the lot is 6,042 sf. This is an increase of 737 sf. The
increase in runoff as a result of this will be negligible, and no adverse impacts to adjacent properties
is anticipated.
Detention
Since the impervious area increases less than 1000 sf, no detention is required for the site.
Water Quality
Water Quality for the site is being provided by releasing concentrated flows from the roof into
landscaped areas that allow stormwater runoff to infiltrate surround soils. Stormwater that is
unable to infiltrate is slowly passed through vegetated areas, further removing stormwater
contaminates before stormwater leaves the property.
An exhibit has been provided to illustrate the existing and proposed impervious areas. Please feel
free to contact us if you have any questions.
Sincerely,
Andrew Reese
Project Engineering
Nicholas W. Haws, PE, LEED AP
Vice President
10.23.15