HomeMy WebLinkAboutDrainage Reports - 08/17/2021621SOUTHPARK DRIVE,SUITE 1600 LITTLETON,CO80120 - (720)252-3484 - FAX (303)979-1675
EMAIL:COLEH@HABERERGROUP.COM
1
HCI ENGINEERING
A division of
HABERER CARPENTRY INC.
July 8, 2021
Attn: Matt Simpson
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
Re: Drainage Conformance Letter for Lot 2, North College Marketplace Second Filing
______________________________________________________________________
Project Description
The following letter is written on behalf of North College Marketplace LLC to demonstrate that the proposed site
improvements are in conformance withthedrainage design outlined in the Approved North College Marketplace
Final Development Plan Drainage and Erosion Control Report 4/9/2009, prepared by Ayres Associates
h .
Lot 2 is 1.08 acres or 46,835 square feet. The existing site consists mostly of vacant land with natice vegetative
growth, with private drives on the west and south perimeter. The existing total impervious area within the limits
of site improvement changes is 2,005 square feet, or 0.05AC. (Impervious Area = 6.2%).
Proposed improvements will be performed on the majority of the site, except the private drive on the west side
of the site. Improvements will generally follow existing drainage patterns, and include construction of a new
building with associated utilities,sidewalks, parking and landscape areas. Improvements for The Site were largely
based on the approved Utility Plans for The North College
Marketplace Second Filing Ayres Associates.The proposed total impervious
area is 42,986 square feet, or 0.99 AC. (Impervious Area = 89.7%).
Sub-Basins
Report 1 shows the entire limits of this project within Basin P25 (4.51-AC, 83% Impervious). No sub-basins have
been delineated during the evaluation of this project. Lot 2 has been evaluated as both a portion of Basin P25,
and based on the previously approved site plan, both based on the existing lot lines to delineate the area.
Observations
The Site is part of the previously approved Report 1, more specifically a portion of Basin P25. The Site was first
evaluated to verify conformance with the impervious area of Basin P25. The Percent Impervious value of Basin
P25 is 83%, with the proposed site at 89.7%, a 6.7% increase. This discrepancy is believed to be due to large size
difference between Lot 2, and Basin P25 which includes some large perimeter pervious areas. With this in mind,
a comparison to the approved Site Plan for Lot 2 was made with the newly proposed improvements. The
approved Site Plan planned for a Percent Impervious value in Lot 2 of 90.3%, with the proposed site at 89.7%, a
0.6% decrease.
City of Fort Collins Approved Plans
Approved by:
Date:
621SOUTHPARK DRIVE,SUITE 1600 LITTLETON,CO80120 - (720)252-3484 - FAX (303)979-1675
EMAIL:COLEH@HABERERGROUP.COM
2
Conclusion
The proposed project has been analyzed utilizing the approved conditions set forth in Report 1. This drainage
letter and associated calculations are limited to the project shown by the attached Drainage Plan. Based on the
above findings and attached calculations HCI Engineering finds the proposed development to be in compliance
with the drainage criteria set forth in Report 1. No negative impacts are anticipated as a result of this
development to adjacent properties or downstream.
Sincerely,
T. Garrett Goodlin, P.E. - HCI Engineering
ATTACHMENTS
Soil Map and Properties
Excerpt from,North College Marketplace, Final Development Plan, Drainage and Erosion
Control Report
Excerpt from, Utility Plans for The North College Marketplace, Second Filing
Rational Calculations
o Runoff Coefficients and Percent Impervious
o Time of Concentration
o Direct Runoff 10-Yr Storm
o Direct Runoff 100-Yr Storm
o Direct Runoff Summary
Proposed Drainage Plan
This unofficial copy was downloaded on Dec-03-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Dec-03-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA