HomeMy WebLinkAboutDrainage Reports - 01/29/20217200 South Alton Way, Suite C400
Centennial, CO80112
303-740-9393 Fax 303-921-7320
130 East Kiowa Street, Suite 400
Colorado Springs, CO80903
719-593-2593 Fax 303-921-7320
2900 South College Avenue, Suite 3D
Fort Collins, CO80525
970-491-9888 Fax 303-921-7320
M EMORANDUM
JR Engineering, LLC has completed a weighted imperviousness based storm drainage evaluation for
the High Top Cultivation Facility. The following is a summary of the findings and determinations
made while performing an analysis of the proposed emergency access paving addition, concrete
mechanical pad, and sidewalk. It is important to note three things while reviewing this memo. First,
we believe that this project will not be required to provide a full drainage report, water quality or
detention facilities, based on the proposed site condition having a net reduction in impervious area
from the sites existing condition. Second, this analysis has been performed using a “weighted
impervious area” calculation, which is the square footage of each impervious surface type, multiplied
by the surfaces weighted impervious coefficient values for infiltration characteristics of different
materials (< 1). The impervious coefficient values were derived from the City of Fort Collins
Stormwater Criteria Manual Table 4.1-3 “Surface type – Percent Impervious”. Lastly, the High Top
Cultivation Facility site area’s drainage pattern was originally included in the “Stormwater & Erosion
Control Report for Kindcare” prepared by Forbes Engineering and approved by the City of Fort
Collins September 26, 2016. The “Proposed Impervious Area Exhibit” and “Proposed Drainage Sub-
Basins” maps from the original report can be referenced in Appendix C.
The High Top Cultivation Facility project site is located along the west side of South College Avenue
and south of West Trilby Road as seen on the vicinity map in Appendix A. The property currently
supports an existing metal building, which covers an approximate footprint of 18,270 sf. Just south of
the building lies an existing asphalt parking area and a vacant earth/gravel area to the west. The site is
composed primarily of type C soils and generally, slopes from 0 to 2 percent towards the lot’s eastern
property line. A specific breakdown of weighted impervious areas that compares existing areas to
proposed improvement areas can be found on the “Impervious Area Exhibit” within Appendix C. All
flows generated in the existing condition can be found in the “Stormwater & Erosion Control Report
for Kindcare” as previously mentioned.
The proposed improvements will include the addition of 5,578 sf of concrete/asphalt area and the
removal of 842 sf of existing asphalt for landscape planters. The proposed improvements are
composed of the addition of 2,390 sf of asphalt surface for emergency access, replacing a portion of
existing parking with landscape planters and sidewalk, the addition of 869 sf concrete mechanical pad,
2,319sf of sidewalk, and removal of the on-site gravel area to be replaced with seed and landscaping.
To: Mr. Wes Lamarque, PE
From: Tim Halopoff, PE, CFM
Date: Jan 6, 2021
Subject:High Top Cultivation Facility – Weighted Impervious Drainage Analysis
City of Fort Collins Approved Plans
Approved by:
Date:
Wes Lamarque
1/29/2021
7200 South Alton Way, Suite C400
Centennial, CO80112
303-740-9393 Fax 303-921-7320
130 East Kiowa Street, Suite 400
Colorado Springs, CO80903
719-593-2593 Fax 303-921-7320
2900 South College Avenue, Suite 3D
Fort Collins, CO80525
970-491-9888 Fax 303-921-7320
Appendix A
7200 South Alton Way, Suite C400
Centennial, CO80112
303-740-9393 Fax 303-921-7320
130 East Kiowa Street, Suite 400
Colorado Springs, CO80903
719-593-2593 Fax 303-921-7320
2900 South College Avenue, Suite 3D
Fort Collins, CO80525
970-491-9888 Fax 303-921-7320
Appendix B
7200 South Alton Way, Suite C400
Centennial, CO80112
303-740-9393 Fax 303-921-7320
130 East Kiowa Street, Suite 400
Colorado Springs, CO80903
719-593-2593 Fax 303-921-7320
2900 South College Avenue, Suite 3D
Fort Collins, CO80525
970-491-9888 Fax 303-921-7320
Appendix C
A Westrian Company
HIGH TOP CULTIVATION FACILITY
BASIC DEVELOPMENT REVIEW
IMPERVIOUS AREA EXHIBIT
X:\3970000.all\3978300\Drawings\Presentations\3978300 Impervious Exhibit.dwg, BDR Site Plan, 6/12/2020 9:32:15 AM, FC
This unofficial copy was downloaded on Jan-10-2020 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 Jan-10-2020 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
7200 South Alton Way, Suite C400
Centennial, CO80112
303-740-9393 Fax 303-921-7320
130 East Kiowa Street, Suite 400
Colorado Springs, CO80903
719-593-2593 Fax 303-921-7320
2900 South College Avenue, Suite 3D
Fort Collins, CO80525
970-491-9888 Fax 303-921-7320
Appendix D
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Sheet 1 of 1
Designer:
Company:
Date:
Project:
Location:
1. Design Discharge
A) 2-Year Peak Flow Rate of the Area Draining to the Grass Buffer Q2 =0.7 cfs
2.Minimum Width of Grass Buffer WG =14 ft
3.Length of Grass Buffer (14' or greater recommended)LG =229 ft
4.Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft)SG =0.020 ft / ft
5. Flow Characteristics (sheet or concentrated)
A) Does runoff flow into the grass buffer across the
entire width of the buffer?
B) Watershed Flow Length FL=50 ft
C) Interface Slope (normal to flow)SI=0.014 ft / ft
D) Type of Flow SHEET FLOW
Sheet Flow: FL * SI < 1
Concentrated Flow: FL * SI > 1
6. Flow Distribution for Concentrated Flows
7 Soil Preparation
(Describe soil amendment)
8 Vegetation (Check the type used or describe "Other")
9. Irrigation
(*Select None if existing buffer area has 80% vegetation
AND will not be disturbed during construction.)
10. Outflow Collection (Check the type used or describe "Other")
Notes:
Design Procedure Form: Grass Buffer (GB)
AJH
JR Engineering
High Top Cultivation Facility
June 9, 2020
UD-BMP (Version 3.07, March 2018)
Fort Collins
Existing Xeric Turf Grass
Irrigated Turf Grass
Other (Explain):
Choose One
Choose OneGrass Swale
Street Gutter
Storm Sewer Inlet
Other (Explain):
None (sheet flow)
Slotted Curbing
Level Spreader
Choose One
Other (Explain):
Choose OneYes No
Choose One
Permanent
None*
Temporary
UD-BMP_v3.07 (1).xlsm, GB 6/9/2020, 8:57 AM