HomeMy WebLinkAboutBUCKING HORSE PARK - BDR210011 - SUBMITTAL DOCUMENTS - ROUND 3 - VARIANCE REQUEST
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Administrative Engineering Variance Request Letter
Date: March 9th, 2022
Project: Bucking Horse Park Project No. 1748-002
Fort Collins, Colorado
Attn: Heidi Hansen
Stormwater Development Review
City of Fort Collins
281 North College Avenue
Fort Collins, Colorado 80524
RE: Reduction of LID Requirements for Park
Dear Staff:
Promoting the health, safety, welfare, and property of the City of Fort Collins and citizens through
the proper control and treatment of stormwater, whether above or below surface; and, to ensure
uniformity in performance with respect to design and construction of all drainage facilities are
among the objectives of the Fort Collins Stormwater Criteria Manual (FCSCM) – as adopted by the
City Council of the City of Fort Collins, as referenced in Section 26-500 of the Code of the City
of Fort Collins December 2018. It is with those considerations in mind that this variance request
letter has been prepared. This letter is provided pursuant to Chapter 2 Section 8 of FCSCM to
document the site condition proposed to deviate from the current standards.
The criteria in question is the required amount of newly added or modified impervious area that
needs to be treated by a low impact development (LID) method. Impervious surfaces are defined
as hardscape surfaces that do not allow stormwater to infiltrate into the ground. Impervious
surfaces include asphalt, concrete, patios, and rooftops. The intent of LID, as described in the
FCSCM, is simply defined as an integrated, sustainable stormwater management program that
requires a disturbed, closer to the source stormwater runoff control that stimulate natural process
and relies mainly on filtration and infiltration to locally treat and manage stormwater runoff.
Therefore, LID measures are very effective at treating and promoting infiltration and filtration for
new developments that generate an increase in vehicular trips as well as greatly reduce the
existing impervious areas. The increase in vehicular usage and decrease in impervious area means
that additional pollutants such as magnesium chloride, salt, oil, gas, etc. all get generated on
these newly developed lots. Therefore, LID measures are essential for new commercial, multi-
family, and single-family developments to maintain the integrity of downstream infrastructure and
usage. However, a park does not generate these pollutants because there are no vehicles.
Therefore, Bucking Horse Park is seeking a variance request to reduce the required amount of
newly treated or modified impervious treated by formal LID measures. Chapter 7 Section 6 of the
FCSCM states that 50% of newly added or modified impervious areas must be treated by LID
measures.
Bucking Horse Park | Variance Request | 03.09.22
P:\1748-002\Admin\Varriance Request\VarianceRequest - LID Reduction.docx Page 2 of 2
Bucking Horse Park has been designed and graded in a way that promotes natural infiltration
within the large grass areas where a majority of all the runoff is being conveyed to. This natural
look and feel will add to the aesthetic and usability of the park for community members. The only
areas of the site that will not be conveying runoff via overland flow across large grass areas are
Basins 7 and 11 of the Bucking Horse Park Drainage Exhibit. However, these routing and grading
efforts taken to promote natural infiltration and filtration are not formal LID measures, but they do
promote infiltration and filtration of the minimal pollutants that will make their way onto the site.
To meet Land Use Code (LUC) requirements to some extent Bucking Horse Park is proposing to
install a single rain garden that treats runoff that is generated by the basketball court, ping-pong
court, and some concrete sidewalk near the northeast corner of the property which corresponds to
Drainage Basin 11 of the Bucking Horse Park Drainage Exhibit. Drainage Basin 11 makes up
27% of the sites total impervious area (i>=90%). Therefore, Bucking Horse Park would be
treating 27% of the total impervious through a formal LID measure which is 23% (50%-
27%=23%) less than required by Chapter 7 Section 6 of the FCSCM. The proposed alternative
design will not reduce the design life of the proposed park and will also reduce the footprint of LID
systems that take up useable and desirable space within the park for community members to
utilize. Therefore, I feel it is pragmatic to allow this reduction in standards because a park is
considered a “Low Intense Use” with negligible pollutant migration, and the proposed park is still
meeting the intent set forth by the Land Use Code with regards to LID requirements.
Sincerely,
Northern Engineering
Blaine Mathisen, PE
Project Engineer
Attachments:
- LID EXHIBIT
- DRAINAGE EXHIBIT
X
MILES
HOUSE
AVE
.
C.O.
STORM
DRAIN
(TYP.)
SWALE (TYP.)
RAIN GARDEN 11
FLAT AREA = 206 SQ. FT.
MIN. AREA = 146 SQ. FT.
LID EXHIBIT
RAIN GARDEN SUMMARY
FORT COLLINS, CO
BUCKING HORSE PARK
E N G I N E E R N GI
EHTRON R N
03.09.2022
P:\1748-002\DWG\DRNG\PARK\1748-002_PARK_LID-V2.DWG
NORTH
PROPOSED CONTOUR
PROPOSED STORM SEWER
PROPOSED SWALE
EXISTING CONTOUR
PROPOSED CURB & GUTTER
PROPOSED INLET
LID SUMMARY:
PROPERTY BOUNDARY
BASIN 11 RAIN GARDEN
NOTES
1.FOR LID AND RAIN GARDEN CALCULATIONS PLEASE
REFER TO THE DRAINAGE AND EROSION CONTROL
REPORT FOR BUCKING HORSE PARK DATED JAN. 19 2022.
2.REFER TO UTILITY PLANS FOR BUCKING HORSE PARK
FOR ADDITIONAL GRADING AND UTILITY INFORMATION.
3.REFER TO LANDSCAPE PLANS FOR ADDITIONAL
INFORMATION ON HARDSCAPES.
4.REFER TO DRAINAGE EXHIBIT SHEET ### OF UTILITY
PLANS FOR SOIL AMENDMENT NOTES
( IN FEET )
0
1 INCH = 100 FEET
100 100
BASIN 11 IMPERVIOUS (i>=90%) AREA
TREATED BY RAIN GARDE
Basin ID LID Treatment Impervious Area
(i%>=90%)(sq. ft.)
Impervious Area
Treated By LID
(sq. ft.)
Percent of Impervious
Treated by LID
11 Rain Garden 6781 6781 100%
Total Site 25492 6781 27%
LEGEND:
* TOTAL PERCENT IMPERVIOUS FOR ONSITE BASINS ONLY (i) = 13%