HomeMy WebLinkAboutPROSPECT SPORTS CLUB - PDP230009 - DOCUMENT MARKUPS - ROUND 2 - VARIANCE REQUESTV ARIANCE R EQUEST
P ROSPECT S PORTS C LUB
F ORT C OLLINS ,CO
19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com
May 30, 2023
DAN MOGEN
700 WOOD STREET
FORT COLLINS,CO 80522
RE: STORMWATER VARIANCE REQUEST
PROSPECT SPORTS CLUB –1600 EAST PROSPECT ROAD
PROJECT NUMBER:U22014
Dan,
This letter is being submitted on behalf of the owners of the Prospect Sports Club development. The project is currently in
the Preliminary Development Plan process and currently one (1) variance is being requested to modify portions of the Fort
Collins Stormwater Criteria Manual as follows:
VARIANCE REQUEST –STORMWATER QUALITY AND LOW IMPACT DEVELOPMENT STANDARDS
DESIGN CRITERIA OF VARIANCE BEING REQUESTED
Section 1.0 within the Fort Collins Stormwater Criteria Manual which states:
FCU requires that water quality treatment systems for stormwater are installed for all applicable development sites,
including the incorporation of enhanced water quality treatment for stormwater, which has been required since 2013.
Section 6.0 within the Fort Collins Stormwater Criteria Manual which states:
Integration of LID systems into the drainage design is required for all development projects in order to comply with
the City’s policies on LID, the requirements of this Manual, the City Code and the Land Use Code. LID systems provide
a higher degree of stormwater quality treatment than that provided with standard water quality design. The
implementation of LID systems requires one of the following two options:
1)50% of the newly added or modified impervious area must be treated by LID techniques and 25% of new paved
(vehicle use) areas must be pervious.
2)75% of all newly added or modified impervious area must be treated by LID techniques.
HARDSHIP REGARDING REQUIREMENT
The site is located at 1600 East Prospect Road within Prospect Park East P.U.D and is surrounded by existing fully developed
commercial properties to the south (Advanced Energy) and west (Larimer County Coroner) along with Prospect Road and
Sharp Point to the north and east respectively. It should be noted that both properties (Advanced Energy and Larimer County
Coroner) are owned by the same entity and leased to these businesses.
The original subdivision development planned for drainage to be conveyed via overland flow to the drainage facility located
south of the site; therefore, no storm sewer currently exists on the site. The development team made numerous attempts
to negotiate with the property owner south of the Prospect Sports Club site to grant additional access on their site. The
additional access requests included:
An extension exiting access easement to provide access and emergency access to the western third of the Prospect
Sports Club site.
A shared parking agreement to alleviate potential on-site parking limitations.
V ARIANCE R EQUEST
P ROSPECT S PORTS C LUB
F ORT C OLLINS ,CO
19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com
After discussion with the south property owner and their attorney, the southern property owner has denied any new
easements on their property but will honor the existing access easement that allows for access, emergency access and limited
work within the easement. Thus, the site plan is arranged with the building to the east and the parking to the west accessed
from the existing easement. Additionally, storm sewer for the project will be required to convey both water quality and 100-
year developed stormwater flows from the site to the east of Sharp Point to the existing property also owned by the developer
of the basketball facility to avoid the need for drainage easements south of the site.
These site and storm sewer configurations generated by the design of the existing subdivision and the inability to modify the
southern property easements/agreements culminate into hardships with providing standard water quality and LID treatment
techniques that are approved by the City:
1.Standard water quality by way of extended detention is not viable due to space and grade limitations on the site.
Note that the open landscaped area north of the building is located within an existing pedestrian easement and is
also located on the high side of the property.
2.Underground detention/infiltration is not viable in the parking lot area due to available depths of storm sewer, is
not viable on the south or east due to the proximity of the proposed building to the property line and is likely not
viable on the north due to lack of access for maintenance.
3.Bioretention for the development is largely not viable due to the lack of space to provide the feature. Although
there is potentially room north of the building, the amount of impervious area that would drain to the area is limited
to small portions of hardscape due to grade limitations. Additionally, this area is located on the north side of the
building, during winter months it is probable that roof drainage if allowed to pond on frozen bioretention areas
would not infiltrate causing maintenance and safety concerns.
PROPOSED ALTERNATE DESIGN
The development team understands that water quality is an important aspect of every new development, not only to simply
meet City standards, but to protect downstream infrastructure and environments. Therefore, the design team is requesting
that the development, due to the hardships documented, is allowed to meet reduced or modified water quality and LID
treatment requirements and allowed to provide treatment techniques that differ from those typically allowed in the Fort
Collins Stormwater Criteria Manual. With that basis, the development team proposes to provide the following:
1.Provide grass lined swales and low points along the north side of the building within Basins A1 and A3 to provide,
albeit non-standard / non-quantitative, water quality treatment for limited hardscape to be located on the north
side of the building. These areas are then collected via storm sewer, conveyed through a water quality manhole
containing a Snout® and sump, and discharged to the privately owned wet pond to the east across Sharp Point.
These basins, being largely landscaped, will generate minimal pollutants on the site; however, are proposed to be
fully treated with multiple stages of treatment.
2.Provide permeable pavers within the parking lot as depicted in the Preliminary Development Plans. Approximately,
9,700 square-feet of permeable pavers are provided which is sufficient to treat the entirety of the parking lot and
plaza areas that drain to the pavers within Basins A4 and A5. The parking area will generate the most pollutants
from the site and will be fully treated with the paver system.
3.Conserve the existing low point located on the property to the south between the shared property line and the drive
lane to the south. This area exists and currently serves as a naturally vegetated area collecting stormwater runoff
with a maximum depth of approximately 12-inches. The design team proposes to allow only minor site areas
consisting of sidewalks and landscaped areas adjacent to the building and located within Basin OS2 to drain to this
existing low area acting as a vegetative buffer and infiltration treatment of runoff prior to allowing larger storm
events to overtop and drain via historic patterns to the detention facility south of the property.
4.Collect the proposed building roof drainage within Basin A2, designed to discharge towards the north and directly
into a proposed storm sewer system. Flows from this Basin are then conveyed through a water quality manhole
containing a Snout® and sump and discharged to the privately owned wet pond to the east across Sharp Point. This
basin, containing the entire roof area, will generate less pollutants than those expected in the parking area; however,
will be treated with multiple stages of treatment that will provide removal rates satisfying the State’s MS4 permit.
See the following section of this variance for additional detail regarding removal rates pertaining to this basin.
V ARIANCE R EQUEST
P ROSPECT S PORTS C LUB
F ORT C OLLINS ,CO
19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com
Per State of Colorado MS4 Permit requirements related to Basins A2 and A3 improvements, the following “Pollutant Removal
Standard” criterion is analyzed with this variance request: The control measure(s) is designed to treat at a minimum the 80th
percentile storm event. The control measure(s) shall be designed to treat stormwater runoff in a manner expected to reduce
the event mean concentration of total suspended solids (TSS) to a median value of 30 mg/L or less. A Nationwide Urban Runoff
Program (US EPA 1983) land use table regarding event mean concentrations is utilized for the purposes of measuring median
event mean concentrations of total suspended solids (TSS) assuming the site is included as an urban commercial
development. Per Table 4-1 of the EPA report, attached to this variance, a concentration of 69 mg/l is assumed for urban
commercial improvements.
Basins A2 and A3 are proposed to be treated first with a Snout located on the sports facility property and subsequently with
a private wet pond located on the owner’s property located east of Sharp Point. Per 3rd party performance testing, Snouts
provide a TSS pollutant removal rate ranging between 53%-85%. Per a National Pollutant Removal Performance Database, a
wet pond provides a removal rate for TSS pollutants of 80%. Documents regarding these removal rates can be found in the
Appendix of this Variance Request. Using these rates and a starting concentration of 69 mg/l, the Snout lowers TSS
concentrations to 32.4 mg/l assuming the most conservative removal rate of 53%. The subsequent treatment within the wet
pond provides for a final TSS concentration of 6.5 mg/l prior to allowing runoff being conveyed to the Poudre River.
As the vast majority of the proposed site is being treated for water quality and that the treatment techniques proposed are
either accepted by the City of Fort Collins or are shown within this variance to remove total suspended solids to levels
acceptable to the State of Colorado MS4 permit, the design team anticipates that the alternative compliance proposed with
this variance request will not have a negative impact on City infrastructure, downstream properties or the safety of the public.
On behalf of the owners of the Prospect Sports Club and the design team, we thank you for the consideration of this variance
request. If you should have any questions or comments regarding this request, please feel free to contact us at your
convenience.
Sincerely,
United Civil Design Group, LLC
Kevin Brazelton, PE
Principal
APPENDIX A – Referenced Materials
A PPENDIX A
R EFERENCED M ATERIALS
4 - 8
Table 4-1. Median Event Mean Concentrations for Urban Land Uses
Pollutant Units Residential Mixed Commercial Open/
Non-Urban
Median COV Median COV Median COV Median COV
BOD mg/l 10 0.41 7.8 0.52 9.3 0.31 ----
COD mg/l 73 0.55 65 0.58 57 0.39 40 0.78
TSS mg/l 101 0.96 67 1.14 69 0.85 70 2.92
Total Lead µg/l 144 0.75 114 1.35 104 0.68 30 1.52
Total Copper µg/l 33 0.99 27 1.32 29 0.81 ----
Total Zinc µg/l 135 0.84 154 0.78 226 1.07 195 0.66
Total Kjeldahl
Nitrogen
µg/l 1900 0.73 1288 0.50 1179 0.43 965 1.00
Nitrate +
Nitrite
µg/l 736 0.83 558 0.67 572 0.48 543 0.91
Total
Phosphorus
µg/l 383 0.69 263 0.75 201 0.67 121 1.66
Soluble
Phosphorus
µg/l 143 0.46 56 0.75 80 0.71 26 2.11
COV: Coefficient of variation
Source: Nationwide Urban Runoff Program (US EPA 1983)
Results from NURP indicate that there is not a significant difference in pollutant
concentrations in runoff from different urban land use categories. There is a significant difference,
however, in pollutant concentrations in runoff from urban sources than that produced from non-
urban areas.
The pollutants that are found in urban storm water runoff originate from a variety of
sources. The major sources include contaminants from residential and commercial areas, industrial
activities, construction, streets and parking lots, and atmospheric deposition. Contaminants
commonly found in storm water runoff and their likely sources are summarized in Table 4-2.
MD Office : Ph. (800) 504-8008 Fax (410) 687-6757 CT Office: Ph. (860) 434-0277 Fax (860) 434-3195
www.bmpi nc.com
DOCUMENTED 3rd PARTY PERFORMANCE:
Performance measured in multiple catch basins with SNOUT (drop inlets) over 2
year period in Peekskill, NY (Dutchess County) with flow to Peekskill Lake.
Mean TSS removals of 53% were recorded.1
Monitoring in Lower Makefield Twp., PA (Bucks County) with flow to Core Creek/
Lake Luxemburg of 9 SNOUT drop inlets show minimum TSS removals of 58%.2
Floatable Trash and Debris Removals with hooded catch basins in New York City
show average litter retention of 85%.3
ANECDOTAL PERFORMANCE MEASUREMENTS:
Multiple in line structures can improve solids removal performance and exceed
70% TSS removals. Various sites including Bryn Mawr Regional Stormwater
Facility, Bryn Mawr, PA
Removals of free oils can exceed 50%. Use of Bio-Skirts recommended for
longest term retention and 80%+ removals. Various sites around North America.
SOURCES:
1. Revised Restoration/Management Plan for Lake Luxembourg/CoreCreek
Watershed, Core Creek Park, Bucks County, Pennsylvania, Project No: 121.012
PA DEP, March 2005, (Princeton Hydro for Bucks County
Conservation District)
2. Structural Restoration Practices: A Collection of Successful Examples, F.
Lubnow, PhD, Princeton Hydro, February 2007
3. Combined Sewer Overflow Technology Fact Sheet Floatables Control
United States Environmental Protection Agency, Washington, D.C. EPA 832-
F99-008, September 1999