HomeMy WebLinkAboutReports - Drainage - 01/08/2025
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com
Final Drainage Memorandum
For
300 E. Mountain Avenue
Dated: January 7, 2024
Fort Collins, Colorado
Developer
Mountain 300, LLC
1130 N. Alma School Road, Suite 120
Mesa, AZ 85201
o: 480.503.2250
f: 480.503.2258
Project No. 2102-001
Date: January 2025
EPS Group
Fort Collins | Greeley
970.221.4158
epsgroupinc.com
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com
January 8, 2025`
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage Memorandum for
300 E. Mountain Avenue
Dear Staff:
EPS Group is pleased to submit this Final Drainage Memorandum for your review. This memorandum accompanies the
Basic Development Review submittal for the proposed 300 E. Mountain Avenue.
This memorandum has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM), and serves to
document the stormwater impacts associated with the proposed project. We understand that review by the City is to
assure general compliance with standardized criteria contained in the FCSCM.
If you should have any questions as you review this memorandum, please feel free to contact us.
Sincerely,
EPS GROUP, INC.
Amber Ortiz Cragg, PE Blaine Mathisen, PE
Project Engineer Project Manager
ATTACHMENTS:
• Rational Calculations
• Sidewalk Chase Capacity Calculation
• Cash-In-Lieu LID Spreadsheet
• Existing and Proposed Drainage Exhibit – 300 E. Mountain Avenue
FINAL DRAINAGE MEMORANDUM
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com 3
GENERAL LOCATION AND DESCRIPTION
Figure 1: Vicinity Map
PROPERTY DESCRIPTION
The project Site of 300 East Mountain Avenue is located in the southwest quarter of Section 12, Township 7 North, Range
69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. The project Site is the
northeast corner lot at the intersection of Chestnut Street and Mountain Avenue.
The Site is currently composed of the remains of a demolished existing building and street parking. Existing ground slopes
are flat through the interior of the property. General topography slopes from south to north. As this is an infill site, the area
surrounding the site is fully developed.
According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil
Survey website: http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx, the site consists of Satanta loam (Hydrologic
Soil Group C).
The proposed project Site Plan is composed of the development of a new commercial building where the former Lyric used
to be. Associated site work includes the demolition of the existing building, which occurred in September 2024, and a
proposed new building within the same footprint. Sidewalk, curb and gutter will be replaced along the north and south
sides of the site to achieve sidewalk grades no steeper than 2% cross slope. Existing utility services will be utilized for the
proposed building.
The development area is roughly 0.2 net acres. This developed building is 0.09-acres and the improved area north the
building Site is 0.10-acre, while the improved area south of the building is 0.03-acre.
There are no known irrigation laterals crossing the site. The project site is not encroached by any City or FEMA designated
100-year floodplain. The Site can be found within the limits of FIRM Map 08069C0979H, Panel 979 of 1420, dated May 2,
2012.
FINAL DRAINAGE MEMORANDUM
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com 4
DRAINAGE BASINS
MAJOR BASIN DESCRIPTION
The project site lies within the Old Town Basin. Detention requirements for this basin are to detain the difference between
the 100-year developed inflow rate and the historic 2-year release rate if there is an increase in impervious area greater
than 5,000 square feet. The proposed project does not increase the impervious area by 5,000 square feet; therefore no
detention is required. The site building will have a roof drain connection along the Chestnut Street side where it will
discharge into a sidewalk chase. From there the runoff will enter the curb and gutter and flow north where it eventually is
captured by an inlet at the southeast corner of the Jefferson Street and Chestnut Street intersection. From there the runoff
is routed into the existing storm sewer system in Chestnut Street, which conveys flows into the Cache La Poudre River. The
subject property historically drains overland from northwest to southeast. Runoff from the site and adjacent paved areas
have historically been collected in existing inlets located within Chestnut Street and Mountain Ave.
It is not feasible to connect the roof drain to the existing 30” RCP Storm Sewer in Chestnut Street because of an existing
8” VCP Sanitary Sewer main as well as a 24”x30” concrete electrical duct bank that runs roughly 5”-11” below existing
grade near the lip of the east gutter. The electrical duct was potholed in December of 2024. Due to the vertical location
of these existing utilities running an 8” HP HDPE pipe from the downspout connection to the existing 30” RCP does not
allow us to meet minimum vertical separation. Additionally, it is not feasible to relocate the existing 24”x30” concrete
electrical duct.
DRAINAGE DESIGN CRITERIA
FOUR STEP PROCESS
The overall stormwater management strategy employed with the proposed project utilizes the “Four Step Process” to
minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed
development has incorporated each step.
Figure 2: Existing Site Conditions – Looking northeast
FINAL DRAINAGE MEMORANDUM
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com 5
Step 1 – Employ Runoff Reduction Practices
Techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and
pollutant loads as the site:
i. Conserving existing amenities at the site including the existing 4 mature trees within tree wells. Tree grates are
proposed for the existing 4 mature trees to provide protection from soil compaction.
ii. Proposed a new landscape area of 160 square feet with a new tree on the north side of the building. A tree grate will
provide protection from soil compaction.
Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release
The efforts taken in Step 1 will facilitate the reduction of runoff; however, urban development of this intensity will still
generate stormwater runoff that will require additional BMPs and water quality. With the constraints of this infill Site, WQCV
will be provided offsite at the discretion of the City of Fort Collins. The main constraint of the Site is the limited space to
accommodate WQCV that is outside of the right-of-way and outside of the building footprint. An additional constraint of
the Site is the limited ability to change elevations of the adjacent site hardscapes and the entry elevations of the proposed
building. City leadership discussed and agreed with the Applicant Team to waive LID requirements for this Site.
i. City Leadership discussed with the Applicant Team to waive LID requirements for this Site with the condition that the
Applicant include Cash-in-Lieu for LID requirements that can be used for larger regional projects. The value of $43,070
was calculated by the City of Fort Collins by completing a 50-year life cycle analysis using the 2017 Urban Drainages
(MHFD) model. The final cost to be paid by the Applicant will be inflated to 2025-dollar value. Refer to “Cash-in-Lieu”
spreadsheet that was provided by the City in the Appendix of this Memo.
Step 3 – Stabilize Streams
There are no streams or major drainageways within the subject property or directly adjacent to it. While this step may not
seem applicable to proposed development, the project indirectly helps achieve stabilized drainageways nonetheless by
providing funds as cash-in-lieu to the City for regional water quality control projects. Furthermore, this project will pay one-
time stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which help achieve City-
wide drainageway stability.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic conditions:
i. The trash enclosure will remain in the existing location for the Site which is away from Storm Inlets and offsite rain
gardens. Trash will be placed directly into the bins in the designated enclosure.
ii. During construction material storage areas will be placed away from Storm Inlets and offsite rain gardens.
HYDROLOGICAL CRITERIA
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure 3.4-1 of the FCSCM,
serve as the source for all hydrologic computations associated with the proposed development. Tabulated data
contained in Table 3.4-1 has been utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Table
3.2-2 of the FCSCM.
3. Three separate design storms have been utilized to address distinct drainage scenarios. The first event analyzed is
the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The second storm computed, for comparison
FINAL DRAINAGE MEMORANDUM
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com 6
purposes only, is the 10-year event. The third event considered is the “Major Storm,” which has a 100-year
recurrence interval.
4. No other assumptions or calculation methods have been used with this development that are not referenced by
current City of Fort Collins criteria.
MODIFICATIONS OF CRITERIA
This project Site proposed a variance to the LID requirement that will be approved by the Applicant providing Cash-in-
Lieu for City regional LID projects. Refer to the Cash-in-Lieu spreadsheet, that was prepared by the City, in the
Attachments for further clarification.
DRAINAGE FACILTY DESIGN
GENERAL CONCEPT
The main objectives of the project drainage design are to maintain existing drainage patterns, and to ensure no adverse
impacts to any adjacent properties.
Basin A1
Basin A1 consists of the new building that encompasses the extent of the Lot. The existing building has been removed and
a temporary asphalt layer has been placed on the surface. The proposed extents of the building and roof will match the
existing condition, having a 95% imperviousness for the basin. Drainage from the rooftop will be captured within a roof
drain system, which will be tied to a proposed 2’ sidewalk chase in Chestnut Street. In a major storm event, it is calculated
that 0.9-cfs will be collected from the rooftop and be conveyed through the proposed sidewalk chase to the existing
Chestnut Street curb and gutter where it will eventually be captured by an existing inlet at the intersection of Jefferson St
and Chestnut St. From there the runoff will be routed via the existing storm infrastructure to the Cache La Poudre River
Proposed hydraulic calculations with 100-year hydraulic grade line (HGL) are attached.
Basins A2
Basins A2 consists of a portion of the adjacent Right of Way of Chestnut Street to the north of the building that is being
rebuilt. This basin limit matches the extent of asphalt, curb, and sidewalk improvements to reconstruct sidewalk grades to
be 2% maximum cross slope. The existing flowline along the curb varies between surveyed points and appears to have a
section that is near 0.5% for approximately 40-ft between the existing trees adjacent to the Site. The sidewalk cross slope
varies between 3% and 5% towards the parking area and curb. Proposed improvements in this basin include sidewalk
reconstruction with a 2% maximum cross slope, 0.57% gutter flowline grade that brings up the curb and gutter about 3-
inches from existing grades. Stormwater continues to flow northeast along the curb and gutter to an existing inlet at the
corner of Chestnut Street and Jefferson Street where stormwater drains into the existing below ground storm pipe system.
In a major storm event, it is calculated that 1.0-cfs will be collected from this basin, the same flowrate as existing conditions.
Basins A3
Basins A3 consists of a portion of the adjacent Right of Way of Mountain Avenue to the south of the building that is being
rebuilt. This basin limit matches the extent of sidewalk improvements to reconstruct sidewalk grades to be 2% maximum
cross slope. The existing sidewalk cross slope varies between 2% and 3% towards the curb. Proposed improvements in this
basin include sidewalk reconstruction with a 2% maximum cross slope, bringing down the sidewalk down about 2-inches
from existing grades adjacent to the proposed building. Stormwater continues to sheet flow south from the sidewalk over
the curb into the gutter to an existing inlet at the corner of Mountain Avenue and Jefferson Street where stormwater drains
into the existing below ground storm pipe system. In a major storm event, it is calculated that 0.3-cfs will be collected from
this basin, the same flowrate as existing conditions.
Runoff computations for these basins based on the Rational Method and the Drainage Exhibit can be found at the end of
this memorandum.
FINAL DRAINAGE MEMORANDUM
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com 7
CONCLUSIONS
COMPLIANCE WITH STANDARDS
1. The drainage design proposed with the proposed project complies with the City of Fort Collins’ Stormwater
Criteria Manual.
2. The drainage design proposed with this project complies with requirements for the Old Town Basin.
3. The drainage plan and stormwater management measures proposed with the proposed development are
compliant with all applicable State and Federal regulations governing stormwater discharge.
DRAINAGE CONCEPT
1. The drainage design proposed with this project will effectively limit any potential damage associated with its
stormwater runoff by compliance with requirements set forth in current City master plans.
2. The drainage concept for the proposed development is consistent with requirements for the Old Town Basin and
the Downtown River District Final Design Report.
REFERENCES
1. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 159,
December 2018, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code.
2. Urban Storm Drainage Criteria Manual, Volumes 1 & 2, Urban Drainage and Flood Control District, Wright-
McLaughlin Engineers, Denver, Colorado, January 2016 and Partially Updated March 2024.
3. Urban Storm Drainage Criteria Manual, Volumes 3, Urban Drainage and Flood Control District, Wright-
McLaughlin Engineers, Denver, Colorado, November 2010 and Partially Updated March 2024.
ATTACHMENT
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com
RATIONAL CALCULATIONS
EPS Group
Runoff Coefficient1
Percent
Impervious1 Project:
Location:
0.10 2%Calc. By:
0.95 95%Date:
0.95 95%
0.00 0%
0.00 0%
0.00 0%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Lawns, Sandy Soil,
Flat Slope < 2%
(acres)
Asphalt, Concrete
(acres)Rooftop (acres)Percent
Impervious
C2*Cf
Cf = 1.00
C5*Cf
Cf = 1.00
C10*Cf
Cf = 1.00
C100*Cf
Cf = 1.25
A1 - Building 3,884 0.09 0.00 0.00 0.09 0.00 0.00 95%0.95 0.95 0.95 1.00
A2 - Chestnut Exist 4,533 0.10 0.00 0.10 0.00 0.00 0.00 94%0.94 0.94 0.94 1.00
A2 - Chestnut Proposed 4,533 0.10 0.01 0.10 0.00 0.00 0.00 90%0.91 0.91 0.91 1.00
A3 - Mountain 1,185 0.03 0.00 0.03 0.00 0.00 0.00 95%0.95 0.95 0.95 1.00
Lawns and Landscaping:
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).USDA SOIL TYPE: C
Composite Runoff Coefficient2
1) Runoff coefficients per Tables 3.2-1 & 3.2 of the FCSM. Percent impervious per Tables 4.1-2 & 4.1-3 of the FCSM.
DEVELOPED RUNOFF COEFFICIENT CALCULATIONS
Lawns, Sandy Soil, Flat Slope < 2%
Asphalt, Concrete
Rooftop
Streets, Parking Lots, Roofs, Alleys, and Drives:
Character of Surface:300 E. Mountain Ave
Fort Collins
Amber Ortiz Cragg
January 6, 2025
Page 1 of 1
EPS Group
Where:
Length
(ft)
Slope
(%)
Ti
2-Yr
(min)
Ti
10-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Slope
(%)Surface n
Flow
Area3
(sq.ft.)
WP3 (ft)R (ft)V
(ft/s)
Tt
(min)
Max.
Tc
(min)
Comp.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Comp.
Tc 100-
Yr
(min)
Tc
100-Yr
(min)
A1 A1 - Building 50 0.50%2.50 2.50 1.67 50 1.00%Gutter 0.035 3.61 19.18 0.19 1.40 0.60 10.56 3.09 5.00 3.09 5.00 2.26 5.00
A2 A2 - Chestnut Exist 18 3.00%0.89 0.89 0.55 120 0.60% Gutter 0.035 3.61 19.18 0.19 1.08 1.85 10.77 2.73 5.00 2.73 5.00 2.40 5.00
A2 A2 - Chestnut Proposed 18 3.00%1.05 1.05 0.55 120 0.60% Gutter 0.035 3.61 19.18 0.19 1.08 1.85 10.77 2.90 5.00 2.90 5.00 2.40 5.00
A3 A3 - Mountain 15 2.00%0.86 0.86 0.57 50 1.00% Gutter 0.035 3.61 19.18 0.19 1.40 0.60 10.36 1.46 5.00 1.46 5.00 1.17 5.00
Design
Point Basin ID
Overland Flow Channelized Flow Time of Concentration
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Location:
Maximum Tc:Overland Flow, Time of Concentration:
Channelized Flow, Velocity: Channelized Flow, Time of Concentration:
300 E. Mountain Ave
Fort Collins
Amber Ortiz Cragg
January 6, 2025
Project:
Calculations By:
Date:
Notes
S = Longitudinal Slope, feet/feet
R = Hydraulic Radius (feet)
n = Roughness Coefficient
V = Velocity (ft/sec) WP = Wetted Perimeter (ft)
(Equation 3.3-2 per Fort Collins =1.87 1.1 − ∗
=1.49
∗ /∗
(Equation 5-4 per Fort Collins
=
180 + 10 (Equation 3.3-5 per Fort Collins
Stormwater Manual)
=
∗ 60
(Equation 5-5 per Fort Collins
1) Add 4900 to all elevations.
2) Per Fort Collins Stormwater Manual, minimum Tc = 5 min.
3) Assume a water depth of 6" and a typical curb and gutter per
Larimer County Urban Street Standard Detail 701 for curb and gutter
channelized flow. Assume a water depth of 1', fixed side slopes, and a
triangular swale section for grass channelized flow. Assume a water
depth of 1', 4:1 side slopes, and a 2' wide valley pan for channelized
flow in a valley pan.
Page 1 of 1
EPS Group
Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100 Q2 Q10 Q100
A1 A1 - Building 0.09 5.0 5.0 5.0 1.0 1.0 1.0 2.9 4.9 10.0 0.2 0.4 0.9 108.3 185.1 398.2
A2 A2 - Chestnut Exist 0.10 5.0 5.0 5.0 0.9 0.9 1.0 2.9 4.9 10.0 0.3 0.5 1.0 124.9 213.5 464.7
A2 A2 - Chestnut Proposed 0.10 5.0 5.0 5.0 0.9 0.9 1.0 2.9 4.9 10.0 0.3 0.5 1.0 121.0 206.7 464.7
A3 A3 - Mountain 0.03 5.0 5.0 5.0 1.0 1.0 1.0 2.9 4.9 10.0 0.1 0.1 0.3 33.1 56.5 121.5
Flow (gpm)
DEVELOPED DIRECT RUNOFF COMPUTATIONS
Date:
Fort Collins
Project:
Location:
Calc. By:
Intensity (in/hr)Flow (cfs)
300 E. Mountain Ave
Amber Ortiz Cragg
January 6, 2025
Design
Point Basin
Intensity, I, from Fig. 3.4.1 Fort Collins Stormwater Manual.
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Area
(acres)
Runoff CTc (Min)
Page 1 of 1
ATTACHMENT
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com
SIDEWALK CHASE CALCULATIONS
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, Jan 7 2025
Sidewalk Chase
Rectangular
Bottom Width (ft) = 2.00
Total Depth (ft) = 0.50
Invert Elev (ft) = 1.00
Slope (%) = 1.90
N-Value = 0.013
Calculations
Compute by: Known Q
Known Q (cfs) = 0.89
Highlighted
Depth (ft) = 0.13
Q (cfs) = 0.890
Area (sqft) = 0.26
Velocity (ft/s) = 3.42
Wetted Perim (ft) = 2.26
Crit Depth, Yc (ft) = 0.19
Top Width (ft) = 2.00
EGL (ft) = 0.31
0 .5 1 1.5 2 2.5 3
Elev (ft)Depth (ft)Section
0.75 -0.25
1.00 0.00
1.25 0.25
1.50 0.50
1.75 0.75
2.00 1.00
Reach (ft)
ATTACHMENT
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com
CASH-IN-LIEU SPREADSHEET
This spreadsheet came from Nicole Poncelet-Johnson on December 23, 2024
Below is the email from Nicole with stated instructions:
The team completed a 50-year life cycle analysis using Urban Drainages (MHFD) model. Please see the estimated
“cash-in-lieu” amount and associated assumption (with more detail in the attached spreadsheet). We would be happy
to discuss the assumptions with your team. Note these funds would be used for larger regional projects, like the Oak
Street stormwater gardens or the wetland improvements that treat stormwater from downtown.
TOTAL: $43,070
The resulting costs are calculated in 2017 dollars, so an inflation factor will be needed to bring these to today’s dollars.
The cost of land is built into the capital cost calculation, so we did not utilize Real Estates estimate of $90/SF for land in
Old Town. We did not modify any of the parameters from the spreadsheet for rehabilitation, maintenance, or
administrative costs either. We felt that utilizing the default values may be the most straightforward approach.
Page 1/3
Project: 300 E. Mountain
Description:
*
*Note: E. coli reported in $/1012 cfu removed.
Totals
Summary of Average Annual Runoff Results
4,798 2,727 43%
Yes
8141
$6,288
#N/A
2,727
$550,200
Costs based on ENR CCI =
For Month/Year =
For Location =
0
Discharge to
Receiving Water
5.03E+08
0
$19,820
NPVC of Capital
Costs
76%
NPVC of
Administrative
Costs
NPVC of
Maintenance
Costs
NPVC of
Rehabilitation
Costs
$13,628
Peak Flow
Control
Summary of Net Present Value of Costs
Aug-09
DenverE. coli
1
Watershed
Runoff
4,798 43%
Runoff
Reduction
$3,334
D. Copper
TP
TN
Subcatchm
ent No.(ft3/yr)
0
D. Zinc
T. Zinc
0
0
0
2.07E+09
Other
(ft3/yr) (%)
0
0
UDFCD BMP-REALCOST Model
Results Worksheet
Summary of Water Quality Results
Constituent
Discharged
Pollutant Load
T. Copper 0
$50
($/lb)
TSS
0
1
0
23 77%
(lb/yr)
Pollutant
Reduction
Cost per Unit
Removed
Be sure to update report if changes
to model inputs have been made
TKN
$68,790
$1,670
0
Watershed
Pollutant Load
(lb/yr)
5
(%)
0
1
0
#N/A
62%
71%
53%
74%
$664,070
$892,900
25%
66%
36%
$393,440
$68,060
$2,740
All Costs for 50 years
$3,334$13,628 $6,288
Total NPVC $43,070
$19,820
Update Summary Report
Page 2/3
Project: 300 E. Mountain
Description:
Annual Runoff Volume Reduction Summary
UDFCD BMP-REALCOST Model
Results Worksheet
Summary of Watershed and Discharged Pollutant Loads
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
0
1
10
100
TSS TP TN TKN T. Zinc D. Zinc T. Copper D. Copper Other E. coli
An
n
u
a
l
E
c
o
l
i
C
o
u
n
t
(
#
)
An
n
u
a
l
P
o
l
l
u
t
a
n
t
L
o
a
d
(
l
b
)
Watershed Pollutant Loading Discharged Pollutant Loading
2,727
-
323
2,394
Total Runoff Discharged (CF)
Runoff Reduced due to Source Controls (CF)
Runoff Reduced due to BMPs (CF)
Page 1/2
Project:300 E. Mountain
Description:
Subcatchmen
t No. Subcatchment ID Area (ac) Land Use
Total
Imperviousn
ess (%)
Source
Control
(LID)
Effective
Impervious
ness (%)
NRCS
Soil Type
Subarea
Slope (%)
Effective
Runoff
Coefficient
1 1 0.09 Commercial 100% Level 0 100% C 1.00% 0.95
0.1 Area-Weighted
Imperviousness 100.00% 100.00% 0.95
Watershed Parameters
Watershed Summary
Total Area Area-Weighted
Runoff Coefficient
UDFCD BMP-REALCOST Model
Input Parameters Worksheet
Mean Storm Depth (in)
Default
Default
Project-Specific Precipitation and Cost Parameters
Planning Horizon (yrs)
Other
15.8
0.82
0.6
Buttons for Automating
Watershed Parameter Inputs
Default
Default
Current/Regional ENR CCI
Mean Annual Precipitation (in)
2-Year, 1-Hour Precipitation (in)
User-Entered
50 Default
Rate of Return (%)
Admin. Costs as % of Maint. (%)
Select Location for Precip. Values
Inflation Rate (%)4.60%
5.00%
12.00%
8141
Enter Default
Imperviousness Values
Calculate Runoff
Coefficients
Calculate Effective
Imperviousness
Restore
Default
Values
?
?
?
?
?
?
?
?
?
?
?
?
Import Inputs from another
workbook
Page 2/2
Project:300 E. Mountain
Description:
After entering all required information on the left, select whether you want to use regional-scale BMPs or local scale BMPs
Regional BMPs - Select the Regional BMP option button, then select a BMP from the drop-down box, then click on the "Calculate BMP Sizes" button
Subarea No.Area (ac)Regional BMP Selection WQCV/EURV (AF)BMP Size Units
Subarea No. Area (ac) Site BMP Selection
Total Impervious
Acres (IA) per BMP or
PP Run-on Area
PP Surface
Area (acres)
WQCV/EUR
V (AF) BMP Size Units
No. of
BMPs
1 0 Bioretention - Underdrain 0.09 0.00 0.00 182.34 CF 1
0.00 1Total Water Quality Control
Volume within watershed (Acre-
BMP Summary
Total # of BMPs
UDFCD BMP-REALCOST Model
Input Parameters Worksheet
Land Cost/ac
Local BMPs - Select the Local BMP option button, select a BMP for each subarea, enter the
number of impervious acres draining to each BMP, then click on the "Calculate BMP Sizes" button
Calculate BMP Sizes
Select Regional-Control BMP
Select Site-Control BMP
BMP-REALCOST
Best Management Practices – Rational Estimation of
Actual Likely Costs of Stormwater Treatment
A SPREADSHEET TOOL FOR EVALUATING BMP
EFFECTIVENESS AND LIFE CYCLE COSTS
User’s Manual and Documentation
Version 2.0
November 2017
Prepared by:
Chris Olson
Larry A. Roesner
Colorado State University
Department of Civil and Environmental Engineering
Fort Collins, CO 80523
Ben Urbonas
Urban Watersheds Research Institute
Denver, CO
Ken MacKenzie and Holly Piza
Urban Drainage Flood Control District
2480 West 26th Avenue
Suite 156-B
Denver, Colorado 80211
Jane Clary and Andrew Earles (2017 Update)
Wright Water Engineers, Inc.
2490 W. 26th Ave., Suite 100A
Denver, CO 80211
ATTACHMENT
Fort Collins | Greeley | (970) 221-4158 | epsgroupinc.com
MAP POCKET
X
VAULT
ELEC
ELEC
ELEC
TRAFFIC
VAULT
VAULT
ELEC
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
VAULT
ELEC
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ELE
C
BRK
R
G
F.O.
C.O.V.P.
CSCS
WV
WV
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MOUNTAIN AVENUE
SITE
CH
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S
T
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U
T
S
T
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E
E
T
(10
0
'
R
O
W
)
THE ARMORY BUILDING
CHESTNUT
STREET
ALLEY
A1
A2 A1
A2
A3
A3
ELI
Z
A
B
E
T
H
DO
W
N
T
O
W
N
H
O
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E
L
111
C
H
E
S
T
N
U
T
S
T
R
E
E
T
MOUNTAIN AVE.
334 E MOUNTAIN
AVENUE
THE ARMORY
314 E MOUNTAIN AVENUE
X
VAULT
ELEC
ELEC
ELEC
TRAFFIC
VAULT
VAULT
ELEC
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
VAULT
ELEC
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ELE
C
BRK
R
G
F.O.
C.O.V.P.
CSCS
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WV
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WV
G
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C
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ELEC
G
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.
VAU
L
T
S S
MOUNTAIN AVENUE
SITE
CH
E
S
T
N
U
T
S
T
R
E
E
T
(10
0
'
R
O
W
)
THE ARMORY BUILDING
CHESTNUT
STREET
ALLEY
A1
A2 A1
A2
PROPOSED ROOF
DRAIN CONNECTION
TO STORM LINE.
PROPOSED
LANDSCAPE
AREA
A3
A3
ELI
Z
A
B
E
T
H
DO
W
N
T
O
W
N
H
O
T
E
L
111
C
H
E
S
T
N
U
T
S
T
R
E
E
T
MOUNTAIN AVE.
334 E MOUNTAIN
AVENUE
THE ARMORY
314 E MOUNTAIN AVENUE
11
DR
A
I
N
A
G
E
E
X
H
I
B
I
T
NORTH
( IN FEET )
1 inch = ft.
Feet02020
20
40 60
LEGEND:
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
PROPOSED CONTOUR
EXISTING CONTOUR
PROPOSED CURB & GUTTER
PROPERTY BOUNDARY
A
DESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
NOTES:
1.EXISTING UNDERGROUND AND OVERHEAD PUBLIC AND PRIVATE UTILITIES AS
SHOWN ARE INDICATED ACCORDING TO THE BEST INFORMATION AVAILABLE TO
THE ENGINEER. THE ENGINEER DOES NOT GUARANTEE THE ACCURACY OF SUCH
INFORMATION. EXISTING UTILITY MAINS AND SERVICES MAY NOT BE STRAIGHT
LINES OR AS INDICATED ON THESE DRAWINGS. THE CONTRACTOR SHALL BE
RESPONSIBLE TO CALL ALL UTILITY COMPANIES (PUBLIC AND PRIVATE) PRIOR TO
ANY CONSTRUCTION TO VERIFY EXACT UTILITY LOCATIONS.
2.REFER TO THE 300 E MOUNTAIN AVENUE DRAINAGE MEMORANDUM FOR
ADDITIONAL INFORMATION.
3.EXISTING CONDITIONS ARE THE SAME AS PROPOSED CONDITIONS REGARDING
IMPERVIOUSNESS AND 100-YEAR STORM RELEASE RATES.
A
EXISTING CONDITIONS PROPOSED CONDITIONS
C2 C100 Q2
(cfs)
Q2
(gpm)
Q100
(cfs)
Q100
(gpm)
Sheet
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