HomeMy WebLinkAboutFORT COLLINS JEEP - PDP - PDP170013 - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTFINAL DRAINAGE REPORT
Fort Collins Jeep Dealership
Fort Collins, Colorado
Project #PDP170013
September 8, 2017
PREPARED FOR:
Commercial Building Services
7561 S. Grant Street, Suite A-4
Littleton, CO 80122
Contact: Steve Morel
(303) 730-3001
PREPARED BY:
PARAGON ENGINEERING CONSULTANTS, INC.
7852 South Elati Street, Suite 106
Littleton, CO, CO. 80120
(303) 794-8604
Paragon Project No. 16-018
Paragon Engineering Consultants, Inc. Page 1
Table of Contents
I. GENERAL LOCATION AND DESCRIPTION............................................................. 2
A. Site Location .................................................................................................................... 2
B. Description of Property .................................................................................................... 3
C. Floodplain Submittal Requirements ................................................................................. 4
II. MAJOR DRAINAGE BASINS AND SUB-BASINS ...................................................... 4
A. Major Drainage Basins ..................................................................................................... 4
B. Sub-basins ........................................................................................................................ 4
III. DRAINAGE DESIGN CRITERIA .................................................................................. 5
A. Regulations ....................................................................................................................... 5
B. Directly Connected Impervious Area ............................................................................... 6
C. Development Criteria Reference and Constraints ............................................................ 6
D. Hydrologic Criteria .......................................................................................................... 6
E. Hydraulic Criteria ............................................................................................................. 6
F. Floodplain Regulations Compliance ................................................................................ 7
G. Modifications of Criteria .................................................................................................. 7
IV. DRAINAGE FACILITY DESIGN ................................................................................... 7
A. General Concept ............................................................................................................... 7
B. Specific Details ................................................................................................................ 7
V. CONCLUSIONS ................................................................................................................ 8
VI. REFERENCES ................................................................................................................... 8
Appendix A – Vicinity Map, Soils Map, Floodplain Checklist
Appendix B – Hydrologic Computations
Appendix C – Hydraulic Calculations
Paragon Engineering Consultants, Inc. Page 2
I. GENERAL LOCATION AND DESCRIPTION
A. Site Location
Fort Collins Jeep Dealership is located on a site currently containing 4.48 acres northwest of the
intersection of South Mason Street and West County Road 38 in the City of Fort Collins, Larimer
County, Colorado. The site lies in the Southeast ¼ of Section 35, Township 7 North, Range 69
West of the 5
th
Principal Meridian. It is bounded on the north by an existing car dealership
(Pedersen Volvo), on the east by South Mason Street with existing commercial development
beyond, on the south by existing West County Road 38, with existing educational development
beyond, and on the west by existing bus road, with railroad with existing railway, greenbelt and
residential area beyond.
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B. Description of Property
The existing site was built as a lumber yard, but has not been used for that purpose for some time.
Detention appears not to have been required for the site when it was built in 1974, as none is in
evidence.
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The current area of the site is 4.48 acres. However, South Mason Street is slated for “midtown”
redevelopment, and an additional 0.13 acres of additional right-of-way is being requested by the
City of Fort Collins to expand South Mason Street.
The main building of the site will remain (will be remodeled), with two areas of expansion, one
on the west side of the building, and one on the north. An outdoor lumber storage area on the east
side of the existing building will be removed, as well as a raised concrete loading dock on the west
side of the site and other concrete pad areas. The aging pavement on the site will be removed and
replaced. The proposed use is car dealership.
Soils on the site, according to USDA National Soil Conservation website, consist of Nunn clay
loam- Hydrologic Soil Type C (94% of site) with a small area of Altvan-Satanta loams (6%) –
Hydrologic Soil Type B, in the northeast corner of the site. Fort Collins Jeep Dealership is located
outside the 100-year floodplain, according to FEMA FIRM map panel 08069C1000F (Map Panel
Not Printed.)
C. Floodplain Submittal Requirements
Fort Collins Jeep Dealership is located outside the 100-year floodplain, according to FEMA FIRM
map panel 08069C1000F (Map Panel Not Printed). See “City of Fort Collins Floodplain Review
Checklist 50% Development Review Submittals” in Appendix A.
II. MAJOR DRAINAGE BASINS AND SUB-BASINS
A. Major Drainage Basins
The site is located within the Mail Creek Basin, a basin of approximately 1,676 acres in southwest
Fort Collins. To the east of the site is College Avenue, which runs north-south and consists of
commercial development along the length. The remainder of the basin consists of mixed-use
residential development. The basin generally drains west to east to the confluence of Mail Creek
and Fossil Creek, and ultimately to Fossil Creek Reservoir. (City of Fort Collins 2017)
B. Sub-basins
The current drainage pattern consists of a large shallow swale within the west parking area of the
site, which directs runoff south to W. County Road 38 via an existing sidewalk chase. The east
side of the site slopes to the east from the east side of the main building, towards South Mason
Street via a drive entrance located near the south end of the South Mason Street frontage. Both
streets drain to the intersection of South County Road 38, and South Mason Street to an existing
10’ Type R inlet located on the South Mason Street side of the intersection. This inlet will be
moved west approximately 7’ to be in line with the proposed street widening of South Mason
Street There is also a low area in the southwest corner of the site, with no apparent outlet.
Proposed Sub-basins
The proposed grading will follow a similar pattern. The entrance locations will both change. The
W. County Road 38 entrance will be reduced in width to accommodate a bus pullout proposed to
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be built immediately west of the drive (eliminating traffic hazard from buses stopping in the lane
of this busy street.)
The South Mason Street entrance will be moved approximately 300 feet north to near the northeast
corner of the site. The runoff which previously drained to the entrance will be re-routed to South
Mason Street with a small channel and chase section located near the southeast corner of the new
proposed parking lot.
A low area in the southwest corner of the site, with no apparent outlet, will be raised such that the
runoff can be directed to the sidewalk chase at the low point in the parking area east of the West
County Road 38 drive entrance.
Proposed Basin A (0.22 acres of pavement) sheet flows to a 2-foot wide concrete pan which directs
runoff to Bioretention Pond A.
Proposed Basin B (0.33 acres of pavement) sheet flows to a 2-foot wide concrete pan which directs
runoff to Bioretention Pond B.
Proposed Basin C (1.72 acres of pavement and roof) sheet flows to a 2-foot wide concrete pan
which directs runoff to Bioretention Pond C.
Proposed Basin D (0.15 acres of pavement) sheet flows to a 2-foot wide sidewalk chase which
directs runoff to the north flowline of West Harmony Road. Runoff then flows east to the relocated
Type R inlet at the NW corner of West Harmony Road and South Mason Street.
Proposed Basin E (0.39 acres of pavement and roof) sheet flows to a 2-foot wide sidewalk chase
which directs runoff to the west flowline of South Mason Street. Runoff the flows south to the
relocated Type R inlet at the NW corner of West Harmony Road and South Mason Street.
Proposed Basin F (0.42 acres of pavement and roof) sheet flows to a 2-foot wide sidewalk chase
which directs runoff to the west flowline of South Mason Street. Runoff the flows south to the
relocated Type R inlet at the NW corner of West Harmony Road and South Mason Street.
Proposed Basin G (0.56 acres of pavement and roof) sheet flows to a 2-foot wide sidewalk chase
which directs runoff to the north flowline of West Harmony Road. Runoff then flows east to the
relocated Type R inlet at the NW corner of West Harmony Road and South Mason Street.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
The design of the proposed stormwater management system was done in compliance with Fort
Collins Amendments to the Urban Drainage and Flood Control District, Urban Storm Drainage
Criteria Manual Volumes 1, 2 and 3. (UDFCD 2017)
When improvements are proposed to an existing developed site and there is an increase in
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impervious area greater than 1000 square feet, onsite detention is required. The existing site
impervious area is 158,473 square feet and the proposed impervious area is 159,188 resulting in a
net increase in impervious area of 715 square feet therefore detention is not required. Low Impact
Development (LID) requirements are required on all redeveloped property. 75% of all newly added
or modified impervious are must be treated by LID techniques. There is 122,865 square feet of
redeveloped area onsite and 75% of this area is 92,149 square feet or 2.12 acres. This area will be
treated with three onsite Rain Gardens aka Bioretention Ponds. The Bioretention Ponds will drain
to the 10’ Type R Inlet at the SE corner of the site via a common 6” HPDE outfall pipe.
B. Directly Connected Impervious Area
The existing site will be redeveloped with a minimum increase in Directly Connected Impervious
Area. The increase in impervious area is 715 square feet, a 0.45% increase.
C. Development Criteria Reference and Constraints
The existing site has no stormwater management infrastructure, and drains undetained off-site.
The proposed stormwater management improvements meet Low Impact Development
requirements and will improve water quality and impact.
D. Hydrologic Criteria
Design rainfall values from “Table RA-8 – City of Forst Collins Rainfall Intensity-Duration-
Frequency Table for Use with the Rational Method” were used for the design rainfall. (Fort Collins
2016)
The Rational Method was used to determine peak runoff from sub-basins A, B, and C, for which
the methodology and tables as presented in the Urban Storm Drainage Criteria Manual were used
to determine Rational “C” coefficients, and time of concentrations. Calculations can be found in
Appendix B of this report.
E. Hydraulic Criteria
The UDFCD spreadsheet titled “UD-Detention” (Version 3.07, February 2017) was used to
calculate both the required water quality capture volume for the three rain gardens and the
geometry of the rain gardens. In accordance with LID requirements, Water Quality will be
provided for 75% of the redeveloped area, 2.12 acres. The Water Quality Volume is calculated on
a per basin basis. The calculations can be found in Appendix C of this report.
Autodesk Hydroflow Express was used to calculate the sizing of the rain garden underdrain. The
calculation can be found in Appendix C of this report.
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F. Floodplain Regulations Compliance
Fort Collins Jeep Dealership is located outside the 100-year floodplain, according to FEMA FIRM
map panel 08069C1000F (Map Panel Not Printed). See “City of Fort Collins Floodplain Review
Checklist 50% Development Review Submittals” in Appendix A.
G. Modifications of Criteria
No modifications of the criteria are proposed.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
The general drainage concept is to capture 75% of the redeveloped impervious area and treat it by
LID techniques via rain gardens. Sub-basins A, B, and C have been designed to total this area.
Runoff will drain to these three rain gardens, where it will be treated. Treated water will discharge
via a 6” HPDE storm pipe to the existing storm sewer at West County Road 38 and South Mason
Street.
Sub-basins D, E, F, and G will not be detained or treated and will drain off-site.
B. Specific Details
Surface runoff from sub-basins A, B, and C will sheet flow over pavement to concrete pans, then
collect in rain garden bioretention BMPs. The rain gardens are individually sized to the water
quality capture volume (WQCV) of their associated basins.
The three rain garden bioretention BMPs will be constructed with an impermeable liner on the
bottom, a 4” slotted PVC under-drain pipe embedded in a 6” thick layer of CDOT Class B filter
material, and an 18” layer of filter media on top. The 4” under-drain will have 4” cleanouts to
provide maintenance access. A concrete outlet structure will have inlet(s) to receive discharge from
the under-drain pipe(s) to receive discharge from the WQCV and an inlet grate to receive discharge
in excess of the WQCV. A 6” HDPE outlet pipe will discharge from the outlet structure to a
proposed 10’ Type R Inlet at the intersection of West County Road 38 and South Mason Street.
The storm water will then discharge to the existing storm sewer via a proposed manhole
constructed on the existing storm sewer.
In accordance with the LID techniques pertinent to the site, only the WQCV must be detained and
treated, and only for 75% of the total redeveloped area. Runoff in excess of the WQCV will pond
and discharge into the outlet structure inlet grate. If the ponding capacity is exceeded, the runoff
discharge off-site to West County Road 38.
Sub-basins D, E, F, and G will not be detained or treated and will drain off-site. These areas do
not require detention or treatment, as the LID requirement is satisfied by the rain garden
bioretention BMPs for sub-basins A, B, and C. Sub-basins D and G will discharge to West County
Road 38 via a curb cut. Sub-basins E and F will discharge to South Mason Street via the driveway
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at the northeast corner of the site.
V. CONCLUSIONS
The stormwater management system for the site has been designed in compliance to the Fort
Collins Amendments to the Urban Storm Drainage Criteria Manual Volumes 1, 2, and 3. Low
Impact Development (LID) requirements were followed to determine BMP requirements.
The development of the site will increase the impervious area of the site from 158,473 square feet
to 159,188 square feet, an increase of 715 square feet. The stormwater management system will
capture and treat stormwater in accordance with the above criteria, and overall will improve the
water quality of stormwater and reduce the discharge off-site into the roadway.
VI. REFERENCES
1. City of Fort Collins, 2017. Mail Creek. Retrieved July 17, 2017, from
https://www.fcgov.com/utilities/what-we-do/stormwater/drainage-basins/mail-creek-
basin
2. Urban Drainage and Flood Control District (UDFCD). 2017. Drainage Criteria Manual,
Volumes 1, 2, & 3, Urban Drainage and Flood Control District.
3. City of Fort Collins, 2016. Fort Collins Amendments to the Urban Drinage and Flood
Control District Criteria Manual.
Appendix A – Vicinity Map, Soils Map, Floodplain Checklist
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
1/12/2017
Page 1 of 4
4485860 4485880 4485900 4485920 4485940 4485960 4485980 4486000 4486020 4486040 4486060
4485860 4485880 4485900 4485920 4485940 4485960 4485980 4486000 4486020 4486040 4486060
493170 493190 493210 493230 493250 493270 493290 493310
493170 493190 493210 493230 493250 493270 493290 493310
40° 31' 31'' N
105° 4' 50'' W
40° 31' 31'' N
105° 4' 44'' W
40° 31' 24'' N
105° 4' 50'' W
40° 31' 24'' N
105° 4' 44'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 45 90 180 270
Feet
0 10 20 40 60
Meters
Map Scale: 1:1,010 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
4 Altvan-Satanta loams, 3
to 9 percent slopes
B 0.2 5.0%
74 Nunn clay loam, 1 to 3
percent slopes
C 4.4 92.1%
75 Nunn clay loam, 3 to 5
percent slopes
C 0.1 2.8%
Totals for Area of Interest 4.7 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
1/12/2017
Page 3 of 4
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
1/12/2017
Page 4 of 4
City of Fort Collins Floodplain Review Checklist
50% Development Review Submittals
Instructions: Complete this checklist by marking all boxes that have been adequately
completed. Put an “NA” next to any items that are not applicable to this particular
submittal. Any boxes that are left blank and do not have an “NA” marked next to them
are considered incomplete.
Date of Review:_____________ Reviewer’s Name:____________________________
Plat Map
The following required items are on the plat:
100-year floodplain boundary
City
FEMA
Floodway boundary
City
FEMA
The benchmark number and elevation of benchmark
These items match the FIRM. (FEMA Basin)
These items match the Master Plan. (City Basin)
The benchmark number and elevation match with those published in the City of Fort
Collins benchmark system.
Site Plan
The following required items are on the site plan:
100-year floodplain boundary- FEMA and City
500-year floodplain boundary (if proposed structure is a “critical facility”
and a 500-year floodplain is mapped)
Floodway boundary
Erosion buffer zones
Restriction related to use (i.e. critical facility or no residential use of lower
floor if floodproofed mixed-use structure)
Drainage and/or Grading Plan (or a separate Floodplain Sheet if it is too cluttered on
Drainage and Grading Plan)
The following required items are on the drainage and/or grading plan:
100-year floodplain boundary- FEMA and City
500-year floodplain boundary (if proposed structure is a “critical facility”
and a 500-year floodplain is mapped)
Floodway boundary
Erosion buffer zones
Cross-section locations
BFE lines
Regulatory Flood Protection Elevation for individual lots or groups of lots
if structures are to be built in the floodplain.
The floodplain and floodway boundaries are in the correct location and labeled
properly.
The cross-section and BFE lines are in the correct location and labeled properly.
Elevations are referred to the appropriate datum:
FEMA basins – list in both NGVD 29 and NAVD 88
City basins – list only in NGVD 29
Floodway regulations have been met.
No fill in the floodway unless a hydraulic analysis shows “no-rise”.
No manufactured homes, except in an existing park, can be placed in the
floodway.
No changing a nonconforming non-residential or mixed use structure to a
residential structure.
Landscaping meets requirements for no encroachment in the floodway
without a hydraulic analysis to show “no-rise”.
No storage of materials or equipment.
Critical facilities regulations have been met:
100 year – No life safety, emergency response, or hazardous material
critical facilities
500 year Poudre – No life safety or emergency response critical facilities
Any items in the floodway that can float (Example: picnic tables, bike racks, etc.) are
noted as being anchored.
Erosion Buffer Zone requirements have been met:
Design of any allowed development minimizes disturbance to channel bed
and banks.
No structures allowed.
No additions to existing structures allowed.
Any fencing is split-rail design and break-away, but cabled. Must be
oriented parallel to general flow direction.
No detention or water quality ponds.
No bike or pedestrian paths or trails except as required to cross streams or
waterways.
Road, bicycle and pedestrian bridges must span erosion buffer zone.
No fill.
No outdoor storage of non-residential materials or equipment.
No driveways or parking areas.
No irrigated vegetation and non-native trees, grasses, or shrubs.
No utilities except as necessary to cross streams or waterways.
No grading or excavation except as required for permitted activities in
erosion buffer zone.
No construction traffic except as required for permitted activities in
erosion buffer zone.
Any construction in the erosion buffer zone shows that it will not impact
the channel stability.
Any necessary floodplain modeling has been submitted and approved. All modeling
must follow the City’s floodplain modeling guidelines.
Special Poudre River Regulations
Poudre River Floodway Regulations have been met.
No construction of new residential, non-residential or mixed-use
structures.
No redevelopment of residential, non-residential or mixed-use structures.
No additions to residential, non-residential or mixed-use structures.
No fill unless hydraulic analysis shows “no-rise”.
Poudre River floodplain regulations have been met
No construction of new residential or mixed-use structures
No additions to residential structures
No additions to mixed-use structures if there is an expansion in the
residential-use area of the structure.
No floatable materials on non-residential sites
Information Related to Structures in the Floodplain
The regulatory flood protection elevation shown on the plans is at least 2 ft above the
BFE for the Poudre River and at least 18” above the BFE for new development and
redevelopment, 6” above the BFE for additions, substantial improvement and
accessory structures for all other floodplains.
A note is on the plans that the lowest floor (including basement or crawl space) and
HVAC will be required to be elevated above the regulatory flood protection
elevation. Non-residential structures can be floodproofed instead of elevated to the
regulatory flood protection elevation.
A typical drawing detail is included for each foundation type proposed (slab-on-
grade, basement, crawl space) showing the elevation of the HVAC and lowest floor
elevation (which includes bottom of the basement or crawl space) relative to the BFE.
If garages are not going to be elevated to the regulatory flood protection elevation,
then a note is included stating the following requirements:
There shall be 1 square inch of venting for every 1 square foot of enclosed
area.
The bottom of the venting shall not be higher than 1 foot above grade.
The venting shall be on at least two sides, preferably on upstream and
downstream sides. (Does not have to be divided equally).
For manufactured homes, a note is included stating that all submittal requirements on
separate sheet titled “Installation of a Mobile Home Located in a Floodplain:
Submittal Requirements” shall be met.
A note is on the plans stating that a floodplain use permit will be required for each
structure and each site construction element (detention ponds, bike paths, parking
lots, utilities, etc.) in the floodplain.
A note is on the plans stating that a FEMA elevation or floodproofing certificate will
be completed and approved before the CO is issued for any structures in the
floodplain. This is required even if property is only in a City floodplain.
Drainage Report
The site is described as being in the floodplain. Floodplain name and if the floodplain
is a FEMA or City-designated is described. Any floodway or erosion buffer zones on
the site are described.
The FEMA FIRM panel # and date and/or the Master Plan information is cited.
A copy of the FIRM panel with the site location marked is included in the report.
If a floodplain modeling report has been submitted, that report is referenced. The
reason for the floodplain modeling report is described.
If a FEMA CLOMR or LOMR is going to be needed, the reason for the CLOMR or
LOMR is described.
If a FEMA LOMR is required after construction, this is stated in the report.
The location of the structures relative to the floodplain is described. If there is both a
FEMA and a City floodplain on the site, the location of the structures relative to both
is described.
The use of the structures is described. This is to determine if the structure is
residential, non-residential, or mixed-use. Also, structures in all 100- year and Poudre
River 500-year floodplains cannot be used as a critical facility. (See Chapter 10 of
City Code for definitions.)
The report describes how the development will be in compliance with the applicable
floodplain regulations (Chapter 10 of City Code). (Examples: elevation of lowest
floor above regulatory flood protection elevation, floodproofing, floodway
regulations, erosion buffer zone regulations, no-rise, etc.)
The type of foundation construction for the structures (i.e. slab-on-grade, crawl space,
basement, etc.) is discussed in the report.
The type of foundation matches with the details shown on the grading plan.
The report states that the lowest floor (including basement or crawl space) and HVAC
will be required to be elevated above the regulatory flood protection elevation. Non-
residential structures can be floodproofed instead of elevated to the regulatory flood
protection elevation.
If garages are not going to be elevated to the regulatory flood protection elevation,
then a note is included stating the following requirements:
There shall be 1 square inch of venting for every 1 square foot of enclosed
area.
There bottom of the venting shall not be higher than 1 foot above grade.
The venting shall be on at least two sides, preferably on upstream and
downstream sides. (Does not have to be divided equally).
If a non-residential structure is to be floodproofed, then a note is included stating that
all requirements on separate sheet titled “Floodproofing Guidelines” shall be met.
(Floodproofing guidelines can be obtained at http://fcgov.com/stormwater/pdf/fp-
floodproofing.pdf)
For manufactured homes, a note is included stating that all submittal requirements on
separate sheet titled “Installation of a Mobile Home Located in a Floodplain:
Submittal Requirements” shall be met. (Mobile Home guidelines can be obtained at
http://fcgov.com/stormwater/pdf/fp-mobilhome.pdf)
The report states that a floodplain use permit will be required for each structure and
each site construction element (detention ponds, bike paths, parking lots, utilities,
etc.) in the floodplain.
A note is in the report stating that a FEMA elevation or floodproofing certificate will
be completed and approved before the CO is issued.
In the compliance section, Chapter 10 of City Code is listed.
FEMA CLOMR Approval
If a FEMA CLOMR is required, the necessary modeling has been submitted and
approved by the City.
Additional Comments:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Updated 11/29/2007
Terms to Note
Lowest Floor Elevation – Elevation of the lowest floor of the lowest enclosed area
(including bottom of basement or crawlspace). This is not the same as finished floor. The
lowest floor should be distinguished from finished floor on plans and reports.
Regulatory Flood Protection Elevation – For all floodplains except the Poudre River, the
regulatory flood protection elevation is eighteen (18) inches above the base flood
elevation. For the Poudre River floodplain, the regulatory flood protection elevation is
twenty-four (24) inches above the base flood elevation. If there is both a FEMA and a
City BFE, the higher BFE should be used to determine the regulatory flood protection
elevation.
Additional floodplain terminology is defined in Chapter 10 of City Code.
NOTE: Issues specific to individual sites may arise that result in additional
requirements. These will be discussed during initial meetings with the applicant.
Appendix B – Hydrologic Computations
RUNOFF COEFFICIENTS - DEVELOPED
Fort Collins Jeep DATE:
16-018
TWD
TWD
Type D Soils
Historic / Open Space Roof Tract / Open Space Pavement
2-Yr Coeff. 0.95 0.20 0.95
5-YEAR Coeff. 0.95 0.20 0.95 Note: Runoff coefficients shown were obtained from City of Fort Collins
100-YEAR Coeff. 1.19 0.25 1.19 Stormwater Criteria Manual Amendments Table RO-11
Impervious 95% 10% 95%
Historic / Open Space Roof Tract / Open Space Pavement
Design Design Area Area Area Area Area
Basin Point (AC) (AC) (AC) (AC) (AC) CC2
CC5
CC100
% Imp.
A 1 0.000 0.005 0.215 0.22 0.93 0.93 1.17 93%
B 2 0.02 0.31 0.33 0.90 0.90 1.12 89%
C 3 0.35 0.11 1.25 1.72 0.90 0.90 1.13 89%
D 4 0.00
E 5 0.00
F 6 0.00
G 7 0.00
0.00 0.35 0.14 1.78 2.27 0.90 0.90 1.13 90%
0.0% 15.6% 6.2% 78.3% 100%
0.00 0.35 0.14 1.78 2.27 0.90 0.90 1.13 89.8%
0.0% 15.6% 6.2% 78.3% 0.0%
TOTAL STUDY AREA
SUBTOTAL FOR BASIN A
September 5, 2017
Type B Soils
PROJECT NUMBER:
CALCULATED BY:
CHECKED BY:
PROJECT NAME:
Fort Collins Jeep DATE:
16-018
TWD
TWD
FINAL
tc
DESIGN AREA C5
LENGTH SLOPE Ti
LENGTH SLOPE Cv
Land Surface VEL Tt
COMP. TOTAL tc=(L/180)+10 C10 C100
BASIN Ac Ft % Min. Ft. % fps Min. tc LENGTH Min. Min.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)
A 0.22 0.93 60 2.2% 1.8 105 0.42% 20.0 Paved Areas 1.3 1.4 3.2 165 10.9 5.0 0.93 1.17
B 0.33 0.90 70 2.4% 2.3 130 44.00% 20.0 Paved Areas 13.3 0.2 2.5 200 11.1 5.0 0.90 1.12
C 1.72 0.90 70 1.1% 3.0 350 0.68% 20.0 Paved Areas 1.7 3.5 6.5 420 12.3 6.5 0.90 1.13
STANDARD FORM SF-2 - DEVELOPED
tc CHECK
(URBANIZED BASINS)
PROJECT NAME:
PROJECT NUMBER:
DATA
INITIAL
TIME (Ti
)
TRAVEL TIME
(Tt
)
CALCULATED BY:
CHECKED BY:
Time of Concentration
SUB-BASIN
September 5, 2017
1 / 3
0 . 395 ( 1 . 1 ) 1 / 2
S
C L
Ti
= − T
L
V
t =
60
Fort Collins Jeep DATE:
16-018 P1 (1-Hour Rainfall) = 0.82
TWD
TWD
DESIGN
BASIN
AREA
(AC)
RUNOFF
COEFF C5
tc (min)
C*A(ac)
I
(in/hr)
Q
(cfs)
tc(min)
∑(C*A)
(ac)
I
(in/hr)
Q
(cfs)
SLOPE
(%)
STREET
FLOW(cfs)
DESIGN
FLOW(cfs)
SLOPE
(%)
PIPE
SIZE (in)
LENGTH
(ft)
VELOCITY
(fps)
tt
(min)
(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)
C 1.72 0.90 6.5 1.55 2.58 4.00
B 0.33 0.90 5.0
5.0 0.21 2.78 0.57
0.30 2.78 0.82
TOTAL RUNOFF STREET
STANDARD FORM SF-3 - DEVELOPED
STORM DRAINAGE DESIGN - RATIONAL METHOD 2-YEAR EVENT
PROJECT NAME: September 5, 2017
PROJECT NUMBER:
CALCULATED BY:
PIPE TRAVEL TIME REMARKS
(1)
A 0.22 0.93
CHECKED BY:
STORM LINE
DESIGN
POINT
DIRECT RUNOFF
Fort Collins Jeep DATE:
16-018 P1 (1-Hour Rainfall) = 1.10
TWD
TWD
DESIGN
BASIN
AREA
(AC)
RUNOFF
COEFF C5
tc (min)
C*A(ac)
I
(in/hr)
Q
(cfs)
tc(min)
∑(C*A)
(ac)
I
(in/hr)
Q
(cfs)
SLOPE
(%)
STREET
FLOW(cfs)
DESIGN
FLOW(cfs)
SLOPE
(%)
PIPE
SIZE (in)
LENGTH
(ft)
VELOCITY
(fps)
tt
(min)
(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)
B 0.33 0.90
STANDARD FORM SF-3 - DEVELOPED
STORM DRAINAGE DESIGN - RATIONAL METHOD 5-YEAR EVENT
PROJECT NAME: September 5, 2017
PROJECT NUMBER:
CALCULATED BY:
PIPE TRAVEL TIME REMARKS
CHECKED BY:
STORM LINE
DESIGN
POINT
DIRECT RUNOFF TOTAL RUNOFF STREET
0.93
16-022
5.0 0.21 3.73 0.77
5.0 0.30 3.73 1.10
A 0.22
C 1.72 0.90 6.5 1.55 3.46 5.37
Fort Collins Jeep DATE:
16-018 P1 (1-Hour Rainfall) = 2.86
TWD
TWD
DESIGN
BASIN
AREA
(AC)
RUNOFF
COEFF C100
tc (min)
C*A(ac)
I
(in/hr)
Q
(cfs)
tc(min)
∑(C*A)
(ac)
I
(in/hr)
Q
(cfs)
SLOPE
(%)
STREET
FLOW(cfs)
DESIGN
FLOW(cfs)
SLOPE
(%)
PIPE
SIZE (in)
LENGTH
(ft)
VELOCITY
(fps)
tt
(min)
(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)
CHECKED BY:
DESIGN
POINT
DIRECT RUNOFF TOTAL RUNOFF
C 1.72 1.13 6.5 1.94 9.01
5.0 0.26
STANDARD FORM SF-3 - DEVELOPED
STORM DRAINAGE DESIGN - RATIONAL METHOD 100-YEAR EVENT
PROJECT NAME: September 5, 2017
PROJECT NUMBER:
CALCULATED BY:
(1)
A 0.22 1.17
PIPE TRAVEL TIME REMARKS
9.70
STREET
2.49
B 0.33
17.45
1.12 5.0 0.37 9.70 3.59
Appendix C – Hydraulic Calculations
Project:
Basin ID:
Depth Increment = 0.1 ft
Required Volume Calculation Media Surface 0.00 33.7 6.2 210 0.005
Selected BMP Type = RG 0.10 33.7 6.2 210 0.005 21 0.000
Watershed Area = 0.22 acres 0.20 33.7 6.3 211 0.005 40 0.001
Watershed Length = 178 ft 0.30 33.7 6.3 212 0.005 61 0.001
Watershed Slope = 0.005 ft/ft 0.40 33.7 6.3 212 0.005 82 0.002
Watershed Imperviousness = 90.00% percent 0.50 33.7 6.3 213 0.005 104 0.002
Percentage Hydrologic Soil Group A = 0.0% percent 0.60 33.8 6.3 214 0.005 125 0.003
Percentage Hydrologic Soil Group B = 0.0% percent 0.70 33.8 6.3 214 0.005 146 0.003
Percentage Hydrologic Soil Groups C/D = 100.0% percent 0.80 33.8 6.4 215 0.005 168 0.004
Desired WQCV Drain Time = 12.0 hours 0.90 33.8 6.4 216 0.005 189 0.004
Location for 1-hr Rainfall Depths = User Input 1.00 33.8 6.4 216 0.005 211 0.005
Water Quality Capture Volume (WQCV) = 0.006 acre-feet 1.10 33.8 6.4 217 0.005 233 0.005
Excess Urban Runoff Volume (EURV) = 0.020 acre-feet 1.20 33.9 6.4 218 0.005 254 0.006
2-yr Runoff Volume (P1 = 0.99 in.) = 0.016 acre-feet 0.99 inches Zone 1 (WQCV) 1.20 33.9 6.4 218 0.005 257 0.006
5-yr Runoff Volume (P1 = 1.1 in.) = 0.019 acre-feet 1.10 inches 1.30 33.9 6.4 218 0.005 276 0.006
10-yr Runoff Volume (P1 = 1.4 in.) = 0.024 acre-feet 1.40 inches 1.40 33.9 6.5 219 0.005 298 0.007
25-yr Runoff Volume (P1 = 1.99 in.) = 0.035 acre-feet 1.99 inches 1.50 33.9 6.5 220 0.005 320 0.007
50-yr Runoff Volume (P1 = 2.15 in.) = 0.038 acre-feet 2.15 inches 1.60 33.9 6.5 220 0.005 342 0.008
100-yr Runoff Volume (P1 = 2.86 in.) = 0.052 acre-feet 2.86 inches 1.70 33.9 6.5 221 0.005 364 0.008
500-yr Runoff Volume (P1 = 3.89 in.) = 0.073 acre-feet 3.89 inches 1.80 34.0 6.5 222 0.005 386 0.009
Approximate 2-yr Detention Volume = 0.015 acre-feet 1.90 34.0 6.5 222 0.005 408 0.009
Approximate 5-yr Detention Volume = 0.017 acre-feet 2.00 34.0 6.6 223 0.005 431 0.010
Approximate 10-yr Detention Volume = 0.022 acre-feet 2.10 34.0 6.6 224 0.005 455 0.010
Approximate 25-yr Detention Volume = 0.029 acre-feet 2.20 34.0 6.6 225 0.005 478 0.011
Approximate 50-yr Detention Volume = 0.029 acre-feet 2.30 34.0 6.6 225 0.005 500 0.011
Approximate 100-yr Detention Volume = 0.035 acre-feet 2.40 34.1 6.6 226 0.005 523 0.012
2.50 34.1 6.6 227 0.005 545 0.013
Stage-Storage Calculation 2.60 34.1 6.7 227 0.005 568 0.013
Zone 1 Volume (WQCV) = 0.006 acre-feet
2.70 34.1 6.7 228 0.005 591 0.014
Select Zone 2 Storage Volume (Optional) = acre-feet
2.80 34.1 6.7 229 0.005 614 0.014
Select Zone 3 Storage Volume (Optional) = acre-feet
2.90 34.1 6.7 229 0.005 636 0.015
Total Detention Basin Volume = 0.006 acre-feet
3.00 34.2 6.7 230 0.005 659 0.015
Initial Surcharge Volume (ISV) = N/A ft^3
3.10 34.2 6.7 231 0.005 682 0.016
Initial Surcharge Depth (ISD) = N/A ft
3.20 34.2 6.8 231 0.005 706 0.016
Total Available Detention Depth (Htotal
) = 1.20 ft
3.30 34.2 6.8 232 0.005 729 0.017
Depth of Trickle Channel (HTC) = N/A ft
3.40 34.2 6.8 233 0.005 752 0.017
Slope of Trickle Channel (STC
) = N/A ft/ft
3.50 34.2 6.8 233 0.005 775 0.018
Slopes of Main Basin Sides (Smain
) = 0.0833 H:V Smain not typical.
3.60 34.3 6.8 234 0.005 799 0.018
Basin Length-to-Width Ratio (RL/W
) = 5.4 3.70 34.3 6.8 235 0.005 822 0.019
3.80 34.3 6.9 235 0.005 846 0.019
Initial Surcharge Area (AISV) = 0 ft^2
3.90 34.3 6.9 236 0.005 869 0.020
Surcharge Volume Length (LISV) = 0.0 ft
0 User Defined Stage-Area Boolean for Message
0 Equal Stage-Area Inputs Watershed L:W
1 CountA
0 Calc_S_TC
H_FLOOR
33.6556 L_FLOOR_OTHER
0.00 ISV 0.00 ISV
0.00 Floor 0.00 Floor
1.20 Zone 1 (WQCV) 1.20 Zone 1 (WQCV)
0.00 Zone 2 0.00 Zone 2
0.00 Zone 3 0.00 Zone 3
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
UD-Detention, Version 3.07 (February 2017)
0.015
0.030
0.045
0.060
0.005
0.010
0.015
0.020
Volume (ac-ft)
Area (acres)
0
100
200
300
400
0
10
20
30
40
0.00 2.50 5.00 7.50 10.00
Area (sq.ft.)
Length, Width (ft.)
Stage (ft)
Length (ft) Width (ft) Area (sq.ft.)
Bioretention Pond A.xlsm, Basin 9/8/2017, 10:08 AM
Project:
Basin ID:
Depth Increment = 0.1 ft
Required Volume Calculation Media Surface 0.00 69.5 4.5 313 0.007
Selected BMP Type = RG 0.10 69.5 4.5 314 0.007 31 0.001
Watershed Area = 0.33 acres 0.20 69.5 4.5 316 0.007 60 0.001
Watershed Length = 195 ft 0.30 69.5 4.6 317 0.007 91 0.002
Watershed Slope = 0.005 ft/ft 0.40 69.5 4.6 318 0.007 123 0.003
Watershed Imperviousness = 90.00% percent 0.50 69.5 4.6 319 0.007 155 0.004
Percentage Hydrologic Soil Group A = 0.0% percent 0.60 69.6 4.6 321 0.007 187 0.004
Percentage Hydrologic Soil Group B = 0.0% percent 0.70 69.6 4.6 322 0.007 219 0.005
Percentage Hydrologic Soil Groups C/D = 100.0% percent 0.80 69.6 4.6 323 0.007 251 0.006
Desired WQCV Drain Time = 12.0 hours 0.90 69.6 4.7 324 0.007 284 0.007
Location for 1-hr Rainfall Depths = User Input 1.00 69.6 4.7 325 0.007 316 0.007
Water Quality Capture Volume (WQCV) = 0.009 acre-feet 1.10 69.6 4.7 327 0.008 349 0.008
Excess Urban Runoff Volume (EURV) = 0.029 acre-feet 1.20 69.7 4.7 328 0.008 382 0.009
2-yr Runoff Volume (P1 = 0.99 in.) = 0.024 acre-feet 0.99 inches Zone 1 (WQCV) 1.20 69.7 4.7 328 0.008 385 0.009
5-yr Runoff Volume (P1 = 1.1 in.) = 0.028 acre-feet 1.10 inches 1.30 69.7 4.7 329 0.008 414 0.010
10-yr Runoff Volume (P1 = 1.4 in.) = 0.036 acre-feet 1.40 inches 1.40 69.7 4.7 330 0.008 447 0.010
25-yr Runoff Volume (P1 = 1.99 in.) = 0.053 acre-feet 1.99 inches 1.50 69.7 4.8 332 0.008 480 0.011
50-yr Runoff Volume (P1 = 2.15 in.) = 0.058 acre-feet 2.15 inches 1.60 69.7 4.8 333 0.008 514 0.012
100-yr Runoff Volume (P1 = 2.86 in.) = 0.078 acre-feet 2.86 inches 1.70 69.7 4.8 334 0.008 547 0.013
500-yr Runoff Volume (P1 = 3.87 in.) = 0.108 acre-feet 3.87 inches 1.80 69.8 4.8 335 0.008 581 0.013
Approximate 2-yr Detention Volume = 0.022 acre-feet 1.90 69.8 4.8 337 0.008 614 0.014
Approximate 5-yr Detention Volume = 0.026 acre-feet 2.00 69.8 4.8 338 0.008 648 0.015
Approximate 10-yr Detention Volume = 0.033 acre-feet 2.10 69.8 4.9 339 0.008 685 0.016
Approximate 25-yr Detention Volume = 0.044 acre-feet 2.20 69.8 4.9 340 0.008 719 0.017
Approximate 50-yr Detention Volume = 0.043 acre-feet 2.30 69.8 4.9 342 0.008 753 0.017
Approximate 100-yr Detention Volume = 0.053 acre-feet 2.40 69.9 4.9 343 0.008 787 0.018
2.50 69.9 4.9 344 0.008 822 0.019
Stage-Storage Calculation 2.60 69.9 4.9 345 0.008 856 0.020
Zone 1 Volume (WQCV) = 0.009 acre-feet
2.70 69.9 5.0 347 0.008 891 0.020
Select Zone 2 Storage Volume (Optional) = acre-feet
2.80 69.9 5.0 348 0.008 926 0.021
Select Zone 3 Storage Volume (Optional) = acre-feet
2.90 69.9 5.0 349 0.008 960 0.022
Total Detention Basin Volume = 0.009 acre-feet
3.00 70.0 5.0 350 0.008 995 0.023
Initial Surcharge Volume (ISV) = N/A ft^3
3.10 70.0 5.0 352 0.008 1,031 0.024
Initial Surcharge Depth (ISD) = N/A ft
3.20 70.0 5.0 353 0.008 1,066 0.024
Total Available Detention Depth (Htotal
) = 1.20 ft
3.30 70.0 5.1 354 0.008 1,101 0.025
Depth of Trickle Channel (HTC) = N/A ft
3.40 70.0 5.1 355 0.008 1,137 0.026
Slope of Trickle Channel (STC
) = N/A ft/ft
3.50 70.0 5.1 357 0.008 1,172 0.027
Slopes of Main Basin Sides (Smain
) = 0.0833 H:V Smain not typical.
3.60 70.1 5.1 358 0.008 1,208 0.028
Basin Length-to-Width Ratio (RL/W
) = 15.4 3.70 70.1 5.1 359 0.008 1,244 0.029
3.80 70.1 5.1 360 0.008 1,280 0.029
Initial Surcharge Area (AISV) = 0 ft^2
3.90 70.1 5.2 362 0.008 1,316 0.030
Surcharge Volume Length (LISV) = 0.0 ft
0 User Defined Stage-Area Boolean for Message
0 Equal Stage-Area Inputs Watershed L:W
1 CountA
0 Calc_S_TC
H_FLOOR
69.4549 L_FLOOR_OTHER
0.00 ISV 0.00 ISV
0.00 Floor 0.00 Floor
1.20 Zone 1 (WQCV) 1.20 Zone 1 (WQCV)
0.00 Zone 2 0.00 Zone 2
0.00 Zone 3 0.00 Zone 3
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
UD-Detention, Version 3.07 (February 2017)
0.025
0.050
0.075
0.100
0.005
0.010
0.015
0.020
Volume (ac-ft)
Area (acres)
0
200
400
600
800
0
20
40
60
80
0.00 2.50 5.00 7.50 10.00
Area (sq.ft.)
Length, Width (ft.)
Stage (ft)
Length (ft) Width (ft) Area (sq.ft.)
Bioretention Pond B.xlsm, Basin 9/8/2017, 10:09 AM
Project:
Basin ID:
Depth Increment = 0.1 ft
Required Volume Calculation Media Surface 0.00 176.2 8.6 1,507 0.035
Selected BMP Type = RG 0.10 176.2 8.6 1,510 0.035 151 0.003
Watershed Area = 1.57 acres 0.20 176.2 8.6 1,513 0.035 287 0.007
Watershed Length = 453 ft 0.30 176.2 8.6 1,516 0.035 438 0.010
Watershed Slope = 0.005 ft/ft 0.40 176.3 8.6 1,519 0.035 590 0.014
Watershed Imperviousness = 90.00% percent 0.50 176.3 8.6 1,522 0.035 742 0.017
Percentage Hydrologic Soil Group A = 0.0% percent 0.60 176.3 8.7 1,525 0.035 894 0.021
Percentage Hydrologic Soil Group B = 0.0% percent 0.70 176.3 8.7 1,528 0.035 1,047 0.024
Percentage Hydrologic Soil Groups C/D = 100.0% percent 0.80 176.3 8.7 1,531 0.035 1,200 0.028
Desired WQCV Drain Time = 12.0 hours 0.90 176.3 8.7 1,534 0.035 1,353 0.031
Location for 1-hr Rainfall Depths = Erie 1.00 176.4 8.7 1,537 0.035 1,507 0.035
Water Quality Capture Volume (WQCV) = 0.042 acre-feet 1.10 176.4 8.7 1,541 0.035 1,661 0.038
Excess Urban Runoff Volume (EURV) = 0.140 acre-feet 1.20 176.4 8.8 1,544 0.035 1,815 0.042
2-yr Runoff Volume (P1 = 0.99 in.) = 0.113 acre-feet 0.99 inches Zone 1 (WQCV) 1.20 176.4 8.8 1,544 0.035 1,831 0.042
5-yr Runoff Volume (P1 = 1.1 in.) = 0.133 acre-feet 1.10 inches 1.30 176.4 8.8 1,547 0.036 1,970 0.045
10-yr Runoff Volume (P1 = 1.4 in.) = 0.171 acre-feet 1.40 inches 1.40 176.4 8.8 1,550 0.036 2,124 0.049
25-yr Runoff Volume (P1 = 1.99 in.) = 0.251 acre-feet 1.99 inches 1.50 176.4 8.8 1,553 0.036 2,280 0.052
50-yr Runoff Volume (P1 = 2.15 in.) = 0.274 acre-feet 2.15 inches 1.60 176.5 8.8 1,556 0.036 2,435 0.056
100-yr Runoff Volume (P1 = 2.86 in.) = 0.373 acre-feet 2.86 inches 1.70 176.5 8.8 1,559 0.036 2,591 0.059
500-yr Runoff Volume (P1 = 3.89 in.) = 0.519 acre-feet inches 1.80 176.5 8.9 1,562 0.036 2,747 0.063
Approximate 2-yr Detention Volume = 0.106 acre-feet 1.90 176.5 8.9 1,565 0.036 2,903 0.067
Approximate 5-yr Detention Volume = 0.125 acre-feet 2.00 176.5 8.9 1,568 0.036 3,060 0.070
Approximate 10-yr Detention Volume = 0.158 acre-feet 2.10 176.5 8.9 1,572 0.036 3,233 0.074
Approximate 25-yr Detention Volume = 0.208 acre-feet 2.20 176.6 8.9 1,575 0.036 3,390 0.078
Approximate 50-yr Detention Volume = 0.204 acre-feet 2.30 176.6 8.9 1,578 0.036 3,548 0.081
Approximate 100-yr Detention Volume = 0.251 acre-feet 2.40 176.6 9.0 1,581 0.036 3,706 0.085
2.50 176.6 9.0 1,584 0.036 3,864 0.089
Stage-Storage Calculation 2.60 176.6 9.0 1,587 0.036 4,022 0.092
Zone 1 Volume (WQCV) = 0.042 acre-feet
2.70 176.6 9.0 1,590 0.037 4,181 0.096
Select Zone 2 Storage Volume (Optional) = acre-feet
2.80 176.7 9.0 1,593 0.037 4,340 0.100
Select Zone 3 Storage Volume (Optional) = acre-feet
2.90 176.7 9.0 1,596 0.037 4,500 0.103
Total Detention Basin Volume = 0.042 acre-feet
3.00 176.7 9.1 1,600 0.037 4,660 0.107
Initial Surcharge Volume (ISV) = N/A ft^3
3.10 176.7 9.1 1,603 0.037 4,820 0.111
Initial Surcharge Depth (ISD) = N/A ft
3.20 176.7 9.1 1,606 0.037 4,980 0.114
Total Available Detention Depth (Htotal
) = 1.20 ft
3.30 176.7 9.1 1,609 0.037 5,141 0.118
Depth of Trickle Channel (HTC
) = N/A ft
3.40 176.8 9.1 1,612 0.037 5,302 0.122
Slope of Trickle Channel (STC
) = N/A ft/ft
3.50 176.8 9.1 1,615 0.037 5,463 0.125
Slopes of Main Basin Sides (Smain
) = 0.0833 H:V Smain not typical.
3.60 176.8 9.2 1,618 0.037 5,625 0.129
Basin Length-to-Width Ratio (RL/W
) = 20.6 3.70 176.8 9.2 1,621 0.037 5,787 0.133
3.80 176.8 9.2 1,624 0.037 5,949 0.137
Initial Surcharge Area (AISV) = 0 ft^2
3.90 176.8 9.2 1,627 0.037 6,112 0.140
0 User Defined Stage-Area Boolean for Message
0 Equal Stage-Area Inputs Watershed L:W
1 CountA
0 Calc_S_TC
H_FLOOR
176.192 L_FLOOR_OTHER
0.00 ISV 0.00 ISV
0.00 Floor 0.00 Floor
1.20 Zone 1 (WQCV) 1.20 Zone 1 (WQCV)
0.00 Zone 2 0.00 Zone 2
0.00 Zone 3 0.00 Zone 3
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
UD-Detention, Version 3.07 (February 2017)
0.000
0.095
0.190
0.285
0.380
0.000
0.015
0.030
0.045
0.060
0.00 2.50 5.00 7.50 10.00
Volume (ac-ft)
Area (acres)
Stage (ft.)
Area (acres) Volume (ac-ft)
0
500
1000
1500
2000
0
45
90
135
180
0.00 2.50 5.00 7.50 10.00
Area (sq.ft.)
Length, Width (ft.)
Stage (ft)
Length (ft) Width (ft) Area (sq.ft.)
Bioretention Pond C.xlsm, Basin 9/8/2017, 10:09 AM
W W W W
S S S S S S S S S S S S S
M
S
S S
S S S S S
W W W W W W
X
X X
X
X
X
X
X
X X X
X
X X
X
X
SS
SS
S
S
S
S
S
S
W W W
W
W
W
W
W
W W
S S
S
S S S
W W W W W W W W
W W W W W
S
S
S
S S
X X X
X
X X X X
X
X X
X
X
X
X
X
X
X
X X X X X
ONLY
ONLY
.
.
.
.
.
.
.
.
.
.
.
.
.
.
..
.
....
.
..
..
..
....
.
....
...
....
.
..
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A
0.22 0.93
1.16
E
0.39 N/A
N/A
F
0.42 N/A
N/A
G
0.56 N/A
N/A
C
1.72 0.89
B 1.12
0.33 0.89
1.11
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D
0.15 N/A
N/A
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5045
5043
5044
5045
5044
5046
5045
5046
5047
5045
5044
5041
5042
5040
5045
5039
5041
5042
5043
5044
5045
5046
5047
5048
1
2
3
5045
5045
5043
5043
5044
5044
5046
5046
5040
5041
5042
4.44%
2.63%
3.13%
2.77%
1.56%
1.10%
1.63%
1.66%
4.51%
5045
5044
5045.54 FL
5045.01 FL
5044.49 FL
5044.42 FL
5043.76 FL
5044.12 FL
5043.59 FL
5043.3 FL
5043.48 FL
5043.7 FL
5043.9 FL
5043.4 FL
5043.96 FL
5044.63 FL
5044.05 FL
5044.18 FL
5042.37 FG
5041.74 FG
WQ RELEASE STRUCTURE
WQ RELEASE STRUCTURE
WQ RELEASE STRUCTURE
6" 90° BEND
6" - TEE
6"-90° BEND
6" CLEANOUT
6" - 11.25° Bend
6" - Tee and
6" - 11.25° Bend
15 LF~ 6" HDPE
100 LF~ 6" HDPE
100 LF~ 6" HDPE
113 LF~ 6" HDPE
30 LF~ 6" HDPE
8 LF~ 6" 6" HDPE PIPE
43 LF~ 6" HDPE 98 LF~ 6" HDPE
15 LF~ 6" HDPE
31 LF~ 6" HDPE
113 LF~ 6" HDPE
4" CLEANOUT
4" CLEANOUT
26 LF~ 4" A-2000 SLOTTED PIPE
90 LF~ 4" A-2000 SLOTTED PIPE 88 LF~ 4" A-2000 SLOTTED PIPE
62 LF~ 4" A-2000 SLOTTED PIPE
5047.2 EOA
5045.76 FL
5045.10 FL
5044.52 FL
5042.36 FL
5045.38 FG
5048.51 FG
5045.97 FL
5044.54 FL
5044.88 FG
5044.78 FL
5045.04 FL
5045.88 FG
5045.90 FG
18 LF~ 4" A-2000
SLOTTED PIPE
18 LF~ 4" A-2000
SLOTTED PIPE
WQ/BIORETENTION BASIN A
VOLUME REQUIRED =250 CF
VOLUME PROVIDED=250 CF
WQ/BIORETENTION BASIN B
VOLUME REQUIRED =250 CF
VOLUME PROVIDED=250 CF
WQ/BIORETENTION BASIN C
VOLUME REQUIRED =1831 CF
VOLUME PROVIDED=1870 CF
0.39%
0.04%
0.49%
0.50%
0.43%
0.46%
1.85%
1.59%
1.63%
1.67%
0.46%
0.42%
0.03%
1.26%
0.31% 0.37%
0.61%
1.03%
Runoff Analysis Data Table
Basin ID C2 C100 Q2 (cfs) Q100 (cfs)
A 0.93 1.16 0.69 2.48
B 0.89 1.11 0.99 3.56
C 0.89 1.12 4.78 17.25
PROPOSED 15' TYPE R INLET
PROPOSED 4' DIA. STORM MANHOLE
CONNECT AND OUTLET TO EXISTING STORM SEWER
EXISTING STORM SEWER
REVISIONS
DESIGN: SCALE:
DRAWN: PROJECT NO:
DATE:
SHEET
PARAGON ENGINEERING CONSULTANTS, INC.
LITTLETON, CO 80120 303-794-8604
7852 SOUTH ELATI STREET, SUITE 106
Know what'sbelow.
Call before you dig.
R FORT COLLINS JEEP DEALERSHIP
DRAINAGE PLAN
TWD 9/8/2017 1" = 30'
MSG 16-018
D1.0
1 SUBMIT TO CITY 07/17/2017
2 SUBMIT TO CITY 09/08/2017
Feet
0 30 60
INFORMATION
SHOWN IS
SUBJECT
TO CHANGE. NOT
FOR
CONSTRUCTION
DRAINAGE LEGEND
BASIN NAME
2yr C VALUE
BASIN ACREAGE 100yr C VALUE
5820
5820
EX. MAJOR CONTOUR
EX. MINOR CONTOUR
PR. MAJOR CONTOUR
PR. MINOR CONTOUR
PROPOSED BASIN BOUNDARY LINE
1
BASIN
AREA 2yr
100yr
PR. STORM
EX. STORM
BASIN LABEL
DESIGN POINT
F:\Jobs\2016 Projects\16-018 Fort Collins Jeep\Cadd\Sheet Sets\Drainage Plan\D01 DRAINAGE PLAN.dwg, 9/8/2017 10:50:08 AM
Surcharge Volume Length (LISV) = 0.0 ft
4.00 176.9 9.2 1,631 0.037 6,275 0.144
Surcharge Volume Width (WISV) = 0.0 ft
4.10 176.9 9.2 1,634 0.038 6,438 0.148
Depth of Basin Floor (HFLOOR) = 0.00 ft
4.20 176.9 9.3 1,637 0.038 6,601 0.152
Length of Basin Floor (LFLOOR) = 176.2 ft
4.30 176.9 9.3 1,640 0.038 6,765 0.155
Width of Basin Floor (WFLOOR) = 8.6 ft
4.40 176.9 9.3 1,643 0.038 6,929 0.159
Area of Basin Floor (AFLOOR) = 1,507 ft^2
4.50 176.9 9.3 1,646 0.038 7,094 0.163
Volume of Basin Floor (VFLOOR) = 0 ft^3
4.60 177.0 9.3 1,649 0.038 7,259 0.167
Depth of Main Basin (HMAIN) = 1.20 ft
4.70 177.0 9.3 1,652 0.038 7,424 0.170
Length of Main Basin (LMAIN) = 176.4 ft
4.80 177.0 9.4 1,655 0.038 7,589 0.174
Width of Main Basin (WMAIN) = 8.8 ft
4.90 177.0 9.4 1,658 0.038 7,755 0.178
Area of Main Basin (AMAIN) = 1,544 ft^2
5.00 177.0 9.4 1,662 0.038 7,921 0.182
Volume of Main Basin (VMAIN) = 1,831 ft^3
5.10 177.0 9.4 1,665 0.038 8,087 0.186
Calculated Total Basin Volume (Vtotal) = 0.042 acre-feet
5.20 177.1 9.4 1,668 0.038 8,254 0.189
5.30 177.1 9.4 1,671 0.038 8,421 0.193
5.40 177.1 9.5 1,674 0.038 8,588 0.197
5.50 177.1 9.5 1,677 0.039 8,755 0.201
5.60 177.1 9.5 1,680 0.039 8,923 0.205
5.70 177.1 9.5 1,683 0.039 9,091 0.209
5.80 177.2 9.5 1,686 0.039 9,260 0.213
5.90 177.2 9.5 1,690 0.039 9,429 0.216
6.00 177.2 9.6 1,693 0.039 9,598 0.220
6.10 177.2 9.6 1,696 0.039 9,767 0.224
6.20 177.2 9.6 1,699 0.039 9,937 0.228
6.30 177.2 9.6 1,702 0.039 10,107 0.232
6.40 177.3 9.6 1,705 0.039 10,277 0.236
6.50 177.3 9.6 1,708 0.039 10,448 0.240
6.60 177.3 9.7 1,711 0.039 10,619 0.244
6.70 177.3 9.7 1,714 0.039 10,790 0.248
6.80 177.3 9.7 1,718 0.039 10,962 0.252
6.90 177.3 9.7 1,721 0.040 11,134 0.256
7.00 177.4 9.7 1,724 0.040 11,306 0.260
7.10 177.4 9.7 1,727 0.040 11,479 0.264
7.20 177.4 9.8 1,730 0.040 11,651 0.267
7.30 177.4 9.8 1,733 0.040 11,825 0.271
7.40 177.4 9.8 1,736 0.040 11,998 0.275
7.50 177.4 9.8 1,739 0.040 12,172 0.279
7.60 177.5 9.8 1,742 0.040 12,346 0.283
7.70 177.5 9.8 1,746 0.040 12,520 0.287
7.80 177.5 9.9 1,749 0.040 12,695 0.291
7.90 177.5 9.9 1,752 0.040 12,870 0.295
8.00 177.5 9.9 1,755 0.040 13,045 0.299
8.10 177.5 9.9 1,758 0.040 13,221 0.304
8.20 177.6 9.9 1,761 0.040 13,397 0.308
8.30 177.6 9.9 1,764 0.041 13,573 0.312
8.40 177.6 10.0 1,767 0.041 13,750 0.316
8.50 177.6 10.0 1,771 0.041 13,927 0.320
8.60 177.6 10.0 1,774 0.041 14,104 0.324
8.70 177.6 10.0 1,777 0.041 14,282 0.328
8.80 177.7 10.0 1,780 0.041 14,459 0.332
8.90 177.7 10.0 1,783 0.041 14,638 0.336
9.00 177.7 10.1 1,786 0.041 14,816 0.340
9.10 177.7 10.1 1,789 0.041 14,995 0.344
9.20 177.7 10.1 1,792 0.041 15,174 0.348
9.30 177.7 10.1 1,796 0.041 15,353 0.352
9.40 177.8 10.1 1,799 0.041 15,533 0.357
9.50 177.8 10.1 1,802 0.041 15,713 0.361
9.60 177.8 10.2 1,805 0.041 15,893 0.365
9.70 177.8 10.2 1,808 0.042 16,074 0.369
Optional User Override
1-hr Precipitation
Total detention volume
is less than 100-year
volume.
Volume
(ft^3)
Volume
(ac-ft)
Area
(acre)
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
Optional
Override
Area (ft^2)
Length
(ft)
Optional
Override
Stage (ft)
Stage
(ft)
Stage - Storage
Description
Area
(ft^2)
Width
(ft)
16-018 Fort Collins Jeep
Bioretention Pond C
UD-Detention, Version 3.07 (February 2017)
Example Zone Configuration (Retention Pond)
Bioretention Pond C.xlsm, Basin 9/8/2017, 10:09 AM
4.00 70.1 5.2 363 0.008 1,352 0.031
Surcharge Volume Width (WISV) = 0.0 ft
4.10 70.1 5.2 364 0.008 1,389 0.032
Depth of Basin Floor (HFLOOR) = 0.00 ft
4.20 70.2 5.2 365 0.008 1,425 0.033
Length of Basin Floor (LFLOOR) = 69.5 ft
4.30 70.2 5.2 367 0.008 1,462 0.034
Width of Basin Floor (WFLOOR) = 4.5 ft
4.40 70.2 5.2 368 0.008 1,498 0.034
Area of Basin Floor (AFLOOR) = 313 ft^2
4.50 70.2 5.3 369 0.008 1,535 0.035
Volume of Basin Floor (VFLOOR) = 0 ft^3
4.60 70.2 5.3 371 0.009 1,572 0.036
Depth of Main Basin (HMAIN) = 1.20 ft
4.70 70.2 5.3 372 0.009 1,609 0.037
Length of Main Basin (LMAIN) = 69.7 ft
4.80 70.3 5.3 373 0.009 1,647 0.038
Width of Main Basin (WMAIN) = 4.7 ft
4.90 70.3 5.3 374 0.009 1,684 0.039
Area of Main Basin (AMAIN) = 328 ft^2
5.00 70.3 5.3 376 0.009 1,721 0.040
Volume of Main Basin (VMAIN) = 385 ft^3
5.10 70.3 5.4 377 0.009 1,759 0.040
Calculated Total Basin Volume (Vtotal) = 0.009 acre-feet
5.20 70.3 5.4 378 0.009 1,797 0.041
Optional User Override
1-hr Precipitation
Total detention volume
is less than 100-year
volume.
Volume
(ft^3)
Volume
(ac-ft)
Area
(acre)
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
Optional
Override
Area (ft^2)
Length
(ft)
Optional
Override
Stage (ft)
Stage
(ft)
Stage - Storage
Description
Area
(ft^2)
Width
(ft)
16-018 Fort Collins Jeep
Bioretention Pond B
UD-Detention, Version 3.07 (February 2017)
Example Zone Configuration (Retention Pond)
Bioretention Pond B.xlsm, Basin 9/8/2017, 10:09 AM
4.00 34.3 6.9 237 0.005 893 0.020
Surcharge Volume Width (WISV) = 0.0 ft
4.10 34.3 6.9 237 0.005 917 0.021
Depth of Basin Floor (HFLOOR) = 0.00 ft
4.20 34.4 6.9 238 0.005 940 0.022
Length of Basin Floor (LFLOOR) = 33.7 ft
4.30 34.4 6.9 239 0.005 964 0.022
Width of Basin Floor (WFLOOR) = 6.2 ft
4.40 34.4 7.0 240 0.005 988 0.023
Area of Basin Floor (AFLOOR) = 210 ft^2
4.50 34.4 7.0 240 0.006 1,012 0.023
Volume of Basin Floor (VFLOOR) = 0 ft^3
4.60 34.4 7.0 241 0.006 1,036 0.024
Depth of Main Basin (HMAIN) = 1.20 ft
4.70 34.4 7.0 242 0.006 1,060 0.024
Length of Main Basin (LMAIN) = 33.9 ft
4.80 34.5 7.0 242 0.006 1,084 0.025
Width of Main Basin (WMAIN) = 6.4 ft
4.90 34.5 7.0 243 0.006 1,109 0.025
Area of Main Basin (AMAIN) = 218 ft^2
5.00 34.5 7.1 244 0.006 1,133 0.026
Volume of Main Basin (VMAIN) = 257 ft^3
5.10 34.5 7.1 244 0.006 1,157 0.027
Calculated Total Basin Volume (Vtotal) = 0.006 acre-feet
5.20 34.5 7.1 245 0.006 1,182 0.027
Optional User Override
1-hr Precipitation
Total detention volume
is less than 100-year
volume.
Volume
(ft^3)
Volume
(ac-ft)
Area
(acre)
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
Optional
Override
Area (ft^2)
Length
(ft)
Optional
Override
Stage (ft)
Stage
(ft)
Stage - Storage
Description
Area
(ft^2)
Width
(ft)
16-018 Fort Collins Jeep
Bioretention Pond A
UD-Detention, Version 3.07 (February 2017)
Example Zone Configuration (Retention Pond)
Bioretention Pond A.xlsm, Basin 9/8/2017, 10:08 AM
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr
28, 2011
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
1/12/2017
Page 2 of 4