HomeMy WebLinkAboutTRAILHEAD NEIGHBORHOOD PARK - BDR200002 - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTDRAINAGE REPORT
FOR
TRAIL HEAD PARK
AT
3403 YULE TRAIL DR
FORT COLLINS, CO 80524
PREPARED FOR
THE CITY OF FORT COLLINS
Fort Collins, CO 80523
MAY 5, 2020
Trail Head Park Final Drainage Report
Page 1 of 7
TABLE OF CONTENTS
GENERAL LOCATION AND EXISTING SITE INFORMATION .......................................................... 3
DRAINAGE BASINS AND HISTORIC RUNOFF ........................................................................... 4
HISTORIC DRAINAGE ....................................................................................................... 4
PROPOSED DRAINAGE .................................................................................................... 4
DRAINAGE DESIGN CRITERIA .............................................................................................. 5
HYDROLOGIC METHOD AND DESIGN STORM FREQUENCIES .................................................. 5
HYDRAULIC CRITERIA ...................................................................................................... 5
VARIANCES FROM THE CRITERIA .......................................................................................... 5
DRAINAGE FACILITY DESIGN ............................................................................................... 6
GENERAL CONCEPT ....................................................................................................... 6
STORMWATER POLLUTION PREVENTION/EROSION CONTROL ................................................... 6
TEMPORARY EROSION CONTROL ..................................................................................... 6
PERMANENT EROSION CONTROL ..................................................................................... 6
CONCLUSIONS .................................................................................................................. 7
REFERENCES ...................................................................................................................... 7
Appendix A – Referenced Information
1. Vicinity Map
2. Drainage and Erosion Control Report for the Trail Head Property
3. Geotechnical Report Soil Boring Log Summary
4. FEMA FIRM Map
5. NRCS Websoil Survey
6. Figure 1: Drainage Plan Existing
7. Figure 2: Drainage Plan Proposed
Appendix B – Hydrologic/Hydraulic Computations
1. Rational Method Calculations
2. Grass Buffer Calculations
Trail Head Park Final Drainage Report
Page 2 of 7
ENGINEER’S STATEMENT:
“I hereby certify that this report (plan) for the Final Drainage Design for the Trail Head Park was
prepared by me (or under my direct supervision) in accordance with the provisions of the City of
Fort Collins Standards for the Responsible Parties thereof. I understand that the City of Fort Collins
does not and shall not assume liability for drainage facilities designed by others.”
______________________________
Kevin A. Tone, P.E.
Registered Professional Engineer
State of Colorado No. 28699
Trail Head Park Final Drainage Report
Page 3 of 7
GENERAL LOCATION AND EXISTING SITE INFORMATION
The Trail Head Park (site) is located in Section 4, Township 7 North, Range 68 West of the 6th
Principal Meridian, in Larimer County, Fort Collins, Colorado. Refer to Appendix A for the site
vicinity map. The site is bordered to the north by Yule Trail Drive and Roaring Creek Drive, to
the west by Wagon Trail Road, and to the east by Greenfields Drive. Developed residential areas
are to the north, south, east and west of the site. The existing site, platted as Tract H and Lot 1-
Block 9 (same owner: City of Fort Collins) of the Trail Head Development, is predominantly park
turf lawn and vegetation. This site was part of the master drainage plan for the Trail Head Property
and is included in the study performed by JR Engineering in 2004. The design requirements and
constraints are outlined in the Drainage and Erosion Control Report dated October 13, 2004 and
included in Appendix A.
The site is approximately 6.26 acres of undeveloped property and has an existing percent
impervious of 12.1%. The existing ground surface is relatively flat, generally sloping to the west
at grades ranging from 0.1% to 3.0%, with an area of steep slope down to the group of trees at the
southeast of the site.
From the geotechnical report dated December 30, 2019 the soil is mainly sandy clay. Groundwater
was encountered at 28 ft to 30 ft below the ground surface. The Summary Logs of Exploratory
Borings from the geotechnical report is attached in Appendix A.
The site is located outside FEMA and City of Fort Collins mapped 100-year and 500-year
floodplains, per FEMA Flood Risk Map Number 08069C0982F, effective date 12/19/2006. The
site is comprised of hydrologic soil group C/D per NRCS soil survey. The FEMA Firm Map and
NRCS Websoil Survey are included in Appendix A.
In general, the proposed redevelopment of the site consists of constructing four new structures,
reconfiguring the striping on Roaring Creek Drive to accommodate parallel parking, connecting
proposed pedestrian pathways to existing perimeter pedestrian pathways in multiple locations,
constructing a new basketball court, constructing new playground equipment and garden areas,
and a bioretention/grass buffer. Grass buffers will be located on the north and west sides of the site
and will tie into the proposed and existing storm system along Wagon Trail Road.
The site development will increase the overall percent impervious by 12% to a total of 24.8%.
However, from the existing drainage report, the site consists of portions of existing sub basins
344.1, 344.2, 345, 352.1 and 352.2. From the existing drainage report, Lot 1-Block 9 was planned
to be a day care building with parking lot (commercial), while Tract H was planned to be the park.
The average proposed imperviousness for the sub basins was calculated to be 33.2%. While the
site generally conforms to the existing drainage report, the majority of stormwater runoff is
conveyed via surface flow either to the west into an existing quadruple curb inlet in Wagon Trail
Road or to the north into Greenfields Drive or Yule Trail Drive and conveyed to an existing curb
inlet at Yule Trail Drive and Roaring Creek Drive, with bypass flows continuing down Roaring
Creek Drive to the quadruple curb inlet in Wagon Trail Road. The inlets are conveyed to the public
storm drain system to the west and eventually to the existing Pond A per the existing drainage
report.
Trail Head Park Final Drainage Report
Page 4 of 7
DRAINAGE BASINS AND HISTORIC RUNOFF
HISTORIC DRAINAGE
The existing site consists of four historical onsite basins H1, H2, H3, and H4. Each of the onsite
basins consists of existing undeveloped landscaped area. In addition, there are five historical offsite
basins OS1, OS2, OS3, OS4 and OS5. See Figure 1 Drainage Plan Existing in Appendix A. Runoff
from Basin H1 drains offsite to the north and east and is collected by the existing inlet on Roaring
Creek Drive. Runoff from Basin H2 travels to the west and is collected by the existing inlet on
Wagon Trail Road. Runoff from Basins H3 and H4 drains to the west and is captured in the inlet
in Wagon Trail Road. Offsite Basin OS1 primarily consists of half of the adjacent roads
Greenfields Drive and Yule Trail Drive. Runoff from Basin OS1 flows west towards the inlet in
Roaring Creek Drive. Offsite Basin OS2 primarily consists of half of the adjacent road Roaring
Creek Drive. Runoff from Basin OS2 flows south and west towards the inlet in Roaring Creek
Drive. Offsite Basins OS3 and OS4 primarily consist of half of the adjacent road Wagon Trail
Road. Runoff from Basins OS3 and OS4 flows towards the inlet in Wagon Trail Road. Offsite
Basin OS5 consists of undeveloped landscape area. Runoff from Basin OS5 flows north and west
onto the site and continues to flow to the inlet on Wagon Trail Road. There is no existing onsite
detention for the site. Stormwater is conveyed via an existing storm sewer system to existing
detention Pond A located southwest of the site.
Per the Drainage and Erosion Control Report prepared by JR Engineering, the existing Pond A
discharges south, under E Vine Drive into an existing swale on the Witham property. Stormwater
flows south towards the Boxelder Creek and ultimately to the Cache La Poudre River.
PROPOSED DRAINAGE
Proposed drainage patterns are to remain generally the same as the current, but will utilize
landscaped areas, inlets, and grass buffers to capture the majority of runoff before discharging into
the public storm system. The grass buffer areas will be utilized for water quality and low impact
development (LID) treatment. Two formal grass buffer areas are proposed in the northern portion
of the site and the southwestern portion of the site. The existing tree area is proposed to not be
disturbed and will have grass around it that will be used as a non-formal grass buffer in the center
of the site. The site will be graded as such to meet the City’s requirements of treating 75% of the
sites modified or added impervious area. Detention will not be required as we are meeting the
planned design outlined in the previous master drainage plan, “Drainage and Erosion Control
Report – Trail Head Property”, prepared by JR Engineering.
The proposed site consists of seven onsite basins A, B, C, D, E, F and G. In addition, there are 11
offsite basins OSA1, OSA2, OSB1, OSC1, OSD1, OSE1, OS1, OS2, OS3, OS4, and OS5. Basin
A consists of concrete walks and a formal grass buffer area. Runoff from Basin A drains southwest
through a proposed formal grass buffer and is captured in the proposed storm system. Basins B
and D consist of concrete and gravel walks as well as landscape areas. Basins C and E consist of
concrete and gravel walks, a portion of roof area and landscape areas. Basins F and G consist of
concrete and gravel walks, a portion of roof area, a portion of playground area and landscape areas.
Runoff from Basins B, C,D, and E drains primarily to the west and flows through the non-formal
grass buffer area prior to entering the proposed storm system. Runoff from Basins F and G drains
primarily to the southwest and flows through the non-formal grass buffer area.
Trail Head Park Final Drainage Report
Page 5 of 7
Offsite Basins OSA1 and OSA2 consist of onsite areas with concrete walks that drain offsite
towards the adjacent roads Greenfield Drive, Yule Trail Drive and Roaring Creek Drive. Offsite
Basins OSB1, OSC1, and OSD1 consist of offsite areas that drain onsite and combine with runoff
from basins B, C and D respectively. Offsite Basin OSE1 consists of onsite area with concrete
walks, gravel walks, a portion of the basketball court and a proposed grass buffer. A portion of the
runoff from Basin OSE1 flows through the existing natural grass buffer area and continues west
offsite. The remainder of the runoff from Basin OSE1 drains west through the proposed formal
grass buffer area and offsite to the inlet in Wagon Trail Road. Runoff from Basin OS1 flows west
towards the inlet in Roaring Creek Drive. Offsite Basin OS2 primarily consists of half of the
adjacent road Roaring Creek Drive. Runoff from Basin OS2 flows south and west towards the inlet
in Wagon Trail Road. Offsite Basins OS3 and OS4 primarily consist of half of the adjacent road
Wagon Trail Road. Runoff from Basins OS3 and OS4 flows towards the inlet in Wagon Trail
Road. Offsite Basin OS5 consists of undeveloped landscape area. Runoff from Basin OS5 flows
north and west onto the site and continues to flow to the inlet on Wagon Trail Road. See Figure 2
Drainage Plan Proposed in Appendix A.
DRAINAGE DESIGN CRITERIA
HYDROLOGIC METHOD AND DESIGN STORM FREQUENCIES
The drainage for the site was designed to meet or exceed the City of Fort Collin’s Standards and
Specifications, including the Stormwater Criterial Manual which incorporates most of the Mile
High Flood District’s (MFHD) Urban Storm Drainage Criteria Manual (USDCM).
The design one hour point rainfall used for the 2 year and 100 year storm events are 0.82 inches
and 2.86 inches respectively.
The Rational Method (Q=CIA) was used to determine the storm runoff (Q) from the areas
contributing to the new storm system, with composite runoff coefficients (C) and contributing
areas (A) given for design points in sub-basins. The runoff coefficients for various land usages
were obtained from Table 6-5, USDCM, Vol. 1. Intensities (I) were determined using the Time-
Intensity-Frequency equations, and a calculated Time of Concentration (tc). Hydraulic Criteria.
See Appendix B for the runoff coefficient calculations.
HYDRAULIC CRITERIA
The proposed drainage facility has been designed to comply with the City of Fort Collins
Stormwater Criteria Manual. The MHFD UD-BMP spreadsheet version 3.07 was used to analyze
the designed grass buffers. Area drains were sized using MHFD’s USDCM Section 3.3.6 and
calculations are included with the rational calculations in Appendix B. Complete drainage plans,
details, dimensions, etc. are included in the grading and drainage plans in the site’s construction
documents.
VARIANCES FROM THE CRITERIA
No variances are requested for this design.
Trail Head Park Final Drainage Report
Page 6 of 7
DRAINAGE FACILITY DESIGN
GENERAL CONCEPT
The site’s private storm drainage system has been designed to convey the 100-year storm event
through a combination of inlets and pipes that connect into the existing sump inlet in Wagon Trail
Road. The site was graded to capture runoff into the storm system and direct it to the existing inlet
located on the west edge of the site. The site was graded to minimize the amount of flow being
directed to the adjacent roads.
The proposed formal and non-formal grass buffers located on the private storm system will treat
storm runoff for a minimum of 75% of the modified or added impervious area on the site for water
quality prior to discharge into the public storm system, satisfying the City of Fort Collins LID
requirements. These features will facilitate sedimentation and filtration while limiting erosion,
providing both treatment and slowed release of the water quality capture volume. The proposed
redevelopment of this site will serve to limit water quality and quantity impacts to natural
drainageways by decreasing the frequency, rate, duration, and volume of runoff.
The site has been designed to minimize directly connected impervious areas by grading the site
such that stormwater runoff sheet flows from paved areas through landscaped areas to formal and
non-formal grass buffers to be treated prior to entering the proposed and existing storm systems.
STORMWATER POLLUTION PREVENTION/EROSION CONTROL
During construction, temporary erosion and sediment control practices will be used to limit soil
erosion and sediment discharge off the site.
TEMPORARY EROSION CONTROL
A temporary erosion control plan is to be implemented for the site during construction. Temporary
erosion control measures include, but are not limited to, slope and swale protection provided using
erosion control wattles/sediment control logs, rock socks, etc. All temporary erosion control
measures are to be removed after they are deemed unnecessary. A general erosion control plan has
been provided in the civil construction documents and attached.
PERMANENT EROSION CONTROL
Chapter 2 of the Urban Drainage and Flood Control District’s Urban Storm Drainage Criteria
Manual Volume 3 (USDCM) provides guidelines for the selection of appropriate permanent
structural BMPs for a site that is to be developed or redeveloped. The Trail Head Park is best
characterized as a “conventional redevelopment” with under 1 acre of impervious area on the
project site. The BMP decision tree for such sites is provided in Figure 2-2 of the USDCM. As
previously stated, the site and surrounding vicinity is comprised of hydrologic soil group Type
C/D soils, per the NRCS soil survey.
The water quality capture volume (WQCV) for this site is accounted for in the regional detention
pond. No detention is required on the site. Runoff will be collected in the private storm system
before connecting to the public storm system.
Trail Head Park Final Drainage Report
Page 7 of 7
CONCLUSIONS
This Final Drainage Report for the Trail Head Park has been prepared to comply with the
stormwater criteria set by the USDFCD and the City of Fort Collins.
The proposed drainage system presented in this report is designed to convey the 100-year peak
stormwater runoff through the site via the proposed and existing storm system. Through
calculations, modeling, and review of the proposed storm drain system, there appears to be
adequate capacity to convey the proposed flows.
It can therefore be concluded that development of the Trail Head Park complies with all of the
stormwater jurisdictional criteria and will not adversely affect the existing streets, storm drain
system and/or detention/water quality facilities.
REFERENCES
1. City of Fort Collins Stormwater Criteria Manual, City of Fort Collins, December 2018.
2. “Drainage and Erosion Control Report Trail Head Property”, JR Engineering, Dated
October 13, 2004.
3. “Geotechnical Investigation Proposed Neighborhood Park Trail Head Subdivision Fort
Collins, Colorado”, CTL Thompson Incorporated, Dated August 30, 2019.
4. “Urban Storm Drainage Criteria Manual”, Mile High Flood District, August 2018 version.
APPENDIX A – REFERENCED INFORMATION
Trail Head Park
3403 Yule Trail Dr
Fort Collins, CO
MAP NOT TO SCALE
(Image from Google Earth)
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This unofficial copy was downloaded on Jan-08-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Jan-08-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
0
5
10
15
20
25
30
35
40
0
5
10
15
20
25
30
35
40
10/12
10/12
9/12
11/12
9/12
16/12
WC=14.4
DD=116
SW=4.1
WC=16.6
DD=109
SW=-0.1
WC=18.0
DD=110
SW=-0.2
WC=19.4
DD=109
SW=-0.1
WC=14.4
DD=116
SW=4.1
WC=16.6
DD=109
SW=-0.1
WC=18.0
DD=110
SW=-0.2
WC=19.4
DD=109
SW=-0.1
TH-1
9/12
17/12
11/12
10/12
WC=14.1
DD=114
SW=0.2
SS=0.150
WC=12.1
DD=116
SW=0.4
USGS The National Map: Orthoimagery. Data refreshed April, 2019.
National Flood Hazard Layer FIRMette
0 250 500 1,000 1,500 2,000 Feet
Ü
105°1'8.92"W
40°36'7.43"N
105°0'31.46"W
40°35'40.11"N
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
HAZARD SPECIAL FLOOD AREAS
Without Zone A, V, Base A99 Flood Elevation (BFE)
With BFE or Depth Zone AE, AO, AH, VE, AR
Regulatory Floodway
0.of 2% 1% Annual annual Chance chance Flood flood with Hazard, average Areas
depth areasdrainage of less less than than one one foot square or with mile
Zone X
Future ChanceAnnual Conditions Flood Hazard 1%
Zone X
Area Levee.to with See Reduced Notes. Flood Risk due
Zone X
Area with Flood Risk due to LeveeZone D
NO SCREEN Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood Hazard Zone D
Channel, Culvert, or Storm Sewer
Levee, Dike, or Floodwall
Cross Sections with 1% Annual Chance
17.5 Water Surface Elevation
Coastal Transect
Coastal Transect Baseline
Profile Baseline
Hydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of Study
Jurisdiction Boundary
Digital Data Available
No Digital Data Available
Unmapped
This digital map flood complies maps if with it is FEMA's not void standards as described for the below. use of
The accuracy basemap standards shown complies with FEMA's basemap
The authoritative flood hazard NFHL information web services is derived provided directly by FEMA. from This the map
was reflectnot exported changes on or 4/amendments 6/2020 at 5:subsequent 49:16 PM and to this does date and
time. becomeor The superseded NFHL and effective by new data information over time. may change
This elementsmap map image do not is appear: void if basemap the one or imagery, more of flood the following zone labels,
legend, FIRM panel scale number, bar, map and creation FIRM effective date, community date. Map identifiers,images for
unmapped regulatoryfor purposes. and unmodernized areas cannot be used
Legend
OTHER FLOOD AREAS HAZARD OF
OTHER AREAS
STRGUECNTUERREASL
FEATURES OTHER
MAP PANELS
8
1:6,000
B 20.2
The point pin selected displayed by the on the user map and is does an approximate not represent
an authoritative property location.
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
1/21/2020
Page 1 of 4
4494030 4494050 4494070 4494090 4494110 4494130 4494150 4494170 4494190
4494030 4494050 4494070 4494090 4494110 4494130 4494150 4494170 4494190
498620 498640 498660 498680 498700 498720 498740 498760 498780 498800 498820 498840 498860 498880
498620 498640 498660 498680 498700 498720 498740 498760 498780 498800 498820 498840 498860 498880
40° 35' 54'' N
105° 0' 58'' W
40° 35' 54'' N
105° 0' 47'' W
40° 35' 49'' N
105° 0' 58'' W
40° 35' 49'' N
105° 0' 47'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,220 if printed on A landscape (11" x 8.5") 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
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
35 Fort Collins loam, 0 to 3
percent slopes
C 1.8 37.1%
73 Nunn clay loam, 0 to 1
percent slopes
C 3.1 62.5%
95 Satanta loam, 1 to 3
percent slopes
C 0.0 0.3%
Totals for Area of Interest 4.9 100.0%
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
1/21/2020
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
1/21/2020
Page 4 of 4
SS SS SS SS
SS SS SS
SS
SS SS
SS
SS SS
SS SS
SS
SS
SS
SS SS SS SS SS SS
SS
SS SS
SS
SS
SS
SW
SW SW
SW SW SW SW SW
SW
SW SW SW SW
E
LV
W A G O N T R A I L R O A D
G R E E N F I E L D S D R I V E
Y U L E T R A I L D R I V E
R O A R I N G
D R I V E
C
E
R
E
K
G
G
G
G G
G
G G
G G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
SS SS SS SS
SS SS SS
SS
SS SS
SS
SS SS
SS SS
SS
SS
SS
SS SS SS SS SS SS
SS
SS SS
SS
SS
SS
SW
SW SW
SW SW SW SW SW
SW
SW SW SW SW
E
LV
G
G
G
G G
G
G G
G G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
APPENDIX B – HYDROLOGIC/HYDRAULIC
COMPUTATIONS
JVA Incorporated Job Name: Trailhead Park I% C2 C5 C10 C100
213 Linden Street, S 200 Job Number: 3197c Streets Paved 100% 0.95 0.00 0.95 1.00
Fort Collins, CO 80524 Date: 4/23/20 Concrete Drives/Walks 90% 0.95 0.00 0.95 1.00
Ph: (970) 225 9099 By: EJK Roof 90% 0.95 0.00 0.95 1.00
Gravel 40% 0.50 0.00 0.50 0.63
Landscaping (B soil) 0% 0.15 0.00 0.15 0.19
Trailhead Park Landscaping (C/D soil) 0% 0.25 0.00 0.25 0.31
Historic Runoff Coefficient & Time of Concentration Calculations Playground 10% 0.11 0.00 0.11 0.14
Location: Fort_Collins Artificial Turf 25% 0.20 0.00 0.20 0.25
Minor Design Storm: 2
Major Design Storm: 100
Soil Type: C/D
Basin Design Data
I (%) = 100% 90% 90% 40% 10% 25% 0% 0% I (%) tc Comp
tc
Final
Basin
Name
Design
Point
Apaved
streets
(sf)
Adrives/co
nc (sf)
Aroof
(sf)
Agravel
(sf)
Aplygnd
(sf)
Aart. turf
(sf)
Alscape (B
soil)
(sf)
Alscape (C/D
soil)
(sf)
ATotal
(sf)
ATotal
(ac)
Imp
(%)
C2 C5 C10 C100
Upper
most
Length
(ft)
Slope
(%)
ti
(min)
Length
(ft)
Slope
(%)
Type of Land Surface K
Velocity
JVA Incorporated Job Name: Trailhead Park I% C2 C5 C10 C100
213 Linden Street, S 200 Job Number: 3197c Streets Paved 100% 0.95 0.00 0.95 1.00
Fort Collins, CO 80524 Date: 4/23/20 Concrete Drives/Walks 90% 0.95 0.00 0.95 1.00
Ph: (970) 225 9099 By: EJK Roof 90% 0.95 0.00 0.95 1.00
Gravel 40% 0.50 0.00 0.50 0.63
Landscaping (B soil) 0% 0.15 0.00 0.15 0.19
Trailhead Park Landscaping (C/D soil) 0% 0.25 0.00 0.25 0.31
Composite Runoff Coefficient Calculations Playground 10% 0.11 0.00 0.11 0.14
Location: Fort_Collins Artificial Turf 25% 0.20 0.00 0.20 0.25
Minor Design Storm: 2
Major Design Storm: 100 CA 100yr = 0.78i + 0.11
Soil Type: C/D CB 100yr = 0.47i + 0.426
CC/D 100yr = 0.41i + 0.484)
Basin Design Data
I (%) = 100% 90% 90% 40% 10% 25% 0% 0% I (%)
Basin Name
Design
Point
Apaved
streets
(sf)
Adrives/c
onc (sf)
Aroof
(sf)
Agravel
(sf)
Aplygnd
(sf)
Aart. turf
(sf)
Alscape (B
soil)
(sf)
Alscape
(C/D soil)
(sf)
ATotal
(sf)
ATotal
(ac)
Imp
(%)
C2 C5 C10 C100
A A 5,700 66,197 71,897 1.65 7.1% 0.31 0.00 0.31 0.37
B B 1,170 3,439 18,877 23,486 0.54 10.3% 0.32 0.00 0.32 0.39
C C 2,446 673 6,212 8,479 17,810 0.41 29.7% 0.46 0.00 0.46 0.54
D D 875 588 4,516 5,979 0.14 17.1% 0.38 0.00 0.38 0.44
E E 1,546 13 2,554 17,888 22,001 0.51 11.0% 0.33 0.00 0.33 0.40
F F 1,436 21 867 1,527 6,256 10,107 0.23 17.9% 0.35 0.00 0.35 0.41
G G 1,367 1,096 3,386 5,000 10,849 0.25 18.5% 0.32 0.00 0.32 0.38
OSA1 OSA1 1,927 11,839 13,766 0.32 12.6% 0.35 0.00 0.35 0.41
OSA2 OSA2 2,631 2,283 4,909 9,823 0.23 26.4% 0.40 0.00 0.40 0.46
OSB1 OSB1 3,056 3,056 0.07 0.0% 0.25 0.00 0.25 0.31
OSC1 OSC1 1,733 1,733 0.04 0.0% 0.25 0.00 0.25 0.31
OSD1 OSD1 757 757 0.02 0.0% 0.25 0.00 0.25 0.31
OSE1 OSE1 8,610 423 1,609 1,404 22,072 34,118 0.78 26.1% 0.44 0.00 0.44 0.50
OS1 OS1 11,810 4,890 4,119 20,819 0.48 77.9% 0.81 0.00 0.81 0.86
OS2 OS2 7,170 4,004 2,189 13,363 0.31 80.6% 0.84 0.00 0.84 0.89
OS3 OS3 2,580 1,659 438 4,677 0.11 87.1% 0.88 0.00 0.88 0.94
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
Trailhead Park
Time of Concentration Calculations
Location: Fort_Collins
Minor Design Storm: 2
Major Design Storm: 100
Soil Type: C/D
Sub-Basin Data tc Comp
tc
Final
Basin
Name
Design
Point
ATotal
(ac)
C5
Upper
most
Length
(ft)
Slope
(%)
ti
(min)
Length
(ft)
Slope (%) Type of Land Surface Cv
Velocity
(fps)
tt
(min)
Time of
Conc
ti + tt = tc
Total
Length
(ft)
tc=(L/180)+
10 (min)
Min
tc
A A 1.65 0.00 215 2.0% 23.5 Short Pasture and lawns 7 0.0 0.0 23.5 215 11.2 11.2
B B 1.24 0.00 120 5.0% 12.9 Short Pasture and lawns 7 0.0 0.0 12.9 120 10.7 10.7
C C 0.41 0.00 80 1.5% 15.8 Short Pasture and lawns 7 0.0 0.0 15.8 80 10.4 10.4
D D 0.14 0.00 75 1.5% 15.3 Short Pasture and lawns 7 0.0 0.0 15.3 75 10.4 10.4
E E 0.51 0.00 250 0.8% 34.4 Short Pasture and lawns 7 0.0 0.0 34.4 250 11.4 11.4
F F 0.23 0.00 135 2.0% 18.6 Short Pasture and lawns 7 0.0 0.0 18.6 135 10.8 10.8
G G 0.25 0.00 140 2.0% 18.9 Short Pasture and lawns 7 0.0 0.0 18.9 140 10.8 10.8
OSA1 OSA1 0.32 0.00 40 10.0% 5.9 Short Pasture and lawns 7 0.0 0.0 5.9 40 10.2 5.9
OSA2 OSA2 0.23 0.00 20 5.0% 5.3 Short Pasture and lawns 7 0.0 0.0 5.3 20 10.1 5.3
OSB1 OSB1 0.07 0.00 30 8.0% 5.5 Short Pasture and lawns 7 0.0 0.0 5.5 30 10.2 5.5
OSC1 OSC1 0.04 0.00 30 8.0% 5.5 Short Pasture and lawns 7 0.0 0.0 5.5 30 10.2 5.5
OSD1 OSD1 0.02 0.00 30 8.0% 5.5 Short Pasture and lawns 7 0.0 0.0 5.5 30 10.2 5.5
OSE1 OSE1 0.78 0.00 200 2.0% 22.6 Short Pasture and lawns 7 0.0 0.0 22.6 200 11.1 11.1
OS1 OS1 0.48 0.00 20 4.0% 5.7 500 0.7%
Paved areas & shallow
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
Trailhead Park Developed Storm Runoff Calculations
Design Storm : 100 Year Point Hour Rainfall (P
1) : 2.86
Basin Name
Design Point
Area (ac)
Runoff Coeff
tc (min)
C*A (ac)
I (in/hr)
Q (cfs)
Total tc
(min)
ΣC*A (ac)
I (in/hr)
Q (cfs)
Inlet Type
Q intercepted
Q carryover
Q bypass
Pipe Size (in)
or equivalent
Pipe Material
Slope (%)
Pipe Flow
(cfs)
Max Pipe
Capacity (cfs)
Length (ft)
Velocity (fps)
tt (min)
Total Time
(min)
Notes
A A 1.65 0.37 11.20 0.61 7.37 4.46 11.20 0.61 7.37 4.46 24" Area Drain 12 in PVC 1.1% 4.5 5.3 370 4.2 1.48 12.68
OSB1 OSB1 0.07 0.31 5.50 0.02 9.63 0.21 5.50 0.02 9.63 0.21
B B 1.24 0.39 10.70 0.49 7.51 3.65 10.70 0.49 7.51 3.65
DS of OSB1 & B 10.70 0.51 7.51 3.81 24" Area Drain 12 in PVC 1.7% 3.8 6.4 130 5.1 0.43 11.13
OSC1 OSC1 0.04 0.31 5.50 0.01 9.63 0.12 5.50 0.01 9.63 0.12
C C 0.03 0.54 10.40 0.02 7.60 0.12 10.40 0.02 7.60 0.12
DS of OSC1 & C 10.40 0.03 7.60 0.22 24" Area Drain
DS of B & C 11.13 0.54 7.39 3.97 12 in PVC 2.0% 4.0 6.9 82 5.5 0.25 11.37
DS of C & A 12.68 1.14 7.02 8.01 15 in PVC 1.1% 8.0 9.5 400 4.8 1.39 14.06
OSD1 OSD1 0.02 0.31 5.50 0.01 9.63 0.05 5.50 0.01 9.63 0.05
D D 0.14 0.44 10.40 0.06 7.60 0.46 10.40 0.06 7.60 0.46
DS of OSD1 & D 10.40 0.07 7.60 0.50 24" Area Drain 12 in PVC 1.5% 0.5 6.1 183 4.8 0.63 11.03
E E 0.51 0.40 11.40 0.20 7.32 1.47 11.40 0.20 7.32 1.47 24" Area Drain
F F 0.23 0.41 10.80 0.10 7.48 0.72 10.80 0.10 7.48 0.72
DS of D,E & F 11.40 0.36 7.32 2.65 12 in PVC 1.5% 2.7 6.1 75 4.8 0.26 11.66
G G 0.25 0.38 10.80 0.09 7.48 0.70 10.80 0.09 7.48 0.70 24" Area Drain
DS of F & G 11.40 0.46 7.32 3.34 12 in PVC 1.9% 3.3 6.9 57 5.4 0.17 11.57
OSA1 OSA1 0.32 0.41 5.90 0.13 9.37 1.21 5.90 0.13 9.37 1.21
OSA2 OSA2 0.23 0.46 5.30 0.10 9.76 1.00 5.30 0.10 9.76 1.00
OSE1 OSE1 0.78 0.50 11.10 0.39 7.39 2.91 11.10 0.39 7.39 2.91
OS1 OS1 0.48 0.86 10.70 0.41 7.51 3.10 10.70 0.41 7.51 3.10
OS2 OS2 0.31 0.89 11.10 0.27 7.39 2.01 11.10 0.27 7.39 2.01
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
Trailhead Park Developed Storm Runoff Calculations
Design Storm : 2 Year Point Hour Rainfall (P
1) : 0.82
Basin Name
Design Point
Area (ac)
Runoff Coeff
tc (min)
C*A (ac)
I (in/hr)
Q (cfs)
Total tc
(min)
ΣC*A (ac)
I (in/hr)
Q (cfs)
Inlet Type
Q intercepted
Q carryover
Q bypass
Pipe Size (in)
or equivalent
Pipe Material
Slope (%)
Pipe Flow
(cfs)
Max Pipe
Capacity (cfs)
Length (ft)
Velocity (fps)
tt (min)
Total Time
(min)
Notes
A A 1.65 0.31 11.20 0.50 2.11 1.07 11.20 0.50 2.11 1.07 24" Area Drain 12 in PVC 1.1% 1.1 5.3 370 4.2 1.48 12.68
OSB1 OSB1 0.07 0.25 5.50 0.02 2.76 0.05 5.50 0.02 2.76 0.05
B B 1.24 0.32 10.70 0.40 2.15 0.86 10.70 0.40 2.15 0.86
DS of OSB1 & B 10.70 0.42 2.15 0.89 24" Area Drain 12 in PVC 1.7% 0.9 6.4 130 5.1 0.43 11.13
OSC1 OSC1 0.04 0.25 5.50 0.01 2.76 0.03 5.50 0.01 2.76 0.03
C C 0.03 0.46 10.40 0.01 2.18 0.03 10.40 0.01 2.18 0.03
DS of OSC1 & C 10.40 0.02 2.18 0.05 24" Area Drain
DS of B & C 11.13 0.44 2.12 0.93 12 in PVC 2.0% 0.9 6.9 82 5.5 0.25 11.37
DS of C & A 12.68 0.94 2.01 1.89 15 in PVC 1.1% 1.9 9.5 400 4.8 1.39 14.06
OSD1 OSD1 0.02 0.25 5.50 0.00 2.76 0.01 5.50 0.00 2.76 0.01
D D 0.14 0.38 10.40 0.05 2.18 0.11 10.40 0.05 2.18 0.11
DS of OSD1 & D 10.40 0.06 2.18 0.12 24" Area Drain 12 in PVC 1.5% 0.1 6.1 183 4.8 0.63 11.03
E E 0.51 0.33 11.40 0.17 2.10 0.35 11.40 0.17 2.10 0.35
F F 0.23 0.35 10.80 0.08 2.15 0.17 10.80 0.08 2.15 0.17 24" Area Drain
DS of D,E & F 11.40 0.30 2.10 0.64 12 in PVC 1.5% 0.6 6.1 75 4.8 0.26 11.66
G G 0.25 0.32 10.80 0.08 2.15 0.17 10.80 0.08 2.15 0.17 24" Area Drain
DS of F & G 11.40 0.38 2.10 0.80 12 in PVC 1.9% 0.8 6.9 57 5.4 0.17 11.57
OSA1 OSA1 0.32 0.35 5.90 0.11 2.69 0.30 5.90 0.11 2.69 0.30
OSA2 OSA2 0.23 0.40 5.30 0.09 2.80 0.26 5.30 0.09 2.80 0.26
OSE1 OSE1 0.78 0.44 11.10 0.35 2.12 0.73 11.10 0.35 2.12 0.73
OS1 OS1 0.48 0.81 10.70 0.39 2.15 0.84 10.70 0.39 2.15 0.84
OS2 OS2 0.31 0.84 11.10 0.26 2.12 0.54 11.10 0.26 2.12 0.54
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
Trailhead Park
LID AREA Calculations per City of Fort Collins
The implementation of LID systems requires one of the following two options:
Acres Notes
Total Site Area = 6.26 Area within the drainage boundary
Total Site Impervious Area = 1.47 Area of impervious surfaces
Added or Modified Impervious Area = 0.69 Area of impervious surfaces - existing impervious surface area
Required Impervious Area to
be treated by LID
= 0.52 75% of added or modified impervious area
Total Site Area to LID = 4.51
Provided Impervious Area to LID = 0.56
3197c-Rational Calculations LID AREA Page 6 of 12
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
FLOW CALCULATIONS - GRATE INLET SUMP CONDITION
(Reference: Urban Drainage and Flood Control District Drainage Criteria Manual, 2001, V.1, Section 3.3.6)
(Note: Spreadsheet assumes orifice condition for fully developed flow.)
INLET TYPE: BASIN:
Orifice Equation: Q = Cd*Ao*(2gH)^0.5 K = Clogging Coefficent value
for multiple inlets
Adjust Ao (open area) due to clogging as follows: N Grate
1 1
Effective Area Opening Ae = (1-C) Ao, where: 2 1.5
C = K * Co / N 3 1.75
N = Number of Inlets 4 1.88
Co = Single Inlet Clogging Factor: 5 1.94
Co(grate) = 0.5 (50% clogging) 6 1.97
7 1.98
8 1.99
Number of inlets: N = 1
Inlet Dimensions and Effective Open Area:
Grate Opening: Ao(g) = 1.6 ft^2
Total Ao(g) = 1.60 ft^2
K = 1.00
C = K*Co/N = 0.50
Ae(g) = (1-C)Ao = 0.80 ft^2
Allowable depth: H = 18.0 in = 1.5 ft
Constants: g = 32.20 ft/s^2
Cd = 0.67
Flow Calculations:
Grate Flow: Q = Cd * Ae(g) * (2g*H)^0.5
Qg= 5.27 CFS
Total Intercepted Flow with 1 inlet(s) and
an allowable depth of 18 inches is 5.3 cfs
Required Flow (Q 2 ) = 1.07 cfs Bypass = 0.0 cfs
Required Flow (Q 100 ) = 4.46 cfs Bypass = 0.0 cfs
24" Area Drain A
3197c-Rational Calculations Grate-Sump(UDFCD) A Page 7 of 12
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
FLOW CALCULATIONS - GRATE INLET SUMP CONDITION
(Reference: Urban Drainage and Flood Control District Drainage Criteria Manual, 2001, V.1, Section 3.3.6)
(Note: Spreadsheet assumes orifice condition for fully developed flow.)
INLET TYPE: BASIN:
Orifice Equation: Q = Cd*Ao*(2gH)^0.5 K = Clogging Coefficent value
for multiple inlets
Adjust Ao (open area) due to clogging as follows: N Grate
1 1
Effective Area Opening Ae = (1-C) Ao, where: 2 1.5
C = K * Co / N 3 1.75
N = Number of Inlets 4 1.88
Co = Single Inlet Clogging Factor: 5 1.94
Co(grate) = 0.5 (50% clogging) 6 1.97
7 1.98
8 1.99
Number of inlets: N = 1
Inlet Dimensions and Effective Open Area:
Grate Opening: Ao(g) = 1.6 ft^2
Total Ao(g) = 1.60 ft^2
K = 1.00
C = K*Co/N = 0.50
Ae(g) = (1-C)Ao = 0.80 ft^2
Allowable depth: H = 12.0 in = 1 ft
Constants: g = 32.20 ft/s^2
Cd = 0.67
Flow Calculations:
Grate Flow: Q = Cd * Ae(g) * (2g*H)^0.5
Qg= 4.30 CFS
Total Intercepted Flow with 1 inlet(s) and
an allowable depth of 12 inches is 4.3 cfs
Required Flow (Q 2 ) = 0.89 cfs Bypass = 0.0 cfs
Required Flow (Q 100 ) = 3.81 cfs Bypass = 0.0 cfs
24" Area Drain DS of OSB1 & B
3197c-Rational Calculations Grate-Sump(UDFCD) B Page 8 of 12
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
FLOW CALCULATIONS - GRATE INLET SUMP CONDITION
(Reference: Urban Drainage and Flood Control District Drainage Criteria Manual, 2001, V.1, Section 3.3.6)
(Note: Spreadsheet assumes orifice condition for fully developed flow.)
INLET TYPE: BASIN:
Orifice Equation: Q = Cd*Ao*(2gH)^0.5 K = Clogging Coefficent value
for multiple inlets
Adjust Ao (open area) due to clogging as follows: N Grate
1 1
Effective Area Opening Ae = (1-C) Ao, where: 2 1.5
C = K * Co / N 3 1.75
N = Number of Inlets 4 1.88
Co = Single Inlet Clogging Factor: 5 1.94
Co(grate) = 0.5 (50% clogging) 6 1.97
7 1.98
8 1.99
Number of inlets: N = 1
Inlet Dimensions and Effective Open Area:
Grate Opening: Ao(g) = 1.6 ft^2
Total Ao(g) = 1.60 ft^2
K = 1.00
C = K*Co/N = 0.50
Ae(g) = (1-C)Ao = 0.80 ft^2
Allowable depth: H = 12.0 in = 1 ft
Constants: g = 32.20 ft/s^2
Cd = 0.67
Flow Calculations:
Grate Flow: Q = Cd * Ae(g) * (2g*H)^0.5
Qg= 4.30 CFS
Total Intercepted Flow with 1 inlet(s) and
an allowable depth of 12 inches is 4.3 cfs
Required Flow (Q 2 ) = 0.05 cfs Bypass = 0.0 cfs
Required Flow (Q 100 ) = 0.22 cfs Bypass = 0.0 cfs
24" Area Drain DS of OSC1 & C
3197c-Rational Calculations Grate-Sump(UDFCD) C Page 9 of 12
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
FLOW CALCULATIONS - GRATE INLET SUMP CONDITION
(Reference: Urban Drainage and Flood Control District Drainage Criteria Manual, 2001, V.1, Section 3.3.6)
(Note: Spreadsheet assumes orifice condition for fully developed flow.)
INLET TYPE: BASIN:
Orifice Equation: Q = Cd*Ao*(2gH)^0.5 K = Clogging Coefficent value
for multiple inlets
Adjust Ao (open area) due to clogging as follows: N Grate
1 1
Effective Area Opening Ae = (1-C) Ao, where: 2 1.5
C = K * Co / N 3 1.75
N = Number of Inlets 4 1.88
Co = Single Inlet Clogging Factor: 5 1.94
Co(grate) = 0.5 (50% clogging) 6 1.97
7 1.98
8 1.99
Number of inlets: N = 1
Inlet Dimensions and Effective Open Area:
Grate Opening: Ao(g) = 1.6 ft^2
Total Ao(g) = 1.60 ft^2
K = 1.00
C = K*Co/N = 0.50
Ae(g) = (1-C)Ao = 0.80 ft^2
Allowable depth: H = 12.0 in = 1 ft
Constants: g = 32.20 ft/s^2
Cd = 0.67
Flow Calculations:
Grate Flow: Q = Cd * Ae(g) * (2g*H)^0.5
Qg= 4.30 CFS
Total Intercepted Flow with 1 inlet(s) and
an allowable depth of 12 inches is 4.3 cfs
Required Flow (Q 2 ) = 0.12 cfs Bypass = 0.0 cfs
Required Flow (Q 100 ) = 0.50 cfs Bypass = 0.0 cfs
24" Area Drain DS of OSD1 & D
3197c-Rational Calculations Grate-Sump(UDFCD) D Page 10 of 12
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
FLOW CALCULATIONS - GRATE INLET SUMP CONDITION
(Reference: Urban Drainage and Flood Control District Drainage Criteria Manual, 2001, V.1, Section 3.3.6)
(Note: Spreadsheet assumes orifice condition for fully developed flow.)
INLET TYPE: BASIN:
Orifice Equation: Q = Cd*Ao*(2gH)^0.5 K = Clogging Coefficent value
for multiple inlets
Adjust Ao (open area) due to clogging as follows: N Grate
1 1
Effective Area Opening Ae = (1-C) Ao, where: 2 1.5
C = K * Co / N 3 1.75
N = Number of Inlets 4 1.88
Co = Single Inlet Clogging Factor: 5 1.94
Co(grate) = 0.5 (50% clogging) 6 1.97
7 1.98
8 1.99
Number of inlets: N = 1
Inlet Dimensions and Effective Open Area:
Grate Opening: Ao(g) = 1.6 ft^2
Total Ao(g) = 1.60 ft^2
K = 1.00
C = K*Co/N = 0.50
Ae(g) = (1-C)Ao = 0.80 ft^2
Allowable depth: H = 12.0 in = 1 ft
Constants: g = 32.20 ft/s^2
Cd = 0.67
Flow Calculations:
Grate Flow: Q = Cd * Ae(g) * (2g*H)^0.5
Qg= 4.30 CFS
Total Intercepted Flow with 1 inlet(s) and
an allowable depth of 12 inches is 4.3 cfs
Required Flow (Q 2 ) = 0.35 cfs Bypass = 0.0 cfs
Required Flow (Q 100 ) = 1.47 cfs Bypass = 0.0 cfs
24" Area Drain E
3197c-Rational Calculations Grate-Sump(UDFCD) E Page 11 of 12
JVA Incorporated Job Name: Trailhead Park
213 Linden Street, S 200 Job Number: 3197c
Fort Collins, CO 80524 Date: 4/23/20
Ph: (970) 225 9099 By: EJK
FLOW CALCULATIONS - GRATE INLET SUMP CONDITION
(Reference: Urban Drainage and Flood Control District Drainage Criteria Manual, 2001, V.1, Section 3.3.6)
(Note: Spreadsheet assumes orifice condition for fully developed flow.)
INLET TYPE: BASIN:
Orifice Equation: Q = Cd*Ao*(2gH)^0.5 K = Clogging Coefficent value
for multiple inlets
Adjust Ao (open area) due to clogging as follows: N Grate
1 1
Effective Area Opening Ae = (1-C) Ao, where: 2 1.5
C = K * Co / N 3 1.75
N = Number of Inlets 4 1.88
Co = Single Inlet Clogging Factor: 5 1.94
Co(grate) = 0.5 (50% clogging) 6 1.97
7 1.98
8 1.99
Number of inlets: N = 1
Inlet Dimensions and Effective Open Area:
Grate Opening: Ao(g) = 1.6 ft^2
Total Ao(g) = 1.60 ft^2
K = 1.00
C = K*Co/N = 0.50
Ae(g) = (1-C)Ao = 0.80 ft^2
Allowable depth: H = 12.0 in = 1 ft
Constants: g = 32.20 ft/s^2
Cd = 0.67
Flow Calculations:
Grate Flow: Q = Cd * Ae(g) * (2g*H)^0.5
Qg= 4.30 CFS
Total Intercepted Flow with 1 inlet(s) and
an allowable depth of 12 inches is 4.3 cfs
Required Flow (Q 2 ) = 0.17 cfs Bypass = 0.0 cfs
Required Flow (Q 100 ) = 0.70 cfs Bypass = 0.0 cfs
24" Area Drain G
3197c-Rational Calculations Grate-Sump(UDFCD) G Page 12 of 12
Sheet 1 of 1
Designer:
Company:
Date:
Project:
Location:
1. Design Discharge
A) 2-Year Peak Flow Rate of the Area Draining to the Grass Buffer Q2
= 1.1 cfs
2. Minimum Width of Grass Buffer WG
= 21 ft
3. Length of Grass Buffer (14' or greater recommended) LG
= 250 ft
4. Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft) SG
= 0.020 ft / ft
5. Flow Characteristics (sheet or concentrated)
A) Does runoff flow into the grass buffer across the
entire width of the buffer?
B) Watershed Flow Length FL
= 50 ft
C) Interface Slope (normal to flow) SI
= 0.020 ft / ft
D) Type of Flow SHEET FLOW
Sheet Flow: FL
* SI
< 1
Concentrated Flow: FL
* SI
> 1
6. Flow Distribution for Concentrated Flows
7 Soil Preparation
(Describe soil amendment)
8 Vegetation (Check the type used or describe "Other")
9. Irrigation
(*Select None if existing buffer area has 80% vegetation
AND will not be disturbed during construction.)
10. Outflow Collection (Check the type used or describe "Other")
Notes:
Drainage Basin A
Till 5 CY of compost per 1000 SF to a depth of 6 inches.
Design Procedure Form: Grass Buffer (GB)
MEC
JVA, Inc.
3197c - Trailhead Park
March 3, 2020
UD-BMP (Version 3.07, March 2018)
Existing Xeric Turf Grass
Irrigated Turf Grass
Other (Explain):
Choose One
Choose One
Grass Swale
Street Gutter
Storm Sewer Inlet
Other (Explain):
None (sheet flow)
Slotted Curbing
Level Spreader
Choose One
Other (Explain):
Sheet 1 of 1
Designer:
Company:
Date:
Project:
Location:
1. Design Discharge
A) 2-Year Peak Flow Rate of the Area Draining to the Grass Buffer Q2
= 0.7 cfs
2. Minimum Width of Grass Buffer WG
= 14 ft
3. Length of Grass Buffer (14' or greater recommended) LG
= 25 ft
4. Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft) SG
= 0.020 ft / ft
5. Flow Characteristics (sheet or concentrated)
A) Does runoff flow into the grass buffer across the
entire width of the buffer?
B) Watershed Flow Length FL
= 50 ft
C) Interface Slope (normal to flow) SI
= 0.020 ft / ft
D) Type of Flow SHEET FLOW
Sheet Flow: FL
* SI
< 1
Concentrated Flow: FL
* SI
> 1
6. Flow Distribution for Concentrated Flows
7 Soil Preparation
(Describe soil amendment)
8 Vegetation (Check the type used or describe "Other")
9. Irrigation
(*Select None if existing buffer area has 80% vegetation
AND will not be disturbed during construction.)
10. Outflow Collection (Check the type used or describe "Other")
Notes:
Design Procedure Form: Grass Buffer (GB)
MEC
JVA, Inc.
3197c - Trailhead Park
April 7, 2020
UD-BMP (Version 3.07, March 2018)
Drainage Basin OSE1
Till 5 CY of compost per 1000 SF to a depth of 6 inches.
Existing Xeric Turf Grass
Irrigated Turf Grass
Other (Explain):
Choose One
Choose One
Grass Swale
Street Gutter
Storm Sewer Inlet
Other (Explain):
None (sheet flow)
Slotted Curbing
Level Spreader
Choose One
Other (Explain):
Choose One
Yes No
Choose One
Permanent
None*
Temporary
3197c-UD-BMP_v3.07 OSE1, GB 4/7/2020, 1:17 PM
Choose One
Yes No
Choose One
Permanent
None*
Temporary
3197c-UD-BMP_v3.07, GB 3/3/2020, 12:56 PM
OS3 OS3 0.11 0.88 7.50 0.09 2.46 0.23 7.50 0.09 2.46 0.23
OS4 OS4 0.08 0.87 7.10 0.07 2.51 0.18 7.10 0.07 2.51 0.18
OS5 OS5 0.11 0.25 6.30 0.03 2.63 0.07 6.30 0.03 2.63 0.07
Direct Runoff Total Runoff Inlets Pipe Pipe/Swale Travel Time
3197c-Rational Calculations Q Minor Page 5 of 12
OS3 OS3 0.11 0.94 7.50 0.10 8.59 0.86 7.50 0.10 8.59 0.86
OS4 OS4 0.08 0.93 7.10 0.08 8.76 0.68 7.10 0.08 8.76 0.68
OS5 OS5 0.11 0.31 6.30 0.03 9.16 0.30 6.30 0.03 9.16 0.30
Direct Runoff Total Runoff Inlets Pipe Pipe/Swale Travel Time
3197c-Rational Calculations Q100 Page 4 of 12
paved swales
20 1.7 5.0 10.7 520 12.9 10.7
OS2 OS2 0.31 0.00 20 4.0% 5.7 500 0.6%
Paved areas & shallow
paved swales
20 1.5 5.4 11.1 520 12.9 11.1
OS3 OS3 0.11 0.00 20 3.0% 6.3 160 1.2%
Paved areas & shallow
paved swales
20 2.2 1.2 7.5 180 11.0 7.5
OS4 OS4 0.08 0.00 20 3.5% 5.9 100 0.5%
Paved areas & shallow
paved swales
20 1.4 1.2 7.1 120 10.7 7.1
OS5 OS5 0.11 0.00 20 3.0% 6.3
Paved areas & shallow
paved swales
20 0.0 0.0 6.3 20 10.1 6.3
Initial Overland Time (ti)
Travel Time (tt)
tt=Length/(Velocity x 60)
tc Urbanized Check
ON
3197c-Rational Calculations Developed Tc Page 3 of 12
OS4 OS4 1865 1394 394 3,653 0.08 85.4% 0.87 0.00 0.87 0.93
OS5 OS5 35 4,561 4,596 0.11 0.3% 0.25 0.00 0.25 0.31
TOTAL SITE 23,425 39,655 1,130 16,400 8,600 0 0 183,280 272,490 6.26 24.8% 0.43 0.00 0.43 0.49
Runoff Coeff's
3197c-Rational Calculations Developed C Page 2 of 12
(fps)
tt
(min)
Time of
Conc
ti + tt = tc
Total
Length
(ft)
tc=(L/180)+
10 (min.)
Min
tc
H1 1 7,350 7,350 0.17 0.0% 0.25 0.00 0.25 0.31 40 0.7% 14.4
Short Pasture and
lawns
7 0.0 0.0 14.4 40 10.2 10.2
H2 2 65,822 65,822 1.51 0.0% 0.25 0.00 0.25 0.31 250 1.2% 30.0
Short Pasture and
lawns
7 0.0 0.0 30.0 250 11.4 11.4
H3 3 7,580 7,580 0.17 0.0% 0.25 0.00 0.25 0.31 80 1.8% 14.8
Short Pasture and
lawns
7 0.0 0.0 14.8 80 10.4 10.4
H4 4 139,077 139,077 3.19 0.0% 0.25 0.00 0.25 0.31 500 0.8% 48.6
Short Pasture and
lawns
7 0.0 0.0 48.6 500 12.8 12.8
OS1 OS1 11,810 4,890 4,119 20,819 0.48 77.9% 0.81 0.00 0.81 0.86 20 4.0% 5.7 500 0.7%
Paved areas & shallow
paved swales
20 1.7 5.0 10.7 520 12.9 10.7
OS2 OS2 7,170 3,505 2,688 13,363 0.31 77.3% 0.81 0.00 0.81 0.86 20 4.0% 5.7 500 0.6%
Paved areas & shallow
paved swales
20 1.5 5.4 11.1 520 12.9 11.1
OS3 OS3 2,580 1,225 872 4,677 0.11 78.7% 0.82 0.00 0.82 0.87 20 3.0% 6.3 160 1.2%
Paved areas & shallow
paved swales
20 2.2 1.2 7.5 180 11.0 7.5
OS4 OS4 1865 1075 713 3,653 0.08 77.5% 0.81 0.00 0.81 0.87 20 3.5% 5.9 100 0.5%
Paved areas & shallow
paved swales
20 1.4 1.2 7.1 120 10.7 7.1
OS5 OS5 10,149 10,149 0.23 0.0% 0.25 0.00 0.25 0.31 30 8.0% 5.5 520 0.8%
Paved areas & shallow
paved swales
20 1.8 4.8 10.4 550 13.1 10.4
TOTAL SITE 23,425 10,695 0 0 0 0 0 238,370 272,490 6.26 12.1% 0.34 0.00 0.34 0.40
Basin
Name
Design
Point
Time of
Conc
(tc)
C2 C5 C10 C100 2 5 10 100 ATotal (sf)
ATotal
(ac)
Q2 Q5 Q10 Q100
H1 1 10.2 0.25 0.00 0.25 0.31 2.19 0.00 3.75 7.66 7,350 0.17 0.09 0.00 0.16 0.40
H2 2 11.4 0.25 0.00 0.25 0.31 2.10 0.00 3.58 7.32 65,822 1.51 0.79 0.00 1.35 3.45
H3 3 10.4 0.25 0.00 0.25 0.31 2.18 0.00 3.72 7.60 7,580 0.17 0.09 0.00 0.16 0.41
H4 4 12.8 0.25 0.00 0.25 0.31 1.99 0.00 3.41 6.97 139,077 3.19 1.59 0.00 2.72 6.95
OS5 OS5 10.4 0.25 0.00 0.25 0.31 2.18 0.00 3.72 7.60 10,149 0.23 0.13 0.00 0.22 0.55
TOTAL SITE 272,490 6.26 2.70 0.00 4.61 11.78
Initial Overland Time (ti)
Travel Time (tt) tt=Length/(Velocity x
60)
tc Urbanized Check
ON
Runoff Coeff's Rainfall Intensities (in/hr) Area Flow Rates (cfs)
Runoff Coeff's
3197c-Rational Calculations Historic Page 1 of 12
G
G
G
E
E
E
E
E
E
E
E E
E
E
E E
E
E
W
W
W
CM
CM
CM
CM
CM
CM
SW SW
SW SW
SW SW
SW SW SW
SW SW
G
G
CM
CM
CM
CM
CM
CM
CM
CM
CM
DRAINAGE PLAN
PROPOSED
FIGURE 2
PROJ. NO.
DRAWN:
CHECKED:
DATE:
REVISIONS :
SCALE:
SHEET NUMBER
SHEET TITLE:
ISSUED FOR:
APPROVED:
...
MAY 2020
BDR SUBMITTAL
TRAIL HEAD PARK
FOR THE MARKING OF UNDERGROUND
BEFORE YOU DIG, GRADE, OR EXCAVATE
CALL 2 BUSINESS DAYS IN ADVANCE
IN METRO
DENVER
1-800-922-1987
CENTER OF COLORADO
CALL UTILITY NOTIFICATION
MEMBER UTILITIES
OR 534-6700
Park Planning
& Development
City of
215 North Mason Street
Fort Collins, Colorado 80521
tel: 970.221.6360
www.fcgov.com/parkplanning/
Park Planning & Development
CITY OF FORT COLLINS
FORT COLLINS, COLORADO
TRAIL HEAD PARK
BASIC DEVELOPMENT REVIEW SUBMITTAL
EJK
ETN
CRH
LID TREATMENT AREAS
LID NAME
LID AREA
(SF)
CONTRIBUTING
IMPERVIOUS
AREA (SF)
% OF TOTAL
SITE ADDED
IMPERVIOUS
AREA*
GRASS BUFFER A 61,500 5,700 18.9
GRASS BUFFER
OSE1 9,600 9,033
30.0
NON-FORMAL
GRASS BUFFER 17,775 9,547
31.7
TOTAL = 80.7
*PERCENTAGE IS BASED ON AN ADDED TOTAL SITE IMPERVIOUS AREA OF 30,090 SF
G
G
G
G
G
G
G
G
G
G
G
G
G
E
E
E
E
E
E
E
E E
E
E
E E
E
E
W
W
W
CM
CM
CM
CM
CM
CM
SW SW
SW SW
SW SW
SW SW SW
SW SW
G
G
CM
CM
CM
CM
CM
CM
CM
CM
CM
DRAINAGE PLAN
EXISTING
FIGURE 1
PROJ. NO.
DRAWN:
CHECKED:
DATE:
REVISIONS :
SCALE:
SHEET NUMBER
SHEET TITLE:
ISSUED FOR:
APPROVED:
...
MAR 2020
BDR SUBMITTAL
TRAIL HEAD PARK
FOR THE MARKING OF UNDERGROUND
BEFORE YOU DIG, GRADE, OR EXCAVATE
CALL 2 BUSINESS DAYS IN ADVANCE
IN METRO
DENVER
1-800-922-1987
CENTER OF COLORADO
CALL UTILITY NOTIFICATION
MEMBER UTILITIES
OR 534-6700
Park Planning
& Development
City of
215 North Mason Street
Fort Collins, Colorado 80521
tel: 970.221.6360
www.fcgov.com/parkplanning/
Park Planning & Development
CITY OF FORT COLLINS
FORT COLLINS, COLORADO
TRAIL HEAD PARK
BASIC DEVELOPMENT REVIEW SUBMITTAL
EJK
ETN
CRH
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 14, Sep 13, 2019
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
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
1/21/2020
Page 2 of 4
WC=14.1
DD=114
SW=0.2
SS=0.150
WC=12.1
DD=116
SW=0.4
TH-2
29/12
30/12
16/12
11/12
9/12
WC=15.2
DD=109
SW=0.5
WC=14.6
DD=114
SW=-0.1
WC=15.2
DD=109
SW=0.5
WC=14.6
DD=114
SW=-0.1
TH-3
27/12
24/12
22/12
17/12
WC=6.1
DD=128
SW=8.0
SS=0.120
WC=8.1
DD=133
SW=7.0
WC=6.1
DD=128
SW=8.0
SS=0.120
WC=8.1
DD=133
SW=7.0
TH-4
34/12
19/12
15/12
17/12
13/12
WC=9.0
DD=115
SW=1.3
SS=0.020
WC=9.9
DD=121
SW=1.0
WC=17.4
DD=110
SW=0.3
WC=15.6
DD=108
SW=-0.3
WC=9.0
DD=115
SW=1.3
SS=0.020
WC=9.9
DD=121
SW=1.0
WC=17.4
DD=110
SW=0.3
WC=15.6
DD=108
SW=-0.3
TH-5
9/12
17/12
16/12
WC=21.5
DD=109
LL=38 PI=21
-200=73
WC=21.5
DD=109
LL=38 PI=21
-200=73
TH-6
13/12
16/12
10/12
WC=17.4
DD=106
LL=39 PI=21
-200=69
WC=17.4
DD=106
LL=39 PI=21
-200=69
TH-7
DEPTH - FEET
DRIVE SAMPLE. THE SYMBOL 10/12 INDICATES 10 BLOWS OF A 140-POUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES.
CLAY, SANDY, MOIST. STIFF TO VERY STIFF, BROWN, REDDISH BROWN (CL)
1.
NOTES:
THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN
THIS REPORT.
SAND, SLIGHTLY CLAYEY TO CLAYEY WITH GRAVEL, VERY MOIST TO WET, MEDIUM
DENSE, REDDISH BROWN (SC, SP)
3.
LEGEND:
DEPTH - FEET
WATER LEVEL MEASURED AT TIME OF DRILLING.
Summary Logs of
Exploratory Borings
THE BORINGS WERE DRILLED ON NOVEMBER 15, 2019 USING 4-INCH DIAMETER
CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG.
FIGURE 2
WC
DD
SW
-200
LL
PI
UC
SS
-
-
-
-
-
-
-
-
INDICATES MOISTURE CONTENT (%).
INDICATES DRY DENSITY (PCF).
INDICATES SWELL WHEN WETTED UNDER OVERBURDEN PRESSURE (%).
INDICATES PASSING NO. 200 SIEVE (%).
INDICATES LIQUID LIMIT.
INDICATES PLASTICITY INDEX.
INDICATES UNCONFINED COMPRESSIVE STRENGTH (PSF).
INDICATES SOLUBLE SULFATE CONTENT (%).
2.
CITY OF FORT COLLINS
TRAIL HEAD NEIGHBORHOOD PARK
CTL | T PROJECT NO. FC09141-125