HomeMy WebLinkAboutHEARTSIDE HILL RESIDENTIAL DEVELOPMENT - FDP230007 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORT
FINAL DRAINAGE REPORT
FOR
Heartside Hill
Prepared by:
Highland Development Services
6355 Fairgrounds Ave, Suite 100
Windsor, Colorado 80550
Phone: 970.674.7550
Prepared for:
CARE Housing, Inc.
1303 W. Swallow Road
Fort Collins, CO 80525
Office: 970.282.7522
May 10, 2023
Job Number 21-1045-00
Highland Development Services, Inc.
6355 Fairgrounds Avenue, Suite 100 | Windsor, CO 80550 | 970.674.7550
May 10, 2023
Mr. Basil Hamdan, P.E.
Fort Collins Utilities – Stormwater Department
700 Wood Street
Fort Collins, CO 80522
RE: Final Drainage Report for Heartside Hill
Fort Collins Stormwater Department,
We are pleased to submit for your review, the Final Drainage Report for the Heartside Hill
affordable residential housing project. This report describes the drainage design in accordance
with the City of Fort Collins Stormwater Criteria Manual.
We appreciate your time and consideration in reviewing this submittal. Please call if you have
any questions.
Sincerely,
Highland Development Services
Jason T. Claeys, P.E., LEED AP
Page i
TABLE OF CONTENTS
Table of Contents ............................................................................................................................. i
Engineer Certification ......................................................................................................................ii
General Description and Location .................................................................................................. 1
Site Description and Location ...................................................................................................... 1
Site Soils ....................................................................................................................................... 1
Storm Drainage Criteria .................................................................................................................. 3
Hydrologic Criteria ....................................................................................................................... 3
Hydraulic Criteria ......................................................................................................................... 3
Drainage Basins ............................................................................................................................... 4
Drainage Facility Design .................................................................................................................. 5
Drainage Conveyance Design ...................................................................................................... 5
Detention/Water Quality Pond Design ....................................................................................... 5
Low Impact Development ............................................................................................................... 6
Stormwater Pollution Prevention ................................................................................................... 8
Conclusions ..................................................................................................................................... 9
References .................................................................................................................................... 10
Appendix ....................................................................................................................................... 11
Appendix A – Site Descriptions, Characteristics, & References .................................................. A
Appendix B – Rational Calculations ............................................................................................. B
Appendix C – Pond Calculations .................................................................................................. C
Appendix D – Low Impact Development Calculations ................................................................ D
Appendix E – Inlet, Pipe, & Swale Capacity Calculations ............................................................ E
Page ii
ENGINEER CERTIFICATION
I hereby certify that this report (plan) for the final drainage design of Heartside Hill was
prepared by me (or under my direct supervision) in accordance with the provisions of the City
of Fort Collins Stormwater Criteria Manual and Construction of Public and Private
Improvements 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.
________________________________________
Jason T. Claeys, PE
Registered Professional Engineer
State of Colorado No. 42122
Page 1
GENERAL DESCRIPTION AND LOCATION
SITE DESCRIPTION AND LOCATION
The project site is situated in the southeast quarter of Section 12, Township 6 North, Range 69
West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, in the State of
Colorado. The property consists of Lots 1 and 2, Block 1 of the Heart of the Rockies Second
Subdivision, dated June 9, 1999. Heartside Hill is located within Lot 2, at the northwest corner
of the intersection of S. Lemay Ave. and E. Trilby Rd. Lot 1 contains the existing Heart of the
Rockies Christian Church. It is bounded by private residential lots to the north and west, E.
Trilby Rd. to the south, and S Lemay Ave to the east.
The existing church facilities are anticipated to remain. The site area is currently undeveloped
and is approximately 8.84 acres. The development would consist of up to 72 CARE Housing for
rent apartment units ([6] 12-unit buildings), 9 Habitat for Humanity (H4H) single-family
detached lots, 2 L’arche group homes, and a planned shared community center to be designed
and constructed at a future date. The project is anticipated to be completed in a single phase.
The project site generally slopes from the southwest to the northeast at approximately 4%
toward an existing pond at the northeast of the property. Storm runoff is currently conveyed
from a grate inlet in the pond to a ditch along the east side of the property and into the existing
storm drain sewer. The existing project site is approximately 0.0% impervious. No wetlands are
located within the area of proposed development.
The project site is not located within the FEMA floodway or floodplain and is within the non-
printed FEMA FIRM panel 08069C1200F, effective 12/19/2006. The site is also not located
within the City of Fort Collins floodplain.
The proposed development includes six multi-family buildings with a clubhouse along with
eleven low-income housing lots. The required parking areas, driveways, sidewalks, and open
space are also included in the development. A rain garden is proposed to provide the
stormwater quality enhancement requirement as a low impact development technique.
The site was previously analyzed within the “Drainage Investigation for Heart of the Rockies
Christian Church,” prepared by Messner Engineering, Inc., dated June 29, 1999.
SITE SOILS
The Heatside Hill project site consists primarily of Renohill clay loam and a small portion of
Longmont clay and are both classified as Type D hydrologic group. According to USDA/Natural
Page 2
Resource Conservation Group, Type D soils a have very slow infiltration rate when thoroughly
wet. These soils 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 also have a very slow rate of water
transmission.
Per the “Preliminary Geotechnical Subsurface Exploration Report, Proposed Residential
Development Lots 1 and 2, Heart of the Rockies Second Subdivision”, prepared by Soilogic, Inc.
dated August 13, 2021:
“The subsurface materials encountered in the completed site borings were quite variable across
the site, but generally consisted of a thin mantle of vegetation and topsoil underlain by
brown/beige/rust lean clay with varying amounts of sand. A portion of the near-surface lean
clay encountered at the location of boring B-2 extending to a depth of about 3 to 4 feet below
ground surface was somewhat mottled in color, appeared to contain bedrock fragments and
was identified as possible existing fill material which may have been placed to develop present
site grade. In general, the lean clay varied from medium stiff to very stiff in terms of consistency,
exhibited variable swell potential (ranging from none to very high) at current moisture and
density conditions and extended to depths between 2½ to 18 feet below present site grade,
where it was underlain by brown/olive/beige/gray/rust interbedded claystone/siltstone/
sandstone bedrock of varying composition. The bedrock varied from weathered to very hard in
terms of hardness, also exhibited variable swell potential (ranging from low to high) at in-situ
moisture and density conditions and extended to the bottom of each boring at depths ranging
from approximately 15 to 30 feet below present site grades. In general, we judge the bedrock
unit underlying the site to possess moderate to high swell potential overall.”
Groundwater was also observed during the subsurface soil exploration:
“Groundwater was measured in borings B-1, B-2, B-3 and B-6 at depths between about 13 and
27 feet below ground surface, but was not encountered in any of the remaining site borings to
the depths explored when checked immediately after completion of drilling. When checked
seven (7) days after drilling, groundwater was measured in all borings with the exception of
boring B-3 at depths between about 5 and 15 feet below ground surface. The ground surface in
the area of boring B-3 had been disturbed, such that subsequent groundwater level
measurements could not be completed.”
There are not any borings within the direct vicinity of the proposed detention pond. The
proposed detention pond bottom is 0.75 ft higher than the existing pond bottom. Currently
there is no exposed ground water or wetland vegetation, so it is assumed adequate separation
from groundwater is achieved.
Page 3
STORM DRAINAGE CRITERIA
This drainage report was prepared to meet or exceed the City of Fort Collins Stormwater
Criteria Manual. The Criteria Manual and amendments to the Mile High Flood District’s (MHFD)
Urban Storm Drainage Criteria Manual (USDCM) Volumes 1, 2 and 3 were referenced as
guidelines for this design.
HYDROLOGIC CRITERIA
The rational method was performed to calculate the peak runoff rates for each basin. Percent
imperviousness and runoff coefficients were calculated for each basin using the surface
characteristics of each basin. The time of concentration was calculated using City of Fort Collins
initial time of concentration and the intensity was calculated using the corresponding storm
rainfall depth and the City of Fort Collins’ Intensity-Duration-Frequency Curve. The City of Fort
Collins area has a 2-yr, 1-hr rainfall depth of 0.82 inches and a 100-yr, 1-hr rainfall depth of 2.86
inches. These depths do account for the 1999 adjusted rainfall depths.
HYDRAULIC CRITERIA
The Heartside Hill storm drainage system will been designed to convey the minor and major
storm events through the combination of private drives, storm sewer pipes and swales. Runoff
flows determined with the rational method will be attenuated through the site. Inlet capacities
will be calculated using MHFD’s spreadsheet UD-Inlet_v4.05.xlsm.
The Autodesk Hydraflow Express program will be used to compute the open channel hydraulics
and check the capacities of the drainage swales throughout the site. Flow velocities within
these swales will be reviewed and where flows are found to be supercritical, the swales will be
lined with turf reinforcement mat.
All swale and pipe outlets will be protected with riprap or suitable erosion protection methods.
Storm sewer pipe outlets will be protected using the requirements set by the USDCM for the
protection downstream of culverts.
All supporting calculations are located in the Appendix.
Page 4
DRAINAGE BASINS
The Heartside Hill developed drainage basins are delineated by areas draining through the site.
The drainage basins are placed to limit the runoff flowing from the site into Brittany Street. The
site is broken into 3 main drainage systems:
Drainage Basin D1:
Drainage Basin D1 has an approximate area of 3.74 acres and is approximately 39.8%
impervious. This basin consists of a portion of the existing church property and building, the
future community center, the H4H single-family lots, and the park and open space. Runoff is
conveyed via swales to a curb cut and is conveyed through Rain Garden D1 to detention Pond
D.
Drainage Basin D2:
Drainage Basin D2 has an approximate area of 4.65 acres and is approximately 37.9%
impervious. This basin consists of six low-income housing lots, private drives, parking areas, and
detention Pond D. Runoff is conveyed to Pond D via swales, culverts and curb & gutter. Sub-
Basins D2a, D2b, D2c, and D2d divide the overall Basin D2 for conveyance element sizing and
capacity confirmation.
Drainage Basin OS1:
Drainage Basin OS1 pertains to the drainage from the existing improvements in Lot 1. This basin
has an approximate area of 2.03 acres and is approximately 65.4% impervious. This basin
consists of half of the existing church building, private drives, parking areas, and open space.
Runoff is conveyed via roadways to a swale and to Rain Garden OS1 and ultimately to detention
Pond D.
Page 5
DRAINAGE FACILITY DESIGN
DRAINAGE CONVEYANCE DESIGN
Storm infrastructure to convey runoff will include swales, inlets, and storm sewer pipes.
Stormwater detention and water quality enhancement are achieved through the use of
detention Pond D and Rain Garden D1.
DETENTION/WATER QUALITY POND DESIGN
An extended detention basin, Detention Pond D, will be utilized as the detention and water
quality facility for Heartside Hill. For the preliminary drainage study, the FAA method was used
to determine the detention volume needed. MHFD is referenced for the standard water quality
capture volume (WQCV) with a 40-hr drain time. Below is a brief summary of the proposed
design for the pond:
Pond D:
Extended detention basin for both Lots 1 and 2 with standard water quality treatment. A 100-yr
orifice plate maximizes volume in the pond and restricts release rate into the existing
stormwater system. The existing 100-yr release rate into the existing stormwater system is 13.2
cfs according to the Drainage Investigation for Heart of the Rockies Christian Church, prepared
by Messner Engineering, Inc (Revised June 29, 1999). This release rate was established prior to
the Fossil Creek Basin Master Drainage Plan update and is assumed to be included in the master
plan. The 100-yr water surface elevation is 4911.03 feet, with a maximum depth in the pond of
3.28 feet. During an event that exceeds the 100-yr storm, or the pond outlet should be
obstructed, overtopping will occur along on the east side of the pond into Lemay Ave.
Pond Summary Table
Pond
100-
yr
Peak
Inflow
(cfs)
100-yr
Peak
Release
(cfs)
WQCV
(ac-ft)
Detention
Volume
(ac-ft)
Combined
Volume
(ac-ft)
Total
Volume
Provided
(ac-ft)
Pond
Bottom
(ft)
WQCV
WSE
(ft)
100-yr
WSE
(ft)
Max
Depth
(ft)
Pond
D 44.16 13.20 0.08 0.82 0.90 1.46 4907.75 4908.86 4911.03 3.28
Page 6
LOW IMPACT DEVELOPMENT
The City of Fort Collins updated the Low Impact Development ordinance in 2016 (Ordinance No.
007, 2016) to require:
· Treat at least 75% of any newly developed or redeveloped impervious area using one or
a combination of LID techniques, or
· Treat at least 50% of any newly developed or redeveloped impervious area using one or
a combination of LID techniques when 25% of private driveable surfaces are permeable.
To satisfy the required implementation of Low Impact Development (LID) techniques, Heartside
Hill utilizes two (2) a bioretention ponds, Rain Garden D1 and Rain Garden OS1. Due to site
constraints and the inability to treat the required amount of newly developed impervious area,
the Rain Garden D1 is designed to treat a portion of the newly developed impervious area able
to be directed to the bioretention pond, and Rain Garden OS1 is designed to treat the existing
church impervious area. The rain gardens are designed to treat the total drainage area being
directed to the rain garden. The result is that with the combination of both rain gardens, an
equivalent of 83% of the total onsite impervious area is treated by a LID feature. The water
quality capture volume provided within the LID features is: Rain Garden D1 is 2,914 cu-ft, and
within Rain Garden OS1 is 1,845 cu-ft. Standard water quality capture volume is 0.08 ac-ft,
treating the remaining area that is directed to Pond D. Both the LID and standard WQCVs
provide an additional 20% volume to account for potential loss of volume due to the
accumulation of sediment.
Below is a description of the 4-step process for selecting structural BMPs:
Mile High Flood District (MHFD) recommends a Four Step Process for receiving water
protection that focuses on reducing runoff volumes, treating the water quality capture volume
(WQCV), stabilizing drainageways and implementing long-term source controls. The Four Step
Process applies to the management of smaller, frequently occurring events.
Step 1: Employ Runoff Reduction Practices
To reduce runoff peaks, volumes, and pollutant loads from urbanizing areas, implement Low
Impact Development (LID) strategies, including Minimizing Directly Connected Impervious
Areas (MDCIA).
Page 7
Captured runoff from strategic areas are routed through bioretention pond/rain gardens. Rain
gardens will slow runoff, promote infiltration, and filter runoff prior to being released into the
adjacent storm drain system.
Step 2: Implement BMPs that Provide a Water Quality Capture Volume with Slow Release
The bioretention pond/rain gardens are designed to provide water quality capture volume per
Urban Drainage’s recommendations and calculations. The captured runoff is designed for a 12-
hr drain time.
Step 3: Stabilize Drainageways
Natural Drainageways are subject to bed and bank erosion due to increases in frequency,
duration, rate and volume of runoff during and following development. Because the site will
drain to an existing storm system, bank stabilization is unnecessary with this project.
Step 4: Implement Site Specific and Other Source Control BMPs
The proposed project will improve upon site specific source controls compared to historic
conditions by providing localized trash enclosures within the development for disposal of solid
waste; a rain garden for water treatment prior to flows entering storm systems; and additional
water quality measures to protect and prolong the design life of BMPS delineated in Step 1.
Below is the Low Impact Development summary and all calculations are attached for reference.
LID Treatment Summary
Total Proposed Impervious Area 155,022
Total Impervious Area LID Treated (sq-ft) 128,370
Total % Impervious Area LID Treated 83%
Water Quality Area Treatment Summary
Description Area
(sq-ft)
Area
(acres) Treatment Ratio
Total Area Treated by LID 251,618 5.78 53.6%
Total Area Treated by EDB 202,366 4.65 43.1%
Total Area Not Treated 15,641 0.36 3.3%
Total Improvement Area 469,625 10.78 100.0%
Page 8
STORMWATER POLLUTION PREVENTION
Erosion and sedimentation will be controlled on-site by use of sediment control logs, inlet
protection, and gravel construction entrances. The measures are designed to limit the overall
sediment yield increase due to construction as required by the City of Fort Collins. During
overlot and final grading the soil will be roughened and furrowed perpendicular to the
prevailing winds.
During the performance of the work required by these specifications or any operations
appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the
contractor shall furnish all labor, equipment, materials, and means required. The Contractor
shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance,
and to prevent dust nuisance that has originated from his operations from damaging crops,
orchards, cultivated fields, and dwellings, or causing nuisance to persons. The Contractor will be
held liable for any damage resulting from dust originating from his operations under these
specifications on right-of-way or elsewhere.
It is unlawful to track or cause to be tracked mud or other debris onto public streets or rights-
of-way. Wherever construction vehicles access routes or intersect paved public roads,
previsions must be made to minimize the transport of sediment by runoff or vehicles tracking
onto the paved surface. Stabilized construction entrances are required with base material
consisting of 6” coarse aggregate. The contractor will be responsible for clearing mud tracked
onto public streets on a daily basis.
All temporary and permanent erosion and sediment control practices must be maintained and
repaired as needed to assure continued performance of their intended function. Maintenance
is the responsibility of the contractor.
All disturbed areas must be seeded and mulched within 30 days of project start. Vegetation
shall not be considered established until a ground cover is achieved which is demonstrated to
be mature enough to control soil erosion to the satisfaction of the City Inspector and to survive
severe weather conditions.
Reference the “Erosion Control Report for Heartside Hill” for more detailed information.
Page 9
CONCLUSIONS
This Final Drainage Report for Heartside Hill has been prepared to comply with the stormwater
criteria set by the City of Fort Collins. The proposed drainage system will be designed to convey
the developed peak 100-yr storm water runoff through the site to the proposed detention
pond, and ultimately to the existing storm system. Drainage conveyance systems is designed to
convey drainage to the proposed roadways and collect onsite drainage and treat it in
accordance with LID requirements before discharging it into the proposed detention pond. This
drainage report anticipates the implementation of best management practices for erosion
control, temporary and permanent, and on-site construction facilities.
It can therefore be concluded that development of Heartside Hill complies with the storm
water jurisdictional criteria and the approved City of Fort Collins Stormwater Criteria Manual
and will not adversely affect the adjacent properties, streets, storm drain system and/or
detention/water quality facilities.
Page 10
REFERENCES
1. Urban Storm Drainage Criteria Manual (Volumes 1, 2, and 3), Mile High Flood Control
District, Updated January 2016.
2. Fort Collins Stormwater Criteria Manual, Fort Collins Utilities, City of Fort Collins,
Colorado, Dated December 2018, Adopted January 2019.
3. “Hydrologic Group Rating for Larimer County Area, Colorado”, USDA-Natural Resources
Conservation Service, National Cooperative Soil Survey. Web Soil Survey URL:
http://websoilsurvey.nrcs.usda.gov. [11/15/2021]
4. “Preliminary Geotechnical Subsurface Exploration Report, Proposed Residential
Development Lots 1 and 2, Heart of the Rockies Second Subdivision”, prepared by
Soilogic, LLC, Dated August 13, 2021.
5. “Drainage Investigation for Heart of the Rockies Christian Church”, prepared by Messner
Engineering, Inc., Dated June 29, 1999.
Page 11
APPENDIX
Appendix A – Site Descriptions, Characteristics, & References
Appendix B – Rational Calculations
Appendix C – Pond Calculations
Appendix D – Low Impact Development Calculations
Appendix E – Inlet, Pipe, & Swale Capacity Calculations
Appendix A
APPENDIX A – SITE DESCRIPTIONS, CHARACTERISTICS, & REFERENCES
SITE
Vicinity Map
Scale: 1" = 1000'
PROJECT DATUM: NAVD88
CITY OF FORT COLLINS BENCHMARK #24-94
ON THE NORTHEAST CORNER OF THE INTERSECTION OF EAST TRILBY ROAD AND PORTNER DRIVE, ON TOP OF THE WEST END
OF A CONCRETE HEADWALL
ELEV= 4960.69
CITY OF FORT COLLINS BENCHMARK #25-94
ON THE NORTHWEST CORNER OF THE INTERSECTION OF EAST TRILBY ROAD AND SOUTH LEMAY AVENUE, ON TOP OF THE
SOUTHEAST EDGE OF THE CONCRETE RING TO AN ELECTRIC MANHOLE
ELEV= 4913.16
PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM. SURROUNDING DEVELOPMENTS HAVE USED
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) FOR THEIR VERTICAL DATUMS.
IF NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) IS REQUIRED FOR ANY PURPOSE,
THE FOLLOWING EQUATIONS SHOULD BE USED:
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = 4960.69 (NAVD88 DATUM) - 3.19'
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = 4913.16 (NAVD88 DATUM) - 3.19'
E TRILBY RDS LEMAY AVEBRIT
T
A
N
Y
S
T
AUTUMN RIDGE DRBRITTANY DRHEARTSIDE HILL
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/21/2021
Page 1 of 444826504482690448273044827704482810448285044828904482650448269044827304482770448281044828504482890494720494760494800494840494880494920494960495000495040495080495120
494720 494760 494800 494840 494880 494920 494960 495000 495040 495080 495120
40° 29' 48'' N 105° 3' 44'' W40° 29' 48'' N105° 3' 27'' W40° 29' 39'' N
105° 3' 44'' W40° 29' 39'' N
105° 3' 27'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:1,880 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
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 16, Sep 2, 2021
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
12/21/2021
Page 2 of 4
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
63 Longmont clay, 0 to 3
percent slopes
D 0.8 6.2%
90 Renohill clay loam, 3 to
9 percent slopes
D 12.8 93.8%
Totals for Area of Interest 13.6 100.0%
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.
Rating Options
Aggregation Method: Dominant Condition
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/21/2021
Page 3 of 4
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
12/21/2021
Page 4 of 4
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250
Feet
Ü
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOOD
HAZARD AREAS
Without Base Flood Elevation (BFE)
Zone A, V, A99
With BFE or DepthZone AE, AO, AH, VE, AR
Regulatory Floodway
0.2% Annual Chance Flood Hazard, Areas
of 1% annual chance flood with average
depth less than one foot or with drainage
areas of less than one square mileZone X
Future Conditions 1% Annual
Chance Flood HazardZone X
Area with Reduced Flood Risk due to
Levee. See Notes.Zone X
Area with Flood Risk due to LeveeZone D
NO SCREEN Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood HazardZone 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 map complies with FEMA's standards for the use of
digital flood maps if it is not void as described below.
The basemap shown complies with FEMA's basemap
accuracy standards
The flood hazard information is derived directly from the
authoritative NFHL web services provided by FEMA. This map
was exported on 12/7/2021 at 10:59 AM and does not
reflect changes or amendments subsequent to this date and
time. The NFHL and effective information may change or
become superseded by new data over time.
This map image is void if the one or more of the following map
elements do not appear: basemap imagery, flood zone labels,
legend, scale bar, map creation date, community identifiers,
FIRM panel number, and FIRM effective date. Map images for
unmapped and unmodernized areas cannot be used for
regulatory purposes.
Legend
OTHER AREAS OF
FLOOD HAZARD
OTHER AREAS
GENERAL
STRUCTURES
OTHER
FEATURES
MAP PANELS
8
B 20.2
The pin displayed on the map is an approximate
point selected by the user and does not represent
an authoritative property location.
1:6,000
105°3'53"W 40°29'57"N
105°3'16"W 40°29'30"N
Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020
FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5)
3.0 Rational Method
3.4 Intensity-Duration-Frequency Curves for Rational Method
Page 8
Table 3.4-1. IDF Table for Rational Method
Duration
(min)
Intensity
2-year
(in/hr)
Intensity
10-year
(in/hr)
Intensity
100-year
(in/hr)
Duration
(min)
Intensity
2-year
(in/hr)
Intensity
10-year
(in/hr)
Intensity
100-year
(in/hr)
5 2.85 4.87 9.95
39 1.09 1.86 3.8
6 2.67 4.56 9.31
40 1.07 1.83 3.74
7 2.52 4.31 8.80
41 1.05 1.80 3.68
8 2.40 4.10 8.38
42 1.04 1.77 3.62
9 2.30 3.93 8.03
43 1.02 1.74 3.56
10 2.21 3.78 7.72
44 1.01 1.72 3.51
11 2.13 3.63 7.42
45 0.99 1.69 3.46
12 2.05 3.50 7.16
46 0.98 1.67 3.41
13 1.98 3.39 6.92
47 0.96 1.64 3.36
14 1.92 3.29 6.71
48 0.95 1.62 3.31
15 1.87 3.19 6.52
49 0.94 1.6 3.27
16 1.81 3.08 6.30
50 0.92 1.58 3.23
17 1.75 2.99 6.10
51 0.91 1.56 3.18
18 1.70 2.90 5.92
52 0.9 1.54 3.14
19 1.65 2.82 5.75
53 0.89 1.52 3.10
20 1.61 2.74 5.60
54 0.88 1.50 3.07
21 1.56 2.67 5.46
55 0.87 1.48 3.03
22 1.53 2.61 5.32
56 0.86 1.47 2.99
23 1.49 2.55 5.20
57 0.85 1.45 2.96
24 1.46 2.49 5.09
58 0.84 1.43 2.92
25 1.43 2.44 4.98
59 0.83 1.42 2.89
26 1.4 2.39 4.87
60 0.82 1.4 2.86
27 1.37 2.34 4.78
65 0.78 1.32 2.71
28 1.34 2.29 4.69
70 0.73 1.25 2.59
29 1.32 2.25 4.60
75 0.70 1.19 2.48
30 1.30 2.21 4.52
80 0.66 1.14 2.38
31 1.27 2.16 4.42
85 0.64 1.09 2.29
32 1.24 2.12 4.33
90 0.61 1.05 2.21
33 1.22 2.08 4.24
95 0.58 1.01 2.13
34 1.19 2.04 4.16
100 0.56 0.97 2.06
35 1.17 2.00 4.08
105 0.54 0.94 2.00
36 1.15 1.96 4.01
110 0.52 0.91 1.94
37 1.16 1.93 3.93
115 0.51 0.88 1.88
38 1.11 1.89 3.87
120 0.49 0.86 1.84
FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5)
3.0 Rational Method
3.4 Intensity-Duration-Frequency Curves for Rational Method
Page 9
Figure 3.4-1. Rainfall IDF Curve – Fort Collins
Appendix B
APPENDIX B – RATIONAL CALCULATIONS
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
TRILBY ROAD
BRI
T
T
A
N
Y
S
T
R
E
E
T
LEMAY AVENUEBRITTANY STREETBRITTANY KNOLLS
BRITTANY KNOLLS
PARAGON POINTBLOCK 1
LOT 1
LOT 2
LOT 3
LOT 4
LOT 1
LOT 2
LOT 3
LOT 4
LOT 5
LOT 6
LOT 7
BLOCK 2
BLOCK 3
LOT 1
TRACT A
(DRAINAGE &
PRIVATE ACCESS
EASEMENT)
BLDG 1
BLDG 2 BLDG 3
BLDG 4
BLDG 5 BLDG 6
DETENTION POND D
100 YR PEAK INFLOW = 44.16 CFS
100 YR RELEASE RATE = 13.2 CFS
100-YR VOLUME = 0.90 AC-FT
100-YR WSE = 4911.03 FT
WQCV (40-HR) = 0.08 AC-FT
WQCV WSE = 4908.85 FT
(STANDARD WQ - AREA NOT
TREATED BY LID)
RAIN GARDEN D1
WQCV (12-HR) = 2,914 CU-FT
RAIN GARDEN OS1
WQCV (12-HR) = 1,845 CU-FT
REVISIONNO.BYDATEHIGHLANDDEVELOPMENT SERVICES6355 FAIRGROUNDS AVENUE, SUITE 100 | WINDSOR, CO 80550PHONE: 970.674.7550 | EMAIL: Info@Highland-DS.com | www.Highland-DS.comPREPARED BY OR UNDER THE
DIRECT SUPERVISION OF:
FOR AND ON BEHALF OF HIGHLAND
DEVELOPMENT SERVICES
OFSHEET
DRAWN BY
CHECKED BY
DATE
SCALE (H)
HDS PROJECT #
SCALE (V)HEARTSIDE HILLDRAINAGE PLAN5/10/23
1" = 40'
N/A
JTC
JTC
21-1045-00
C2.00
9 27
CALL UTILITY NOTIFICATION
CENTER OF COLORADO
CALL 2-BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
before you dig.CallKnow what's below.
R
N
W E
S
0
SCALE: 1" = 40'
80402040
LEGEND
EXISTING MAJOR CONTOUR
EXISTING MINOR CONTOUR
PROPOSED MAJOR CONTOUR
PROPOSED MINOR CONTOUR
BASIN COEFFICIENT (100-YR)
BASIN DESIGNATION
BASIN AREA
DESIGN POINT
DRAINAGE FLOW ARROW
DRAINAGE BASIN BOUNDARY
DRAINAGE BASIN FLOW PATH
NOTES
1.CONTRACTOR TO PROVIDE AND MAINTAIN ALL NECESSARY
EROSION CONTROL MEASURES PRIOR TO AND THROUGHOUT
CONSTRUCTION. PLACE EROSION CONTROL PROTECTION AT
ALL EXISTING INLETS DOWNSTREAM FROM THE CONSTRUCTION
AREA. EROSION CONTROL PROTECTION SHALL REMAIN IN
PLACE UNTIL CONSTRUCTION IS COMPLETE AND ALL DISTURBED
GROUND IS ADEQUATELY VEGETATED WITH OWNER'S APPROVAL
FOR REMOVAL.
2.THE EXTENT OF EROSION CONTROL PROTECTION SHALL BE
OBSERVED AND ADJUSTED AS NEEDED DURING CONSTRUCTION
BASED ON SITE CONDITIONS AND THE PERFORMANCE OF THE
EROSION CONTROL CONTROL MEASURES SHOWN, TO SUPPLY
SUFFICIENT EROSION CONTROL AND MINIMIZE DOWNSTREAM
WATERWAY POLLUTION.
3.LIMIT DISTURBANCE TO AREAS WITHIN EROSION CONTROL
BOUNDARIES. ADJUST EROSION CONTROL BOUNDARIES AS
NECESSARY TO ADEQUATELY COMPLETE PROPOSED WORK. ALL
DISTURBED AREAS SHALL BE PREPARED (SEEDED & MULCHED,
SURFACE ROUGHENING, ETC.) TO MINIMIZE EROSION POTENTIAL
AND SOIL MIGRATION.
4.STORMWATER MANAGEMENT PLAN SHALL BE PREPARED AND
SUBMITTED BY CONTRACTOR PRIOR TO CONSTRUCTION
COMMENCEMENT.
5.SEE LANDSCAPE PLAN FOR REVEGETATION METHODS AND
DETAILS. DURING CONSTRUCTION, ANY SOIL DISTURBED AND
NOT UNDER ACTIVE CONSTRUCTION SHALL BE SEEDED AND
MULCHED PER LCUASS STANDARDS.
6.ANY DISTURBED LAND MUST RECEIVE SURFACE ROUGHENING,
INCLUDING BUT NOT LIMITED TO SLOPED AREAS.
7.AREAS THAT EXPERIENCE EROSION ISSUES FROM STEEP SLOPES
OR WATER EROSION RESULTING IN SEED NOT BEING ABLE TO
ESTABLISH DURING THE FIRST GROWING SEASON SHALL REQUIRE
RESEEDING AND EROSION CONTROL BLANKETS TO STABILIZE THE
SOIL.
Design Engineer:
Design Firm:
Project Number:
Date:
%
Impervious
Runoff
Coefficient C
Return
Period
Frequency
Adjustment
Factor (Cf)
100% 0.95
2-year to
10-year 1.00
90% 0.95 100-year 1.25
90% 0.95
45% 0.55
70% 0.65
0% 0.25
C2 to C10 C100
OS1 88,538 2.03 48,364 3,889 6,687 0 0 29,598 65.4% 0.72 0.89
D1 163,080 3.74 24,710 3,742 5,916 33,798 23,353 71,561 39.8% 0.52 0.65
D2a 48,086 1.10 0 12,931 1,430 0 0 33,725 26.9% 0.46 0.57
D2b 42,280 0.97 231 12,931 1,857 0 0 27,262 32.0% 0.50 0.62
D2a+D2b 90,366 2.07 231 25,861 3,287 0 0 60,987 29.3% 0.48 0.60
D2c 67,394 1.55 44,316 0 4,531 0 0 18,546 71.8% 0.76 0.95
D2d 44,606 1.02 0 0 2,055 0 0 42,551 4.1% 0.28 0.35
D2 202,366 4.65 44,547 25,861 9,874 0 0 122,084 37.9% 0.53 0.66
Total 453,984 10.42 117,621 33,492 22,476 33,798 23,353 223,244 44.0% 0.56 0.70
COMPOSITEApaved
(sq feet)
Aroof
(sq feet)
Awalk
(sq feet)
Alawn
(sq feet)
ASF Lot
(sq feet)
ACC Lot
(sq feet)
Lawns
(Heavy, 2-7% Slope)
Sub-basin
Designation
Atotal
(sq feet)
Atotal
(acres)
Weighted %
Impervious
Single-Family (SF) Lots
Community Center (CC) Lot
Paved
Roof
Walks
Land Use
Heartside Hill
DEVELOPED IMPERVIOUS AREA CALCULATION
DESIGN CRITERIA:
Fort Collins Stormwater Criteria Manual
BASINS:
Highland Development Services
Runoff Coefficients and Frequency Adjustment Factors for City of Fort Collins - Storm Water Criteria Manual
% Impervious values from Table 3.2.2 in the Fort Collins Stormwater Criteria Manual
J.Claeys
20-1045-00
May 10, 2023
21-1045-00 Rational Calcs.xlsx Page 1 of 5 Highland Development Services
Design Engineer:Design Firm:Project Number:Date:EQUATIONS:-Equation 5-3 -Equation 5-4 -Urbanized Check Equation 3.3-5- CoFC Overland FlowCONSTRAINTS:300ft - Overland flow shall not exceed for developed condition500ft - Overland flow shall not exceed for undeveloped conditionFinal tc = minimum of ti + tt and urbanized basin checkrecommended minimum tc = 5 min for urbanized basinsTime of Concentration (2-yr to 10-yr)OS1 OS1 65.4% 0.72 2.03 240 0.0381 7.12 457 0.0128 0.10 0.016 2.27 3.36 10.48 697 13.8710.48D1 D1 39.8% 0.52 3.74 300 0.0282 13.36 468 0.0433 0.10 0.016 4.17 1.87 15.23 768 14.2714.27D2a D2a 26.9% 0.46 1.10 75 0.0760 5.29 371 0.0392 0.14 0.030 2.65 2.33 7.62 446 12.487.62D2b D2b 32.0% 0.50 0.97 18 0.1470 1.96 391 0.0343 0.14 0.030 2.48 2.63 5.00 409 12.275.00D2c D2c 71.8% 0.76 1.55 109 0.0504 3.89 521 0.0389 0.10 0.016 3.96 2.20 6.09 630 13.506.09D2d D2d 4.1% 0.28 1.02 93 0.0492 8.65 233 0.0050 0.14 0.030 0.94 4.11 12.76 326 11.8111.81Total Total 44.0% 0.56 10.42 240 0.0381 10.00 1048 0.0272 0.10 0.030 1.77 9.89 19.89 - -19.89OVERALL LENGTH(ft/ft)tc(min)SLOPE(ft/ft)ti(min)LENGTH(ft)SLOPE(ft/ft)VELOCITY(ft/s)ROUGHNESS COEFFICIENTHYDRAULIC RADIUS(ft)LENGTH(ft)DESIGN CRITERIA:City of Fort Collins Stormwater Criteria ManualOverland Flow Equations for City of Fort Collins Stormwater Criteria ManualSUB-BASIN DATAINITIAL/OVERLAND TIME (ti)TRAVEL TIME (tt)tc=ti+tt(min)Urban CheckFinaltc(min)DESIGN POINTSub-basin%ImperviousC2-10AREA (acres)tt(min)May 10, 2023Heartside HillDEVELOPED TIME OF CONCENTRATIONJ.Claeys21-1045-00Highland Development Servicesticttt+=VLtt60=1.871.1 10180+=LtcV.R2/3S 1/221-1045-00 Rational Calcs.xlsx Page 2 of 5 Highland Development Services
Design Engineer:Design Firm:Project Number:Date:EQUATIONS:-Equation 5-3 -Equation 5-4 -Urbanized Check Equation 3.3-5- CoFC Overland FlowCONSTRAINTS:300ft - Overland flow shall not exceed for developed condition500ft - Overland flow shall not exceed for undeveloped conditionFinal tc = minimum of ti + tt and urbanized basin checkrecommended minimum tc = 5 min for urbanized basinsTime of Concentration (100-yr)OS1 OS1 65.4% 0.89 2.03 240 0.0381 3.80 457 0.0128 0.10 0.016 2.27 3.36 7.16 697 13.877.16D1 D1 39.8% 0.65 3.74 300 0.0282 10.40 468 0.0433 0.10 0.016 4.17 1.87 12.27 768 14.2712.27D2a D2a 26.9% 0.57 1.10 75 0.0760 4.34 371 0.0392 0.14 0.030 2.65 2.33 6.67 446 12.486.67D2b D2b 32.0% 0.62 0.97 18 0.1470 1.56 391 0.0343 0.14 0.030 2.48 2.63 5.00 409 12.275.00D2c D2c 71.8% 0.95 1.55 109 0.0504 1.74 521 0.0389 0.10 0.016 3.96 2.20 5.00 630 13.505.00D2d D2d 4.1% 0.35 1.02 93 0.0492 7.90 233 0.0050 0.14 0.030 0.94 4.11 12.02 326 11.8111.81Total Total 44.0% 0.70 10.42 240 0.0381 7.40 1048 0.0272 0.100.030 1.77 9.89 17.29 - -17.29OVERALL LENGTH(ft/ft)tc(min)SLOPE(ft/ft)ti(min)LENGTH(ft)SLOPE(ft/ft)VELOCITY(ft/s)HYDRAULIC RADIUS(ft)ROUGHNESS COEFFICIENTLENGTH(ft)DESIGN CRITERIA:City of Fort Collins Stormwater Criteria ManualOverland Flow Equations for City of Fort Collins Stormwater Criteria ManualSUB-BASIN DATAINITIAL/OVERLAND TIME (ti)TRAVEL TIME (tt)tc=ti+tt(min)Urban CheckFinaltc(min)DESIGN POINTSub-basin%ImperviousC100AREA (acres)tt(min)May 10, 2023Heartside HillDEVELOPED TIME OF CONCENTRATIONJ.Claeys21-1045-00Highland Development Servicesticttt+=VLtt60=1.871.1 10180+=LtcV.R2/3S 1/221-1045-00 Rational Calcs.xlsx Page 3 of 5 Highland Development Services
Design Engineer:Design Firm:Project Number:Date:EQUATIONS:P1-2yr =0.82inP1-10yr =1.40inP1-100yr =2.86inBASIN SUMMARY:tc(min)Runoff Coeff(C2-10)C(A) (acres)Intensity (in/hr)Q2 (ft3/s)tc(min)Runoff Coeff(C2-10)C(A) (acres)Intensity (in/hr)Q10 (ft3/s)tc(min)Runoff Coeff. (C100)C(A) (acres)Intensity (in/hr)Q100 (ft3/s)OS1 OS1 2.033 65.4% 10.48 0.72 1.46 2.173.1610.48 0.72 1.46 3.715.407.16 0.89 1.82 8.7115.84D1 D1 3.744 39.8% 14.27 0.52 1.94 1.903.6814.27 0.52 1.94 3.256.2812.27 0.65 2.42 7.1017.17D2a D2a 1.104 26.9% 7.62 0.46 0.51 2.451.247.62 0.46 0.51 4.182.126.67 0.57 0.63 8.915.64D2b D2b 0.971 32.0% 5.00 0.50 0.48 2.851.385.00 0.50 0.48 4.872.365.00 0.62 0.60 9.956.02D2c D2c 1.547 71.8% 6.09 0.76 1.17 2.633.086.09 0.76 1.17 4.495.265.00 0.95 1.46 9.9514.57D2d D2d 1.024 4.1% 11.81 0.28 0.29 2.070.6011.81 0.28 0.29 3.531.0211.81 0.35 0.36 7.212.61Total Total 10.422 44.0% 19.89 0.56 5.84 1.619.4319.89 0.56 5.84 2.7616.1017.29 0.70 7.30 6.0544.16Cn = n-yr runoff coefficientIn = n-yr rainfall intensity (in/hr) An = Basin drainage area (ac)I = rainfall intensity (in/hr)P1 = one-hour point rainfall depth (in)tc = time of concentration (min)10-yr Peak Runoff100-yr Peak RunoffHeartside HillDEVELOPED PEAK RUNOFFDESIGN CRITERIA:Design PointSub-basinArea(acres)J.ClaeysHighland Development Services21-1045-00December 21, 20212-yr Peak RunoffCity of Fort Collins Stormwater Criteria Manual%ImperviousQn = n-yr peak discharge (cfs)nnnnAICQ=(0.786651)1)10(5.28ctPI+=21-1045-00 Rational Calcs.xlsx Page 4 of 5 Highland Development Services
Heartside Hill
Attenuated Flows
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA:
EQUATIONS:
-Equation 5-3 -Equation 5-4
-CoFC Overland Flow
CONSTRAINTS:
300 ft - Overland flow shall not exceed for developed condition Final t c = minimum of t i + t t and urbanized basin check
500 ft - Overland flow shall not exceed for undeveloped condition recommended minimum t c = 5 min for urbanized basins
Qn = n -yr peak discharge (cfs)I = rainfall intensity (in/hr)
Cn = n -yr runoff coefficient P1 = one-hour point rainfall depth (in)
In = n -yr rainfall intensity (in/hr) tc = time of concentration (min)
A = drainage area (ac)P1-2yr =0.82 in.
P1-10yr =1.40 in.
P1-100yr =2.86 in.
BASINS:
DP/Manhole D2b
Contributing Basins D2a+D2b
Contributing Area (acres)2.07
C2-10 C100
Runoff Coefficients 0.48 0.60
Overland Flow Time
Length (ft) 75
Slope (%) 7.60
2-yr to
10-yr 100-yr
ti
(min)5.14 4.15
Travel Time
Length (ft) Slope (%)
Hydraulic
Radius (ft)
Roughness
Coefficient Velocity (ft/s)tt (min)
371 3.92%0.10 0.016 3.97 1.56
84 2.74%0.10 0.016 3.32 0.42 pipe conveyance
320 4.03%0.10 0.016 4.03 1.32
Total Time 3.30
Final Time of Concentration - tc (min)
2-yr to
10-yr 100-yr
8.44 7.45
Intensities (in/hr)
2-yr 10-yr 100-yr
2.36 4.03 8.60
Discharge (cfs)
2-yr 10-yr 100-yr
2.34 3.99 10.65
J.Claeys
Highland Development Services
21-1045-00
May 10, 2023
Fort Collins Stormwater Criteria Manual
1.87 1.1
.
V .R2/3 S 1/2
28.5
10 +
. !"#
+ $
$60&
Appendix C
APPENDIX C – POND CALCULATIONS
Design Engineer:
Design Firm:
Project Number:
Date:
Pond
100-yr
Peak
Inflow
(cfs)
100-yr
Peak
Release
(cfs)
WQCV
(ac-ft)
Detention
Volume
(ac-ft)
Combined
Volume
(ac-ft)
Total
Volume
Provided
(ac-ft)
Pond
Bottom
(ft)
WQCV
WSE
(ft)
100-yr
WSE
(ft)
Max
Depth
(ft)
Pond D 44.16 13.20 0.08 0.82 0.90 1.23 4907.75 4908.85 4911.03 3.28
Pond Summary
Heartside Hill
Pond Summary Table
J.Claeys
Highland Development Services
21-1045-00
May 10, 2023
21-1045-00 PondCalcs.xlsx Page 1 of 7 Highland Development Services
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
0.56
1.25
0.70 ft3 acre-ft
10.42 acres 35,584 0.82
13.20 cfs
Time
(min)
100-yr
Intensity
(I , in/hr)
Q100
(cfs)
Accumulative
Runoff Volume
(ft3)
Accumulative
Release
Volume
(ft3)
Detained
Volume
(ft3)
Detained
Volume
(acre-ft)
0 0.00 0.00 0 0 0 0.00
5 9.95 72.58 21,773 3,960 17,813 0.41
10 7.72 56.31 33,786 7,920 25,866 0.59
15 6.52 47.56 42,801 11,880 30,921 0.71
20 5.60 40.85 49,016 15,840 33,176 0.76
25 4.98 36.32 54,486 19,800 34,686 0.80
30 4.52 32.97 59,344 23,760 35,584 0.82
35 4.08 29.76 62,495 27,720 34,775 0.80
40 3.74 27.28 65,471 31,680 33,791 0.78
45 3.46 25.24 68,141 35,640 32,501 0.75
50 3.23 23.56 70,679 39,600 31,079 0.71
55 3.03 22.10 72,933 43,560 29,373 0.67
60 2.86 20.86 75,099 47,520 27,579 0.63
65 2.72 19.84 77,375 51,480 25,895 0.59
70 2.59 18.89 79,344 55,440 23,904 0.55
75 2.48 18.09 81,401 59,400 22,001 0.51
80 2.38 17.36 83,327 63,360 19,967 0.46
85 2.29 16.70 85,187 67,320 17,867 0.41
90 2.21 16.12 87,047 71,280 15,767 0.36
95 2.13 15.54 88,556 75,240 13,316 0.31
100 2.06 15.03 90,154 79,200 10,954 0.25
105 2.00 14.59 91,904 83,160 8,744 0.20
110 1.94 14.15 93,392 87,120 6,272 0.14
115 1.89 13.79 95,121 91,080 4,041 0.09
120 1.84 13.42 96,631 95,040 1,591 0.04
May 10, 2023
Heartside Hill
100-yr Detention Volume - FAA Method
J.Claeys
Highland Development Services
21-1045-00
Adjusted Runoff Coefficient (CC f )
Area (A )
Allowed Release Rate
Fort Collins Amendments to the Urban Drainage and Flood Control District Criteria Manual
City of Fort Collins - Storm Water Criteria Manual
Detention Volume Calculation - Pond D
Runoff Coefficient (C )
Frequency Factor (C f )Required Detention
21-1045-00 PondCalcs.xlsx Page 2 of 7 Highland Development Services
Heartside Hill
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA:
REQUIRED WATER QUALITY CAPTURE VOLUME (WQCV):
Tributary Area, A 4.65 acres Basin D2 (not treated by LID)
Composite. Imperviousness, I 37.9%
WQCV (watershed inches)0.174 inches 40-Hour Drain Time (Fig SQ-2)
Required WQCV 0.081 acre-feet Including 20% for Sedimentation
WATER QUALITY OUTLET SIZING (Per USDCM, Volume 3):
Design Water Quality Depth, DWQ 1.10 ft
Determine K40 K40 = 0.013DWQ
2 + 0.22DWQ - 0.10 0.158
Maximum Area per Row, a a = WQCV / K40 0.514 square inches
Number of Rows, nr 3 rows
Number of Columns, nc (See Table 6a-1 for Max.)1 columns
Choose Hole Diameter 3/4 inches
Use USDCM Volume 3, Figure 5 0.750 inches
Total Area per Row, Ao 0.44 square inches
Total Outlet Area, Aot 1.33 square inches
Does design work?Yes
Minimum Steel Plate Thickness 1/4 inch
(Not Used)
Number of Rows, nr 2 rows
Choose Rectangular Hole Width (w/ 2" Height)0 inches
Use USDCM Volume 3, Figure 5 0.000 inches
Total Outlet Area, Aot 0.00 square inches
Does design work?Yes
Minimum Steel Plate Thickness 1/4 inch
J.Claeys
Highland Development Services
21-1045-00
May 10, 2023
Water Quality Pond and Outlet Sizing - Pond D
Urban Storm Drainage Criteria Manual (USDCM) Volume III, Urban Drainage and Flood Control District, June 2001 (Updated November 2010)
Circular Perforation Sizing
Rectangular Perforation Sizing
12 ∗ ∗ 1.2
21-1045-00 PondCalcs.xlsx Page 3 of 7 Highland Development Services
Heartside Hill
Design Engineer:
Design Firm:
Project Number:
Date:
J.Claeys
Highland Development Services
21-1045-00
May 10, 2023
Water Quality Pond and Outlet Sizing - Pond D
WATER QUALITY TRASH RACK SIZING (Per USDCM, Volume 3)
Required Open Area, At
At=0.5*[77(e-0.124D)]*Aot 46 square inches
Min. Distance between Columns, Sc 3 inches
Width of Trash Rack and Concrete Opening per Column 4 inches
Use USDCM Volume 3, Table 6a-1
Total Width, Wconc 4 inches
Height of Trash Rack Screen, Htr 13 3/16 inches Check - Larger than Required
Type of Screen S.S. #93 VEE Wire (US Filter)
Screen Opening Slot Dimension 0.139" (US Filter)
Support Rod Type (See Table 6a-2)
Spacing of Support Rod (O.C.) 3/4 inches O.C.
Total Screen Thickness (See Table 6a-2) 0.31 inches
Carbon Steel Frame Type (See Table 6a-2)
(Not Used)
Required Open Area, At (including 50% clogging)
At=0.5*[77(e-0.124D)]*Aot 0 square inches
Width of Trash Rack Opening, Wopening 1 inches
Use USDCM Volume 3, Table 6b-1
Width of Concrete Opening, W conc 12 inches
Min Height of Trash Rack Screen, Htr (including 2' 4" below lowest openings)28.00 inches
Type of Screen Kelmp KRP Series Aluminum Bar Gate (or Equal)
Screen Opening Slot Dimension 3/16" Bars on 1-3/16" Centers
Minimum Bearing Bar Size (See Table 6b-2) 1 in x 3/16 in
#156 VEE
3/8in x 1.0in flat bar
Circular Perforation Trash Rack Sizing
Rectangular Perforation Trash Rack Sizing
21-1045-00 PondCalcs.xlsx Page 4 of 7 Highland Development Services
Heartside Hill
Critical Pond Elevations
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
Water Quality Capture Volume (WQCV):
Tributary Area, A 4.65 acres Basin D2 (not treated by LID)
Composite. Imperviousness, I 37.9%
WQCV (watershed inches) 0.174 inches 40-Hour Drain Time (Fig SQ-2)
Required WQCV 0.081 acre-feet Including 20% for Sedimentation
Stage Storage
Volume (pond volume calculated using the prismoidal formula):
CONTOUR (FT)AREA (FT2)AREA (ACRE)VOLUME
(ACRE-FT)DEPTH (FT)CUMULATIVE
VOLUME (ACRE-FT)
4907.75 0 0.000 0.000
0.00 0.000
4908.0 333 0.008 0.001
0.25 0.001
4908.5 4236 0.097 0.022
0.75 0.023
4909.0 10791 0.248 0.083
1.25 0.106
4909.5 15632 0.359 0.151
1.75 0.257
4910.0 17276 0.397 0.189
2.25 0.446
4910.5 18982 0.436 0.208
2.75 0.654
4911.0 21073 0.484 0.230
3.25 0.883
4911.5 23258 0.534 0.254
3.75 1.138
4912.0 0.000 0.089 4.25 1.227
0.08 4908.85 ft
0.90 4911.03 ft
1.32 4911.86 ft
Provided Freeboard (33% Additional Volume) =
Acre-Ft Interpolates to an Elev. of
J.Claeys
Highland Development
21-1045-00
Acre-Ft Interpolates to an Elev. of
Required 100-yr Detention Volume (including WQCV) =
May 10, 2023
Required Water Quality Capture Volume (WQCV) =
Acre-Ft Interpolates to an Elev. of
()
3
2121 DepthAAAAV++=
12 ∗ ∗ 1.2
21-1045-00 PondCalcs.xlsx Page 5 of 7 Highland Development Services
Heartside Hill
Emergency Overflow Spillway Calculations
Design Engineer:
Design Firm:
Project Number:
Date:
Broad-Crested Weir Equation-Trapezoidal Shape
where:Q = Discharge (cfs)
C = Weir Coeffecient
L = Weir Length (ft)
H = Average Weir Head (ft)
H:V =Side Slope
Calculations
Knowns: 4.00
0.75 ft
2.6
4911.80 ft
58.88 cfs
31.87 ft
32 ft
0.00 ft
0.75 ft
4912.55 ft
Side Slopes (H:V)
Desired Spillway Head
Weir Coefficient
Spillway Elevation
J.Claeys
Highland Development Services
21-1045-00
May 10, 2023
Top of Berm Elevation
100-yr Pond Inflow
Calculated Spillway
Use Spillway Length
Total Spillway Depth
Spillway Freeboard
2
5
2
3
H
V
HCCLHQ
+=
21-1045-00 PondCalcs.xlsx - Spillway Page 6 of 7 Highland Development Services
Heartside Hill
Circular Orifice Plate Sizing - Pond D
Design Engineer:
Design Firm:
Project Number:
Date:
Orifice Equation
where:C = Orifice Discharge Coefficient
A o = Orifice Area (ft2)
g = Gravity (32.2 ft/s2)
Dh = Difference in Elevation Head (ft)
D o = Orifice Diameter (in)
Calculations
100-yr Orifice Sizing 100-yr Orifice Rating Table
Knowns: 100-yr Release Rate 13.20 cfs
100-yr WSEL 4911.03 ft 4907.75 0.00 0.000
4908.00 0.00 0.001
Pond Outlet Invert 4907.25 ft 4908.50 4.72 0.023
4909.00 7.23 0.106
Discharge Coefficient 0.65 4909.50 9.08 0.257
4910.00 10.60 0.446
Tailwater Elevation 4908.13 ft 4910.50 11.94 0.654
4911.00 13.13 0.883
Orifice Diameter 16 1/2 in 4911.50 14.23 1.138
4912.00 15.25 1.227
Orifice Area 1.486 ft2
Centroid Elevation 4907.94 ft
Actual Release Rate 13.20 cfs
Pond Volume
(ac-ft)
J.Claeys
Highland Development Services
21-1045-00
May 10, 2023
Elevation
(ft)
Discharge
(cfs)
hgC
QAhgCAQoo D
=D=
2
2
p
o
o
AD576=
21-1045-00 PondCalcs.xlsx Page 7 of 7 Highland Development Services
Appendix D
APPENDIX D – LOW IMPACT DEVELOPMENT CALCULATIONS
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
DDONOTPOLLUTE
RAINSTOWATERWAYS
DUCTILEIRONNYLOPLAST
TRILBY ROAD
BR
I
T
T
A
N
Y
S
T
R
E
E
T
LEMAY AVENUEBRITTANY STREETPOND D
RAIN GARDEN
RAIN GARDEN HIGHLANDDEVELOPMENT SERVICES6355 FAIRGROUNDS AVENUE, SUITE 100 | WINDSOR, CO 80550PHONE: 970.674.7550 | EMAIL: Info@Highland-DS.com | www.Highland-DS.comOFSHEET
DRAWN BY
CHECKED BY
DATE
SCALE (H)
HDS PROJ #
SCALE (V)HEARTSIDE HILLLID & WQ TREATMENT AREAS EXHIBIT5/10/23
1" = 80'
N/A
JTC
JTC
21-1045-00
LID
1 1
AREA CONTRIBUTING TO LID TREATMENT
AREA CONTRIBUTING TO EXTENDED
DETENTION BASIN WATER QUALITY TREATMENT
LEGEND
UNTREATED AREAS
N
W E
S0
SCALE: 1" = 80'
8040
Design Engineer:
Design Firm:
Project Number:
Date:
Sq-Ft Acres
Impervious Area
(sq-ft)
% of Impervious Area
Requiring Treatment
Impervious Area
Requiring
Treatment
105,661 2.43 62,922 0% 0
363,964 8.36 155,022 75% 116,266
443,462 10.78 217,943 - 116,266
LID
Facility
Contributing
Basins
Area Drainage
to LID
(sq-ft)
% Impervious
Impervious
Area Treated
(sq-ft)
WQCV12-hr
(watershed inches)
WQCV12-hr
(cu-ft)
(includes 20% for sedimention)
Treatment
Method
OS1 OS1 88,538 65.4% 58,940 0.20 1,811 Rain Garden
D1 D1 163,080 39.8% 69,430 0.14 2,339 Rain Garden
EDB Pond Contributing
Basins
Drainage Area
(sq-ft)
Drainage Area
(acre)% Impervious WQCV40-hr
(watershed inches)
WQCV40-hr
(ac-ft)
(includes 20% for sedimention)
Pond D D2 202,366 4.65 37.9% 0.17 0.081
155,022
128,370
83%
Area
(sq-ft)
Area
(acres)Treatment Ratio
251,618 5.78 53.6%
202,366 4.65 43.1%
15,641 0.36 3.3%
469,625 10.78 100.0%
Development Area Breakdown
City of Fort Collins - Ordinance No. 007, 2016
- Treat at least 75% of any newly developed or redeveloped impervious area using one or a combination of LID techniques, or
- Treat at least 50% of any newly developed or redeveloped impervious area using one or a combination of LID techniques when 25% of private
driveable surfaces are permeable.
Total Impervious Area LID Treated (sq-ft)
LID Treatment Summary
LID Treatment Areas
Totals
Standard Water Quality Areas
Description
Existing Church Site
Proposed Site
Total Proposed Impervious Area
Total % Impervious Area LID Treated
Low Impact Development Summary
Total Improvement Area
Water Quality Area Treatment Summary
Description
Total Area Treated by LID
Total Area Treated by EDB
Total Area Not Treated
February 21, 2023
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
Heartside Hill
Low Impact Development
J.Claeys
Highland Development Services
21-1045-00
DESIGN CRITERIA
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =39.8 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.398
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.14 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 163,080 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 =0.43 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =1,949 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum)DWQCV =12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin =1298 sq ft
D) Actual Flat Surface Area AActual =2373 sq ft
E) Area at Design Depth (Top Surface Area)ATop =3454 sq ft
F) Rain Garden Total Volume VT=2,914 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?1
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =cu ft
iii) Orifice Diameter, 3/8" Minimum DO = in
Design Procedure Form: Rain Garden (RG)
J.Claeys
Highland Development Services
February 21, 2023
Heartside Hill (Basin D1)
Fort Collins, CO
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
21-1045-00 UD-BMP_v3.07 (Basin D1).xlsm, RG 2/21/2023, 10:55 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
J.Claeys
Highland Development Services
February 21, 2023
Heartside Hill (Basin D1)
Fort Collins, CO
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
21-1045-00 UD-BMP_v3.07 (Basin D1).xlsm, RG 2/21/2023, 10:55 AM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =65.4 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.654
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.20 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 88,538 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 =0.43 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =1,509 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum)DWQCV =12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin =1158 sq ft
D) Actual Flat Surface Area AActual =1453 sq ft
E) Area at Design Depth (Top Surface Area)ATop =2236 sq ft
F) Rain Garden Total Volume VT=1,845 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?1
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =cu ft
iii) Orifice Diameter, 3/8" Minimum DO = in
Design Procedure Form: Rain Garden (RG)
J.Claeys
Highland Development Services
February 21, 2023
Heartside Hill (Basin OS1)
Fort Collins, CO
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
21-1045-00 UD-BMP_v3.07 (Basin OS1).xlsm, RG 2/21/2023, 12:21 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
J.Claeys
Highland Development Services
February 21, 2023
Heartside Hill (Basin OS1)
Fort Collins, CO
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
21-1045-00 UD-BMP_v3.07 (Basin OS1).xlsm, RG 2/21/2023, 12:21 PM
Appendix E
APPENDIX E – INLET, PIPE, & SWALE CAPACITY CALCULATIONS
Heartside Hill
TYPE C AREA INLET SIZING CALCULATION
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
EQUATIONS:
Q i = Grate Capacity w/o Reduction Factor (cfs)
C = Orifice Discharge Coefficient = 0.67
A = Orifice area (ft2) - Open Area of Grate
G = Gravitational Constant (32.2 ft/s2)
H = Allowed Head on Grate, Ponding Depth (ft)
Grate Dimensions and Information:
3 ft
3 ft
0.65 sqft/sqft
50%
5.85 sqft
Allowed Head (ft)
Inlet
Capacity
(Qi, cfs)
Inlet Capacity
w/ Reduction
Factor (Qg, cfs)
0.25 15.73 7.86
0.50 22.24 11.12
1.00 31.45 15.73
1.50 38.52 19.26
2.00 44.48 22.24
INLET SIZING CALCULATIONS
Inlet ID:
Design Flow
Rate
(Q 100 , cfs):
Allowed Head
(H , ft):
Inlet Capacity
(Qg, cfs)
Design
Flow Depth
(H, ft)
Inlet-D2a 5.64 1.5 19.26 0.13
Inlet-D2b 10.65 1.2 17.23 0.46
Outlet-D01 13.20 2.17 23.17 0.70
Outlet-OS1 16.14 0.25 7.86 1.05
Apply Reduction Factor for the Allowable Capacity.
J.Claeys
Highland Development Services
21-1045-00
February 22, 2023
Width (W ):
Assumed Capacity per Head Allowed
Inlet Grate Open Area (A ):
Reduction Factor (F ):
Opening Ratio (R ):
Length (L ):
1
CA 2
Page1
Weir Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, May 9 2023
Inlet-D2c Capacity
Rectangular Weir
Crest = Sharp
Bottom Length (ft) = 15.00
Total Depth (ft) = 0.50
Calculations
Weir Coeff. Cw = 3.33
Compute by: Q vs Depth
No. Increments = 10
Highlighted
Depth (ft) = 0.45
Q (cfs) = 15.08
Area (sqft) = 6.75
Velocity (ft/s) = 2.23
Top Width (ft) = 15.00
0 2 4 6 8 10 12 14 16 18 20
Depth (ft) Depth (ft)Inlet-D2c Capacity
-0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
Length (ft)Weir W.S.
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Feb 15 2023
West Culverts
Circular
Diameter (ft) = 1.25
Invert Elev (ft) = 100.00
Slope (%) = 2.00
N-Value = 0.016
Calculations
Compute by: Q vs Depth
No. Increments = 10
Highlighted
Depth (ft) = 1.13
Q (cfs) = 7.910
Area (sqft) = 1.16
Velocity (ft/s) = 6.80
Wetted Perim (ft) = 3.13
Crit Depth, Yc (ft) = 1.12
Top Width (ft) = 0.75
EGL (ft) = 1.84
0 1 2 3
Elev (ft)Section
99.50
100.00
100.50
101.00
101.50
102.00
Reach (ft)
Exceeds Basin D2a Peak 100-yr
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Feb 20 2023
Inlet-D2b Pipe & East Culverts
Circular
Diameter (ft) = 1.50
Invert Elev (ft) = 100.00
Slope (%) = 1.50
N-Value = 0.016
Calculations
Compute by: Q vs Depth
No. Increments = 10
Highlighted
Depth (ft) = 1.35
Q (cfs) = 11.14
Area (sqft) = 1.68
Velocity (ft/s) = 6.65
Wetted Perim (ft) = 3.75
Crit Depth, Yc (ft) = 1.28
Top Width (ft) = 0.90
EGL (ft) = 2.04
0 1 2 3
Elev (ft)Section
99.50
100.00
100.50
101.00
101.50
102.00
Reach (ft)
Exceeds Peak 100-yr
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Feb 22 2023
Basin D2a & Basin D2b Swale
Triangular
Side Slopes (z:1) = 4.00, 4.00
Total Depth (ft) = 2.50
Invert Elev (ft) = 100.00
Slope (%) = 1.77
N-Value = 0.030
Calculations
Compute by: Q vs Depth
No. Increments = 10
Highlighted
Depth (ft) = 1.50
Q (cfs) = 47.97
Area (sqft) = 9.00
Velocity (ft/s) = 5.33
Wetted Perim (ft) = 12.37
Crit Depth, Yc (ft) = 1.55
Top Width (ft) = 12.00
EGL (ft) = 1.94
0 2 4 6 8 10 12 14 16 18 20 22 24
Elev (ft)Depth (ft)Section
99.50 -0.50
100.00 0.00
100.50 0.50
101.00 1.00
101.50 1.50
102.00 2.00
102.50 2.50
103.00 3.00
Reach (ft)
Minimum Swale Slope