HomeMy WebLinkAboutNORTHFIELD COMMONS - FDP210022 - DOCUMENT MARKUPS - ROUND 2 - DRAINAGE REPORT
FINAL DRAINAGE REPORT
FOR
Northfield Commons
Prepared by:
Highland Development Services
6355 Fairgrounds Ave, Suite 100
Windsor, Colorado 80550
Phone: 970.674.7550
Prepared for:
Mercy Housing
1600 Broadway, Suite 200
Denver, CO 80202
Phone: 303.830.3470
September 8, 2021
Job Number 21-1037-00
City of Fort Collins Approved Plans Approved by: Date: Grading/Stormwater Certification Accepted(Certificat e of Occupancy Released)Accepted by: Date : ☐Escrow washeld forCO and is now released Grading/Stormwater Plan Accepted (Building Permit Released)Accepted by: Date : Utility (Water/Sewer)Plan Approved (Building Permit Released)Approved by: Date : we
Fort Collins Utilities Redlines
Water, Wastewater & S tormwater
Thank you for the opportunity to review the se plans.
I encourage you to contact me to discuss questions &
revisions prior to resubmittal.
dmogen@fcgov.com or 970-305-5989
Reviewed by:
Date :
Dan Mogen
09/28/2021
6355 FAIRGROUNDS AVE, SUITE 100, WINDSOR, COLORADO 80550 | PHONE 970.674.7550
September 8, 2021
Mr. Dan Mogen
Fort Collins Utilities
700 Wood Street
Fort Collins, CO 80522
RE: Final Drainage Report for Northfield Commons
Dear Dan,
We are pleased to submit for your review, the Final Drainage Report for the Northfield
Commons, an amendment to the “Final Drainage Report for Northfield” prepared by Highland
Development Services, dated February 26, 2020. This report describes the drainage design
intent to be in accordance with the criteria in the City of Fort Collins Storm Drainage Manual.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
Sincerely,
Adele Bartel, EI Jason T. Claeys, P.E., LEED AP
Highland Development Services
Page i
TABLE OF CONTENTS
Table of Contents ............................................................................................................................. i
Engineer’s Certification Block ..........................................................................................................ii
General Description and Location .................................................................................................. 1
Site Description and Location ...................................................................................................... 1
Site Soils ....................................................................................................................................... 1
Previous Studies .......................................................................................................................... 2
Storm Drainage Criteria .................................................................................................................. 3
Hydrologic Criteria ....................................................................................................................... 3
Hydraulic Criteria ......................................................................................................................... 3
Drainage Basins ............................................................................................................................... 4
Drainage Facility Design .................................................................................................................. 6
Drainage Conveyance Design ...................................................................................................... 6
Detention/Water Quality Pond Design ....................................................................................... 6
Low Impact Development ............................................................................................................... 8
Stormwater Pollution Prevention ................................................................................................. 10
Conclusions ................................................................................................................................... 11
References .................................................................................................................................... 12
Appendix ....................................................................................................................................... 13
Appendix A – Site Descriptions, Characteristics, & References .................................................. A
Appendix B – SWMM Input/Output ............................................................................................ B
Appendix C – Rational Calculations ............................................................................................. C
Appendix D – Detention Pond Calculations ................................................................................ D
Appendix E – Inlet Calculations ................................................................................................... E
Appendix F – Low Impact Development Calculations ..................................................................F
Page ii
ENGINEER’S CERTIFICATION BLOCK
I hereby attest that this report for the Final Drainage Design for Northfield Commons was
prepared by me (or under my direct supervision) in accordance with the provisions of the Fort
Collins Stormwater Criteria Manual for the owners thereof. I understand that the City of Fort
Collins does not and will 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
Northfield Commons (NFC) is located in the Southeast Quarter of Section 1, Township 7 North,
Range 69 West of the Sixth Principal Meridian, City of Fort Collins, County of Larimer, within the
State of Colorado. NFC is located west of the Alta Vista Subdivision, north of the Rocky
Mountain Raptor Center, south of the proposed Suniga Road, and southeast of the Lake Canal
irrigation ditch. More specifically, NFC is located within the replat of Tracts U & V of Northfield,
with the areas of water quality and detention being provided for these proposed improvements
within Northfield Tract W.
The project site is approximately 6.45 acres and is currently undeveloped agricultural land. The
site appears to be vegetated with grasses harvested for livestock feed. The site generally slopes
from the northwest to the southeast at about 0.5% slope. This area is part of the approved
improvements associated with Northfield and the improvements described within are
considered an amendment to the approved plans and reports. The overall Northfield site is
currently under construction though there are no existing surface improvements currently on
the property.
The property is proposed to be replatted into a multi-family development. NFC will consist of 7
apartment buildings and 4 condominium buildings, along with the associated utility and access
infrastructure.
The NFC improvements are located within the FEMA Zone X, area of 0.2% annual chance of
flood hazard as shown on FEMA FIRM map numbers LOMR 19-08-0715P (effective June 15,
2020). The site is located within the Cache la Poudre River 500-yr floodplain. Critical facilities
are prohibited within the 100-yr and/or 500-yr floodplains. Critical facilities include facilities for
at-risk populations (daycares, schools, nursing homes, etc) and emergency service facilities
(urgent care, hospitals, fire stations, police stations, etc).
SITE SOILS
The NFC site consists of Loveland clay loam and Nunn clay loam and are classified as Type C
hydrologic group. According to USDA/Natural Resource Conservation Group, this soil has a slow
infiltration rate when thoroughly wet. These soils 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.
Page 2
Per the “Preliminary Subsurface Exploration and Groundwater Report – Schlagel Property”,
prepared be Earth Engineering Consultants (EEC), dated August 16, 2017:
Vegetation growth and topsoil was encountered at the surface of each boring. Underlying the
topsoil/vegetation layer was a zone of cohesive subsoils classified lean to fat clay with varying
amounts of sand and clayey sand to approximate depths of 2 to 5-1/2 feet. Underlying the
cohesive subsoils was a granular layer of poorly to well graded sand with silt and gravel
extending to the depths explored at approximately 14 to 21-1/2 feet or to underlying bedrock.
It appears that below the lean to fat clay, there is a granular materials layer that would exhibit
more moderate infiltration rates than the surface materials.
Groundwater was also observed during the subsurface soil exploration:
Groundwater and/or the presence of a piezometric water surface, was generally observed at
depths ranging from approximately 3 to 7 feet below ground surface as indicated on the
enclosed boring logs.
A permanent dewatering system has been installed with the Northfield project and the
groundwater is anticipated to be maintained approximately 9 to 10 feet below the existing
grades.
Supporting figures can be found in Appendix A.
PREVIOUS STUDIES
The Northfield Subdivision originally included the Northfield Commons project site as part of
the drainage design. In the approved Northfield Utility Plans and Final Drainage Report, the NFC
site was broken into sub-basins and analyzed using rational calculations for inlet sizing and EPA
SWMM for pond and conveyance element sizing. These results, along with the LID calculations,
are referenced to provide confirmation that the proposed NFC improvements are within the
previously assumed improvements determined to size the stormwater infrastructure
accordingly. The inlets and storm drains in NFC were sized to accommodate the proposed
improvements. Detention, water quality, and LID calculations were updated as necessary.
Page 3
STORM DRAINAGE CRITERIA
This report was prepared to meet or exceed the City of Fort Collins storm water criteria. The
City of Fort Collin’s Stormwater Criteria Manual was 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.
HYDRAULIC CRITERIA
The NFC storm drainage system has been analyzed to verify conformance with the drainage
system design of Northfield. The NFC system was designed to convey the minor and major
storm events through the combination of private drives, inlets, storm sewer pipes, and pans.
The NFC peak basin runoff flows from the rational calculations were used to size area inlets and
confirm private drive capacities. The EPA SWMM model was used to confirm the proposed
improvements are within the original assumptions of the Northfield Final Drainage Report.
The Northfield drainage design utilized EPA SWMM to model the captured flows and size
conveyance elements and detention ponds. It is assumed that the inlets are free of clogging
debris and capturing the maximum amount of runoff. The program accounts for head losses
within manholes and bends and head losses associated with pipe friction. The SWMM model of
the area encompassed in NFC, Basin D, has been updated for the final report.
All pipe outlets are protected with buried riprap or suitable erosion protection methods. Storm
sewer pipe outlets are protected using the requirements set by the USDCM for the protection
downstream of culverts.
All supporting calculations for runoff rates and inlets are located in the Appendix.
Page 4
DRAINAGE BASINS
The Northfield Commons (NFC) project site is located within Northfield Drainage System D.
Drainage System D outfalls into the existing Northeast College Corridor Outfall (NECCO) storm
system. The descriptions within are an amendment to Northfield’s Drainage System D and
described below:
Drainage System D:
Drainage System D consists of 9.18 acres of improvements within the area south of Suniga
Road. Runoff from basins in the D system drain to an extended detention basin, Pond D.
Sub-basin D1 consists of 3.15 acres of apartment buildings, private drives, and open space.
Runoff is conveyed via roof downspouts, roadways, and concrete pans, and captured by a
Penta Type 13 and a Type C inlet, ultimately discharged to detention Pond D and treated for
standard water quality. The Type C inlet is primarily utilized as a junction for a bend in the
pipe and captures a minimal amount of runoff.
Sub-basins D2 thru D3 consist of 0.15 acres of public roadway. These basins include
portions of Steeley Drive. Runoff from these basins is conveyed along roadways and
captured by two on-grade 5’ Type R curb inlets, ultimately discharging to detention Pond D
and treated for standard water quality.
Sub-basin D4 consists of 0.24 acres of open space and concrete sidewalk. Runoff is
conveyed via sheet flow to a Type C inlet and ultimately discharged to detention Pond D
and treated for standard water quality.
Sub-basins D5 consists of 0.81 acres of apartment buildings, condominiums, and open
space. Runoff is conveyed via roof downspouts, concrete pans and storm pipes and
captured by a 12” FES and five 12” grated dome area inlets ultimately discharging to LID
facility, Rain Garden D1.
Sub-basins D6 consists of 0.16 acres of condominiums and open space. Runoff is conveyed
via roof downspouts and storm pipes and captured by six 12” grated dome area inlets
ultimately discharging to LID facility, Rain Garden D1.
Sub-basins D7 consists of 1.91 acres of condominiums, private drives and open space.
Runoff is conveyed via roof downspouts, concrete pans and storm pipes and captured by an
18” FES that ultimately discharges to LID facility, Rain Garden D1.
Sub-basins D8 consists of 0.28 acres of open space encompassing LID facility, Rain Garden
D1. All runoff in this basin is treated by Rain Garden D1.
Page 5
Sub-basin D9 consists of 2.50 acres of open space encompassing detention Pond D. An
outlet structure in Pond D has been designed as part of the Northfield subdivision to limit
discharge into the NECCO storm system as well as treat for standard water quality
enhancement. The proposed improvements do not impact the approved outlet structure
design and detail, therefore no modifications to the structure or design are required.
No modifications to
pond? I'm
confused by what's
included in the
appendix.
HDS RESPONSE: WORDING
HAS BEEN UPDATED FOR
CLARIFICATION
Page 6
DRAINAGE FACILITY DESIGN
DRAINAGE CONVEYANCE DESIGN
Storm infrastructure to convey runoff includes concrete trickle pans, inlets, storm sewer and
culverts. Stormwater detention and water quality enhancement are achieved through the use
of Northfield Pond D and Northfield Rain Garden D1. Storm inlets, storm sewers and the
roadway culverts have been appropriately sized to convey the minor and major storms.
DETENTION/WATER QUALITY POND DESIGN
Below is an excerpt of the detention and water quality design from the “Final Drainage Report
for Northfield” prepared by Highland Development Services as it pertains to the amended
Northfield Commons development:
EPA SWMM 5.0 has been utilized for the final drainage design. UDFCD is referenced for the
standard water quality capture volume (WQCV) with a 40-hr drain time and the LID rain
gardens and infiltration galleries WQCV with a 12-hr drain time. Below is a brief summary of
the proposed design for each pond:
Pond D:
Extended detention basin for all area south of Suniga Road, with LID rain garden and
standard water quality treatment via the outlet structure located at the north center of the
pond. A 4-3/4” 100-yr orifice plate maximizes volume in the pond and restricts release rate
into the NECCO system. The rain garden includes a concrete forebay sized for 1% of the
surface area for WQCV with a rock embankment to dissipate flows before entering the
media material. Large storm events in excess of the rain garden capacity will spill over a
turf mat reinforced berm and down into Pond D. The 100-yr water surface elevation is
4949.54 feet, with a maximum depth in the pond of 3.92 feet, with another 1.46 feet of
additional volume available. Should the pond outlet become clogged, overtopping will occur
along the east side near design point D15, spilling over the sidewalk across a length of 120
feet at a depth of 0.32 feet (spill elevation = 4951.75), into Lemay Ave public ROW.
As stated, the ultimate outfall for the Northfield site is the existing NECCO storm drain
system. A portion of the area south of Suniga Road (delineated as sub-basins D13-D15) is
allowed to release at a rate equal to current undeveloped/historic rates with the remaining
area (delineated as sub-basins D1-D12) restricted to the 0.2 cfs/acre rate.
Page 7
The comparison of the approved NF Pond D design and the proposed NFC changes are shown
below:
The NFC Peak Runoff is only a 0.3% increase to the approved design while the proposed 100-yr
Detention volume and 100-yr water surface elevation are slightly lower than the approved. The
NFC Spill Depth is 0.02 ft higher than the approved design due to an additional 8 cf s runoff from
Alta Vista Main Street directed toward Pond D. These differences are negligible and will not
require any changes to the approved Pond D structure or design.
I'd like to reach out
to Dan Evans on
this. Has he
reviewed the
model?
HDS RESPONSE: PER CITY
DIRECTION, THE 8 CFS
FLOW WAS NOT MODELED.
THE SPILLWAY WAS
CONFIRMED TO HANDLE
THE EXTRA FLOWS.
Page 8
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,
Northfield Commons utilizes bioretention pond/Rain Garden D1 that was previously designed
as part of the Northfield subdivision.
Impervious calculations for the tributary areas to the rain garden and standard water quality
facility have been updated for the amended site layout. LID treatment requirements for the
entire Northfield subdivision are still exceeded, achieving approximately 104% of the required
impervious area treatment in the rain gardens and infiltration galleries. The water quality
capture volume needed within the rain garden (LID) is 1,995 cu-ft and the pond (standard
WQCV) is 0.090 ac-ft. Both are less than the Northfield design for the rain garden and pond
which are 2,459 cu-ft and 0.092 ac-ft respectively, and therefore will not require redesign.
Below is a description of the 4-step process for selecting structural BMPs:
Urban Drainage and Flood Control District (UDFCD) 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).
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.
Do these numbers
match those on the
RG calc sheet
included in the
appendix?
HDS RESPONSE:
REPORT HAS
BEEN UPDATED
Page 9
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. Riprap
and turf reinforcement mats are utilized throughout for onsite permanent stabilization.
Step 4: Implement Site Specific and Other Source Control BMPs
The proposed project amendment will improve upon site specific source controls compared to
historic conditions by providing localized trash enclosures within the development for disposal
of solid waste; Snouts, and rain gardens 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. are snouts being used?
Are these the snouts on
Suniga - is runoff from this
site conveyed there?
Maybe this is just an
excerpt from Northfield
DR?
I like the trash enclosures and treatment;
they're definitely an improvement for the
developing site, but I don't know that
improving controls compared to historic
conditions where there is no real "source" is
an appropriate comparison for a greenfield
site.
HDS RESPONSE: WORDING
HAS BEEN UPDATED FOR
CLARIFICATION
HDS RESPONSE: OOPS,
THERE ARE NO SNOUTS
BEING USED AND THERE IS
NO RUNOFF CONVEYED TO
SUNIGA. WORDING HAS
BEEN CORRECTED.
Page 10
STORMWATER POLLUTION PREVENTION
Erosion and sedimentation will be controlled on-site by use of sediment control logs, silt
fencing, inlet protection, gravel construction entrances, temporary sediment basins, seeding,
mulch, and turf. 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 naissance 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 city 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 city
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. Silt fence and
sediment control logs will require periodic replacement. 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 condition.
Page 11
CONCLUSIONS
This Final Drainage Report for Northfield Commons has been prepared to comply with the
stormwater criteria set by the City of Fort Collins. The proposed drainage system presented in
this report adheres to the overall Northfield subdivision design. The system conveys the
developed peak storm water runoff through the site to the existing storm drain system and to
the development’s LID features, detention and water quality facilities. The peak flows for the
amended design are slightly less than the original design. 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 Northfield Commons complies with the
storm water jurisdictional criteria and will not adversely affect the adjacent properties, streets,
storm drain system and/or detention/water quality facilities. Controlling the developed runoff
from these improvements will improve the situations currently existing on the site.
Page 12
REFERENCES
1. Urban Storm Drainage Criteria Manual (Volumes 1, 2, and 3), Urban Drainage and Flood
Control District, June 2001, Revised 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. [12/06/2017]
4. “Preliminary Subsurface Exploration and Groundwater Report – Schlagel Property”,
prepared by Earth Engineering Consultants, LLC, Dated August 16, 2017
5. “Flood Insurance Rate Map, Larimer County, Colorado – LOMR 19-08-0751P”, Federal
Emergency Management Agency, Map Revised June 15, 2020.
6. “Final Drainage Report for Northfield”, prepared by Highland Development Services,
Dated February 26, 2020.
Page 13
APPENDIX
Appendix A – Site Descriptions, Characteristics, & References
Appendix B – SWMM Input/Output
Appendix C – Rational Calculations
Appendix D – Detention Pond Calculations
Appendix E – Inlet Calculations
Appendix F – Low Impact Development Calculations
Appendix A
APPENDIX A – SITE DESCRIPTIONS, CHARACTERISTICS, & REFERENCES
SITE
Vicinity Map
Scale: 1" = 1000'
PROJECT DATUM: NAVD88
CITY OF FORT COLLINS BENCHMARK #43-97
ON THE SOUTH END OF THE WEST HEADWALL OF THE LAKE CANAL BRIDGE AT NORTH LEMAY AVENUE, 200 FEET SOUTH OF
THE INTERSECTION OF LEMAY AVENUE AND CONIFER STREET
ELEV= 4960.11
CITY OF FORT COLLINS BENCHMARK #12-07
SOUTH SIDE OF VINE DRIVE ON THE SOUTH HEADWALL OF THE BRIDGE OVER DRY CREEK BASIN 0.4 MILES EAST OF NORTH
LEMAY AVENUE
ELEV= 4947.86
BASIS OF BEARINGS:
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) = 4960.11 (NAVD88 DATUM) - 3.17'
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = 4947.86 (NAVD88 DATUM) - 3.18'
N
W E
S
NORTHFIELD COMMONS
Hydrologic Soil Group—Larimer County Area, Colorado
(NorthField)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/6/2017
Page 1 of 444941304494220449431044944004494490449458044946704494130449422044943104494400449449044945804494670494350494440494530494620494710494800494890494980495070495160
494350 494440 494530 494620 494710 494800 494890 494980 495070 495160
40° 36' 11'' N 105° 4' 2'' W40° 36' 11'' N105° 3' 23'' W40° 35' 52'' N
105° 4' 2'' W40° 35' 52'' N
105° 3' 23'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,140 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 12, Oct 10, 2017
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 20, 2015—Oct
15, 2016
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
(NorthField)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/6/2017
Page 2 of 4
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
64 Loveland clay loam, 0 to
1 percent slopes
C 11.9 20.9%
73 Nunn clay loam, 0 to 1
percent slopes
C 16.6 29.2%
76 Nunn clay loam, wet, 1
to 3 percent slopes
C 28.3 49.9%
Totals for Area of Interest 56.7 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Hydrologic Soil Group—Larimer County Area, Colorado NorthField
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/6/2017
Page 3 of 4
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Larimer County Area, Colorado NorthField
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/6/2017
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 4/23/2021 at 10:39 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°4'9"W 40°36'2"N
105°3'32"W 40°35'35"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
Figure 2. Depth to groundwater over time at Northfield monitoring points (in feet).
Date MW-1 MW-2 PZ-1 PZ-2 PZ-3 PZ-4 PZ-5 PZ-6 PZ-7
7/27/2017 3.8 5.3 4.7 4.6 5.1 5.0 6.0 6.8 7.2
9/19/2017 4.0 5.7 5.2 4.7 5.8 5.3 7.0 6.7 7.3
10/19/2017 4.0 5.6 5.0 4.6 5.9 5.1 7.1 6.6 7.3
2/12/2018 5.7 7.0 6.8 6.2 7.5 6.5 8.8 8.0 8.9
6/7/2018 3.7 5.2 4.4 4.6 4.4 5.3 5.1 7.2 7.0
2/15/2019 6.5 7.4 7.6 7.3 9.7
6/6/2019 3.8 5.5 4.5 4.4 5.3 6.9 7.5
0
1
2
3
4
5
6
7
8
9
10
6/1/2017 8/31/2017 11/30/2017 3/1/2018 6/1/2018 8/31/2018 11/30/2018 3/2/2019 6/1/2019 8/31/2019 Depth to Water (feet) Date
MW-1
MW-2
PZ-1
PZ-2
PZ-3
PZ-4
PZ-5
PZ-6
PZ-7
6/25/2019 Miller Groundwater Engineering, LLC
Is there an approved/signed version of this to include? (should be if it was included in the utility plan set - let me know if you need assistance locating)HDS RESPONSE: THISSHEET HAS BEENREPLACED WITH THESIGNED/SCANNED SHEET
C2-10C100tc2 yr (min)tc100-yr (min)I2(in/hr)I100(in/hr)Q2(cfs)Q100(cfs)DESIGN POINTRunoff CoefficientTime of ConcentrationRainfall IntensityAREA (acres)TRIBUTARY SUB-BASINPeak RunoffB7B7 0.27 0.81 1.00 5.00 5.00 2.85 9.95 0.62 2.64B8B8 0.40 0.78 0.98 5.27 5.00 2.74 9.95 0.86 3.90B9B9 2.29 0.81 1.00 5.00 13.07 1.87 6.90 1.93 8.89B10B10 0.48 0.66 0.82 5.00 5.00 2.85 9.95 0.90 3.91B11B11 2.47 0.73 0.91 11.21 8.85 2.11 8.09 3.82 18.29B12B12 0.41 0.26 0.33 6.00 5.57 2.64 9.40 0.28 1.27B13B13 0.38 0.87 1.00 5.00 5.00 2.85 9.95 0.95 3.81B14B14 0.36 0.86 1.00 5.00 5.00 2.85 9.95 0.88 3.59B15B15 0.89 0.80 1.00 6.29 5.67 2.60 9.36 1.86 8.31B16B16 0.54 0.91 1.00 5.00 5.00 2.85 9.95 1.41 5.38B17B17 0.35 0.79 0.99 5.40 5.00 2.72 9.95 0.76 3.48B18B18 0.43 0.67 0.84 8.49 6.56 2.36 8.96 0.68 3.24B19B19 0.43 0.69 0.87 8.25 6.26 2.38 9.09 0.71 3.38B20B20 2.94 0.34 0.43 21.24 19.62 1.56 5.67 1.57 7.12B Total 19.4828.44 126.55C1C1 1.30 0.45 0.56 14.81 10.70 2.05 7.52 1.41 6.48C2C2 0.14 0.53 0.67 12.07 5.00 2.85 9.95 0.10 0.42C3C3 0.83 0.25 0.31 5.00 6.12 2.38 9.15 1.39 6.66C4C4 0.22 0.70 0.88 8.23 5.00 2.85 9.95 0.47 2.07C5C5 1.20 0.77 0.96 5.00 10.27 2.11 7.64 1.05 4.74C Total 3.684.42 20.37D1AD1A 0.70 0.57 0.71 7.86 6.93 2.41 8.80 0.70 3.18D1D1 0.73 0.42 0.52 6.39 5.00 2.59 9.95 1.40 6.75D2D2 0.65 0.42 0.52 7.94 5.00 2.77 9.95 1.57 6.50D3D3 0.45 0.25 0.31 5.00 6.81 2.42 8.85 0.61 2.81D4D4 0.16 0.61 0.76 8.39 5.00 2.85 9.95 0.33 1.42D5D5 0.43 0.87 1.00 5.07 6.88 2.36 8.82 0.61 2.85D6D6 0.10 0.70 0.87 5.00 5.00 2.59 9.95 0.20 0.94D7D7 0.09 0.73 0.92 6.38 5.00 2.85 9.95 0.21 0.87D8D8 0.72 0.63 0.78 11.58 5.00 2.69 9.95 1.67 7.15D9D9 0.61 0.83 1.00 5.00 9.99 2.09 7.72 0.79 3.67D10D10 0.16 0.65 0.81 11.91 5.00 2.68 9.95 0.28 1.30D11D11 0.88 0.89 1.00 5.83 10.39 2.06 7.61 1.17 5.42D12D12 0.76 0.86 1.00 5.61 5.04 2.66 9.67 1.80 7.3718-1000-00 Rational Calcs (FC).xlsx Page 18 of 19Highland Development ServicesAREA MATCHESPROPOSED BASIN D1AREA MATCHESPROPOSED BASIN D2-D3AREA MATCHESPROPOSED BASIN D5-D7NORTHFIELD RATIONAL CALCS SUMMARY SHEET
C2-10C100tc2 yr (min)tc100-yr (min)I2(in/hr)I100(in/hr)Q2(cfs)Q100(cfs)DESIGN POINTRunoff CoefficientTime of ConcentrationRainfaill IntensityAREA (acres)TRIBUTARY SUB-BASINPeak RunoffD13D13 0.28 0.67 0.83 5.72 5.00 2.85 9.95 0.24 1.06D14D14 2.50 0.31 0.39 5.00 13.75 1.89 6.75 1.33 5.90D15D15 0.44 0.72 0.89 14.39 5.53 2.61 9.42 0.84 3.80D Total 9.6513.75 60.99E1E1 0.48 0.28 0.35 14.39 5.11 2.56 9.63 1.01 4.62E2E2 0.66 0.82 1.00 6.61 5.33 2.53 9.52 1.43 6.32E3E3 1.55 0.85 1.00 6.88 13.92 1.92 6.71 2.50 10.42E4E4 1.95 0.84 1.00 13.92 15.22 1.75 6.43 2.50 11.50E5E5 0.58 0.73 0.91 17.04 6.38 2.40 9.03 1.16 5.28E6E6 0.56 0.83 1.00 8.05 6.18 2.42 9.12 1.13 5.15E7E7 0.75 0.83 1.00 7.87 6.94 2.34 8.80 1.31 6.19E8E8 0.60 0.75 0.93 8.67 7.42 2.28 8.61 0.97 4.58E9E9 0.39 0.71 0.89 9.31 5.15 2.85 9.95 0.91 3.58E10E10 0.24 0.81 1.00 5.00 5.00 3.82 13.32 0.80 3.24E Total 7.7913.74 60.88Overall 58.7087.03 387.81*NOTE - Flows represented above are to the design point and do not account for any excess flow from another basin. Please refer to the Inlet Summary Sheet for overflow.18-1000-00 Rational Calcs (FC).xlsx Page 19 of 19Highland Development ServicesAREA MATCHESPROPOSED BASIN D8AREA MATCHESPROPOSED BASIN D9
A11A12A14A15A18A3A4A6A9B1B10B11B12B17B18B19B2B20B3B4B6B8B9C1C2C3C4C5D13D14D3D4D5D6D7D1AD1OPA1OPA3OPA4OPB1OPB2OPB3OP-MHA4OP-MHA6OP-MHA7OP-MHB2OP-MHB5PA1PA10PA11PA12PA13PA14PA15PA16PA17PA2PA3PA4PA5PA6PA7PA8PB1PB10PB11PB12PB13PB14PB15PB16PB17PB18PB19PB2PB20PB3PB4PB5PB6PB7PB8PB9PC1PC2PC3PC4PC5PC6PC7PD5PD6PD7PD8PD11PD12PD13PE1PE2PA9PD9PD10PD1PD2PD3PD4OutB2OutA4OutA3OutB3OutB1OutD1OutC1OutA1IA1IA2IA3IA4IA5IA6IB1IB10IB11IB2IB3IB4IB5IB6IB7IB8IB9IC1IC2IC3IC4ID3ID4ID5ID6IE1IE2MHA1MHA2MHA3MHA5MHB1MHB3MHB4MHB6MHC1MHC2MHD2MHD4MHD5OA2OA3-Stage1OA3-Stage2OA4-Stage1OA4-Stage2OB1-Stage1OB1-Stage2OB2-Stage1OB2-Stage2OB3-Stage1OB3-Stage2OC1OD1MHD3ID1AID1ID2MHD1OA1-Stage1OA1-Stage2Out2Out1Out3MHB2MHA4MHB5MHA7MHA6VB3VB2VB1VA2VA1VC1VD1CoFC_100-yr03/11/2019 00:05:00SWMM 5.1Page 1A11A12A14A15A18A3A4A6A9B1B10B11B12B17B18B19B2B20B3B4B6B8B9C1C2C3C4C5D13D14D3D4D5D6D7D1AD1OPA1OPA3OPA4OPB1OPB2OPB3OP-MHA4OP-MHA6OP-MHA7OP-MHB2OP-MHB5PA1PA10PA11PA12PA13PA14PA15PA16PA17PA2PA3PA4PA5PA6PA7PA8PB1PB10PB11PB12PB13PB14PB15PB16PB17PB18PB19PB2PB20PB3PB4PB5PB6PB7PB8PB9PC1PC2PC3PC4PC5PC6PC7PD5PD6PD7PD8PD11PD12PD13PE1PE2PA9PD9PD10PD1PD2PD3PD4OutB2OutA4OutA3OutB3OutB1OutD1OutC1OutA1IA1IA2IA3IA4IA5IA6IB1IB10IB11IB2IB3IB4IB5IB6IB7IB8IB9IC1IC2IC3IC4ID3ID4ID5ID6IE1IE2MHA1MHA2MHA3MHA5MHB1MHB3MHB4MHB6MHC1MHC2MHD2MHD4MHD5OA2OA3-Stage1OA3-Stage2OA4-Stage1OA4-Stage2OB1-Stage1OB1-Stage2OB2-Stage1OB2-Stage2OB3-Stage1OB3-Stage2OC1OD1MHD3ID1AID1ID2MHD1OA1-Stage1OA1-Stage2Out2Out1Out3MHB2MHA4MHB5MHA7MHA6VB3VB2VB1VA2VA1VC1VD1CoFC_100-yrA11A14A15A18A3A4A6A9B1B10B11B12B17B18B19B2B20B3B4B6B8B9C1C2C3C4C5D14D3D4D5D6D7D1AD1A12D9D10D12E6E8OPA4OPA2OPA1OPB3OPB2OPB1OP-MHA4OP-IA03OP-IA01OP-MHB05OP-MHB01PA14PA07PA06PA05PA17PA03PA02PA01PA04PA13PA12PA15PA11PA10PA16PA09PB11PB15PB14PB13PB12PB04PB03PB02PB20PB18PB19PB10PB01PB109PB08PB07PB06PB16PB17PB05PC1PC2PC3PC4PC5PC6PC7PD5PD6PD7PD8PD11PD12PD13PE1PE2PA08PD9PD10PD1PD2PD3PD4PD14PD15PD16PD17OutB2OutA1OutA2OutB1OutD1OutC1OutA4OutB3IA07IA06IA08IA09IA04IA02IB06IB11IB12IB05IB04IB03IB09IB10IB08IB07IB13FESC01IC01IC03IC02ID04ID03ID02ID01IE02IE01MHA04MHA03MHA02MHA01MHB06MHB03MHB02MHB04FESC02MHC02MHD04MHD02MHD01OA3OA2-Stage1OA2-Stage2OA1-Stage1OA1-Stage2OB3-Stage1OB3-Stage2OB2-Stage1OB2-Stage2OB1-Stage1OB1-Stage2OC1OD1MHD03ID09ID08ID05MHD05OA4-Stage1OA4-Stage2IA05IA03IA01IB01IB02FESD06ID06FESD05MHD01AOut2Out1Out3VB3VB2VB1VA2VA1VC1VD1CoFC_100-yrPROPOSEDNORTHFIELDCOMMONS SITE
Northfield SWMM Output_2019-10-15.rpt FESD06 JUNCTION 9.23 9.23 0 00:40 0.107 0.107 -0.016 ID06 JUNCTION 1.21 10.28 0 00:40 0.0119 0.119 0.024 FESD05 JUNCTION 11.14 11.14 0 00:40 0.132 0.132 0.005 MHD01A JUNCTION 0.00 20.23 0 00:40 0 0.25 -0.004 Out2 OUTFALL 0.00 7.49 0 05:08 0 1.08 0.000 Out1 OUTFALL 0.00 4.55 0 00:31 0 0.613 0.000 Out3 OUTFALL 0.00 19.63 0 00:40 0 0.365 0.000 VB3 STORAGE 11.44 57.73 0 00:40 0.162 0.65 0.910 VB2 STORAGE 2.26 18.07 0 00:40 0.0223 0.11 0.015 VB1 STORAGE 6.57 48.96 0 00:36 0.146 1.24 0.240 VA2 STORAGE 19.99 49.73 0 00:40 0.238 0.52 0.082 VA1 STORAGE 8.84 49.86 0 00:40 0.162 1.15 4.181 VC1 STORAGE 5.30 20.73 0 00:40 0.0728 0.25 0.252 VD1 STORAGE 4.91 44.51 0 00:42 0.128 0.619 0.250 ********************** Node Surcharge Summary ********************** Surcharging occurs when water rises above the top of the highest conduit. --------------------------------------------------------------------- Max. Height Min. Depth Hours Above Crown Below Rim Node Type Surcharged Feet Feet --------------------------------------------------------------------- IA07 JUNCTION 1.17 3.186 0.374 IA06 JUNCTION 1.92 3.743 0.417 IA08 JUNCTION 1.09 4.173 0.027 IA09 JUNCTION 5.48 3.104 0.186 IA04 JUNCTION 5.53 3.299 4.381 IA02 JUNCTION 5.45 4.904 0.206 IB06 JUNCTION 5.47 3.325 0.345 IB11 JUNCTION 5.33 1.830 1.470 IB12 JUNCTION 5.25 1.498 1.152 IB05 JUNCTION 5.48 3.945 1.105 IB04 JUNCTION 5.48 3.411 1.229 IB03 JUNCTION 5.48 3.615 1.785 IB09 JUNCTION 5.47 3.462 0.048 IB10 JUNCTION 2.74 0.352 2.848 IB08 JUNCTION 3.90 4.295 0.695 IB07 JUNCTION 3.11 3.974 0.696 IC01 JUNCTION 1.17 0.131 2.669 IC02 JUNCTION 1.57 0.200 3.300 IE02 JUNCTION 0.12 0.241 3.459 IE01 JUNCTION 0.60 0.398 3.502 MHA04 JUNCTION 1.25 3.277 0.713 MHA03 JUNCTION 1.24 3.156 1.294 MHA02 JUNCTION 5.48 3.828 1.892 MHA01 JUNCTION 5.54 3.737 4.923 MHB06 JUNCTION 5.48 3.824 2.476 MHB03 JUNCTION 5.55 4.237 5.163 MHB02 JUNCTION 5.57 4.972 2.448 MHB04 JUNCTION 5.38 2.319 4.481 FESC02 JUNCTION 2.61 0.420 2.380Page 7PEAK FLOW FOR NORTHFIELDSUB-BASINS D1-D14NORTHFIELD EPA SWMM OUTPUT
REDWOOD STREETDRY CREEKLA
K
E
CA
NA
L
D
I
TC
H
FUTURE LEMAY AVENUEN. LEMAY AVENUECOLLAMER DRIVEPIONEER TRAIL ROADSTEELEY DRIVELANDMARK WAY
N. LEMAY AVENUE RAINGARDEND1SC
H
LAG
E
L
S
T
R
E
E
T
FUTURESUNIGAROADPOND B3POND A2POND A1POND B2POND CPOND B1POND DRAIN GARDEN B1E. SUNIGA ROADSUNIGA ROAD AREADETENTION / LANDSCAPE AREAPROPOSED SINGLE FAMILY AREAPROPOSED MULTI-FAMILY AREAAREA CONTRIBUTING TO LID TREATMENTLEGEND0100'20010050100SCALE: 1" = REVISIONNO.BY DATE
HIGHLAND
DEVELOPMENT SERVICES
6355 FAIRGROUNDS AVENUE, SUITE 100 | WINDSOR, CO 80550
PHONE: 970.674.7550 | FAX: 970.674.7568 | www.Highland-DS.comPREPARED BY OR UNDER THEDIRECT SUPERVISION OF:FOR AND ON BEHALF OF HIGHLANDDEVELOPMENT SERVICESREVIEW SETNOT FORCONSTRUCTIONOFSHEETDRAWN BYCHECKED BYDATESCALE (H)HDS PROJECT #SCALE (V)NORTHFIELD
LID & WQ TREATMENT AREAS EXHIBIT10/15/191" = 100'N/AKRBJTC18-1000-00----11NWESPROPOSED COMMERCIAL AREAAREA CONTRIBUTING TO EXTENDEDDETENTION BASIN WATER QUALITY TREATMENTAREA CONTRIBUTING TO SNOUT HOODWATER QUALITY TREATMENT
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
Low Impact Development Summary
Sq-Ft Acres
Impervious Area
(sq-ft)
% of Impervious
Area Requiring
Treatment
Impervious Area
Requiring
Treatment
537,816 12.35 330,931 50% 165,465
1,189,400 27.30 794,336 75% 595,752
40,986 0.94 20,720 75% 15,540
304,148 6.98 248,720 0% N/A
445,251 10.22 0 0% N/A
2,517,600 57.80 1,394,707 - 776,757
LID
Facility
Contributing
Basins
Area Drainage
to LID
(sq-ft)
% Impervious
Impervious
Area Treated
(sq-ft)
WQCV12-hr
(watershed inches)
WQCV12-hr
(cu-ft)
Treatment
Method
A2 A1+…+A12 427,599 66.5% 302,122 0.21 7,414 Infiltration Gallery
B1 B13+…B17 110,074 79.3% 93,219 0.26 2,378 Rain Garden
B2 B10+…+B12 146,450 55.7% 86,485 0.18 2,173 Infiltration Gallery
B3 B1+…+B9 426,521 54.7% 251,577 0.18 6,243 Infiltration Gallery
D1 D8+…+D13 148,227 61.5% 98,626 0.19 2,384 Rain Garden
EDB Pond Contributing
Basins
Drainage Area
(sq-ft)
Drainage Area
(sq-ft)% Impervious WQCV40-hr
(watershed inches)
WQCV40-hr
(ac-ft)
Pond A A18 131,657 3.022 12.5% 0.08 0.024
Pond B B18+…+B20 165,673 3.803 22.5% 0.13 0.048
Pond C C1+…+C5 160,137 3.676 38.2% 0.18 0.064
Pond D D1+…+D7+D14 253,037 5.809 32.5% 0.16 0.092
776,757
832,029
107.1%
Area (sq-ft) Area (acres) Treatment Ratio
1,258,871 28.90 50.0%
710,504 16.31 28.2%
322,629 7.41 12.8%
126,940 2.91 5.0%
2,418,944 55.53 96.1%
98,790 2.27 3.9%
2,517,734 57.80
Total Area unable to be Treated
(Basins A13, A14, portion of A16, & A17)
Total Treated Area
Total Improvement Area
Water Quality Area Treatment Summary
Description
Total Area Treated by Snout (Lemay - Basins A15 & D15)
Standard Water Quality Areas
Total Area Treated by LID
Total Area Treated by EDB
Total Area Treated by Snout (Suniga)
Description
Single Family Area
Multifamily Area
Commercial Area
Suniga Road (no LID treatment)
Northfield
Low Impact Development
Total % Treatment
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 Treated (sq-ft)
Total Impervious Area Required for LID Treatment (sq-ft)
LID Treatment Summary
LID Treatment Areas
Detention / Landscape Areas (no LID treatment)
J.Claeys
Highland Development Services
18-1000-00
October 15, 2019
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
Totals
Appendix B
APPENDIX B – SWMM INPUT/OUTPUT
Northfield Mercy Housing
PROPOSED DRAINAGE SUMMARY
Design Engineer:A. Bartel
Design Firm:Highland Development Services
Project Number:21-1037-00
Date:
SWMM INPUT SUMMARY TABLE
D1 D1 3.15 137,252 48.5%581 236 1.34%
D2 D2 0.07 3,228 100.0%113 29 1.62%
D5 D5 0.81 35,339 40.7%363 97 1.00%
D6 D6 0.16 6,832 42.5%172 40 1.08%
D7 D7 1.91 83,096 69.8%762 109 0.84%
D8 D8 0.28 11,992 7.6%58 206 7.84%
D9 D9 2.50 108,741 3.9%629 173 1.03%
D8+D9 D8+D9 2.77 120,732 4.3%629 173 1.03%
E6 E5, E6 1.15 50,017 81.8%502 100 0.50%
E8 E7, E8 1.35 58,860 67.8%497 118 0.50%
Slope %Length
(ft)
Width
(ft)
September 8, 2021
SWMM
SUBCATCHMENT
BASIN ID
TRIBUTARY
SUB-BASINS
AREA
(acres)
AREA
(sq ft)
Percent
Impervious
21-1037-00 Rational Calcs (FC).xlsx Page 7 of 7 Highland Development Services
18-1000-00 NF Commons SWMM.inp[TITLE];;Project Title/NotesNorthfield100-yr Storm Routing9/27/19[OPTIONS];;Option ValueFLOW_UNITS CFSINFILTRATION HORTONFLOW_ROUTING DYNWAVELINK_OFFSETS DEPTHMIN_SLOPE 0ALLOW_PONDING NOSKIP_STEADY_STATE NOSTART_DATE 03/11/2019START_TIME 00:00:00REPORT_START_DATE 03/11/2019REPORT_START_TIME 00:00:00END_DATE 03/11/2019END_TIME 06:00:00SWEEP_START 01/01SWEEP_END 12/31DRY_DAYS 0REPORT_STEP 00:05:00WET_STEP 00:05:00DRY_STEP 00:05:00ROUTING_STEP 0:01:00 RULE_STEP 00:00:00INERTIAL_DAMPING PARTIALNORMAL_FLOW_LIMITED BOTHFORCE_MAIN_EQUATION H-WVARIABLE_STEP 0.75LENGTHENING_STEP 0MIN_SURFAREA 12.566MAX_TRIALS 8HEAD_TOLERANCE 0.005SYS_FLOW_TOL 5LAT_FLOW_TOL 5MINIMUM_STEP 0.5THREADS 1[EVAPORATION];;Data Source Parameters;;-------------- ----------------CONSTANT 0.0DRY_ONLY NO[RAINGAGES] Page 1
18-1000-00 NF Commons SWMM.inp;;Name Format Interval SCF Source ;;-------------- --------- ------ ------ ----------CoFC_100-yr INTENSITY 0:05 1.0 TIMESERIES CoFC_100-yr [SUBCATCHMENTS];;Name Rain Gage Outlet Area %Imperv Width %Slope CurbLen SnowPack ;;-------------- ---------------- ---------------- -------- -------- -------- -------- -------- ----------------D02 CoFC_100-yr ID03 0.074 100 29 1.62 0 D03 CoFC_100-yr ID04 0.074 100 28 1.62 0 D05 CoFC_100-yr FESD02 0.811 40.7 97 1.00 0 D06 CoFC_100-yr ID06 .16 42.5 40 1.08 0 D07 CoFC_100-yr FESD03 1.908 69.8 109 0.84 0 D14 CoFC_100-yr VD1 2.77 4.3 173 1.03 0 E06 CoFC_100-yr IE02 1.15 81.8 100 0.5 0 E08 CoFC_100-yr IE01 1.35 67.8 118 0.5 0 D01 CoFC_100-yr ID01 3.15 48.5 236 1.34 0 D04 CoFC_100-yr ID05 0.235 17.2 50 1.78 0 [SUBAREAS];;Subcatchment N-Imperv N-Perv S-Imperv S-Perv PctZero RouteTo PctRouted ;;-------------- ---------- ---------- ---------- ---------- ---------- ---------- ----------D02 0.01 0.1 .1 .3 1 OUTLET D03 0.01 0.1 .1 .3 1 OUTLET D05 0.01 0.1 .1 .3 1 OUTLET D06 0.01 0.1 .1 .3 1 OUTLET D07 0.01 0.1 .1 .3 1 OUTLET D14 0.01 0.1 .1 .3 1 OUTLET E06 0.01 0.1 .1 .3 1 OUTLET E08 0.01 0.1 .1 .3 1 OUTLET D01 0.01 0.1 0.1 0.3 1 OUTLET D04 0.01 0.1 0.1 0.3 1 OUTLET [INFILTRATION];;Subcatchment MaxRate MinRate Decay DryTime MaxInfil ;;-------------- ---------- ---------- ---------- ---------- ----------D02 3.0 0.5 6.48 7 0 D03 3.0 0.5 6.48 7 0 D05 3.0 0.5 4 7 0 D06 3.0 0.5 4 7 0 D07 3.0 0.5 4 7 0 D14 3.0 0.5 6.48 7 0 E06 3.0 0.5 4 7 0 E08 3.0 0.5 4 7 0 D01 3.0 0.5 4 7 0 D04 3.0 0.5 4 7 0 [JUNCTIONS];;Name Elevation MaxDepth InitDepth SurDepth Aponded ;;-------------- ---------- ---------- ---------- ---------- ----------FESD03 4952.21 1 0 0 0 FESD02 4955.43 1 0 0 0 Page 2
18-1000-00 NF Commons SWMM.inpID04 4951.21 6.35 0 0 0 ID03 4951.38 6.18 0 0 0 ID02 4951.86 4.27 0 0 0 ID06 4949.97 3.23 0 0 0 IE01 4944.6 6.6 0 0 0 IE02 4944.77 6.2 0 0 0 MHD03 4947.52 6.56 0 0 0 MHD01A 4949.83 3.97 0 0 0 MHD02 4948.10 6.19 0 0 0 MHD01 4949.41 5.81 0 0 0 OD1 4945.11 5.89 0 0 0 ID05 4950.26 4.68 0 0 0 ID01 4952.17 2.71 0 0 0 [OUTFALLS];;Name Elevation Type Stage Data Gated Route To ;;-------------- ---------- ---------- ---------------- -------- ----------------Out3 4943.69 TIMESERIES NECCO_A7 NO [STORAGE];;Name Elev. MaxDepth InitDepth Shape Curve Name/Params N/A Fevap Psi Ksat IMD ;;-------------- -------- ---------- ----------- ---------- ---------------------------- -------- -------- -------- --------VD1 4945.65 5.38 0 TABULAR Pond_D 0 0 [CONDUITS];;Name From Node To Node Length Roughness InOffset OutOffset InitFlow MaxFlow ;;-------------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------- ----------PD03 ID03 ID04 36 .012 0 0 0 0 PD06 MHD01 MHD02 278.26 .012 0 0 0 0 PD07 MHD02 MHD03 123.61 .012 0 0 0 0 PD08 MHD03 VD1 154.42 .016 0 0 0 0 PD13 OD1 IE02 48 .012 0 .1 0 0 PD09 FESD02 ID06 130.04 .012 0 0 0 0 PD10 ID06 MHD01A 17 .012 0 0 0 0 PD11 FESD03 MHD01A 14 .012 0 0 0 0 PD12 MHD01A VD1 65.47 .012 0 0 0 0 PE01 IE02 IE01 65 .012 0 0 0 0 PE02 IE01 Out3 22 .016 0 0 0 0 PD04 ID04 ID05 201.22 0.012 0 0 0 0 PD05 ID05 MHD01 181.20 0.012 0 0 0 0 PD02 ID02 ID03 102.27 0.012 0 0 0 0 PD01 ID01 ID02 66.90 0.012 0 0 0 0 [ORIFICES];;Name From Node To Node Type Offset Qcoeff Gated CloseTime ;;-------------- ---------------- ---------------- ------------ ---------- ---------- -------- ----------OutD1 VD1 OD1 SIDE -.51 0.65 NO 0 [XSECTIONS];;Link Shape Geom1 Geom2 Geom3 Geom4 Barrels Culvert ;;-------------- ------------ ---------------- ---------- ---------- ---------- ---------- ---------- Page 3
18-1000-00 NF Commons SWMM.inpPD03 CIRCULAR 2.5 0 0 0 1 PD06 CIRCULAR 2.5 0 0 0 1 PD07 CIRCULAR 2.5 0 0 0 1 PD08 HORIZ_ELLIPSE 2.000 3.167 4 0 1 PD13 CIRCULAR 1.5 0 0 0 1 PD09 CIRCULAR 1 0 0 0 1 PD10 CIRCULAR 1.5 0 0 0 1 PD11 CIRCULAR 1.5 0 0 0 1 PD12 CIRCULAR 1.5 0 0 0 1 PE01 CIRCULAR 2.5 0 0 0 1 PE02 CIRCULAR 2.5 0 0 0 1 PD04 CIRCULAR 2.5 0 0 0 1 PD05 CIRCULAR 2.5 0 0 0 1 PD02 CIRCULAR 2.0 0 0 0 1 PD01 CIRCULAR 2.0 0 0 0 1 OutD1 CIRCULAR 0.3958 0 0 0[CURVES];;Name Type X-Value Y-Value ;;-------------- ---------- ---------- ----------;Pond DPond_D Storage 0 0 Pond_D .38 953 Pond_D 0.88 4839 Pond_D 1.38 8716 Pond_D 1.88 10860 Pond_D 2.38 19723 Pond_D 2.88 29964 Pond_D 3.38 42821 Pond_D 3.88 52864 Pond_D 4.38 59809 Pond_D 4.88 65735 Pond_D 5.38 74113 [TIMESERIES];;Name Date Time Value ;;-------------- ---------- ---------- ----------;CoFC Rainfall DataCoFC_100-yr 0:5 1.00 CoFC_100-yr 0:10 1.14 CoFC_100-yr 0:15 1.33 CoFC_100-yr 0:20 2.23 CoFC_100-yr 0:25 2.84 CoFC_100-yr 0:30 5.49 CoFC_100-yr 0:35 9.95 CoFC_100-yr 0:40 4.12 CoFC_100-yr 0:45 2.48 CoFC_100-yr 0:50 1.46 CoFC_100-yr 0:55 1.22 CoFC_100-yr 0:60 1.06 CoFC_100-yr 1:05 1.00 Page 4Pond D Outlet Structure100-yr Orifice Diameter
18-1000-00 NF Commons SWMM.inpCoFC_100-yr 1:10 0.95 CoFC_100-yr 1:15 0.91 CoFC_100-yr 1:20 0.87 CoFC_100-yr 1:25 0.84 CoFC_100-yr 1:30 0.81 CoFC_100-yr 1:35 0.78 CoFC_100-yr 1:40 0.75 CoFC_100-yr 1:45 0.73 CoFC_100-yr 1:50 0.71 CoFC_100-yr 1:55 0.69 CoFC_100-yr 2:00 0.67 ;NECCO_A7 FILE "NECCO A7 HGL.dat"[REPORT];;Reporting OptionsSUBCATCHMENTS ALLNODES ALLLINKS ALL[TAGS][MAP]DIMENSIONS -3908.103 305.049 14377.949 10305.049Units Feet[COORDINATES];;Node X-Coord Y-Coord ;;-------------- ------------------ ------------------FESD03 6155.843 3257.701 FESD02 4380.843 3320.872 ID04 3377.528 2581.392 ID03 3232.605 2581.392 ID02 2801.551 2578.915 ID06 6085.239 3313.441 IE01 7717.391 3716.421 IE02 7717.391 3460.461 MHD03 6132.308 3090.482 MHD01A 6155.843 3312.202 MHD02 6129.831 2572.722 MHD01 4970.445 2575.199 OD1 7711.599 3239.121 ID05 4216.459 2577.632 ID01 2590.979 2767.191 Out3 7678.866 3850.518 VD1 7380.785 3141.386 [VERTICES];;Link X-Coord Y-Coord ;;-------------- ------------------ ------------------ Page 5
18-1000-00 NF Commons SWMM.inp[Polygons];;Subcatchment X-Coord Y-Coord ;;-------------- ------------------ ------------------D02 3022.186 2334.342 D03 3653.581 2288.346 D05 4047.074 3141.975 D05 4047.074 3141.975 D05 4047.074 3141.975 D05 4041.798 3139.337 D05 4041.798 3139.337 D05 4039.160 3139.337 D05 4025.971 3152.527 D05 4049.712 3147.251 D05 4047.074 3136.700 D05 4041.798 3139.337 D06 5929.168 3189.774 D06 5926.530 3200.325 D06 5929.168 3195.049 D06 5939.720 3189.774 D06 5926.530 3187.136 D06 5923.892 3197.687 D07 5929.438 3037.799 D07 5947.903 3048.350 D07 5947.903 3037.799 D07 5937.351 3037.799 D07 5937.351 3050.988 D14 9344.320 2878.413 E06 8089.409 3467.568 E06 8099.960 3454.379 E06 8084.133 3457.017 E06 8092.047 3470.206 E08 8113.150 3731.355 E08 8121.063 3731.355 E08 8126.339 3731.355 E08 8113.150 3715.528 E08 8097.323 3731.355 E08 8102.598 3731.355 D01 2279.456 2839.653 D01 2568.064 2764.095 D04 4137.238 2587.721 D04 3993.622 2769.634 [SYMBOLS];;Gage X-Coord Y-Coord ;;-------------- ------------------ ------------------CoFC_100-yr 4485.211 4295.822 [PROFILES];;Name Links ;;-------------- ---------- Page 6
18-1000-00 NF Commons SWMM.inp"South Main " PD01 PD02 PD03 PD04 PD05"South Main " PD06 PD07 PD08 OutD1 PD13"South Main " PE01 PE02 Page 7
18-1000-00 NF Commons SWMM.rpt EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.013) -------------------------------------------------------------- NF Commons 100-yr Storm Routing 9/8/21 ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. ********************************************************* **************** Analysis Options **************** Flow Units ............... CFS Process Models: Rainfall/Runoff ........ YES RDII ................... NO Snowmelt ............... NO Groundwater ............ NO Flow Routing ........... YES Ponding Allowed ........ NO Water Quality .......... NO Infiltration Method ...... HORTON Flow Routing Method ...... DYNWAVE Surcharge Method ......... EXTRAN Starting Date ............ 03/11/2019 00:00:00 Ending Date .............. 03/11/2019 06:00:00 Antecedent Dry Days ...... 0.0 Report Time Step ......... 00:05:00 Wet Time Step ............ 00:05:00 Dry Time Step ............ 00:05:00 Routing Time Step ........ 60.00 sec Variable Time Step ....... YES Maximum Trials ........... 8 Number of Threads ........ 1 Head Tolerance ........... 0.005000 ft ************************** Volume Depth Runoff Quantity Continuity acre-feet inches ************************** --------- ------- Total Precipitation ...... 3.572 3.669 Evaporation Loss ......... 0.000 0.000 Infiltration Loss ........ 1.046 1.074 Surface Runoff ........... 2.503 2.572 Final Storage ............ 0.046 0.047 Page 1
18-1000-00 NF Commons SWMM.rpt Continuity Error (%) ..... -0.640 ************************** Volume Volume Flow Routing Continuity acre-feet 10^6 gal ************************** --------- --------- Dry Weather Inflow ....... 0.000 0.000 Wet Weather Inflow ....... 2.503 0.816 Groundwater Inflow ....... 0.000 0.000 RDII Inflow .............. 0.000 0.000 External Inflow .......... 0.000 0.000 External Outflow ......... 1.127 0.367 Flooding Loss ............ 0.000 0.000 Evaporation Loss ......... 0.000 0.000 Exfiltration Loss ........ 0.000 0.000 Initial Stored Volume .... 0.000 0.000 Final Stored Volume ...... 1.377 0.449 Continuity Error (%) ..... -0.018 ************************* Highest Continuity Errors ************************* Node MHD03 (1.73%) Node MHD02 (1.32%) *************************** Time-Step Critical Elements *************************** Link PE02 (52.22%) Link PD11 (47.14%) ******************************** Highest Flow Instability Indexes ******************************** Link PE02 (6) Link PE01 (4) Link PD13 (3) ************************* Routing Time Step Summary ************************* Minimum Time Step : 0.50 sec Average Time Step : 1.22 sec Maximum Time Step : 60.00 sec Percent in Steady State : 0.00 Average Iterations per Step : 2.04 Percent Not Converging : 0.40 Page 2
18-1000-00 NF Commons SWMM.rpt *************************** Subcatchment Runoff Summary *************************** ------------------------------------------------------------------------------------------------------------------------------ Total Total Total Total Imperv Perv Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Runoff Runoff Coeff Subcatchment in in in in in in in 10^6 gal CFS ------------------------------------------------------------------------------------------------------------------------------ D02 3.67 0.00 0.00 0.00 3.59 0.00 3.59 0.01 0.74 0.979 D03 3.67 0.00 0.00 0.00 3.59 0.00 3.59 0.01 0.74 0.979 D05 3.67 0.00 0.00 1.19 1.46 1.00 2.46 0.05 4.89 0.671 D06 3.67 0.00 0.00 1.12 1.53 1.02 2.55 0.01 1.19 0.694 D07 3.67 0.00 0.00 0.61 2.51 0.50 3.01 0.16 13.79 0.821 D14 3.67 0.00 0.00 1.90 0.15 1.62 1.77 0.13 5.85 0.483 E06 3.67 0.00 0.00 0.36 2.94 0.32 3.26 0.10 9.53 0.888 E08 3.67 0.00 0.00 0.65 2.44 0.54 2.98 0.11 9.91 0.812 D01 3.67 0.00 0.00 1.05 1.74 0.86 2.60 0.22 19.68 0.709 D04 3.67 0.00 0.00 1.62 0.62 1.45 2.07 0.01 1.33 0.563 ****************** Node Depth Summary ****************** --------------------------------------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- FESD03 JUNCTION 0.13 0.55 4952.76 0 00:40 0.55 FESD02 JUNCTION 0.12 0.57 4956.00 0 00:40 0.57 ID04 JUNCTION 0.33 1.56 4952.77 0 00:40 1.51 ID03 JUNCTION 0.33 1.54 4952.92 0 00:40 1.51 ID02 JUNCTION 0.35 1.73 4953.59 0 00:40 1.70 ID06 JUNCTION 0.18 0.92 4950.89 0 00:40 0.91 IE01 JUNCTION 2.00 5.49 4950.09 0 00:39 3.71 IE02 JUNCTION 1.85 2.66 4947.43 0 00:44 2.63 MHD03 JUNCTION 1.63 2.01 4949.53 0 02:20 2.00 MHD01A JUNCTION 0.20 0.95 4950.78 0 00:40 0.95 MHD02 JUNCTION 1.19 1.56 4949.66 0 00:41 1.42 MHD01 JUNCTION 0.35 1.59 4951.00 0 00:41 1.46 OD1 JUNCTION 1.52 3.74 4948.85 0 00:38 2.30 ID05 JUNCTION 0.34 1.60 4951.86 0 00:40 1.51 ID01 JUNCTION 0.36 1.83 4954.00 0 00:40 1.82 Out3 OUTFALL 2.88 3.69 4947.38 0 00:44 3.68 VD1 STORAGE 3.34 3.87 4949.52 0 02:21 3.87 Page 3Pond D 100-yr WSE
18-1000-00 NF Commons SWMM.rpt ******************* Node Inflow Summary ******************* ------------------------------------------------------------------------------------------------- Maximum Maximum Lateral Total Flow Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent ------------------------------------------------------------------------------------------------- FESD03 JUNCTION 13.79 13.79 0 00:40 0.156 0.156 0.001 FESD02 JUNCTION 4.89 4.89 0 00:40 0.0542 0.0542 0.000 ID04 JUNCTION 0.74 21.05 0 00:40 0.00722 0.237 -0.002 ID03 JUNCTION 0.74 20.35 0 00:40 0.00722 0.23 -0.006 ID02 JUNCTION 0.00 19.64 0 00:40 0 0.222 0.003 ID06 JUNCTION 1.19 6.05 0 00:40 0.0111 0.0653 -0.000 IE01 JUNCTION 9.91 24.29 0 00:39 0.109 0.366 -0.233 IE02 JUNCTION 9.53 10.39 0 00:38 0.102 0.258 0.281 MHD03 JUNCTION 0.00 21.76 0 00:41 0 0.248 1.762 MHD01A JUNCTION 0.00 19.73 0 00:40 0 0.221 -0.010 MHD02 JUNCTION 0.00 22.17 0 00:41 0 0.251 1.334 MHD01 JUNCTION 0.00 22.30 0 00:41 0 0.25 -0.108 OD1 JUNCTION 0.00 3.12 0 00:38 0 0.157 0.064 ID05 JUNCTION 1.33 22.38 0 00:40 0.0132 0.25 -0.001 ID01 JUNCTION 19.68 19.68 0 00:40 0.222 0.222 0.004 Out3 OUTFALL 0.00 33.77 0 00:38 0 0.367 0.000 VD1 STORAGE 5.85 44.65 0 00:41 0.133 0.598 0.956 ********************** Node Surcharge Summary ********************** Surcharging occurs when water rises above the top of the highest conduit. --------------------------------------------------------------------- Max. Height Min. Depth Hours Above Crown Below Rim Node Type Surcharged Feet Feet --------------------------------------------------------------------- IE01 JUNCTION 0.58 2.989 1.111 IE02 JUNCTION 0.09 0.159 3.541 OD1 JUNCTION 3.32 2.239 2.151 ********************* Node Flooding Summary ********************* No nodes were flooded. Page 4Pond D Peak Inflow
18-1000-00 NF Commons SWMM.rpt ********************** Storage Volume Summary ********************** -------------------------------------------------------------------------------------------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS -------------------------------------------------------------------------------------------------- VD1 54.398 33 0 0 71.557 43 0 02:21 1.20 *********************** Outfall Loading Summary *********************** ----------------------------------------------------------- Flow Avg Max Total Freq Flow Flow Volume Outfall Node Pcnt CFS CFS 10^6 gal ----------------------------------------------------------- Out3 99.90 3.22 33.77 0.367 ----------------------------------------------------------- System 99.90 3.22 33.77 0.367 ******************** Link Flow Summary ******************** ----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/ |Flow| Occurrence |Veloc| Full Full Link Type CFS days hr:min ft/sec Flow Depth ----------------------------------------------------------------------------- PD03 CONDUIT 20.34 0 00:40 6.39 0.67 0.62 PD06 CONDUIT 22.17 0 00:41 6.84 0.73 0.63 PD07 CONDUIT 21.76 0 00:41 8.26 0.71 0.68 PD08 CONDUIT 21.50 0 00:41 4.99 0.57 1.00 PD13 CONDUIT 2.93 0 00:37 2.04 0.36 1.00 PD09 CONDUIT 4.86 0 00:40 7.83 0.61 0.74 PD10 CONDUIT 6.13 0 00:40 5.37 0.59 0.62 PD11 CONDUIT 13.79 0 00:40 15.70 0.29 0.50 PD12 CONDUIT 19.78 0 00:40 12.82 0.69 0.82 PE01 CONDUIT 15.01 0 00:39 4.27 0.66 1.00 PE02 CONDUIT 33.77 0 00:38 7.52 0.50 1.00 PD04 CONDUIT 21.11 0 00:40 6.52 0.69 0.63 PD05 CONDUIT 22.30 0 00:41 6.79 0.73 0.63 PD02 CONDUIT 19.63 0 00:40 7.21 1.17 0.81 PD01 CONDUIT 19.64 0 00:40 6.69 1.18 0.88 OutD1 ORIFICE 1.19 0 05:51 1.00 Page 5Pond D 100-yr Detention Volume
18-1000-00 NF Commons SWMM.rpt *************************** Flow Classification Summary *************************** ------------------------------------------------------------------------------------- Adjusted ---------- Fraction of Time in Flow Class ---------- /Actual Up Down Sub Sup Up Down Norm Inlet Conduit Length Dry Dry Dry Crit Crit Crit Crit Ltd Ctrl ------------------------------------------------------------------------------------- PD03 1.00 0.00 0.00 0.00 0.52 0.48 0.00 0.00 0.64 0.00 PD06 1.00 0.00 0.00 0.00 0.79 0.21 0.00 0.00 0.71 0.00 PD07 1.00 0.00 0.00 0.00 0.84 0.16 0.00 0.00 0.05 0.00 PD08 1.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.09 0.00 PD13 1.00 0.00 0.00 0.00 0.99 0.00 0.00 0.01 0.03 0.00 PD09 1.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.97 0.00 PD10 1.00 0.00 0.00 0.00 0.52 0.48 0.00 0.00 0.65 0.00 PD11 1.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.98 0.00 PD12 1.00 0.00 0.00 0.00 0.81 0.19 0.00 0.00 0.93 0.00 PE01 1.00 0.00 0.00 0.00 0.94 0.06 0.00 0.00 0.00 0.00 PE02 1.00 0.00 0.00 0.00 0.97 0.03 0.00 0.00 0.05 0.00 PD04 1.00 0.00 0.00 0.00 0.53 0.47 0.00 0.00 0.89 0.00 PD05 1.00 0.00 0.00 0.00 0.52 0.48 0.00 0.00 0.89 0.00 PD02 1.00 0.00 0.00 0.00 0.50 0.50 0.00 0.00 0.26 0.00 PD01 1.00 0.00 0.00 0.00 0.57 0.43 0.00 0.00 0.88 0.00 ************************* Conduit Surcharge Summary ************************* ---------------------------------------------------------------------------- Hours Hours --------- Hours Full -------- Above Full Capacity Conduit Both Ends Upstream Dnstream Normal Flow Limited ---------------------------------------------------------------------------- PD08 0.11 0.11 5.36 0.01 0.01 PD13 3.32 3.32 3.85 0.01 0.01 PD12 0.01 0.01 5.43 0.01 0.01 PE01 0.09 0.09 0.57 0.01 0.01 PE02 0.57 0.57 4.28 0.01 0.01 PD02 0.01 0.01 0.01 0.05 0.01 PD01 0.01 0.01 0.01 0.05 0.01 Analysis begun on: Thu Sep 2 15:13:46 2021 Analysis ended on: Thu Sep 2 15:13:46 2021 Total elapsed time: < 1 sec Page 6
Appendix C
APPENDIX C – RATIONAL CALCULATIONS
Design Engineer:
Design Firm:
Project Number:
Date:
APPROVED VS PROPOSED SUMMARY TABLE
NF Approved
(D1-D14)
NFC
Proposed
(D1-D9)
NF
Approved
NFC
Proposed
NF
Approved
NFC
Proposed
NF
Approved
NFC
Proposed
NF
Approved
NFC
Proposed
NF
Approved
NFC
Proposed
POND D 9.21 9.18 41.3%38.8%44.51 44.65 1.71 1.64 4949.54 4949.52 0.32 0.34
1. Northfield Approved area and % Impervious taken from Northfield Rational Calcs, dated
October 15, 2019.
2. Northfield Peak Runoff was obtained from the EPA SWMM model output in the "Final
Drainage Report for Northfield" dated February 26, 2020.
3. Northfield Commons Peak Runoff was obtained from the EPA SWM model
in this report.
4. Northfield Commons Spill Depth includes 8 cfs additional flow from Alta Vista Main St.
Northfield Commons
DEVELOPED PEAK RUNOFF
Area (acres)% Impervious
A. Bartel
Highland Development Services
21-1037-00
September 8, 2021
Peak Runoff (cfs)100-yr Detention
Volume (ac-ft)100-yr WSE Spill Depth (ft)
21-1037-00 Rational Calcs (FC).xlsx Page 6 of 7 Highland Development Services
Design Engineer:
Design Firm:
Project Number:
Date:
BASIN SUMMARY TABLE
C2-10 C100
tc
2 yr
(min)
tc
100-yr
(min)
I2
(in/hr)
I100
(in/hr)
Q2
(cfs)
Q100
(cfs)
D1 D1 3.15 48.5%0.61 0.76 10.42 8.73 2.18 8.13 4.19 19.54
D2 D2 0.07 100.0%0.95 1.00 5.00 5.00 2.85 9.95 0.20 0.74
D3 D3 0.07 100.0%0.95 1.00 5.00 5.00 2.85 9.95 0.20 0.74
D4 D4 0.24 17.2%0.38 0.48 7.68 6.90 2.44 8.82 0.22 1.00
D9 D9 2.50 3.9%0.28 0.35 11.42 11.03 2.10 7.42 1.47 6.50
D1-D4&D9 Standard WQ 3.53 30.1%6.28 28.51
D5 D5 0.81 40.7%0.57 0.71 6.05 5.52 2.63 9.43 1.21 5.41
D6 D6 0.16 42.5%0.58 0.73 5.75 5.00 2.67 9.95 0.24 1.13
D7 D7 1.91 69.8%0.76 0.95 10.20 8.54 2.20 8.20 3.18 14.85
D8 D8 0.28 7.6%0.31 0.39 5.69 5.13 2.68 9.62 0.23 1.02
D5-D8 RAIN GARDEN 2.88 55.5%4.86 22.41
D Total 9.18 11.14 50.92
September 8, 2021
DESIGN
POINT
Runoff Coefficient Time of
Concentration Rainfaill Intensity
AREA
(acres)
TRIBUTARY
SUB-BASIN
Peak Runoff
%
IMPERVIOUS
Northfield Commons
DEVELOPED PEAK RUNOFF
A. Bartel
Highland Development Services
21-1037-00
21-1037-00 Rational Calcs (FC).xlsx Page 5 of 7 Highland Development Services
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
40% 0.50
0% 0.25
C2 to C10 C100
D1 137,252 3.151 30,177 29,651 10,694 284 66,446 48.5% 0.61 0.76
D2 3,228 0.074 3,228 0 0 0 0 100.0% 0.95 1.00
D3 3,219 0.074 3,219 0 0 0 0 100.0% 0.95 1.00
D4 10,255 0.235 0 0 1,957 0 8,298 17.2% 0.38 0.48
D5 35,339 0.811 376 13,339 2,168 111 19,345 40.7% 0.57 0.71
D6 6,832 0.157 0 2,669 561 0 3,602 42.5% 0.58 0.73
D7 83,096 1.908 35,591 17,887 7,012 0 22,605 69.8% 0.76 0.95
D8 11,992 0.275 0 0 1,007 0 10,985 7.6% 0.31 0.39
D5+…+D8 137,259 3.151 35,968 33,895 10,748 111 56,538 55.5% 0.66 0.83
D9 108,741 2.496 0 0 4,743 0 103,998 3.9% 0.28 0.35
D1+…+D4+D9 262,694 6.031 36,624 29,651 17,393 284 178,742 30.1% 0.47 0.59
Overall 399,953 9.182 72,592 63,546 28,141 395 235,280 38.8% 0.54 0.67
Northfield Commons
DEVELOPED IMPERVIOUS AREA CALCULATION
DESIGN CRITERIA:
Fort Collins Stormwater Criteria Manual
BASINS:
Highland Development Services
A. Bartel
21-1037-00
September 8, 2021
Land Use
Paved
Roof
Walks
Gravel/Pavers
Lawns
(Heavy, 2-7% Slope)
Sub-basin
Designation
Atotal
(sq feet)
Atotal
(acres)
Weighted %
Impervious
COMPOSITEApaved
(sq feet)
Aroof
(sq feet)
Awalk
(sq feet)
Agravel/pavers
(sq feet)
Alawn
(sq feet)
21-1037-00 Rational Calcs (FC).xlsx Page 1 of 7 Highland Development Services
Design Engineer:
Design Firm:
Project Number:
Date:
City of Fort Collins Stormwater Criteria Manual
Overland Flow Equations for City of Fort Collins Stormwater Criteria Manual
EQUATIONS:
- CoFC Overland Flow
CONSTRAINTS:
300 ft - Overland flow shall not exceed for developed condition
500 ft - Overland flow shall not exceed for undeveloped condition
Final t c = minimum of t i + t t and urbanized basin check
recommended minimum t c = 5 min for urbanized basins
Time of Concentration (2-yr to 10-yr)
D1 D1 48.5% 0.61 3.151 101 0.0485 5.44 480 0.0064 0.10 0.016 1.61 4.98 10.42 581 13.23 10.42
D2 D2 100.0% 0.95 0.074 24 0.0195 1.10 89 0.0177 0.10 0.016 2.67 0.56 5.00 113 10.63 5.00
D3 D3 100.0% 0.95 0.074 24 0.0208 1.08 89 0.0174 0.10 0.016 2.65 0.56 5.00 113 10.63 5.00
D4 D4 17.2% 0.38 0.235 50 0.0418 5.86 155 0.0050 0.10 0.016 1.42 1.82 7.68 205 11.14 7.68
D5 D5 40.7% 0.57 0.811 19 0.1021 2.01 344 0.0050 0.10 0.016 1.42 4.04 6.05 363 12.02 6.05
D6 D6 42.5% 0.58 0.157 40 0.0200 4.87 132 0.0156 0.10 0.016 2.51 0.88 5.75 172 10.96 5.75
D7 D7 69.8% 0.76 1.908 40 0.0248 2.97 722 0.0069 0.10 0.016 1.67 7.23 10.20 762 14.24 10.20
D8 D8 7.6% 0.31 0.275 58 0.0784 5.69 0 0.0050 0.10 0.016 1.42 0.00 5.69 58 10.32 5.69
D9 D9 3.9% 0.28 2.496 38 0.0937 4.46 592 0.0050 0.10 0.016 1.42 6.95 11.42 629 13.50 11.42
September 8, 2021
Northfield Commons
DEVELOPED TIME OF CONCENTRATION
A. Bartel
21-1037-00
Highland Development Services
LENGTH
(ft)
DESIGN CRITERIA:
SUB-BASIN DATA INITIAL/OVERLAND TIME
(ti)TRAVEL TIME (tt)
tc=ti+tt
(min)
Urban Check Final
tc
(min)DESIGN
POINT Sub-basin %
Impervious C2-10
AREA
(acres)
tt
(min)
OVERALL LENGTH
(ft/ft)
tc
(min)
SLOPE
(ft/ft)
ti
(min)
LENGTH
(ft)
SLOPE
(ft/ft)
VELOCITY
(ft/s)
HYDRAULIC
RADIUS
(ft)
ROUGHNESS
COEFFICIENT
ticttt+=
V
Ltt60
=1.871.1
10
180
+=LtcV.R2/3 S 1/2
21-1037-00 Rational Calcs (FC).xlsx Page 2 of 7 Highland Development Services
Design Engineer:
Design Firm:
Project Number:
Date:
City of Fort Collins Stormwater Criteria Manual
Overland Flow Equations for City of Fort Collins Stormwater Criteria Manual
EQUATIONS:
- CoFC Overland Flow
CONSTRAINTS:
300 ft - Overland flow shall not exceed for developed condition
500 ft - Overland flow shall not exceed for undeveloped condition
Final t c = minimum of t i + t t and urbanized basin check
recommended minimum t c = 5 min for urbanized basins
Time of Concentration (100-yr)
D1 D1 48.5% 0.76 3.151 101 0.0485 3.74 480 0.0064 0.10 0.016 1.61 4.98 8.73 581 13.23 8.73
D2 D2 100.0% 1.00 0.074 24 0.0195 0.73 89 0.0177 0.10 0.016 2.67 0.56 5.00 113 10.63 5.00
D3 D3 100.0% 1.00 0.074 24 0.0208 0.72 89 0.0174 0.10 0.016 2.65 0.56 5.00 113 10.63 5.00
D4 D4 17.2% 0.48 0.235 50 0.0418 5.08 155 0.0050 0.10 0.016 1.42 1.82 6.90 205 11.14 6.90
D5 D5 40.7% 0.71 0.811 19 0.1021 1.48 344 0.0050 0.10 0.016 1.42 4.04 5.52 363 12.02 5.52
D6 D6 42.5% 0.73 0.157 40 0.0200 3.51 132 0.0156 0.10 0.016 2.51 0.88 5.00 172 10.96 5.00
D7 D7 69.8% 0.95 1.908 40 0.0248 1.32 722 0.0069 0.10 0.016 1.67 7.23 8.54 762 14.24 8.54
D8 D8 7.6% 0.39 0.275 58 0.0784 5.13 0 0.0050 0.10 0.016 1.42 0.00 5.13 58 10.32 5.13
D9 D9 3.9% 0.35 2.496 38 0.0937 4.08 592 0.0050 0.10 0.016 1.42 6.95 11.03 629 13.50 11.03
September 8, 2021
Northfield Commons
DEVELOPED TIME OF CONCENTRATION
A. Bartel
21-1037-00
Highland Development Services
LENGTH
(ft)
DESIGN CRITERIA:
SUB-BASIN DATA INITIAL/OVERLAND TIME
(ti)TRAVEL TIME (tt)
tc=ti+tt
(min)
Urban Check Final
tc
(min)DESIGN
POINT Sub-basin %
Impervious C2-10
AREA
(acres)
tt
(min)
OVERALL LENGTH
(ft/ft)
tc
(min)
SLOPE
(ft/ft)
ti
(min)
LENGTH
(ft)
SLOPE
(ft/ft)
VELOCITY
(ft/s)
HYDRAULIC
RADIUS
(ft)
ROUGHNESS
COEFFICIENT
ticttt+=
V
Ltt60
=1.871.1
V
Ltt60
=10
180
+=LtcV.R2/3 S 1/2
21-1037-00 Rational Calcs (FC).xlsx Page 3 of 7 Highland Development Services
Design Engineer:
Design Firm:
Project Number:
Date:
EQUATIONS:
Q n = n -yr peak discharge (cfs)
A n = Basin drainage area (ac)
tc (min)Runoff Coeff
(C2-10)C(A) (acres)Intensity
(in/hr)Q (ft3/s)tc (min)Runoff Coeff
(C2-10)C(A) (acres)Intensity
(in/hr)Q (ft3/s)tc (min)Runoff Coeff.
(C100)C(A) (acres)Intensity
(in/hr)Q (ft3/s)
D1 D1 3.151 10.42 0.61 1.92 2.18 4.19 10.42 0.61 1.92 3.72 7.15 8.73 0.76 2.40 8.13 19.54
D2 D2 0.074 5.00 0.95 0.07 2.85 0.20 5.00 0.95 0.07 4.87 0.34 5.00 1.00 0.07 9.95 0.74
D3 D3 0.074 5.00 0.95 0.07 2.85 0.20 5.00 0.95 0.07 4.87 0.34 5.00 1.00 0.07 9.95 0.74
D4 D4 0.235 7.68 0.38 0.09 2.44 0.22 7.68 0.38 0.09 4.16 0.38 6.90 0.48 0.11 8.82 1.00
D5 D5 0.811 6.05 0.57 0.46 2.63 1.21 6.05 0.57 0.46 4.49 2.06 5.52 0.71 0.57 9.43 5.41
D6 D6 0.157 5.75 0.58 0.09 2.67 0.24 5.75 0.58 0.09 4.56 0.42 5.00 0.73 0.11 9.95 1.13
D7 D7 1.908 10.20 0.76 1.45 2.20 3.18 10.20 0.76 1.45 3.75 5.43 8.54 0.95 1.81 8.20 14.85
D8 D8 0.275 5.69 0.31 0.09 2.68 0.23 5.69 0.31 0.09 4.58 0.39 5.13 0.39 0.11 9.62 1.02
D9 D9 2.496 11.42 0.28 0.70 2.10 1.47 11.42 0.28 0.70 3.58 2.51 11.03 0.35 0.88 7.42 6.50
10-yr Peak Runoff 100-yr Peak Runoff
Northfield Commons
DEVELOPED PEAK RUNOFF
City of Fort Collins Stormwater Criteria Manual
DESIGN CRITERIA:
Design
Point Sub-basin Area (acres)
A. Bartel
Highland Development Services
21-1037-00
September 8, 2021
2-yr Peak Runoff
nnnnAICQ=
21-1037-00 Rational Calcs (FC).xlsx Page 4 of 7 Highland Development Services
Appendix D
APPENDIX D – DETENTION POND CALCULATIONS
Is the detention pond being modified?
Could it be clarified these are
comparisons to the approved
Northfield design and no changes are
proposed with this project?
HDS RESPONSE:
"COMPARISON"
ADDED TO TITLE
AND WORDING IN
REPORT CLARIFIED
Pond WQCV
(ac-ft)
Detention
Volume
(1000 cu-ft)
Detention
Volume
(ac-ft)
WQCV+Detention
Volume
(ac-ft)
Volume
Provided
(ac-ft)
100-yr
WSE
(ft)
Max
Depth
(ft)
D 0.09 71.557 1.64 1.73 3.81
4949.52 3.87
NF Commons
Design Engineer:
Design Firm:
Project Number:
Date:
Pond Summary Table
A. Bartel
Highland Development
18-1000-00
September 8, 2021
Pond Summary
21-1037-00 PondCalcs.xls Page 1 of 4 Highland Development Services
NF Commons
Water Quality Pond and Outlet Sizing - Pond D (Outlet Structure D01)
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA:
REQUIRED WATER QUALITY CAPTURE VOLUME (WQCV):
Tributary Area, A 6.031 acres Basins D1-D7 & D14 (not treated by LID)
Composite. Imperviousness, I 30.1%
WQCV (watershed inches)0.152 inches 40-Hour Drain Time (Fig SQ-2)
Required WQCV 0.092 acre-feet Including 20% for Sedimentation
WATER QUALITY OUTLET SIZING (Per USDCM, Volume 3):
Design Water Quality Depth, DWQ 1.26 ft
Determine K40 K40 = 0.013DWQ
2 + 0.22DWQ - 0.10 0.198
Maximum Area per Row, a a = WQCV / K40 0.462 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
A. Bartel
Highland Development Services
18-1000-00
September 8, 2021
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
2.1**
12
AreaWQCVVolume
=
21-1037-00 PondCalcs.xls - WQCV & Outlet Structure - D Page 2 of 4 Interwest Consulting Group
HDS RESPONSE:
CORRECTED
NF Commons
Water Quality Pond and Outlet Sizing - Pond D (Outlet Structure D01)
Design Engineer:
Design Firm:
Project Number:
Date:
A. Bartel
Highland Development Services
18-1000-00
September 8, 2021
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 9 inches
Use USDCM Volume 3, Table 6a-1
Total Width, Wconc 9 inches
Height of Trash Rack Screen, Htr 15 2/16 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)
Circular Perforation Trash Rack Sizing
#156 VEE
3/8in x 1.0in flat bar
Rectangular Perforation Trash Rack Sizing
1 in x 3/16 in
21-1037-00 PondCalcs.xls - WQCV & Outlet Structure - D Page 3 of 4 Interwest Consulting Group
NF Commons
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
REQUIRED WATER QUALITY CAPTURE VOLUME (WQCV):
Tributary Area, A* 6.031 acres
Imperviousness, I 30.1%
WQCV (watershed inches) 0.152 inches 40-Hour Drain Time (Fig SQ-2)
Required WQCV 0.092 acre-feet Including 20% for Sedimentation
Stage Storage
Volume (pond volume calculated using the prismoidal formula):
Pond D
CONTOUR (FT)AREA (FT2)AREA (ACRE)VOLUME
(ACRE-FT)DEPTH (FT)CUMULATIVE VOLUME
(ACRE-FT)
4945.62 0 0.00 0.00
0.00 0.00
4946.00 953 0.02 0.00
0.38 0.00
4946.50 4839 0.11 0.03
0.88 0.03
4947.00 8716 0.20 0.08
1.38 0.11
4947.50 10860 0.25 0.11
1.88 0.22
4948.00 19723 0.45 0.17
2.38 0.40
4948.50 29964 0.69 0.28
2.88 0.68
4949.00 42821 0.98 0.42
3.38 1.09
4949.50 52864 1.21 0.55
3.88 1.64
4950.00 59809 1.37 0.65
4.38 2.29
4950.50 65735 1.51 0.72
4.88 3.01
4951.00 74113 1.70 0.80 5.38 3.81
0.09 Acre-Ft Interpolates to an Elev. of 4946.88 ft
100-yr Water Surface Elevation (per SWMM) =4949.52 ft, max depth = 3.87 ft
*sub-basins D1-D4 & D9 (those not treated by rain garden)
Required Water Quality Capture Volume =
Critical Pond Elevations - D Basin
A. Bartel
Highland Development
18-1000-00
September 8, 2021
Fort Collins Amendments to the Urban Drainage and Flood Control District Criteria Manual
()
3
2121 DepthAAAA
V
++=
2.1**
12
AreaWQCVVolume
=
21-1037-00 PondCalcs.xls Page 4 of 4 Highland Development Services
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Sep 2 2021
D1 Spill
User-defined
Invert Elev (ft) = 51.43
Slope (%) = 0.50
N-Value = 0.013
Calculations
Compute by: Known Q
Known Q (cfs) = 52.65
(Sta, El, n)-(Sta, El, n)...
( 0.00, 52.04)-(17.00, 51.99, 0.013)-(44.00, 51.84, 0.013)-(126.00, 51.43, 0.013)-(184.00, 51.76, 0.013)-(219.00, 53.12, 0.013)
Highlighted
Depth (ft) = 0.34
Q (cfs) = 52.65
Area (sqft) = 21.71
Velocity (ft/s) = 2.42
Wetted Perim (ft) = 126.26
Crit Depth, Yc (ft) = 0.35
Top Width (ft) = 126.26
EGL (ft) = 0.43
-50 0 50 100 150 200 250 300
Elev (ft)Depth (ft)Section
50.50 -0.93
51.00 -0.43
51.50 0.07
52.00 0.57
52.50 1.07
53.00 1.57
53.50 2.07
54.00 2.57
Sta (ft)
Pond D Peak Flow + Alta Vista Main
St = 44.65 cfs + 8 cfs = 52.65 cfs
Are basins included for this somewhere?
Mention of these flows pops up in a few
spots but they don't seem to be addressed
in detail.
Can you please provide some clarification
on what is being included in this report for
these Alta Vista flows? They're not exactly
part of this project and more context is
needed to help explain what is currently
shown.
HDS RESPONSE:
INFORMATION ON THE 8 CFS
FLOW FROM ALTA VISTA
WAS PROVIDED TO US BY
THE CITY OF FORT COLLINS
AND IS NOT INCLUDED IN
OUR MODEL PER DIRECTION
FROM THE CITY
Appendix E
APPENDIX E – INLET CALCULATIONS
NF Commons
TYPE 13 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:
Width (W ): 1.875 ft
Length (L ): 3.27 ft
Opening Ratio (R ): 0.375 sqft/sqft
Reduction Factor (F ): 50%
Single Grate Open Area (A ): 2.30 sqft
Allowed Head (H ): 0.5 ft
Number of Grates
Inlet
Capacity (cfs)
Inlet Capacity
w/ Reduction
Factor (cfs)
1 Single 8.74 4.37
2 Double 17.48 8.74
3 Triple 26.22 13.11
4 Quad 34.97 17.48
5 Penta 43.71 21.85
INLET SIZING CALCULATIONS
Inlet ID:
Design
Flow Rate
(Q 100 , cfs):
Allowed Head
(H , ft):
Single Grate
Capacity
(Q sg , cfs):
Number of
Grates:
Inlet
Capacity
(Qg, cfs)
Inlet-D01 (DP D1)19.54 0.5 4.37 Penta Type 13 TRUE
Apply Reduction Factor for the Allowable Capacity.
Assumed Capacity w/ 0.5' Head Allowed
A. Bartel
Highland Development Services
21-1037-00
September 8, 2021
1
CA 2
Page1
NF Commons
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/s 2)
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)
Inlet-D05 (DP D4)1.00 0.5 11.12
Width (W ):
A. Bartel
Highland Development Services
21-1037-00
September 8, 2021
Apply Reduction Factor for the Allowable Capacity.
Assumed Capacity per Head Allowed
Inlet Grate Open Area (A ):
Reduction Factor (F ):
Opening Ratio (R ):
Length (L ):
𝑄𝐺=𝑄𝑖(1 −𝐹)
𝑄𝑖=CA 2𝑔𝐻
Page2
Appendix F
APPENDIX F – LOW IMPACT DEVELOPMENT CALCULATIONS
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
Low Impact Development Summary
Sq-Ft Acres
Impervious Area
(sq-ft)
% of Impervious
Area Requiring
Treatment
Impervious Area
Requiring
Treatment
537,816 12.35 330,931 50% 165,465
1,189,400 27.30 794,336 75% 595,752
40,986 0.94 20,720 75% 15,540
304,148 6.98 248,720 0% N/A
445,251 10.22 0 0% N/A
2,517,600 57.80 1,394,707 - 776,757
LID
Facility
Contributing
Basins
Area Drainage
to LID
(sq-ft)
% Impervious
Impervious
Area Treated
(sq-ft)
WQCV12-hr
(watershed inches)
WQCV12-hr
(cu-ft)
Treatment
Method
A2 A1+…+A12 427,599 66.5% 302,122 0.21 7,414 Infiltration Gallery
B1 B13+…B17 110,074 79.3% 93,219 0.26 2,378 Rain Garden
B2 B10+…+B12 146,450 55.7% 86,485 0.18 2,173 Infiltration Gallery
B3 B1+…+B9 426,521 54.7% 251,577 0.18 6,243 Infiltration Gallery
D1 D5+...+D8 137,259 55.5% 80,721 0.18 2,031 Rain Garden
EDB Pond Contributing
Basins
Drainage Area
(sq-ft)
Drainage Area
(sq-ft)% Impervious WQCV40-hr
(watershed inches)
WQCV40-hr
(ac-ft)
Pond A A18 131,657 3.022 12.5% 0.08 0.024
Pond B B18+…+B20 165,673 3.803 22.5% 0.13 0.048
Pond C C1+…+C5 160,137 3.676 38.2% 0.18 0.064
Pond D D1+…+D4+D9 262,694 6.031 30.1% 0.15 0.092
776,757
814,124
104.8%
Area (sq-ft) Area (acres) Treatment Ratio
1,247,903 28.65 49.6%
720,162 16.53 28.6%
323,951 7.44 12.9%
126,940 2.91 5.0%
2,418,956 55.53 96.1%
98,790 2.27 3.9%
2,517,746 57.80
NF Commons
Low Impact Development
Total % Treatment
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 Treated (sq-ft)
Total Impervious Area Required for LID Treatment (sq-ft)
LID Treatment Summary
LID Treatment Areas
Detention / Landscape Areas (no LID treatment)
A. Bartel
Highland Development Services
21-1037-00
September 8, 2021
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
Totals
Standard Water Quality Areas
Total Area Treated by LID
Total Area Treated by EDB
Total Area Treated by Snout (Suniga)
Description
Single Family Area
Multifamily Area
Commercial Area
Suniga Road (no LID treatment)
Total Area unable to be Treated
(Basins A13, A14, portion of A16, & A17)
Total Treated Area
Total Improvement Area
Water Quality Area Treatment Summary
Description
Total Area Treated by Snout (Lemay - Basins A15 & D15)
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =55.5 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.555
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.18 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 137,259 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 =2,031 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 =1524 sq ft
D) Actual Flat Surface Area AActual =2071 sq ft
E) Area at Design Depth (Top Surface Area)ATop =2846 sq ft
F) Rain Garden Total Volume VT=2,459 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
HDS
September 1, 2021
NF Commons (Mercy)
LID Facility D1 - Rain Garden
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
21-1037-00 UD-BMP_v3.07_Pond D.xlsm, RG 9/1/2021, 8:52 AM
1995 on page 8?
Similar to pond,
could it be clarified
these calcs are for
comparison
purposes only and
the approved RG
design is not
changing?
HDS RESPONSE:
CORRECTED
HDS RESPONSE: THIS IS
NOT A COMPARISON,
RATHER THE ACTUAL AREA
& % IMPERVIOUS BEING
DIRECTED TO THE RG AND
THIS CONFIRMS THAT THE
PREVIOUS RG DESIGN IS
MORE THAN ADEQUATE
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:Rain garden is proposed to be irrigated. No sprinkler heads on flat surface.
Design Procedure Form: Rain Garden (RG)
J.Claeys
HDS
September 1, 2021
NF Commons (Mercy)
LID Facility D1 - Rain Garden
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
21-1037-00 UD-BMP_v3.07_Pond D.xlsm, RG 9/1/2021, 8:52 AM