HomeMy WebLinkAboutBLOCK 23 MORNINGSTAR - FDP200027 - SUBMITTAL DOCUMENTS - ROUND 4 - DRAINAGE REPORT
Final Drainage Report
Morningstar/Block 23
Fort Collins, Colorado
March 17, 2021
Prepared for:
Hazeldon/Morningstar Fort Collins, LLC
300 North Mason Street
Fort Collins, Colorado 80524
Prepared by:
301 N. Howes Street Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158
www.northernengineering.com
Project Number: 1024-004
This Drainage Report is consciously provided as a PDF. Please consider
the environment before printing this document in its entirety. When a hard
copy is necessary, we recommend double-sided printing.
March 17, 2021
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: Final Drainage Report for
Morningstar/Block 23
Dear Staff:
Northern Engineering is pleased to submit this Final Drainage Report for your review.
This report accompanies the combined Final Plan submittal for the proposed
Morningstar/Block 23.
This report has been prepared in accordance with the Fort Collins Stormwater Criteria
Manual (FCSCM) and serves to document the stormwater impacts associated with the
proposed Morningstar/Block 23 project. We understand that review by the City of Fort
Collins is to assure general compliance with standardized criteria contained in the
FCSCM.
If you should have any questions as you review this report, please feel free to contact
us.
Sincerely,
Northern Engineering Services, Inc.
Frederick S. Wegert, PE
Project Engineer
Final Drainage Report March 17, 2021
Morningstar/Block 23 Table of Contents
Table of Contents
I. General Location and Description ........................................................................ 1
II. Drainage Basins and Sub-Basins .......................................................................... 4
III. Drainage Design Criteria ..................................................................................... 5
IV. Conclusions ....................................................................................................... 16
V. References ......................................................................................................... 18
Tables and Figures
Figure 1: Vicinity Map ...................................................................................... 1
Figure 2: Aerial Photograph ............................................................................ 2
Figure 3: City Floodplains................................................................................ 4
Table 1: Number of Chambers ........................................................................ 9
Table 2: East On-Site Drainage Characteristics ............................................ 14
Table 3: West On-Site Drainage Characteristics ........................................... 14
Table 4: Required Detention & Water Quality Volumes ................................ 15
Table 5: Designed Detention & Water Quality Volumes ................................ 15
Appendices
Appendix A – Hydrologic Computations
Appendix B – Hydraulic Computations
Appendix C – Water Quality/LID Design Computations
Appendix D – Erosion Control Report
Appendix E – USDA Soils Report
Appendix F – FEMA Firmette
Map Pocket
DR1 – Drainage Exhibit
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 1 of 20
I. General Location and Description
A. Location
1. Vicinity Map
2. The Morningstar/Block 23 project site is located in the northeast quarter of
Section 11, Township 7 North, Range 69 West of the 6th Principal Meridian, City
of Fort Collins, County of Larimer, State of Colorado.
3. The project site (refer to Figure 1) is bordered to the north by Cherry Street; to the
south by Maple Street; to the east by College Avenue; to the west by the Old
Town Flats subdivision; and to the northwest by the Burlington Northern
Railroad and the intersection of Cherry and Mason Streets.
Figure 1: Vicinity Map
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 2 of 20
4. There is a 15” storm sewer, providing a drainage outlet for Old Town Flats,
bisecting the eastern half of the project site.
B. Description of Property
1. The Morningstar/Block 23 project site is comprised of ±2.62 acres.
2. A north-south public alley bisects the property into an eastern parcel and a
western parcel. The east half of the site is currently occupied by four abandoned
commercial buildings as well as various concrete and gravel parking areas. The
west half of the site is currently an undeveloped gravel lot. A portion of the
gravel lot is used to stockpile material by Burlington Northern Railroad during
maintenance activities for the railroad tracks.
1. The existing groundcover consists of weed-infested concrete and gravel parking
lots with limited landscaping in the northeast corner. The project site generally
drains from west to east across flat grades (e.g., <2.00%).
2. The west half, the alley, and portions of the east half of the existing runoff drains
radially inward towards an existing storm inlet located onsite. The outer ring of
the project site generally drains into the surrounding curb and gutter for Cherry
Street, Maple Street, and College Avenue. The entire site, both the existing storm
inlet and the surrounding streets, drain towards an existing Type-R inlet located
Figure 2: Aerial Photograph
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 3 of 20
within College Avenue in the northeast corner of the project. Ultimately, the
Type-R inlet drains, via the Fort Collins storm sewer system, into the Cache La
Poudre River ±1,160 feet to the north.
3. According to the United States Department of Agriculture (USDA) Natural
Resources Conservation Service (NRCS) Soil Survey website:
(http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx),
the site consists primarily of Paoli fine sandy loam (Hydrologic Soil Group A).
4. There is a 15” storm sewer, providing a drainage outlet for Old Town Flats,
bisecting the eastern half of the project site. Old Town Flats, towards the
southwest of the project, is the only significant off-site source of stormwater that
impacts the project. The 15” outfall for Old Tow Flats discharges into a Type-R
inlet in College Avenue located at the northeast corner of the project site, and it
ultimately drains towards the Cache La Poudre River ±1,160 feet to the north.
5. The proposed development will consist of long-term care facility, commercial
units, and a parking structure. The mixed-use building, consisting of long-term
facility and commercial units, will be located east of the alley. The parking
structure will be located west of the alley. Other proposed improvements
include: a new asphalt within the alley, landscaping planters, new sidewalks
within the surrounding streets, and storm sewer improvements in the alley,
Cherry Street, and Maple Street.
6. The proposed land use is mixed-use. This is a permitted use in the Downtown
District (D).
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 4 of 20
C. Floodplain
1. The subject property is not located in a FEMA or City regulatory floodplain. In
particular, the project site is not located within a FEMA designated 100-year
floodplain per Map Number 08069C0979H (Effective date: May 2, 2012).
II. Drainage Basins and Sub-Basins
A. Major Basin Description
Morningstar/Block 23 is located within the City of Fort Collins Old Town major
drainage basin. Specifically, the project site is situated in the north-central portion of
this major drainage basin. This basin is in north-central Fort Collins, and it has a
drainage area of approximately 2,120 acres, including approximately 400 acres of the
Colorado State University Campus. The Old Town major drainage basin generally
drains from west to east. It receives some runoff from the Canal Importation basin
directly west of Old Town. Most of the runoff form the Old Town major drainage
basin drains into the Poudre River.
B. Sub-Basin Description
1. The outfall for the project site is an existing Type-R inlet located in the northeast
corner of the site within College Avenue.
Figure 3: City Floodplains
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Morningstar/Block 23 Page 5 of 20
2. The existing site can be defined with fourteen (14) Sub-Basins that encompasses
the entire project site.
3. The existing site runoff generally drains from west to east into an existing Type-R
inlet in College Avenue.
4. Old Town Flats, towards the southwest of the project, is the only significant off-
site source of stormwater that impacts the project. The outfall for Old Town Flats
bisects the eastern half of Morningstar/Block 23 in a 15” storm sewer discharging
into a Type-R inlet in College Avenue located at the northeast corner of the
project site.
The developer will construct a new storm sewer to convey drainage from
Morningstar/Block 23 and Old Town Flats along the alley, Cherry Street, and
discharging into an existing single combination inlet at the intersection of Cherry
Street and College Avenue. The combination inlet in Cherry Street will need to
be reconstructed to accommodate the proposed pipe and site improvements.
Drainage will then travel in the City’s storm sewer system to the historic outfall
(the Type-R inlet in College Avenue) for Morningstar/Block 23 and Old Town
Flats.
5. The onsite imperviousness, with tabulated historic versus proposed impervious
areas, is documented within Appendix A.
III. Drainage Design Criteria
A. Optional Provisions
There are no optional provisions outside of the FCSCM proposed with Morningstar/
Block 23.
B. Stormwater Management Strategy
The overall stormwater management strategy employed with Morningstar/Block 23
utilizes the “Four Step Process” to minimize adverse impacts of urbanization on
receiving waters. The following is a description of how the proposed development
has incorporated each step.
Step 1 – Employ Runoff Reduction Practices. The first consideration taken in trying
to reduce the stormwater impacts of this development is the site selection itself. By
choosing an already developed site with public storm sewer currently in place, the
burden is significantly less than developing a vacant parcel absent of any
infrastructure.
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 6 of 20
The Morningstar/Block 23 aims to reduce runoff peaks, volumes and pollutant loads
from frequently occurring storm events (i.e., water quality (i.e., 80th percentile) and
2-year storm events) by implementing Low Impact Development (LID) strategies.
Wherever practical, runoff will be routed across landscaped areas, within rain
gardens, or through an infiltration gallery. These LID practices reduce the overall
amount of impervious area, while at the same time Minimizing Directly Connected
Impervious Areas (MDCIA). The combined LID/MDCIA techniques will be
implemented, where practical, throughout the development, thereby slowing runoff
and increasing opportunities for infiltration.
Step 2 – Implement BMPs that Provide a Water Quality Capture Volume (WQCV)
with Slow Release. The efforts taken in Step 1 will help to minimize excess runoff
from frequently occurring storm events; however, urban development of this
intensity will still have stormwater runoff leaving the site. The primary water quality
treatment will occur in the underground vaults located along the alley. The
underground vaults are located on private property per City of Fort Collins
regulations.
Step 3 – Stabilize Drainageways. While this step may not seem applicable to
Morningstar/Block 23, the proposed project indirectly helps achieve stabilized
drainageways, nonetheless. Once again, site selection has a positive effect on stream
stabilization. By developing an infill site with existing stormwater infrastructure,
combined with LID and MDCIA strategies, the likelihood of bed and bank erosion is
reduced. Furthermore, this project will pay one-time stormwater development fees,
as well as ongoing monthly stormwater utility fees, both of which help achieve
Citywide drainageway stability.
Step 4 – Implement Site Specific and Other Source Control BMPs. This step
typically applies to industrial and commercial developments.
C. Development Criteria Reference and Constraints
1. The subject property is not part of any Overall Development Plan (ODP)
drainage study or similar “development/project” drainage master plan.
2. The site plan is constrained on all sides by either a public street, a railroad, or
existing development. The northeast corner of the project site is the intersection
of College Avenue and Cherry Street. This intersection includes a level railway
junction between the Burlington Northern Railroad, Great Western Railroad, and
US Highway 287. The southeast corner of the project is the junction of US
Highway 287 and Colorado State Highway 14.
3. The existing inlets in College Avenue (a combination and a Type-R inlet) will
function as the ultimate outfall for the project site.
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Morningstar/Block 23 Page 7 of 20
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as
depicted in Figure 3.4-1 of the FCSCM, serve as the source for all hydrologic
computations associated with Morningstar/Block 23 development. Tabulated
data contained in Table 3.4-1 has been utilized for Rational Method runoff
calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables 3.2.1 and 3.2.2 of the FCSCM.
3. The Rational Formula-based Federal Aviation Administration (FAA) procedure
was utilized for detention storage calculations.
4. Two separate design storms have been utilized to address distinct drainage
scenarios. The first event analyzed is the “Minor,” or “Initial” Storm, which has a
2-year recurrence interval. The second event considered is the “Major Storm,”
which has a 100-year recurrence interval.
E. Hydraulic Criteria
1. The drainage facilities proposed with Morningstar/Block 23 project are designed
in accordance with criteria outlined in the FCSCM and/or the Urban Drainage
and Flood Control District’s Urban Storm Drainage Criteria Manual. Urban
Drainage Flood Control District recently changed their name to Mile High Flood
District (MHFD).
2. As stated in Section I.C.1, above, the subject property is not located within a
FEMA or City floodplain limits.
F. Floodplain Regulations Compliance
1. The project is located outside of a FEMA or City floodplain, and as such, it will
not be subject to any floodplain regulations.
2. Despite the project not being located within the floodplain, consideration has
been given to the floodplain elevations as they relate to the proposed buildings
and the finished floors have been elevated accordingly.
G. Modifications of Criteria
No formal modifications are requested at this time.
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 8 of 20
H. Conformance with Water Quality Treatment Criteria
City Code requires that 100% of runoff from a project site receive some sort of water
quality treatment. This project proposes to provide water quality treatment through
the use of an underground infiltration gallery (aka – underground chambers) located
midway on the east side of the alley, a sand filter and detention vault within the
parking structure, and planter boxes constructed to provide the City of Fort Collins
biomedia soil section. The chambers, sand filter vault, and biomedia planter boxes
are considered a LID treatment method. Due to the physical constraints associated
with an infill project of this nature and the prohibition of providing water quality
facilities within the public right-of-way, there are some small, narrow areas around
the perimeter of the project that cannot be captured. The uncaptured areas tend to be
narrow strips of concrete flatwork that link the building entrances to the public
sidewalks and small planter beds between the building and public sidewalks or
property lines.
I. Conformance with Low Impact Development (LID)
The project site will conform with the requirement to treat a minimum of 75% of the
project site using a LID technique. Please see Appendix C for LID design
information, table, and exhibit(s). As shown in the LID table provided in the
appendix, 89.0% of the proposed site impervious area will receive LID treatment,
which exceeds the minimum required.
J. Sizing of LID Facilities
Infiltration Gallery & Planter Boxes
1. The infiltration gallery was sized by first determining the required water quality
capture volume (WQCV) for Basins E1 - E5. A 12-hour drain time was used in
this calculation.
2. The WQCV for the infiltration gallery was then reduced by the available volume
in the planter boxes. The WQCV was calculated to be 2,035 cubic feet for the east
side improvements. Per FCSM requirements for rain gardens, the planter boxes
will be capable of treating a WQCV of 690 cubic feet to a depth of 1 foot.
Therefore, the minimum required WQCV within the infiltration gallery is 1,345
cubic feet (2,035 ft3 – 690 ft3 = 1,345 ft3).
3. Once the WQCV was identified, the minimum number of vaults needed to
achieve the minimum WQCV was calculated. This volume includes the adjacent
aggregates
4. The total release rate for the underground vaults wrapped in geofabric, with the
potential to constrict flows and resulting in sedimentation, was calculated to be
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 9 of 20
0.42 cfs. This rate was determined by multiplying the vault bottom square
footage x 0.35 gpm.
5. After completing the volume calculated utilizing the WQ flow rate into the
chamber and the calculated release rate through the fabric, the number of
chambers was increased as needed to confirm the resulting WQCV is provided
within the empty volume of the underground chambers. This is intended to
ensure the chambers do not become overwhelmed in the water quality storm
event before “discharging” flows into the surrounding aggregates.
6. Finally, additional chambers, without fabric, were added to provide the required
detention volume for the east side of the project.
Number of Chambers
Type of
Chamber
# of
Chambers
Volume
(ft3)
Infiltrator Row SC-740 17 1,273
Detention SC-740 13 974
Total 30 2,247
Required Chamber Volume 2,067
Table 1: Number of Chambers
Sand Filter Vault
1. The sand filter vault was sized by first determining the required water quality
capture volume (WQCV) for the parking garage footprint (Basin W2) assuming
100% imperviousness. A 12-hour drain time was used in this calculation.
K. General Concept
1. The main objective of Morningstar/Block 23 drainage design is to maintain
existing drainage patterns, while not adversely impacting adjacent properties.
2. The outfall for Old Town Flats passes through the project site. This outfall will
be re-routed, along with stormwater from Morningstar/Block 23, into a new
storm sewer within the alley and Cherry Street, and it will discharge into an
existing single combination inlet at the intersection of Cherry Street and College
Avenue. Drainage will then travel in the City’s storm sewer system to the
historic outfall (the Type-R inlet in College Avenue) for Morningstar/Block 23
and Old Town Flats. The combination inlet at the intersection of Cherry Street
and College Avenue, and the existing storm sewer, will be replaced to
accommodate the increased flows.
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 10 of 20
3. A list of tables and figures used within this report can be found in the Table of
Contents at the front of the document. The tables and figures are located within
the sections to which the content best applies.
4. Drainage for the project site has been analyzed using fourteen (16) drainage Sub-
Basins, designated as Sub-Basins A1, A2, A3, B1, B2, C1, C2, E1 – E5, and W1 –
W4. The drainage patterns anticipated for the basins are further described below.
Sub-Basin A1
Sub-Basin A1 consists the right-of-way improvements along Cherry Street and at
the intersection of Cherry Street and College Avenue. This sub-basin is
comprised primarily of concrete flatwork and limited landscaped areas. The sub-
basin will drain into the curb and gutter along Cherry Street and be captured by
existing inlets at the intersection of Cherry Street and College Avenue. Flows will
then proceed to Cache La Poudre River via Fort Collins storm sewer system.
This basin is contained entirely within the Cherry Street and College Avenue
rights-of-way.
Sub-Basin A2
Sub-Basin A2 consists the right-of-way improvements along College Avenue.
This sub-basin is comprised primarily of concrete flatwork and limited
landscaped areas. The sub-basin will drain into the curb and gutter along College
Avenue and be captured by existing inlets at the intersection of Maple Street and
College Avenue. Flows will then proceed to Cache La Poudre River via Fort
Collins storm sewer system. This basin is contained entirely within the College
Avenue right-of-way.
Sub-Basin A3
Sub-Basin A3 consists the right-of-way improvements along Maple Street. This
sub-basin is comprised primarily of concrete flatwork and limited landscaped
areas. The sub-basin will drain into the curb and gutter along Maple Street and
be captured by a proposed inlet at the intersection of Maple Street and College
Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins
storm sewer system. This basin is contained entirely within the College Avenue
right-of-way.
Sub-Basin B1
Sub-Basin B1 consists the right-of-way improvements along Cherry Street north
of the parking garage and the north entrance to the alley. This sub-basin is
comprised primarily of concrete flatwork and limited landscaped areas. The
sub-basin will drain into the curb and gutter along Cherry Street. Flows will be
captured by the existing inlets at intersection of Cherry Street and College
Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 11 of 20
storm sewer system. This basin is contained entirely within the College Avenue
right-of-way.
Sub-Basin B2
Sub-Basin B2 consists of the alley. This sub-basin is comprised primarily of
asphalt roadway and concrete sidewalks. Flows from the sub-basin will flow
north to be captured by a proposed inlet midway along the east side of the alley.
It will then be conveyed into the nearby underground chambers. The flows will
then be directed within storm sewer pipes to the existing inlets at the intersection
of Cherry Street and College Avenue. Flows will then proceed to Cache La
Poudre River via Fort Collins storm sewer system.
Sub-Basin C1
Sub-Basin C1 consists of the north courtyard. This sub-basin is comprised
primarily of concrete sidewalks. Flows from the sub-basin will flow towards the
underground chambers in Sub-Basin E4 via plumbing through the building. It
will then be conveyed into the nearby underground chambers. The flows will
then be directed via storm sewer to the intersection of Cherry Street and College
Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins
storm sewer system.
Sub-Basin C2
Sub-Basin C2 consists of the north courtyard. This sub-basin is comprised
primarily of concrete sidewalks. Flows from the sub-basin will flow towards the
underground chambers in Sub-Basin E4 via plumbing through the building. It
will then be conveyed into the nearby underground chambers. The flows will
then be directed via storm sewer to the intersection of Cherry Street and College
Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins
storm sewer system.
Sub-Basin E1
Sub-Basin E1 consists of the northeast corner of the project site. This sub-basin is
comprised primarily of roof area and adjacent sidewalk within the project
boundary. Some minor flows from the sidewalk will drain into Sub-Basin A1.
Larger flows will be conveyed via roof downspouts and the building storm
sewer system to a landscaping planters and underground chambers located
midway on the east side of the alley. Major flows will then be directed within
storm sewer pipes to the existing inlets at the intersection of Cherry Street and
College Avenue. Flows will then proceed to Cache La Poudre River via Fort
Collins storm sewer system. This basin is contained entirely within the project
boundaries.
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Morningstar/Block 23 Page 12 of 20
Sub-Basin E2
Sub-Basin E2 consists of the eastern area of the east building. This sub-basin is
comprised primarily of roof area and adjacent sidewalk within the project
boundary. Some minor flows from the sidewalk will drain into Sub-Basin A2.
Larger flows will be conveyed via roof downspouts and the building storm
sewer system to a landscaping planters and underground chambers located
midway on the east side of the alley. Major flows will then be directed within
storm sewer pipes to the existing inlets at the intersection of Cherry Street and
College Avenue. Flows will then proceed to Cache La Poudre River via Fort
Collins storm sewer system. This basin is contained entirely within the project
boundaries.
Sub-Basin E3
Sub-Basin E3 consists of the southern area of the east building. This sub-basin is
comprised primarily of roof area and adjacent sidewalk within the project
boundary. Some minor flows from the sidewalk will drain into Sub-Basin A3.
Larger flows will be conveyed via roof downspouts and the building storm
sewer system to a landscaping planters and underground chambers located
midway on the east side of the alley. Major flows will then be directed within
storm sewer pipes to the existing inlets at the intersection of Cherry Street and
College Avenue. Flows will then proceed to Cache La Poudre River via Fort
Collins storm sewer system. This basin is contained entirely within the project
boundaries.
Sub-Basin E4
Sub-Basin E4 consists of the western area of the east building. This sub-basin is
comprised primarily of roof area and adjacent sidewalk within the project
boundary. Some minor flows from the sidewalk will drain into Sub-Basin B2.
Larger flows will be conveyed via roof downspouts and the building storm
sewer system to a landscaping planters and underground chambers located
midway on the east side of the alley. Major flows will then be directed within
storm sewer pipes to the existing inlets at the intersection of Cherry Street and
College Avenue. Flows will then proceed to Cache La Poudre River via Fort
Collins storm sewer system. This basin is contained entirely within the project
boundaries.
Sub-Basin E5
Sub-Basin E5 consists of the northwest corner of the east parcel. This sub-basin is
comprised primarily of concrete flatwork and limited landscaping within the
project boundary. The sub-basin will drain into the curb and gutter along Cherry
Street via Sub-Basin B1. Flows will be captured by the existing inlets at
intersection of Cherry Street and College Avenue. Flows will then proceed to
Cache La Poudre River via Fort Collins storm sewer system. This basin in
contained entirely within the College Avenue right-of-way.
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Morningstar/Block 23 Page 13 of 20
Sub-Basin OS1
Sub-Basin OS1 consists of Cherry Street between the Union Pacific Railroad
tracks and Great Western Railway. This sub-basin is comprised primarily of
concrete flatwork and asphalt. The sub-basin will drain into the curb and gutter
along the north side of Cherry Street. Flows will be captured by the existing
inlets at intersection of Cherry Street and College Avenue. Flows will then
proceed to Cache La Poudre River via Fort Collins storm sewer system. This
basin in contained entirely within the College Avenue right-of-way. Sub-Basin
OS1 is provided to assist in sizing Storm Sewer A.
Sub-Basin W1
Sub-Basin W1 consists of the landscaping and sidewalk northeast of the parking
garage. This sub-basin is comprised primarily of concrete flatwork and limited
landscaped areas. The sub-basin will drain into the curb and gutter along Cherry
Street via Sub-Basin B1. Flows will be captured by the existing inlets at
intersection of Cherry Street and College Avenue. Flows will then proceed to
Cache La Poudre River via Fort Collins storm sewer system. This basin in
contained entirely within the College Avenue right-of-way.
Sub-Basin W2
Sub-Basin W2 consists of the parking garage. This sub-basin is comprised
primarily of roof area and adjacent sidewalk within the project boundary. Some
minor flows from the sidewalk will drain into Sub-Basin B2. Drainage will be
conveyed via roof downspouts and the building storm sewer system to a sand
filter and detention vault located on the west side of the parking garage (Basin
W4). Drainage will then be directed within storm sewer pipes to the proposed
storm sewer in the alley. The storm sewer will convey drainage north to Cherry
Street, along Cherry Street, and to the existing inlets at the intersection of Cherry
Street and College Avenue. Flows will then proceed to the Cache La Poudre
River via Fort Collins storm sewer system.
Sub-Basin W3
Sub-Basin W3 consists of landscaping and asphalt south and east of the parking
garage. This Sub-Basin is comprised primarily of landscaping and asphalt within
the project boundary. Flows will be conveyed surface drainage to the alley (Sub-
Basin B1), and it will be collected by the storm sewer system in Sub-Basin B2. The
storm sewer will convey drainage north to Cherry Street, along Cherry Street,
and to the existing inlets at the intersection of Cherry Street and College Avenue.
Flows will then proceed to the Cache La Poudre River via Fort Collins storm
sewer system.
Sub-Basin W4
Sub-Basin W4 consist of landscaped areas along the west edge of the parking
garage. This Sub-Basin is comprised primarily of landscaping, a sand filter vault,
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 14 of 20
and a detention vault for Sub-Basins W1, W3, and W4. Flows from the sand and
detention vault will be directed, via the building’s storm sewer system, through
the parking garage and towards the storm system in the alley. Flows will then
proceed to Cache La Poudre River via Fort Collins storm sewer system. Some
minor flows from the Sub-Basin will follow historic drainage patterns into the
Burlington Northern Railroad; thence into the existing curb and gutter along
Cherry Street; and finally captured by the existing inlets at the intersection of
Cherry Street and College Avenue.
All drainage basins maintain their historic outfall at the intersection of Cherry
Street and College Avenue. A full-size copy of the Drainage Exhibit can be
found in the Map Pocket at the end of this report.
East On-Site Drainage Characteristics
Existing Proposed
Basin Area (ft2) 76,011 76,011
Impervious Area (ft2) 66,085 74,443
Percent Impervious 84% 90%
2-Year Flowrate (cfs) 3.57 2.32
10-Year Flowrate (cfs) 6.10 7.90
100-Year Flowrate (cfs) 14.62 17.40
Table 2: East On-Site Drainage Characteristics
West On-Site Drainage Characteristics
Existing Proposed
Basin Area (ft2) 38,085 38,085
Impervious Area (ft2) 15,234 26,662
Percent Impervious 40% 76%
2-Year Flowrate (cfs) 0.79 0.86
10-Year Flowrate (cfs) 1.34 2.90
100-Year Flowrate (cfs) 3.42 7.30
Table 3: West On-Site Drainage Characteristics
L. Specific Details
1. The developer will construct two onsite detention facilities for the project. An
underground chamber system and planters will be used to provide the required
detention storage, water quality, and LID treatment for the east half of the site.
The planters will utilize the City of Fort Collins biomedia specifications for a rain
garden to provide LID and water quality treatment. An isolator row, an
underground chamber row wrapped in filter fabric, will provide additional
water quality and LID treatment. The remaining underground chambers will
provide the required detention volume.
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 15 of 20
A chamber detention system will provide 1,348 ft3 of water quality treatment and
8299 ft3 of detention with a release rate of 14.64 cfs. The rain gardens will
provide an additional 690 ft3 of water quality treatment. This results in a total of
2,937 ft3 of water quality and detention for the east half of the site. The required
detention and water quality volume is 2,852 ft3. See sections IV.B.3 and IV.B.4,
below, for further discussion on the release rate used to determine the required
detention volumes.
2. A sand filter and detention vault system, located west of the parking garage, will
provide the water quality and detention storage for the west half of the site. It
will provide 1,215 ft3 of water quality treatment and 2,037 ft3 of detention with a
release rate of 3.39 cfs. This results in a total of 3,252 ft3 of water quality and
detention for the west half of the site. The required detention and water volume
is 2,450 ft3. See sections IV.B.3 and IV.B.4, below, for further discussion on the
release rate used to determine the required detention volumes.
Required Detention and Water Quality Volumes
Release
Rate
(cfs)
Required
Detention
Volume (ft3)
Required
Water
Quality
Volume (ft3)
East Parcel 14.64 817 2,035
West Parcel 3.42 1,384 1,066
Table 4: Required Detention & Water Quality Volumes
Designed Detention and Water Quality Volumes
Design
Detention
Volume
(ft3)
Design
Water
Quality
Volume (ft3)
East Rain Gardens 0 690
East Stormtech Chambers 899 1,348
Total East Side 899 2,038
West Detention Vault 2,037 0
West Sand Filter Vault 0 1,215
Total West Side 2,037 1,215
Table 5: Designed Detention & Water Quality Volumes
3. A total combined release rate of 14.64 cfs was determined for the proposed
detention facilities on the east parcel. This release rate was determined based on
the methodology utilized for previous projects in Fort Collins with a high
historic impervious area (approved Final Drainage Reports for “Scott Plaza” and
“Union on Elizabeth”). The methodology accounts for impervious area allowed
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 16 of 20
to be “grandfathered”. There is 1.52 acres (66,085 ft2) of impervious area within
the east half of the development site that drains towards the intersection of
Cherry Street and College Avenue. A 100-year discharge from this impervious
area was calculated to 14.62 cfs. There is 0.04 acres (1,863 ft2) of pervious area
within the eastern half of the development site which also drains to the
intersection of Cherry Street and College Avenue. A 2-year discharge from the
pervious area of 0.02 cfs was calculated. The sum of “grandfathered” impervious
area discharge and the 2-year pervious area discharge is 14.64 cfs for the east half
of the project site. The 14.64 cfs is considered as the allowable peak release rate
for the eastern half of the site.
4. A similar methodology, as described above, was used for the west half (parking
garage) side of the site. Because the west half of the site consists entirely of a
gravel lot, there was no 2-year historic pervious area to calculate. There is 0.35
acres (15,234 ft2) of impervious area within the west half of the development site
that drains towards the alley. A 100-year discharge from this “grandfathered”
impervious area was calculated to 3.42 cfs. The 3.42 cfs is considered as the
allowable peak release rate for the western half of the site. Due to grading
constraints along existing streets, portions of the west side are released
undetained. Therefore, the release rate for the detention vault on the west side
was throttled back to 3.39 cfs.
5. The FAA method was used to size the on-site detention volume.
M. Sizing of LID Facilities
Infiltration Gallery & Planter Boxes
6. The infiltration gallery was sized by first determining the required water quality
capture volume (WQCV) for Basins E1 - E5. A 12-hour drain time was used in
this calculation.
7. The WQCV for the infiltration gallery was then reduced by the available volume
in the planter boxes. The WQCV was calculated to be 2,035 cubic feet for the east
side improvements. Per FCSM requirements for rain gardens, the planter boxes
will be capable of treating a WQCV of 690 cubic feet to a depth of 1 foot.
Therefore, the minimum required WQCV within the infiltration gallery is 1,345
cubic feet (2,035 ft3 – 690 ft3 = 1,345 ft3).
8. Once the WQCV was identified, the minimum number of vaults needed to
achieve the minimum WQCV was calculated. This volume includes the adjacent
aggregates
9. The total release rate for the underground vaults wrapped in geofabric, with the
potential to constrict flows and resulting in sedimentation, was calculated to be
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 17 of 20
0.42 cfs. This rate was determined by multiplying the vault bottom square
footage x 0.35 gpm.
10. After completing the volume calculated utilizing the WQ flow rate into the
chamber and the calculated release rate through the fabric, the number of
chambers was increased as needed to confirm the resulting WQCV is provided
within the empty volume of the underground chambers. This is intended to
ensure the chambers do not become overwhelmed in the water quality storm
event before “discharging” flows into the surrounding aggregates.
11. Finally, additional chambers, without fabric, were added to provide the required
detention volume for the east side of the project.
Sand Filter Vault
12. The sand filter vault was sized by first determining the required water quality
capture volume (WQCV) for the parking garage footprint (Basin W2) assuming
100% imperviousness. A 12-hour drain time was used in this calculation.
IV. Conclusions
A. Compliance with Standards
1. The design elements comply without variation and meet all LID requirements.
2. The drainage design proposed with Morningstar/Block 23 complies with the City
of Fort Collins Master Drainage Plan for the Old Town Basin.
3. There are no FEMA regulatory floodplains associated with Morningstar/Block 23
development.
4. The drainage plan and stormwater management measures proposed with
Morningstar/Block 23 project are compliant with all applicable State and Federal
regulations governing stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit potential
damage associated with its stormwater runoff. Morningstar/Block 23 will detain
for existing pervious area converted to impervious areas at the 2-year existing
release rate.
Final Drainage Report March 17, 2021
Morningstar/Block 23 Page 18 of 20
V. References
City of Fort Collins Landscape Design Guidelines for Stormwater and Detention
Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility
Services.
Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by
Ordinance No. 159, 2018, and referenced in Section 26-500 of the City of Fort Collins
Municipal Code.
Soils Resource Report for Larimer County Area, Colorado, Natural Resources
Conservation Service, United States Department of Agriculture.
Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood
Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April
2008.
Appendix A
Hydrologic Computations
Project:Calc. By:
Location:Date:
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Rooftop 19,291 100%19,291 Rooftop 0 100%0
Concrete 14,886 100%14,886 Concrete 0 100%0
Asphalt 26,532 100%26,532 Asphalt 0 100%0
Gravel 13,439 40%5,376 Gravel 38,085 40%15,234
Landscaping 1,863 0%0 Landscaping 0 0%0
Total 76,011 66,085 Total 38,085 15,234
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Rooftop 56,647 100%56,647 Rooftop 26,308 100%26,308
Concrete 15,025 100%15,025 Concrete 1,283 100%1,283
Asphalt 2,356 100%2,356 Asphalt 0 100%0
Gravel 0 40%0 Gravel 5,949 40%2,380
Landscaping 1,983 0%0 Landscaping 4,545 0%0
Total 76,011 74,028 Total 38,085 29,971
7,943 14,737
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Rooftop 19,291 100%19,291 Rooftop 82,955 100%82,955
Concrete 14,886 100%14,886 Concrete 16,308 100%16,308
Asphalt 26,532 100%26,532 Asphalt 2,356 100%2,356
Gravel 51,524 40%20,610 Gravel 5,949 40%2,380
Landscaping 1,863 0%0 Landscaping 6,528 0%0
Total 114,096 81,319 Total 114,096 103,999
22,680Additional Impervious Area (SF)
Existing Developed
Onsite Impervious Areas by Location to Alley
Total Onsite Impervious Area
Additional Impervious Area (SF)Additional Impervious Area (SF)
Proposed Proposed
Onsite Impervious Areas
Impervious Area for East Side of Alley Impervious Area for West Side of Alley
Impervious Area for West Side of AlleyImpervious Area for East Side of Alley
Existing Existing
Morningstar/Block 23
Fort Collins, Colorado
F. Wegert
02/10/21
GCONTROLIRR CONTROLIRR CONTROLIRR / / / / / / / // / / / / / / // / / / / / / /GCONTROLIRR CONTROLIRR CONTROLIRR
DRAWN BY:SCALE:DATE:EXISTING VS PROPOSEDIMPERVIOUS AREASHEET NO:FORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631ENGINEERNGIEHTRONRN970.221.4158northernengineering.comP:\1204-004\DWG\DRNG\1204-004_IMPV_EAST.DWG
BLOCK 23 - MORNINGSTARFORT COLLINSCOLORADOFSWEXISTINGPROPOSED( IN FEET )01 INCH = 50 FEET5050ROOFTOPCONCRETEASPHALTSURFACEAREA (SF)% IMPERV.IMPERV.AREA (SF)19,29114,88626,532100%100%100%TOTALS76,01166,085TOTAL=19,29114,88626,532GRAVEL13,43940%5,3761" = 50'2/10/2021IMP 1LANDSCAPING1,8630%0ROOFTOPCONCRETEASPHALTSURFACEAREA (SF)% IMPERV.IMPERV.AREA (SF)56,64715,0252,356100%100%100%TOTALS76,01174,028TOTAL=56,64715,0252,356GRAVEL040%0LANDSCAPING1,9830%0
UD8
"
W
8" W
12" W12" W12" W12" W12" WTRAFFIC
VAULT
T S VAULT
ELEC
ELEC
ELEC
BRKR
E
VAULT
ELECFOFOFOFOFOFO
UD8
"
W
8" W
12" W12" W12" W12" W12" WTRAFFIC
VAULT
T S VAULT
ELEC
ELEC
ELEC
BRKR
E
VAULT
ELECFOFOFOFOFOFO
DRAWN BY:
SCALE:
DATE:
EXISTING VS PROPOSED
IMPERVIOUS AREA
SHEET NO:
FORT COLLINS: 301 North Howes Street, Suite 100, 80521
GREELEY: 820 8th Street, 80631
E N G I N E E R N GI
EHTRON R N
970.221.4158
northernengineering.com
P:\1204-004\DWG\DRNG\1204-004_IMPV_WEST.DWGBLOCK 23 - MORNINGSTAR
FORT COLLINS
COLORADO
FSW
EXISTING PROPOSED
( IN FEET )
0
1 INCH = 40 FEET
40 40
1" = 40'
2/10/2021
IMP 2
ROOFTOP
CONCRETE
ASPHALT
SURFACE
AREA (SF)% IMPERV.IMPERV.
AREA (SF)
0
0
0
100%
100%
100%
TOTALS 38,085 15,234TOTAL=
0
0
0
GRAVEL 38,085 40%15,234
LANDSCAPING 0 0%0
ROOFTOP
CONCRETE
ASPHALT
SURFACE
AREA (SF)% IMPERV.IMPERV.
AREA (SF)
26,308
1,238
0
100%
100%
100%
TOTALS 38,085 29,971TOTAL=
26,308
1,238
0
GRAVEL 5,949 40%2,380
LANDSCAPING 4,545 0%0
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
Runoff
Coefficient1
Percent
Impervious1
0.95 100%
0.95 90%
0.50 40%
0.50 40%
0.20 2%
0.20 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt,
Concrete (acres)Rooftop (acres)Pavers (acres)Gravel (acres)
Lawns, Clayey
Soil, Flat Slope <
2% (acres)
Lawns, Clayey
Soil, Flat Slope <
2% (acres)
Percent
Impervious C2*Cf C5*Cf C10*Cf C100*Cf
H-A1 13,803 0.317 0.177 0.000 0.000 0.093 0.000 0.05 68%0.71 0.71 0.71 0.88
H-A2 7,273 0.167 0.156 0.000 0.000 0.011 0.000 0.00 96%0.92 0.92 0.92 1.00
H-A3 4,931 0.113 0.082 0.000 0.000 0.013 0.000 0.02 77%0.78 0.78 0.78 0.97
H-B2 6,974 0.160 0.160 0.000 0.000 0.000 0.000 0.00 100%0.95 0.95 0.95 1.00
H-E1 17,005 0.390 0.292 0.053 0.000 0.003 0.000 0.04 87%0.86 0.86 0.86 1.00
H-E2 18,488 0.424 0.240 0.185 0.000 0.000 0.000 0.00 96%0.95 0.95 0.95 1.00
H-E3 4,020 0.092 0.024 0.050 0.000 0.019 0.000 0.00 82%0.86 0.86 0.86 1.00
H-E4 36,498 0.838 0.396 0.155 0.000 0.287 0.000 0.00 78%0.80 0.80 0.80 0.99
H-W1 1,238 0.028 0.000 0.000 0.000 0.028 0.000 0.00 40%0.50 0.50 0.50 0.63
H-W2 30,897 0.709 0.000 0.000 0.000 0.709 0.000 0.00 40%0.50 0.50 0.50 0.63
OS1 30,414 0.698 0.698 0.000 0.000 0.000 0.000 0.00 100%0.95 0.95 0.95 1.00
HW-Site 32,136 0.738 0.000 0.000 0.000 0.738 0.000 0.00 40%0.50 0.50 0.50 0.63
HW-Imp 32,136 0.738 0.000 0.000 0.000 0.738 0.000 0.00 40%0.50 0.50 0.50 0.63
HE-Site 76,011 1.745 0.951 0.443 0.000 0.309 0.000 0.04 84%0.85 0.85 0.85 1.00
HE-Imp 74,148 1.702 0.951 0.443 0.000 0.309 0.000 0.00 87%0.87 0.87 0.87 1.00
HE-Per 1,863 0.043 0.000 0.000 0.000 0.000 0.000 0.04 2%0.20 0.20 0.20 0.25
Total 141,128 3.240 1.526 0.443 0.000 1.163 0.000 0.00 74%0.76 0.76 0.76 0.95
HISTORIC RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Pavers
Gravel
Morningstar/Block 23
F. Wegert
December 16, 2020
Project:
Calculations By:
Date:
Character of Surface
Streets, Parking Lots, Roofs, Alleys, and Drives:
Lawns & Landscaping:
Combined Basins & Routed Basins3,4,5,6,7
Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).
Lawns, Clayey Soil, Flat Slope < 2%
USDA SOIL TYPE: A
Lawns, Clayey Soil, Flat Slope < 2%Composite Runoff Coefficient2
Notes:
1) Runoff coefficients per Tables 3.2-1 & 3.2-2 of the Fort Collins Stormwater Manual. Percent impervious per Tables 4.1-2 & 4.1-3 of the Fort Collins Stormwater Manual.
2) Composite Runoff Coefficient adjusted per Table 3.2 -3 of the Fort Collins Stormwater Manual.
3) HW-Site is historic basin for the west side of the project. The basin is borderd by Cherry Street, the Burlington Northern Railroad, Old Town Flats, and the a lley.
4) HE-Site is historic basin for the east side of the project. The basin is borderd by Cherry Street, Ciollege Avenue, Maple Street, and the alley.
5) HW-Imp is only the impervious area within Basin HW-Site.
6) HE-Imp is only the impervious area within Basin HE-Site.
7) HE-Per is only the permeable are within Basin HE-Site.
Project:
Calculations By:
Date:
C2*Cf
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Ti
2-Yr
(min)
Ti
10-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Max.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Max.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Max.
Tc 100-Yr
(min)
Tc
100-Yr
(min)
h-a1 H-A1 0.71 22 80.00 79.41 2.68%2.5 2.5 1.4 380 79.41 77.23 0.57 1.51 4.18 N/A N/A N/A 12.23 6.66 12.23 6.66 12.23 5.55
h-a2 H-A2 0.92 33 78.50 77.69 2.45%1.4 1.4 0.8 203 77.69 76.94 0.37 1.22 2.78 N/A N/A N/A 11.31 5.00 11.31 5.00 11.31 5.00
h-a3 H-A3 0.78 37 81.05 80.65 1.08%3.6 3.6 1.4 174 80.65 77.22 1.97 2.81 1.03 N/A N/A N/A 11.17 5.00 11.17 5.00 11.17 5.00
h-b4 H-B2 0.95 18 81.05 80.88 0.94%1.2 1.2 0.8 392 80.88 77.39 0.89 1.89 3.46 N/A N/A N/A 12.28 5.00 12.28 5.00 12.28 5.00
h-a1 H-E1 0.86 105 79.50 78.06 1.37%4.1 4.1 1.7 267 78.06 77.23 0.31 1.12 3.99 N/A N/A N/A 12.07 8.05 12.07 8.05 12.07 5.72
h-a3 H-E2 0.95 148 78.70 77.93 0.52%4.2 4.2 2.8 175 77.93 76.94 0.57 1.50 1.94 N/A N/A N/A 11.79 6.18 11.79 6.18 11.79 5.00
h-a5 H-E3 0.86 51 80.64 80.23 0.80%3.5 3.5 1.4 136 80.23 77.22 2.21 2.98 0.76 N/A N/A N/A 11.04 5.00 11.04 5.00 11.04 5.00
h-e4 H-E4 0.80 200 80.88 78.62 1.13%7.7 7.7 2.7 139 78.62 77.39 0.88 1.88 1.23 N/A N/A N/A 11.88 8.95 11.88 8.95 11.88 5.00
h-a1 H-W1 0.50 105 80.23 78.85 1.31%10.5 10.5 8.3 342 78.85 77.23 0.47 1.38 4.14 N/A N/A N/A 12.48 12.48 12.48 12.48 12.48 12.45
h-w2 H-W2 0.50 135 83.01 79.43 2.65%9.4 9.4 7.5 N/A N/A N/A 107 79.43 78.88 0.51%0.11 16.58 11.34 11.34 11.34 11.34 11.34 24.04
os1 OS1 0.95 37 80.20 79.71 1.32%1.6 1.6 1.0 260 79.71 77.16 0.98 1.98 2.19 N/A N/A N/A 11.65 5.00 11.65 5.00 11.65 5.00
h-b5 HW-Site 0.50 135 83.01 79.43 2.65%9.4 9.4 7.5 N/A N/A N/A 107 79.43 78.88 0.51%0.11 16.58 11.34 11.34 11.34 11.34 11.34 24.04
h-b5 HW-Imp 0.50 135 83.01 79.43 2.65%9.4 9.4 7.5 N/A N/A N/A 107 79.43 78.88 0.51%0.11 16.58 11.34 11.34 11.34 11.34 11.34 24.04
h-a1 HE-Site 0.85 105 79.50 78.06 1.37%4.3 4.3 1.7 267 78.06 77.23 0.31 1.12 3.99 N/A N/A N/A 12.07 8.27 12.07 8.27 12.07 5.72
h-a1 HE-Imp 0.87 105 79.50 78.06 1.37%4.0 4.0 1.7 267 78.06 77.23 0.31 1.12 3.99 N/A N/A N/A 12.07 7.98 12.07 7.98 12.07 5.72
h-a1 HE-Per 0.20 105 79.50 78.06 1.37%15.5 15.5 14.7 267 78.06 77.23 0.31 1.12 3.99 N/A N/A N/A 12.07 12.07 12.07 12.07 12.07 18.65
h-a1 Total 0.76 135 83.01 79.43 2.65%5.4 5.4 2.4 300 78.88 77.23 0.55 1.48 3.37 107 79.43 78.88 0.51%0.11 16.58 13.01 13.01 13.01 13.01 13.01 22.37
Velocity (Swale Flow), V = 15·S ½
F. Wegert
Tt = L / 60V (Equation 6-4 per MHFD)
Tc = Ti + Tt (Equation 6-2 per MHFD)
Intensity, i (per Table 3.4-1 of the Fort Collins Stormwater Manual)
Velocity (Gutter Flow), V = 20·S ½
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Combined Basins & Routed Basins
Overland Flow, Time of Concentration:
HISTORIC TIME OF CONCENTRATION COMPUTATIONS
Channelized Flow Swale Flow
Design
Point Basin(s)
Overland Flow Time of Concentration
Morningstar/Block 23
Gutter/Swale Flow, Time of Concentration:
December 16, 2020
(Equation 6-4 per MHFD)
(Equation 3.3-2 per Fort Collins
Stormwater Manual)
}
𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
Notes:
1)Add 4900 to all elevations.
Page 2 of 3
C2 C10 C100 I2 I10 I100 Q2 Q10 Q100
h-a1 H-A1 0.317 0.71 0.71 0.88 2.60 4.44 9.06 0.58 0.99 2.54
h-a2 H-A2 0.167 0.92 0.92 1.00 2.85 4.87 9.95 0.44 0.75 1.66
h-a3 H-A3 0.113 0.78 0.78 0.97 2.85 4.87 9.95 0.25 0.43 1.10
h-b4 H-B2 0.160 0.95 0.95 1.00 2.85 4.87 9.95 0.43 0.74 1.59
h-a1 H-E1 0.390 0.86 0.86 1.00 2.40 4.10 8.38 0.81 1.38 3.27
h-a3 H-E2 0.424 0.95 0.95 1.00 2.67 4.56 9.31 1.08 1.84 3.95
h-a5 H-E3 0.092 0.86 0.86 1.00 2.85 4.87 9.95 0.23 0.39 0.92
h-e4 H-E4 0.838 0.80 0.80 0.99 2.35 4.02 8.21 1.57 2.68 6.84
h-a1 H-W1 0.028 0.50 0.50 0.63 2.05 3.50 7.16 0.03 0.05 0.13
h-w2 H-W2 0.709 0.50 0.50 0.63 2.13 3.63 7.42 0.76 1.29 3.29
os1 OS1 0.698 0.95 0.95 1.00 2.85 4.87 9.95 1.89 3.23 6.95
h-b5 HW-Site 0.738 0.50 0.50 0.63 2.13 3.63 7.42 0.79 1.34 3.42
h-b5 HW-Imp 0.738 0.50 0.50 0.63 2.13 3.63 7.42 0.79 1.34 3.42
h-a1 HE-Site 1.745 0.85 0.85 1.00 2.40 4.10 8.38 3.57 6.10 14.62
h-a1 HE-Imp 1.702 0.87 0.87 1.00 2.46 4.21 8.59 3.64 6.22 14.62
h-a1 HE-Per 0.043 0.20 0.20 0.25 2.05 3.50 7.16 0.02 0.03 0.08
h-a1 Total 3.240 0.76 0.76 0.95 1.98 3.39 6.92 4.85 8.31 21.21
Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual
HISTORIC DIRECT RUNOFF COMPUTATIONS
Intensity (in/hr)Flow (cfs)
Morningstar/Block 23
F. Wegert
December 16, 2020
Overland Flow, Time of Concentration:
Project:
Gutter/Swale Flow, Time of Concentration:Calculations By:
Date:Tt = L / 60V (Equation 6-4 per MHFD)
Tc = Ti + Tt (Equation 6-2 per MHFD)
Combined Basins & Routed Basins
Velocity (Swale Flow), V = 15·S ½
Velocity (Gutter Flow), V = 20·S ½
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Design
Point Basin Area
(ac.)
Runoff C
(Equation 6-4 per
(Equation 6-3 per
Fort Collins 𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
Page 3 of 3
Runoff
Coefficient1
Percent
Impervious1
0.95 100%
0.95 90%
0.50 40%
0.50 40%
0.20 2%
0.10 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt,
Concrete (acres)Rooftop (acres)Pavers (acres)Gravel (acres)
Lawns, Clayey
Soil, Flat Slope <
2% (acres)
Lawns, Sandy
Soil, Flat Slope <
2% (acres)
Percent
Impervious C2*Cf C5*Cf C10*Cf C100*Cf
A1 9,974 0.229 0.139 0.000 0.000 0.000 0.000 0.090 62%0.62 0.62 0.62 0.77
A2 12,404 0.285 0.236 0.000 0.000 0.000 0.000 0.048 83%0.81 0.81 0.81 1.00
A3 12,488 0.287 0.261 0.000 0.000 0.000 0.000 0.025 91%0.88 0.88 0.88 1.00
B1 3,829 0.088 0.055 0.000 0.000 0.002 0.000 0.031 64%0.64 0.64 0.64 0.80
B2 6,998 0.161 0.156 0.000 0.000 0.000 0.000 0.004 97%0.93 0.93 0.93 1.00
C1 3,699 0.085 0.085 0.000 0.000 0.000 0.000 0.000 100%0.95 0.95 0.95 1.00
C2 4,918 0.113 0.113 0.000 0.000 0.000 0.000 0.000 100%0.95 0.95 0.95 1.00
E1 17,353 0.398 0.008 0.370 0.000 0.000 0.000 0.020 86%0.91 0.91 0.91 1.00
E2 13,459 0.309 0.018 0.291 0.000 0.000 0.000 0.000 91%0.95 0.95 0.95 1.00
E3 9,299 0.213 0.004 0.210 0.000 0.000 0.000 0.000 90%0.95 0.95 0.95 1.00
E4 26,769 0.615 0.162 0.437 0.000 0.000 0.000 0.016 90%0.93 0.93 0.93 1.00
E5 514 0.012 0.012 0.000 0.000 0.000 0.000 0.000 100%0.95 0.95 0.95 1.00
W1 453 0.010 0.001 0.000 0.000 0.000 0.000 0.010 7%0.15 0.15 0.15 0.18
W2 26,662 0.612 0.000 0.612 0.000 0.000 0.000 0.000 90%0.95 0.95 0.95 1.00
W3 2,078 0.048 0.010 0.000 0.000 0.000 0.000 0.038 22%0.27 0.27 0.27 0.34
W4 2,942 0.068 0.000 0.000 0.000 0.000 0.000 0.068 2%0.10 0.10 0.10 0.13
OS1 30,414 0.698 0.698 0.000 0.000 0.000 0.000 0.000 100%0.95 0.95 0.95 1.00
Cherry 14,256 0.327 0.195 0.000 0.000 0.002 0.000 0.131 60%0.61 0.61 0.61 0.76
College 12,404 0.285 0.236 0.000 0.000 0.000 0.000 0.048 83%0.81 0.81 0.81 1.00
Maple 12,488 0.287 0.261 0.000 0.000 0.000 0.000 0.025 91%0.88 0.88 0.88 1.00
Alley 35,845 0.823 0.328 0.437 0.000 0.000 0.000 0.059 88%0.89 0.89 0.89 1.00
East 76,011 1.745 0.402 1.307 0.000 0.000 0.000 0.036 90%0.93 0.93 0.93 1.00
West 32,135 0.738 0.010 0.612 0.000 0.000 0.000 0.116 76%0.82 0.82 0.82 1.00
Total Site 99,529 2.285 0.214 1.919 0.000 0.000 0.000 0.152 85%0.89 0.89 0.89 1.00
Total 153,839 3.532 1.260 1.919 0.000 0.002 0.000 0.351 85%0.87 0.87 0.87 1.00
USDA SOIL TYPE: A
Lawns, Clayey Soil, Flat Slope < 2%Composite Runoff Coefficient2
1) Runoff coefficients per Tables 3.2-1 & 3.2 of the FCSM. Percent impervious per Tables 4.1-2 & 4.1-3 of the FCSM.
Combined & Routed Basins3,4,5,6,7,8
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).
Lawns, Sandy Soil, Flat Slope < 2%
Lawns and Landscaping:
DEVELOPED RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Pavers
Gravel
Morningstar/Block 23
F. Wegert
December 16, 2020
Project:
Calculations By:
Date:
Character of Surface
Streets, Parking Lots, Roofs, Alleys, and Drives:
Notes:
3) Cherry Basin includes all basins that surface drain towards Cherry Street (A1, B1, & W1). The design point for Cherry are the
two existing type-R inlets located at the southwest corner of the intersection of Cherry Street and College Avenue.
4) College Basin includes all basins that surface drain towards College Avenue (A2). The design point for College is the existing
combination inlet at the northwest corner of College Avenue and Maple Street.
5) Maple Basin includes all basins that surface drain towards Maple Street (A3). The design point for Maple is a proposed inlet
on Maple Street west of the intersection with College Avene.
6) Alley Basin includes all basins that drains towards within the alley (B2, E4, & W3). The design point for Alley are the
proposed inlets along the east side of the alley.
7) East (Site) Basin includes all basins on the east parcel (C1, C2, E1, E2, E3, & E4). Primary purpose of East (Site) Basin is to
determine the percent impervious for the east parcel.
8) West (Site) Basin includes all basins on the west parcel (W1, W2, W3, & W4). Primary purpose of West (Site) Basin is to
Page 1 of 3
Project:
Calculations By:
Date:
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Ti
2-Yr
(min)
Ti
10-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Max.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Max.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Max.
Tc 100-Yr
(min)
Tc
100-Yr
(min)
a1 A1 22 79.38 78.43 4.32%2.6 2.6 1.8 292 78.43 77.19 0.42 1.30 3.73 N/A N/A N/A 11.74 6.34 11.74 6.34 11.74 5.51
a2 A2 32 79.18 77.69 4.66%1.9 1.9 0.6 203 77.69 76.98 0.35 1.18 2.86 N/A N/A N/A 11.31 5.00 11.31 5.00 11.31 5.00
a3 A3 47 81.97 81.13 1.79%2.4 2.4 1.1 145 81.13 78.59 1.75 2.65 0.91 N/A N/A N/A 11.07 5.00 11.07 5.00 11.07 5.00
b1 B1 22 80.91 80.47 2.00%3.2 3.2 2.1 145 80.47 78.55 1.32 2.30 1.05 N/A N/A N/A 10.93 5.00 10.93 5.00 10.93 5.00
b2 B2 21 81.11 80.84 1.29%1.4 1.4 0.8 245 80.84 79.41 0.58 1.53 2.67 N/A N/A N/A 11.48 5.00 11.48 5.00 11.48 5.00
c1 C1 55 80.27 79.72 1.00%2.1 2.1 1.4 N/A N/A N/A N/A N/A N/A 10.31 5.00 10.31 5.00 10.31 5.00
c2 C2 56 80.27 79.71 1.00%2.1 2.1 1.4 N/A N/A N/A N/A N/A N/A 10.31 5.00 10.31 5.00 10.31 5.00
e1 E1 76 80.27 79.73 0.71%3.5 3.5 1.8 241 79.73 77.19 1.05 2.05 1.96 N/A N/A N/A 11.76 5.48 11.76 5.48 11.76 5.00
e2 E2 128 80.27 77.69 2.02%2.5 2.5 1.7 203 77.69 76.98 0.35 1.18 2.86 N/A N/A N/A 11.84 5.37 11.84 5.37 11.84 5.00
e3 E3 101 80.27 78.92 1.34%2.6 2.6 1.7 39 78.92 78.59 0.85 1.84 0.35 N/A N/A N/A 10.78 5.00 10.78 5.00 10.78 5.00
e4 E4 62 80.27 80.21 0.10%5.5 5.5 3.2 183 80.21 79.41 0.44 1.32 2.31 N/A N/A N/A 11.36 7.82 11.36 7.82 11.36 5.51
e5 E5 16 79.37 79.08 1.81%0.9 0.9 0.6 35 79.08 78.90 0.51 1.43 0.41 N/A N/A N/A 10.28 5.00 10.28 5.00 10.28 5.00
w1 W1 22 80.91 80.47 2.00%6.6 6.6 6.4 120 80.47 78.77 1.42 2.38 0.84 N/A N/A N/A 10.79 7.47 10.79 7.47 10.79 7.22
w2 W2 120 83.61 79.31 3.58%2.0 2.0 1.3 145 79.31 77.28 1.40 2.37 1.02 N/A N/A N/A 11.47 5.00 11.47 5.00 11.47 5.00
w3 W3 5 82.90 82.80 2.00%2.8 2.8 2.5 175 82.80 79.13 2.10 2.90 1.01 N/A N/A N/A 11.00 5.00 11.00 5.00 11.00 5.00
w4 W4 15 83.31 83.01 2.00%5.7 5.7 5.6 220 83.01 79.77 1.47 2.43 1.51 N/A N/A N/A 11.31 7.26 11.31 7.26 11.31 7.12
os1 OS1 37 80.20 79.71 1.32%2.6 2.6 1.0 260 79.71 77.16 0.98 1.98 2.19 N/A N/A N/A 11.65 5.00 11.65 5.00 11.65 5.00
a1 Cherry 22 80.91 80.47 2.00%3.4 3.4 2.4 448 80.47 77.19 0.73 1.71 4.36 N/A N/A N/A 12.61 7.79 12.61 7.79 12.61 6.73
a2 College 32 79.18 77.69 4.66%1.9 1.9 0.6 203 77.69 76.98 0.35 1.18 2.86 N/A N/A N/A 11.31 5.00 11.31 5.00 11.31 5.00
a3 Maple 47 81.97 81.13 1.79%2.4 2.4 1.1 145 81.13 78.59 1.75 2.65 0.91 N/A N/A N/A 11.07 5.00 11.07 5.00 11.07 5.00
b2 Alley 21 81.11 80.84 1.29%1.7 1.7 0.8 245 80.84 79.41 0.58 1.53 2.67 N/A N/A N/A 11.48 5.00 11.48 5.00 11.48 5.00
a1 East 22 80.91 80.47 2.00%1.2 1.2 0.7 120 80.47 78.90 1.31 2.29 0.87 N/A N/A N/A 10.79 5.00 10.79 5.00 10.79 5.00
w2 West 22 79.38 78.43 4.32%1.5 1.5 0.5 292 78.43 77.19 0.42 1.30 3.73 N/A N/A N/A 11.74 5.26 11.74 5.26 11.74 5.00
a1 Total 22 79.38 78.43 4.32%1.3 1.3 0.5 292 78.43 77.19 0.42 1.30 3.73 N/A N/A N/A 11.74 5.00 11.74 5.00 11.74 5.00
Combined Basins & Routed Basins
Tt = L / 60V (Equation 6-4 per MHFD)
Tc = Ti + Tt (Equation 6-2 per MHFD)
Intensity, i (per Table 3.4-1 of the Fort Collins Stormwater Manual)
Velocity (Gutter Flow), V = 20·S ½
Velocity (Swale Flow), V = 15·S ½
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Overland Flow, Time of Concentration:
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Channelized Flow Swale Flow
Design
Point Basin(s)
Overland Flow Time of Concentration
Morningstar/Block 23
F. Wegert
December 16, 2020
Gutter/Swale Flow, Time of Concentration:
(Equation 6-4 per MHFD)
(Equation 3.3-2 per Fort Collins
Stormwater Manual)
}
𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
Notes:
1)Add 4900 to all elevations.
Page 2 of 3
Tc2 Tc10 Tc100 C2 C10 C100
I2
(in/hr)
I10
(in/hr)
I100
(in/hr)
QWQ
(cfs)
Q2
(cfs)
Q10
(cfs)
Q100
(cfs)
a1 A1 0.229 6.34 6.34 5.51 0.62 0.62 0.77 2.67 4.56 9.31 0.19 0.4 0.6 1.6
a2 A2 0.285 5.00 5.00 5.00 0.81 0.81 1.00 2.85 4.87 9.95 0.33 0.7 1.1 2.8
a3 A3 0.287 5.00 5.00 5.00 0.88 0.88 1.00 2.85 4.87 9.95 0.36 0.7 1.2 2.9
b1 B1 0.088 5.00 5.00 5.00 0.64 0.64 0.80 2.85 4.87 9.95 0.08 0.2 0.3 0.7
b2 B2 0.161 5.00 5.00 5.00 0.93 0.93 1.00 2.85 4.87 9.95 0.21 0.4 0.7 1.6
c1 C1 0.085 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.11 0.2 0.4 0.8
c2 C2 0.113 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.15 0.3 0.5 1.1
e1 E1 0.398 5.48 5.48 5.00 0.91 0.91 1.00 2.85 4.87 9.95 0.51 1.0 1.8 4.0
e2 E2 0.309 5.37 5.37 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.42 0.8 1.4 3.1
e3 E3 0.213 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.29 0.6 1.0 2.1
e4 E4 0.615 7.82 7.82 5.51 0.93 0.93 1.00 2.46 4.21 8.59 0.70 1.4 2.4 5.3
e5 E5 0.012 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.02 0.0 0.1 0.1
w1 W1 0.010 7.47 7.47 7.22 0.15 0.15 0.18 2.52 4.31 8.80 0.00 0.0 0.0 0.0
w2 W2 0.612 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.83 1.7 2.8 6.1
w3 W3 0.048 5.00 5.00 5.00 0.27 0.27 0.34 2.85 4.87 9.95 0.02 0.0 0.1 0.2
w4 W4 0.068 7.26 7.26 7.12 0.10 0.10 0.13 2.52 4.31 8.80 0.01 0.0 0.0 0.1
os1 OS1 0.698 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.95 1.9 3.2 6.9
a1 Cherry 0.327 7.79 7.79 6.73 0.61 0.61 0.76 2.46 4.21 8.59 0.24 0.5 0.8 2.1
a2 College 0.285 5.00 5.00 5.00 0.81 0.81 1.00 2.85 4.87 9.95 0.33 0.7 1.1 2.8
a3 Maple 0.287 5.00 5.00 5.00 0.88 0.88 1.00 2.85 4.87 9.95 0.36 0.7 1.2 2.9
b2 Alley 0.823 5.00 5.00 5.00 0.89 0.89 1.00 2.85 4.87 9.95 1.04 2.1 3.6 8.2
a1 East 1.745 5.00 5.00 5.00 0.93 0.93 1.00 2.85 4.87 9.95 2.32 4.6 7.9 17.4
w2 West 0.738 5.26 5.26 5.00 0.82 0.82 1.00 2.85 4.87 9.95 0.86 1.7 2.9 7.3
a1 Total 3.532 5.00 5.00 5.00 0.87 0.87 1.00 2.85 4.87 9.95 4.35 8.7 14.9 35.1
Flow
Combined Basins & Routed Basins
DEVELOPED DIRECT RUNOFF COMPUTATIONS
Intensity
Morningstar/Block 23
F. Wegert
December 16, 2020
Project:
Calculations By:
Overland Flow, Time of Concentration:
Gutter/Swale Flow, Time of Concentration:
Date:
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Design
Point Basin Area
(acres)
Runoff CTc (Min)
Velocity (Gutter Flow), V = 20·S ½
Velocity (Swale Flow), V = 15·S ½
Tt = L / 60V (Equation 6-4 per MHFD)
Tc = Ti + Tt (Equation 6-2 per MHFD)
Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual
(Equation 6-4 per MHFD)
(Equation 6-3 per Fort
Collins Stormwater Manual)
}
𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
Page 3 of 3
Appendix B
Hydraulic Calculations
Storm Sewer A - 100-Year
Storm Sewer A - 100-Year
Storm Sewer A - 100-Year
Storm Sewer A7 - 100-Year
Storm Sewer A8 - 100-Year
Storm Sewer B - 100-Year
Storm Sewer B - 100-Year
Storm Sewer B - 100-Year
Storm Sewer B5 - 100-Year
Area Inlet Performance Curve:
Inlet A7-1
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 2(L + W)
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:FC Area Inlet
Length of Grate (ft):1.98
Width of Grate (ft):1.35
Open Area of Grate (ft2):2.28
Flowline Elevation (ft):4978.73
Allowable Capacity:0.50
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4978.73 0.00 0.00 0.00
0.10 4978.83 0.32 1.94 0.32
0.18 4978.91 0.76 2.60 0.76 <-10-Year
0.20 4978.93 0.89 2.74 0.89
0.30 4979.03 1.64 3.35 1.64
0.37 4979.10 2.25 3.72 2.25 <-100-Year
0.40 4979.13 2.53 3.87 2.53
0.50 4979.23 3.54 4.33 3.54
0.53 4979.26 3.86 4.46 3.86 <-Overflow
0.60 4979.33 4.65 4.74 4.65
0.80 4979.53 7.16 5.48 5.48
100-Year Design Flow = 2.24 cfs 10-Year Design Flow = 0.70 cfs
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
Will receive 100-year overflow from Inlet A10-1.
Area Inlet Performance Curve:
Inlet A10-1
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 2(L + W)
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:FC Area Inlet
Length of Grate (ft):1.98
Width of Grate (ft):1.35
Open Area of Grate (ft2):2.28
Flowline Elevation (ft):4979.07
Allowable Capacity:0.50
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4979.07 0.00 0.00 0.00
0.10 4979.17 0.32 1.94 0.32
0.18 4979.25 0.76 2.60 0.76 <-10-Year
0.20 4979.27 0.89 2.74 0.89 <-Overflow
0.29 4979.36 1.56 3.30 1.56 <-100-Year
0.30 4979.37 1.64 3.35 1.64
0.40 4979.47 2.53 3.87 2.53
0.50 4979.57 3.54 4.33 3.54
0.53 4979.60 3.86 4.46 3.86
0.60 4979.67 4.65 4.74 4.65
0.80 4979.87 7.16 5.48 5.48
100-Year Design Flow = 1.56 cfs 10-Year Design Flow = 0.70 cfs
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
100-year will overflow into Inlet A7-1.
Area Inlet Performance Curve:
North Rain Garden Inlets (Basin A10-8)
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 3.1416*Dia.of grate
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:Nyloplast 24" Dome
Diameter of Grate (ft):2
Open Area of Grate (ft2):1.88
Rim Elevation (ft):4981.320
Reduction Factor:50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4981.32 0.00 0.00 0.00
0.20 4981.52 0.84 2.27 0.84
0.28 4981.60 1.40 2.68 1.40 <-10-Year
0.30 4981.62 1.55 2.77 1.55
0.40 4981.72 2.38 3.20 2.38
0.47 4981.79 3.04 3.47 3.04 <-100-Year
0.60 4981.92 4.38 3.92 3.92
0.80 4982.12 6.74 4.53 4.53
1.00 4982.32 9.42 5.07 5.07 <-Overflow
1.20 4982.52 12.39 5.55 5.55
1.40 4982.72 15.61 5.99 5.99
100-Year Design Flow = 3.05 cfs 10-Year Design Flow = 1.35 cfs
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
Two (2) inlets will be required for north rain
garden. Calculations are for one inlet.
Area Inlet Performance Curve:
North Rain Garden Inlet (Basin A10-9)
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 3.1416*Dia.of grate
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:Nyloplast 24" Dome
Diameter of Grate (ft):2
Open Area of Grate (ft2):1.88
Rim Elevation (ft):4981.320
Reduction Factor:50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4981.32 0.00 0.00 0.00
0.20 4981.52 0.84 2.27 0.84
0.28 4981.60 1.40 2.68 1.40 <-10-Year
0.30 4981.62 1.55 2.77 1.55
0.40 4981.72 2.38 3.20 2.38
0.47 4981.79 3.04 3.47 3.04 <-100-Year
0.60 4981.92 4.38 3.92 3.92
0.80 4982.12 6.74 4.53 4.53
1.00 4982.32 9.42 5.07 5.07 <-Overflow
1.20 4982.52 12.39 5.55 5.55
1.40 4982.72 15.61 5.99 5.99
100-Year Design Flow = 3.05 cfs 10-Year Design Flow = 1.35 cfs
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
Two (2) inlets will be required for north rain
garden. Calculations are for one inlet.
Area Inlet Performance Curve:
North Middle Rain Garden Inlet (Basin A10-6B)
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 3.1416*Dia.of grate
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:Nyloplast 24" Dome
Diameter of Grate (ft):2
Open Area of Grate (ft2):1.88
Rim Elevation (ft):4981.320
Reduction Factor:50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4981.32 0.00 0.00 0.00
0.20 4981.52 0.84 2.27 0.84
0.30 4981.62 1.55 2.77 1.55 <-10-Year
0.40 4981.72 2.38 3.20 2.38
0.50 4981.82 3.33 3.58 3.33 <-100-Year
0.60 4981.92 4.38 3.92 3.92
0.80 4982.12 6.74 4.53 4.53
1.00 4982.32 9.42 5.07 5.07 <-Overflow
1.20 4982.52 12.39 5.55 5.55
1.40 4982.72 15.61 5.99 5.99
1.60 4982.92 19.07 6.41 6.41
100-Year Design Flow = 3.30 cfs 10-Year Design Flow = 1.50 cfs
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
Area Inlet Performance Curve:
South Middle Rain Garden Inlet (Basin A10-3A-1)
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 3.1416*Dia.of grate
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:Nyloplast 18" Dome
Diameter of Grate (ft):1.5
Open Area of Grate (ft2):1.06
Rim Elevation (ft):4981.320
Reduction Factor:50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4981.32 0.00 0.00 0.00
0.20 4981.52 0.63 1.27 0.63
0.22 4981.54 0.73 1.34 0.73 <-10-Year
0.30 4981.62 1.16 1.56 1.16
0.37 4981.69 1.59 1.73 1.59 <-100-Year
0.40 4981.72 1.79 1.80 1.79
0.60 4981.92 3.29 2.21 2.21
0.80 4982.12 5.06 2.55 2.55
1.00 4982.32 7.07 2.85 2.85 <-Overflow
1.20 4982.52 9.29 3.12 3.12
1.40 4982.72 11.71 3.37 3.37
100-Year Design Flow = 1.60 cfs 10-Year Design Flow =0.70 cfs
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
Area Inlet Performance Curve:
South Rain Garden Inlet (Basin A10-7A)
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 3.1416*Dia.of grate
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:Nyloplast 24" Dome
Diameter of Grate (ft):2
Open Area of Grate (ft2):1.88
Rim Elevation (ft):4981.320
Reduction Factor:50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4981.32 0.00 0.00 0.00
0.20 4981.52 0.84 2.27 0.84
0.26 4981.58 1.25 2.58 1.25 <-10-Year
0.30 4981.62 1.55 2.77 1.55
0.40 4981.72 2.38 3.20 2.38
0.60 4981.92 4.38 3.92 3.92
0.80 4982.12 6.74 4.53 4.53 <-100-Year
1.00 4982.32 9.42 5.07 5.07 <-Overflow
1.20 4982.52 12.39 5.55 5.55
1.60 4982.92 19.07 6.41 6.41
2.00 4983.32 26.66 7.16 7.16
100-Year Design Flow = 4.5 cfs 10-Year Design Flow = 1.20 cfs
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
0.00
5.00
10.00
15.00
20.00
25.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =0.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.013
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =60.0 ft
Gutter Width W =2.00 ft
Street Transverse Slope SX =0.025 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.013
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =26.0 26.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 18.0 inches
Check boxes are not applicable in SUMP conditions
MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs
Version 4.05 Released March 2017
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Enter Your Project Name Here
Inlet B3
UD-Inlet_v4.05.xlsm, Inlet B3 10/29/2020, 9:53 PM
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from above)alocal =2.00 2.00 inches
Number of Unit Inlets (Grate or Curb Opening)No =2 2
Water Depth at Flowline (outside of local depression)Ponding Depth =6.0 9.2 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) =3.00 3.00 feet
Width of a Unit Grate Wo =1.73 1.73 feet
Area Opening Ratio for a Grate (typical values 0.15-0.90)Aratio =0.43 0.43
Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =0.50 0.50
Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =3.30 3.30
Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =0.60 0.60
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) =3.00 3.00 feet
Height of Vertical Curb Opening in Inches Hvert =6.50 6.50 inches
Height of Curb Orifice Throat in Inches Hthroat =5.25 5.25 inches
Angle of Throat (see USDCM Figure ST-5)Theta =0.00 0.00 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =2.00 2.00 feet
Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =0.10 0.10
Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =3.70 3.70
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =0.66 0.66
Low Head Performance Reduction (Calculated)MINOR MAJOR
Depth for Grate Midwidth dGrate =0.523 0.789 ft
Depth for Curb Opening Weir Equation dCurb =0.33 0.60 ft
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination =0.71 1.00
Curb Opening Performance Reduction Factor for Long Inlets RFCurb =1.00 1.00
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate =0.71 1.00
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition)Qa =5.3 15.5 cfs
Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =2.4 5.8 cfs
CDOT/Denver 13 Combination
INLET IN A SUMP OR SAG LOCATION
Version 4.05 Released March 2017
H-VertH-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT/Denver 13 Combination
Override Depths
UD-Inlet_v4.05.xlsm, Inlet B3 10/29/2020, 9:53 PM
Appendix C
Water Quality/LID Design Computations
Morningstar/Block 23 Calc. By:
Fort Collins, Colorado Date:
74,028 sf
29,971 sf
103,999 sf
75%
77,999 sf
54,057 sf
12,023 sf
26,306 sf
92,386 sf
88.8%
2,035 cf
817 cf
2,852 cf
2,035 cf
785 cf
1,250 cf
17 1,273 cf
13 974 cf
2,247 cf
785 cf
3,032 cf
1,066 cf
1,384 cf
2,450 cf
1,215 cf
2,037 cf
3,252 cfDetention Pond Volume
Storage and Water Quality Volume
East Side
Sand Filter Treatment Area
Total Treatment Area
Percent Total Project Area Treated
Required Water Quality Volume
Required Detention Volume
Total Required Volume
Volume of Planters/Rain Gardens
Required WQ volume in Chambers
Required Detention Volume
Total Required Volume
Volume in Chambers
Required Water Quality Volume
Required Water Quality Volume
Onsite LID Treatment
F. Wegert
Rain Garden Planters
Other Treatement
Impervious Area (West Side)
Total Impervious Area
Project Summary
Impervious Area (East Side)
Target Treatment Percentage
Minimum Area to be Treated by LID measures
StormTech Chambers
StormTech Treatment Area (Onsite)
Design Detention Volume
Project:
Location:
Isolator Row Chambers (WQ) Volume
Standard Chambers (Storage) Volume
Design Water Quality Volume
Volume in Rain Gardens
Total Available Volume
West Side
03/17/21
Project Number:
Project Name:
Project Location:
Undeveloped Basins
Design
Point Notes
East Side
Impervious Area 3.64 cfs 14.62 cfs h-a1 Flowrate from impervious areas.
Pervious Area 0.02 cfs 0.08 cfs h-a1 Flowrate from pervious areas.
West Side
Impervious Area 0.79 cfs 3.42 cfs h-b5 Flowrate from impervious areas.
Pervious Area 0.00 cfs 0.00 cfs h-b5 The entire west side is gravel. Therefore, no pervious areas.
Developed Basins
Design
Point Notes
East Side
Total Flowrate 2.32 cfs 17.40 cfs a1 Total flowrate from east side.
West Side
Total Flowrate 0.86 cfs 7.30 cfs w2 Total flowrate from west side.
East Side
Impervious 100-Year 14.62 cfs Historic Q100 from impervious areas.
Pervious 2-Year 0.02 cfs Historic Q2 from pervious areas.
Allowable Release Rate 14.64 cfs Total of 100-year release rate for entire east side.
West Side
Impervious 100-Year 3.42 cfs Historic Q100 from impervious areas.
Pervious 2-Year 0.00 cfs Historic Q2 from pervious areas.
Allowable Release Rate 3.42 cfs Total of 100-year release rate for entire west side.
Historic Flowrates
HISTORIC VS. DEVELOPED FLOWRATES
1204-004
Morningstar/Block 23
Fort Collins, Colorado
Calculation of Release Rate
Q2
Q100
Q100
Q2
Developed Flowrates
Date:11/04/20
Pond No.:
A1
100-yr WQCV Required 2,035 ft3
1.00 Planter Volume 690 ft3
1.75 acres WQCV-Planters 1,345 ft3
14.64 cfs Quantity Detention 817 ft3
Volume Less Planters 2162 ft3
Volume Less Planters 0.050 ac-ft
Time Time
Ft.Collins
100-yr
Intensity
Q100
Inflow
(Runoff)
Volume
Outflow
(Release)
Volume
Storage
Detention
Volume
(mins)(secs)(in/hr)(cfs)(ft3)(ft3)(ft3)
5 300 9.95 17.4 5209 4392 817
10 600 7.72 13.5 8083 8784 -701
15 900 6.52 11.4 10240 13176 -2936
20 1200 5.60 9.8 11726 17568 -5842
25 1500 4.98 8.7 13035 21960 -8925
30 1800 4.52 7.9 14197 26352 -12155
35 2100 4.08 7.1 14951 30744 -15793
40 2400 3.74 6.5 15663 35136 -19473
45 2700 3.46 6.0 16302 39528 -23226
50 3000 3.23 5.6 16909 43920 -27011
55 3300 3.03 5.3 17448 48312 -30864
60 3600 2.86 5.0 17967 52704 -34737
65 3900 2.72 4.7 18511 57096 -38585
70 4200 2.59 4.5 18982 61488 -42506
75 4500 2.48 4.3 19474 65880 -46406
80 4800 2.38 4.2 19935 70272 -50337
85 5100 2.29 4.0 20380 74664 -54284
90 5400 2.21 3.9 20825 79056 -58231
95 5700 2.13 3.7 21186 83448 -62262
100 6000 2.06 3.6 21568 87840 -66272
105 6300 2.00 3.5 21987 92232 -70245
110 6600 1.94 3.4 22343 96624 -74281
115 6900 1.89 3.3 22757 101016 -78259
120 7200 1.84 3.2 23118 105408 -82290
Detention Pond Calculation | FAA Method
Project:
Project Location:
Calculations By:
Morningstar/Block 23
Fort Collins, Colorado
F. Wegert
East Vault (Stormtech Chambers)
Area (A)=
Max Release Rate =
Developed "C" =
Input Variables Results
Design Point Required Detention Volume
Design Storm
P:\1204-004\Drainage\Detention\1204-004_Detention_East.xlsm\
Project:
Chamber Model - SC-740
Units -Imperial
Number of chambers -30
Voids in the stone (porosity) - 30 %
Base of STONE Elevation -100.00 ft
Amount of Stone Above Chambers - 12 in
Amount of Stone Below Chambers -9 in
Area of system -1208 sf Min. Area -
Height of
System
Incremental Single
Chamber
Incremental
Total Chamber
Incremental
Stone
Incremental Ch
& St
Cumulative
Chamber Elevation
(inches)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(feet)
51 0.00 0.00 30.20 30.20 2505.17 104.25
50 0.00 0.00 30.20 30.20 2474.97 104.17
49 0.00 0.00 30.20 30.20 2444.77 104.08
48 0.00 0.00 30.20 30.20 2414.57 104.00
47 0.00 0.00 30.20 30.20 2384.37 103.92
46 0.00 0.00 30.20 30.20 2354.17 103.83
45 0.00 0.00 30.20 30.20 2323.97 103.75
44 0.00 0.00 30.20 30.20 2293.77 103.67
43 0.00 0.00 30.20 30.20 2263.57 103.58
42 0.00 0.00 30.20 30.20 2233.37 103.50
41 0.00 0.00 30.20 30.20 2203.17 103.42
40 0.00 0.00 30.20 30.20 2172.97 103.33
39 0.05 1.65 29.71 31.35 2142.77 103.25
38 0.16 4.89 28.73 33.62 2111.41 103.17
37 0.28 8.46 27.66 36.12 2077.79 103.08
36 0.60 18.12 24.76 42.88 2041.67 103.00
35 0.80 24.05 22.98 47.04 1998.79 102.92
34 0.95 28.52 21.64 50.16 1951.75 102.83
33 1.07 32.24 20.53 52.76 1901.59 102.75
32 1.18 35.41 19.58 54.99 1848.82 102.67
31 1.27 37.97 18.81 56.78 1793.83 102.58
30 1.36 40.65 18.00 58.66 1737.05 102.50
29 1.45 43.62 17.11 60.74 1678.40 102.42
28 1.52 45.74 16.48 62.22 1617.66 102.33
27 1.58 47.47 15.96 63.43 1555.44 102.25
26 1.64 49.27 15.42 64.69 1492.01 102.17
25 1.70 50.99 14.90 65.89 1427.33 102.08
24 1.75 52.59 14.42 67.01 1361.44 102.00
23 1.80 54.08 13.97 68.06 1294.42 101.92
22 1.85 55.65 13.51 69.15 1226.37 101.83
21 1.89 56.79 13.16 69.95 1157.21 101.75
20 1.93 58.02 12.79 70.81 1087.26 101.67
19 1.97 59.25 12.43 71.67 1016.44 101.58
18 2.01 60.30 12.11 72.41 944.77 101.50
17 2.04 61.35 11.80 73.14 872.36 101.42
16 2.07 62.25 11.53 73.77 799.21 101.33
15 2.10 63.15 11.26 74.40 725.44 101.25
14 2.13 63.95 11.01 74.97 651.04 101.17
13 2.15 64.62 10.82 75.43 576.07 101.08
12 2.18 65.31 10.61 75.92 500.64 101.00
11 2.20 65.95 10.41 76.37 424.72 100.92
10 2.21 66.22 10.33 76.55 348.35 100.83
9 0.00 0.00 30.20 30.20 271.80 100.75
8 0.00 0.00 30.20 30.20 241.60 100.67
7 0.00 0.00 30.20 30.20 211.40 100.58
6 0.00 0.00 30.20 30.20 181.20 100.50
5 0.00 0.00 30.20 30.20 151.00 100.42
4 0.00 0.00 30.20 30.20 120.80 100.33
3 0.00 0.00 30.20 30.20 90.60 100.25
2 0.00 0.00 30.20 30.20 60.40 100.17
1 0.00 0.00 30.20 30.20 30.20 100.08
StormTech SC-740 Cumulative Storage Volumes
1014 sf min. area
Include Perimeter Stone in Calculations
Click Here for Metric
Date:11/04/20
Pond No.:
A1
100-yr WQCV 0 ft3
1.00 Quantity Detention 1384 ft3
0.74 acres Total Volume 1384 ft3
3.39 cfs Total Volume 0.032 ac-ft
Time Time
Ft.Collins
100-yr
Intensity
Q100
Inflow
(Runoff)
Volume
Outflow
(Release)
Volume
Storage
Detention
Volume
(mins)(secs)(in/hr)(cfs)(ft3)(ft3)(ft3)
5 300 9.95 7.3 2203 1017 1186
10 600 7.72 5.7 3418 2034 1384
15 900 6.52 4.8 4331 3051 1280
20 1200 5.60 4.1 4959 4068 891
25 1500 4.98 3.7 5513 5085 428
30 1800 4.52 3.3 6004 6102 -98
35 2100 4.08 3.0 6323 7119 -796
40 2400 3.74 2.8 6624 8136 -1512
45 2700 3.46 2.6 6894 9153 -2259
50 3000 3.23 2.4 7151 10170 -3019
55 3300 3.03 2.2 7379 11187 -3808
60 3600 2.86 2.1 7598 12204 -4606
65 3900 2.72 2.0 7829 13221 -5392
70 4200 2.59 1.9 8028 14238 -6210
75 4500 2.48 1.8 8236 15255 -7019
80 4800 2.38 1.8 8431 16272 -7841
85 5100 2.29 1.7 8619 17289 -8670
90 5400 2.21 1.6 8807 18306 -9499
95 5700 2.13 1.6 8960 19323 -10363
100 6000 2.06 1.5 9122 20340 -11218
105 6300 2.00 1.5 9299 21357 -12058
110 6600 1.94 1.4 9449 22374 -12925
115 6900 1.89 1.4 9624 23391 -13767
120 7200 1.84 1.4 9777 24408 -14631
Input Variables Results
Design Point Required Detention Volume
Design Storm
Detention Pond Calculation | FAA Method
Project:
Project Location:
Calculations By:
Morningstar/Block 23
Fort Collins, Colorado
F. Wegert
West Detention Vault
Developed "C" =
Area (A)=
Max Release Rate =
P:\1204-004\Drainage\Detention\1204-004_Detention_West.xlsm\
Project:
Date:
4975.19 1,384 ft3
4977.30 1,163 ft3
4978.75 2,037 ft3
1.08 ft 4977.67
Maximum
Elevation
Minimum
Elevation cu. ft.acre ft cu. ft.acre ft
4975.19 N/A 0.0 0 0.0 0.00 0.0 0.00
4975.25 4975.19 68.6 0.1 2.1 0.00 2.1 0.00
4975.50 4975.25 596.2 0.3 83.1 0.00 85.2 0.00
4975.75 4975.50 596.9 0.3 149.1 0.00 234.3 0.01
4976.00 4975.75 597.6 0.3 149.3 0.00 383.6 0.01
4976.25 4976.00 598.2 0.3 149.5 0.00 533.1 0.01
4976.50 4976.25 598.9 0.3 149.6 0.00 682.7 0.02
4976.75 4976.50 599.6 0.3 149.8 0.00 832.5 0.02
4977.00 4976.75 600.3 0.3 150.0 0.00 982.5 0.02
4977.25 4977.00 601.0 0.3 150.2 0.00 1,132.7 0.03
4977.50 4977.25 601.7 0.3 150.3 0.00 1,283.0 0.03
4977.75 4977.50 602.4 0.3 150.5 0.00 1,433.5 0.03
4978.00 4977.75 603.1 0.3 150.7 0.00 1,584.2 0.04
4978.25 4978.00 603.7 0.3 150.8 0.00 1,735.1 0.04
4978.50 4978.25 604.4 0.3 151.0 0.00 1,886.1 0.04
4978.75 4978.50 604.9 0.3 151.2 0.00 2,037.2 0.05
Freeboard:
Design Volume:
Volume at Grate:
Project Number:
Project Location:
Calculations By:
Pond No.:
Outlet Elevation:
Grate Elevation:
Volume at Crest:
West Detention Vault Stage Storage Curve
Contour Contour
Surface Area
(ft2)
Depth
Incremental Volume Cummalitive Volume
Pond Stage Storage Curve
1204-004
Fort Collins
F. Wegert
Detention Vault (West)
Elev at Design Volume:
Morningstar/Block 23
11/4/2020
Pond Outlet and Volume Data
Crest of Pond Elev.:
11/2/2020 4:45 PM P:\1204-004\Drainage\Detention\Stage Storage\
1204-004_West Pond_Stage-Storage.xlsx\Pond
Project Number :
Project Name :
Project Location :
Pond No :Calc. By:F. Wegert
Orifice Dia (in):8 11/16
Orifice Area (sf):0.4116
Orifice invert (ft):4975.19
Orifice Coefficient:0.65
Elevation Stage (ft)Velocity (ft/s)Flow Rate (cfs)Comments
4975.19 0.00 0.00 0.00
4975.25 0.06 1.28 0.53
4975.50 0.31 2.90 1.19
4975.75 0.56 3.90 1.61
4976.00 0.81 4.69 1.93
4976.25 1.06 5.37 2.21
4976.50 1.31 5.97 2.46
4976.75 1.56 6.51 2.68
4977.00 1.81 7.01 2.89
4977.25 2.06 7.48 3.08
4977.50 2.31 7.92 3.26
4977.67 2.48 8.21 3.38 <-100 Year Elev.
4977.75 2.56 8.34 3.43
4978.00 2.81 8.74 3.60
4978.25 3.06 9.12 3.75
4978.50 3.31 9.49 3.90
4978.75 3.56 9.84 4.05
4979.00 3.81 10.18 4.19
4979.25 4.06 10.51 4.32
4979.50 4.31 10.82 4.46
4979.75 4.56 11.13 4.58
4980.00 4.81 11.43 4.71
4980.25 5.06 11.73 4.83
ORIFICE RATING CURVE
Orifice Rating Curve
1204-004
Morningstar / Block 23
Fort Collins, Colorado
West Detention Vault
Orifice Design Data
Date:03/17/20
Total
Required
WQ Vol.
InFlow,
WQ
Individual
Chamber
Release
Ratea
Individual
Chamber
Volumeb
Individual
Installed
Chamber
Volumec
Min.
Release
Ratee
Required
Chamber
Volume by
FAA
Method
Provided
Release
Ratee
Provided
Chamber
Volumef
Total
Installed
Chamber
Volumeg
(cf)(cfs)(cfs)(cfs)(cfs)(cfs)(cf)(cfs)(cf)(cf)
1 1250 2.3 SC-740 0.024 45.90 74.90 17 0.40 941 13 17 0.40 780 1273
Morningstar/Block 23
Fort Collins, Colorado
F. Wegert
Stormtech Chambers (East Side)
Chamber Configuration Water Quality Summary
Project:
Project Location:
Calculations By:
Description.:
g. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required WQCV.
f. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume.
e. Release rate per chamber times number of chambers.
d. Number of chambers required to provide full WQCV within total installed system, including aggregate.
c. Volume includes chamber and void spaces (40%) in surrounding aggregate, per chamber unit.
b. Volume within chamber only, not accounting for void spaces in surrounding aggregate.
a. Release rate per chamber, limited by flow through geotextile with accumulated sediment.
Vault
ID
Chamber
Type
Min. No. of
Chambersd
Number of
Chambers
per FAA
Provided
Number of
Chambers
Note: "Chamber Volume" refers to the open volume within the vaults. "Installed Chamber Volume" refers to the total volume provided, including the surrounding aggregates.
3/15/2021 P:\1204-004\Drainage\LID\1204-004_Chamber Summary.xlsx
Chamber Dimensions SC-160LP SC-310 SC-740 3500
Width (in)25 34.00 51.00 77.00
Length (in)85.4 85.40 85.40 45.00
Height (in)12 16.00 30.00 90.00
Floor Area (sf)14.83 20.16 30.25 24.06
Chamber Volume (cf)6.85 14.70 45.90 109.90
Chamber/Aggregate Volume (cf) (9" stone base)15.00 31.00 74.90 178.90
Chamber Flow Rate Conversion (gpm/sf to cfs)
0.35 gpm/sf
7.48052 gal
0.1336805 cf
0.002228 cfs
**Flow rate based on 1/2 of Nov 07 QMAX in Figure 17 of UNH Testing Report
SC-160LP SC-310 SC-740 3500
Flow Rate/chamber (cfs)0.0115617 0.0157239 0.023586 0.018764
Chamber Flow Rate
StormTech Chamber Data
Flow Rate**
1 cf =
1 gallon =
1 GPM =
P:\1204-004\Drainage\LID\1204-004_Chamber Summary.xlsx
Date:11/04/20
Pond No.:
A1
WQ
1.00
1.45 acres Quantity Detention 941 ft3
0.42 cfs
Time Time
Ft.Collins
WQ
Intensity
QWQ
Inflow
(Runoff)
Volume
Outflow
(Release)
Volume
Storage
Detention
Volume
(mins)(secs)(in/hr)(cfs)(ft3)(ft3)(ft3)
5 300 1.43 2.1 620 126 494
10 600 1.11 1.6 961 252 709
15 900 0.94 1.4 1220 378 842
20 1200 0.81 1.2 1401 504 897
25 1500 0.72 1.0 1555 630 925
30 1800 0.65 0.9 1697 756 941
35 2100 0.59 0.8 1781 882 899
40 2400 0.54 0.8 1862 1008 854
45 2700 0.50 0.7 1938 1134 804
50 3000 0.46 0.7 2001 1260 741
55 3300 0.44 0.6 2081 1386 695
60 3600 0.41 0.6 2140 1512 628
65 3900 0.39 0.6 2177 1638 539
70 4200 0.37 0.5 2223 1764 459
75 4500 0.35 0.5 2251 1890 361
80 4800 0.33 0.5 2297 2016 281
85 5100 0.32 0.5 2329 2142 187
90 5400 0.31 0.4 2388 2268 120
95 5700 0.29 0.4 2397 2394 3
100 6000 0.28 0.4 2436 2520 -84
105 6300 0.27 0.4 2466 2646 -180
110 6600 0.26 0.4 2488 2772 -284
115 6900 0.26 0.4 2551 2898 -347
120 7200 0.25 0.4 2558 3024 -466
Input Variables Results
Design Point Required Detention Volume
Design Storm
Detention Pond Calculation | FAA Method
Project:
Project Location:
Calculations By:
Morningstar/Block 23
Fort Collins, Colorado
F. Wegert
Stormtech Chambers Infiltration Rate
Area (A)=
Max Release Rate =
Developed "C" =
P:\1204-004\Drainage\LID\1204-004_FAA_Chambers.xlsx\
Project:
Calc. By:
Date:
1.745 <-- INPUT from impervious calcs
90.00 <-- INPUT from impervious calcs
0.9000 <-- CALCULATED
12 hours <-- from UDFCD Vol. 3 Table 3-2
0.8 <-- from UDFCD Vol. 3 Table 3-2
0.321 <-- UDFCD Vol. 3 Equation 3-1
0.047 <-- UDFCD Vol. 3 Equation 3-3
2,035 <-- UDFCD Vol. 3 Equation 3-3
Morningstar/Block 23
F. Wegert
November 4, 2020
WATER QUALITY DESIGN CALCULATIONS
East Parcel
Required Storage & Outlet Works
Basin Area =
Basin Percent Imperviousness =
Basin Imperviousness Ratio =
WQCV (watershed inches) =
WQCV (ac-ft) =
WQCV (ft3) =
Drain Time Coefficient =
Drain Time =
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1.Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =90.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i =0.900
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV =0.32 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area)Area =76,011 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =2,035 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =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 =0.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin =1368 sq ft
D) Actual Flat Surface Area AActual =785 sq ft ACTUAL FLAT AREA < MINIMUM FLAT AREA
E) Area at Design Depth (Top Surface Area)ATop =785 sq ft
F) Rain Garden Total Volume VT=785 cu ft TOTAL VOLUME < DESIGN VOLUME
(VT= ((ATop + AActual) / 2) * Depth)
3.Growing Media
18" thick layer of bioretention sand media over 4" thick layer of pea gravel
over 8" thick layer of CDOT No. 4 aggregate
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 =1.8 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =2,035 cu ft
iii) Orifice Diameter, 3/8" Minimum DO =1 1/16 in
Design Procedure Form: Rain Garden (RG)
Frederick Wegert
Northern Engineering
February 10, 2021
Morningstar/Block 23
Courtyard Planters - East Building
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.03_Planters-East.xlsm, RG 2/10/2021, 8:58 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5.Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B
GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW
THE LINER IF THE SUBGRADE IS ANGULAR
6.Inlet / Outlet Control
A) Inlet Control
7.Vegetation
8.Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Frederick Wegert
Northern Engineering
February 10, 2021
Morningstar/Block 23
Courtyard Planters - East Building
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
UD-BMP_v3.03_Planters-East.xlsm, RG 2/10/2021, 8:58 AM
Project:
Calc. By:
Date:
0.612 <-- INPUT from impervious calcs
100.00 <-- INPUT from impervious calcs
1.0000 <-- CALCULATED
12 hours <-- from UDFCD Vol. 3 Table 3-2
0.8 <-- from UDFCD Vol. 3 Table 3-2
0.400 <-- UDFCD Vol. 3 Equation 3-1
0.024 <-- UDFCD Vol. 3 Equation 3-3
1,066 <-- UDFCD Vol. 3 Equation 3-3
Morningstar/Block 23
F. Wegert
November 4, 2020
WATER QUALITY DESIGN CALCULATIONS
West Parcel
Required Storage & Outlet Works
Basin Area =
Basin Percent Imperviousness =
Basin Imperviousness Ratio =
WQCV (watershed inches) =
WQCV (ac-ft) =
WQCV (ft3) =
Drain Time Coefficient =
Drain Time =
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1.Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =100.0 %
(100% if all paved and roofed areas upstream of sand filter)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i =1.000
C) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV =0.40 watershed inches
WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including sand filter area)Area =26,662 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft
VWQCV = WQCV / 12 * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =1,066 cu ft
(Only if a different WQCV Design Volume is desired)
2.Basin Geometry
A) WQCV Depth DWQCV =2.0 ft
B) Sand Filter Side Slopes (Horizontal distance per unit vertical, Z =0.00 ft / ft
4:1 or flatter preferred). Use "0" if sand filter has vertical walls.
C) Minimum Filter Area (Flat Surface Area)AMin =333 sq ft
D) Actual Filter Area AActual =566 sq ft
E) Volume Provided VT =1215 cu ft
3.Filter Material
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 =1.8 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =1,066 cu ft
iii) Orifice Diameter, 3/8" Minimum DO =3/4 in
Morningstar/Block 23
Sand Filter Vault - West Building/Parking Garage
Design Procedure Form: Sand Filter (SF)
Frederick S. Wegert
Northern Engineering
December 15, 2020
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" CDOT Class B or C Filter Material
Other (Explain):
YES
NO
UD-BMP_v3.03_Sand Filter_West.xlsm, SF 12/15/2020, 8:34 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5.Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
PROVIDE A 30 MIL (MIN) PVC GEOMEMBRANE PER TABLE
SF-4 WITH SEPARATOR FABRIC (PER TABLE SF-3) ABOVE IT.
PROVIDE SEPARATOR FABRIC BELOW THE GEOMEMBRANE
AS WELL IF SUBGRADE IS ANGULAR OR COULD OTHERWISE
PUNCTURE THE GEOMEMBRANE.
6.Inlet / Outlet Works
A) Describe the type of energy dissipation at inlet points and means of
conveying flows in excess of the WQCV through the outlet
Notes:
Design Procedure Form: Sand Filter (SF)
Frederick S. Wegert
Northern Engineering
December 15, 2020
Morningstar/Block 23
Sand Filter Vault - West Building/Parking Garage
Choose One
YES NO
UD-BMP_v3.03_Sand Filter_West.xlsm, SF 12/15/2020, 8:34 AM
Project:
Date:
4976.64 1,066 ft3
4978.65 1,125 ft3
4978.75 1,184 ft3
0.20 ft 4978.55
Maximum
Elevation
Minimum
Elevation cu. ft.acre ft cu. ft.acre ft
4976.64 N/A 0.0 0 0.0 0.00 0.0 0.00
4976.75 4976.64 566.8 0.1 31.2 0.00 31.2 0.00
4977.00 4976.75 569.2 0.3 142.0 0.00 173.2 0.00
4977.25 4977.00 571.6 0.3 142.6 0.00 315.8 0.01
4977.50 4977.25 574.0 0.3 143.2 0.00 459.0 0.01
4977.75 4977.50 576.4 0.3 143.8 0.00 602.8 0.01
4978.00 4977.75 578.8 0.3 144.4 0.00 747.2 0.02
4978.25 4978.00 581.2 0.3 145.0 0.00 892.2 0.02
4978.50 4978.25 583.6 0.3 145.6 0.00 1,037.8 0.02
4978.75 4978.50 585.3 0.3 146.1 0.00 1,183.9 0.03
Freeboard:
WQ Volume:
Volume at Overflow:
Project Number:
Project Location:
Calculations By:
Pond No.:
Top of Sand Elev.:
Overflow Elevation:
Volume at Crest:
West Sand Filter Vault Stage Storage Curve
Contour Contour
Surface Area
(ft2)
Depth
Incremental Volume Cummalitive Volume
Pond Stage Storage Curve
1204-004
Fort Collins
F. Wegert
Sand Filter Vault
Elev at WQ Volume:
Morningstar/Block 23
12/15/2020
Pond Outlet and Volume Data
Crest of Pond Elev.:
12/15/2020 8:52 AM P:\1204-004\Drainage\Detention\Stage Storage\
1204-004_West Sand Filter_Stage-Storage.xlsx\Pond
Project Number :
Project Name :
Project Location :
Pond No :Calc. By:
Q=3.3LH 1.5
Length (L)=21.00 FT
Crest Elevation =4978.65 FT
Depth Above Crest
(ft)
Elevation
(ft)
Flow
(cfs)
0.00 4978.65 0.00
0.10 4978.75 2.19
0.20 4978.85 6.20 Q100
0.30 4978.95 11.39
0.40 4979.05 17.53
0.50 4979.15 24.50
0.60 4979.25 32.21
0.70 4979.35 40.59
0.80 4979.45 49.59
0.90 4979.55 59.17
1.00 4979.65 69.30
Q100 = 6.1 CFS
Input Parameters:
Depth vs. Flow:
Sand Filter Vault
SHARP-CRESTED WEIR
This equation can be used to derive the stage-discharge relationship for a sharp crested weir where the depth of flow
is small compared to the length of weir. Reference 1) Hydrologic Analysis and Design, Richard H McCuen, Prentice
Hall, 1989. Pg.549.
* where Q is flow rate in CFS
* where L is the crest length of the weir (FT)
* where H is the height of flow over the crest (FT)
Governing Equations:
1204-004
Morningstar / Block 23
Fort Collins, Colorado
F. Wegert
Appendix D
Erosion Control Report
Final Drainage Report March 17, 2021
Morningstar/Block 23 Erosion Control Report
Erosion Control Report
A comprehensive Erosion and Sediment Control Plan (along with associated details) has been
included with the final construction drawings. It should be noted, however, that any such
Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging
and/or phasing of the BMPs depicted, and additional or different BMPs from those included
may be necessary during construction, or as required by the authorities having jurisdiction.
It shall be the responsibility of the Contractor to ensure erosion control measures are properly
maintained and followed. The Erosion and Sediment Control Plan is intended to be a living
document, constantly adapting to site conditions and needs. The Contractor shall update the
location of BMPs as they are installed, removed or modified in conjunction with construction
activities. It is imperative to appropriately reflect the current site conditions at all times.
The Erosion and Sediment Control Plan shall address both temporary measures to be
implemented during construction, as well as permanent erosion control protection. Best
Management Practices from the Volume 3, Chapter 7 – Construction BMPs will be utilized.
Measures may include, but are not limited to, silt fencing and/or wattles along the disturbed
perimeter, gutter protection in the adjacent roadways and inlet protection at existing and
proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up
procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be
provided by the Contractor.
Grading and Erosion Control Notes can be found on Sheet CS2 of the Utility Plans. The Final
Utility Plans will also contain a full-size Erosion Control Plan as well as a separate sheet
dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets,
the Contractor shall be aware of, and adhere to, the applicable requirements outlined in any
existing Development Agreement(s) of record, as well as the Development Agreement, to be
recorded prior to issuance of the Development Construction Permit. Also, the Site Contractor
for this project may be required to secure a Stormwater Construction General Permit from the
Colorado Department of Public Health and Environment (CDPHE), Water Quality Control
Division – Stormwater Program, before commencing any earth disturbing activities. Prior to
securing said permit, the Site Contractor shall develop a comprehensive Storm Water
Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will
further describe and document the ongoing activities, inspections, and maintenance of
construction BMPs.
Appendix E
USDA Soils Report
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Larimer County
Area, Colorado
Block 23
Natural
Resources
Conservation
Service
September 25, 2019
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface....................................................................................................................2
How Soil Surveys Are Made..................................................................................5
Soil Map..................................................................................................................8
Soil Map................................................................................................................9
Legend................................................................................................................10
Map Unit Legend................................................................................................11
Map Unit Descriptions.........................................................................................11
Larimer County Area, Colorado......................................................................13
81—Paoli fine sandy loam, 0 to 1 percent slopes.......................................13
Soil Information for All Uses...............................................................................15
Soil Properties and Qualities..............................................................................15
Soil Erosion Factors........................................................................................15
K Factor, Whole Soil....................................................................................15
Soil Qualities and Features.............................................................................18
Hydrologic Soil Group.................................................................................18
References............................................................................................................23
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
Custom Soil Resource Report
6
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
8
9
Custom Soil Resource Report
Soil Map
449334044933704493400449343044934604493490449334044933704493400449343044934604493490493270 493300 493330 493360 493390 493420 493450 493480 493510 493540
493270 493300 493330 493360 493390 493420 493450 493480 493510 493540
40° 35' 32'' N 105° 4' 46'' W40° 35' 32'' N105° 4' 34'' W40° 35' 26'' N
105° 4' 46'' W40° 35' 26'' N
105° 4' 34'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,270 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 Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
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 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
10
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
81 Paoli fine sandy loam, 0 to 1
percent slopes
5.7 100.0%
Totals for Area of Interest 5.7 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
Custom Soil Resource Report
11
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
Custom Soil Resource Report
12
Larimer County Area, Colorado
81—Paoli fine sandy loam, 0 to 1 percent slopes
Map Unit Setting
National map unit symbol: jpxx
Elevation: 4,800 to 5,600 feet
Mean annual precipitation: 13 to 15 inches
Mean annual air temperature: 48 to 50 degrees F
Frost-free period: 135 to 150 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Paoli and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Paoli
Setting
Landform: Stream terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Alluvium
Typical profile
H1 - 0 to 30 inches: fine sandy loam
H2 - 30 to 60 inches: fine sandy loam, sandy loam, loamy sand
H2 - 30 to 60 inches:
H2 - 30 to 60 inches:
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Very low
Capacity of the most limiting layer to transmit water (Ksat): High (2.00 to 6.00
in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0
mmhos/cm)
Available water storage in profile: Very high (about 16.5 inches)
Interpretive groups
Land capability classification (irrigated): 1
Land capability classification (nonirrigated): 3c
Hydrologic Soil Group: A
Ecological site: Overflow (R067BY036CO)
Hydric soil rating: No
Custom Soil Resource Report
13
Minor Components
Caruso
Percent of map unit: 6 percent
Hydric soil rating: No
Table mountain
Percent of map unit: 6 percent
Hydric soil rating: No
Fluvaquentic haplustolls
Percent of map unit: 3 percent
Landform: Terraces
Hydric soil rating: Yes
Custom Soil Resource Report
14
Soil Information for All Uses
Soil Properties and Qualities
The Soil Properties and Qualities section includes various soil properties and
qualities displayed as thematic maps with a summary table for the soil map units in
the selected area of interest. A single value or rating for each map unit is generated
by aggregating the interpretive ratings of individual map unit components. This
aggregation process is defined for each property or quality.
Soil Erosion Factors
Soil Erosion Factors are soil properties and interpretations used in evaluating the
soil for potential erosion. Example soil erosion factors can include K factor for the
whole soil or on a rock free basis, T factor, wind erodibility group and wind erodibility
index.
K Factor, Whole Soil
Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by
water. Factor K is one of six factors used in the Universal Soil Loss Equation
(USLE) and the Revised Universal Soil Loss Equation (RUSLE) to predict the
average annual rate of soil loss by sheet and rill erosion in tons per acre per year.
The estimates are based primarily on percentage of silt, sand, and organic matter
and on soil structure and saturated hydraulic conductivity (Ksat). Values of K range
from 0.02 to 0.69. Other factors being equal, the higher the value, the more
susceptible the soil is to sheet and rill erosion by water.
"Erosion factor Kw (whole soil)" indicates the erodibility of the whole soil. The
estimates are modified by the presence of rock fragments.
15
16
Custom Soil Resource Report
Map—K Factor, Whole Soil
449334044933704493400449343044934604493490449334044933704493400449343044934604493490493270 493300 493330 493360 493390 493420 493450 493480 493510 493540
493270 493300 493330 493360 493390 493420 493450 493480 493510 493540
40° 35' 32'' N 105° 4' 46'' W40° 35' 32'' N105° 4' 34'' W40° 35' 26'' N
105° 4' 46'' W40° 35' 26'' N
105° 4' 34'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,270 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
.02
.05
.10
.15
.17
.20
.24
.28
.32
.37
.43
.49
.55
.64
Not rated or not available
Soil Rating Lines
.02
.05
.10
.15
.17
.20
.24
.28
.32
.37
.43
.49
.55
.64
Not rated or not available
Soil Rating Points
.02
.05
.10
.15
.17
.20
.24
.28
.32
.37
.43
.49
.55
.64
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 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
17
Table—K Factor, Whole Soil
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
81 Paoli fine sandy loam, 0
to 1 percent slopes
.15 5.7 100.0%
Totals for Area of Interest 5.7 100.0%
Rating Options—K Factor, Whole Soil
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Layer Options (Horizon Aggregation Method): Surface Layer (Not applicable)
Soil Qualities and Features
Soil qualities are behavior and performance attributes that are not directly
measured, but are inferred from observations of dynamic conditions and from soil
properties. Example soil qualities include natural drainage, and frost action. Soil
features are attributes that are not directly part of the soil. Example soil features
include slope and depth to restrictive layer. These features can greatly impact the
use and management of the soil.
Hydrologic Soil Group
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.
Custom Soil Resource Report
18
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.
Custom Soil Resource Report
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20
Custom Soil Resource Report
Map—Hydrologic Soil Group
449334044933704493400449343044934604493490449334044933704493400449343044934604493490493270 493300 493330 493360 493390 493420 493450 493480 493510 493540
493270 493300 493330 493360 493390 493420 493450 493480 493510 493540
40° 35' 32'' N 105° 4' 46'' W40° 35' 32'' N105° 4' 34'' W40° 35' 26'' N
105° 4' 46'' W40° 35' 26'' N
105° 4' 34'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,270 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 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
21
Table—Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
81 Paoli fine sandy loam, 0
to 1 percent slopes
A 5.7 100.0%
Totals for Area of Interest 5.7 100.0%
Rating Options—Hydrologic Soil Group
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Custom Soil Resource Report
22
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/national/soils/?cid=nrcs142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuse/rangepasture/?cid=stelprdb1043084
23
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/soils/scientists/?cid=nrcs142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf
Custom Soil Resource Report
24
Appendix F
FEMA Firmette
Map Pocket
DR1 –Drainage Exhibit
UDUDUDUDUDFO
FOUD FO FO FO FO FO FO FOFOFOFOFOS FUDUDUDFDC
16" WEEEE E E E E E
R R
VAULT
F.O.
F.O.
G
VAULT
F.O.
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
F.O.CCCHERRY ST
N COLLEGE AVEMAPLE STN MASON STOLD TOWN FLATS LLC
310 N MASON ST
FORT COLLINS, CO 80524
10
10
10
a1
a3
a2
b2
w2
w4
PARKING
GARAGE
SENIOR LIVING
BUILDING UNION PACIFIC RAILROADBURLINGTON NORTHERN RAILROADPROPOSED OUTLET
STRUCTURE
PROPOSED
INLET
PROPOSED
INLET
PROPOSED RAIN GARDEN TYPE
PLANTER WITH UNDER DRAIN
AND IMPERMEABLE LINER
CONNECT TO EXISTING
STORM DRAIN
PROPOSED RAIN GARDEN TYPE
PLANTER WITH UNDER DRAIN
AND IMPERMEABLE LINER
PROPOSED RAIN GARDEN TYPE
PLANTER WITH UNDER DRAIN
AND IMPERMEABLE LINER
PROPOSED
UNDER DRAIN
30 TOTAL STORMTECH CHAMBERS:
ISOLATOR ROWS = 17 CHAMBERS
STANDARD ROWS = 13 CHAMBERS
(SEE NOTE 2.)
EXISTING
INLETS
EXISTING INLET TO
BE REPLACED WITH
A SOLID MH COVER
PROPOSED
STORM DRAIN
PROPOSED
STORM DRAIN
PROPOSED
STORM MANHOLE
PROPOSED
INLET
EXISTING
STORM DRAIN
PROPOSED
INLET
PROPOSED
INLET
PROPOSED
INLET
PROPOSED
INLET
EXISTING
STORM DRAIN
EXISTING
INLET
PROPOSED
STORM DRAIN
PROPOSED 2'
SIDEWALK CHASE
PROPOSED 2'
SIDEWALK CHASE
w3
w1
b1
e5
e1
e3
e2
e4
0.61 ac.
E4
0.31 ac.
E2
0.40 ac.
E1
0.21 ac.
E3
0.29 ac.
A3
0.28 ac.
A2
0.23 ac.
A1
0.09 ac.
B1
0.61 ac.
W2
0.07 ac.
W4
0.16 ac.
B2
0.61 ac.
W3
0.01 ac.
W1
0.01 ac.
E5
0.08 ac.
C1
0.11 ac.
C2
c1
c2
PROPOSED SAND
FILTER VAULT
PROPOSED
DETENTION VAULT
PROPOSED
INLET
PROPOSED UNDERGROUND
VAULT OUTLET STRUCTURE
0.70 ac.
OS1
os1
SheetBLOCK 23 - MORNINGSTARThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETENGINEERNGIEHTRONRNFORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631970.221.4158northernengineering.comof 28
NORTH
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
before you dig.Call
R
DR1 DRAINAGE EXHIBIT28
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
PROPOSED CONTOUR
PROPOSED STORM SEWER
EXISTING CONTOUR
PROPOSED CURB & GUTTER
PROPERTY BOUNDARY
PROPOSED INLET
ADESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
PROPOSED SWALE SECTION
11
NOTES:
1.REFER TO THE FINAL DRAINAGE REPORT FOR BLOCK 23, DATED FEBRUARY 10, 2021
FOR ADDITIONAL INFORMATION.
2.SEE COVER SHEET FOR BENCHMARK AND BASIS OF BEARING.
3.IF NECESSARY, STANDARD STORMTECH CHAMBERS CAN BE CONVERTED INTO AN
ISOLATOR ROW TO FACILITATE CONSTRUCTION. AT MINIMUM, THERE MUST BE 18
CHAMBERS IN ISOLATOR ROWS AND A TOTAL OF 30 CHAMBERS. CONTRACTOR TO
COORDINATE STORMTECH CHAMBER LAYOUT AND DESIGN WITH MANUFACTURER.
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
C
LEGEND:
DEVELOPED DRAINAGE BASINS
Design
Point Basin ID
Total
Area
(acres)
C2 C100 2-Yr Tc
(min)
100-Yr Tc
(min)
Q2
(cfs)
Q100
(cfs)
a1 A1 0.229 0.62 0.77 6.34 6.34 0.38 1.64
a2 A2 0.285 0.81 1.00 5.00 5.00 0.65 2.83
a3 A3 0.287 0.88 1.00 5.00 5.00 0.71 2.85
b1 B1 0.088 0.64 0.80 5.00 5.00 0.16 0.70
b2 B2 0.161 0.93 1.00 5.00 5.00 0.42 1.60
c1 C1 0.085 0.95 1.00 5.00 5.00 0.23 0.84
c2 C2 0.113 0.95 1.00 5.00 5.00 0.31 1.12
e1 E1 0.398 0.91 1.00 5.48 5.48 1.03 3.96
e2 E2 0.309 0.95 1.00 5.37 5.37 0.84 3.07
e3 E3 0.213 0.95 1.00 5.00 5.00 0.58 2.12
e4 E4 0.615 0.93 1.00 7.82 7.82 1.40 5.28
e5 E5 0.012 0.95 1.00 5.00 5.00 0.03 0.12
w1 W1 0.010 0.15 0.18 7.47 7.47 0.00 0.02
w2 W2 0.612 0.95 1.00 5.00 5.00 1.66 6.09
w3 W3 0.048 0.27 0.34 5.00 5.00 0.04 0.16
w4 W4 0.068 0.10 0.13 7.26 7.26 0.02 0.07
os1 OS1 0.698 0.95 1.00 5.00 5.00 1.89 6.95
COMBINED BASINS
a1 Cherry 0.327 0.61 0.76 7.79 7.79 0.49 2.13
a2 College 0.285 0.81 1.00 5.00 5.00 0.65 2.83
a3 Maple 0.287 0.88 1.00 5.00 5.00 0.71 2.85
b2 Alley 0.823 0.89 1.00 5.00 5.00 2.09 8.19
a1 East 1.745 0.93 1.00 5.00 5.00 4.64 17.36
w2 West 0.738 0.82 1.00 5.26 5.26 1.72 7.34
a1 Total 3.532 0.87 1.00 5.00 5.00 8.71 35.14
Block 23 / Morningstar LID Summary
Project Summary
Impervious Area (East Side) 74,028 sf
Impervious Area (West Side) 29,971 sf
Total Impervious Area 103,999 sf
Target Treatment Percentage 75%
Minimum Area to be Treated by LID measures 77,999.25 sf
Planter/Rain Garden (East Side)
Total Rain Garden Treatment Area 12,023 sf
Chamber Isolator Rows
Total Chamber Treatment Area 54,057 sf
Sand Filter
Total Sand Filter Treatment Area 26,306 sf
Total Treatment Area 92,386 sf
Percent Total Project Area Treated 88.8%
DETENTION POND SUMMARY
Pond ID
Required
Detention
Volume (cf)
Required
Water Quality
Volume (cf)
Required Total
Volume (cf)
Design
Detention
Volume (cf)
Design Water
Quality Volume
(cf)
Design Total
Volume (cf)
East Side
Rain Gardens 0 785 785 0 785 785
Stormtech Chambers 817 1250 2067 974 1273 2247
Total (East Side)2852 3032
West Side
Sand Filter Vault 0 1066 1066 0 1215 1215
Detention Vault 1384 0 1384 2037 0 2037
Total (West Side)2450 3252
DETENTION POND SUMMARY TABLE NOTES:
1.CF = CUBIC FEET
2.ISOLATOR ROWS IN STORMTECH CHAMBERS ARE TO PROVIDE WATER QUALITY VOLUME.
3.STANDARD ROWS IN STORMTECH CHAMBERS ARE TO PROVIDE DETENTION VOLUME.
EXISTING DRAINAGE BASINS
Design
Point Basin ID
Total
Area
(acres)
C2 C100 2-Yr Tc
(min)
100-Yr Tc
(min)
Q2
(cfs)
Q100
(cfs)
h-a1 H-A1 0.317 0.71 0.88 6.66 6.66 0.58 2.54
h-a2 H-A2 0.167 0.92 1.00 5.00 5.00 0.44 1.66
h-a3 H-A3 0.113 0.78 0.97 5.00 5.00 0.25 1.10
h-b4 H-B2 0.160 0.95 1.00 5.00 5.00 0.43 1.59
h-a1 H-E1 0.390 0.86 1.00 8.05 8.05 0.81 3.27
h-a3 H-E2 0.424 0.95 1.00 6.18 6.18 1.08 3.95
h-a5 H-E3 0.092 0.86 1.00 5.00 5.00 0.23 0.92
h-e4 H-E4 0.838 0.80 0.99 8.95 8.95 1.57 6.84
h-a1 H-W1 0.028 0.50 0.63 12.48 12.48 0.03 0.13
h-w2 H-W2 0.709 0.50 0.63 11.34 11.34 0.76 3.29
os1 OS1 0.698 0.95 1.00 5.00 5.00 1.89 6.95
COMBINED BASINS
h-b5 HW-Site 0.738 0.50 0.63 11.34 11.34 0.79 3.42
h-b5 HW-Imp 0.738 0.50 0.63 11.34 11.34 0.79 3.42
h-a1 HE-Site 1.745 0.85 1.00 8.27 8.27 3.57 14.62
h-a1 HE-Imp 1.702 0.87 1.00 7.98 7.98 3.64 14.62
h-a1 HE-Per 0.043 0.20 0.25 12.07 12.07 0.02 0.08
h-a1 Total 3.240 0.76 0.95 13.01 13.01 4.85 21.21