HomeMy WebLinkAboutBRICK STONE APARTMENTS ON HARMONY - FDP - FDP170006 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFINAL DRAINAGE REPORT
BRICK STONE APARTMENTS
Fort Collins, Colorado
February 1, 2017
Prepared for:
SEEC Enterprises, LLC
PO Box 680513
Park City, Utah 84068
Prepared by:
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 1229-001
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 absolutely necessary, we recommend double-sided printing.
February 1, 2017
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage Report for
Brick Stone Apartments
Dear Staff:
Northern Engineering is pleased to submit this Final Drainage Report for your review. This report
accompanies the Conceptual Review submittal for the proposed Brick Stone Apartments.
This report has been prepared in accordance with the City of Fort Collins Stormwater Criteria
Manual (FCSCM) and the Urban Drainage and Flood Control District (UDFCD) Urban Storm
Drainage Criteria Manual and serves to document the stormwater impacts associated with the
proposed Brick Stone Apartments project. We understand that review by the City of Fort Collins is
to assure general compliance with standardized criteria.
If you should have any questions as you review this report, please feel free to contact us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
Nicholas W. Haws, PE Blaine Mathisen
Vice President Project Engineer
Brick Stone Apartments
Final Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 2
C. Floodplain.......................................................................................................................................... 3
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4
A. Major Basin Description .................................................................................................................... 4
B. Sub-Basin Description ....................................................................................................................... 4
III. DRAINAGE DESIGN CRITERIA ................................................................................... 5
A. Regulations........................................................................................................................................ 5
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 6
D. Hydrological Criteria ......................................................................................................................... 7
E. Hydraulic Criteria .............................................................................................................................. 7
F. Floodplain Regulations Compliance .................................................................................................. 7
G. Modifications of Criteria ................................................................................................................... 7
IV. DRAINAGE FACILITY DESIGN .................................................................................... 7
A. General Concept ............................................................................................................................... 7
B. Specific Details ................................................................................................................................ 10
V. CONCLUSIONS ...................................................................................................... 12
A. Compliance with Standards ............................................................................................................ 12
B. Drainage Concept ............................................................................................................................ 12
References ....................................................................................................................... 14
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations
B.1 – Storm Sewers
B.2 – Inlets
B.3 – Detention Facilities
APPENDIX C – Water Quality Design Computations
APPENDIX D – Erosion Control Report
APPENDIX E – Soils Resource Report
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Final Drainage Report
LIST OF TABLES AND FIGURES:
Figure 1 - Aerial Photograph - Google Earth ............................................................................ 1
Figure 2 - Proposed Site Plan ............................................................................................... 3
Figure 3 - Existing City Floodplain ......................................................................................... 4
MAP POCKET:
C8.00 - Historic Drainage Exhibit
C8.01 - Drainage Exhibit
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Final Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
Figure 1 - Aerial Photograph - Google Earth
2. Brick Stone Apartments project is located in the Northwest Quarter of Section 1,
Township 6 North, Range 69 West of the 6th P.M., City of Fort Collins, County of
Larimer, State of Colorado.
3. The project site is located on the south side of East Harmony Road and just east of
South College Avenue. Brick Stone Apartments will have the address of 201 W.
Harmony Road. The project is currently bordered to the north by East Harmony Road,
south by the Mail Creek Floodway, west by a commercial building, and east by an
assisted living complex.
4. Currently the existing lot remains completely undeveloped however there is currently
stormwater infrastructure associated with the Brick Stone Apartments project on site.
There is a drainage ditch near the western property line (Larimer County Ditch #2)
with a trash rack that the city regularly maintains and cleans out. This ditch conveys
flow from north to south into the Mail Creek Floodway which runs adjacent to the
southern property line. There is also an existing irrigation ditch along the north
property line that conveys flow from East Harmony Road east towards its ultimate
design point at the intersection of Boardwalk Dr. and Harmony Road.
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B. Description of Property
1. Brick Stone Apartments project site is approximately 4.41 net acres. Due to the need
for a turn lane onto the property, additional area will be associated with the Brick
Stone Apartments project along the north property line. However, due to the Mail
Creek Floodway and Larimer County Ditch #2 the project site will not be developing a
decent amount of the southern portion of the project site and all the area associated
with the Larimer County Ditch #2 as well as the area directly west of the Larimer
County Ditch #2. All in all, the overall limits of disturbance is roughly 3.07 acres.
2. Brick Stone Apartments consists of a portion of an existing tract of land. There will be
offsite runoff entering the property. Historically, flow generated between College
Avenue and a low point along the northern property line within Harmony Road enters
the site via curb cut and flows into an existing irrigation ditch. Runoff entering the
existing irrigation ditch is conveyed east. Additional concentrated offsite flows enter
the site through the Larimer County Ditch #2 near the west property line and runs
down a rip-rap embankment until it reaches Mail Creek Floodway.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey, 56.1 percent of the site consists of Altvan-
Satanta loams, which fall into Hydrologic Soil Groups B. The other 43.9 percent of
the site consists of Nunn clay loam, which falls into Hydrologic Soils Group C. A more
precise soils investigation was performed by Terracon Consultants Inc.
4. The proposed development will include the clearing of existing vegetation, nine (9)
trees, removal of an existing wall, and the removal of the irrigation ditch and any
associated infrastructure. The proposed project will include a multifamily building with
associated parking both underground and uncovered. There will be a courtyard at the
center of the building with an emergency access drive leading up to it. There is an
additional emergency access along the west side of the building directly off of East
Harmony Road. Along the south side of the building, there will be sidewalks with
associated landscaping walls in order to maintain reasonable slopes and reduce the
limits of disturbance. Water quality and detention will be provided via two separate
underground Stormtech chamber systems. Both systems will discharge into the Mail
Creek Floodway at reduced release rates. This will be discussed further on in the
report.
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Figure 2 - Proposed Site Plan
5. There are irrigation facilities (Larimer County Ditch #2), erosion buffer zones, and
major drainage ways (Mail Creek Floodway) within the property limits.
6. The project site is within the Harmony Corridor District (H-C). The proposed use is
permitted within this zone district.
C. Floodplain
1. The subject property does not lie within a plottable FEMA floodplain. However,
according to FIRM Panel 08069C1000F for Larimer County, dated December 19th,
2006, this tract lies in an area of minimal flood hazard, Zone X.
2. A portion of the Brick Stone Apartment project does fall within a City of Fort Collins
floodplain (Mail Creek Floodway). Any development within the floodway must obtain a
floodplain use permit, a no-rise certificate and also comply with the safety regulations
of Chapter 10 of City Municipal Code. A portion of this property is located within the
erosion buffer zone for Mail Creek. Construction of a structure is not allowed in an
erosion buffer zone and all nonstructural development must meet the standards of
Section 10-202 of City Municipal Code. Proposed vegetation within the erosion buffer
zone must be non-irrigated native vegetation that enhances the stability of the creek.
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Final Drainage Report 4
Figure 3 - Existing City Floodplain
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. Brick Stone Apartments is within the Mail Creek Drainage Basin. This basin drains
from west to east to the confluence of Mail Creek and Fossil Creek, and ultimately to
Fossil Creek Reservoir.
2. There are no previous drainage studies for the area associated with the Brick Stone
Apartments project site.
B. Sub-Basin Description
1. Brick Stone Apartments historically sheet flows north to south towards Mail Creek.
These historic conditions will be maintained to the best of the engineer’s ability.
Basin H1
Basin H1 is associated with most of the project area (4.30 acres out of 4.41 acres)
and all the runoff is conveyed into Mail Creek. Within Basin H1 there is an existing
drainage ditch (Larimer County Ditch #2) near the western property line that directs
offsite flow via a culvert and rip-rap embankment towards Mail Creek. This offsite flow
will not be disturbed or altered during or after the construction of Brick Stone
Apartments. Basin H1 lies within an erosion buffer zone which is associated with the
Mail Creek Floodway. No structures will be placed within the erosion buffer zone.
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Final Drainage Report 5
Basin OS1
Basin OS1 is associated with the south side of the East Harmony Road right of way
from College Avenue to the private drive aisle located at the northeast corner of the
project site. Historically, the flow associated with this area has entered the site via a
curb cut at a low point along the north property line and then entering an existing
irrigation ditch that runs west to east along the south side of Harmony Road.
However, the Brick Stone Apartments project will be extending the limits of the right
of way to ultimate design all along the north property line, which will require the
removal of the ditch. Brick Stone Apartments will be detaining and treating a portion
of the runoff from Harmony Road. Brick Stone Apartments will be detaining the
equivalent of a local street section but will be providing water quality for all of the flow
north of the project site within Harmony Road. This is discussed further on in the
report.
2. A more detailed description of the projects proposed drainage patterns follows in
Section IV.A.4., below.
3. There is offsite flow associated with Brick Stone Apartments as previously discussed.
A full-size copy of the Historic and Proposed Drainage Exhibit can be found in the
Map Pocket at the end of this report.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the Brick Stone
Apartments project.
B. Four Step Process
The overall stormwater management strategy employed with the Brick Stone Apartments
project 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
Several techniques have been utilized with the proposed development to facilitate the
reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the
current use by implementing multiple Low-Impact Development (LID) strategies including:
Providing as much vegetated open areas as possible along the north, east, west and
south portion of the site to reduce the overall impervious area and to minimize directly
connected impervious areas (MDCIA).
Routing flows, to the extent feasible, through underground Stormtech Isolator Rows for
water quality purposes.
Providing on-site detention to increase time of concentration, promote infiltration and
reduce loads on downstream storm infrastructure.
Routing runoff from the roofs directly into isolator rows.
Brick Stone Apartments will minimize the limits of disturbance to the fullest extent
possible in order to maintain existing drainage patterns.
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It should be noted that 100% of all the water quality is being provided by isolator rows
which is considered an LID feature.
Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with
Slow Release
The efforts taken in Step 1 will facilitate the reduction of runoff and provide the necessary
BMPs required for water quality. Stormwater generated on the western portion of the
project site will remain unaltered and will be free released directly into Mail Creek. Due to
grade constraints and the lack of space along the south side of the multifamily building
Brick Stone Apartments is unable to capture and treat this runoff therefore it will be free
released south towards Mail Creek like it historically has. The remaining portion of the site
will be captured in inlets and roof leaders and routed to underground detention and water
quality facilities. Runoff will be released at a reduced historic 2-year event because of the
non-catchable flow leaving the site.
Step 3 – Stabilize Drainageways
As stated in Section I.B.5, above, there is a major drainageway associated with the project
site. The erosion buffer zone per city of Fort Collins City Flood Risk Map will remain
completely undeveloped and no construction will take place within this zone. The Mail
Creek floodway will also remain completely unaltered. Flow associated with Larimer
County Ditch #2 will also remain unaltered. However, the culvert associated with the
ditch will need to be extended because Harmony Rd. is being constructed to its ultimate
design. By under-utilizing the site and keeping a large area undisturbed, combined with
LID, the likelihood of bed and bank erosion is greatly reduced. Furthermore, this project
will pay a 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 and is not
applicable for this project.
C. Development Criteria Reference and Constraints
1. There are no known drainage studies for the existing property.
2. There is a drainage study for the adjacent lot to the east titled “Final Drainage Report
for Fort Collins Supportive Housing” by S. A. Miro, Inc. dated May 25th, 2007 which
discusses the historic use of the existing irrigation ditch that runs west to east along
East Harmony Road.
3. The subject property is essentially an "in-fill" development project as the property is
surrounded by currently developed properties. As such, several constraints have been
identified during the course of this analysis that will impact the proposed drainage
system including:
Existing elevations along the east, west, and south property lines will be
maintained. Areas along the northern property line will be modified through the
grading of the ultimate design of Harmony Road.
Brick Stone Apartments plans on disturbing as little of the existing grades as
possible.
During the construction of Brick Stone Apartments, Harmony Rd. will also be
extended to its ultimate design along the northern property line. Therefore, the
existing irrigation ditch will be removed and the pipes under the shared access
drive along the east property line will be abandoned.
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Overall drainage patterns of the existing site will be maintained.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
associated with this development. Tabulated data contained in Table RA-7 has been
utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
3. The Rational Formula-based Modified Federal Aviation Administration (FAA)
procedure has been 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.
5. No other assumptions or calculation methods have been used with this development
that are not referenced by current City of Fort Collins criteria.
E. Hydraulic Criteria
1. As previously noted, the subject property historically drains north to south into Mail
Creek. Most of the site, with the exception of Larimer County Ditch #2, drains
stormwater via overland flow.
2. All drainage facilities proposed with the Brick Stone Apartments project are designed
in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and
Flood Control District’s (UDFCD) Urban Storm Drainage Criteria Manual.
3. As stated in Section I.C.1, above, the subject property is located within a City
regulatory floodplain (Mail Creek Floodway).
4. Brick Stone Apartments does not propose to modify any natural drainageways.
F. Floodplain Regulations Compliance
1. As previously mentioned, the project site falls within a City regulatory floodplain (Mail
Creek Floodway). However, all structures are located outside of the City floodplain
and erosion buffer zone.
G. Modifications of Criteria
1. The proposed Brick Stone Apartments development is not requesting any
modifications at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the Brick Stone Apartments drainage design is to maintain
existing drainage patterns and ensure no adverse impacts to any adjacent properties
or existing infrastructure downstream of the site.
2. As previously mentioned, there are off-site flows draining onto the existing property.
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These flows are going to get constrained in the new Harmony Road curb and gutter.
Brick Stone Apartments anticipates capturing, detaining, and treating the local road
equivalent of the southern portion of Harmony Road all along the northern property
boundary. Additionally, Brick Stone Apartments will also be providing water quality for
the entire section of Harmony Road but will not be detaining the area outside the
local road equivalent. This is discussed further below in the explanation of Basin
OS.1.
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. Brick Stone Apartments has been broken down into seven major drainage basins,
designated as Basins W.1, E.1, E.2, OS.1, OS.2, OS.3, and OS.4. However, there are
only five basins within the project boundaries (W.1, E.1, E.2, OS.3, and OS.4), the
other two basins (OS.1 and OS.2) are associated with East Harmony Road.
Basin W.1
Basin W.1 is located along the eastern side of Larimer County Ditch #2 and a portion
of the multifamily building and front courtyard. The majority of runoff generated in this
basin comes from the multifamily roof. Runoff from the roof will enter roof leaders
which will convey the flow directly to an isolator row associated with the underground
West Pond located underneath the emergency access drive aisle. The remaining
portion of runoff is generated within the paved and landscaping areas directly west of
the building. Runoff generated in this area will enter the underground Stormtech
chambers via 5’ Type R inlet located at the south end of the emergency access drive.
Water quality and detention will both occur in MC-4500 Stormtech chambers. The
isolator row associated with the West Pond will be wrapped in a geotextile membrane
to reduce sediment migration. Basin W.1 will release at a portion of the reduced
historic 2-year release rate via a flow control manhole. The runoff will be released
directly into the Mail Creek Floodway.
Basin E.1
Basin E.1 is located along the eastern property boundary and is also associated with
the a decent portion of the multifamily building roof, the southeast parking lot, and a
small portion of landscaping. A majority of the runoff is produced via the roof which is
routed directly to an isolator row associated with the underground East Pond via roof
leaders and storm pipe. The remaining portion of the runoff is generated within the
parking lot and landscaping areas. Runoff from the parking lot and landscaping areas
will be conveyed into one of two 5’ Type R inlets located along the southern edges of
the parking lot. Both inlets convey runoff directly into an isolator row associated with
East Pond. Water quality and detention will both occur in MC-4500 Stormtech
chambers. Basin E.1 will release at a portion of the reduced historic 2-year release via
a flow control manhole. The runoff will be released directly into the Mail Creek
Floodway.
Basin E.2
Basin E.2 contains all the landscaping north of the multifamily building. Runoff
generated in this area will sheet flow north into Harmony Road. Once into Harmony
Road it will flow west to east via curb and gutter and eventually enter a proposed
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Quadruple Combination (Type 13) inlet within the new turn lane. In the case that the
Quadruple Combination inlet gets clogged the runoff generated in Basin E.2 will
overtop a high point directly east of the inlet within Harmony Road. It will continue to
be conveyed east to its previous ultimate design location, at the intersection of
Boardwalk Drive and Harmony Road, into an existing irrigation ditch. Once in the
inlet the runoff will be conveyed via the same storm sewer that Basin E.1 utilizes.
Runoff is conveyed directly into an isolator row associated with East Pond. Water
quality and detention will both occur in the MC-4500 Stormtech chambers. Basin E.2
will release at a portion of the reduced historic 2-year release rate via a flow control
manhole.
Basin OS.1
Basin OS.1 is 100% asphalt and is associated with the area that is 15’ north of the
north property line and extended the entire width of the property line, which is
equivalent to a local road section. Even though this area is not within the projects
boundaries, Brick Stone Apartments will provide detention and water quality for the
runoff generated within this area. Runoff generated in Basin OS.1 will enter a new
Quadruple Combination (Type 13) inlet; the same inlet that Basin E.2 is utilizing. In
the case that the Quadruple Combination inlet gets clogged the runoff generated in
Basin OS.1 will overtop a high point directly east of the inlet within Harmony Road. It
will continue to be conveyed east to its previous ultimate design location, at the
intersection of Boardwalk Drive and Harmony Road, into an existing irrigation ditch.
Once in the inlet the runoff will be conveyed via the same storm system that Basins
E.1 and E.2 are being conveyed in. Runoff will be routed to MC-4500 Stormtech
chambers located underneath the southern parking lot. Water quality and detention
will both occur in the MC-4500 Stormtech. Basin OS.1 will release at a portion of the
reduced historic 2-year release rate via the same flow control manhole that basin E.1
and E.2 are utilizing.
Basin OS.2
Basin OS.2 is the same basin as the previously discussed Basin OS1 from the historic
analysis. Basin OS.2 consists of the remaining portion of East Harmony Road that
wasn’t included in Basin OS.1 all along the north property line. Runoff generated
within this basin will also be captured by the new Quadruple Combination (Type 13)
inlet. However, Basin OS.2 will not be detained within East Pond but will receive
water quality to ensure that the underground system isn’t compromised with excess
sediment build up. In the case that the Quadruple Combination inlet gets clogged the
runoff generated in Basin OS.2 will overtop a high point directly east of the inlet within
Harmony Road. It will continue to be conveyed east to its previous ultimate design
location, at the intersection of Boardwalk Drive and Harmony Road, into an existing
irrigation ditch. The runoff generated within Basin OS.2 will bypass the triple
combination inlet, that Basins OS.1 and E.2 are utilizing.
Basin OS.3
Basin OS.3 is within the limits of disturbance and occupies the area just south of the
multifamily building and west of the southern parking lot and consists of landscaping,
pedestrian sidewalks, and retaining walls. Historically this basin sheet flows south to
Mail Creek undetained and untreated but because the Brick Stone Apartments is
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Final Drainage Report 10
increasing the imperviousness of this area the runoff generated from this basin will be
subtracted from the max allowable historic 2-year release rate. Basin OS.3 will
continue to sheet flow south directly into Mail Creek untreated and undetained.
Basin OS.4
Basin OS.4 is associated with Larimer County Ditch #2 and the remaining portion of
the undisturbed natural landscaping areas outside of the limits of disturbance and a
portion of land within the limits of disturbance. Due to existing conditions and grades
it would be impractical to reduce the allowable release rate by a factor that is
associated with runoff generated within Basin OS.4. Therefore, runoff generated from
this basin will not be subtracted from the max allowable historic 2-year release rate
because historic drainage patterns and historic imperviousness is maintained. Runoff
generated in Basin OS.4 will continue to sheet flow south into Mail Creek.
B. Specific Details
1. The main drainage problems associated with this project site are the deficiency of
existing stormwater infrastructure present, steep existing grades, city floodplains,
existing drainage ditches, and an influx of runoff generated from East Harmony Road
entering the site. Currently the majority of the site drains south via sheet flow directly
into Mail Creek. The proposed site will mitigate these issues by instituting the
following water quality devices:
Basins W.1, E.1, E.2, OS.1, and OS.2 will be routed directly into isolator rows
within the Stormtech chambers.
The Stormtech isolator rows will be wrapped with a geotextile membrane to avoid
sediment migration.
Restrictor plates will be placed at each of the two outfalls to control flow leaving
the underground facilities.
Due to layout constraints the isolator rows in both East and West pond contain
more chambers than required. Therefore, Brick Stone Apartments will be providing
more water quality than what is required.
Basin OS.2 will receive water quality within East Pond but will not be detained
and will be bypassed through the underground system.
2. The release rate for the undeveloped land (pre-development) was established by
calculating the Historic 2-year peak runoff rate for the entire project area (Basin H1)
and reducing it by the runoff from Basin OS.3’s 100-year event (1.00 cfs) because it
is leaving the developed site undetained and untreated. The overall historic 2-year
peak runoff rate was calculated at 2.27 cfs, resulting in a maximum release rate of
1.27 cfs for the developed basins (W.1, E.1, E.2, and OS.1). This release rate was
utilized in the FAA procedure detention storage computations (Refer to Appendix B for
these calculations).
3. Detention Pond Calculations
Brick Stone Apartments has two separate underground detention facilities and they
have a combined max release rate of 1.27 cfs. The release rate for each pond was
determined as a portion of the max release rate. West Pond is associated only with
Basin W.1 which occupies 30% of the area associated with Basins W.1, E.1, E.2,
and OS.1. Therefore, the West Pond will release at a rate of 30% of the max release
rate, allowing for a release rate of 0.39 cfs. The remaining 70% of the max release
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rate of 1.29 cfs will be allocated to East Pond, allowing for a release rate of 0.88 cfs.
Adding those two release rates together (0.39 cfs + 0.88 cfs) brings the max release
rate from the site to 1.27 cfs. As previously mentioned Basin OS.2 will be receiving
water quality but will not be detained within the East Pond because it will be
bypassing the system. Basin OS.2 has a 100-year flow of 5.64 cfs which will be
allowed to bypass East Pond. So in the 100-year event East Pond will be releasing at
6.52 cfs (5.64 cfs + 0.88 cfs = 6.52 cfs).
Detention will be provided onsite in the form of underground detention using MC-
4500 chambers from Stormtech.
West Pond
The FAA method was used to size the underground pond for detention. Calculations
for West Pond, based on characteristics of Basin W.1 with an adjusted release rate of
0.39 cfs, formulate a detention volume of 7,944 cu. ft. In order to detain 7,944 cu.
ft a total of 38 MC-4500 chambers will be used. West Pond will discharge south
towards Mail Creek through a flow control manhole.
East Pond
The FAA method was used to size the underground pond for detention. Calculations
for East Pond, based on characteristics of Basins E.1, E.2, and OS.1 with an
adjusted release rate of 0.88 cfs, formulate a detention volume of 20,799 cu. ft. In
order to detain 20,799 cu. ft. a total of 114 MC-4500 chambers will be used. East
Pond will discharge south towards Mail Creek through a flow control manhole.
4. Water Quality Results
Basin W.1
Basin W.1’s water quality will be provided via Stormtech Isolator chambers.
Following UDFCD standards, a required WQCV of 772 cu. ft. must be provided for
Basin W.1. In order to achieve this volume a minimum of 5 MC-4500 chambers are
required to be wrapped in a geotextile membrane to reduce sediment migration and
also promote infiltration into the aggregate base associated with the underground
system. However, Brick Stone Apartments is going to wrap 13 of the MC-4500
chambers associated with West Pond because of the limited space underneath the
emergency access drive. Therefore, Brick Stone Apartments is going above and
beyond in terms of providing water quality for Basin W.1.
Basin E.1, E.2, OS.1, and OS.2
Basin’s E.1, E.2, OS.1, and OS.2 will also have water quality provided via Stormtech
Isolator chambers. Following UDFCD standards, a required WQCV of 2,770 cu. ft.
must be provided for Basins E.1, E.2, OS.1 and OS.2. Please note that it is not
required of Brick Stone Apartments to treat Basin OS.2 but to guarantee that East
Pond isn’t saturated with excess sediment from Basin OS.2 bypassing through the
system Brick Stone Apartments has decided to treat this runoff. In order to achieve
this volume a minimum of 18 MC-4500 chambers are required to be wrapped in a
geotextile membrane. However, Brick Stone Apartments is going to wrap 54 of the
MC-4500 chambers associated with East Pond because of the configuration of the
underground facility and where roof leaders can tie into the system. Therefore, Brick
Stone Apartments is going above and beyond in terms of providing water quality for
Basins E.1, E.2, OS.1 and OS.2.
5. West pond will have a total of 38 MC-4500 chambers, 13 of them will be
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wrapped with a geotextile membrane for water quality purposes.
6. East Pond will have a total of 114 MC-4500 chambers, 54 of them will be
wrapped with a geotextile membrane for water quality purposes
7. Water quality chambers are only a portion of the detention chambers and are
not stand alone entities.
8. In the case that any of the inlets within Basin W.1 and E.1 get clogged runoff
will overtop the curb and gutter and flow south towards Mail Creek as it has
historically.
9. In the case that the Quadruple Combination (Type 13) inlet within the turn
lane gets clogged runoff will pond about 5.95” before overtopping the
highpoint within the turn lane and then flow east towards S. Boardwalk Drive
where it will enter the existing irrigation ditch, where it has historically gone.
10. Historic slopes found within the project site vary greatly across the entire site
ranging from 2:1 all the way to 30:1 along the northern edge of the site. Brick
Stone Apartments attempted to maintain slopes no greater than 4:1 but
unfortunately along the southeastern edge of the limits of disturbance there
are proposed slopes of 3:1. By utilizing a 3:1 slope in this area it allowed the
limits of disturbance to be as minimal as possible. Historically this area has
always been at a slope equal to or greater than 3:1. The erosion control plan
has indicated these areas to be reinforced with an erosion control blanket to
minimize erosion.
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the Brick Stone Apartments project complies with
the City of Fort Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with the Brick Stone Apartments project complies with
the City of Fort Collins’ Master Drainage Plan for the Mail Creek Basin.
3. There are city regulatory floodplains and erosion buffer zones associated with the
Brick Stone Apartments project. Nonstructural development will meet the standards of
Section 10-202 of the City Municipal Code. The boundaries of the floodplain and
erosion buffer zone are included on all the plans so that it is readily evident that Brick
Stone Apartments is not disturbing or altering it.
4. The drainage plan and stormwater management measures proposed with the Brick
Stone Apartments development 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. Brick Stone Apartments will detain for a portion
of the previous and proposed offsite runoff. Brick Stone Apartments will be releasing at
a reduced 2-year historic rate during the developed 100-year storm.
2. Brick Stone Apartments will provide water quality for runoff that was not originally
anticipated to be treated on site.
Brick Stone Apartments
Final Drainage Report 13
3. The proposed Brick Stone Apartments development will not impact the Master
Drainage Plan recommendations for the Mail Creek major drainage basin.
Brick Stone Apartments
Final Drainage Report 14
References
1. Final Drainage Report for Fort Collins Supportive Housing, May 25, 2007, S. A. Miro, Inc.
2. 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.
3. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No.
174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code.
4. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
5. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
6. 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
Brick Stone Apartments
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: Brick Stone Apartments
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen
Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….0.. 50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year C
f = 1.00 100-year C
f = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Pavers
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
H1 187189 4.30 0.000 0.008 0.000 0.183 0.000 4.11 0.26 0.26 0.33 2%
OS1 36978 0.85 0.837 0.000 0.000 0.000 0.000 0.01 0.94 0.94 1.00 99%
TOTAL 224167 5.15 0.837 0.008 0.000 0.183 0.000 4.12 0.29 0.29 0.37 18%
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
Brick Stone Apartments
Overland Flow, Time of Concentration:
Project: Brick Stone Apartments
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt
= L / 60V
Tc
= Ti
+ Tt
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf=1.00)
C*Cf
(10-yr
Cf=1.00)
C*Cf
(100-yr
Cf=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Slope,
S
(%)
Brick Stone Apartments
Rational Method Equation: Project: Brick Stone Apartments
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
h1 H1 4.30 13 13 12 0.26 0.26 0.33 2.02 3.45 7.29 2.27 3.88 10.26
os1 OS1 0.85 8 8 8 0.94 0.94 1.00 2.40 4.10 8.59 1.92 3.27 7.29
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
B. Mathisen
January 20th, 2017
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
Q = C f ( C )( i )( A )
Page 3 of 23 Historic D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs (Historic).xlsx\Direct-Runoff
Brickstone Apartments
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: Brickstone Apartments
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen
Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….0.. 50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year C
f = 1.00 100-year C
f = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Pavers
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
W.1 30972.0 0.711 0.000 0.092 0.498 0.000 0.000 0.12 0.83 0.83 1.00 75%
E.1 53892.0 1.237 0.362 0.251 0.559 0.000 0.000 0.07 0.91 0.91 1.00 88%
E.2 16432.1 0.377 0.000 0.104 0.000 0.000 0.000 0.27 0.44 0.44 0.55 25%
OS.1 9619.7 0.221 0.221 0.000 0.000 0.000 0.000 0.00 0.95 0.95 1.00 100%
OS.2 24691.4 0.567 0.567 0.000 0.000 0.000 0.000 0.00 0.95 0.95 1.00 100%
Brickstone Apartments
Overland Flow, Time of Concentration:
Project: Brickstone Apartments
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt
= L / 60V
Tc
= Ti
+ Tt
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf
=1.00)
C*Cf
(10-yr
Cf
=1.00)
C*Cf
(100-yr
Cf
=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Brickstone Apartments
Rational Method Equation: Project: Brickstone Apartments
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
w1 W.1 0.71 9 9 5 0.83 0.83 1.00 2.30 3.93 9.95 1.36 2.32 7.07
e2/e3 E.1 1.24 5 5 5 0.91 0.91 1.00 2.85 4.87 9.95 3.22 5.50 12.31
e1 E.2 0.38 8 8 6 0.44 0.44 0.55 2.46 4.21 9.31 0.41 0.70 1.95
e1 OS.1 0.22 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.60 1.02 2.20
e1 OS.2 0.57 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 1.53 2.62 5.64
OS.3 0.18 8 8 6 0.47 0.47 0.59 2.46 4.21 9.31 0.21 0.36 1.00
OS.4 1.85 18 18 17 0.27 0.27 0.34 1.70 2.90 6.20 0.86 1.46 3.91
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
B. Mathisen
January 29, 2017
Q = C f ( C )( i )( A )
Page 3 of 23 Proposed D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs(Proposed_final).xlsx\Direct-Runoff
Brickstone Apartments
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: Brickstone Apartments
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen
Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date: January 29, 2017
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….. 0.50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25
Design Point Basin IDs
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Pavers
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite Runoff
Coefficient
10-year
Composite Runoff
Coefficient
100-year
Composite Runoff
Coefficient
Composite
% Imperv.
e1 E.2, OS.1, OS.2 50743 1.16 0.79 0.10 0.00 0.00 0.00 0.27 0.79 0.79 0.98 76%
e E.1, E.2, & OS.1 79944 1.84 0.58 0.36 0.56 0.00 0.00 0.34 0.82 0.82 1.00 77%
COMBINED DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
**Soil Classification of site is Sandy Loam**
10-year Cf = 1.00
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
Page 4 of 23 Proposed D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs(Proposed_final).xlsx\Comb-C-Values
Brickstone Apartments
Overland Flow, Time of Concentration:
Project: Brickstone Apartments
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt
= L / 60V
Tc
= Ti
+ Tt
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf
=1.00)
C*Cf
(10-yr
Cf
=1.00)
C*Cf
(100-yr
Cf
=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Brickstone Apartments
Rational Method Equation: Project: Brickstone Apartments
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
e1 E.2, OS.1, OS.2 1.16 5 7 7 0.79 0.79 0.98 2.85 4.44 8.80 2.6 4.1 10.1
e E.1, E.2, & OS.1 1.84 8 11 12 0.82 0.82 1.00 2.40 3.63 7.16 3.6 5.5 13.1
Flow,
Q100
(cfs)
C2
C10
C100
Intensity,
i2
(in/hr)
Intensity,
i10
(in/hr)
Intensity,
i100
(in/hr)
COMBINED DEVELOPED RUNOFF COMPUTATIONS
B. Mathisen
January 29, 2017
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
Design
Point
Basin(s)
Area, A
(acres)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
Flow,
Q2
(cfs)
Flow,
Q10
(cfs)
Q = C f ( C )( i )( A )
Page 6 of 23 Proposed D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs(Proposed_final).xlsx\Comb-Direct-Runoff
Brickstone Apartments
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
w1 W.1 0.71 0.83 1.00 9.1 5.0 1.36 7.07
e2/e3 E.1 1.24 0.91 1.00 5.0 5.0 3.22 12.31
e1 E.2 0.38 0.44 0.55 7.7 6.4 0.41 1.95
e1 OS.1 0.22 0.95 1.00 5.0 5.0 0.60 2.20
e1 OS.2 0.57 0.95 1.00 5.0 5.0 1.53 5.64
OS.3 0.18 0.47 0.59 8.0 6.5 0.21 1.00
OS.4 1.85 0.27 0.34 18.3 16.8 0.86 3.91
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
e1 E.2, OS.1, OS.2 1.16 0.79 0.98 5.0 7.4 2.61 10.07
e E.1, E.2, & OS.1 1.84 0.82 1.00 8.1 12.5 3.62 13.14
Page 7 of 23 D:\Projects\Proposed 1229-001\Drainage\Hydrology\1229-001_Rational-Calcs(Proposed_final).xlsx\SUMMARY-TABLE
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 – Storm Sewers
B.2 – Inlets
B.3 – Detention Facilities
APPENDIX B.1
STORM SEWERS
APPENDIX B.2
INLETS
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 = 0.000 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 = 75.0 ft
Gutter Width W = 1.74 ft
Street Transverse Slope SX = 1.100 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 = 37.5 37.5 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no) check = yes
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 4.04 Released November 2016
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Brick Stone Apartments
Inlet E4.1
UD-Inlet_Inlet E2.1.xlsm, Inlet E2.1 1/31/2017, 11:58 AM
Design Information (Input) MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 3.00 3.00 inches
Number of Unit Inlets (Grate or Curb Opening) No = 1 1
Water Depth at Flowline (outside of local depression) Ponding Depth = 6.0 6.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) = N/A N/A feet
Width of a Unit Grate Wo = N/A N/A feet
Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = N/A N/A
Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = N/A N/A
Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = N/A N/A
Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = N/A N/A
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) = 5.00 5.00 feet
Height of Vertical Curb Opening in Inches Hvert = 6.00 6.00 inches
Height of Curb Orifice Throat in Inches Hthroat = 6.00 6.00 inches
Angle of Throat (see USDCM Figure ST-5) Theta = 63.40 63.40 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 1.74 1.74 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) = 3.60 3.60
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.67 0.67
Low Head Performance Reduction (Calculated) MINOR MAJOR
Depth for Grate Midwidth dGrate = N/A N/A ft
Depth for Curb Opening Weir Equation dCurb = 0.36 0.36 ft
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.77 0.77
Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = N/A N/A
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 5.6 5.6 cfs
Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK) Q PEAK REQUIRED = 0.8 3.1 cfs
CDOT Type R Curb Opening
INLET IN A SUMP OR SAG LOCATION
Version 4.04 Released November 2016
H-Vert
H-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT Type R Curb Opening
Override Depths
UD-Inlet_Inlet E2.1.xlsm, Inlet E2.1 1/31/2017, 11:58 AM
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 = 0.000 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.012
Height of Curb at Gutter Flow Line HCURB = 6.00 inches
Distance from Curb Face to Street Crown TCROWN = 90.0 ft
Gutter Width W = 1.74 ft
Street Transverse Slope SX = 1.100 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 = 90.0 90.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no) check = yes
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 4.04 Released November 2016
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Brick Stone Apartments
Inlet E5.1
UD-Inlet_Inlet E5.1.xlsm, Inlet E3.2 1/31/2017, 3:19 PM
Design Information (Input) MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 3.00 3.00 inches
Number of Unit Inlets (Grate or Curb Opening) No = 1 1
Water Depth at Flowline (outside of local depression) Ponding Depth = 6.0 6.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) = N/A N/A feet
Width of a Unit Grate Wo = N/A N/A feet
Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = N/A N/A
Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = N/A N/A
Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = N/A N/A
Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = N/A N/A
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) = 5.00 5.00 feet
Height of Vertical Curb Opening in Inches Hvert = 6.00 6.00 inches
Height of Curb Orifice Throat in Inches Hthroat = 6.00 6.00 inches
Angle of Throat (see USDCM Figure ST-5) Theta = 63.40 63.40 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 1.74 1.74 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) = 3.60 3.60
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.67 0.67
Low Head Performance Reduction (Calculated) MINOR MAJOR
Depth for Grate Midwidth dGrate = N/A N/A ft
Depth for Curb Opening Weir Equation dCurb = 0.36 0.36 ft
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.77 0.77
Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = N/A N/A
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 5.6 5.6 cfs
Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK) Q PEAK REQUIRED = 0.3 1.1 cfs
CDOT Type R Curb Opening
INLET IN A SUMP OR SAG LOCATION
Version 4.04 Released November 2016
H-Vert
H-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT Type R Curb Opening
Override Depths
UD-Inlet_Inlet E5.1.xlsm, Inlet E3.2 1/31/2017, 3:19 PM
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK = 13.0 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 = 0.012
Height of Curb at Gutter Flow Line HCURB = 6.00 inches
Distance from Curb Face to Street Crown TCROWN = 50.0 ft
Gutter Width W = 2.00 ft
Street Transverse Slope SX = 0.020 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 = 0.012
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX = 15.0 15.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 10.0 inches
Allow Flow Depth at Street Crown (leave blank for no) check = yes
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 4.04 Released November 2016
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 E13
Inlet E13.xlsm, Inlet E13 1/31/2017, 3:17 PM
Design Information (Input) MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 2.00 2.00 inches
Number of Unit Inlets (Grate or Curb Opening) No = 4 4
Water Depth at Flowline (outside of local depression) Ponding Depth = 6.0 6.4 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 0.552 ft
Depth for Curb Opening Weir Equation dCurb = 0.33 0.36 ft
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.57 0.60
Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 0.87 0.89
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.57 0.60
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 8.6 10.1 cfs
WARNING: Inlet Capacity less than Q Peak for Major Storm Q PEAK REQUIRED = 2.6 10.1 cfs
CDOT/Denver 13 Combination
INLET IN A SUMP OR SAG LOCATION
Version 4.04 Released November 2016
H-Vert
H-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT/Denver 13 Combination
Override Depths
Inlet E13.xlsm, Inlet E13 1/31/2017, 3:17 PM
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK = 15.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.067 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.018
Height of Curb at Gutter Flow Line HCURB = 6.00 inches
Distance from Curb Face to Street Crown TCROWN = 110.0 ft
Gutter Width W = 1.74 ft
Street Transverse Slope SX = 0.060 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 = 0.012
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX = 20.0 20.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no) check = yes
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 4.04 Released November 2016
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Brick Stone Apartments
Inlet W4.1
UD-Inlet_Inlet W3.1.xlsm, Inlet W3.1 1/31/2017, 3:22 PM
Design Information (Input) MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 3.00 3.00 inches
Number of Unit Inlets (Grate or Curb Opening) No = 1 1
Water Depth at Flowline (outside of local depression) Ponding Depth = 6.0 6.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) = N/A N/A feet
Width of a Unit Grate Wo = N/A N/A feet
Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = N/A N/A
Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = N/A N/A
Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = N/A N/A
Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = N/A N/A
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) = 5.00 5.00 feet
Height of Vertical Curb Opening in Inches Hvert = 6.00 6.00 inches
Height of Curb Orifice Throat in Inches Hthroat = 6.00 6.00 inches
Angle of Throat (see USDCM Figure ST-5) Theta = 63.40 63.40 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 1.74 1.74 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) = 3.60 3.60
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.67 0.67
Low Head Performance Reduction (Calculated) MINOR MAJOR
Depth for Grate Midwidth dGrate = N/A N/A ft
Depth for Curb Opening Weir Equation dCurb = 0.36 0.36 ft
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.77 0.77
Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = N/A N/A
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 5.6 5.6 cfs
Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK) Q PEAK REQUIRED = 0.3 1.2 cfs
CDOT Type R Curb Opening
INLET IN A SUMP OR SAG LOCATION
Version 4.04 Released November 2016
H-Vert
H-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT Type R Curb Opening
Override Depths
UD-Inlet_Inlet W3.1.xlsm, Inlet W3.1 1/31/2017, 3:22 PM
2.10
APPENDIX B.3
DETENTION FACILITIES
Pond No :
1
100-yr
1.00
13.00 min 20799 ft3
1.84 acres 0.477 ac-ft
Max Release Rate = 0.88 cfs
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 5477 1.00 0.88 264 5213
10 7.720 8500 1.00 0.88 528 7972
15 6.520 10768 0.93 0.82 739 10029
20 5.600 12331 0.83 0.73 871 11460
25 4.980 13707 0.76 0.67 1003 12704
30 4.520 14930 0.72 0.63 1135 13794
35 4.080 15722 0.69 0.60 1267 14455
40 3.740 16471 0.66 0.58 1399 15072
45 3.460 17143 0.64 0.57 1531 15611
50 3.230 17781 0.63 0.55 1663 16118
55 3.030 18348 0.62 0.54 1795 16553
60 2.860 18893 0.61 0.54 1927 16966
65 2.720 19466 0.60 0.53 2059 17406
70 2.590 19961 0.59 0.52 2191 17770
75 2.480 20479 0.59 0.52 2323 18155
80 2.380 20963 0.58 0.51 2455 18508
85 2.290 21431 0.58 0.51 2587 18844
90 2.210 21899 0.57 0.50 2719 19180
95 2.130 22279 0.57 0.50 2851 19428
100 2.060 22681 0.57 0.50 2983 19697
105 2.000 23121 0.56 0.49 3115 20006
110 1.940 23495 0.56 0.49 3247 20248
115 1.890 23930 0.56 0.49 3379 20551
120 1.840 24310 0.55 0.49 3511 20799
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
A =
Tc =
Project Location :
Design Point
C =
Design Storm
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
Q = 0.88 cfs
C = 0.604
Q = Release Rate (cfs) Eh = 5016.39 ft
C = Discharge Coefficients (unitless) Ei = 5004.40 ft
Aa = Area Allowed of Opening (ft2)
g = Gravity (32.2 ft/s2) 0.05244 ft2
Eh = High Water Surface Elevation (ft) 7.551412 in2
Ei = Elevation of Outlet Invert (ft)
H = Height of Opening (in.)
R = Inner Radius of Outfall Pipe (in.)
Δ = Top of Plate to Center of Pipe (in.)
S = Arc Length of Open Area (in.)
Ac = Area of Opening (in2)
θ = Angle of Plate on Pipe to Center Pipe (radians)
Calculated Area of Opening (Ac)
Design Height of Opening (H)
Proposed Outfall Pipe Diameter
7.03 sq. in.
B. Mathisen
January 31, 2017
Aa =
1-1/4 in
15 in
1229-001
Brick Stone Apartments
East Pond
[ ( ( ) ) ]
2
2
R
Sin S
R
R S
K
−
=
Q = CA 2 g ( E h − E i )
S = R θ
( ) ( R )
Cos
R
Cos → = ∆
2 = ∆ 2 −1
θ θ
Ac = π R 2 − K
Pond No :
1
100-yr
1.00
5.00 min 7944 ft3
0.71 acres 0.182 ac-ft
Max Release Rate = 0.39 cfs
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 2119 1.00 0.39 117 2002
10 7.720 3289 0.75 0.29 176 3113
15 6.520 4166 0.67 0.26 234 3932
20 5.600 4771 0.63 0.24 293 4479
25 4.980 5304 0.60 0.23 351 4953
30 4.520 5777 0.58 0.23 410 5367
35 4.080 6083 0.57 0.22 468 5615
40 3.740 6373 0.56 0.22 527 5846
45 3.460 6633 0.56 0.22 585 6048
50 3.230 6880 0.55 0.21 644 6236
55 3.030 7099 0.55 0.21 702 6397
60 2.860 7310 0.54 0.21 761 6550
65 2.720 7532 0.54 0.21 819 6713
70 2.590 7723 0.54 0.21 878 6846
75 2.480 7924 0.53 0.21 936 6988
80 2.380 8111 0.53 0.21 995 7117
85 2.290 8292 0.53 0.21 1053 7239
90 2.210 8473 0.53 0.21 1112 7362
95 2.130 8620 0.53 0.21 1170 7450
100 2.060 8776 0.53 0.20 1229 7547
105 2.000 8946 0.52 0.20 1287 7659
110 1.940 9091 0.52 0.20 1346 7745
115 1.890 9259 0.52 0.20 1404 7855
120 1.840 9406 0.52 0.20 1463 7944
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
A =
Tc =
Project Location :
Design Point
C =
Design Storm
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
Q = 0.39 cfs
C = 0.605
Q = Release Rate (cfs) Eh = 5023.96 ft
C = Discharge Coefficients (unitless) Ei = 5016.06 ft
Aa = Area Allowed of Opening (ft2)
g = Gravity (32.2 ft/s2) 0.028584 ft2
Eh = High Water Surface Elevation (ft) 4.116134 in2
Ei = Elevation of Outlet Invert (ft)
H = Height of Opening (in.)
R = Inner Radius of Outfall Pipe (in.)
Δ = Top of Plate to Center of Pipe (in.)
S = Arc Length of Open Area (in.)
Ac = Area of Opening (in2)
θ = Angle of Plate on Pipe to Center Pipe (radians)
7/8 in
12 in
1229-001
Brick Stone Apartments
West Pond
Calculated Area of Opening (Ac)
Design Height of Opening (H)
Proposed Outfall Pipe Diameter
3.70 sq. in.
B. Mathisen
January 31, 2017
Aa =
[ ( ( ) ) ]
2
2
R
Sin S
R
R S
K
−
=
Q = CA 2 g ( E h − E i )
S = R θ
( ) ( R )
Cos
R
Cos → = ∆
2 = ∆ 2 −1
θ θ
Ac = π R 2 − K
APPENDIX C
WATER QUALITY DESIGN COMPUTATIONS
Project Title Date:
Project Number Calcs By:
Client
Basins
1
WQCV = Watershed inches of Runoff (inches) 78.25%
a = Runoff Volume Reduction (constant)
i = Total imperviousness Ratio (i = Iwq
/100) 0.318 in
A = 2.40 ac
V = 0.0636 ac-ft
V = Water Quality Design Volume (ac-ft)
WQCV = Water Quality Capture Volume (inches)
A = Watershed Area (acres)
2770 cu. ft.
Drain Time
a =
i =
WQCV =
Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event
Brick Stone Apartments January 26, 2016
1229-001 B. Mathisen
SEEC Enterprises
East Pond
0.231
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
WQCV (watershed inches)
Total Imperviousness Ratio (i = Iwq
/100)
Water Quality Capture Volume
6 hr
12 hr
24 hr
40 hr
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
V * A
12
WQCV
Vault ID
Total
Required
WQ Volume
(cf)
Flow,
WQ
(cfs)
Chamber
Type
Chamber Release
Ratea
(cfs)
Chamber
Volumeb
(cf)
Installed Camber
w/ Aggregatec
(cf)
Mimimum
No. of
Chambersd
Total Release
Ratee
(cfs)
Required
Storage
Volume by
FAA Method
(cf)
Mimimum
No. of
Chambersf
Storage
Provided
within the
Chambersg
(cf)
Total
Installed
System
Volumeh
(cf)
East Pond 2770 2.88 MC-4500 0.028 106.50 162.60 18 0.51 0 0 0 2927
SC-740
a. Release rate per chamber, limited by flow through geotextile with accumulated sediment.
b. Volume within chamber only, not accounting for void spaces in surrounding aggregate.
c. Volume includes chamber and void spaces (40%) in surrounding aggregate, per chamber unit.
d. Number of chambers required to provide full WQCV within total installed system, including aggregate.
e. Release rate per chamber times number of chambers.
f. Number of chambers required to provide required FAA storage volume stored within the chamber only (no aggregate storage).
g. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume.
h. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required WQCV.
Chamber Configuration Summary
D:\Projects\1229-001\Drainage\WatQual\East Pond WQ Chambers(with offsite basin).xlsx
Project Title Date:
Project Number Calcs By:
Client
Basins
1
WQCV = Watershed inches of Runoff (inches) 75.00%
a = Runoff Volume Reduction (constant)
i = Total imperviousness Ratio (i = Iwq
/100) 0.300 in
A = 0.71 ac
V = 0.0177 ac-ft
V = Water Quality Design Volume (ac-ft)
WQCV = Water Quality Capture Volume (inches)
A = Watershed Area (acres)
Brick Stone Apartments January 26, 2016
1229-001 B. Mathisen
SEEC Enterprises
West Pond
772 cu. ft.
Drain Time
a =
i =
WQCV =
Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event
0.231
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
WQCV (watershed inches)
Total Imperviousness Ratio (i = Iwq
/100)
Water Quality Capture Volume
6 hr
12 hr
24 hr
40 hr
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
V * A
12
WQCV
Vault ID
Total
Required
WQ Volume
(cf)
Flow,
WQ
(cfs)
Chamber
Type
Chamber Release
Ratea
(cfs)
Chamber
Volumeb
(cf)
Installed Camber
w/ Aggregatec
(cf)
Mimimum
No. of
Chambersd
Total Release
Ratee
(cfs)
Required
Storage
Volume by
FAA Method
(cf)
Mimimum
No. of
Chambersf
Storage
Provided
within the
Chambersg
(cf)
Total
Installed
System
Volumeh
(cf)
East Pond 772 0.68 MC-4500 0.028 106.50 162.60 5 0.14 0 0 0 813
SC-740
a. Release rate per chamber, limited by flow through geotextile with accumulated sediment.
b. Volume within chamber only, not accounting for void spaces in surrounding aggregate.
c. Volume includes chamber and void spaces (40%) in surrounding aggregate, per chamber unit.
d. Number of chambers required to provide full WQCV within total installed system, including aggregate.
e. Release rate per chamber times number of chambers.
f. Number of chambers required to provide required FAA storage volume stored within the chamber only (no aggregate storage).
g. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume.
h. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required WQCV.
Chamber Configuration Summary
D:\Projects\1229-001\Drainage\WatQual\West Pond WQ Chambers.xlsx
APPENDIX D
EROSION CONTROL REPORT
Brick Stone Apartments
Final Erosion Control Report
A comprehensive Erosion and Sediment Control Plan (along with associated details) will be 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 along the disturbed perimeter, gutter protection in the adjacent roadways
and inlet protection at 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 C7.00 of the Utility Plans. The Utility
Plans at final design 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 will
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 StormWater 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
Soils Resource 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
Natural Area, Colorado
Resources
Conservation
Service
June 15, 2016
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 (http://
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
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bases apply to all programs.) Persons with disabilities who require alternative means
2
for communication of program information (Braille, large print, audiotape, etc.) should
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complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400
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(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..................................................................................................................7
Soil Map................................................................................................................8
Legend..................................................................................................................9
Map Unit Legend................................................................................................10
Map Unit Descriptions........................................................................................10
Larimer County Area, Colorado......................................................................12
4—Altvan-Satanta loams, 3 to 9 percent slopes.........................................12
74—Nunn clay loam, 1 to 3 percent slopes.................................................13
References............................................................................................................15
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
scientists classified and named the soils in the survey area, they compared the
5
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
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
6
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.
7
8
Custom Soil Resource Report
Soil Map
4485740 4485760 4485780 4485800 4485820 4485840 4485860 4485880
4485740 4485760 4485780 4485800 4485820 4485840 4485860 4485880
493570 493590 493610 493630 493650 493670 493690 493710 493730 493750 493770 493790
493570 493590 493610 493630 493650 493670 493690 493710 493730 493750 493770 493790
40° 31' 25'' N
105° 4' 33'' W
40° 31' 25'' N
105° 4' 23'' W
40° 31' 20'' N
105° 4' 33'' W
40° 31' 20'' N
105° 4' 23'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,110 if printed on A landscape (11" x 8.5") sheet.
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: http://websoilsurvey.nrcs.usda.gov
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
Map Unit Legend
Larimer County Area, Colorado (CO644)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
4 Altvan-Satanta loams, 3 to 9
percent slopes
2.2 56.1%
74 Nunn clay loam, 1 to 3 percent
slopes
1.7 43.9%
Totals for Area of Interest 3.9 100.0%
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
Custom Soil Resource Report
10
intensive use of small areas is planned, however, onsite investigation is needed to
define and locate the soils and miscellaneous areas.
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
11
Larimer County Area, Colorado
4—Altvan-Satanta loams, 3 to 9 percent slopes
Map Unit Setting
National map unit symbol: jpwf
Elevation: 5,200 to 6,200 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: Farmland of statewide importance
Map Unit Composition
Altvan and similar soils: 55 percent
Satanta and similar soils: 35 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Altvan
Setting
Landform: Fans, benches, terraces
Landform position (three-dimensional): Base slope, side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 9 inches: loam
H2 - 9 to 16 inches: clay loam, loam, sandy clay loam
H2 - 9 to 16 inches: loam, fine sandy loam, silt loam
H2 - 9 to 16 inches: gravelly sand, gravelly coarse sand, coarse sand
H3 - 16 to 31 inches:
H3 - 16 to 31 inches:
H3 - 16 to 31 inches:
H4 - 31 to 60 inches:
H4 - 31 to 60 inches:
H4 - 31 to 60 inches:
Properties and qualities
Slope: 6 to 9 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high
(0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Available water storage in profile: Very high (about 13.7 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 4e
Custom Soil Resource Report
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Hydrologic Soil Group: B
Description of Satanta
Setting
Landform: Structural benches, terraces
Landform position (three-dimensional): Side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium and/or eolian deposits
Typical profile
H1 - 0 to 9 inches: loam
H2 - 9 to 14 inches: loam, clay loam, sandy clay loam
H2 - 9 to 14 inches: loam, clay loam, fine sandy loam
H2 - 9 to 14 inches:
H3 - 14 to 60 inches:
H3 - 14 to 60 inches:
H3 - 14 to 60 inches:
Properties and qualities
Slope: 3 to 6 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high
(0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Available water storage in profile: Very high (about 27.4 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: B
Minor Components
Nunn
Percent of map unit: 6 percent
Larimer
Percent of map unit: 4 percent
74—Nunn clay loam, 1 to 3 percent slopes
Map Unit Setting
National map unit symbol: jpxn
Elevation: 4,800 to 5,600 feet
Custom Soil Resource Report
13
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
Nunn and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Nunn
Setting
Landform: Terraces, fans
Landform position (three-dimensional): Base slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Alluvium
Typical profile
H1 - 0 to 10 inches: clay loam
H2 - 10 to 60 inches: clay loam, clay
H2 - 10 to 60 inches:
Properties and qualities
Slope: 1 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: High
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to
moderately high (0.06 to 0.20 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 18.9 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: C
Minor Components
Ulm
Percent of map unit: 10 percent
Satanta
Percent of map unit: 5 percent
Custom Soil Resource Report
14
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
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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
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MAP POCKET
HISTORIC DRAINAGE EXHIBIT
PROPOSED DRAINAGE EXHIBIT
S
CONTROL
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w
e1
EXISTING DRAINAGE
CULVERT
EROSION BUFFER ZONE
PER CITY OF FORT COLLINS
CITY FLOOD RISK MAP
MAIL CREEK FLOODWAY
FORT COLLINS SUPPORTIVE
HOUSING SUBDIVISION
LOT 26
FAIRWAY ESTATES
FAIRWAY ESTATES
LOT 26
FAIRWAY ESTATES 3RD
EAST HARMONY ROAD
(PUBLIC R.O.W. VARIES)
FAIRWAY ESTATES
F
UD
UD UD UD
LARIMER COUNTY DITCH #2
FLOW CONTROL MANHOLE
os.2
CTIY FLOODPLAIN
INLET E5.1
INLET E4.1
INLET W4.1
INLET E13
PEDESTRIAN BRIDGE
RIP RAP
TOP OF BANK
TOP OF BANK
TOP OF BANK
3:1
3:1
4:1
3:1
4:1
4:1
4:1
3:1
8:1
4:1
4:1
??? ??? ???
(3.3:1)
(3.8:1)
(1.4:1)
(1.1:1)
(2.1:1)
(3.8:1)
(2.8:1)
(9.5:1)
(2.7:1)
(2.6:1)
(3.2:1)
(3.3:1)
(9.2:1)
(7.0:1)
(2.9:1)
(2.5:1)
(3.9:1)
(3.8:1)
8575 - 5006.91 NAVD 88
8385 - 5003.11 NAVD 88
8830 - 5010.09 NAVD 88
FFE=29.50 FFE=29.50
FFE=17.50
acres
E.1
0.91 1.24
1.00
acres
OS.4
0.27 1.85
0.34
acres
W.1
0.83 0.71
1.00
acres
OS.1
0.95 0.22
1.00
acres
E.2
0.44 0.38
0.55
acres
OS.2
0.95 0.57
1.00
acres
OS.3
0.47 0.19
0.59
e
10' DRAINAGE EASEMENT
e3
e2
w1
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's below.
Call before you dig.
R
GRAPHIC SCALE:
LEGEND:
EXISTING INLET GRATE
EXISTING DECID. TREE
EXISTING CONIF. TREE
EXISTING LIGHT POLE
EXISTING STUMP
ST EXISTING STORM SEWER LINE
EXISTING CURB/GUTTER FLOWLINE
EXISTING EDGE OF ASPHALT
acres
A2
0.25 0.08
0.31
a3
4950
4950
4:1
79.45
HP
SLOPE
PROPOSED OVERLAND FLOW DIRECTION
CONCENTRATED FLOW DIRECTION
PROPOSED SWALE FLOWLINE
PROPOSED INFLOW CURB/GUTTER FLOWLINE
PROPOSED STORM DRAIN WITH INLET
DRAINAGE BASIN
PROPOSED CONTOUR
PROPOSED FLOWLINE ELEVATION
PROPOSED SCOUR STOP
EXISTING CONTOUR
DRAINAGE BASIN AREA
DESIGN POINT
DRAINAGE BASIN ID
DRAINAGE BASIN MINOR/MAJOR COEFF.
EXISTING OVERLAND FLOW DIRECTION
PROPOSED OUTFALL CURB/GUTTER FLOWLINE
RUNOFF SUMMARY TABLE:
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
1.REFER TO THE "FINAL DRAINAGE REPORT FOR BRICK STONE APARTMENTS" BY NORTHERN ENGINEERING, DATED JUNE 2016 FOR ADDITIONAL INFORMATION.
NOTES:
( IN FEET )
0
1 INCH = 40 FEET
40 40 80 120
NORTH
City Engineer Date
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer Date
APPROVED:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
Water & Wastewater Utility
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
Environmental Planner
C8.01
DRAINAGE EXHIBIT
B. Mathisen
B. Mathisen
1"=40'
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
w1 W.1 0.71 0.83 1.00 9.1 5.0 1.36 7.07
e2/e3 E.1 1.24 0.91 1.00 5.0 5.0 3.22 12.31
e1 E.2 0.38 0.44 0.55 7.7 6.4 0.41 1.95
e1 OS.1 0.22 0.95 1.00 5.0 5.0 0.60 2.20
e1 OS.2 0.57 0.95 1.00 5.0 5.0 1.53 5.64
OS.3 0.18 0.47 0.59 8.0 6.5 0.21 1.00
OS.4 1.85 0.27 0.34 18.3 16.8 0.86 3.91
24
No. Revisions:
By: Date:
REVIEWED BY:
N. Hawes
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
02.01.17
PROJECT:
1229-001
Sheet
of 24
BRICK STONE APARTMENTS ON HARMONY
DRAWING FILENAME: D:rojects\1229-001\Dwg\Drng\1229-001_DRNG.dwg LAYOUT NAME: 1229-001_DRNG - C8.01 DATE: Jan 31, 2017 - 3:42pm CAD OPERATOR: blaine
LIST OF XREFS: [1229-001_xSITE] [1229-001_xEXST] [1229-001_xGRAD] [1229-001_xTOPO] [NES-xborder] [1229-001_xPutil]
These drawings are
instruments of service
provided by Northern
Engineering Services, Inc.
and are not to be used for
any type of construction
unless signed and sealed by
a Professional Engineer in
the employ of Northern
Engineering Services, Inc.
NOT FOR CONSTRUCTION
REVIEW SET
E N G I N E E R I N G
N O R T H E RN
02.01.17
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
www.northernengineering.com
Phone: 970.221.4158
/ /
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/ /
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/ / / / / / / / / /
/ /
/ / / / / / / / /
/ / / / /
/ / /
acres
H1
0.26 4.41
0.32
acres
OS1
0.94 0.85
1.00
MAIL CREEK FLOODWAY
EROSION BUFFER ZONE
PER CITY OF FORT COLLINS
CITY FLOOD RISK MAP
LOT 26
FAIRWAY ESTATES
LOT 25
FAIRWAY ESTATES
FAIRWAY ESTATES
LOT 26
FAIRWAY ESTATES 3RD
EAST HARMONY ROAD
(PUBLIC R.O.W. VARIES)
FAIRWAY ESTATES
LARIMER COUNTY DITCH #2
EXISTING PIPES APPEAR
TO BE ABANDONED
EXISTING ROADSIDE DITCH
EXISTING
RIPRAP RUNDOWN
EXISTING IRRIGATION
CONCRETE STRUCTURE
EXISTING 24" RCP
CITY FLOODPLAIN
\A1;CITY FLOODPLAIN
EXISTING CONCRETE
BOX CULVERTS
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what's below.
Call before you dig.
R
GRAPHIC SCALE:
LEGEND:
EXISTING INLET GRATE
EXISTING DECID. TREE
EXISTING CONIF. TREE
EXISTING LIGHT POLE
EXISTING STUMP
ST EXISTING STORM SEWER LINE
EXISTING CURB/GUTTER FLOWLINE
EXISTING EDGE OF ASPHALT
acres
A2
0.25 0.08
0.31
a3
4950
4950
4:1
79.45
HP
SLOPE
PROPOSED OVERLAND FLOW DIRECTION
CONCENTRATED FLOW DIRECTION
PROPOSED SWALE FLOWLINE
PROPOSED INFLOW CURB/GUTTER FLOWLINE
PROPOSED STORM DRAIN WITH INLET
DRAINAGE BASIN
PROPOSED CONTOUR
PROPOSED FLOWLINE ELEVATION
PROPOSED RIPRAP
EXISTING CONTOUR
DRAINAGE BASIN AREA
DESIGN POINT
DRAINAGE BASIN ID
DRAINAGE BASIN MINOR/MAJOR COEFF.
EXISTING OVERLAND FLOW DIRECTION
PROPOSED OUTFALL CURB/GUTTER FLOWLINE
RUNOFF SUMMARY TABLE:
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
1.REFER TO THE "FINAL DRAINAGE REPORT FOR BRICK STONE APARTMENTS" BY NORTHERN ENGINEERING, DATED JUNE 2016 FOR ADDITIONAL INFORMATION.
NOTES:
( IN FEET )
0
1 INCH = 40 FEET
40 40 80 120
NORTH
City Engineer Date
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer Date
APPROVED:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
Water & Wastewater Utility
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
Environmental Planner
C8.00
HISTORIC DRAINAGE EXHIBIT
B. Mathisen
B. Mathisen
1"=40'
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
h1 H1 4.30 0.26 0.33 12.7 11.7 2.27 10.26
os1 OS1 0.85 0.94 1.00 8.3 7.9 1.92 7.29
23
No. Revisions:
By: Date:
REVIEWED BY:
N. Hawes
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
02.01.17
PROJECT:
1229-001
Sheet
of 24
BRICK STONE APARTMENTS ON HARMONY
DRAWING FILENAME: D:rojects\1229-001\Dwg\Drng\1229-001_EX_DRNG.dwg LAYOUT NAME: 1229-001_EX_DRNG- C8.00 DATE: Jan 31, 2017 - 3:42pm CAD OPERATOR: blaine
LIST OF XREFS: [1229-001_xEXST] [1229-001_xTOPO] [NES-xborder]
These drawings are
instruments of service
provided by Northern
Engineering Services, Inc.
and are not to be used for
any type of construction
unless signed and sealed by
a Professional Engineer in
the employ of Northern
Engineering Services, Inc.
NOT FOR CONSTRUCTION
REVIEW SET
E N G I N E E R I N G
N O R T H E RN
02.01.17
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
www.northernengineering.com
Phone: 970.221.4158
the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 10, Sep 22, 2015
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr 28,
2011
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor shifting
of map unit boundaries may be evident.
Custom Soil Resource Report
9
=
40 hr
=
40 hr
1229-001
Brickstone Apartments
Project Number :
Project Name :
West Pond
Page 1 of 1
1229-001_West Pond_DetentionVolume_FAAModified Method.xls
1229-001
Brickstone Apartments
Project Number :
Project Name :
East Pond
Page 1 of 1
1229-001_East Pond_DetentionVolume_FAAModified Method.xls
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
e1 E.2, OS.1, OS.2 No 0.79 0.79 0.98 15 2.10% 1.8 1.8 0.7 150 0.50% 1.41 1.8 N/A N/A 5 7 7
e E.1, E.2, & OS.1 No 0.82 0.82 1.00 64 2.15% 3.2 3.2 1.2 452 0.60% 1.55 4.9 N/A N/A 8 11 12
COMBINED DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
B. Mathisen
January 29, 2017
Design
Point
Basin IDs
Overland Flow Gutter/Pipe Flow Swale Flow Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
Page 5 of 23 Proposed D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs(Proposed_final).xlsx\Comb-Tc-10-yr_&_100-yr
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
w1 W.1 No 0.83 0.83 1.00 203 0.50% 9.1 9.1 3.4 25 100.00% 20.00 0.0 N/A N/A N/A 9 9 5
e2/e3 E.1 No 0.91 0.91 1.00 166 1.10% 4.4 4.4 2.3 147 3.20% 3.58 0.7 N/A N/A N/A 5 5 5
e1 E.2 No
0.44 0.44 0.55 64 2.10% 7.7 7.7 6.4 N/A N/A N/A N/A N/A 8 8 6
e1 OS.1 No
0.95 0.95 1.00 10 0.80% 1.0 1.0 0.6 61 0.50% 1.41 0.7 N/A N/A N/A 5 5 5
e1 OS.2 No
0.95 0.95 1.00 85 2.00% 2.1 2.1 1.4 149 4.00% 4.00 0.6 N/A N/A N/A 5 5 5
OS.3 No 0.47 0.47 0.59 85 2.50% 8.0 8.0 6.5 N/A N/A N/A N/A N/A 8 8 6
OS.4 No
0.27 0.27 0.34 311 3.30% 18.3 18.3 16.8 N/A N/A N/A N/A N/A 18 18 17
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter/Pipe Flow Swale Flow
Design
Point
Basin
Overland Flow
B. Mathisen
January 29, 2017
Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
Page 2 of 23 Proposed D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs(Proposed_final).xlsx\Tc-10-yr_&_100-yr
OS.3 7935.0 0.182 0.000 0.058 0.000 0.000 0.000 0.12 0.47 0.47 0.59 29%
OS.4 80461.0 1.847 0.000 0.025 0.000 0.102 0.000 1.72 0.27 0.27 0.34 3%
TOTAL 224003 5.142 1.150 0.530 1.056 0.102 0.000 2.30 0.58 0.58 0.73 51%
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
10-year Cf
= 1.00
January 29, 2017
**Soil Classification of site is Clay Loam**
Page 1 of 23 Proposed D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs(Proposed_final).xlsx\C-Values
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
h1 H1 No 0.26 0.26 0.33 294 9.44% 12.7 12.7 11.7 N/A N/A N/A N/A N/A 13 13 12
os1 OS1 No 0.94 0.94 1.00 31 3.30% 1.1 1.1 0.7 665 0.60% 1.55 7.2 N/A N/A N/A 8 8 8
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter/Pipe Flow Swale Flow
Design
Point
Basin
Overland Flow
B. Mathisen
January 20th, 2017
Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
Page 2 of 23 Historic D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs (Historic).xlsx\Tc-10-yr_&_100-yr
10-year Cf
= 1.00
January 20th, 2017
**Soil Classification of site is Clay Loam**
Page 1 of 23 Historic D:\Projects\1229-001\Drainage\Hydrology\1229-001_Rational-Calcs (Historic).xlsx\C-Values