HomeMy WebLinkAboutTHE MARK - FDP240013 - SUBMITTAL DOCUMENTS - ROUND 1 - Drainage Related Document
July 31, 2024
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage Report for
The Mark
Dear Staff:
Northern Engineering is pleased to submit this Final Drainage Report for your review.
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 Johnson Drive 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.
Cassandra Ungerman, PE
Project Engineer
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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 ....................................................................... 5
A. Major Basin Description .................................................................................................................... 5
B. Sub-Basin Description ....................................................................................................................... 5
III. DRAINAGE DESIGN CRITERIA ................................................................................... 7
A. Regulations........................................................................................................................................ 7
B. Four Step Process .............................................................................................................................. 7
C. Development Criteria Reference and Constraints ............................................................................ 8
D. Hydrological Criteria ......................................................................................................................... 8
E. Hydraulic Criteria .............................................................................................................................. 8
F. Floodplain Regulations Compliance .................................................................................................. 9
G. Modifications of Criteria ................................................................................................................... 9
IV. DRAINAGE FACILITY DESIGN .................................................................................... 9
A. General Concept ............................................................................................................................... 9
B. Specific Details ................................................................................................................................ 11
V. CONCLUSIONS ...................................................................................................... 12
A. Compliance with Standards ............................................................................................................ 12
B. Drainage Concept ............................................................................................................................ 13
References ....................................................................................................................... 14
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations
B.1 – Storm Sewers
B.2 – Sidewalk Chase
B.3 – Detention Facilities
APPENDIX C – Water Quality Design Computations
APPENDIX D – Erosion Control Report
APPENDIX E – Soils Resource Report
APPENDIX F - FEMA Mapping
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LIST OF TABLES AND FIGURES:
Figure 1 Vicinity Map .......................................................................................................... 1
Figure 2 Aerial Photograph ................................................................................................... 2
Figure 3 Proposed Site Plan ................................................................................................. 3
Figure 4 FEMA Map ............................................................................................................ 4
Figure 5 City Floodplain Mapping .......................................................................................... 5
MAP POCKET:
C6.00 – Proposed Drainage Exhibit
C6.01 – Floodplain Exhibit
Historic Drainage Exhibit
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I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
Figure 1 Vicinity Map
2. Johnson Drive Apartments project site is located in the replat of lots 13, 14, 15, 16,
and 17 Spring Court Subdivision which is located in the northeast quarter of Section
23, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort
Collins, County of Larimer, State of Colorado.
3. The project site is located at 255 Johnson Drive at southwest corner of the
intersection of Johnson Drive and Spring Court. The property is bounded to the north
by Johnson Drive and further north by Spring Creek, to the east by Spring Court, to
the south by and irrigation lateral and to the west by BNSF Railway and the Max
route.
4. The project site lies within the Spring Creek Basin. The project site has historically
drained towards Spring Court and Johnson Drive via overland flow from south to
northeast. The site must provide current City Low-Impact Design (LID) requirements
and water quality treatment as well. Water quality treatment methods are described
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in further detail below.
5. As this is an in-fill site, the area surrounding the property is fully developed.
6. There are no off-site flows that enter the project area.
B. Description of Property
1. Johnson Drive Apartments project is approximately 2.80 net acres.
Figure 2 Aerial Photograph
2. There are currently five properties being utilized for this project; one commercial lot
(Self-Storage) and four residential lots. The existing commercial lot routes
stormwater via overland and gutter flow and releases undetained into Johnson Drive.
Once in Johnson Drive, stormwater travels via gutter flow to the east where it is
intercepted by an existing inlet and conveyed directly to Spring Creek. The four
residential lots route stormwater via overland flow and releases undetained into Spring
Court. Once in Spring Court, stormwater travel via gutter flow to the north to Johnson
Drive, with the ultimate destination being Spring Court. The overall existing
impervious area located within in the four properties is 89,123 sq. ft. and was
released undetained. There are currently no water quality measures located on-site.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey, the site consists of Altvan-Satanta and Kim
loams, which fall into Hydrologic Soil Groups B. The NRCS soils report is provided in
Appendix E.
4. The proposed development is primarily composed of a proposed student housing
building. Associated site work that will be constructed with this project include water
services, sanitary sewer services, storm sewer, landscaped swales and walls, and
sidewalks along the north, south and east side of the building. Current City Low-
Impact Design (LID) requirements will be implemented with the project, and will
consist of sand filter, which is further discussed in Section IV, below.
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Figure 3 Proposed Site Plan
5. There are no known irrigation laterals crossing the site. There is an irrigation lateral
bordering the south side of the property.
6. The project site is within a General Commercial District (CG). The proposed use is
permitted within this zone district.
C. Floodplain
1. The project site is encroached by the FEMA designated 100- Year High Risk Flood
Fringe according to FIRM Panel 08069C87G for Larimer County, effective February
26, 2018.
2. Development is allowed within the flood fringe. It should be noted that the portion of
the structure that will be constructed within the floodplain with the development of
Johnson Drive Apartments. Commercial and Residential spaces will be elevated 18”
above the Base Flood Elevation at all openings (Regulatory Flood Protection Elevation
RFPE). The garage will be elevated 12” above the Base Flood Elevation and
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hydraulic venting will be provided. Floodproofing of portions of the structure below the
RFPE will be provided.
3. A no-rise certification will be required for the storm sewer outfall into the floodway.
4. The building foundation is proposed to be concrete spread footings under perimeter
walls and columns. All being supported by structural piers.
5. As per Section 10-103 (9), Critical Facilities are prohibited in the floodplain. The
definition of Critical Facilities includes facilities for at-risk populations (daycares,
schools, nursing homes, et.), facilities utilizing hazardous materials (gas stations, auto
repair, laboratories), emergency services facilities (urgent care, hospitals, fire, police)
and government services (municipal offices, library). A floodplain use permit is
required prior to building permit issuance.
6. Development within the floodplain must comply with Chapter 10 of the Municipal
Code.
7. Please see appendix for a Floodplain Exhibit and all regulatory notes regarding
development within the floodplain.
Figure 4 FEMA Map
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Figure 5 City Floodplain Mapping
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site lies within the Spring Creek Basin. Detention requirements for this
site are to detain the difference between the 100-yr developed flow rate and the
historic 100-yr release of all existing impervious area and 2-yr release rate from the
existing landscaping areas. The project is composed of five different lots, one is a
commercial lot and the other four are single-family residential lots. Historically, the
lots sheet flow into the surrounding streets undetained. However, Johnson Drive
Apartments will release at a reduced historic rate and will also provide water quality.
The proposed release rate will be reduced to summation of the historic 2-year event
within the existing landscape areas and the historic 100-year event within all the
existing impervious areas. Water quality will be provided for all the paved areas via a
sand filter within the building. All other water quality will be provided by sheet
flowing across landscape areas.
2. There are no previous drainage studies for the area associated with Johnson Drive
Apartments project site.
B. Sub-Basin Description
Johnson Drive Apartments historically drains overland from south to north except for
the southwest corner of the site which is picked up by an irrigation lateral running
west to east. Runoff from the site has historically flowed overland north towards
Spring Creek and eventually enters the Cache La Poudre.
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Basin HW1 Pervious
Historic Basin HW1 Pervious is 0.19 acres and is roughly the western 2/3 of the
property, and it is only comprised of landscaping area. Runoff generated in this basin
historically sheet flows north into Johnson Drive. Once in Johnson Drive runoff will be
conveyed west to east via curb and gutter until it enters a curb inlet and is further
conveyed to Spring Creek. Basin HW1 Pervious has a 2-yr runoff of 0.04 cfs.
Basin HW1 Impervious
Historic Basin HW1 Impervious is 1.54 acres and is roughly the western 2/3 of the
property, and it is only comprised of the paved and roof areas associated with
Johnson Drive Storage. Runoff generated in this basin historically sheet flows north
into Johnson Drive. Once in Johnson Drive runoff will be conveyed west to east via
curb and gutter until it enters a curb inlet and is further conveyed to Spring Creek.
Basin HW1 Impervious has a 100-yr runoff of 15.35 cfs.
Overall Basin HW is 1.73 acres and has a combined allowable release rate of 15.39
cfs (0.04 cfs + 15.35 cfs) from Basins HW1 Pervious 2-year event and HW1
Impervious 100-year event.
Basin HE1 Pervious
Historic Basin HE1 Pervious is 0.60 acres and is roughly the eastern 1/3 of the
property, and it is only comprised of landscaping area. Runoff generated in this basin
historically sheet flows directly into Spring Court and is then conveyed north via curb
and gutter until it enters a curb inlet and is conveyed to Spring Creek. Basin HE1
Pervious has a 2-yr runoff of 0.12 cfs.
Basin HE1 Impervious
Historic Basin HE1 Impervious is 0.21 acres and is roughly the eastern 1/3 of the
property, and it is comprised of the paved sidewalks and roof areas. Runoff generated
in this basin historically sheet flows directly into Spring Court and is then conveyed
north via curb and gutter until it enters a curb inlet and is conveyed to Spring Creek.
Basin HE1 Impervious has a 100-yr runoff of 1.95 cfs.
Overall Basin HE is 0.81 acres and has a combined release rate of 2.07 cfs (0.12 cfs
+ 1.95 cfs) from Basins HE1 Pervious 2-year event and HE1 Impervious 100-year
event.
Basin HS1 Pervious
Historic Basin HS1 Pervious is 0.27 acres and is situated in the southwest corner of
the project site. Runoff generated in this area will sheet flow into an existing irrigation
lateral that runs west to east. There is also a small detention pond in this area that is
serving the property to the south of the project site. This area will remain untouched
during the development of Johnson Drive Apartments. Basin HW1 Pervious has a 2-yr
runoff of 0.08 cfs.
Basin HS1 Impervious
Historic Basin HS1 Impervious is 0 acres because it is all vegetated. Basin HW1
Impervious has a 100-yr runoff of 0 cfs.
Overall Basin HS1 is 0.27 acres and has a combined release rate of 0.08 cfs (0.08
cfs + 0 cfs) from Basins HS1 Pervious and HS1 Impervious.
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Allowable Release from Site
The overall historic release rate from the site is 17.54 cfs (15.39 cfs + 2.07 cfs +
0.08 cfs). However, due to uncapturable flows from Johnson Drive Apartments, which
is discussed in Section IV.A, the allowable release rate is reduced.
A full-size copy of the Historic and Proposed Drainage Exhibits 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 Johnson Drive
Apartments project.
B. Four Step Process
The overall stormwater management strategy employed with the Johnson Drive
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 redeveloped from the
current use by implementing multiple Low-Impact Development (LID) strategies including:
Providing as much vegetated open areas as possible along the east, west and south
portion of the site to reduce the overall impervious area and to minimize directly
connected impervious areas (MDCIA).
Selecting a site that has been previously developed to reduce development impacts.
Routing flows, to the extent feasible, through a stormwater detention vault located
internal to the building for water quality purposes. Stormwater will be routed through a
sand filter to increase filtration.
Providing on-site detention to increase time of concentration, and reduce loads on
downstream storm infrastructure.
Routing runoff from the roof directly into the sand filter.
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; however, urban
development of this intensity will still generate stormwater runoff that will require
additional BMPs and water quality. The stormwater runoff from the site will be
intercepted and treated using an internal stormwater vault with a water quality capture
volume.
Step 3 – Stabilize Drainageways
There is one major drainageway within the subject property, Sherwood Lateral. While this
step may not seem applicable to proposed development, the project indirectly helps
achieve stabilized drainageways nonetheless. By providing detention and water quality
treatment where none previously existed, sediment and flash flows with erosion potential
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are removed from downstream drainageway systems. Furthermore, this project will pay
one-time stormwater development fees, as well as ongoing monthly stormwater utility fees,
both of which help achieve City-wide drainageway stability. Additionally, Johnson Drive
Apartments does not intend to alter the south side of the north bank stabilizing the
Sherwood Lateral. Also, Johnson Drive Apartments will be maintaining the North side
slope of the lateral by tying in at the same elevations as the top of the bank
Step 4 – Implement Site Specific and Other Source Control BMPs .
The proposed project includes one multi-story building, covered parking areas within the
structure, retaining walls, and pedestrian sidewalks, all of which will require the need for
site specific source controls including:
A localized trash enclosure placed within the building.
The proposed development will provide LID features within the stormwater vault
internal to the building to provide enhanced water quality. The Sand Filter is designed
to capture the first flush storm event; thus, eliminating sources of potential pollution
previously left exposed to weathering and runoff processes.
C. Development Criteria Reference and Constraints
1. There are no known drainage studies for the existing property.
2. The subject property is a redevelopment project and 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 north, south, east, and west property lines will be
maintained.
Overall drainage patterns of the existing site will be maintained.
Release rates can not adversely impact existing infrastructure.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure 3.4-1 of the FCSCM, serve as the source for all hydrologic computations
associated with this development. Tabulated data contained in Table 3.4-1 has been
utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables 3.2-1 and 3.2-2 of the FCSCM.
3. The Rational Formula-based 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-yr recurrence
interval. The second event considered is the “Major Storm,” which has a 100-yr
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 maintains historic drainage patterns.
2. All drainage facilities proposed with the Johnson Drive Apartments project are
designed in accordance with criteria outlined in the FCSCM and/or the Urban
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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 encroaching a FEMA 100-
Year High Risk Flood Fringe.
F. Floodplain Regulations Compliance
As previously mentioned, the project site is encroaching a FEMA 100-Year High Risk Flood
Fringe along the northwest corner of the property. Development is allowed within the flood
fringe pursuant to Chapter 10 of the City of Fort Collins Municipal Code. It should be noted
that no structures will be constructed within the floodway with the development of Johnson
Drive Apartments. However, the building and all the landscaping walls do fall within the 100-
year moderate floodplain.
G. Modifications of Criteria
The proposed Johnson Drive Apartments development is not requesting any modifications.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the Johnson Drive Apartments drainage design are to maintain
existing drainage patterns and ensure no adverse impacts to any adjacent properties
or existing infrastructure.
2. As previously mentioned, there are no off-site flows draining onto the existing
property. Additionally, on-site LID feature will be provided which will enhance
downstream water quality. These measures are discussed further below.
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. The proposed Johnson Drive Apartments project is has been divided into five (5)
major drainage basins, designated as Basins A1, OW1, OS1, OS2, ON1 and ON2.
Drainage patterns for basins shown on the Proposed Drainage Exhibit are described
below.
Basin A1
Basin A1 has a net area of 1.670 acres, which corresponds to the entire building
footprint. Runoff generated in Basin A1 will be generated by the roof which will then
convey the runoff to an internal storm vault via roof leaders. The internal storm vault
will also be a sand filter therefore, 100% of the runoff from this basin is treated via
LID. Basin A1 will provide onsite detention that is required for the runoff volume
difference between the 100-year developed inflow rate and the 2-year historic release
rate for any net new impervious area. After Basin A1 is detained and treated, it will be
conveyed to Spring Creek via storm pipe. The 100-year runoff rate for Basin A1 is
16.62 cfs.
Basin OW1
Basin OW1 is located between the proposed apartment building and the Mason Street
corridor retaining wall and has a net area of 0.097 acres. This area is all landscaping
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but due to existing grades this area will be getting free released onto Johnson Drive via
a sidewalk chase. Once in the public right of way the runoff will make its way to an
existing inlet near the northeast corner of the intersection of Johnson Drive and Spring
Court. Since Basin OW1 is leaving the site undetained and untreated the overall
release rate will be modified to reflect this. The 100-year runoff rate for Basin OW1 is
0.12 cfs.
Basin OS1
Basin OS1 has a net area of 0.265 acre, and is associated with the Sherwood
Irrigation lateral and detention pond that occupy the southwest corner of the site. This
area has historically bypassed the site flowing east via the irrigation lateral. Johnson
Drive apartments will not be developing anything in this area therefore this runoff will
continue to flow east via the irrigation lateral. Because Johnson Drive Apartments is
not able to capture and treat this area runoff the max allowable release rate will be
reduced to reflect this. The 100-year runoff rate for Basin OS1 is 0.33 cfs.
Basin OS2
Basin OS2 has a net area of 0.288 acres, and is located along the southern edge of
the proposed apartment building and northern side of the irrigation lateral. All the
runoff generated in Basin OS2 will flow east towards Spring Court via a swale. Runoff
generated in Basin OS2 will freely discharge into Spring Court via a concrete chase.
Therefore, the max allowable release rate will be reduced to reflect that Basin OS2 is
not being detained or treated. The 100-year runoff rate for Basin OS2 is 0.51 cfs.
Basin ON1
Basin ON1 has a net area of 0.482 acres, and is located along the eastern and
northern edge of the proposed apartment building. All the flow generated in Basin
ON1 will leave the site undetained and untreated via overland flow. The runoff will
either enter Spring Court or Johnson Drive. Once in the public right of way the runoff
will make its way to an existing inlet near the northeast corner of the intersection of
Johnson Drive and Spring Court. From there the runoff will be conveyed to Spring
Creek via pipe. The 100-year runoff rate for Basin ON1 is 3.41 cfs.
Basin ON2
Basin ON2 has a net area of 0.090 acres and contains the northern portion of the
existing culdesac bulb. All the flow generated in Basin ON2 is historic and will be
captured in an existing inlet. From there the runoff will be conveyed to Spring Creek
via proposed pipe. This basin was included in these calculations in order to size the
proposed storm pipe. The existing storm pipe from this existing inlet is proposed to be
abandoned in place. As this basin is historic with no alterations to imperviousness,
this basin is not included in the calculations for allowable release rate. The 100-year
runoff rate for Basin ON2 is 0.89 cfs.
Max Allowable Release Rate
The max allowable release rate for Johnson Drive Apartments is 17.54 cfs (as shown
in Section IIb). The total undetained runoff from the basins ON1, OW1, OS1 and OS2
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totals 4.37 cfs. After subtracting the undetained runoff from the allowable release
rate, a total release rate of 13.17 cfs from Basin A1 was determined.
Due to limitations determined during design, an 18” pipe is the largest pipe that will
be allowed under Johnson Drive. As such, the release from Basin A1 Detention Pond
has been further reduced to 10.50 cfs. This reduction decreases the total release
from the Johnson Drive Apartments to 14.86 cfs (2.68 cfs below the total allowable
release).
B. Specific Details
1. The main drainage problems associated with this project site are the deficiency of
existing stormwater infrastructure present, steep existing grades, an existing irrigation
lateral running across the site, and FEMA floodplain. Currently the site drains to the
northeast. The proposed site will mitigate these issues by instituting the following
water quality and detention facilities:
Johnson Drive Apartments will be utilizing a sand filter to treat all the runoff
generated by Basin A1. The sand filter will be incorporated into the internal storm
chamber within the apartment building.
All the free released runoff will be generated by landscaping areas which will
provide minimal water quality via grass buffers.
2. Water Quality Chamber
Following UDFCD criteria and using the characteristics from Basin A1 wields an
overall water quality capture volume (WQCV) of 2,728 cu. ft. This water quality will
be provided via sand filter. With the current configuration of the internal storm
chamber the actual WQCV is 2,876.5 cu. ft.
All roof drains for the building will be directed to forebays inside the water quality
chamber. The forebays will dissipate the energy of the water before it enters the sand
filter. The sand filter is designed to filter the water and provide water quality through
an approved sand and aggregate section. A perforated pipe at the bottom of the sand
filter section will convey the treated water to the outfall pipe. During a larger storm
event, the sand filter chamber will fill and spill over a large weir into the detention
chamber.
3. Detention Chamber
Using the FAA Method to detain Basin A1 with a reduced release rate of 10.50 cfs
yields an overall detention volume of 3500 cu. ft. This required volume will be stored
in conjunction with the WQCV within the internal storm chamber. With the current
configuration of the internal storm chamber the actual detention volume is 4,914 cu.
ft. This chamber is sized for 40% more storage than is required. This volume does
not include the water quality volume. A 100-yr restrictor plate will be installed on the
outfall pipe to regulate the flow to the allowable release rate of 10.50 cfs.
4. Detention Overflow Path
In the case that the detention vault spills, an emergency overflow weir is provided
above the water quality chamber. This weir spills north into the parking garage. The
parking garage slab is sloped and channelized to convey the flow to the flood
openings in the exterior walls. These openings are set at finished grade and will
release the flow to the ground surface just north of the building.
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5. Below is a breakdown of the LID treatment of the proposed project site.
Basin ID Basin Area Percent
Impervious
Impervious
Area (ac) Treatment Type Impervious Area
Treated (ac)
A1 1.670 ac. 100% 1.670 ac. Sand Filter 1.670 ac.
OW1 0.097 ac. 6% 0.006 ac. N/A N/A
OS1 0.265 ac. 2% 0.005 ac. N/A N/A
OS2 0.288 ac. 13% 0.037 ac. N/A N/A
ON1 0.482 ac. 68% 0.328 ac. N/A N/A
Total 2.802 ac. 2.046 ac.
Percent of Total
Impervious Area
Treated w/ LID
82%
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the Johnson Drive Apartments project complies
with the City of Fort Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with the Johnson Drive Apartments project complies
with the City of Fort Collins’ Master Drainage Plan for the Spring Creek Basin.
3. The project site is encroached by a 100-Year Floodplain Fringe along the northwest
corner of the property. However, the development will not adversely impact any of the
downstream infrastructure, as this floodplain is caused by the obstruction of the
College Avenue bridge.
4. The drainage plan and stormwater management measures proposed with the Johnson
Drive Apartments development are compliant with all applicable State and Federal
regulations governing stormwater discharge.
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B. Drainage Concept
1. The drainage design proposed with this project will effectively limit potential damage
associated with its stormwater runoff.
2. Johnson Drive Apartments will be releasing at reduced runoff rates from the historic
condition to both Johnson Drive and Spring Court; therefore, there no negative
downstream impacts from this development are expected.
3. Johnson Drive Apartments will provide water quality for a majority of the site (1.670
acres out of 2.80 acres) with accepted LID treatments. The remaining portion of the
project site will receive water quality by crossing over landscaped areas. The areas
receiving water quality via landscaping were uncatchable and only include the
perimeter areas along the north, south, east, and west.
4. The proposed Johnson Drive Apartments development will not impact the Master
Drainage Plan recommendations for the Spring Creek major drainage basin.
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References
1. 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.
2. Fort Collins Stormwater Criteria Manual, dated December 2018, City of Fort Collins, Colorado, as
adopted by the City Council of the City of Fort Collins, as referenced in Section 26-500 of the
Municipal Code of the City of Fort Collins..
3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
5. 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
Character of Surface
Runoff
Coefficient1
Percent
Impervious1
0.95 100%
0.95 90%
0.50 40%
0.50 40%
0.10 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt,
Concrete (acres)Rooftop (acres) Gravel (acres) Pavers (acres)
Lawns, Sandy
Soil, Flat Slope <
2% (sq.ft.)
Lawns, Sandy
Soil, Flat Slope <
2% (acres)
Percent
Impervious C2*Cf C5*Cf C10*Cf C100*Cf
HW1 75,478 1.733 0.856 0.687 0.000 0.000 8283.00 0.19 85%0.86 0.86 0.86 1.00
HE1 35,074 0.805 0.074 0.136 0.000 0.000 25955.00 0.60 26%0.32 0.32 0.32 0.40
HS1 11,546 0.265 0.000 0.000 0.000 0.000 11546.00 0.27 2%0.10 0.10 0.10 0.13
Total 122,098 2.803 0.929 0.822 0.000 0.000 45784.00 1.05 60%0.63 0.63 0.63 0.79
HW1 (Impervious)67,195 1.543 0.856 0.687 0.000 0.000 0.00 0.00 96%0.95 0.95 0.95 1.00
HW1 (Pervious)8,283 0.190 0.000 0.000 0.000 0.000 8283.00 0.19 2%0.10 0.10 0.10 0.13
HE1 (Impervious)9,119 0.209 0.074 0.136 0.000 0.000 0.00 0.00 94%0.95 0.95 0.95 1.00
HE1 (Pervious)25,955 0.596 0.000 0.000 0.000 0.000 25955.00 0.60 2%0.10 0.10 0.10 0.13
HS1 (Impervious)0 0.000 0.000 0.000 0.000 0.000 0.00 0.00 2%0.10 0.10 0.10 0.13
HS2 (Pervious)11,546 0.265 0.000 0.000 0.000 0.000 11546.00 0.27 2%0.10 0.10 0.10 0.13
HISTORIC RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Gravel
Johnson Drive Apartments
S. Thomas
November 15, 2019
Project:
Calculations By:
Date:
Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).
Lawns, Sandy Soil, Flat Slope < 2%
USDA SOIL TYPE: A
Pavers Composite Runoff Coefficient2
Notes:
1) Runoff coefficients per Tables 3.2-1 & 3.2-2 of the Fort Collins Stormwater Manual. Percent impervious per Tables 4.1-2 & 4.1-3 of the Fort Collins Stormwater Manual.
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins Stormwater Manual.
Project:
Calculations By:
Date:
C2*Cf C10*Cf C100*Cf
Length
> 200'
Length
(ft)
Slope
(%)
Ti
2-Yr
(min)
Ti
10-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Length
(ft)
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Comp.
Tc 2-Yr
(min)
Max.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 10-Yr
(min)
Max.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Comp.
Tc 100-Yr
(min)
Max.
Tc 100-Yr
(min)
Tc
100-Yr
(min)
HW1 HW1 0.86 0.86 1.00 Pass 35 5.00%1.6 1.6 0.6 425 0.90 1.90 3.73 N/A N/A N/A 5.31 12.56 5.31 5.31 12.56 5.31 4.38 12.56 5.00
HE1 HE1 0.32 0.32 0.40 Pass 85 1.00%13.4 13.4 12.0 298 0.50 1.41 3.51 N/A N/A N/A 16.94 12.13 12.13 16.94 12.13 12.13 15.56 12.13 15.56
HS1 HS1 0.10 0.10 0.13 Pass 24 45.00%2.6 2.6 2.5 0 N/A N/A N/A N/A N/A N/A 2.58 10.13 5.00 2.58 10.13 5.00 2.51 10.13 5.00
HW1 (Impervious)HW1 (Impervious)0.95 0.95 1.00 Pass 35 5.00%1.0 1.0 0.6 425 0.90 1.90 3.73 N/A N/A N/A 4.70 12.56 5.00 4.70 12.56 5.00 4.38 12.56 5.00
HW1 (Pervious)HW1 (Pervious)0.10 0.10 0.13 Pass 35 5.00%6.5 6.5 6.3 425 0.90 1.90 3.73 N/A N/A N/A 10.20 12.56 10.20 10.20 12.56 10.20 10.04 12.56 10.04
HE1 (Impervious)HE1 (Impervious)0.95 0.95 1.00 Pass 85 1.00%2.6 2.6 1.7 298 0.50 1.41 3.51 N/A N/A N/A 6.10 12.13 6.10 6.10 12.13 6.10 5.24 12.13 5.24
HE1 (Pervious)HE1 (Pervious)0.10 0.10 0.13 Pass 85 1.00%17.2 17.2 16.8 298 0.50 1.41 3.51 N/A N/A N/A 20.75 12.13 12.13 20.75 12.13 12.13 20.32 12.13 20.32
HS1 (Impervious)HS1 (Impervious)0.10 0.10 0.13 Pass 24 45.00%2.6 2.6 2.5 0 N/A N/A N/A N/A N/A N/A 2.58 10.13 5.00 2.58 10.13 5.00 2.51 10.13 5.00
HS2 (Pervious)HS2 (Pervious)0.10 0.10 0.13 Pass 24 45.00%2.6 2.6 2.5 0 N/A N/A N/A N/A N/A N/A 2.58 10.13 5.00 2.58 10.13 5.00 2.51 10.13 5.00
November 15, 2019
Intensity, i (per Table 3.4-1 of the Fort Collins Stormwater Manual)
Velocity (Gutter Flow), V = 20·S½
Velocity (Swale Flow), V = 15·S½
S. Thomas
Rational Equation: Q = CiA (Equation 6-1)
Overland Flow, Time of Concentration:
HISTORIC TIME OF CONCENTRATION COMPUTATIONS
Channelized Gutter Flow Swale Flow
Design
Point Basin(s)
Tt = L / 60V (Equation 6-4 per UDFCD)
Tc = Ti + Tt (Equation 6-2 per UDFCD)
Overland Flow Time of Concentration
Johnson Drive Apartments
Gutter/Swale Flow, Time of Concentration:
(Equation 6-4 per UDFCD)
(Equation 3.3-2 per Fort Collins
Stormwater Manual)
}
𝑇 =1.87 1.1−𝐶∗𝐶𝑓𝐿
𝑆ଵ ଷൗ
Page 1 of 1
Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100
HW1 HW1 1.733 5.31 5.31 5.00 0.86 0.86 1.00 2.85 4.87 9.95 4.23 7.23 17.24
HE1 HE1 0.805 12.13 12.13 15.56 0.32 0.32 0.40 2.05 3.50 7.16 0.53 0.90 2.31
HS1 HS1 0.265 5.00 5.00 5.00 0.10 0.10 0.13 2.85 4.87 9.95 0.08 0.13 0.33
HW1 (Impervious)HW1 (Impervious)1.543 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 4.18 7.14 15.35
HW1 (Pervious)HW1 (Pervious)0.190 10.20 10.20 10.04 0.10 0.10 0.13 2.21 3.78 7.72 0.04 0.07 0.18
HE1 (Impervious)HE1 (Impervious)0.209 6.10 6.10 5.24 0.95 0.95 1.00 2.67 4.56 9.31 0.53 0.91 1.95
HE1 (Pervious)HE1 (Pervious)0.596 12.13 12.13 20.32 0.10 0.10 0.13 2.05 3.50 7.16 0.12 0.21 0.53
HS1 (Impervious)HS1 (Impervious)0.000 5.00 5.00 5.00 0.10 0.10 0.13 2.85 4.87 9.95 0.00 0.00 0.00
HS2 (Pervious)HS2 (Pervious)0.265 5.00 5.00 5.00 0.10 0.10 0.13 2.85 4.87 9.95 0.08 0.13 0.33
Total Allowable Release = 17.54
Notes
Total allowable release from Basin
HN1 = 15.39
Total allowable release from Basin
HN1 = 2.07
Total allowable release from Basin
HS1 = 0.08
HISTORIC DIRECT RUNOFF COMPUTATIONS
Intensity (in/hr) Flow (cfs)
Johnson Drive Apartments
S. Thomas
November 15, 2019
Overland Flow, Time of Concentration:
Project:
Tc = Ti + Tt (Equation 6-2)
Tt = L / 60V (Equation 6-4)
Gutter/Swale Flow, Time of Concentration:Calculations By:
Date:
Velocity (Swale Flow), V = 15·S½
Velocity (Gutter Flow), V = 20·S½
Intensity, I from Fig. RA-2
Rational Equation: Q = CiA (Equation 6-1)
Design
Point Basin Area
(ac.)
Runoff CTc (Min)
(Equation 6-4)
(Equation 6-3)
}
𝑇 =1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ଵ ଷൗ
Page 1 of 1
Character of Surface
Runoff
Coefficient1
Percent
Impervious1
0.95 100%
Percent Impervious changed to 100% with guidance from City 0.95 100%
0.50 40%
0.50 40%
0.10 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt,
Concrete
(sq.ft.)
Asphalt,
Concrete (acres)Rooftop (sq.ft.) Rooftop (acres) Gravel (sq.ft.) Gravel (acres) Pavers (sq.ft.) Pavers (acres)
Lawns, Sandy
Soil, Flat Slope <
2% (sq.ft.)
Lawns, Sandy
Soil, Flat Slope <
2% (acres)
Percent
Impervious C2*Cf C5*Cf C10*Cf C100*Cf
A1 72,754 1.670 0 0.000 72,754 1.670 0 0.000 0 0.000 0.00 0.00 100%0.95 0.95 0.95 1.00
ON1 20,997 0.482 13,851 0.318 0 0.000 724 0.017 0 0.000 6422.00 0.15 68%0.67 0.67 0.67 0.84
ON2 3,917 0.090 3,917 0.090 0 0.000 0 0.000 0 0.000 6422.00 0.00 100%0.95 0.95 0.95 1.00
OW1 4,242 0.097 152 0.003 0 0.000 0 0.000 0 0.000 4090.00 0.09 6%0.13 0.13 0.13 0.16
OS1 11,546 0.265 0 0.000 0 0.000 0 0.000 0 0.000 11546.00 0.27 2%0.10 0.10 0.10 0.13
OS2 12,540 0.288 1,436 0.033 0 0.000 0 0.000 0 0.000 11104.00 0.25 13%0.20 0.20 0.20 0.25
Total 125,996 2.892 19,356 0.444 72,754 1.670 724 0.017 0 0.000 33162.00 0.76 74%0.72 0.72 0.72 0.90
Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).
Lawns, Sandy Soil, Flat Slope < 2%
USDA SOIL TYPE: A
Pavers Composite Runoff Coefficient2
PROPOSED RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Gravel
Johnson Drive Apartments
S. Thomas
December 18, 2019
Project:
Calculations By:
Date:
Notes:
1) Runoff coefficients per Tables 3.2-1 & 3.2-2 of the Fort Collins Stormwater Manual. Percent impervious per Tables 4.1-2 & 4.1-3 of the Fort Collins Stormwater Manual.
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins Stormwater Manual.
Project:
Calculations By:
Date:
C2*Cf C10*Cf C100*Cf
Length
> 200'
Length
(ft)
Slope
(%)
Ti
2-Yr
(min)
Ti
10-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Length
(ft)
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Comp.
Tc 2-Yr
(min)
Max.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 10-Yr
(min)
Max.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Comp.
Tc 100-Yr
(min)
Max.
Tc 100-Yr
(min)
Tc
100-Yr
(min)
A1 A1 0.95 0.95 1.00 Pass N/A N/A N/A N/A 209 0.50 1.41 2.47 N/A N/A N/A 2.47 11.16 5.00 2.47 11.16 5.00 2.47 11.16 5.00
ON1 ON1 0.67 0.67 0.84 Pass 81 2.11%5.6 5.6 3.4 264 0.59 1.53 2.87 N/A N/A N/A 8.45 11.92 8.45 8.45 11.92 8.45 6.24 11.92 6.24
ON2 ON2 0.95 0.95 1.00 Pass 50 2.00%1.6 1.6 1.0 81 0.51 1.42 0.95 N/A N/A N/A 2.52 10.73 5.00 2.52 10.73 5.00 2.00 10.73 5.00
OW1 OW1 0.13 0.13 0.16 Pass 20 25.00%2.8 2.8 2.7 N/A N/A N/A 171 2.92%0.26 11.12 13.90 11.06 11.06 13.90 11.06 11.06 13.80 11.06 11.06
OS1 OS1 0.10 0.10 0.13 Pass 24 45.00%2.6 2.6 2.5 N/A N/A N/A N/A N/A N/A 2.58 10.13 5.00 2.58 10.13 5.00 2.51 10.13 5.00
OS2 OS2 0.20 0.20 0.25 Pass 34 5.09%5.7 5.7 5.4 N/A N/A N/A 335 2.00%0.21 26.32 32.04 12.05 12.05 32.04 12.05 12.05 31.73 12.05 12.05
Rational Equation: Q = CiA (Equation 6-1)
Overland Flow, Time of Concentration:
PROPOSED TIME OF CONCENTRATION COMPUTATIONS
Channelized Gutter Flow Swale Flow
Design
Point Basin(s)
Tt = L / 60V (Equation 6-4 per UDFCD)
Tc = Ti + Tt (Equation 6-2 per UDFCD)
Overland Flow Time of Concentration
Johnson Drive Apartments
Gutter/Swale Flow, Time of Concentration:
December 18, 2019
Intensity, i (per Table 3.4-1 of the Fort Collins Stormwater Manual)
Velocity (Gutter Flow), V = 20·S½
Velocity (Swale Flow), V = 15·S½
S. Thomas
(Equation 6-4 per UDFCD)
(Equation 3.3-2 per Fort Collins
Stormwater Manual)
}
𝑇 =1.87 1.1−𝐶∗𝐶𝑓𝐿
𝑆ଵ ଷൗ
Page 1 of 1
Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100
A1 A1 1.670 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 4.52 7.73 16.62 10.50
ON1 ON1 0.482 8.45 8.45 6.24 0.67 0.67 0.84 2.40 4.10 8.38 0.78 1.33 3.41 3.41
ON2 ON2 0.090 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.24 0.42 0.89 Not Included
OW1 OW1 0.097 11.06 11.06 11.06 0.13 0.13 0.16 2.13 3.63 7.42 0.03 0.05 0.12 0.12
OS1 OS1 0.265 5.00 5.00 5.00 0.10 0.10 0.13 2.85 4.87 9.95 0.08 0.13 0.33 0.33
OS2 OS2 0.288 12.05 12.05 12.05 0.20 0.20 0.25 2.05 3.50 7.16 0.12 0.20 0.51
0.51
Total Release from Site= 14.86
Intensity, I from Fig. RA-2
Rational Equation: Q = CiA (Equation 6-1)
Design
Point Basin Area
(ac.)
Runoff CTc (Min)Total Release from
Basin (cfs)
PROPOSED DIRECT RUNOFF COMPUTATIONS
Intensity (in/hr) Flow (cfs)
Johnson Drive Apartments
S. Thomas
December 18, 2019
Overland Flow, Time of Concentration:
Project:
Tc = Ti + Tt (Equation 6-2)
Tt = L / 60V (Equation 6-4)
Gutter/Swale Flow, Time of Concentration:Calculations By:
Date:
Velocity (Swale Flow), V = 15·S½
Velocity (Gutter Flow), V = 20·S½
(Equation 6-4)
(Equation 6-3)
}
𝑇 =1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ଵ ଷൗ
Page 1 of 1
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 – Storm Sewers
B.2 – Sidewalk Chase
B.3 – Detention Facilities
APPENDIX B.1
STORM SEWERS
Hydraflow Storm Sewers Extension for Autodesk0 Civil 3D0 Plan
Outfall
1
4
2
3
Project File: Storm A.stm Number of lines:4 Date: 12/16/2019
Storm Sewers v2019 20
Storm Sewer Summary Report Page1
Line Line ID Flow Line Line Line Invert Invert Line HGL HGL Minor HGL Dns Junction
No. rate Size shape length EL Dn EL Up Slope Down Up loss Junct Line Type
(cfs) (in) (ft) (ft) (ft) (%) (ft) (ft) (ft) (ft) No.
1 Pipe-(23) 11.39 18 Cir 144.568 4981.20 4982.66 1.010 4982.49 4983.95 n/a 4983.95 j End Manhole
2 Pipe-(20)(1) 10.50 18 Cir 114.757 4983.03 4983.20 0.148 4984.53' 4985.51` 0.08 4985.59 1 None
3 Pipe-(24) 10.50 18 Cir 65.319 4983.20 4984.00 1.224 4985.59* 4986.15" 0.55 4986.70 2 None
4 Pipe-(31) 0.89 12 Cir 28.917 4982.66 4982.80 0.483 4983.95' 4983.96` 0.02 4983.98 1 Generic
Project File: Storm A.stm Number of lines:4 Run Date: 12/17/2019
NOTES: Return period= 100 Yrs. ;"Surcharged(HGL above crown). ;j-Line contains hyd.jump.
Srorm Sewers v2019 20
Storm Sewer Tabulation Page1
Station Len Drng Area Rnoff Area x C Tc Rain Total Cap el Pipe Invert Elev HGL Elev Grnd/Rim Elev Line ID
coeff (I) flow full
Line To Incr Total Incr Total Inlet Syst Size Slope Dn Up Dn Up Dn Up
Line
(ft) (ac) (ac) (C) (min) (min) (in/hr) {cfs) (cfs) (ft/s) (in) (%) (ft) (ft) (ft) (ft) (ft) (ft)
1 End 144.568 0.00 0.00 0.00 0.00 0.00 0.0 0.5 0.0 11.39 11.43 7.05 18 1.01 4981.20 4982.66 4982.49 4983.95 4983.00 4987.12 Pipe-(23)
2 1 114.757 0.00 0.00 0.00 0.00 0.00 0.0 0.2 0.0 10.50 4.38 5.94 18 0.15 4983.03 4983.20 4984.53 4985.51 4987.12 4987.00 Pipe-(20)(1)
3 2 65.319 0.00 0.00 0.00 0.00 0.00 0.0 0.0 0.0 10.50 12.59 5.94 18 1.22 4983.20 4984.00 4985.59 4986.15 4987.00 4989.00 Pipe-(24)
4 1 28.917 0.00 0.00 0.00 0.00 0.00 0.0 0.0 0.0 0.89 2.68 1.13 12 0.48 4982.66 4982.80 4983.95 4983.96 4987.12 4986.92 Pipe-(31)
Project File: Storm A.stm Number of lines:4 Run Date: 12/17/2019
NOTES:Intensity= 127.16/(Inlet time+ 17.80)^0.82; Return period=Yrs. 100 : c=cir e=ellip b=box
Srorm Sewers v2019 20
Sto rm Sewe r P rof i l e Proj. file: Storm A.stm
@ � N M
7 7 7
j o � � O� � oO� J oO
O � O NCOM �00 �O
� � N � {(00 �..� �NN � �O
O � �- Cp nNM N �MM � Q�V
p � a0 � �W CO M �00 N (p �00
�
Elev. (ft) o w � v ��� � w�� N w�
O -a W + w W W N -a W W ch -a W
� E > � � » m E > > � E >
� � c � � c c � � c c � � c
4998.00 4998.00
4994.00 4994.00
4990.00 4990.00
�
-----^
4986.00 — _--- -- 4986.00
-------- � .
7Lf 18 0
4982.00 — 4982.00
i!.8"�a?�_
4978.00 4978.00
0 25 50 75 100 125 150 175 200 225 250 275 300 325
HGL EGL Reach (ft)
Storm Sewers
Sto rm Sewe r P rof i l e Proj. file: Storm A.stm
�
� �
o= = o
J
N CO CO N O
� �� ' ��
�
O r N N �N
O � 00 00 6] �o�
Elev. (ft) o � �� N ��
owww o ww
m E > > m E >
(n � � � !n � c
4995.00 —4995.00
4992.00 4992.00
4989.00 — I 4989.00
,. . I.
II I. I
4986.00 —4986.00
�
4983.00 —4983.00
�
4980.00 4980.00
0 10 20 30 40 50 60 70 80 90 100
HGL EGL Reach (ft)
Storm Sewers
Johnson Apartments
Project:1285-001
Date:
Calculation by:SJT
Circular
D or Da,
Pipe
Diameter
(ft)
H or Ha,
Culvert
Height
(ft)
W,
Culvert
Width
(ft)
Yt/D Q/D1.5 Q/D2.5 Yt/H Q/WH0.5
Storm A 11.39 1 10.50 1.50 0.60 0.40 5.72 3.81 N/A N/A 3.84 3.81 1.91 6.46 Type L 7.00 8.00 1.5
Spec
Length
of
Riprap
(ft)
Urban Drainage
pg MD-107
Design
Discharge
(cfs)
INPUT CALCULATE
At=Q/V
(ft2)
Number of
Barrels
Yt,
Tailwater
Depth
(ft)
Riprap
Type
(From
Figure
MD-21 or
MD-22)
Box CulvertFlow
through
each
Barrel (cfs)
L=
1/(2tanq)*
[At/Yt)-W]
(ft)
Culvert Parameters
CALCULATIONS FOR RIPRAP PROTECTION AT PIPE OUTLETS
Circular
Pipe
(Figure MD-21)
Rectangular
Pipe
(Figure MD-22)Spec
Width
of
Riprap
(ft)
2*d50,
Depth
of
Riprap
(ft)
for L/2
Froude
Parameter
Q/D2.5
Max 6.0
or
Q/WH1.5
Max 8.0
Expansion
Factor
1/(2tanq)
(From
Figure
MD-23 or
MD-24)
November 16, 2019
OUTPUT
Storm Line/Culvert
Label
APPENDIX B.2
SIDEWALK CHASE
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Saturday, Nov 16 2019
2' SIDEWALK CHASE
Rectangular
Bottom Width (ft) = 2.00
Total Depth (ft) = 0.50
Invert Elev (ft) = 1.00
Slope (%) = 0.50
N-Value = 0.012
Calculations
Compute by: Known Depth
Known Depth (ft) = 0.40
Highlighted
Depth (ft) = 0.40
Q (cfs) = 3.038
Area (sqft) = 0.80
Velocity (ft/s) = 3.80
Wetted Perim (ft) = 2.80
Crit Depth, Yc (ft) = 0.42
Top Width (ft) = 2.00
EGL (ft) = 0.62
0 .5 1 1.5 2 2.5 3
Elev (ft) Depth (ft)Section
0.75 -0.25
1.00 0.00
1.25 0.25
1.50 0.50
1.75 0.75
2.00 1.00
Reach (ft)
APPENDIX B.3
DETENTION FACILITIES
Pond No :
A1
100-yr
1.00
5.00 min 3500 ft3
1.67 acres 0.080 ac-ft
Max Release Rate =10.50 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 4985 1.00 10.50 3150 1835
10 7.720 7735 0.75 7.88 4725 3010
15 6.520 9800 0.67 7.00 6300 3500
20 5.600 11222 0.63 6.56 7875 3347
25 4.980 12475 0.60 6.30 9450 3025
30 4.520 13587 0.58 6.13 11025 2562
35 4.080 14309 0.57 6.00 12600 1709
40 3.740 14990 0.56 5.91 14175 815
45 3.460 15601 0.56 5.83 15750 -149
50 3.230 16182 0.55 5.78 17325 -1143
55 3.030 16698 0.55 5.73 18900 -2202
60 2.860 17194 0.54 5.69 20475 -3281
65 2.720 17715 0.54 5.65 22050 -4335
70 2.590 18166 0.54 5.63 23625 -5459
75 2.480 18637 0.53 5.60 25200 -6563
80 2.380 19078 0.53 5.58 26775 -7697
85 2.290 19504 0.53 5.56 28350 -8846
90 2.210 19930 0.53 5.54 29925 -9995
95 2.130 20275 0.53 5.53 31500 -11225
100 2.060 20641 0.53 5.51 33075 -12434
105 2.000 21042 0.52 5.50 34650 -13608
110 1.940 21383 0.52 5.49 36225 -14842
115 1.890 21778 0.52 5.48 37800 -16022
120 1.840 22124 0.52 5.47 39375 -17251
*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
1285-001
Johnson Drive Apartments
Project Number :
Project Name :
Pond A1
Page 1 of 1
1285-001_Pond A1_DetentionVolume_FAAModified Method.xls
S
E
E
E
E
E
E
E E
E
E
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0
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.
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0
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.
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.
7
0
8
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.
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.
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.
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EMERGENCY OVERFLOW WEIR
12' X 12" DEEP
INVERT ELEV: 4989.20
ACCESS GATE
SILL ELEV: 4990.00
18" RCP PIPE OUTFALL
INV. 4984.00
INSTALL 100-YR RESTRICTOR PLATE
4"
PERFORATED
PIPE
C.O.
C.O.C.O.
C.O.
C.O.
0.
8
%
0.
8
%
0.
8
%
ROOF DOWN SPOUTS
ROOF DOWN SPOUTS
CONCRETE FOREBAY
WEEP HOLES AT BASE
(RE:ARCH)
FOREBAY
OVERFLOW
WEIR
FOREBAY
OVERFLOW
WEIR
SAND FILTER
CHAMBER
TOP OF FILTER
MATERIAL: 4987.17
WQCV: 2,728 CF
0.
9
%
FLOOD OPENINGS
IN GARAGE WALL
8
8
.
5
0
88.50 8
8
.
5
0
STORMWATER TO
OVERFLOW WEIR
INTO DETENTION
CHAMBER 88.70
A A
B
B
100-YR DETENTION
CHAMBER
100-YR VOL: 3,500 CF
100-YR WSEL: 4987.42
ACCESS RAMP
INSTALL TRASH
RACK (RE: ARCH)
CONCRETE FOREBAY
WEEP HOLES AT BASE
(RE:ARCH)
NOTE:
- REFER TO STRUCTURAL PLANS FOR ADDITIONAL VAULT INFORMATION
SAND FILTER MATERIAL
(18" DEPTH)
RESERVOIR AGGREGATE
(8" DEPTH MINIMUM)
CONCRETE SLAB
RE: ARCH
4" PERFORATED UNDERDRAIN
4"
CLEANOUT
WQCV WSEL= 4988.67 (1.5' DEPTH)100-YR WSEL = 4987.42
OVERFLOW
WEIR TO
DETENTION
CHAMBER
ELEV. 4988.70
EMERGENCY
OVERFLOW WEIR
12' LONG X12" DEEP
INV. 4989.2
18" OUTFALL
INV. 4984.00 APPROXIMATE
GARAGE
SLAB
4989.00
APPROXIMATE
GARAGE
SLAB
4989.50
ACCESS SILL
ELEV. 4990.00
33.00'17.81'
UNDERDRAIN TO DISCHARGE
THROUGH WALL TO DETENTION CHAMBER CONCRETE SLAB
RE: ARCH
ACCESS SILL
ELEV. 4990.00
EMERGENCY
OVERFLOW WEIR
12' LONG X12" DEEP
INV. 4989.2OVERFLOW
WEIR TO
DETENTION
CHAMBER
ELEV. 4988.70
4" PERFORATED
UNDERDRAIN
SAND FILTER MATERIAL
(18" DEPTH)
RESERVOIR AGGREGATE
(8" DEPTH MINIMUM)
APPROX.
GARAGE
SLAB
4989.00
PERMEABLE
GEOTEXTILE FABRIC
62.00'
TOP OF FILTER MATERIAL = 4987.17
ACCESS
RAMP
RE:ARCH
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18
100 YEAR ORIFICE PLATE SUMMARY
POND INV. ELEV.
100-YEAR ORIFICE PLATE503
1.CONTRACTOR SHALL INSTALL SAND FILTER BASINS ACCORDING TO THE APPROVED PLANS
AND/OR CONSTRUCTION SPECIFICATIONS.
2.PRE-CONSTRUCTION
2.1.CONTRACTOR SHALL AVOID COMPACTION OF THE SAND FILTER BASIN AREA TO PRESERVE
EXISTING INFILTRATION RATES.
2.2.CONTRACTOR SHALL CALL FOR CITY INSPECTIONS AT THE INTERVALS STIPULATED IN THE
"DURING CONSTRUCTION INSPECTION CHECKLISTS".
3.DURING CONSTRUCTION:
3.1.CONTRACTOR SHALL PROVIDE CONSTRUCTION OBSERVATION DURING CONSTRUCTION OF
THE SAND FILTER BASIN TO ENSURE COMPLIANCE WITH THE APPROVED PLANS AND
DESIGN SPECIFICATIONS.
3.2.LOOSE MATERIALS SHALL NOT BE STORED ON THE SAND FILTER BASIN AREA.
3.3.THE CONTRACTOR SHALL, AT ALL TIMES DURING AND AFTER SYSTEM INSTALLATION,
PREVENT SEDIMENT, DEBRIS AND DIRT FROM ANY SOURCE FROM ENTERING THE SAND
FILTER SYSTEM.
4.GEOTEXTILE LINERS:
4.1.GEOTEXTILE LINERS (PERMEABLE OR IMPERMEABLE AS PER PLAN) MAY BE INSTALLED
ALONG PERIMETER OF CROSS-SECTION OF THE SAND FILTER CELL.
4.2.PERMEABLE GEOTEXTILE LINER SHALL BE PLACED BELOW THE SAND LAYER IN THE SAND
FILTER CELL UNLESS THE ALTERNATIVE CROSS-SECTION IS PROVIDED.
4.3.WHERE USED, GEOTEXTILE LINERS SHALL BE PLACED IN ACCORDANCE WITH
MANUFACTURER'S STANDARDS AND RECOMMENDATIONS. ALL SEAMS AND OPENINGS IN
THE LINER SHALL BE SEALED ACCORDING TO MANUFACTURER'S RECOMMENDATIONS AND
SPECIFICATIONS.
4.4.WHERE USED, IMPERMEABLE GEOMEMBRANE SHEET / LINER SHALL BE 40 MIL THICK,
HIGH-DENSITY POLYETHYLENE DESIGNED SPECIFICALLY FOR FLEXIBLE GEOMEMBRANE
APPLICATIONS. ADJACENT STRIPS OF IMPERMEABLE LINER SHALL OVERLAP A MINIMUM OF
18", OR PER MANUFACTURER'S SPECIFICATION.
4.5.WHERE USED, CONTRACTOR TO PLACE LINER IN A WAY THAT ENSURES ENOUGH SLACK IN
THE LINER TO ALLOW FOR BACKFILL AND SETTLING WITHOUT TEARING THE LINER.
5.AGGREGATES:
5.1.ALL AGGREGATES SHALL BE ANGULAR, CRUSHED, WASHED ROCK, CLEAN OF DEBRIS AND
WITH NO MORE THAN 1% FINES.
5.2.RESERVOIR AGGREGATE SHALL BE GRADATION ASTM #57 OR #67.
5.3.DIAPHRAGM AGGREGATE SHOWN IN ALTERNATIVE CROSS-SECTION SHALL BE "PEA
GRAVEL", WITH GRADATION ASTM #8, #89 OR #9.
5.4.SAND FILTER MATERIAL SHALL BE GRADATION ASTM C33 SAND.
6.UNDERDRAIN:
6.1.UNDERDRAIN PIPE TO BE PERFORATED OR SLOTTED. PERFORATIONS OR SLOTS TO BE
SMALLER THAN SURROUNDING AGGREGATE TO ENSURE AGGREGATE DOES NOT FALL INTO
OR CLOG THE OPENINGS.
6.2.DO NOT WRAP UNDERDRAIN WITH GEOTEXTILE OR SOCK.
6.3.UNDERDRAIN PIPE MUST OUTFALL BY GRAVITY AND MUST TIE INTO A STORMWATER PIPE,
INLET OR SYSTEM AND THE LOCATION MUST BE APPROVED BY THE CITY. THE UNDERDRAIN
TIE-IN SHALL MEET ALL REQUIRED PIPE SIZE, TYPES, AND COVER REQUIREMENTS THAT
MAY APPLY TO PIPING THAT EXTENDS BEYOND THE LIMITS OF THE SAND FILTER CELL AND
ENCROACHES INTO PUBLIC RIGHT-OF-WAY OR OTHER PROPERTY.
7.OVERFLOW INLET:
7.1.AN OVERFLOW INLET OR RISER PIPE SHALL BE PROVIDED.
7.2.ALL OVERFLOW RISER PIPE SHALL BE CAPPED WITH A DOME-SHAPED GRATE.
7.3.AN EMERGENCY OVERFLOW ROUTE SHALL BE PROVIDED AND THE LOCATION SHALL BE
IDENTIFIED ON THE PLANS.
8.CLEANOUTS:
8.1.PROVIDE CLEANOUTS (AS PER PLAN) TO ALLOW INSPECTION (BY CAMERA) OF THE
UNDERDRAIN SYSTEM DURING AND AFTER CONSTRUCTION.
8.2.CLEANOUTS SHALL BE PROVIDED AT EACH BEND GREATER THAN OR EQUAL TO 90° AND
EVERY 100' ALONG A STRAIGHT RUN. CLEANOUT SHALL BE INSTALLED PER THE APPROVED
PLANS.
8.3.CLEANOUTS SHALL BE A SOLID WALL PVC STRUCTURE FOR ALL VERTICAL SECTIONS WITH
FITTINGS TO CONNECT TO DISTRIBUTION AND UNDERDRAIN PIPING MATERIALS, AS
REQUIRED.
9.FOREBAY:
9.1.THE FOREBAY SHALL BE EASILY ACCESSIBLE WITH A HARD SURFACED BOTTOM FOR
MAINTENANCE PURPOSES.
10.LANDSCAPE MATERIALS
10.1.CONTRACTOR SHALL NOT PLACE WEED BARRIER ANYWHERE WITHIN THE SAND FILTER
BASIN. IF MULCH IS PLACED IN THE SAND FILTER BASIN, IT MUST BE NON-FLOATABLE.
10.2.IF MULCH OR COBBLES ARE PLACED IN THE SAND FILTER BASIN, THE MAXIMUM
ALLOWABLE WATER DEPTH OF 36" AND REQUIRED BASIN VOLUME MUST BE MEASURED
FROM THE TOP SURFACE OF THE MULCH OR COBBLE.
10.3.ROLLED TURF OR SOD IS NOT AN ALLOWABLE LANDSCAPE MATERIAL FOR SAND FILTER
BASINS.
10.4.LANDSCAPE MATERIALS ARE GENERALLY NOT ENCOURAGED TO BE PLACED ON THE
BOTTOM OF THE SAND FILTER BASIN. LANDSCAPE PLANTINGS SHALL NOT BE PLACED TO
IMPEDE DRAINAGE INTO OR OUT OF THE SAND FILTER BASIN.
10.5.TEMPORARY IRRIGATION MAY BE INSTALLED TO ESTABLISH LANDSCAPING OR SEED IN
THE SAND FILTER BASIN.
NOTES:
8" MIN 4" MIN DIAMETER
PERFORATED PVC
UNDERDRAIN
2" MIN
GEOTEXTILE LINER
OPTION (AS PER PLAN)
1
MAXIMUM ALLOWABLE
PONDING DEPTH IS 36"
FROM THE TOP OF THE
MULCH
4 MAX
NON-FLOATABLE
MULCH (AS PER
PLAN)
3"
PONDING DEPTH MUST
NOT EXCEED FLOWLINE
ELEVATION OF ADJACENT
GUTTER
FOREBAY IS REQUIRED TO
BE PLACED AT ALL INFLOW
LOCATIONS; WITH A
MINIMUM 3" DROP FROM
GUTTER FLOWLINE TO
FOREBAY
8" MIN DEPTH OF
RESERVOIR AGGREGATE
18" MIN DEPTH OF
SAND FILTER MATERIAL
8" MIN DEPTH THICKENED
CURB ADJACENT TO
VEHICULAR PAVEMENTS
STANDARD CROSS-SECTION
8"
PERMEABLE GEOTEXTILE
TO BE PLACED BETWEEN
AGGREGATE LAYERS NATIVE SOIL
ZONE
OVERFLOW
RISER OPTION
(AS PER PLAN)
36" MAX
26" MIN 18"
8"
4"
30" MIN
PONDING DEPTH
ALTERNATIVE
CROSS-SECTION
8" MIN DEPTH OF
RESERVOIR AGGREGATE
18" MIN DEPTH OF
SAND FILTER MATERIAL
4" MIN DEPTH OF
DIAPHRAGM AGGREGATE
NOTE:THE ALTERNATIVE CROSS-SECTIONS SHOWS A 4"
DIAPHRAGM AGGREGATE LAYER INSTEAD OF THE
GEOTEXTILE FABRIC, WHICH IS THE ONLY DIFFERENCE FROM
THE STANDARD CROSS-SECTION. ALL OTHER REQUIREMENTS
OF THE STANDARD CROSS-SECTION ARE REQUIRED.
18" MIN
FLAT
APPROVED:
DRAWN BY:DETAILS
CONSTRUCTION DATE REVISED:
DETAILSTORMWATER
SAND FILTER
DECEMBER 2018
HEM
D-55
ORIFICE OPENING
PLATE CENTERED
OVER PIPE OPENING
IN WALL
12" Ø HOLES FOR
3 8" Ø EXPANSION BOLTS
EMBEDDING 2" INTO
CONCRETE WALL @
6" O.C. MIN.
5 16" THICK
GALVANIZED
STEEL PLATE D
D+4"
D+4"
ORIFICE INVERT SHALL MATCH
PIPE INVERT
18" RCPD
120°
90°
60°
A
SCREEN SLOT TABLE
A B C D E F
PIPE SIZE ROWS OF
SLOTS
SLOT
LENGTH
MAXIMUM
SLOT WIDTH
APPROX.
SLOT/ROW
PER FOOT
APPROX.
SLOT
SPACING
OPEN AREA
PER FOOT
4"3 (MIN.) - 6 (MAX.)1.06"-1.50"0.032"14 1/2"-3/4"1.90-3.15 SQ. IN.
NOTES:
1."SLOTTED HDPE" AND "PERFORATED HDPE" SHALL MEAN THE SAME THING WHEN
REFERRING TO UNDERDRAINS IN THIS PLAN SET.
2.ALTERNATE SLOT DIMENSIONS AND PERFORATIONS REQUIRE EXPLICIT APPROVAL OF THE
ENGINEER.
DIMENSIONS FOR PERFORATED HDPE PIPE504
DETENTION AND SAND FILTER CHAMBER SCHEMATIC500
SECTION B-B502SECTION A-A501
NOTES:
1.SEE NOTES ON CITY OF FORT COLLINS SAND FILTER DETAIL ABOVE.
2.REFER TO ARCHITECTURAL PLANS FOR CONSTRUCTION OF DETENTION AND SAND FILTER
VAULT.
(REFER TO ARCHITECTURAL PLANS FOR
CONSTRUCTION OF CHAMBERS)
1.ALL CURB SPOTS SHOWN ARE FLOWLINE ELEVATIONS. ALL OTHER SPOTS ARE FINISHED GRADE
ELEVATIONS.
2.ALL PROJECT DATA IS ON THE CITY OF FORT COLLINS VERTICAL DATUM NAVD88. SEE COVER SHEET
FOR BENCHMARK REFERENCES..
3.ADD 4900-FT TO PROPOSED CONTOURS, SPOT ELEVATIONS, AND FFE LABELS, WHERE TRUNCATED.
4.CONTRACTOR SHALL CONFIRM AND COORDINATE WITH ARCHITECTURAL DRAWINGS FOR DETAILS
OF RAILINGS, TRASH RACK, FOREBAYS CONSTRUCTION, STRUCTURAL REINFORCEMENT AND
CONSTRUCTION OF VAULT, ACCESS GATES, ROOF DOWN SPOUTS, ETC. NOTIFY OWNER,
ARCHITECT, AND ENGINEER(S) OF ANY DISCREPANCIES PRIOR TO MOBILIZATION.
5.ALL PIPE PENETRATIONS THROUGH CONCRETE WALLS SHALL HAVE WATERTIGHT SEAL.
6.REFER TO STRUCTURAL/ARCHITECTURAL PLANS FOR CONCRETE WATER-PROOFING TREATMENT
REQUIREMENTS IN DETENTION VAULT.
NOTES:
Sand Filter - Water Quality Vault
Area of Vault = 1917.7 SF
Sand Leveled to Elevation = 4987.17
Minimum Depth of Sand Material= 26 INCHES
Volume of WQ Provided (1.5' Deep)= 2876.5 CF
Volume of WQ Required = 2,728 CF
WQCV Elevation = 4990.67
100-yr Detention Vault
Area of Vault = 1105.67 SF
Average Depth = 4.45 FT
100-yr Volume Provided = 4,914.00 CF
100-yr Volume Required= 3,500.00 CF
100-yr Det Elev = 4987.42
M
O
D
E
3
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T
U
R
E
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E
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Y
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Johnson Drive Apartments
ORIFICE RATING CURVE
100-yr Detention in Building
100-yr Orifice
Project:Johnson Drive
Date:12/17/2019
By:S. Thomas
100-yr WSEL=4987.42
Orifice Plate
Outflow Q 10.5 cfs
Orifice Coefficient Cd 0.65
Gravity Constant g 32.2 ft/s^2
100-year head H 3.42 ft
Orifice Area Ao 1.09 ft^2
Orifice Area Ao 156.74 in^2
Radius r 7.1 in
Diameter d 14.1 in
Orifice Curve
Stage (ft)H (ft) Q (cfs) SWMM Stage Note
4984.00 0.00 0.00 0.00 Pond Invert
4984.50 0.50 4.01 0.50
4985.00 1.00 5.68 1.00
4985.50 1.50 6.95 1.50
4986.00 2.00 8.03 2.00
4986.50 2.50 8.98 2.50
4987.00 3.00 9.83 3.00
4987.42 3.42 10.50 3.42 100-yr WSEL
4988.12 4.12 11.52 4.12 Emergency Overflow
12/17/2019 5:20 PM D:\Projects\1285-001\Drainage\Detention\1285-001_Pond A1 - 100 yr Restrictor.xlsx\Orifice Size
Weir Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, Nov 19 2019
Emergency Spill from Detention Pond A1
Rectangular Weir
Crest = Sharp
Bottom Length (ft) = 12.00
Total Depth (ft) = 1.00
Calculations
Weir Coeff. Cw = 3.33
Compute by: Known Q
Known Q (cfs) = 16.62
Highlighted
Depth (ft) = 0.56
Q (cfs) = 16.62
Area (sqft) = 6.68
Velocity (ft/s) = 2.49
Top Width (ft) = 12.00
0 2 4 6 8 10 12 14 16
Depth (ft) Depth (ft)Emergency Spill from Detention Pond A1
-0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
1.50 1.50
2.00 2.00
Length (ft)Weir W.S.
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, Dec 17 2019
Overflow Path in Garage
User-defined
Invert Elev (ft) = 1.00
Slope (%) = 0.90
N-Value = 0.012
Calculations
Compute by: Known Q
Known Q (cfs) = 16.62
(Sta, El, n)-(Sta, El, n)...
( 0.00, 1.30)-(17.50, 1.00, 0.012)-(18.50, 1.00, 0.012)-(36.00, 1.30, 0.012)
Highlighted
Depth (ft) = 0.29
Q (cfs) = 16.62
Area (sqft) = 5.20
Velocity (ft/s) = 3.20
Wetted Perim (ft) = 34.84
Crit Depth, Yc (ft) = 0.30
Top Width (ft) = 34.83
EGL (ft) = 0.45
-5 0 5 10 15 20 25 30 35 40 45
Elev (ft) Depth (ft)Section
0.75 -0.25
1.00 0.00
1.25 0.25
1.50 0.50
1.75 0.75
2.00 1.00
Sta (ft)
APPENDIX C
WATER QUALITY DESIGN COMPUTATIONS
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =100.0 %
(100% if all paved and roofed areas upstream of sand filter)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 1.000
C) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 0.45 watershed inches
WQCV= 0.9 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including sand filter area) Area = 72,754 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =2,728 cu ft
VWQCV = WQCV / 12 * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 =0.43 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =2,728 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth DWQCV =1.5 ft
B) Sand Filter Side Slopes (Horizontal distance per unit vertical, Z = 0.00 ft / ft
4:1 or flatter preferred). Use "0" if sand filter has vertical walls.
C) Mimimum Filter Area (Flat Surface Area)AMin =606 sq ft
D) Actual Filter Area AActual =1917 sq ft
E) Volume Provided VT =2876 cu ft
3. Filter Material
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =1.0 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =2,728 cu ft
iii) Orifice Diameter, 3/8" Minimum DO =1 - 3 / 8 in
Johnson Drive Apartments - Basin A1
Fort Collins, CO
Design Procedure Form: Sand Filter (SF)
Cody Snowdon
Northern Engineering
December 16, 2019
Choose One
Choose One
18" CDOT Class C Filter Material
Other (Explain):
YES
NO
WQ - Basin A1 - UD-BMP_v3.03.xlsm, SF 12/16/2019, 3:35 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
PROVIDE A 30 MIL (MIN) PVC GEOMEMBRANE PER TABLE
SF-4 WITH SEPARATOR FABRIC (PER TABLE SF-3) ABOVE IT.
PROVIDE SEPARATOR FABRIC BELOW THE GEOMEMBRANE
AS WELL IF SUBGRADE IS ANGULAR OR COULD OTHERWISE
PUNCTURE THE GEOMEMBRANE.
6-7. Inlet / Outlet Works
A) Describe the type of energy dissipation at inlet points and means of
conveying flows in excess of the WQCV through the outlet
Notes:
Design Procedure Form: Sand Filter (SF)
Cody Snowdon
Northern Engineering
December 16, 2019
Johnson Drive Apartments - Basin A1
Fort Collins, CO
Choose One
YES NO
WQ - Basin A1 - UD-BMP_v3.03.xlsm, SF 12/16/2019, 3:35 PM
APPENDIX D
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 C0.01 and C3.00 of the Utility Plans.
The Utility Plans will also contain a full-size Erosion Control Plan, as well as a separate sheet
dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the
Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing
Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior
to issuance of the Development Construction Permit. Also, the Site Contractor for this project 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
SOIL 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
Area, Colorado
Next Chapter Student Housing
Natural
Resources
Conservation
Service
August 24, 2017
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface....................................................................................................................2
How Soil Surveys Are Made..................................................................................5
Soil Map.................................................................................................................. 8
Soil Map................................................................................................................9
Legend................................................................................................................10
Map Unit Legend................................................................................................ 11
Map Unit Descriptions.........................................................................................11
Larimer County Area, Colorado......................................................................13
3—Altvan-Satanta loams, 0 to 3 percent slopes.........................................13
53—Kim loam, 1 to 3 percent slopes.......................................................... 15
Soil Information for All Uses...............................................................................17
Soil Properties and Qualities..............................................................................17
Soil Erosion Factors........................................................................................17
Wind Erodibility Group (Next Chapter Student Housing)............................ 17
Wind Erodibility Index (Next Chapter Student Housing)..............................20
Soil Qualities and Features.............................................................................23
Hydrologic Soil Group (Next Chapter Student Housing).............................23
References............................................................................................................28
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
Custom Soil Resource Report
6
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
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Custom Soil Resource Report
Soil Map
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 45 90 180 270
Feet
0 10 20 40 60
Meters
Map Scale: 1:932 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 20, 2015—Oct
15, 2016
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
10
Map Unit Legend
Larimer County Area, Colorado (CO644)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
3 Altvan-Satanta loams, 0 to 3
percent slopes
2.6 99.4%
53 Kim loam, 1 to 3 percent slopes 0.0 0.6%
Totals for Area of Interest 2.6 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
Custom Soil Resource Report
11
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
12
Larimer County Area, Colorado
3—Altvan-Satanta loams, 0 to 3 percent slopes
Map Unit Setting
National map unit symbol: jpw2
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: Prime farmland if irrigated
Map Unit Composition
Altvan and similar soils: 45 percent
Satanta and similar soils: 30 percent
Minor components: 25 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Altvan
Setting
Landform: Benches, terraces
Landform position (three-dimensional): Side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 18 inches: clay loam, loam, sandy clay loam
H2 - 10 to 18 inches: loam, fine sandy loam, silt loam
H2 - 10 to 18 inches: gravelly sand, gravelly coarse sand, coarse sand
H3 - 18 to 30 inches:
H3 - 18 to 30 inches:
H3 - 18 to 30 inches:
H4 - 30 to 60 inches:
H4 - 30 to 60 inches:
H4 - 30 to 60 inches:
Properties and qualities
Slope: 0 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
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 13.2 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 3e
Custom Soil Resource Report
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Hydrologic Soil Group: B
Hydric soil rating: No
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 18 inches: loam, clay loam, sandy clay loam
H2 - 9 to 18 inches: loam, clay loam, fine sandy loam
H2 - 9 to 18 inches:
H3 - 18 to 60 inches:
H3 - 18 to 60 inches:
H3 - 18 to 60 inches:
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
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): 1
Land capability classification (nonirrigated): 3c
Hydrologic Soil Group: B
Hydric soil rating: No
Minor Components
Nunn
Percent of map unit: 10 percent
Hydric soil rating: No
Larim
Percent of map unit: 10 percent
Hydric soil rating: No
Stoneham
Percent of map unit: 5 percent
Hydric soil rating: No
Custom Soil Resource Report
14
53—Kim loam, 1 to 3 percent slopes
Map Unit Setting
National map unit symbol: jpwx
Elevation: 4,800 to 5,600 feet
Mean annual precipitation: 13 to 15 inches
Mean annual air temperature: 48 to 50 degrees F
Frost-free period: 135 to 150 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Kim and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Kim
Setting
Landform: Fans
Landform position (three-dimensional): Base slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 7 inches: loam
H2 - 7 to 60 inches: loam, clay loam, sandy clay loam
H2 - 7 to 60 inches:
H2 - 7 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: Low
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: 15 percent
Salinity, maximum in profile: Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm)
Available water storage in profile: Very high (about 26.5 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: B
Ecological site: Loamy Plains (R067XY002CO)
Custom Soil Resource Report
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Hydric soil rating: No
Minor Components
Fort collins
Percent of map unit: 6 percent
Hydric soil rating: No
Stoneham
Percent of map unit: 3 percent
Hydric soil rating: No
Aquic haplustolls
Percent of map unit: 1 percent
Landform: Swales
Hydric soil rating: Yes
Custom Soil Resource Report
16
Soil Information for All Uses
Soil Properties and Qualities
The Soil Properties and Qualities section includes various soil properties and
qualities displayed as thematic maps with a summary table for the soil map units in
the selected area of interest. A single value or rating for each map unit is generated
by aggregating the interpretive ratings of individual map unit components. This
aggregation process is defined for each property or quality.
Soil Erosion Factors
Soil Erosion Factors are soil properties and interpretations used in evaluating the
soil for potential erosion. Example soil erosion factors can include K factor for the
whole soil or on a rock free basis, T factor, wind erodibility group and wind erodibility
index.
Wind Erodibility Group (Next Chapter Student Housing)
A wind erodibility group (WEG) consists of soils that have similar properties
affecting their susceptibility to wind erosion in cultivated areas. The soils assigned
to group 1 are the most susceptible to wind erosion, and those assigned to group 8
are the least susceptible.
17
18
Custom Soil Resource Report
Map—Wind Erodibility Group (Next Chapter Student Housing)
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 45 90 180 270
Feet
0 10 20 40 60
Meters
Map Scale: 1:932 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Lines
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Points
1
2
3
4
4L
5
6
7
8
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 20, 2015—Oct
15, 2016
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
19
Table—Wind Erodibility Group (Next Chapter Student Housing)
Wind Erodibility Group— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
3 Altvan-Satanta loams, 0
to 3 percent slopes
5 2.6 99.4%
53 Kim loam, 1 to 3 percent
slopes
4L 0.0 0.6%
Totals for Area of Interest 2.6 100.0%
Rating Options—Wind Erodibility Group (Next Chapter Student
Housing)
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Lower
Wind Erodibility Index (Next Chapter Student Housing)
The wind erodibility index is a numerical value indicating the susceptibility of soil to
wind erosion, or the tons per acre per year that can be expected to be lost to wind
erosion. There is a close correlation between wind erosion and the texture of the
surface layer, the size and durability of surface clods, rock fragments, organic
matter, and a calcareous reaction. Soil moisture and frozen soil layers also
influence wind erosion.
Custom Soil Resource Report
20
21
Custom Soil Resource Report
Map—Wind Erodibility Index (Next Chapter Student Housing)
44
9
0
0
2
0
44
9
0
0
4
0
44
9
0
0
6
0
44
9
0
0
8
0
44
9
0
1
0
0
44
9
0
1
2
0
44
9
0
1
4
0
44
9
0
0
2
0
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0
0
4
0
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0
0
6
0
44
9
0
0
8
0
44
9
0
1
0
0
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9
0
1
2
0
44
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0
1
4
0
493240 493260 493280 493300 493320 493340 493360 493380 493400 493420 493440
493240 493260 493280 493300 493320 493340 493360 493380 493400 493420 493440
40° 33' 43'' N
10
5
°
4
'
4
7
'
'
W
40° 33' 43'' N
10
5
°
4
'
3
8
'
'
W
40° 33' 39'' N
10
5
°
4
'
4
7
'
'
W
40° 33' 39'' N
10
5
°
4
'
3
8
'
'
W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 45 90 180 270
Feet
0 10 20 40 60
Meters
Map Scale: 1:932 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Lines
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Points
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 20, 2015—Oct
15, 2016
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
22
Table—Wind Erodibility Index (Next Chapter Student Housing)
Wind Erodibility Index— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating (tons per acre
per year)
Acres in AOI Percent of AOI
3 Altvan-Satanta loams, 0
to 3 percent slopes
56 2.6 99.4%
53 Kim loam, 1 to 3 percent
slopes
86 0.0 0.6%
Totals for Area of Interest 2.6 100.0%
Rating Options—Wind Erodibility Index (Next Chapter Student
Housing)
Units of Measure: tons per acre per year
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Soil Qualities and Features
Soil qualities are behavior and performance attributes that are not directly
measured, but are inferred from observations of dynamic conditions and from soil
properties. Example soil qualities include natural drainage, and frost action. Soil
features are attributes that are not directly part of the soil. Example soil features
include slope and depth to restrictive layer. These features can greatly impact the
use and management of the soil.
Hydrologic Soil Group (Next Chapter Student Housing)
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive precipitation
from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly
wet. These consist mainly of deep, well drained to excessively drained sands or
gravelly sands. These soils have a high rate of water transmission.
Custom Soil Resource Report
23
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well drained
soils that have moderately fine texture to moderately coarse texture. These soils
have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of water
transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay layer at
or near the surface, and soils that are shallow over nearly impervious material.
These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in their
natural condition are in group D are assigned to dual classes.
Custom Soil Resource Report
24
25
Custom Soil Resource Report
Map—Hydrologic Soil Group (Next Chapter Student Housing)
44
9
0
0
2
0
44
9
0
0
4
0
44
9
0
0
6
0
44
9
0
0
8
0
44
9
0
1
0
0
44
9
0
1
2
0
44
9
0
1
4
0
44
9
0
0
2
0
44
9
0
0
4
0
44
9
0
0
6
0
44
9
0
0
8
0
44
9
0
1
0
0
44
9
0
1
2
0
44
9
0
1
4
0
493240 493260 493280 493300 493320 493340 493360 493380 493400 493420 493440
493240 493260 493280 493300 493320 493340 493360 493380 493400 493420 493440
40° 33' 43'' N
10
5
°
4
'
4
7
'
'
W
40° 33' 43'' N
10
5
°
4
'
3
8
'
'
W
40° 33' 39'' N
10
5
°
4
'
4
7
'
'
W
40° 33' 39'' N
10
5
°
4
'
3
8
'
'
W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 45 90 180 270
Feet
0 10 20 40 60
Meters
Map Scale: 1:932 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 20, 2015—Oct
15, 2016
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
26
Table—Hydrologic Soil Group (Next Chapter Student Housing)
Hydrologic Soil Group— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
3 Altvan-Satanta loams, 0
to 3 percent slopes
B 2.6 99.4%
53 Kim loam, 1 to 3 percent
slopes
B 0.0 0.6%
Totals for Area of Interest 2.6 100.0%
Rating Options—Hydrologic Soil Group (Next Chapter Student
Housing)
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Custom Soil Resource Report
27
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
28
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/soils/scientists/?cid=nrcs142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf
Custom Soil Resource Report
29
APPENDIX F
FEMA MAPPING
USGS The National Map: Orthoimagery. Data refreshed April, 2019.
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250Feet
Ü
105°5'1.81"W
40°33'56.85"N
105°4'24.35"W 40°33'29.52"N
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOODHAZARD AR EAS
Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or Depth Zone AE, AO, AH, VE, AR
Regulator y Floodway
0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone X
Future Conditions 1% AnnualChance Flood Hazard Zone XArea with Reduced Flood Risk due toLevee. See Notes.Zone X
Area with Flood Risk due to Levee Zone D
NO SCREE N Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood Hazard Zone D
Channel, Culver t, or Storm SewerLevee, Dike, or Floodwall
Cross Sections with 1% Annual Chance17.5 Water Surface ElevationCoastal Transect
Coastal Transect BaselineProfile BaselineHydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of StudyJurisdiction Boundar y
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards
The flood hazard information is derived directly from theauthoritative NFHL web ser vices provided by FEMA. This mapwas exported on 10/3/2019 at 7:06:21 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time.
This map image is void if the one or more of the following mapelements do not appear: basemap imagery, flood zone labels,legend, scale bar, map creation date, community identifiers,FIRM panel number, and FIRM effective date. Map images forunmapped and unmodernized areas cannot be used forregulatory purposes.
Legend
OTHER AREAS OFFLOOD HAZARD
OTHER AREAS
GENERALSTRUCTURES
OTHERFEATURES
MAP PANELS
8
1:6,000
B 20.2
The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative proper ty location.
SITE LOCATION
MAP PACKET
T
T
M
X
X
X
X
X
X
X
HY D
AC
B M
ELEC
CABLE
C
X
X X
X
X
X
X
X
X
X
X
TESTSTA
PH
PH
PH
PH
PH
PH
PH
HW1
hw1
he1
HE1
JOHNSON DRIVE
SP
R
I
N
G
C
O
U
R
T
BU
R
L
I
N
G
T
O
N
N
O
R
T
H
E
R
N
RA
I
L
W
A
Y
A
N
D
M
A
X
G
U
I
D
E
W
A
Y
PORTION OF LOT 3,
BANK CENTER SQUARE
hw1
HS1
EXISTING
CULVERT
D:
\
P
R
O
J
E
C
T
S
\
1
2
8
5
-
0
0
1
\
D
W
G
\
D
R
N
G
\
1
2
8
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0
0
1
H
I
S
T
-
E
X
H
I
B
I
T
.
D
W
G
JOHNSON DRIVE APARTMENTS
DESCRIPTION
HISTORIC DRAINAGE
EXHIBIT
DRAWN BY
S. THOMAS
DATE
11/15/2019
PROJECT
1285-001
EX-1
DRAWINGSCALE
1"=60'
FORT COLLINS: 301 North Howes Street, Suite 100, 80521
GREELEY: 820 8th Street, 80631
E N G I N E E R N GI
EHTRON R N
970.221.4158
northernengineering.com
GRAPHIC SCALE:
LEGEND:
EXISTING DECID. TREE
EXISTING CONIF. TREE
EXISTING LIGHT POLE
EXISTING STUMP
EXISTING OVERLAND FLOW DIRECTION
CONCENTRATED FLOW DIRECTION
A2
a3
DRAINAGE BASIN AREA
DRAINAGE BASIN ID
ASPHALT
DRAINAGE BASIN DESIGN POINT
( IN FEET )
0
1 INCH = 60 FEET
60 60
ROOF
CONCRETE
DRAINAGE BASIN MINOR/MAJOR COEFF.