HomeMy WebLinkAboutSAINT JOHN XXIII CATHOLIC CHURCH AND LOMBARDY STUDENT HOUSING - PDP190001 - SUBMITTAL DOCUMENTS - ROUND 2 - REVISIONSFebruary 6, 2019
PRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT FOR
SAINT JOHN XXIII
Fort Collins, Colorado
Prepared for:
Blackbird Investments, LLC
Des Moines, Iowa 50309
Prepared by:
301 N. Howes, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 1560-001
This Drainage Report is consciously provided as a PDF.
Please consider the environment before printing this document in its entirety.
When a hard copy is absolutely necessary, we recommend double-sided printing.
February 6, 2019
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage and Erosion Control Report for
SAINT JOHN XXIII
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report
for your review. This report accompanies the Final Plan submittal for the proposed “Saint John
XXIII” development.
This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM),
and serves to document the stormwater impacts associated with the proposed project. We
understand that review by the City is to assure general compliance with standardized criteria
contained in the FCSCM.
If you should have any questions as you review this report, please feel free to contact us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
Aaron Cvar, PhD, PE
Senior Project Engineer
Saint John XXIII
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 2
C. Floodplain.......................................................................................................................................... 4
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 5
A. Major Basin Description .................................................................................................................... 5
B. Sub-Basin Description ....................................................................................................................... 5
III. DRAINAGE DESIGN CRITERIA ................................................................................... 5
A. Regulations........................................................................................................................................ 5
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 6
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 7
F. Modifications of Criteria ................................................................................................................... 7
IV. DRAINAGE FACILITY DESIGN .................................................................................... 7
A. General Concept ............................................................................................................................... 7
B. Specific Details .................................................................................................................................. 8
V. CONCLUSIONS ........................................................................................................ 9
A. Compliance with Standards .............................................................................................................. 9
B. Drainage Concept .............................................................................................................................. 9
APPENDICES:
APPENDIX A – Hydrologic Computations, Historic Drainage Exhibit
APPENDIX B - USDA Soils Information
APPENDIX C – Water Quality Calculations, LID Information
APPENDIX D – Detention Calculations
APPENDIX E – Erosion Control Report
APPENDIX F – Current Effective FIRM Panel
LIST OF FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2– Proposed Site Plan ................................................................................................ 3
Figure 3 – Existing Floodplains ............................................................................................. 4
MAP POCKET:
Proposed Drainage Exhibit
Floodplain Exhibit
Saint John XXIII
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. The project site is located in the southwest quarter of 15, 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 just southwest of the intersection of South Shields St. and
West Elizabeth Street.
4. The project site lies within the Old Town Master Drainage Basin. Per the Old Town
Master Drainage Plan, onsite detention is required. Onsite detention is required for the
runoff volume difference between the 100-year developed inflow rate and the 2-year
historic release rate.
5. LID water quality treatment will be provided on site, as described in further detail
below.
6. As this is an infill site, much of the area surrounding the site is fully developed.
Saint John XXIII
Preliminary Drainage Report 2
7. Offsite flows enter the site from the north and west. We have accounted for these
offsite flows and will safely convey 100-year offsite flows through the site and
discharge flows into the adjacent Shields Street Right of Way. Offsite flows will be
treated as a “pass-through” design and will not be detained. We have defined two
offsite basins as shown in the Historic Drainage Exhibit provided in Appendix A.
Further discussion of these basins and flow quantities are provided below.
B. Description of Property
1. The development area is roughly 6.0 net acres.
Figure 1 – Aerial Photograph
2. The subject property is currently composed of existing buildings, and landscaped
areas. Existing ground slopes are mild to moderate (i.e., 1 - 3±%) through the
interior of the property. General topography slopes from west to east.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey website:
http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx,
the majority of the site consists of Nunn Clay Loam, which falls into Hydrologic Soil
Group C.
4. The proposed project site plan is composed of the development of a commercial and
student housing development with amenities. Associated site work, water, and sewer
lines will be constructed with the development. Onsite water quality treatment is
proposed and will consist of several features which are discussed in Section IV,
below.
PROJECT SITE
Saint John XXIII
Preliminary Drainage Report 3
Figure 2– Proposed Site Plan
5. There are no known irrigation laterals crossing the site.
6. The proposed land use is mixed-use.
Saint John XXIII
Preliminary Drainage Report 4
C. Floodplain
1. The project site is not encroached by any FEMA 100-year floodplain, please see
Appendix F for a copy of FIRM Map Number 08069C0978G (Revised 5/2/2012).
However, the City-designated W. Elizabeth Street flood fringe does encroach along the
northern border of the site. The CSU Underpass LOMR has been obtained from the
City of Fort Collins, we and have utilized the data for establishing base (100-year)
flood elevations through the site.
Figure 3 –Area Floodplain Mapping
2. A Critical Facilities are not allowed in the floodplain. However, a City of Fort Collins
CLOMR/LOMR process will be undertaken to reflect the fill to be placed on the site. It
is anticipated that the fill will effectively shift the 100-year flood fringe to the north,
putting the majority of the site outside of the flood fringe. A CLOMR/LOMR will show
this shift in the flood fringe, and will effectively re-map the City flood zone such that
the buildings will no longer be subject to Chapter 10 of City Code.
3. Three of the four proposed buildings are currently shown in the W.Elizabeth Flood
Fringe. The base (100-year) flood elevation in the vicinity of the west building is
5030.20 (NAVD 88). This flood elevation was interpolated at the upstream (west)
corner of the proposed west building.
4. The base (100-year) flood elevation in the vicinity of the middle building is 5029.00
(NAVD 88). This flood elevation was interpolated at the upstream (west) corner of
the proposed west building.
5. The base (100-year) flood elevation in the vicinity of the proposed east building is
5026.90 (NAVD 88). This flood elevation was interpolated at the upstream (west)
corner of the proposed west building.
PROJECT SITE
Saint John XXIII
Preliminary Drainage Report 5
6. The vertical datum utilized for site survey work is the City of Fort Collins Benchmark
#20-97 (Elevation=5050.15; NAVD 88).
7. It is noted that some of the surrounding developments have used the NGVD 29
(unadjusted) datum. The conversion from NAVD 88 to NGVD 29 (unadjusted) datum
is -3.18-ft.
8. Foundation for the east structure will be a combination of slab on grade and a
basement foundation.
9. The foundation for the middle and west structure will be slab on grade.
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site lies within the Old Town Master Drainage Basin. Per the Old Town
Master Drainage Plan, onsite detention is required. Onsite detention is required for the
runoff volume difference between the 100-year developed inflow rate and the 2-year
historic release rate.
B. Sub-Basin Description
1. The subject property historically drains overland from the west to the east. Runoff
from the majority of the site has historically been collected in the adjacent Shields
Street Right of Way.
2. A more detailed description of the project drainage patterns is provided below.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the proposed
project.
B. Four Step Process
The overall stormwater management strategy employed with the proposed project utilizes
the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters.
The following is a description of how the proposed development has incorporated each
step.
Step 1 – Employ Runoff Reduction Practices
Several techniques have been utilized with the proposed development to facilitate the
reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the
current use by implementing multiple Low Impact Development (LID) strategies including:
Paver System with StormTech Chambers
Sand Filter
Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with
Slow Release
Saint John XXIII
Preliminary Drainage Report 6
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 majority of stormwater runoff from the site will
ultimately be intercepted and treated using LID treatment methods prior to exiting the site.
Step 3 – Stabilize Drainageways
There are no major drainageways within the subject property. While this step may not
seem applicable to proposed development, the project indirectly helps achieve stabilized
drainageways nonetheless. By providing water quality treatment, where none previously
existed, sediment with erosion potential is 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.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
A portion of the site will be treated via a paver system.
StormTech chambers will receive the majority of onsite runoff; an isolator row will
provide LID treatment, providing filtration of suspended solids.
C. Development Criteria Reference and Constraints
The subject property is surrounded by currently developed properties. Thus, several
constraints have been identified during the course of this analysis that will impact the
proposed drainage system including:
Existing elevations along the property lines will generally be maintained.
As previously mentioned, overall drainage patterns of the existing site will be
maintained.
Elevations of existing downstream facilities that the subject property will release to
will be maintained.
Existing flows from the north and west will be safely conveyed through the
proposed site.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
associated with the proposed development. Tabulated data contained in Table RA-7
has been utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
3. Three separate design storms have been utilized to address distinct drainage
scenarios. A fourth design storm has also been computed for comparison purposes.
The first design storm considered is the 80th percentile rain event, which has been
employed to design the project’s water quality features. The second event analyzed is
the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The third
event considered is the “Major Storm,” which has a 100-year recurrence interval.
The fourth storm computed, for comparison purposes only, is the 10-year event.
4. No other assumptions or calculation methods have been used with this development
that are not referenced by current City of Fort Collins criteria.
Saint John XXIII
Preliminary Drainage Report 7
E. Hydraulic Criteria
1. As previously noted, the subject property maintains historic drainage patterns.
2. All drainage facilities proposed with the project are designed in accordance with
criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District
(UDFCD) Urban Storm Drainage Criteria Manual.
3. As discussed above, the subject property is located in a City designated 100-year
floodplain. However, a City CLOMR/LOMR will be undertaken to remove proposed
buildings from the flood fringe.
4. The proposed project does not propose to modify any natural drainageways.
F. Modifications of Criteria
1. The proposed development is not requesting any modifications to criteria at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the project drainage design are to maintain existing drainage
patterns, and to ensure no adverse impacts to any adjacent properties.
2. LID treatment will be provided using a combination of a paver system and StormTech
chambers.
3. Drainage patterns anticipated for drainage basins shown in the Drainage Exhibit are
described below.
Basin 1
Basin 1 is primarily composed of landscaped areas, and a small amount of paved
area. This basin will generally drain via sheet flow directly into adjacent City Park
Avenue and University Avenue. Runoff from this basin will not be detained; therefore,
the overall site release rate has been reduced to compensate for this undetained
release.
Basin 2
Basin 2 is primarily composed of landscaped areas, proposed buildings and amenities.
This basin will drain via sheet flow and roof drain system primarily to an access drive
running along the north side of the basin. Access drive curb and gutter will direct
runoff into the onsite chamber system. A paver field is also proposed within Basin 2,
which will provide LID treatment of a portion of the basin prior to discharge into the
main chamber system. Runoff from the entirety of Basin 2 basin will be detained and
treated in the onsite chamber system, and released into the existing storm line system
in Shields St.
Basin 3
Basin 3 is composed of landscaped areas and sidewalk. This basin will generally
drain via sheet flow directly into adjacent Shields Street and University Avenue.
Runoff from this basin will not be detained; therefore, the overall site release rate has
been reduced to compensate for this undetained release.
Saint John XXIII
Preliminary Drainage Report 8
Basins OS1, OS2, and OS3
Basins OS1, OS2, and OS3 are composed of offsite drainage areas to the north of the
site. These areas are fully developed with portions of the basins consisting of
commercial development and paved parking areas. An offsite basin exhibit has been
provided in the appendix, as well as peak 100-year discharge calculations. Peak
100-year discharge from these basins will safely conveyed along the site northern
boundary into the west curb and gutter of Shields Street.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this report.
B. Specific Details
1. One onsite detention facility will be provided within the site. A StormTech
chamber system will provide detention as well as LID treatment in the Isolator
Row for Basin 2. The paver system within Basin 2 will serve as LID treatment
for a portion of Basin 2 and will provide pre-treatment prior to discharge into
the chamber detention system.
2. Based on calculations provided in Appendix D, the required detention volume
for the proposed concrete vault is 0.42 Ac-Ft.
3. A total combined release rate has been determined for the proposed detention
facilities has been set at 6.39 cfs. This release rate has been determined
based on the methodology utilized for previous projects in close proximity to
the current project (approved Final Drainage Report for “The Retreat at 1200
Plum”, Ref. 6; approved Final Drainage Report for “Scott Plaza”, Ref. 7). The
methodology accounts for impervious area that is allowed to be
“grandfathered”. There are 3.12 acres of impervious area within the
development site which drains to Shields Street. A 100-year discharge from
this impervious area of 19.35 cfs has been calculated. There are 2.44 acres
of pervious area within the development site which also drains to Shields
Street. A 2-year discharge of 0.83 cfs has been calculated from this pervious
area. The sum of “grandfathered” impervious area discharge into Shields
Street combined with 2-year pervious area discharge is 20.19 cfs, which is
considered as the allowable peak release rate for the site. We have subtracted
the 100-year undetained discharge computed from Basin 3 (2.60 cfs total) for
an allowable release rate of 20.19-2.60=17.59 cfs.
4. LID features within the site include a StormTech chamber system for Basin 2,
and a paver system within Basin 2. Please refer to Appendix C for an LID
Exhibit and all pertinent calculations and information. As shown in Appendix
C, the proposed LID treatment design exceeds the 75% treatment
requirement.
5. Stormwater facility Standard Operating Procedures (SOP) will be provided by
the City of Fort Collins in the Development Agreement.
Saint John XXIII
Preliminary Drainage Report 9
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the proposed project complies with the City of Fort
Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with this project complies with requirements for the Old
Town Master Drainage Basin.
3. The drainage plan and stormwater management measures proposed with the
proposed development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit any potential
damage associated with its stormwater runoff by providing detention and water
quality mitigation features.
2. The drainage concept for the proposed development is consistent with requirements
for the Old Town Master Drainage Basin.
Saint John XXIII
Preliminary Drainage Report 10
References
1. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No.
174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code.
2. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
4. Downtown River District (DTRD) Final Design Report, Ayres Associates, February 2012.
5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado.
6. Final Drainage and Erosion Control Report for The Retreat at 1200 Plum, Northern
Engineering, April 22, 2009.
7. Final Drainage and Erosion Control Report for Scott Plaza, Northern Engineering, June
10, 2014.
APPENDIX A
Hydrologic Computations, Historic Drainage Exhibit
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: 1560-001
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: ATC
Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….. 0.50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.50 40%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Pavers
(ac)
Area of
Lawn, Rain
Garden, or
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
1 6603 0.15 0.08 0.02 0.05 0.00 0.00 0.93 0.93 1.00 92.8%
2 212533 4.88 2.68 0.59 1.46 0.00 0.15 0.93 0.93 1.00 92.8%
3 22933 0.53 0.29 0.06 0.16 0.00 0.02 0.93 0.93 1.00 92.8%
OS1 14248 0.33 0.22 0.00 0.10 0.00 0.00 0.95 0.95 1.00 96.9%
OS2 16613 0.38 0.35 0.00 0.03 0.00 0.00 0.95 0.95 1.00 99.1%
OS3 37652 0.86 0.83 0.00 0.03 0.00 0.00 0.95 0.95 1.00 99.6%
Historic Site
(Pervious Area) 106099 2.44 0.00 0.00 0.00 0.00 2.44 0.25 0.25 0.31 0.0%
Historic Site
(Impervious Area) 135970 3.12 2.38 0.16 0.58 0.00 0.00 0.95 0.95 1.00 97.6%
Overland Flow, Time of Concentration:
Project: 1560-001
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = Ti + Tt (Equation RO-2)
Velocity (Gutter Flow), V = 20·S½
Velocity (Swale Flow), V = 15·S½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf=1.00)
C*Cf
(10-yr
Cf=1.00)
C*Cf
(100-yr
Cf=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Tc Check
2-yr
Rational Method Equation: Project: 1560-001
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 0.15 6 6 5 0.93 0.93 1.00 2.76 4.72 9.95 0.39 0.66 1.51 0.19
2 2 4.88 16 16 15 0.93 0.93 1.00 1.84 3.14 6.52 8.34 14.21 31.81 4.17
3 3 0.53 11 11 11 0.93 0.93 1.00 2.13 3.63 7.57 1.04 1.78 3.99 0.52
OS1 OS1 0.33 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.89 1.51 3.25 0.44
OS2 OS2 0.38 6 6 5 0.95 0.95 1.00 2.76 4.72 9.95 1.00 1.71 3.79 0.50
OS3 OS3 0.86 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 2.34 4.00 8.60 1.17
Historic Site
(Pervious
Area)
Historic Site
(Pervious Area) 2.44 27 27 25 0.25 0.25 0.31 1.37 2.34 4.98 0.83 1.42 3.79 0.42
Historic Site
(Impervious
Area)
Historic Site
(Impervious Area) 3.12 18 18 17 0.95 0.95 1.00 1.73 2.95 6.20 5.12 8.73 19.35 2.56
WQ Flow
(cfs)
RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
ATC
February 6, 2019
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
OS1 OS2
H1
OS1 OS2
H1
OS3
OS3
SHIELDS ST.
W. ELIZABETH ST.
HISTORIC DRAINAGE EXHIBIT
E NGINEER ING 1560-001
N O R T H E RN
02.06.19
D:\PROJECTS\1560-001\DWG\DRNG\1560-001_HISTDRNG.DWG
( IN FEET )
1 inch = ft.
80 0 80 Feet
80
NORTH
APPENDIX B
USDA Soils Information
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Larimer County
Natural Area, Colorado
Resources
Conservation
Service
February 1, 2019
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface.................................................................................................................... 2
How Soil Surveys Are Made..................................................................................5
Soil Map.................................................................................................................. 8
Soil Map................................................................................................................9
Legend................................................................................................................10
Map Unit Legend................................................................................................ 11
Map Unit Descriptions.........................................................................................11
Larimer County Area, Colorado...................................................................... 13
3—Altvan-Satanta loams, 0 to 3 percent slopes......................................... 13
76—Nunn clay loam, wet, 1 to 3 percent slopes......................................... 15
References............................................................................................................17
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
Custom Soil Resource Report
6
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
8
9
Custom Soil Resource Report
Soil Map
4491320 4491360 4491400 4491440 4491480 4491520 4491560
4491320 4491360 4491400 4491440 4491480 4491520 4491560
491520 491560 491600 491640 491680 491720 491760 491800 491840 491880
491520 491560 491600 491640 491680 491720 491760 491800 491840 491880
40° 34' 29'' N
105° 6' 1'' W
40° 34' 29'' N
105° 5' 44'' W
40° 34' 21'' N
105° 6' 1'' W
40° 34' 21'' N
105° 5' 44'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:1,830 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
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
3 Altvan-Satanta loams, 0 to 3
percent slopes
1.2 20.7%
76 Nunn clay loam, wet, 1 to 3
percent slopes
4.5 79.3%
Totals for Area of Interest 5.7 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
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
13
Hydrologic Soil Group: B
Hydric soil rating: No
Description of Satanta
Setting
Landform: Terraces, structural benches
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
76—Nunn clay loam, wet, 1 to 3 percent slopes
Map Unit Setting
National map unit symbol: jpxq
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
Nunn, wet, and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Nunn, Wet
Setting
Landform: Alluvial fans, stream terraces
Landform position (three-dimensional): Base slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Alluvium
Typical profile
H1 - 0 to 10 inches: clay loam
H2 - 10 to 47 inches: clay loam, clay
H2 - 10 to 47 inches: clay loam, loam, gravelly sandy loam
H3 - 47 to 60 inches:
H3 - 47 to 60 inches:
H3 - 47 to 60 inches:
Properties and qualities
Slope: 1 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Somewhat poorly drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to
moderately high (0.06 to 0.60 in/hr)
Depth to water table: About 24 to 36 inches
Frequency of flooding: Rare
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0
mmhos/cm)
Available water storage in profile: Very high (about 19.8 inches)
Interpretive groups
Land capability classification (irrigated): 2w
Custom Soil Resource Report
15
Land capability classification (nonirrigated): 3s
Hydrologic Soil Group: C
Hydric soil rating: No
Minor Components
Heldt
Percent of map unit: 6 percent
Hydric soil rating: No
Dacono
Percent of map unit: 3 percent
Hydric soil rating: No
Mollic halaquepts
Percent of map unit: 1 percent
Landform: Swales
Hydric soil rating: Yes
Custom Soil Resource Report
16
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
17
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
18
APPENDIX C
Water Quality Calculations, LID Information
VAULT
F.O.
CC CC
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
VAULT
F.O.
AC
AC
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
UNIVERSITY AVENUE
SOUTH SHIELDS STREET
CITY PARK AVENUE
VAULT
F.O.
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
VAULT
F.O.
DN UP
UP
X X
X
X
X
X
X X
X
DN UP
DN UP
DN UP
DN
TF
TF
TF
TF
UNIVERSITY AVENUE
SOUTH SHIELDS STREET
CITY PARK AVENUE
ROOFTOP
CONCRETE
ASPHALT
GRAVEL
SURFACE
B M
VAULT
F.O.
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
VAULT
F.O.
T T
T
T
CONTROL
IRR
M
T T
X
ST
SS
SS
DN
UP
UP
DN UP
DN UP
DN UP
DN
TF
TF
TF
TF
UD
UD
UD UD
UD UD UD
UD
UD UD
UNIVERSITY AVENUE
SOUTH SHIELDS STREET
CITY PARK AVENUE
RAIN GARDEN
REQUIRED VOLUME: 18,209 CU. FT.
PROVIDED VOLUME: 18,398 CU. FT.
TREATMENT AREA: 186,441 SF
SAINT JOHN XXIII AND LOMBARDY
STUDENT HOUSING
SHEET NO:
D:\PROJECTS\1560-001\DWG\DRNG\1560-001_LID.DWG
301 N. Howes Street, Suite 100
Fort Collins, Colorado 80521
E NGINEER ING
N O R T H E RN
PHONE: 970.221.4158
www.northernengineering.com
DRAWING REFERENCE:
LID TREATMENT EXHIBIT B. Ruch
1 in = 100 ft
February 6, 2019 LID-1
APPENDIX D
Detention Calculations
ATC
Pond No : Chamber System
1
100-yr
1.00
Area (A)= 5.30 acres 18216 ft3
Max Release Rate = 14.50 cfs 0.418 ac-ft
Time Time
100-yr
Intensity
Q100
Inflow
(Runoff)
Volume
Outflow
(Release)
Volume
Storage
Detention
Volume
(mins) (secs) (in/hr) (cfs) (ft3) (ft3) (ft3)
5 300 9.950 52.74 15821 4350.0 11470.5
10 600 7.720 40.92 24550 8700.0 15849.6
15 900 6.520 34.56 31100 13050.0 18050.4
20 1200 5.600 29.68 35616 17400.0 18216.0
25 1500 4.980 26.39 39591 21750.0 17841.0
30 1800 4.520 23.96 43121 26100.0 17020.8
35 2100 4.080 21.62 45410 30450.0 14960.4
40 2400 3.740 19.82 47573 34800.0 12772.8
45 2700 3.460 18.34 49513 39150.0 10362.6
50 3000 3.230 17.12 51357 43500.0 7857.0
55 3300 3.030 16.06 52995 47850.0 5144.7
60 3600 2.860 15.16 54569 52200.0 2368.8
65 3900 2.720 14.42 56222 56550.0 -327.6
70 4200 2.590 13.73 57653 60900.0 -3246.6
75 4500 2.480 13.14 59148 65250.0 -6102.0
80 4800 2.380 12.61 60547 69600.0 -9052.8
85 5100 2.290 12.14 61899 73950.0 -12051.3
90 5400 2.210 11.71 63250 78300.0 -15049.8
95 5700 2.130 11.29 64347 82650.0 -18302.7
100 6000 2.060 10.92 65508 87000.0 -21492.0
105 6300 2.000 10.60 66780 91350.0 -24570.0
110 6600 1.940 10.28 67861 95700.0 -27838.8
115 6900 1.890 10.02 69117 100050.0 -30932.7
120 7200 1.840 9.75 70214 104400.0 -34185.6
DETENTION POND CALCULATION; FAA METHOD
Project Number : 1560-001
Date : 2/6/19
1.35
Design Point
Design Storm Required Detention Volume
Developed "C" =
Project Location : Fort Collins
Input Variables Results
Calculations By:
APPENDIX E
Erosion Control Report
Saint John XXIII
Preliminary Erosion Control Report
PRELIMINARY 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 existing and proposed storm inlets. Vehicle tracking control pads, spill
containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site
restrooms shall also be provided by the Contractor.
Grading and Erosion Control Notes can be found on the Utility Plans. The Final Plan set will
contain a full-size Erosion Control sheet 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 the Development Agreement for the
development. 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, prior to any earth disturbance
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 F
Current Effective FIRM Panel
MAP POCKET
UD
UD
UD
UD
UD UD UD
UD
UD UD UD UD UD UD
UD
UD UD
UD
B M
VAULT
F.O.
VAULT
ELEC
TELE
VAULT
ELEC
VAULT
ELEC
C
VAULT
ELEC
VAULT
ELEC
ELEC
C
VAULT
ELEC
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
VAULT
ELEC
VAULT
ELEC
VAULT
ELEC VAULT
VAULT ELEC
ELEC
VAULT
TELE
VAULT
ELEC
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
VAULT
F.O.
T T
UD
UD
UD
UD
FDC
FDC
FDC
FDC
UD
UD
UD UD UD UD UD UD
UD
UD UD UD
UD
UD
V
AULT
F.O.
VAULT
ELEC
TELE
VAULT
ELEC
VAULT
ELEC
C
VAULT
ELEC
VAULT
ELEC
ELEC
C
VAULT
ELEC
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
VAULT
ELEC
VAULT
ELEC
VAULT
ELEC VAULT
VAULT ELEC
ELEC
VAULT
TELE
VAULT
ELEC
CONTROL
IRR
CONTROL
IRR
CONTROL
IRR
VAULT
F.O.
T T
T
ELEC
VAULT
ELEC
T
ELEC ELEC
CONTROL
IRR
M
CONTROL
IRR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
T
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC T
ELEC
T
T
T
X
T
T
T
T T
T
X
X
T
T
T
T T T
T T
T
T
ST
ST
ST
ST
ST
ST ST
ST
D
N UP
UP
X
X
X X X
X X
X
X
X
X X X
X
X
X
X
DN UP
DN UP
DN UP
DN
X
TF
TF
TF
TF
X
UNIVERSITY AVENUE
UNIVERSITY AVENUE
SOUTH SHIELDS STREET
CITY PARK AVENUE
WEST ELIZABETH STREET
WEST ELIZABETH STREET
NICOL CAMPUS WEST
1205 W. ELIZABETH ST. A
NICOL CAMPUS
WEST LIMITED
1213 W.
ELIZABETH ST.
GLEASON/WESTSIDE
INVESTMENTS
LLC
1301 W.
ELIZABETH ST.
JDH2 INVESTMENTS LLC
1305 W. ELIZABETH ST.
PHILLIPS DAVID J LIVING
TRUST (.615)
1335 W. ELIZABETH ST. 160
1221 W.
ELIZABETH ST.
5035
5034
5033
5032
5031
5031
5027 5027
5028 5028
5029 5029
5030
5030
658
688
709
740
796
814
875
935
995
1036
1056
1169
1225
1316
1705
777
1409
1847
1946
2073
1536
5026.7
5026.8
5026.8
5026.9
5026.8
5026.8
5026.8
5026.9
5026.9
5027.6
5028.1
5028.6
5029.1
5029.8
5030.8
5031.8
5032.8
5034.5
5026.7
5026.5
5026.2
BLDG A
BLDG B
BLDG C
CHURCH
BLDG
FFE=40.00
FFE=34.00 FFE=34.00
FFE=30.50
FFE=32.00
FFE=30.50
FFE=32.00
FFE=30.50
FFE=37.00
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
NORTH
( IN FEET )
1 inch = ft.
60 0 60 Feet
60
120 180
SAINT JOHN XXIII AND
LOMBARDY STUDENT HOUSING
Sheet
These drawings are
instruments of service
provided by Northern
Engineering Services, Inc.
and are not to be used for
any type of construction
unless signed and sealed by
a Professional Engineer in
the employ of Northern
Engineering Services, Inc.
NOT FOR CONSTRUCTION
REVIEW SET
E NGINEER ING
N O R T H E RN
FORT COLLINS: 301 North Howes Street, Suite 100, 80521
GREELEY: 820 8th Street, 80631
970.221.4158
northernengineering.com
of 18
C900
FLOODPLAIN EXHIBIT
18
NORTH
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
NORTH
LEGEND:
PROPOSED CONTOUR
EXISTING STORM SEWER
PROPOSED STORM SEWER
PROPOSED SWALE
EXISTING CONTOUR
PROPOSED CURB & GUTTER
PROPOSED STORM INLET
PROPOSED CONCRETE
CROSS PAN (TYP.)
PEDESTRIAN ACCESS RAMPS
PROPERTY BOUNDARY
CROSS-SECTION (CSU CLOMR)
NOTES:
1. REFER TO THE PLAT FOR LOT AREAS, TRACT SIZES, EASEMENTS, LOT DIMENSIONS, UTILITY
EASEMENTS, OTHER EASEMENTS, AND OTHER SURVEY INFORMATION
2. THIS PROJECT IS LOCATED WITHIN A CITY-REGULATED 100-YEAR FLOODWAY AND FLOOD FRINGE
AND MUST COMPLY WITH CHAPTER 10 OF THE CITY CODE.
3. ALL ELEVATIONS DEPICTED IN PLAN VIEW AND BENCHMARKS LISTED HEREON ARE PER THE CITY OF
FORT COLLINS VERTICAL CONTROL DATUM (NAVD 88).
4. ANY ITEMS LOCATED IN THE FLOODWAY THAT CAN FLOAT (E.G., PICNIC TABLES, BIKE RACKS, ETC.)
MUST BE ANCHORED.
5. A FLOODPLAIN USE PERMIT SHALL BE REQUIRED FOR EACH SITE CONSTRUCTION ELEMENT IN THE
FLOODPLAIN, INCLUDING BUILDING. THE FLOODPLAIN USE PERMIT FOR THE BUILDING WILL BE
APPROVED AT THE TIME OF BUILDING PERMIT APPLICATION.
6. A FLOODPLAIN USE PERMIT AND NO RISE CERTIFICATION IS REQUIRED PRIOR TO PERFORMING ANY
WORK WITHIN THE FLOODWAY (I.E., CURB CUT REMOVAL, LANDSCAPING).
7. NO STORAGE OF MATERIALS OR EQUIPMENT SHALL BE ALLOWED IN THE FLOODWAY, WHETHER
TEMPORARY (DURING CONSTRUCTION) OR PERMANENT. LANDSCAPING SHALL ALSO MEET THE
REQUIREMENTS FOR NO RISE IN THE FLOODWAY.
8. REFER TO THE PRELIMINARY DRAINAGE REPORT FOR SAINT JOHN XXIII AND LOMBARDY STUDENT
HOUSING, DATED FEBRUARY 6, 2019 FOR ADDITIONAL INFORMATION.
9. A POST-CONSTRUCTION ELEVATION CERTIFICATE MUST BE APPROVED BEFORE A CERTIFICATE OF
OCCUPANCY WILL BE ISSUED.
10. ALL HVAC EQUIPMENT IS TO BE PLACED AT OR ABOVE THE REGULATORY FLOOD PROTECTION
ELEVATION.
11. HORIZONTAL CONTROL: CITY OF FORT COLLINS GROUND MASTER CONTROL.
FIELD SURVEY BY:
BENCHMARKS:
NTS
BASE FLOOD ELEVATION (CSU CLOMR)
ELEVATION NGVD 88 5000
100-YR FLOODPLAIN
(PER CSU CLOMR)
100-YR FLOODWAY
(PER CSU CLOMR)
FLATIRONS, INC.
PROJECT NO. 18-71,080
DATE: APRIL 2018
ADDITIONAL SURVEY:
NORTHERN ENGINEERING SERVICES
PROJECT NO. 1560-001
DATE: OCTOBER 2018
1036
PROJECT DATUM: NAVD88
CITY OF FORT COLLINS BENCHMARK 20-97
AT THE SOUTHWEST CORNER OF WEST ELIZABETH AND CONSTITUTION AVE. ON A
CONCRETE TRAFFIC SIGNAL BASE.
ELEV.= 5050.15
CITY OF FORT COLLINS BENCHMARK 19-97
AT THE SOUTHEAST CORNER OF WEST ELIZABETH AND SHIELDS ST., ON A CONCRETE
TRAFFIC SIGNAL BASE.
ELEV.= 5025.74
PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM. SURROUNDING
DEVELOPMENTS HAVE USED NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS
DATUM) FOR THEIR VERTICAL DATUMS.
IF NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) IS REQUIRED FOR
ANY PURPOSE, THE FOLLOWING EQUATION SHOULD BE USED:
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = NAVD88 - 3.18'
BASIS OF BEARINGS
THE BASIS OF BEARINGS IS THE EAST LINE OF THE SOUTHEAST QUARTER OF SECTION
15-7-69 AS BEARING SOUTH 00° 29' 45" WEST (ASSUMED BEARING).
T
ELEC
VAULT
ELEC
T
ELEC ELEC
CONTROL
IRR
M
CONTROL
IRR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
T
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC
BRKR
ELEC T
ELEC
X X X
ST
ST
ST
ST ST
ST
D
N UP
UP
X X X
X
X
X X
X
X
X X X
X
X
X X
X
DN UP
DN UP
DN
UP
DN
X
TF
TF
TF
TF
X
UNIVERSITY AVENUE
UNIVERSITY AVENUE
SOUTH SHIELDS STREET
CITY PARK AVENUE
WEST ELIZABETH STREET
WEST ELIZABETH STREET
NICOL CAMPUS WEST
1205 W. ELIZABETH ST. A
NICOL CAMPUS
WEST LIMITED
1213 W.
ELIZABETH ST.
GLEASON/WESTSIDE
INVESTMENTS
LLC
1301 W.
ELIZABETH ST.
JDH2 INVESTMENTS LLC
1305 W. ELIZABETH ST.
PHILLIPS DAVID J LIVING
TRUST (.615)
1335 W. ELIZABETH ST. 160
1221 W.
ELIZABETH ST.
100-YR FLOODWAY
(PER CSU CLOMR)
100-YR FLOODPLAIN
(PER CSU CLOMR)
CONNECT TO
EXISTING
STORM INLET
100-YR FLOODWAY
(PER CSU CLOMR)
100-YR FLOODPLAIN
(PER CSU CLOMR)
EXISTING
STORM DRAIN
PROPOSED
STORMTECH CHAMBERS
PROPOSED
STORM DRAIN
PROPOSED
STORM DRAIN
EXISTING
STORM DRAIN
(PRIVATE)
PROPOSED
INLET
PROPOSED
INLET
PROPOSED
INLET
PROPOSED
INLET
PROPOSED
INLET
EXISTING
INLET
PROPOSED AREA
DRAIN BASIN PROPOSED AREA
DRAIN BASIN
PROPOSED
UNDERDRAIN
PROPOSED
UNDERDRAINS
PROPOSED AREA
DRAIN BASIN
2
3
OS1
OS2
OS1
OS3
OS3
1
3
OS2
2
1
BLDG A
BLDG B
BLDG C
CHURCH
BLDG
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
NORTH
( IN FEET )
1 inch = ft.
60 0 60 Feet
60
120 180
LEGEND:
PROPOSED CONTOUR
PROPOSED STORM SEWER
PROPOSED SWALE
EXISTING CONTOUR
PROPOSED CURB & GUTTER
PROPERTY BOUNDARY
PROPOSED INLET
DESIGN POINT A
FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
PROPOSED SWALE SECTION
1 1
NOTES:
1. REFER TO THE PRELIMINARY DRAINAGE REPORT FOR SAINT JOHN XXIII AND LOMBARDY STUDENT
HOUSING, DATED FEBRUARY 6, 2019 FOR ADDITIONAL INFORMATION.
BENCHMARK
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
C
SAINT JOHN XXIII AND
LOMBARDY STUDENT HOUSING
Sheet
These drawings are
instruments of service
provided by Northern
Engineering Services, Inc.
and are not to be used for
any type of construction
unless signed and sealed by
a Professional Engineer in
the employ of Northern
Engineering Services, Inc.
NOT FOR CONSTRUCTION
REVIEW SET
E NGINEER ING
N O R T H E RN
FORT COLLINS: 301 North Howes Street, Suite 100, 80521
GREELEY: 820 8th Street, 80631
970.221.4158
northernengineering.com
of 18
C800
DRAINAGE EXHIBIT
17
NORTH
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
NORTH
DRAINAGE SUMMARY TABLE
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
1 1 0.15 0.93 1.00 5.6 5.1 0.4 1.5
2 2 4.88 0.93 1.00 15.9 15.4 8.3 31.8
3 3 0.53 0.93 1.00 11.1 10.5 1.0 4.0
OS1 OS1 0.33 0.95 1.00 5.1 5.0 0.9 3.3
OS2 OS2 0.38 0.95 1.00 5.5 5.0 1.0 3.8
OS3 OS3 0.86 0.95 1.00 5.4 5.0 2.3 8.6
PROJECT DATUM: NAVD88
CITY OF FORT COLLINS BENCHMARK 20-97
AT THE SOUTHWEST CORNER OF WEST ELIZABETH AND CONSTITUTION AVE. ON A CONCRETE TRAFFIC
SIGNAL BASE.
ELEV.= 5050.15
CITY OF FORT COLLINS BENCHMARK 19-97
AT THE SOUTHEAST CORNER OF WEST ELIZABETH AND SHIELDS ST., ON A CONCRETE TRAFFIC SIGNAL
BASE.
ELEV.= 5025.74
PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM. SURROUNDING DEVELOPMENTS
HAVE USED NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) FOR THEIR VERTICAL
DATUMS.
IF NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) IS REQUIRED FOR ANY PURPOSE,
THE FOLLOWING EQUATION SHOULD BE USED:
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = NAVD88 - 3.18'
BASIS OF BEARINGS
THE BASIS OF BEARINGS IS THE EAST LINE OF THE SOUTHEAST QUARTER OF SECTION 15-7-69 AS BEARING
SOUTH 00° 29' 45" WEST (ASSUMED BEARING).
DRAWN BY:
SCALE:
ISSUED:
( IN FEET )
0
1 INCH = 100 FEET
100 100
LEGEND
PERMEABLE PAVER AREA
STORMTECH CHAMBER AREA
STORMTECH ISOLATOR ROW
TREATMENT AREA
SAINT JOHN XXIII AND LOMBARDY STUDENT HOUSING ON-SITE LID TREATMENT
Project Summary
Total Impervious Area 197,049 sf
Target Treatment Percentage 75%
Minimum Area to be Treated by LID measures 147,786.75 sf
StormTech Chambers
Total StormTech Treatment Area 186,441 sf
Total Treatment Area 186,441 sf
Percent Total Project Area Treated 94.6% UNTREATED AREA
AREA (SF) % IMPERV.
IMPERV.
AREA (SF)
22,213
15,301
88,088
2,301
100%
100%
100%
40% 920
TOTALS 127,903 TOTAL= 126,522
ROOFTOP
CONCRETE
ASPHALT
PAVERS
SURFACE
AREA (SF) % IMPERV.
IMPERV.
AREA (SF)
114,836
43,882
25,295
13,036
100%
100%
100%
40%
TOTALS 197,049 TOTAL= 189,227
EXISTING
PROPOSED
114,836
5,214
22,213
15,301
88,088
43,882
25,295
D:\PROJECTS\1560-001\DWG\DRNG\1560-001_IMPERV.DWG
SAINT JOHN XXIII AND LOMBARDY STUDENT HOUSING
FORT COLLINS
COLORADO
301 N. Howes Street, Suite 100
Fort Collins, Colorado 80521
E NGINEER ING
N O R T H E RN
PHONE: 970.221.4158
www.northernengineering.com
EXISTING VS. PROPOSED
IMPERVIOUS AREA
DRAWN BY
B. Ruch
DATE
February 6, 2019
PROJECT
1560-001 SK-C1
SCALE DRAWING
1"=100'
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Sep 20, 2015—Oct
21, 2017
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
Tc
(min)
Q = C f ( C )( i )( A )
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
1 1 No 0.95 0.95 1.00 45 2.00% 1.5 1.5 1.0 350 0.50% 1.41 4.1 0 0.00% N/A N/A 12.2 6 6 5
2 2 No 0.95 0.95 1.00 45 2.00% 1.5 1.5 1.0 1100 0.50% 1.41 13.0 185 2.00% 2.12 1.5 16.4 16 16 15
3 3 No 0.95 0.95 1.00 55 2.00% 1.7 1.7 1.1 800 0.50% 1.41 9.4 0 0.00% N/A N/A 14.8 11 11 11
OS1 OS1 No 0.90 0.90 1.00 76 1.20% 3.1 3.1 1.5 154 0.40% 1.26 2.0 0 0.00% N/A N/A 11.3 5 5 5
OS2 OS2 No 0.90 0.90 1.00 85 0.90% 3.6 3.6 1.8 147 0.40% 1.26 1.9 0 0.00% N/A N/A 11.3 6 6 5
OS3 OS3 No 0.90 0.90 1.00 45 1.80% 2.1 2.1 1.0 308 0.60% 1.55 3.3 0 0.00% N/A N/A 12.0 5 5 5
Historic Site
(Pervious
Area)
Historic Site
(Pervious
Area) No 0.25 0.25 0.31 480 2.10% 27.2 27.2 25.2 0 0.00% N/A N/A 0 0.00% N/A N/A N/A 27 27 25
Historic Site
(Impervious
Area)
Historic Site
(Impervious
Area) No 0.25 0.25 0.31 164 2.90% 14.3 14.3 13.2 377 0.80% 1.79 3.5 0 0.00% N/A N/A N/A 18 18 17
TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point
Basin
Overland Flow
ATC
February 6, 2019
Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients have been estimated for preliminary purposes and are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious
taken from UDFCD
USDCM, Volume I.
10-year Cf = 1.00
February 6, 2019