HomeMy WebLinkAboutALLIED BUILDING PRODUCTS - PDP - PDP180015 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTFINAL DRAINAGE REPORT
ALLIED BUILDING PRODUCTS
LOCATED AT 2155 MIDPOINT
DRIVE
CITY OF FORT COLLINS,
STATE OF COLORADO
Prepared By:
Baseline Engineering Corporation
4007 S. Lincoln Ave, Suite 405
Loveland, CO 80537
Todd Rand, PE
_____________________________
October 5, 2018
Rev. November 19, 2018
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Dohn Construction hereby certifies that the drainage facilities for ALLIED
BUILDING PRODUCTS shall be constructed according to the design
presented in this report. I understand that the City of Fort Collins does not
and will not assume liability for drainage facilities designed and/or
certified by my Engineer. I also understand that the City of Fort Collins
relies on the representations of others to establish that drainage facilities
are designed and constructed in compliance with City guidelines,
standards, or specifications. Review by the City of Fort Collins can
therefore in no way limit or diminish any liability, which I or any other
party may have with respect to the design or construction of such facilities.
Name of Responsible Party
___________________________________________
Authorized Signature Date
Attest: _____________________________________
Notary Public Authorized Signature Date
I hereby certify that this report for the drainage design of Allied Building Products was
prepared by me (or under my direct supervision) in accordance with the previsions of the City
of Fort Collins storm drainage criteria for the owners thereof.”
________________________________________
Todd G Rand, P.E.
State of Colorado No. 37686
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Table of Contents
I. GENERAL LOCATION AND DESCRIPTION ......................................................................... 4
A. Location ............................................................................................................................... 4
B. Description of Property ...................................................................................................... 4
C. Floodplain Submittal Requirements ................................................................................. 5
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. Directly Connected Impervious Area (DCIA) and Four Step Process Compliance ..... 6
C. Development Criteria Reference and Constraints ........................................................... 7
D. Hydrological Criteria .......................................................................................................... 7
E. Hydraulic Criteria............................................................................................................... 8
F. Floodplain Regulations Compliance .................................................................................. 8
G. Modifications of Criteria .................................................................................................... 9
IV. DRAINAGE FACILITY DESIGN ............................................................................................... 9
A. General Concept ................................................................................................................. 9
B. Specific Details................................................................................................................... 10
V. CONCLUSIONS .......................................................................................................................... 11
A. Compliance with standards .............................................................................................. 11
B. Drainage Concept .............................................................................................................. 11
VI. REFERENCES ............................................................................................................................. 12
VI. APPENDIX ......................................................................................................................................... 13
A. NRCS Soils Map ................................................................................................................................... 14
B. FEMA Firm Map ................................................................................................................................. 15
C. Composite C-Factor Calculations, ...................................................................................................... 16
D. WQCV Calculations, ........................................................................................................................... 17
E. Reference Sheets ................................................................................................................................... 18
F. Proposed Drainage Plan ....................................................................................................................... 19
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I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. A vicinity map has been provided in Appendix A.
2. The project is located in Lot 2 of Centerpoint Plaza in the Northwest ¼ of
Section 20, Township 7 North, Range 68 West of the 6th Prime Meridian,
City of Fort Collins, County of Larimer, State of Colorado.
3. The project site is located on the south side of Midpoint Drive, east of
South Timberline Road.
4. There are no major drainage ways or facilities within the site. There are
drainage easements on the east and west sides of Lot 2, Lot 3 to the south,
is developed. There is a detention pond in the southern half Lot 1, to the
west.
5. To the north, the property is bounded by Midpoint Drive, to the east by
Larimer County Community Corrections, to the south by Lot 3 and Great
Western Railway and to the west, Lot 1 containing Riverbend Trail Office
Condos Ph1, of Centerpoint Plaza Replat 1.
B. Description of Property
1. The total area of Lot 2 is 1.853 acers. The project will disturb
approximately 1.75 acres of Lot 2 area. The remaining 0.103 acres are
covered by existing access, utility and drainage easements, minimal
disturbance will occur in the existing access and SW corner of Lot 2. Lot 3
has the same owner and that lot is developed with an existing building,
parking and open storage areas. This project will only affect Lot 2.
2. The eastern 36 feet, southern 70 feet and western 97 feet of Lot 2 are
access, utility and drainage easements, City of Fort Collins water and
sanitary mains have been installed in the western easement; a paved access
to Lots 1 and 3 is also located in the western easement. The remainder of
the Lot 2 is undeveloped and is covered primarily with native grass and
gravel parking. The majority of the site has a slight 1 to 3 percent slope to
the east; the eastern edge has a slope of 0.5 percent to the south. An NRCS
Soil Report classifies the soil as poorly drained. A copy of the report is
provided in Appendix D.
3. No major drainage ways directly impact the site. Spring Creek lies to the
north and the Cache La Poudre River lies to the east.
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4. The project will include the construction of a lean-to materials storage
building, drive aisles and landscaping. Site water quality control is
provided on the southern half of Lot 1 in an existing water quality pond.
5. There are no irrigation facilities on or near the project site.
6. Proposed land use is for a building materials, storage shed. The site is
zoned Employment District (E) which allows this use.
C. Floodplain Submittal Requirements
1. The site is not in a floodplain.
2. The FEMA FIRM panel number 08069C0983H, revised May 2, 2012, was
referenced and a copy is included in Appendix E.
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. This project is in the Spring Creek Drainage Basin.
2. The area of the Spring Creek Drainage Basin this project is located in is
mostly developed. The project site is a single lot infill development.
3. No irrigation facilities are known to influence or be influenced by the local
drainage design of this project.
B. Sub-Basin Description
1. Historic drainage patterns for the property are typically from west to east.
The subdivision currently has internal streets and utility infrastructure
installed.
2. Lot 2 is protected from offsite flows, on the north side by the existing curb
and gutters of Midpoint Drive and on the west side by existing curb and
gutters of the private access drive. This site slopes away from the existing
street and driveway and has no impacts from offsite flow.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
1. Following are deviations from the criteria: The eastern, and portions of the
southern boundary are too low to drain to the WQ pond without significant
amounts of fill and possibly retaining walls. These areas are not paved and
runoff will follow historic patterns. A portion of the existing paved access,
to Lot 3, in the southwest corner of this site is below a grade break and
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does not runoff to the existing WQ pond. Flow from this area of Lot 2 will
continue to flow to the south along the west lot line of Lot 3 following
historic patterns.
2. The site was designed to accommodate the allowable uses, and emergency
vehicle access with the proposed layout. Runoff from impervious surfaces
is conveyed by curb and gutter or overland on landscape surfaces to the
existing Water Quality Pond in Lot 1. The pond outlet structure was
designed for Water Quality Capture Volume (WQCV) and a 100-year
storm, developed flow release rate. The outlet structure is designed to
slowly release flows from frequent storm events and release flows up to a
100-year storm event at the developed condition runoff rate directly to
Spring Creek.
3. The project site currently drains to the east boundary. The site’s eastern
side will be built up to convey runoff from the new impervious surfaces to
the existing water quality pond in Lot 1, runoff from the grassed area along
the east boundary will flow south as it has historically.
B. Directly Connected Impervious Area (DCIA) and Four Step Process
Compliance
1. Employ Runoff Reduction Practices: This site uses a Grass Swale to treat
sediment and convey site runoff from the drive isle and loading areas to the
water quality pond. The building roof runoff will flow onto a terraced
Grass Buffer with underdrains, and combine with flows in the Grass Swale
at the west side of the improvements area.
2. Implement BMPs that provide a WQCV with slow release: This site uses
an existing water quality pond to treat frequent storm runoff events. The
release rate of the WQCV is 40 hours and has adequate volume for the
additional impervious area of this project.
3. Stabilize Drainage ways: This site will release developed flows into an
existing storm sewer, and water quality system on Lot 1 per previously
approved drainage reports. The developed flows are released into Spring
Creek north of the site per the previously approved drainage reports.
4. Implement Site Specific and Other Source Control BMP’s: A separate
Erosion and Sediment Control Plan has been developed with source control
BMP’s used from ground breaking operations to permanent stabilization
installations.
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C. Development Criteria Reference and Constraints
1. Two drainage studies were available at the time this report was written. Lot
2 was previously included in the Final Drainage Report for Centerpoint
Plaza, Phase 1, dated November 11, 2005 by DMW Civil Engineers and
the Final Drainage Report for Centerpoint Plaza First Replat, dated October
28, 2008 by DMW Civil Engineers. Lot 1 in these reports has an on-site
water quality pond. Developed flow from Lot 2 will be conveyed to the
water quality pond and released directly into the existing storm sewer at the
allowed developed rate.
2. The Centerpoint Plaza is bounded on the north by Midpoint Drive, the east
by the Larimer County Corrections Center, the south by existing railroad
tracks and on the west by Timberline Road. There are no effects from
adjacent drainage studies.
3. This Project Site is an infill development in an existing subdivision.
Development of this site will not cause any drainage impact to the existing
infrastructure.
D. Hydrological Criteria
1. Rainfall data was obtained from the City of Fort Collins Storm Drainage
Design Criteria Manual, Table RA-8. Rainfall data used for this design is
as follows:
Storm Return
Period
Intensity
(in/hr)
2 year 0.82 in.
10 year 1.40 in.
100 year 2.86 in.
2. The Rational Method was used to calculate runoff. Per the Fort Collins
Storm water Criteria, the runoff coefficients were adjusted for infrequent
storms. Therefore, C100 was applied a frequency factor of Cf=1.25.
Storm Return Period Frequency Factor, Cf
2, 5, 10 1.00
25 1.10
50 1.20
100 1.25
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3. Detention pond sizing, outlet structure configuration, and discharge rates
were calculated by DMW Civil Engineers. The pond outlet structure was
designed for WQCV plus direct discharge of the 100-year developed flows,
as previously discussed with the City of Fort Collins in the DMW Civil
Engineer reports. The stage storage volume of the pond was calculated
using the UDFCD empirical equations. Calculations in this study are based
on the water quality drainage area of 1.084 acres per discussions with City
of Fort Collins staff.
4. For the purposes of this design, the 2-year storm will be considered the
Minor storm, and the 100-year storm will be considered the Major storm.
5. No other calculation methods were used for this report.
E. Hydraulic Criteria
1. Per the DMW drainage reports the City of Fort Collins did not require
detention if the developed flows could be discharged to Spring Creek. The
existing water quality pond was designed to provide water quality for the
frequent storm and release flows exceeding the WQV, at the incoming
rate up to the elevation of the emergency overflow weir.
2. No additional drainage facility design criteria were used.
3. No modifications to any 100-year floodplain or floodway are proposed as
part of this project.
4. No modifications to any natural drainage ways are proposed as part of this
project.
5. A summary table of the DMW design flow from Lot 2 and the developed
flow from Lot 2 as a result of this project is provided below.
Lot 2 Contributing
To WCQV Pond
2-yr
(cfs)
10-yr
(cfs)
100-yr
(cfs)
DMW Design 2.42 ac 0 8.6 22.3
BEC Design 1.08 ac 1.94 9.65
F. Floodplain Regulations Compliance
1. The site is not in a floodplain or floodway.
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G. Modifications of Criteria
1. This site historically slopes to the east. In order for all of Lot 2 to drain to
the existing WQ pond in Lot 1, significant amounts of fill and retaining
walls would be required to drain pervious areas along the east and south
property line. The proposed grading plan conveys runoff from all new
impervious areas to the existing WQ pond except a small area of paving at
the new access in the northeast corner of the site which slopes toward
Midpoint Drive. As previously stated, pervious areas along the east and
south property lines currently drain south through Lot 3. The proposed
design will significantly reduce the existing pervious area draining to Lot
3, thus improving the conditions of this lot. A summary table of the
existing flows and developed flows to Lot 3 is provided below.
Lot 2 Contributing
Area to Lot 3
2-yr
(cfs)
100-yr
(cfs)
Existing 1.85 ac 0.93 4.61
Developed 0.37 ac 0.18 0.91
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. Typical historic drainage patterns for this Lot are generally to the east
toward the Larimer County Correction Center and south along the east
property line. The eastern portion of the site will be filled to direct flows
to the south and west. Developed flows will be a combination of sheet
flow, concentrated gutter flow and grass swales. The time of concentration
for the project was calculated to the sidewalk chase and curb cut on the
western side of the site. A concrete cross pan will be constructed across
the existing access from the east curb and gutter to the existing trickle pan
on the west side of the access.
2. There are no off-site flows to consider on this project site.
3. Input and Output results of the Historic Condition and Developed
Condition Fort Collins Rational Method Spreadsheet analysis are in
Appendix B. Results of the weighted Runoff Coefficients, Time of
Concentration, and minor and major storm Runoff Rates are in Appendix
C. Water Quality Control Volume and Stage Storage Table are in
Appendix D.
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4. The proposed drainage will generally follow new drainage patterns to the
south and west.
B. Specific Details
1. This site has a square shape with the low point, being on the east side
of the existing access, on the western portion of the site. Detention is not
required per the Centerpoint Plaza drainage reports prepared by DMW
Civil Engineers.
Of the 1.18 acres impacted by this project, 0.15 acres of the project will
drain a Grass Buffer and 0.83 acres of the project will drain to a Grass
Swale. These flows will combine on the west side of the project and flow
to the Water Quality Pond. Areas of landscaping adjacent to Midpoint
Drive (4,430 SF) will flow towards the street. Areas of landscaping
adjacent to the east and south property line (15,960 SF) will flow to the
south onto Lot 3. These undetained flows will remain at historic rates.
The LID requirements are met by designing a Grass Buffer behind the
proposed building to provide water quality benefits prior to entering the
detention area. The Grass Buffer is sized to treat the impervious area of the
building roof. A Grass Swale is proposed to treat the impervious area of the
delivery and drive aisles. Runoff from these areas will drain across grass
surfaces to the curb cut low point on the existing access. This will provide
additional water quality control for frequent, low intensity storms.
The new impervious area of the project draining to the WQ pond is 27,200
S.F. A minimum of 75% or 20,775 S.F. of the impervious area is required
to flow to the LID features. The project will direct 27,200 S.F. of
impervious area runoff, or 100% of runoff from the new impervious areas
to the LID features.
The LID features are sized based on 27,200 S.F. of impervious area from
the building roof and the paved areas. The area provided by the Grass
Buffer is 4,450 S.F. The area provided by the Grass Swale is 4,915 S.F.
The depth of the Grass Buffer and Grass Swell media is 18-inches.
Calculations for the Grass Buffer and Grass Swale are included in
Appendix C.
2. Detention storage & outlet design: Detention volume is not required on
this site by the City of Fort Collins as stated in the Centerpoint Plaza
Drainage Reports prepared by DMW Civil Engineers. There is an existing
water quality pond and outlet which consists of a single stage structure,
the WQCV, and then release of excess runoff at the developed runoff rate
up to the 100-yr plus WQCV elevation. WQCV of 0.085 acre-feet is
provided in addition to the LID benefits.
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3. Currently the existing outlet structure is constructed where the rim
elevation is approximately 3.54-inches above the overflow elevation of
the emergency overflow weir. The outlet structure rim elevation is also
constructed approximately 1.5-feet above the required WQCV elevation.
This project proposes to modify the existing outlet structure by cutting out
a portion of the front of the outlet box and cut the water quality plate to
the WQCV elevation. Details and calculations of the modification of the
existing outlet structure can be found in Appendix D of this report.
4. An overflow weir is designed to release flows that exceed the 100-yr
storm event runoff volume. The emergency flows are currently directed
towards an existing irrigation ditch on the north side of the railroad tracks.
As stated in the appendix of the Final Drainage Report for Centerpoint
Plaza, Phase 1, this irrigation ditch has been used for storm water
conveyance for many years and is no longer used for irrigation. The
emergency overflow conveyance will not be altered with this project.
5. Summary table: The required information can be found in Appendix C of
this report.
6. Maintenance access: The maintenance access will be from the north side
of the pond.
7. Easements: No easements are impacted as part of this project.
8. Offsite facilities: No new offsite facilities are required as part of this
project.
V. CONCLUSIONS
A. Compliance with standards
1. This report and drainage design is in compliance with all known criteria
published by the City of Fort Collins.
2. This drainage plan complies with the Spring Creek Master Plan based on
criteria conveyed from the City of Fort Collins.
3. Compliance with City floodplain regulations: This site is not in a
floodplain and no floodplains are impacted as part of this project.
4. Compliance with State & Federal regulations: This project is in
compliance with all known City, State and Federal regulations.
B. Drainage Concept
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1. The concepts put forth in this study will be effective in maintaining the
approved flow rates for this subdivision while providing adequate water
quality treatment.
2. This drainage plan complies with the City of Fort Collins Storm water
Criteria Manual and all know Master Drainage Plan recommendations.
VI. REFERENCES
1. Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted
December-2011 and February-2013.
2. Urban Storm Drainage Criteria Manual, Vol. 1, 2 and 3, Urban Drainage
and Flood Control District, Denver, Colorado, June 2001.
3. Drainage Report Addendum for Centerpoint Plaza, Phase 1, Fort Collins,
Colorado, dated November 11, 2005 by DMW Civil Engineers.
4. Drainage Report for Centerpoint Plaza, First Replat, Fort Collins,
Colorado, dated October 28, 2008 by DMW Civil Engineers.
VI. APPENDIX
A. NRCS Soils Map
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
2155 Midpoint Drive, Fort Collins,
CO
Natural
Resources
Conservation
Service
August 15, 2018
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.
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Contents
Preface.................................................................................................................... 2
Soil Map.................................................................................................................. 5
Soil Map................................................................................................................6
Legend..................................................................................................................7
Map Unit Legend.................................................................................................. 8
Map Unit Descriptions.......................................................................................... 8
Larimer County Area, Colorado...................................................................... 10
22—Caruso clay loam, 0 to 1 percent slope............................................... 10
64—Loveland clay loam, 0 to 1 percent slopes...........................................11
References............................................................................................................13
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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.
5
6
Custom Soil Resource Report
Soil Map
4490290 4490320 4490350 4490380 4490410 4490440 4490470 4490500 4490530 4490560
4490290 4490320 4490350 4490380 4490410 4490440 4490470 4490500 4490530 4490560
496740 496770 496800 496830 496860 496890 496920 496950
496740 496770 496800 496830 496860 496890 496920 496950
40° 33' 57'' N
105° 2' 18'' W
40° 33' 57'' N
105° 2' 9'' W
40° 33' 47'' N
105° 2' 18'' W
40° 33' 47'' N
105° 2' 9'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 20 40 80 120
Meters
Map Scale: 1:1,420 if printed on A portrait (8.5" x 11") 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
22 Caruso clay loam, 0 to 1
percent slope
0.9 20.7%
64 Loveland clay loam, 0 to 1
percent slopes
3.5 79.3%
Totals for Area of Interest 4.4 100.0%
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
8
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
9
Larimer County Area, Colorado
22—Caruso clay loam, 0 to 1 percent slope
Map Unit Setting
National map unit symbol: jpvt
Elevation: 4,800 to 5,500 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
Caruso and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Caruso
Setting
Landform: Flood-plain steps, stream terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 35 inches: clay loam
H2 - 35 to 44 inches: fine sandy loam, sandy loam
H2 - 35 to 44 inches: sand, gravelly sand
H3 - 44 to 60 inches:
H3 - 44 to 60 inches:
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Somewhat poorly drained
Runoff class: High
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to
moderately high (0.06 to 0.20 in/hr)
Depth to water table: About 24 to 48 inches
Frequency of flooding: Occasional
Frequency of ponding: None
Calcium carbonate, maximum in profile: 5 percent
Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0
mmhos/cm)
Available water storage in profile: High (about 9.8 inches)
Interpretive groups
Land capability classification (irrigated): 3w
Land capability classification (nonirrigated): 5w
Hydrologic Soil Group: D
Hydric soil rating: No
Custom Soil Resource Report
10
Minor Components
Loveland
Percent of map unit: 9 percent
Landform: Terraces
Hydric soil rating: Yes
Fluvaquents
Percent of map unit: 6 percent
Landform: Terraces
Hydric soil rating: Yes
64—Loveland clay loam, 0 to 1 percent slopes
Map Unit Setting
National map unit symbol: jpx9
Elevation: 4,800 to 5,500 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
Loveland and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Loveland
Setting
Landform: Flood plains, stream terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Alluvium
Typical profile
H1 - 0 to 15 inches: clay loam
H2 - 15 to 32 inches: clay loam, silty clay loam, loam
H2 - 15 to 32 inches: very gravelly sand, gravelly sand, gravelly coarse sand
H2 - 15 to 32 inches:
H3 - 32 to 60 inches:
H3 - 32 to 60 inches:
H3 - 32 to 60 inches:
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Poorly drained
Runoff class: Medium
Custom Soil Resource Report
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Capacity of the most limiting layer to transmit water (Ksat): Moderately high (0.20
to 0.60 in/hr)
Depth to water table: About 18 to 36 inches
Frequency of flooding: Occasional
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Very slightly saline to slightly saline (2.0 to 4.0
mmhos/cm)
Available water storage in profile: Very high (about 16.7 inches)
Interpretive groups
Land capability classification (irrigated): 3w
Land capability classification (nonirrigated): 3w
Hydrologic Soil Group: C
Hydric soil rating: No
Minor Components
Poudre
Percent of map unit: 5 percent
Hydric soil rating: No
Aquolls
Percent of map unit: 5 percent
Landform: Swales
Hydric soil rating: Yes
Custom Soil Resource Report
12
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
13
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
14
B. FEMA Firm Map
C. Composite C-Factor Calculations,
Time of Concentration and
Peak Flow Calculations
Rational Method Runoff Coefficients for Composite Analysis
Table RO-11 of the Fort Collins Amendments to the UDFCD Criteria Manual
Character or Surface Runoff Coefficient
Streets, Parking Lots, Drives:
Asphalt 0.95
Concrete 0.95
Gravel 0.5
Roofs 0.95
Recycled Asphalt 0.8
Lawns, Sandy Soil, Flat < 2% 0.1
Lawns, Sandy Soil, Avg 2-7% 0.15
Lawns, Sandy Soil, Steep >7% 0.2
Lawns, Heavy Soil, Flat < 2% 0.2
Lawns, Heavy Soil, Avg 2-7% 0.25
Steep >7% 0.35
Equation RO-8 of the Fort Collins Amendments to the UDFCD Criteria Manual
C=Composite Runoff Coefficient
Ci=Runoff Coefficient for Specific Area (Ai)
Ai=Area of Surface with Runoff Coefficient of Ci, acres or square feet
n=number of different surfaces to be considered
At=Total Area over which C is applicable, acres or square feet
Rational Method Runoff Coefficients for Composite Analysis - Adjustment for Infrequent Storms
Table RO-12 of the Fort Collins Amendments to the UDFCD Criteria Manual
Storm Return Period Frequency Factor, Cf
2 to 10 1.00
11 to 25 1.10
26 to 50 1.20
51 to 100 1.25
Example Calculation Table
Basin or Sub-Basin Total Area (acres)
Roof Area
(acres)
Paved Area
(acres)
Sidewalk Area
(acres)
Gravel Area
(acres)
Landscape
Area (acres)
Composite Runoff
Coefficient, C (2
to 10-yr)
Composite Runoff
Coefficient, C (11
to 25-yr)
Composite Runoff
Coefficient, C (26
to 50-yr)
Composite Runoff
Coefficient, C (
51 to 100-yr)
Lot 2 Exist 1.853 1.85 0.20 0.22 0.24 0.25
Lot 2 Dev. to WQC Pond 1.084 0.15 0.59 0.34 0.71 0.79 0.86 0.89
Lot 2 Dev. To Lot 3 0.366 0.37 0.20 0.22 0.24 0.25
Lot 2 Paved LID 0.593 0.59 0.95 1.00 1.00 1.00
Lot 2 Roof LID 0.152 0.15 0.95 1.00 1.00 1.00
Lot 2 Landscape LID 0.340 0.34 0.20 0.22 0.24 0.25
Lot 2 LID 1.084
Lot 1 Existing 2.970 0.17 0.79 0.00 2.01 0.44 0.49 0.37 0.55
Example Calculation Table
Basin or Sub-Basin
Total Area
(acres) C (2-yr) C (100-yr) Length (ft) Slope (%) Ti
(2-yr) Ti
(100-yr) Length (ft) Slope (%) Ground Cover
Velocity
(ft/sec)
(manual input) Tt
Total Tc
(2-yr) Total Tc
(100-yr)
Tc
Maximum**
for Urbanized
Basins =
(Length/180)+10 Final Tc
(2-yr)* Final Tc
(100-yr) *
Lot 2 Exist 1.85 0.20 0.25 60.00 2.00 10.35 1.15 274 0.74 PA 2.15 2.12 12.47 3.27 11.86 12.47 11.86
Lot 2 Dev. to WQC Pond 1.08 0.71 0.89 254.00 1.01 11.44 2.97 278 0.52 PL 0.23 20.14 31.58 23.12 12.96 31.58 12.96
Lot 2 Dev. To Lot 3 0.37 0.20 0.25 250.00 0.33 38.49 4.28 0 0 PA 2.15 0.00 38.49 4.28 11.39 38.49 11.39
Lot 2 Paved LID 0.59 0.95 1.00 254.00 1.01 4.46 2.97 278 0.52 PL 0.23 20.14 24.60 23.12 12.96 24.60 12.96
Lot 2 Roof LID 0.15 0.95 1.00 40.00 8.33 0.88 0.58 95 0.75 PL 0.27 5.86 6.74 6.45 10.75 6.74 6.45
Lot 2 Landscape LID 0.34 0.20 0.25 31.00 15.70 3.75 0.42 214 0.47 PL 0.21 16.98 20.73 17.40 11.36 20.73 11.36
Lot 1 Existing 2.97 0.44 0.55 50.00 1.00 8.70 1.32 400 1 PA 2.51 2.66 11.35 3.98 12.50 11.35 12.50
Total
Time of Concentration - Initial Overland Flow - Ti
C = Runoff Coefficient
Cf = Frequency Adjustment Factor
L = Length of Overland Flow (feet) (500' maximum)
S = Slope (%) (not in ft/ft)
Time of Concentration - Channelized Flow - Tt Slope (%)
Ground Cover
Type K Velocity (fps)
Ground Cover
Type K Velocity (fps)
Ground Cover
Type K Velocity (fps) Ground Cover Type
K Velocity (fps)
Ground Cover
Type K Velocity (fps)
Ground Cover
Type K Velocity (fps)
0.5 PA 1.4 1.78 GW 1.11 0.91 BG 0.7 0.35 PL 0.5 0.22 TC 0.33 0.15 HG 0.18 0.11
1 PA 1.4 2.51 GW 1.11 1.29 BG 0.7 0.50 PL 0.5 0.32 TC 0.33 0.21 HG 0.18 0.15
2 PA 1.4 3.55 GW 1.11 1.82 BG 0.7 0.71 PL 0.5 0.45 TC 0.33 0.30 HG 0.18 0.21
3 PA 1.4 4.35 GW 1.11 2.23 BG 0.7 0.87 PL 0.5 0.55 TC 0.33 0.37 HG 0.18 0.26
4 PA 1.4 5.02 GW 1.11 2.58 BG 0.7 1.00 PL 0.5 0.63 TC 0.33 0.43 HG 0.18 0.30
5 PA 1.4 5.62 GW 1.11 2.88 BG 0.7 1.12 PL 0.5 0.71 TC 0.33 0.48 HG 0.18 0.34
6 PA 1.4 6.15 GW 1.11 3.16 BG 0.7 1.23 PL 0.5 0.77 TC 0.33 0.52 HG 0.18 0.37
7 PA 1.4 6.65 GW 1.11 3.41 BG 0.7 1.33 PL 0.5 0.84 TC 0.33 0.57 HG 0.18 0.40
8 PA 1.4 7.10 GW 1.11 3.64 BG 0.7 1.42 PL 0.5 0.89 TC 0.33 0.60 HG 0.18 0.43
9 PA 1.4 7.54 GW 1.11 3.86 BG 0.7 1.50 PL 0.5 0.95 TC 0.33 0.64 HG 0.18 0.45
10 PA 1.4 7.94 GW 1.11 4.07 BG 0.7 1.58 PL 0.5 1.00 TC 0.33 0.68 HG 0.18 0.48
20 PA 1.4 11.23 GW 1.11 5.76 BG 0.7 2.24 PL 0.5 1.41 TC 0.33 0.96 HG 0.18 0.68
30 PA 1.4 13.76 GW 1.11 7.06 BG 0.7 2.75 PL 0.5 1.73 TC 0.33 1.17 HG 0.18 0.83
40 PA 1.4 15.89 GW 1.11 8.15 BG 0.7 3.17 PL 0.5 2.00 TC 0.33 1.35 HG 0.18 0.96
50 PA 1.4 17.76 GW 1.11 9.11 BG 0.7 3.54 PL 0.5 2.24 TC 0.33 1.51 HG 0.18 1.07
60 PA 1.4 19.46 GW 1.11 9.98 BG 0.7 3.88 PL 0.5 2.45 TC 0.33 1.66 HG 0.18 1.17
Example Calculation Table
Basin or Sub-Basin
Total Area
(acres) C (2-yr) C (100-yr) Tc (2-yr) Tc (100-yr) I (2-yr) I (100-yr) Q (2-yr) Q (100-yr)
Lot 2 Exist 1.85 0.20 0.25 12.5 11.9 2.50 9.96 0.93 4.61
Lot 2 Dev. to WQC Pond 1.08 0.71 0.89 31.6 13.0 2.50 9.96 1.94 9.65
Lot 2 Dev. To Lot 3 0.37 0.20 0.25 38.5 11.4 2.50 9.96 0.18 0.91
Lot 2 Paved LID 0.59 0.95 1.00 24.6 13.0 1.44 7.01 0.81 4.16
Lot 2 Roof LID 0.15 0.95 1.00 6.7 6.5 2.67 9.29 0.38 1.41
Lot 2 Landscape LID 0.34 0.20 0.25 20.7 11.4 1.59 7.42 0.11 0.63
Lot 1 Existing 2.97 0.44 0.55 11.4 12.5 2.60 7.13 3.42 11.71
Total
Basin Information Runoff Coefficients - C Time of Concentration - Tc (min) Rainfall Intensity - I (in/hr) Peak Discharge - Q (cfs)
D. WQCV Calculations,
Stage Storage Curve
Outlet Structure Modification Detail
Water Quality Capture Volume, WQCV
1. Determine the WQCV in Watershed Inches
WQCV = a (0.91I 3-1.19I 2+0.78I )
Where:
WQCV = Water Quality Capture Volume, watershed inches
a = coefficient corresponding to WQCV drain time
I = Imperviousness (%/100)
Drain Time (hrs) Coefficient (a )
12 0.8
24 0.9
40 1.0
Coefficient, a 1.00
Imperviousness, I 64
WQCV = 0.25 watershed inches
2. Determine the required storage volume in Acre-Feet
V = (WQCV/12)A
Where:
V = Required Storage Volume, acre-feet
A = Tributary catchment area upstream, acres
Area, A 4.054 acres
V = 0.085 acre-feet
Drain Time Coefficients
0.00 DATE:
0.00
0
0.00
DETENTION POND DESIGN
DRAINAGE SUMMARY
CALCULATED
WQCV REQUIRED = 4832 CF 0.111
Over ride 3707.00 0.085
5-YR STORAGE REQUIRED = 5298 CF 0.12
100-YR STORAGE REQUIRED = 26066 CF 0.60
100-YR STORAGE + WQCV REQUIRED = 30898 CF 0.71
DETENTION POND DESIGN
ASSUMPTIONS USE CONIC METHOD FOR POND SIZING Elev (ft) Area (sf) Area* (sf) Volume (cf) Sum Vol (cf)
36" RCP INV. 4910.4 0 0 0 0
4911.0 233 233 47 47 0.001
4912.0 4171 5390 1797 1843 0.041
SPILLWAY ELEV. AREA*= 4913.0 5533 14508 4836 6679 0.111
AREA1+AREA2+(AREA1xAREA2)1/2 4914.0 11422 24905 8302 14981 0.191
VOLUME* = 1/3 x depth x AREA*
CATCH BASIN GRATE ELEV 4914.25
WQCV ELEV. = 4912.63 ft DWQ= 2.23 ft
5-YR ELEV. = NA ft D5-yr= ft
100-YR + WQCV ELEV. = NA ft D100-yr +WQ= ft
OUTLET DETAIL CALCULATIONS
WQCV = 0.0851 ACRE-FT
K40 = 0.2717 =0.013D2+0.22D-0.10 D= 2.2 ft (1ft. min. depth)
a = 0.313 in2/row =WQCV / K40
Use one column of circular perforations with a hole diameter of 11/16". (Per Table OS-1 from UDFCD Manual)
CALCULATED BY:
CHECKED BY:
VOLUME CALCULATIONS
DETENTION POND
PROJECT NAME: 11/19/2018
PROJECT NUMBER:
4910.0
4910.5
4911.0
4911.5
4912.0
4912.5
4913.0
4913.5
4914.0
4914.5
-2000 0 2000 4000 6000 8000 10000 12000 14000 16000
ELEVATION
VOLUME (CF)
STORAGE VOLUME
Extended Detention Basin
Outlet Structure Orifice Sizing
1. 100-yr Orifice (using orifice equation)
a. Use Orifice Equation to solve for orifice diamter
Q = Co
A√2gh
Where:
Q = flow rate or allowable discharge, cfs
Co
= orifice coefficient, typically 0.61
A = cross-sectional area, ft
2
A0
= 88V
(0.95/H^0.085)
g = gravitational constant, 32.2 ft/sec
2
TD
S
0.09
H
(2.6/S^0.3)
h = water surface elevation minus elevation of centroid of orifice, ft
Q = 0.38 cfs
Cd = 0.61 dimensionless
h = 4.66 ft
A = 0.036 ft
2
orifice diameter = 2.57 inches
2. WQCV Perforated Orifice
a. Determine the required area per row of orifices
a = WQCV
0.013DWQ
2
+ 0.22DWQ
-0.10
Where:
Ao
= Area per row of orifices spaced on 4" centers, in
2
WQCV = Water Quality Capture Volume or "Volume", acre-ft
DWQ
= Depth of volume, ft
V = 0.085 acre-ft
DWQ
= 2.20 ft
a = 0.315 in
2
per row or from Figure EDB-3
b. Determine diameter of circular perforations
A0
= 0.315 in
2
per row
Diameter = 0.633 inches
c. Determine number of columns
Number of Columns = 1 from Table 6a-1
d. Round Orifice Diameter to nearest 1/16 inch
Area per Perforation = 0.3150 in
2
E. Reference Sheets
DMW Civil Engineers
F. Proposed Drainage Plan
Diameter per Perforation = 0.633 inches
Actual Perforation Diameter = 11/16 inches user input (round to nearest 1/16th inch)
Actual Area per Perforation = 0.3712 in
2
Actual Area per Row = 0.3712 in
2
per row
Minimum Steel Plate Thickness = 1/4 inches from Figure 5
0.0625 1/16
0.1250 1/8
0.1875 3/16
0.2500 1/4
0.3125 5/16
0.3750 3/8
0.4375 7/16
0.5000 1/2
0.5625 9/16
0.6250 5/8
0.6875 11/16
0.7500 3/4
0.8125 13/16
0.8750 7/8
0.9375 15/16
1.0000 1
e. Trach Rack Opening Width
Max Diameter of Perforations = 0.6875 inches
DWQ
= 2.20 ft
Width of Trash Rack per Column of Holes = 3 inches user input from Table 6a-1
Total Trash Rack Opening Width = 3 inches
Total Trash Rack Height = 28.4 inches
Trash Rack Design Specs = use Table 6a-2
Diameter Conversion from decimal to architectural
Micropools are typically not
allowed in Fort Collins.
Perforated orifice plate
must be configured such
that bottom orifice is at the
very bottom of the plate
and is a half perforation,
like shown.
Pond Bottom
Land Surface Types
HG Forest with Heavy Ground Litter & Meadow 0.18
TC Fallow or Minimum Tillage Cultivation 0.33
PL Short Grass Pasture & Lawns 0.5
BG Nearly Bare Ground 0.7
GW Grassed Waterway 1.11
PA Paved Area (Sheet Flow) & Shallow Gutter Flow 1.4
Total Time of Concentration (Tc
) = Initial Overland Flow (Ti
) + Channelized Flow (Tt
)
Tc
= Ti
+ Tt
**Tc Maximum (check for Urbanized Basins)
(L/180) + 10
*Tc Minimum
5 minute minimum
Basin Information Runoff Coefficients Time of Concentration - Initial Overland Flow - Ti
(minutes) Time of Concentration - Channelized Flow - Tt
(minutes) Time of Concentration - Total - Tc
(minutes)
0.10
1.00
10.00
100.00
0.1 1 10 100
Series1
Series2
Series3
Series4
Series5
Series6
Total 4.054 0.32 1.38 0.00 0.00 2.35 0.52 0.57 0.62 0.64
Basin Information Surface Type Runoff Coefficients
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 12, Oct 10, 2017
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 20, 2015—Oct
15, 2016
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
7