HomeMy WebLinkAboutMANHATTAN TOWNHOMES, SECOND FILING - PDP/FDP - FDP150021 - REPORTS - DRAINAGE REPORTJuly 29, 2015
FINAL DRAINAGE AND
EROSION CONTROL REPORT FOR
MANHATTAN TOWNHOMES, SECOND FILING
Fort Collins, Colorado
Prepared for:
Mosaic Real Estate
1021 Nightengale Dr.
Fort Collins, CO 80525
Prepared by:
301 N. Howes St., Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 1124-001
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.
July 29, 2015
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage and Erosion Control Report for
MANHATTAN TOWNHOMES, SECOND FILING
Dear Staff:
Northern Engineering is pleased to submit this Final Drainage and Erosion Control Report for your
review. This report accompanies the Project Development Plan submittal for the proposed
Manhattan Townhomes, Second Filing 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, PE
Project Engineer
Manhattan Townhomes, Second Filing
Final Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 2
C. Floodplain.......................................................................................................................................... 3
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4
A. Major Basin Description .................................................................................................................... 4
B. Sub-Basin Description ....................................................................................................................... 4
III. DRAINAGE DESIGN CRITERIA ................................................................................... 5
A. Regulations........................................................................................................................................ 5
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 5
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 6
F. Modifications of Criteria ................................................................................................................... 6
IV. DRAINAGE FACILITY DESIGN .................................................................................... 6
A. General Concept ............................................................................................................................... 6
B. Specific Details .................................................................................................................................. 7
V. CONCLUSIONS ........................................................................................................ 8
A. Compliance with Standards .............................................................................................................. 8
B. Drainage Concept .............................................................................................................................. 9
APPENDICES:
APPENDIX A.1 - Hydrologic Computations
APPENDIX A.2 - Inlet Computations
APPENDIX A.3 - Storm Line Compuations
APPENDIX A.4 - Riprap Computations
APPENDIX B.1 - Erosion Control Report
APPENDIX C.1 - Standard Operating Procedures
APPENDIX D.1 - USDA Soils Report
MAP POCKET:
Proposed Drainage Exhibit
Manhattan Townhomes, Second Filing
Final Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. The project site is located in the Northeast Quarter of Section 35, 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 southeast of the intersection of Horsetooth Rd. and
Manhattan Ave.
4. The project site lies within the Mail Creek Basin. The site is located adjacent to a
regional detention pond, which provides detention and water quality treatment for this
site as well as surrounding areas.
5. As this is an infill site, the area surrounding the site is fully developed. The existing
Park South PUD lies to just to the west of the site; South Glen PUD lies just to the
south of the site; Park South Commercial Plaza is just to the north of the site. An
existing regional detention pond and natural area exists adjacent to the site on the
east.
6. No offsite flows enter the site from the north, south, west, or east. Two offsite basins
Manhattan Townhomes, Second Filing
Final Drainage Report 2
(Basins OS1 and OS2) are identified on the Drainage Exhibit, which consist of
adjacent right of way of Manhattan Avenue that drains to the proposed inlet located in
Manhattan Avenue near the southwest corner of the site. Flows from these offsite
basins stay within right of way and do not enter the project site.
B. Description of Property
1. The development area is roughly 2.2 net acres.
Figure 1 – Aerial Photograph
2. The subject property is currently composed of vacant land. Existing ground slopes are
mild to moderate (i.e., 1 - 6±%) through the interior of the property. General
topography slopes from west to east, directing historic undeveloped flows east into the
exsiting regional detention pond adjacent to the site.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey website:
http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx,
the site consists of Nunn Clay Loam, which falls into Hydrologic Soil Group C and
Altvan-Santanta Loam, which falls into Hydrologic Soil Group B.
4. The proposed project site plan is composed of the development Townhome site.
Associated site work, water, and sewer lines will be constructed with the
development. Onsite Low Impact Design (LID) features are proposed and will consist
Manhattan Townhomes, Second Filing
Final Drainage Report 3
of several features which are discussed in Section IV, below.
Figure 2– Proposed Site Plan
5. There are no known irrigation laterals crossing the site.
6. The proposed land use is a Townhome Development.
C. Floodplain
7. No City or FEMA flood zones encroach the site or are located in vicinity of the site.
Manhattan Townhomes, Second Filing
Final Drainage Report 4
Figure 3 –City of Fort Collins GIS Floodplain Mapping
(No Flood Zones Identified)
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site lies within the Mail Creek Basin. The site is located adjacent to a
regional detention pond, which provides detention and water quality treatment for this
site as well as surrounding areas. Onsite Low Impact Design (LID) features are
proposed and will consist of several features which are discussed in Section IV,
below.
B. Sub-Basin Description
1. The subject property historically drains overland generally from west to east. Runoff
from the majority of the site has historically been collected in the existing regional
detention pond located adjacent to the site to the east.
2. A more detailed description of the project drainage patterns is provided below.
Manhattan Townhomes, Second Filing
Final Drainage Report 5
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:
Conserving existing amenities in the site including the existing vegetated areas.
Providing vegetated open areas throughout the site to reduce the overall impervious
area and to minimize directly connected impervious areas (MDCIA).
Routing flows, to the extent feasible, through vegetated swales to increase time of
concentration, promote infiltration and provide initial water quality.
Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with
Slow Release
The efforts taken in Step 1 will facilitate the reduction of runoff; however, urban
development of this intensity will still generate stormwater runoff that will require
additional BMPs and water quality. The majority of stormwater runoff from the site will
ultimately be intercepted and treated using extended detention 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:
The proposed development will provide LID and water quality treatment; thus,
eliminating sources of potential pollution previously left exposed to weathering and
runoff processes.
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:
Manhattan Townhomes, Second Filing
Final Drainage Report 6
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.
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. Please see
Appendix A.
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.
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 stated above, the subject property is not located in any City or FEMA designated
floodplains.
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 features, which are discussed further below will be provided in order to enhance
water quality of storm runoff leaving the site. Detention and water quality capture
volume for the site is provided in the adjacent regional detention pond to the east.
3. Drainage patterns anticipated for drainage basins shown in the Drainage Exhibit are
Manhattan Townhomes, Second Filing
Final Drainage Report 7
described below.
Basin 1
Basin 1 will generally drain via overland flow and via curb and gutter into Permeable
paver fields as discussed further in Section B, below. The permeable paver fields will
be designed such that minor storm flows will infiltrate into the paver systems; major
storm flows will partially infiltrate and the remainder of flows will be directed via
surface flow into the existing regional detention adjacent to the site, as shown on the
Drainage Exhibit. The permeable paver fields have been designed with underdrain
systems which daylight to the existing regional detention adjacent to the site.
Basin 2
Basin 2 will generally drain via street curb and gutter to the proposed inlet in
Manhattan Avenue to be located near the southwest corner of the site. This inlet will
capture 100-year flows and convey flow via a storm line into the existing regional
detention pond adjacent to the site.
Basin OS1 and OS2
Basins OS1 and OS2 consist of adjacent right of way of Manhattan Avenue to the
north and to the south of the site which will drain to the proposed inlet in Manhattan
Avenue located near the southwest corner of the site. Flows from these basins will
stay within the right of way of Manhattan Avenue and will not enter the project site.
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. Low Impact Design (LID) features are proposed within the site and include two
separate porous paver fields.
2. Permeable paver systems have been designed according to current City standards and
exceed current City requirements specifying a minimum of 25% of paved drive and
parking area being composed of porous pavers.
3. The paver systems have been designed with underdrain systems. The underdrain
systems have been designed to daylight to the existing regional detention pond
located adjacent to the site to the east.
4. The following table summarizes LID features and overall percentage of the basin being
treated by the proposed LID features.
Manhattan Townhomes, Second Filing
Final Drainage Report 8
50% On-Site Treatment by LID Requirement
New Impervious Area 1.599 Ac.
Paver Area 0.144 Ac.
Traditional Pavement Area 0.431 Ac.
Other Impervious Surfaces (Roofs, Concrete Walks, etc.) 1.025 Ac.
Required Minimum Impervious Area to be Treated 0.800 Ac.
Paver Treatment
Paver Area 0.144 Ac.
Run-on area for Pavers 0.351 Ac.
Impervious Area Treated by LID Pavers 0.495 Ac.
Landscape Buffer Strip
Run-on area for Landscape Strips 0.524 Ac.
Total Impervious Area Treated 1.019 Ac.
Percent of Impervious Area Treated 63.73 %
25% Permeable Pavement Requirement
New Pavement Area 25035
Sq.
Ft.
Required Minimum Area of Permeable Pavement 6259
Sq.
Ft.
Total Permeable Pavement Area 6266
Sq.
Ft.
Actual % of Permeable Pavement Provided 25.0 %
Table 1 – LID Summary Table
5. Standard Operating Procedures (SOP) Manual shall be provided to the City of
Fort Collins for review prior to Final Development Plan approval. A draft copy
of SOPs is provided in Appendix C. A final copy of the approved SOP manual
shall be provided to City by separate document and must be maintained on-
site by the entity responsible for the facility maintenance. Annual reports must
also be prepared and submitted to the City discussing the results of the
maintenance program (i.e. inspection dates, inspection frequency, volume loss
due to sedimentation, corrective actions taken, etc.).
6. Proper maintenance of the drainage facilities designed with the proposed
development is a critical component of their ongoing performance and
effectiveness.
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 Basin.
Manhattan Townhomes, Second Filing
Final Drainage Report 9
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 Basin.
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. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
APPENDIX A.1
HYDROLOGIC COMPUTATIONS
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: 1124-001
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…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf
= 1.00 100-year Cf = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Lawn, Rain
Garden, or
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
1.00 34095.00 0.78 0.34 0.06 0.00 0.00 0.38 0.61 0.61 0.76 0.50
2.00 85391.00 1.96 0.59 0.16 0.88 0.00 0.33 0.83 0.83 1.04 0.78
OS1 28500.00 0.65 0.33 0.08 0.00 0.00 0.24 0.69 0.69 0.86 0.61
OS2 2898.00 0.07 0.05 0.01 0.00 0.00 0.01 0.87 0.87 1.00 0.87
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
10-year Cf = 1.00
June 1, 2015
Overland Flow, Time of Concentration:
Project: 1124-001
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)
2-yr
Tc
Rational Method Equation: Project: 1124-001
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 0.78 13 13 12 0.61 0.61 0.76 2.02 3.45 7.16 0.96 1.64 4.27
2 2 1.96 10 10 9 0.83 0.83 1.04 2.26 3.86 8.03 3.67 6.28 16.35
OS1 OS1 0.65 15 15 14 0.69 0.69 0.86 1.90 3.24 6.71 0.85 1.45 3.76
OS2 OS2 0.07 5 5 5 0.87 0.87 1.00 2.85 4.87 9.95 0.16 0.28 0.66
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
ATC
June 1, 2015
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Q C f C i A
APPENDIX A.2
INLET COMPUTATIONS
Project: 1124‐001
By: ATC
Date: 6/1/2015
Inlet Inlet Inlet Design Design
Location Type Condition Storm Flow Inlet Capacity
(CFS) (CFS)
Manhattan Ave. Sump Single Combination Inlet Sump 100‐yr 8.70 9.20
INLET CAPACITY SUMMARY
Project =
Inlet ID =
Design Information (Input) MINOR MAJOR
Type of Inlet Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal
= 2.00 2.00 inches
Number of Unit Inlets (Grate or Curb Opening) No = 1 1
Water Depth at Flowline (outside of local depression) Flow Depth = 6.0 12.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo
(G) = 3.00 3.00 feet
Width of a Unit Grate Wo
= 2.00 2.00 feet
Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio
= 0.31 0.31
Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf
(G) = 0.50 0.50
Grate Weir Coefficient (typical value 2.15 - 3.60) Cw
(G) = 3.60 3.60
Grate Orifice Coefficient (typical value 0.60 - 0.80) Co
(G) = 0.60 0.60
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo
(C) = 3.00 3.00 feet
Height of Vertical Curb Opening in Inches Hvert
= 6.50 6.50 inches
Height of Curb Orifice Throat in Inches Hthroat
= 5.25 5.25 inches
Angle of Throat (see USDCM Figure ST-5) Theta = 0.00 0.00 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet) Wp
= 2.00 2.00 feet
Clogging Factor for a Single Curb Opening (typical value 0.10) Cf
(C) = 0.10 0.10
Curb Opening Weir Coefficient (typical value 2.3-3.6) Cw
(C) = 3.70 3.70
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co
(C) = 0.66 0.66
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 4.0 9.2 cfs
Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK) Q
PEAK REQUIRED = 2.0 8.7 cfs
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
INLET IN A SUMP OR SAG LOCATION
1124-001
Combo Inlet - Single
Denver No. 16 Combination
H-Vert
H-Curb
W
Lo (C)
Lo (G)
Wo
WP
UD Inlet 3.1-Combo.xlsm, Inlet In Sump 6/12/2015, 1:25 PM
APPENDIX A.3
STORM LINE COMPUTATIONS
You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
You created this PDF from an application that is not licensed to print to novaPDF printer (http://www.novapdf.com)
APPENDIX A.4
WATER WAWARIPRAP COMPUTATIONS
Circular
D or Da,
Pipe
Diameter
(ft)
H or Ha,
Culvert
Height
(ft)
W,
Culvert
Width
(ft)
Yt/D Q/D
1.5
Q/D
2.5 Y
t/H Q/WH
0.5
Storm Line 1 8.70 1.25 0.50 0.40 6.23 4.98 N/A N/A 2.40 4.98 1.74 5.35 Type M 6.00 8.00 2.0
Project: 1124‐001
Urban Drainage
pg MD‐107
L=
1/(2tanq)*
[At/Yt)‐W]
(ft)
Yt,
Tailwater
Depth
(ft)
Culvert Parameters
At=Q/V (ft)
CALCULATIONS FOR RIPRAP PROTECTION AT PIPE OUTLETS
Circular
Pipe
(Figure MD‐21)
Rectangular
Pipe
(Figure MD‐22) Spec
Width
of
Riprap
(ft)
2*d50,
Depth
of
Riprap
(ft)
for L/2
Froude
Parameter
Q/D
2.5
Max 6.0
or
Q/WH
1.5
Max 8.0
Riprap
DRAINAGE CRITERIA MANUAL (V. 1) MAJOR DRAINAGE
Figure MD-21—Riprap Erosion Protection at Circular Conduit Outlet Valid for Q/D
2.5 ≤ 6.0
Rev. 04/2008 MD-107
Urban Drainage and Flood Control District
MAJOR DRAINAGE DRAINAGE CRITERIA MANUAL (V. 1)
Figure MD-22—Riprap Erosion Protection at Rectangular Conduit Outlet Valid for Q/WH
1.5 ≤ 8.0
MD-108 04/2008
Urban Drainage and Flood Control District
DRAINAGE CRITERIA MANUAL (V. 1) MAJOR DRAINAGE
Figure MD-23—Expansion Factor for Circular Conduits
Rev. 04/2008 MD-109
Urban Drainage and Flood Control District
MAJOR DRAINAGE DRAINAGE CRITERIA MANUAL (V. 1)
Figure MD-24—Expansion Factor for Rectangular Conduits
MD-110 04/2008
Urban Drainage and Flood Control District
APPENDIX B.1
EROSION CONTROL REPORT
Manhattan Townhomes
Erosion Control Report
EROSION CONTROL REPORT
A comprehensive Erosion and Sediment Control Plan (along with associated details) HAS BEEN
PROVIDED BY SEPARATE DOCUMENT. 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 Plans 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 C.1
STANDARD OPERATING PROCEDURES
Page 1 of 3
STANDARD OPERATING PROCEDURES (SOPs)
MANHATTAN TOWNHOMES
A. Purpose
In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is
essential. Maintenance includes both routinely scheduled activities, as well as non-routine repairs that may be
required after large storms, or as a result of other unforeseen problems. Standard Operating Procedures (SOPs)
should clearly identify BMP maintenance responsibility. BMP maintenance is typically the responsibility of the
entity owning the BMP.
Identifying who is responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for
maintenance is critical to the long-term success of BMPs. Maintenance responsibility may be assigned either
publicly or privately. For this project, BMPs shown in Section B below noted as “Private” are to be maintained
by the property owner, homeowner’s association (HOA), or property manager.
B. Site-Specific SOPs
The following stormwater facilities contained within the Manhattan Townhomes development are subject to
SOP requirements:
- Permeable Modular Block Pavers (Private)
- Perforated Subdrain (Private)
The location of said facilities can be found on the Utility Plans and Landscape Plans for the proposed project.
Inspection and maintenance procedures and frequencies, specific maintenance requirements and activities, as
well as BMP-specific constraints and considerations shall follow the guidelines outlined in Volume 3 of the
Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual.
Page 2 of 3
Permeable Modular Block Pavers (MBPs)
There is one MBP sections associated with the project serving the purpose of reducing runoff from the site as is required
by the City per their stated LID goals and ordinances. These systems provide storage and important water quality
benefits.
Proper maintenance is critical to ensure lasting performance and integrity of the system. The more frequent and diligent
the routine maintenance procedures are, the more likely it is to avoid and/or postpone significant repair and replacement
actions. Such major remedies would include removal of the surface pavers to access (and potentially replace) the
underlying sub-base material and/or underdrain pipes should either become clogged or otherwise fail to function
properly.
For additional information on the maintenance of the Modular Block Pavers, refer to Section 5: Maintenance from
Permeable Interlocking Concrete Pavements, 4th Edition (PICP Manual) by the Interlocking Concrete Pavement Institute.
Routine Maintenance Table for Permeable Pavement Systems
Required Action Maintenance Objective Frequency of Action
Inspection
Inspect the pavement condition and
observe infiltration either during a rain
event or with a garden hose to ensure that
water infiltrates into the surface.
At least annually.
Debris Removal,
Sweeping and
Vacuuming
Use a regenerative air or vacuum sweeper
to maintain infiltration rates. Replace infill
aggregate between pavers with #8
crushed rock (3/8” washed).
As necessary - the frequency depends on use types
(e.g., foot traffic only versus vehicle traffic) and
patterns as well as specific site conditions such as
tributary basin characteristics. Minimum Annually.
Snow Removal
DO NOT apply sand to the MBP surface.
Mechanical snow and ice removal should
be used.
As necessary.
Full and Partial
Replacement of
the Pavement or
Infill Material
If the surface is completely clogged and
rendering minimal surface infiltration rate,
restoration of surface infiltration can be
achieved by removing the first ½ to 1 inch
of soiled aggregate infill material with a
vacuum sweeper. Refill the openings with
clean #8 aggregate infill materials.
Routine – Annual inspection of hydraulic and
structural facilities. Also check for obvious
problems during routine maintenance visits,
especially for plugging of outlets.
Trash Enclosure
Leakage, or other
Surface
Contamination/
Pollution
Should stormwater leach out pollutants
from the trash enclosure area, or should
other similar contaminants collect in the
paver joint filler aggregate, said material
Page 3 of 3
Perforated Subdrain Maintenance Plan
The perforated subdrain system within the Modular Block Paver (MBP) system is critical to the overall function of the
paver subbase. As such, special maintenance has been identified to ensure these perforated drain systems perform as
they were designed.
Perforated subdrains leading away from the MBP system is designed to provide faster release of water when
accumulation occurs under the MBP system. Outflow should be seen existing the riser pipe outfall at the downstream
end of the subdrain pipe. If not seen it is recommended that the system is inspected using a video camera to verify no
clogging has occurred.
Perforated subdrains leading toward the MBP system are designed to provide an opportunity for infiltration. These
subdrains often lead to a drywell where additional infiltration capacity is available to reduce runoff per the stated LID
goals adopted by the City.
Routine Maintenance Table
Required Action Maintenance Objective Frequency of Action
Inspection
Use a video camera to inspect the
condition of the perforated drain pipes.
Cleanout pipes as needed. If the integrity
of the pipe is compromised, then repair
the damaged section(s).
Every two to five years.
Inspection
Where accessible, expose inlet and/or
outlet of perforated pipe and watch for
water inflow and/or outflow.
Minimum Annually
APPENDIX D.1
USDA SOILS REPORT
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Larimer County
Natural Area, Colorado
Resources
Conservation
Service
June 11, 2015
Preface
Soil surveys contain information that affects land use planning in survey areas. They
highlight soil limitations that affect various land uses and provide information about
the properties of the soils in the survey areas. Soil surveys are designed for many
different users, including farmers, ranchers, foresters, agronomists, urban planners,
community officials, engineers, developers, builders, and home buyers. Also,
conservationists, teachers, students, and specialists in recreation, waste disposal,
and pollution control can use the surveys to help them understand, protect, or enhance
the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil properties
that are used in making various land use or land treatment decisions. The information
is intended to help the land users identify and reduce the effects of soil limitations on
various land uses. The landowner or user is responsible for identifying and complying
with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some cases.
Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/portal/
nrcs/main/soils/health/) and certain conservation and engineering applications. For
more detailed information, contact your local USDA Service Center (http://
offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic
tank absorption fields. A high water table makes a soil poorly suited to basements or
underground installations.
The National Cooperative Soil Survey is a joint effort of the United States Department
of Agriculture and other Federal agencies, State agencies including the Agricultural
Experiment Stations, and local agencies. The Natural Resources Conservation
Service (NRCS) has leadership for the Federal part of the National Cooperative Soil
Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs
and activities on the basis of race, color, national origin, age, disability, and where
applicable, sex, marital status, familial status, parental status, religion, sexual
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 alternative means
2
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..................................................................................................................7
Soil Map................................................................................................................8
Legend..................................................................................................................9
Map Unit Legend................................................................................................10
Map Unit Descriptions........................................................................................10
Larimer County Area, Colorado......................................................................12
3—Altvan-Satanta loams, 0 to 3 percent slopes.........................................12
74—Nunn clay loam, 1 to 3 percent slopes.................................................13
References............................................................................................................15
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous areas
in a specific area. They include a description of the soils and miscellaneous areas and
their location on the landscape and tables that show soil properties and limitations
affecting various uses. Soil scientists observed the steepness, length, and shape of
the slopes; the general pattern of drainage; the kinds of crops and native plants; and
the kinds of bedrock. They observed and described many soil profiles. A soil profile is
the sequence of natural layers, or horizons, in a soil. The profile extends from the
surface down into the unconsolidated material in which the soil formed or from the
surface down to bedrock. The unconsolidated material is devoid of roots and other
living organisms and has not been changed by other biological activity.
Currently, soils are mapped according to the boundaries of major land resource areas
(MLRAs). MLRAs are geographically associated land resource units that share
common characteristics related to physiography, geology, climate, water resources,
soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically
consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that is
related to the geology, landforms, relief, climate, and natural vegetation of the area.
Each kind of soil and miscellaneous area is associated with a particular kind of
landform or with a segment of the landform. By observing the soils and miscellaneous
areas in the survey area and relating their position to specific segments of the
landform, a soil scientist develops a concept, or model, of how they were formed. Thus,
during mapping, this model enables the soil scientist to predict with a considerable
degree of accuracy the kind of soil or miscellaneous area at a specific location on the
landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented by
an understanding of the soil-vegetation-landscape relationship, are sufficient to verify
predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them to
identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character of
soil properties and the arrangement of horizons within the profile. After the soil
scientists classified and named the soils in the survey area, they compared the
5
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that have
similar use and management requirements. Each map unit is defined by a unique
combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components of
the map unit. The presence of minor components in a map unit in no way diminishes
the usefulness or accuracy of the data. The delineation of such landforms and
landform segments on the map provides sufficient information for the development of
resource plans. If intensive use of small areas is planned, onsite investigation is
needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape, and
experience of the soil scientist. Observations are made to test and refine the soil-
landscape model and predictions and to verify the classification of the soils at specific
locations. Once the soil-landscape model is refined, a significantly smaller number of
measurements of individual soil properties are made and recorded. These
measurements may include field measurements, such as those for color, depth to
bedrock, and texture, and laboratory measurements, such as those for content of
sand, silt, clay, salt, and other components. Properties of each soil typically vary from
one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists interpret
the data from these analyses and tests as well as the field-observed characteristics
and the soil properties to determine the expected behavior of the soils under different
uses. Interpretations for all of the soils are field tested through observation of the soils
in different uses and under different levels of management. Some interpretations are
modified to fit local conditions, and some new interpretations are developed to meet
local needs. Data are assembled from other sources, such as research information,
production records, and field experience of specialists. For example, data on crop
yields under defined levels of management are assembled from farm records and from
field or plot experiments on the same kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on such
variables as climate and biological activity. Soil conditions are predictable over long
periods of time, but they are not predictable from year to year. For example, soil
scientists can predict with a fairly high degree of accuracy that a given soil will have
a high water table within certain depths in most years, but they cannot predict that a
high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
identified each as a specific map unit. Aerial photographs show trees, buildings, fields,
roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
6
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of soil
map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
7
8
Custom Soil Resource Report
Soil Map
4486970 4486990 4487010 4487030 4487050 4487070 4487090 4487110 4487130 4487150 4487170 4487190
4486970 4486990 4487010 4487030 4487050 4487070 4487090 4487110 4487130 4487150 4487170
492930 492950 492970 492990 493010 493030 493050 493070 493090
492930 492950 492970 492990 493010 493030 493050 493070 493090
40° 32' 7'' N
105° 5' 0'' W
40° 32' 7'' N
105° 4' 53'' W
40° 32' 0'' N
105° 5' 0'' W
40° 32' 0'' N
105° 4' 53'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,120 if printed on A portrait (8.5" x 11") sheet.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at 1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil line
placement. The maps do not show the small areas of contrasting
soils that could have been shown at a more detailed scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more accurate
calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as of
Map Unit Legend
Larimer County Area, Colorado (CO644)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
3 Altvan-Satanta loams, 0 to 3
percent slopes
1.5 41.9%
74 Nunn clay loam, 1 to 3 percent
slopes
2.0 58.1%
Totals for Area of Interest 3.5 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the soils
or miscellaneous areas in the survey area. The map unit descriptions, along with the
maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the landscape,
however, the soils are natural phenomena, and they have the characteristic variability
of all natural phenomena. Thus, the range of some observed properties may extend
beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic
class rarely, if ever, can be mapped without including areas of other taxonomic
classes. Consequently, every map unit is made up of the soils or miscellaneous areas
for which it is named and some minor components that belong to taxonomic classes
other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They generally
are in small areas and could not be mapped separately because of the scale used.
Some small areas of strongly contrasting soils or miscellaneous areas are identified
by a special symbol on the maps. If included in the database for a given area, the
contrasting minor components are identified in the map unit descriptions along with
some characteristics of each. A few areas of minor components may not have been
observed, and consequently they are not mentioned in the descriptions, especially
where the pattern was so complex that it was impractical to make enough observations
to identify all the soils and miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the usefulness
or accuracy of the data. The objective of mapping is not to delineate pure taxonomic
classes but rather to separate the landscape into landforms or landform segments that
have similar use and management requirements. The delineation of such segments
on the map provides sufficient information for the development of resource plans. If
Custom Soil Resource Report
10
intensive use of small areas is planned, however, onsite investigation is needed to
define and locate the soils and miscellaneous areas.
An identifying symbol precedes the map unit name in the map unit descriptions. Each
description includes general facts about the unit and gives important soil properties
and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major horizons
that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity,
degree of erosion, and other characteristics that affect their use. On the basis of such
differences, a soil series is divided into soil phases. Most of the areas shown on the
detailed soil maps are phases of soil series. The name of a soil phase commonly
indicates a feature that affects use or management. For example, Alpha silt loam, 0
to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps. The
pattern and proportion of the soils or miscellaneous areas are somewhat similar in all
areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present or
anticipated uses of the map units in the survey area, it was not considered practical
or necessary to map the soils or miscellaneous areas separately. The pattern and
relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-
Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas that
could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion of
the soils or miscellaneous areas in a mapped area are not uniform. An area can be
made up of only one of the major soils or miscellaneous areas, or it can be made up
of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil material
and support little or no vegetation. Rock outcrop is an example.
Custom Soil Resource Report
11
Larimer County Area, Colorado
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
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
Hydrologic Soil Group: B
Custom Soil Resource Report
12
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
74—Nunn clay loam, 1 to 3 percent slopes
Map Unit Setting
National map unit symbol: jpxn
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 and similar soils: 85 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Custom Soil Resource Report
13
Description of Nunn
Setting
Landform: Fans, 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 60 inches: clay loam, clay
H2 - 10 to 60 inches:
Properties and qualities
Slope: 1 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: High
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to
moderately high (0.06 to 0.20 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm)
Available water storage in profile: Very high (about 18.9 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: C
Custom Soil Resource Report
14
References
American Association of State Highway and Transportation Officials (AASHTO). 2004.
Standard specifications for transportation materials and methods of sampling and
testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service
FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils
in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S.
Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/soils/?cid=nrcs142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making
and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service,
U.S. Department of Agriculture Handbook 436. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/national/soils/?cid=nrcs142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://www.nrcs.usda.gov/wps/
portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuse/rangepasture/?cid=stelprdb1043084
15
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
16
MAP POCKET
DRAINAGE EXHIBITS
DR1
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
R
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
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
N O R T H E RN
PHONE: 970.221.4158
www.northernengineering.com
NORTH
C
LEGEND:
PROPOSED CONTOUR
PROPOSED STORM SEWER
PROPOSED SWALE
EXISTING CONTOUR
PROPOSED CURB & GUTTER
PROPERTY BOUNDARY
PROPOSED INLET
A
DESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
PROPOSED SWALE SECTION
1 1
NOTES:
1. REFER TO THE FINAL DRAINAGE REPORT FOR MANHATTAN TOWNHOMES BY
NORTHERN ENGINEERING, DATED JULY 29, 2015 FOR ADDITIONAL INFORMATION.
PROPOSED PERMEABLE PAVERS
PROPOSED SUBDRAIN SD
BENCHMARK
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
PROJECT DATUM: NAVD 88
City of Fort Collins Benchmark 48-01
Approximately 1/2 mile South of Horsetooth Road, West of College Avenue
at the entrance of Barnes and Noble Bookstore, in the Northeast corner of
their parking lot, on a concrete curb.
Elevation = 5036.76
City of Fort Collins Benchmark 7-93
Centerline of West Horsetooth Rd., 1/2 mile West of College Ave, on the 1/4
cor. monument.
Elevation = 5063.12
Please Note: This plan set is using NAVD 88 for a vertical datum.
Surrounding developments have used NGVD 29 Unadjusted for their vertical
datums.
If NGVD 29 Unadjusted datum is required for any purpose, the following
equation should be used:
NGVD 29 Unadjusted = NAVD 88 - 3.185'
Basis of Bearing
The Basis of Bearings is the chord distance between PC and PT along
0DQKDWWDQ$YHQXHDVEHDULQJ6RXWK
:HVW DVVXPHGEHDULQJ
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 0.78 0.61 0.76 12.8 12.4 1.0 4.3
2 2 1.96 0.83 1.04 9.8 9.3 3.7 16.4
OS1 OS1 0.65 0.69 0.86 14.8 14.4 0.9 3.8
OS2 OS2 0.07 0.87 1.00 5.1 5.0 0.2 0.7
EXISTING WETLAND
HYDROLOGY SUMMARY
LID SUMMARY
50% On-Site Treatment by LID Requirement
New Impervious Area 1.599 Ac.
Paver Area 0.144 Ac.
Traditional Pavement Area 0.431 Ac.
Other Impervious Surfaces (Roofs, Concrete Walks,
etc.) 1.025 Ac.
Required Minimum Impervious Area to be Treated 0.800 Ac.
Paver Treatment
Paver Area 0.144 Ac.
Run-on area for Pavers 0.351 Ac.
Impervious Area Treated by LID Pavers 0.495 Ac.
Landscape Buffer Strip
Run-on area for Landscape Strips 0.524 Ac.
Total Impervious Area Treated 1.019 Ac.
Percent of Impervious Area Treated 63.73 %
25% Permeable Pavement Requirement
New Pavement Area 25035 Sq. Ft.
Required Minimum Area of Permeable Pavement 6259 Sq. Ft.
Total Permeable Pavement Area 6266 Sq. Ft.
Actual % of Permeable Pavement Provided 25.0 %
the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 9, Sep 22, 2014
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr 28,
2011
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor shifting
of map unit boundaries may be evident.
Custom Soil Resource Report
9
shall be removed and properly disposed
of, and replaced with new infill aggregate.
As necessary, based on routine observation and
inspection by the professional property
management and maintenance contractor.
Type
(From
Figure
MD‐21 or
MD‐22)
By: ATC
CALCULATE
Date: 6/1/15
INPUT
Storm
Line/Culvert
Label
Design
Discharge
(cfs)
Expansion
Factor
1/(2tanq)
(From
Figure
MD‐23 or
MD‐24)
OUTPUT
Spec
Length
of
Riprap
(ft)
Box Culvert
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
11No0.25 0.25 0.31 20 2.00% 5.6 5.6 5.2 543 0.40% 1.26 7.2 0 0.00% N/A N/A 13 13 12
22No0.25 0.25 0.31 33 2.00% 7.2 7.2 6.7 311 1.00% 2.00 2.6 0 0.00% N/A N/A 10 10 9
OS1 OS1 No 0.25 0.25 0.31 20 2.00% 5.6 5.6 5.2 697 0.40% 1.26 9.2 0 0.00% N/A N/A 15 15 14
OS2 OS2 No 0.25 0.25 0.31 10 2.20% 3.9 3.9 3.6 91 0.40% 1.26 1.2 0 0.00% N/A N/A 5 5 5
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point
Basin
Overland Flow
ATC
June 1, 2015
Time of Concentration
(Equation RO-4)
3
1
1 . 87 1 . 1 *
S
Ti C Cf L