HomeMy WebLinkAboutFOSSIL CREEK APARTMENTS (FORMERLY WATERSTONE APARTMENTS) - PDP - PDP170010 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFebruary 15, 2017
PRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT FOR
FOSSIL CREEK APARTMENTS
Fort Collins, Colorado
Prepared for:
Rod Hubbard
Fossil Creek Apartments
PO Box 833
Lakeside, MO 59922
Prepared by:
301 N. Howes, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 1099-001
This Drainage Report is consciously provided as a PDF.
Please consider the environment before printing this document in its entirety.
When a hard copy is absolutely necessary, we recommend double-sided printing.
February 15, 2017
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage and Erosion Control Report for
FOSSIL CREEK APARTMENTS
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report
for your review. This report accompanies the Project Development Plan submittal for the
proposed Fossil Creek Apartments development.
This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM),
and serves to document the stormwater impacts associated with the proposed project. We
understand that review by the City is to assure general compliance with standardized criteria
contained in the FCSCM.
If you should have any questions as you review this report, please feel free to contact us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
Aaron Cvar, PhD, PE
Senior Project Engineer
Fossil Creek Apartments
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 2
C. Floodplain.......................................................................................................................................... 3
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4
A. Major Basin Description .................................................................................................................... 4
B. Sub-Basin Description ....................................................................................................................... 4
III. DRAINAGE DESIGN CRITERIA ................................................................................... 5
A. Regulations........................................................................................................................................ 5
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 6
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 6
F. Modifications of Criteria ................................................................................................................... 6
IV. DRAINAGE FACILITY DESIGN .................................................................................... 6
A. General Concept ............................................................................................................................... 6
B. Specific Details .................................................................................................................................. 8
V. CONCLUSIONS ........................................................................................................ 9
A. Compliance with Standards .............................................................................................................. 9
B. Drainage Concept .............................................................................................................................. 9
APPENDICES:
APPENDIX A – Onsite Hydrologic Computations, Offsite Hydrologic Computations
APPENDIX B - USDA Soils Information
APPENDIX C – SWMM Modeling; Detention Computations
APPENDIX D – LID Information; Water Quality Capture Volume Computations
APPENDIX E – Erosion Control Report
Fossil Creek Apartments
Preliminary Drainage Report
LIST OF FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2– Proposed Site Plan ................................................................................................ 3
Figure 3 – Existing Floodplains ............................................................................................. 4
MAP POCKET:
Proposed Drainage Exhibit
Fossil Creek Apartments
Preliminary 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 11, Township 6 North,
Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer,
State of Colorado.
3. The proposed development site is located just northwest of the intersection of
Crestridge Street and South College Avenue (State Highway 287) in Fort Collins,
Colorado.
4. The project site lies within the Fossil Creek Basin. Onsite detention is required for the
runoff volume difference between the 100-year developed inflow rate and the basin
allowable discharge rate of 0.2 cfs per acre. Additionally the site must provide water
quality treatment. Water quality treatment methods are proposed for the site, and are
described in further detail below.
5. As this is an infill site, much of the area surrounding the site is fully developed.
6. Offsite flows enter the site from the east and south. Offsite runoff peak flow rates
have been calculated, and an offsite drainage basins are shown on the Drainage
Exhibit.
Fossil Creek Apartments
Preliminary Drainage Report 2
B. Description of Property
1. The development area is roughly 14.2 net acres.
Figure 1 – Aerial Photograph
2. The subject property is currently composed of fallow ground, with ground cover
consisting of sparse natural grasses. Existing ground slopes are mild to moderate
(i.e., 1 - 6±%) through the interior of the property. General topography slopes from
south to north and northeast.
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 Kim-Thedulund Loam, and Midway Clay Loam, which fall into
Hydrologic Soil Groups B and D, respectively.
4. The proposed project site plan is composed of the development of a apartment
buildings and amenities. Associated site work, water, and sewer lines will be
constructed with the development. Onsite detention water quality treatment is
Fossil Creek Apartments
Preliminary Drainage Report 3
proposed and will consist 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 multi-family/apartments.
C. Floodplain
1. The project site is not encroached by any FEMA 100-year floodplain. The City of Fort
Collins designated Fossil Creek Flood Zone exists along the north and south sides of
the project site, as shown in Figure 3, below. This flood zone is a City-designated
floodplain; there is no FEMA designated flood zone in vicinity of the project site. The
proposed project will not involve the placement of any offsite project improvements
within the Fossil Creek Flood Zone; however the project will require storm outfalls to
be constructed within this flood zone. It is anticipated that pre- and post-construction
surveys will need to be performed and show that no placement of fill has occurred in
the floodway.
2. Portions of the site are encroached by the Fossil Creek Erosion Buffer. No site element
will be placed within the erosion buffer, with the exception of detention pond outfalls.
Detention ponds are not allowable within the erosion buffer, thus, all ponds will be
Fossil Creek Apartments
Preliminary Drainage Report 4
located outside of the buffer. However, detention pond outfall pipes are unavoidably
within the erosion buffer.
Figure 3 –Area Floodplain Mapping
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site is in the City of Fort Collins Fossil Creek Master Basin. Detention
requirements for this basin are to detain the difference between the 100-year
developed inflow rate and the historic 2-year release rate, specified as 0.20 cfs/ac.
B. Sub-Basin Description
1. The subject property historically drains overland from south to north and northeast.
Runoff from the majority of the site has historically been collected in the adjacent
Fossil Creek Apartments
Preliminary Drainage Report 5
Fossil Creek natural drainageway, and directed northeast in the drainageway.
2. A more detailed description of the project drainage patterns is provided below.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the proposed
project.
B. Four Step Process
The overall stormwater management strategy employed with the proposed project utilizes
the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters.
The following is a description of how the proposed development has incorporated each
step.
Step 1 – Employ Runoff Reduction Practices
Several techniques have been utilized with the proposed development to facilitate the
reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the
current use by implementing multiple Low Impact Development (LID) strategies including:
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 detention and LID treatment methods prior to
exiting the site.
Step 3 – Stabilize Drainageways
There are no major drainageways within the subject property. While this step may not
seem applicable to proposed development, the project indirectly helps achieve stabilized
drainageways nonetheless. By providing water quality treatment, where none previously
existed, sediment with erosion potential is removed from downstream drainageway
systems. Furthermore, this project will pay one-time stormwater development fees, as
well as ongoing monthly stormwater utility fees, both of which help achieve City-wide
drainageway stability.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
The proposed development will provide LID and water quality treatment; thus,
eliminating sources of potential pollution previously left exposed to weathering and
runoff processes.
Fossil Creek Apartments
Preliminary Drainage Report 6
C. Development Criteria Reference and Constraints
The subject property is surrounded by currently developed properties. Thus, several
constraints have been identified during the course of this analysis that will impact the
proposed drainage system including:
Existing elevations along the property lines will generally be maintained.
As previously mentioned, overall drainage patterns of the existing site will be
maintained.
Elevations of existing downstream facilities that the subject property will release to
will be maintained.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
associated with the proposed development. Tabulated data contained in Table RA-7
has been utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
3. Three separate design storms have been utilized to address distinct drainage
scenarios. A fourth design storm has also been computed for comparison purposes.
The first design storm considered is the 80th percentile rain event, which has been
employed to design the project’s water quality features. The second event analyzed is
the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The third
event considered is the “Major Storm,” which has a 100-year recurrence interval.
The fourth storm computed, for comparison purposes only, is the 10-year event.
4. No other assumptions or calculation methods have been used with this development
that are not referenced by current City of Fort Collins criteria.
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 located in a City designated floodplain. The
proposed project does not propose to modify any natural drainageways.
F. Modifications of Criteria
1. The proposed development is not requesting any modifications to criteria at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the project drainage design are to maintain existing drainage
patterns, and to ensure no adverse impacts to any adjacent properties.
2. LID treatment will be provided in pre-treatment areas upstream of detention ponds;
Fossil Creek Apartments
Preliminary Drainage Report 7
water quality will further be enhanced utilizing extended detention methods the
bottom of the detention ponds, as discussed further below. Thus, the “treatment
train” philosophy will be followed, with stormwater treatment occurring through a
variety of in-series methods prior to ultimate discharge into the Fossil Creek
drainageway.
3. Drainage patterns anticipated for drainage basins shown in the Drainage Exhibit are
described below. Drainage basins have been defined for preliminary design purposes
and are subject to change at Final design; however, general drainage patterns and
concepts are not expected to be significantly altered.
Basins 1, 2, and 6 (Detention Pond 1)
Basins 1,2, and 6 consist of apartment complex areas, parking, and landscaped
areas. These basins will generally drain via overland flow and parking lot curb and
gutter first into the proposed LID features as shown on the Drainage Exhibit, and
ultimately into Detention Pond 1. Extended detention will be provided within the
bottom stage of Pond 1, as discussed in Section IV.B, below. Please see further
discussion of water quality and LID features in Section IV.B, below.
Basin 3 and 9 (Detention Pond 2)
Basins 3 and 9 consist of apartment complex areas, parking, and landscaped areas.
These basins will generally drain via overland flow and parking lot curb and gutter first
into the proposed LID features as shown on the Drainage Exhibit, and ultimately into
Detention Pond 2. Extended detention will be provided within the bottom stage of
Pond 2, as discussed in Section IV.B, below. Please see further discussion of water
quality and LID features in Section IV.B, below.
Basins 7,8, 11 (Detention Pond 3)
Basins 7, 8, and 11 consist of apartment complex areas, parking, and landscaped
areas. These basins will generally drain via overland flow and parking lot curb and
gutter first into the proposed LID features as shown on the Drainage Exhibit, and
ultimately into Detention Pond 3. Extended detention will be provided within the
bottom stage of Pond 3, as discussed in Section IV.B, below. Please see further
discussion of water quality and LID features in Section IV.B, below.
Basins 5 and 12 (Detention Pond 4)
Basins 5 consists of apartment complex areas, parking, and landscaped areas. Basin
12 is anticipated to be developed in the future with a similar land use. These basins
will generally drain via overland flow and parking lot curb and gutter first into the
proposed LID features as shown on the Drainage Exhibit, and ultimately into Detention
Pond 4. We anticipate some form of LID pre-treatment for Basin 12, when this basin
develops in the future. Extended detention will be provided within the bottom stage of
Pond 4, as discussed in Section IV.B, below. Please see further discussion of water
quality and LID features in Section IV.B, below.
Basin 4 (Undetained)
Basin 4 consists of a portion of adjacent Highway 287 Right of Way area (0.13 Ac.),
that will generally drain via sheet flow into the adjacent Highway 287 Right of Way
west flowline.
Fossil Creek Apartments
Preliminary Drainage Report 8
Basin 10 (Undetained)
Basin 10 consists of a portion of private drive area (0.26 Ac.), that will generally drain
via sheet flow and curb and gutter flow into the proposed storm line system that will
also provide drainage for Basin OS1b. We are requesting a variance to allow this flow
to be released undetained into Fossil Creek.
Basins OS1a and OS1b
Basins OS1a and OS1b consists primarily of offsite areas to the east of the site that do
drain onto the site. These areas will be overlot graded as shown on the Drainage
Exhibit. Storm lines have been extended to provide drainage outfalls for both currently
proposed overlot graded conditions and ultimate detention and water quality outfalls.
Pipes will be designed at Final which will allow for full 100-year undeveloped/overlot
graded conditions. The ultimate detention and water quality designs to be completed
at some point in the future will be the responsibility of the owner/developer of these
offsite areas.
Basin OS2
Basin OS2 consists of adjacent Highway 287 Right of Way area. As shown on the
ODP Drainage Exhibit, we propose to detain the adjacent half street of Highway 287
within the eastern portion of the ODP plan area. The ODP plan has accounted for this
drainage in the release rate from future planned ponds conceptually shown on the
ODP Drainage Exhibit. Future design of all ponds shown will conform to release rate
criteria for the Fossil Creek Master Basin.
Basin OS3
Basin OS3 consists of offsite areas to the south of the site that will drain into the site,
consistent with historic drainage patterns. Runoff from this basin will be directed
ultimately into Detention Pond 4, and will pass through the emergency pond spillway
of Pond 4. We will not detain runoff from this basin.
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. Four detention ponds are proposed within the site and will detain up to the
100-year storm event and release at or below the allowable (for Fossil Creek
Basin) runoff rate of 0.20 cfs per acre. The ponds have been modeled utilizing
the computer program EPA SWMM 5. Please see SWMM modeling results
provided in Table 1, below, and SWMM modeling output provided in Appendix
C.
2. LID pre-treatment involving underground chamber systems, porous pavement,
and rain gardens are currently proposed in this preliminary design to treat
storm runoff prior to discharging into proposed detention ponds. The proposed
design intends to provide a “treatment train” of LID pre-treatment features
prior to discharge into detention ponds. We intend to meet or exceed the LID
treatment requirement of 75% of new impervious area. Additionally, Each
detention pond will also provide water quality capture volume for 50% of the
area draining to that pond. Please see the Drainage Exhibit for locations of
proposed LID treatment features.
Fossil Creek Apartments
Preliminary Drainage Report 9
3. Please see preliminary LID information and Water Quality Capture Volume
(Extended Detention) computations provided in Appendix D.
Table 1 - SWMM Modeling Output and Extended Detention Volume Summary
Pond ID
100-YR
Detention
Volume
(AC-FT)
Extended
Detention
Volume
(AC-FT)
Total
Req'd
Volume
(AC-FT)
Peak
Release
1 1.43 0.10 1.54 2.30
2 0.57 0.04 0.61 0.05
3 0.99 0.06 1.05 0.05
4 2.02 0.13 2.15 1.58
4. Final design details, and construction documentation shall be provided to the
City of Fort Collins for review prior to Final Development Plan approval.
5. Stormwater facility Standard Operating Procedures (SOP) will be provided by
the City of Fort Collins in the Development Agreement.
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 Fossil
Creek Basin.
3. The drainage plan and stormwater management measures proposed with the
proposed development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit any potential
damage associated with its stormwater runoff by providing detention and water
quality mitigation features.
2. The drainage concept for the proposed development is consistent with requirements
for the Fossil Creek Basin.
Fossil Creek Apartments
Preliminary Drainage Report 10
References
1. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No.
174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code.
2. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
4. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
APPENDIX A
Onsite Hydrologic Computations, Offsite Hydrologic Computations
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: 1099-001
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 85648 1.97 0.37 0.14 0.63 0.00 0.82 0.66 0.66 0.82 54.3%
2 69749 1.60 0.00 0.28 0.25 0.00 1.07 0.48 0.48 0.60 29.9%
3 72279 1.66 0.37 0.23 0.43 0.00 0.64 0.68 0.68 0.85 57.5%
4 5537 0.13 0.00 0.03 0.00 0.00 0.10 0.42 0.42 0.53 22.2%
5 90209 2.07 0.81 0.16 0.57 0.00 0.53 0.77 0.77 0.96 71.0%
6 125594 2.88 1.33 0.21 0.76 0.00 0.59 0.81 0.81 1.01 76.3%
7 113585 2.61 0.32 0.08 0.50 0.29 1.41 0.46 0.46 0.58 36.8%
8 37253 0.86 0.00 0.00 0.00 0.00 0.86 0.25 0.25 0.31 0.0%
9 11352 0.26 0.14 0.04 0.00 0.00 0.08 0.73 0.73 0.92 67.5%
Overland Flow, Time of Concentration:
Project: 1099-001
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = T
i + Tt
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
NOTE: First design point time of concentration, "Check Tc" column, per Equation 6-5, USDCM, Volume 1, January 2017.
Overland Flow Gutter Flow Swale Flow
Is Length
>500' ?
C5 Length,
L
(ft)
Slope,
S
(%)
Ti
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Tc
(min)
Check
Tc
(min)
Final
Tc
(min)
1 1 No 0.25 70 7.00% 6.8 390 5.00% 4.47 1.5 0 0.00% N/A N/A 8.3 11.2 8.3
2 2 No 0.25 110 5.00% 9.6 460 1.00% 2.00 3.8 0 0.00% N/A N/A 13.4 17.2 13.4
3 3 No 0.25 45 4.00% 6.6 310 3.00% 3.46 1.5 0 0.00% N/A N/A 8.1 10.7 8.1
4 4 No 0.25 60 5.00% 7.1 0 0.00% N/A N/A 0 0.00% N/A N/A 7.1 14.9 7.1
5 5 No 0.25 50 4.00% 6.9 390 2.00% 2.83 2.3 0 0.00% N/A N/A 9.2 9.0 9.0
Rational Method Equation: Project: 1099-001
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 1.97 8 0.66 0.66 0.82 2.40 4.10 8.38 3.10 5.30 13.55
2 2 1.60 13 0.48 0.48 0.60 1.98 3.39 6.92 1.53 2.62 6.69
3 3 1.66 8 0.68 0.68 0.85 2.40 4.10 8.38 2.71 4.63 11.82
4 4 0.13 7 0.42 0.42 0.53 2.52 4.31 8.80 0.14 0.23 0.59
5 5 2.07 9 0.77 0.77 0.96 2.30 3.93 8.03 3.67 6.28 16.03
6 6 2.88 8 0.81 0.81 1.01 2.40 4.10 8.38 5.59 9.55 24.39
7 7 2.61 10 0.46 0.46 0.58 2.21 3.78 7.72 2.67 4.57 11.67
8 8 0.86 10 0.25 0.25 0.31 2.21 3.78 7.72 0.47 0.81 2.06
9 9 0.26 6 0.73 0.73 0.92 2.76 4.72 9.63 0.53 0.90 2.31
10 10 0.12 6 0.81 0.81 1.02 2.76 4.72 9.63 0.27 0.46 1.16
11 11 0.68 7 0.57 0.57 0.71 2.60 4.44 9.06 1.00 1.71 4.36
12 12 5.09 19 0.29 0.29 0.36 1.68 2.86 5.84 2.46 4.20 10.72
OS1a OS1a 1.45 12 0.29 0.29 0.36 2.09 3.57 7.29 0.87 1.49 3.80
OS1b OS1b 5.58 14 0.29 0.29 0.36 1.95 3.34 6.82 3.14 5.38 13.71
OS2 OS2 1.87 11 0.81 0.81 1.01 2.17 3.71 7.57 3.28 5.60 14.31
OS3 OS3 2.55 10 0.44 0.44 0.55 2.26 3.86 7.88 2.53 4.32 11.03
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
ATC
February 15, 2017
Q C f C i A
APPENDIX B
USDA Soils Information
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Larimer County
Natural Area, Colorado
Resources
Conservation
Service
February 6, 2017
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface.................................................................................................................... 2
How Soil Surveys Are Made..................................................................................5
Soil Map.................................................................................................................. 8
Soil Map................................................................................................................9
Legend................................................................................................................10
Map Unit Legend................................................................................................ 11
Map Unit Descriptions.........................................................................................11
Larimer County Area, Colorado...................................................................... 13
55—Kim loam, 5 to 9 percent slopes.......................................................... 13
56—Kim-Thedalund loams, 3 to 15 percent slopes.................................... 14
65—Midway clay loam, 5 to 25 percent slopes...........................................16
106—Tassel sandy loam, 3 to 25 percent slopes........................................17
108—Thedalund loam, 3 to 9 percent slopes..............................................18
References............................................................................................................20
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
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identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
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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.
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9
Custom Soil Resource Report
Soil Map
4483880 4483940 4484000 4484060 4484120 4484180 4484240
4483880 4483940 4484000 4484060 4484120 4484180 4484240
492890 492950 493010 493070 493130 493190 493250 493310 493370 493430 493490
492890 492950 493010 493070 493130 493190 493250 493310 493370 493430 493490
40° 30' 32'' N
105° 5' 2'' W
40° 30' 32'' N
105° 4' 36'' W
40° 30' 19'' N
105° 5' 2'' W
40° 30' 19'' N
105° 4' 36'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 100 200 400 600
Feet
0 40 80 160 240
Meters
Map Scale: 1:2,870 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
Map Unit Legend
Larimer County Area, Colorado (CO644)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
55 Kim loam, 5 to 9 percent slopes 0.1 0.3%
56 Kim-Thedalund loams, 3 to 15
percent slopes
8.7 30.4%
65 Midway clay loam, 5 to 25
percent slopes
8.8 30.8%
106 Tassel sandy loam, 3 to 25
percent slopes
5.8 20.3%
108 Thedalund loam, 3 to 9 percent
slopes
5.2 18.3%
Totals for Area of Interest 28.6 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
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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,
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.
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Larimer County Area, Colorado
55—Kim loam, 5 to 9 percent slopes
Map Unit Setting
National map unit symbol: jpwz
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: Farmland of local importance
Map Unit Composition
Kim and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Kim
Setting
Landform: Fans
Landform position (three-dimensional): Base slope, side slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 7 inches: loam
H2 - 7 to 60 inches: loam, clay loam, sandy clay loam
H2 - 7 to 60 inches:
H2 - 7 to 60 inches:
Properties and qualities
Slope: 5 to 9 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm)
Available water storage in profile: Very high (about 26.5 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: B
Ecological site: Loamy Plains (R067XY002CO)
Hydric soil rating: No
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Minor Components
Thedalund
Percent of map unit: 10 percent
Hydric soil rating: No
Stoneham
Percent of map unit: 5 percent
Hydric soil rating: No
56—Kim-Thedalund loams, 3 to 15 percent slopes
Map Unit Setting
National map unit symbol: jpx0
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: Not prime farmland
Map Unit Composition
Kim and similar soils: 45 percent
Thedalund and similar soils: 35 percent
Minor components: 20 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Kim
Setting
Landform: Valley sides, fans
Landform position (three-dimensional): Side slope, base slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 7 inches: loam
H2 - 7 to 60 inches: loam, clay loam, sandy clay loam
H2 - 7 to 60 inches:
H2 - 7 to 60 inches:
Properties and qualities
Slope: 3 to 7 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
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Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm)
Available water storage in profile: Very high (about 26.5 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: B
Ecological site: Loamy Plains (R067XY002CO)
Hydric soil rating: No
Description of Thedalund
Setting
Landform position (three-dimensional): Side slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Material weathered from sandstone and shale
Typical profile
H1 - 0 to 4 inches: loam
H2 - 4 to 33 inches: clay loam, loam, sandy clay loam
H2 - 4 to 33 inches: weathered bedrock
H2 - 4 to 33 inches:
H3 - 33 to 37 inches:
Properties and qualities
Slope: 7 to 15 percent
Depth to restrictive feature: 20 to 40 inches to paralithic bedrock
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to high
(0.06 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to moderately saline (0.0 to 8.0
mmhos/cm)
Available water storage in profile: Very high (about 15.5 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: C
Ecological site: Loamy Plains (R067XY002CO)
Hydric soil rating: No
Minor Components
Renohill
Percent of map unit: 10 percent
Hydric soil rating: No
Midway
Percent of map unit: 9 percent
Hydric soil rating: No
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Aquic haplustolls
Percent of map unit: 1 percent
Landform: Swales
Hydric soil rating: Yes
65—Midway clay loam, 5 to 25 percent slopes
Map Unit Setting
National map unit symbol: jpxb
Elevation: 4,800 to 5,800 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: Not prime farmland
Map Unit Composition
Midway and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Midway
Setting
Landform position (three-dimensional): Side slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Material weathered from shale
Typical profile
H1 - 0 to 4 inches: clay loam
H2 - 4 to 19 inches: clay, clay loam, silty clay loam
H2 - 4 to 19 inches: weathered bedrock
H2 - 4 to 19 inches:
H3 - 19 to 23 inches:
Properties and qualities
Slope: 5 to 25 percent
Depth to restrictive feature: 6 to 20 inches to paralithic bedrock
Natural drainage class: Well drained
Runoff class: Very 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
Gypsum, maximum in profile: 15 percent
Salinity, maximum in profile: Very slightly saline to moderately saline (2.0 to 8.0
mmhos/cm)
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Sodium adsorption ratio, maximum in profile: 15.0
Available water storage in profile: Moderate (about 7.9 inches)
Interpretive groups
Land capability classification (irrigated): 6e
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: D
Ecological site: Shaly Plains (R067BY045CO)
Hydric soil rating: No
Minor Components
Renohill
Percent of map unit: 10 percent
Hydric soil rating: No
106—Tassel sandy loam, 3 to 25 percent slopes
Map Unit Setting
National map unit symbol: jptz
Elevation: 4,800 to 5,800 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: Not prime farmland
Map Unit Composition
Tassel and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Tassel
Setting
Landform position (three-dimensional): Side slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Material weathered from sandstone
Typical profile
H1 - 0 to 3 inches: sandy loam
H2 - 3 to 12 inches: fine sandy loam, loamy very fine sand, sandy loam
H2 - 3 to 12 inches: weathered bedrock
H2 - 3 to 12 inches:
H3 - 12 to 16 inches:
Properties and qualities
Slope: 3 to 25 percent
Depth to restrictive feature: 10 to 20 inches to paralithic bedrock
Natural drainage class: Well drained
Runoff class: Very high
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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
Available water storage in profile: Low (about 3.8 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 6s
Hydrologic Soil Group: D
Hydric soil rating: No
Minor Components
Nelson
Percent of map unit: 10 percent
Hydric soil rating: No
108—Thedalund loam, 3 to 9 percent slopes
Map Unit Setting
National map unit symbol: jpv1
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: Not prime farmland
Map Unit Composition
Thedalund and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Thedalund
Setting
Landform position (three-dimensional): Side slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Material weathered from sandstone and shale
Typical profile
H1 - 0 to 6 inches: loam
H2 - 6 to 37 inches: clay loam, loam, sandy clay loam
H2 - 6 to 37 inches: weathered bedrock
H2 - 6 to 37 inches:
H3 - 37 to 41 inches:
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Properties and qualities
Slope: 3 to 9 percent
Depth to restrictive feature: 20 to 40 inches to paralithic bedrock
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to high
(0.06 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to moderately saline (0.0 to 8.0
mmhos/cm)
Available water storage in profile: Very high (about 16.8 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: C
Ecological site: Loamy Plains (R067XY002CO)
Hydric soil rating: No
Minor Components
Kim
Percent of map unit: 6 percent
Hydric soil rating: No
Renohill
Percent of map unit: 4 percent
Hydric soil rating: No
Custom Soil Resource Report
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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
20
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
21
APPENDIX C
SWMM Modeling; Detention Computations
SWMM Detention Summary (100-YR)
Project: 1099-001
Date: 2/1/2017
By: ATC
Pond ID
Pond Volume
(CF)
Pond Volume
(AC-FT) Peak Release
1 62367.85 1.43 2.30
2 24906.65 0.57 0.05
3 43182.62 0.99 0.05
4 88155.80 2.02 1.58
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.0 (Build 5.0.015)
--------------------------------------------------------------
*********************************************************
NOTE: The summary statistics displayed in this report are
based on results found at every computational time step,
not just on results from each reporting time step.
*********************************************************
****************
Analysis Options
****************
Flow Units ............... CFS
Process Models:
Rainfall/Runoff ........ YES
Snowmelt ............... NO
Groundwater ............ NO
Flow Routing ........... YES
Water Quality .......... NO
Infiltration Method ...... HORTON
Flow Routing Method ...... KINWAVE
Starting Date ............ NOV-21-2012 00:00:00
Ending Date .............. NOV-21-2012 06:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 00:15:00
Wet Time Step ............ 00:05:00
Dry Time Step ............ 01:00:00
Routing Time Step ........ 30.00 sec
************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 6.131 3.669
Evaporation Loss ......... 0.000 0.000
Infiltration Loss ........ 0.433 0.259
Surface Runoff ........... 5.606 3.355
Final Surface Storage .... 0.137 0.082
Continuity Error (%) ..... -0.735
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 5.610 1.828
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 1.667 0.543
Internal Outflow ......... 0.000 0.000
Evaporation Loss ......... 0.000 0.000
Initial Stored Volume .... 0.000 0.000
Final Stored Volume ...... 3.943 1.285
Continuity Error (%) ..... 0.000
********************************
Highest Flow Instability Indexes
********************************
All links are stable.
*************************
Routing Time Step Summary
*************************
Minimum Time Step : 30.00 sec
Average Time Step : 30.00 sec
Maximum Time Step : 30.00 sec
Percent in Steady State : 0.00
Average Iterations per Step : 1.00
***************************
Subcatchment Runoff Summary
***************************
----------------------------------------------------------------------------------------------
Total Total Total Total Total Total Peak Runoff
Precip Runon Evap Infil Runoff Runoff Runoff Coeff
Subcatchment in in in in in 10^6 gal CFS
----------------------------------------------------------------------------------------------
SW3 3.669 0.000 0.000 0.334 3.288 0.327 34.845 0.896
SW1 3.669 0.000 0.000 0.266 3.349 0.575 60.058 0.913
SW2 3.669 0.000 0.000 0.334 3.288 0.189 20.197 0.896
SW4 3.669 0.000 0.000 0.199 3.410 0.736 75.228 0.929
--------------------------------------------------------------------------------------------
System 3.669 0.000 0.000 0.259 3.355 1.827 190.327 0.915
******************
Node Depth Summary
******************
---------------------------------------------------------------------
Average Maximum Maximum Time of Max
Depth Depth HGL Occurrence
Node Type Feet Feet Feet days hr:min
---------------------------------------------------------------------
Outlet_FC1 OUTFALL 0.00 0.00 100.00 0 00:00
Outlet_FC2 OUTFALL 0.00 0.00 100.00 0 00:00
P_3 STORAGE 6.36 7.20 108.20 0 02:51
P_1 STORAGE 5.02 6.13 107.13 0 02:08
P_2 STORAGE 4.83 5.47 106.47 0 02:41
P_4 STORAGE 5.08 5.94 106.94 0 02:13
*******************
Node InFlow Summary
*******************
-------------------------------------------------------------------------------------
Maximum Maximum Lateral Total
Lateral Total Time of Max Inflow Inflow
Inflow Inflow Occurrence Volume Volume
Node Type CFS CFS days hr:min 10^6 gal 10^6 gal
-------------------------------------------------------------------------------------
Outlet_FC1 OUTFALL 0.00 2.40 0 02:36 0.000 0.324
Outlet_FC2 OUTFALL 0.00 1.58 0 02:14 0.000 0.219
P_3 STORAGE 34.84 34.84 0 00:40 0.327 0.327
P_1 STORAGE 60.06 60.06 0 00:40 0.575 0.575
P_2 STORAGE 20.20 20.20 0 00:40 0.189 0.189
P_4 STORAGE 75.23 75.23 0 00:40 0.737 0.737
**********************
Node Surcharge Summary
**********************
Surcharging occurs when water rises above the top of the highest conduit.
---------------------------------------------------------------------
Max. Height Min. Depth
Hours Above Crown Below Rim
Node Type Surcharged Feet Feet
---------------------------------------------------------------------
P_3 STORAGE 6.01 7.199 2.801
P_1 STORAGE 6.01 6.133 3.867
P_2 STORAGE 6.01 5.467 4.533
P_4 STORAGE 6.01 5.939 4.061
*********************
SWMM 5 Page 2
Node Flooding Summary
*********************
No nodes were flooded.
**********************
Storage Volume Summary
**********************
--------------------------------------------------------------------------------------
Average Avg Maximum Max Time of Max Maximum
Volume Pcnt Volume Pcnt Occurrence Outflow
Storage Unit 1000 ft3 Full 1000 ft3 Full days hr:min CFS
--------------------------------------------------------------------------------------
P_3 36.655 44 43.185 52 0 02:51 0.05
P_1 45.609 27 62.694 38 0 02:08 2.30
P_2 21.106 25 24.908 30 0 02:41 0.05
P_4 69.970 28 88.167 35 0 02:13 1.58
***********************
Outfall Loading Summary
***********************
-----------------------------------------------------------
Flow Avg. Max. Total
Freq. Flow Flow Volume
Outfall Node Pcnt. CFS CFS 10^6 gal
-----------------------------------------------------------
Outlet_FC1 97.23 2.06 2.40 0.324
Outlet_FC2 97.23 1.39 1.58 0.219
-----------------------------------------------------------
System 97.23 3.45 3.98 0.543
********************
Link Flow Summary
********************
-----------------------------------------------------------------------------
Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence Velocity Full Full
Link Type CFS days hr:min ft/sec Flow Depth
-----------------------------------------------------------------------------
Out_3 DUMMY 0.05 0 00:55
Out_1 DUMMY 2.30 0 01:41
Out_4 DUMMY 1.58 0 02:14
Out_2 DUMMY 0.05 0 02:41
*************************
Conduit Surcharge Summary
*************************
No conduits were surcharged.
Analysis begun on: Tue Feb 07 12:42:41 2017
Analysis ended on: Tue Feb 07 12:42:41 2017
Total elapsed time: < 1 sec
SWMM 5 Page 3
Link Out_1 Flow
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Flow (CFS)
2.5
2.0
1.5
1.0
0.5
0.0
SWMM 5 Page 1
Node P_1 Volume
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Volume (ft3)
70000.0
60000.0
50000.0
40000.0
30000.0
20000.0
10000.0
0.0
SWMM 5 Page 1
Link Out_2 Flow
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Flow (CFS)
0.06
0.04
0.02
0.0
SWMM 5 Page 1
Node P_2 Volume
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Volume (ft3)
25000.0
20000.0
15000.0
10000.0
5000.0
0.0
SWMM 5 Page 1
Link Out_3 Flow
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Flow (CFS)
0.06
0.04
0.02
0.0
SWMM 5 Page 1
Node P_3 Volume
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Volume (ft3)
45000.0
40000.0
35000.0
30000.0
25000.0
20000.0
15000.0
10000.0
5000.0
0.0
SWMM 5 Page 1
Link Out_4 Flow
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Flow (CFS)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
SWMM 5 Page 1
Node P_4 Volume
Elapsed Time (hours)
0 1 2 3 4 5 6 7
Volume (ft3)
90000.0
80000.0
70000.0
60000.0
50000.0
40000.0
30000.0
20000.0
10000.0
0.0
SWMM 5 Page 1
APPENDIX D
LID Information; Water Quality Capture Volume Computations
Project: 1099-001
By: ATC
Date: 2/1/17
LID ID Basin (s) Total Basin (s)
Area (Ac.)
Basin New
Impervious Area
(Ac.)
LID
Raingarden/Chamber
System Req'd Min.
Volume (Cu.-Ft.)
RG#1 1 1.97 0.51 1670
RG#2 9 0.26 0.18 261
PS#2 3 1.66 1.02 N/A
CS#1 6 2.88 2.30 3340
CS#3 7, 11 2.99 1.21 1757
CS#4 5 2.07 1.54 2236
Total New Impervious Area Treated: 6.76 Ac.
Total New Overall Site Impervious Area: 8.33 Ac.
Percent of New Impervious Area Treated: 81.2%
75% On-Site Treatment by LID Summary Table
WATER QUALITY DESIGN CALCULATIONS
Rain Garden #1 (Pre-Treatment Pond 1)
Rain Garden Water Quality Capture Volume (12-Hr. PLD)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 1.150 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 100.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 1.0000 <-- CALCULATED
WQCV (watershed inches) = 0.400 <-- CALCULATED from Figure EDB-2
WQCV (cu-ft) = 1670 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WATER QUALITY DESIGN CALCULATIONS
Rain Garden #2 (Pre-Treatment Pond 2)
Rain Garden Water Quality Capture Volume (12-Hr. PLD)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 0.180 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 100.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 1.0000 <-- CALCULATED
WQCV (watershed inches) = 0.400 <-- CALCULATED from Figure EDB-2
WQCV (cu-ft) = 261 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WATER QUALITY DESIGN CALCULATIONS
Underground Chamber System #1 (Pre-Treatment Pond 1)
Water Quality Capture Volume (12-Hr. PLD)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 2.300 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 100.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 1.0000 <-- CALCULATED
WQCV (watershed inches) = 0.400 <-- CALCULATED from Figure EDB-2
WQCV (cu-ft) = 3340 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WATER QUALITY DESIGN CALCULATIONS
Underground Chamber System #3 (Pre-Treatment Pond 3)
Water Quality Capture Volume (12-Hr. PLD)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 1.210 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 100.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 1.0000 <-- CALCULATED
WQCV (watershed inches) = 0.400 <-- CALCULATED from Figure EDB-2
WQCV (cu-ft) = 1757 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WATER QUALITY DESIGN CALCULATIONS
Underground Chamber System #4 (Pre-Treatment Pond 4)
Water Quality Capture Volume (12-Hr. PLD)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 1.540 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 100.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 1.0000 <-- CALCULATED
WQCV (watershed inches) = 0.400 <-- CALCULATED from Figure EDB-2
WQCV (cu-ft) = 2236 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WATER QUALITY POND DESIGN CALCULATIONS
Extended Detention (Lower Stage Pond 1)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 3.160 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 80.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.8000 <-- CALCULATED
WQCV (watershed inches) = 0.328 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.104 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in2) = ** <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = ** <-- INPUT from Figure 5
n = ** <-- INPUT from Figure 5
t (in) = ** <-- INPUT from Figure 5
number of rows = ** <-- CALCULATED from WQ Depth and row spacing
**To be completed at final design
WATER QUALITY POND DESIGN CALCULATIONS
Extended Detention (Lower Stage Pond 2)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 1.055 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 80.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.8000 <-- CALCULATED
WQCV (watershed inches) = 0.328 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.035 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in2) = ** <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = ** <-- INPUT from Figure 5
n = ** <-- INPUT from Figure 5
t (in) = ** <-- INPUT from Figure 5
number of rows = ** <-- CALCULATED from WQ Depth and row spacing
**To be completed at final design
WATER QUALITY POND DESIGN CALCULATIONS
Extended Detention (Lower Stage Pond 3)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 1.830 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 80.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.8000 <-- CALCULATED
WQCV (watershed inches) = 0.328 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.060 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in2) = ** <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = ** <-- INPUT from Figure 5
n = ** <-- INPUT from Figure 5
t (in) = ** <-- INPUT from Figure 5
number of rows = ** <-- CALCULATED from WQ Depth and row spacing
**To be completed at final design
WATER QUALITY POND DESIGN CALCULATIONS
Extended Detention (Lower Stage Pond 4)
Project: 1099-001
By: ATC
Date: 2/1/17
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 3.970 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 80.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.8000 <-- CALCULATED
WQCV (watershed inches) = 0.328 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.130 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in2) = ** <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = ** <-- INPUT from Figure 5
n = ** <-- INPUT from Figure 5
t (in) = ** <-- INPUT from Figure 5
number of rows = ** <-- CALCULATED from WQ Depth and row spacing
**To be completed at final design
APPENDIX E
Erosion Control Report
Fossil Creek Apartments
Preliminary Erosion Control Report
EROSION CONTROL REPORT
A comprehensive Erosion and Sediment Control Plan (along with associated details) will be included
with the final construction drawings. It should be noted, however, that any such Erosion and
Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of
the BMPs depicted, and additional or different BMPs from those included may be necessary during
construction, or as required by the authorities having jurisdiction.
It shall be the responsibility of the Contractor to ensure erosion control measures are properly
maintained and followed. The Erosion and Sediment Control Plan is intended to be a living
document, constantly adapting to site conditions and needs. The Contractor shall update the
location of BMPs as they are installed, removed or modified in conjunction with construction
activities. It is imperative to appropriately reflect the current site conditions at all times.
The Erosion and Sediment Control Plan shall address both temporary measures to be implemented
during construction, as well as permanent erosion control protection. Best Management Practices
from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are
not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways
and inlet protection at existing and proposed storm inlets. Vehicle tracking control pads, spill
containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site
restrooms shall also be provided by the Contractor.
Grading and Erosion Control Notes can be found on the Utility Plans. The Final Plans will contain a
full-size Erosion Control sheet as well as a separate sheet dedicated to Erosion Control Details. In
addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere
to, the applicable requirements outlined in the Development Agreement for the development. Also,
the Site Contractor for this project will be required to secure a Stormwater Construction General
Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality
Control Division – Stormwater Program, prior to any earth disturbance activities. Prior to securing
said permit, the Site Contractor shall develop a comprehensive StormWater Management Plan
(SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and
document the ongoing activities, inspections, and maintenance of construction BMPs.
MAP POCKET
SWMM 5 Page 1
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: 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
10
6 6 No 0.25 40 2.00% 7.8 570 4.00% 4.00 2.4 0 0.00% N/A N/A 10.2 8.3 8.3
7 7 No 0.25 80 8.00% 7.0 530 1.80% 2.68 3.3 0 0.00% N/A N/A 10.3 15.5 10.3
8 8 No 0.25 85 6.00% 7.9 260 1.00% 2.00 2.2 0 0.00% N/A N/A 10.1 21.2 10.1
9 9 No 0.25 15 2.00% 4.8 205 2.50% 3.16 1.1 0 0.00% N/A N/A 5.9 8.7 5.9
10 10 No 0.25 15 2.00% 4.8 160 2.50% 3.16 0.8 0 0.00% N/A N/A 5.6 7.1 5.6
11 11 No 0.25 15 3.50% 4.0 540 2.50% 3.16 2.8 0 0.00% N/A N/A 6.8 14.1 6.8
12 12 No 0.25 100 2.00% 12.4 780 1.00% 2.00 6.5 0 0.00% N/A N/A 18.9 27.8 18.9
OS1a OS1a No 0.25 65 2.00% 10.0 232 1.00% 2.00 1.9 0 0.00% N/A N/A 11.9 20.7 11.9
OS1b OS1b No 0.25 60 2.00% 9.6 530 1.00% 2.00 4.4 0 0.00% N/A N/A 14.0 24.4 14.0
OS2 OS2 No 0.25 22 2.00% 5.8 1047 2.60% 3.22 5.4 0 0.00% N/A N/A 11.2 11.0 11.0
OS3 OS3 No 0.25 56 3.00% 8.1 440 3.80% 3.90 1.9 0 0.00% N/A N/A 10.0 16.5 10.0
Design
Point
Basin
ATC
February 15, 2017
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
(Equation RO-4)
3
1
. 395 1 . 1 5
S
C L
Ti
10 5186 0.12 0.05 0.04 0.00 0.00 0.02 0.81 0.81 1.02 76.7%
11 29621 0.68 0.17 0.13 0.00 0.00 0.37 0.57 0.57 0.71 43.2%
12 221918 5.09 0.00 0.28 0.00 0.00 4.81 0.29 0.29 0.36 5.0%
OS1a 62987 1.45 0.00 0.08 0.00 0.00 1.37 0.29 0.29 0.36 5.0%
OS1b 243065 5.58 0.00 0.31 0.00 0.00 5.27 0.29 0.29 0.36 5.0%
OS2 81310 1.87 0.00 1.49 0.00 0.00 0.37 0.81 0.81 1.01 72.0%
OS3 111065 2.55 0.36 0.07 0.26 0.00 1.86 0.44 0.44 0.55 25.8%
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients and Frequency Factors are taken from the City of Fort Collins amendments to the USDCM, Tables RO-11 and RO-12. % Impervious values taken from USDCM, Volume I.
10-year Cf = 1.00
February 15, 2017