HomeMy WebLinkAboutLEGACY SENIOR RESIDENCES - PDP - PDP120015 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT
LEGACY SENIOR RESIDENCES
Fort Collins, Colorado
April 30, 2012
Prepared for:
Cornerstone Associates, LLC
209 South 19th St, Suite 600
Omaha, NE 68102
Prepared by:
200 South College Avenue, Suite 100
Fort Collins, Colorado 80524
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 683-001
3 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.
April 30, 2012
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage and Erosion Control Report for
LEGACY SENIOR RESIDENCES
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report
for your review. This report accompanies the 04.30.12 Project Development Plan submittal for
the proposed Legacy Senior Residences 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 Kevin R. Brazleton, PE
Project Engineer Project Engineer
Legacy Senior Residences
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ....................................................................................................................................... 1
B. Description of Property ................................................................................................................ 1
C. Floodplain .................................................................................................................................... 3
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4
A. Major 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. Floodplain Regulations Compliance .............................................................................................. 7
G. Modifications of Criteria .............................................................................................................. 7
IV. DRAINAGE FACILITY DESIGN .................................................................................... 7
A. General Concept .......................................................................................................................... 7
B. Specific Details ............................................................................................................................. 8
V. CONCLUSIONS ........................................................................................................ 9
A. Compliance with Standards .......................................................................................................... 9
B. Drainage Concept ........................................................................................................................ 9
References ....................................................................................................................... 10
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations
B.1 – Storm Sewers (reserved for future use)
B.2 – Inlets (reserved for future use)
APPENDIX C – Water Quality Design Computations
APPENDIX D – Offsite Basins Exhibit
APPENDIX E – Erosion Control Report
Legacy Senior Residences
Preliminary Drainage Report
LIST OF TABLES AND FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2– Proposed Site Plan ................................................................................................ 3
Figure 3 – Existing Floodplains ............................................................................................. 4
Table 1 – Water Quality Pond Summary ................................................................................. 9
MAP POCKET:
C500 - Drainage Exhibit
Legacy Senior Residences
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. The project site is located in the northwest quarter of Section 12, 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 on the west side of Linden Street, the north side of Poudre
Street. The Cache La Poudre River runs just to the north of the project site.
4. The project site lies within the Downtown River District study area (Ayres, 2012), and
is located within Basin 114. This basin has a master planned outfall directly to the
Cache La Poudre river, which runs just north of the project site. Due to the project
site proximity to the river, no detention is required for onsite runoff.
5. Downtown development exists to the south and east of the site. The Aztlan
Community Center exists to the west of the project site.
B. Description of Property
1. The subject property is approximately 1.97 net acres.
Legacy Senior Residences
Preliminary Drainage Report 2
Figure 1 – Aerial Photograph
2. The subject property currently consists of open area. The ground cover generally
consists of gravel and some native seeding. Existing ground slopes are rather gentle
throughout (i.e., 2±%). General topography slopes from southwest to the northeast
towards the Cache La Poudre River.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey, the site consists of Paoli fine sandy loam,
which falls into Hydrologic Soil Group B. More site-specific exploration found varying
materials including sandy clay with occasional sand layers and sandy gravel. See the
Geotechnical Engineering Report by Terracon Consultants, Inc. for additional
information.
4. The proposed project will develop the majority of the existing site, constructing a
senior housing center. Parking areas and associated utilities will be constructed. A
water quality pond will be constructed at the northeast corner of the site.
Legacy Senior Residences
Preliminary Drainage Report 3
Figure 2– Proposed Site Plan
5. There are no irrigation ditches or related facilities in the vicinity of the project site.
6. The proposed land use is senior housing.
C. Floodplain
1. The subject property is not located in either a FEMA regulatory or City of Fort Collins
designated floodplain. The proposed outfall for the water quality pond is located
outside of the property boundary and lies within the Cache La Poudre 100-year
floodplain.
2. FEMA places the subject property within the Zone X Flood Hazard Area, which
constitutes an area determined to be outside the 0.2% annual chance floodplain.
Legacy Senior Residences
Preliminary Drainage Report 4
Figure 3 – Existing Floodplains
3. The Cache La Poudre 100-year and 500-year floodplain exist to the northeast of the
project site. FEMA FIRM Panel Number 979 for Larimer County, Dated June 17,
2008 are referenced in this study.
4. The base (100-year) flood elevation in the vicinity of the proposed structure is
4954.8, which is referenced to the City of Fort Collins NGVD 29.
5. The proposed structure is located outside of the 100-year and 500-year floodplain.
6. The Cache La Poudre half-foot floodway is located outside of the property boundary.
No fill is proposed within the half-foot floodway for construction of the offsite pond
outfall pipe.
7. It is noted that the vertical datum utilized for site survey work is the City of Fort
Collins Benchmark #4-00 (Elevation=4960.55, Ft. Collins NGVD 29).
8. A floodplain use permit will be required for the offsite pond outfall pipe within the
floodplain.
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site is located within the Downtown River District study area (Ayres,
2012), and is located within Basin 114Sub-Basin Description
2. The subject property historically drains overland towards the Cache La Poudre River,
which runs northeast of the site. A more detailed description of the project drainage
patterns follows in Section IV.A.4., below.
3. Developed areas to the southwest of the site historically drain through the project site.
Legacy Senior Residences
Preliminary Drainage Report 5
These off-site drainage flows and patterns will be maintained and accounted for with
the proposed development.
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 as athletic facilities by implementing multiple Low Impact Development (LID)
strategies including:
Conserving existing amenities in the site including the existing vegetated areas and
large trees around the perimeter of the site, particularly the north edge of the site
adjacent to East Drake Road.
Providing large 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. All stormwater runoff from the site will ultimately be
routed to the northeast corner of the site, where it is intercepted and treated in the main
water quality pond prior to exiting the site.
Step 3 – Stabilize Drainageways
There are no major drainageways in 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 where none previously existed,
sediment with erosion potential is removed from the 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.
Legacy Senior Residences
Preliminary Drainage Report 6
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project includes a senior housing center which will require the need for site
specific source controls including:
Several localized trash enclosures throughout the site for the disposal of household
waste.
C. Development Criteria Reference and Constraints
The subject property is essentially an "in-fill" development project as the property is
surrounded by currently developed properties. As such, several constraints have been
identified during the course of this analysis that will impact the proposed drainage
system including:
Existing elevations along the east and south property lines adjacent to existing
residential properties will be maintained.
Existing elevations and vegetation on the north side of the subject property will be
preserved.
Except where prohibited, grades along the existing private drive on the west side of
the subject property will 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 not located in either a FEMA regulatory or a
City of Fort Collins designated floodplain.
4. The proposed project does not propose to modify any natural drainageways.
Legacy Senior Residences
Preliminary Drainage Report 7
F. Floodplain Regulations Compliance
1. As previously mentioned, this project is not subject to any floodplain regulations.
However, extra care has been taken to ensure that neither existing nor proposed
structures will suffer damage during the 100-year storm as a result of the proposed
development.
G. 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, ensure no adverse impacts to any adjacent properties, and to maintain the
drainage concepts as outlined in the Downtown River District study (Ayres, 2012).
2. Developed areas to the southwest of the site historically drain through the project site.
These off-site drainage flows and patterns will be maintained and accounted for with
the proposed development.
3. A list of tables and figures used within this report can be found in the Table of
Contents at the front of the document. The tables and figures are located within the
sections to which the content best applies.
4. The drainage patterns anticipated for proposed drainage basins are described below.
Basin 1
Basin 1 consists of landscaped area to the rear of the proposed building and a portion
of the rooftop. The basin drains west and north into a proposed swale running along
the west side of the proposed building. The proposed swale drains to an existing
swale located to the north of the building. The existing swale drains north to the
Cache La Poudre River.
Basin 2
Basin 2 consists entirely of the rooftop of the proposed building. The basin drains into
a roof drain system to the front and rear of the building. The roof drain system drains
into the water quality pond at the northeast corner of the site.
Basin 3
Basin 3 consists mainly of the proposed parking area and the proposed water quality
pond. The basin drains via surface flow into the proposed water quality pond at the
northeast corner of the site.
The area in the southeast corner of this basin will only be graded and seeded with the
current development. In the future, it is anticipated that this area may be developed.
All runoff and water quality calculations assume a 95% imperviousness for this area to
ensure future use of the area will not be encumbered.
Legacy Senior Residences
Preliminary Drainage Report 8
Basin 4
Basin 4 consists mainly of the proposed parking area. The basin drains into a storm
drain system which drains into the proposed water quality pond at the northeast
corner of the site.
Basin 5
Basin 5 consists of a concrete drive and landscaped area to the south of the building.
The basin drains via surface flow into Poudre Street. A sidewalk chase will capture
the flows from this small basin and direct flows into the proposed swale running along
the west side of the proposed building. The proposed swale drains to an existing swale
located to the north of the proposed building. The existing swale drains north to the
Cache La Poudre River.
Basin 6
Basin 6 consists of landscaped area. The basin drains via surface sheet flow into the
Cache La Poudre River.
Basin OS1
Basin OS1 consists of developed areas to the south of the project site. Runoff from
this basin will follow existing drainage patterns, as stormwater from this basin will be
directed via the proposed swale into the existing swale to the north of the proposed
building. This existing swale is the historic concentration point for flows from this
offsite basin.
Basin OS2
Basin OS2 consists of developed areas to the south of the project site. Runoff from
this basin will be directed via surface flow into the proposed water quality pond at the
northeast corner of the site. Offsite runoff will then be captured in the outlet pipe for
the proposed water quality pond, and be directed into the Cache La Poudre River.
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. Water quality treatment is being provided for the proposed development in the form of
extended detention as previously described. Further documentation of treatment
volumes and removal rates of stormwater BMPs will be documented with the Final
Drainage Report prepared during the City FCP process.
Final design details, construction documentation, and Standard Operating
Procedures (SOP) Manual shall be provided to the City of Fort Collins for
review prior to Final Development Plan approval. A final copy of the approved
SOP manual shall be provided to City 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.).
2. Table 1, below, summarizes the water quality information for the proposed water
quality pond.
Legacy Senior Residences
Preliminary Drainage Report 9
Table 1 – Water Quality Pond Summary
Water Quality Water Quality
Pond
Spillway Top of Pond
Capture Volume WSEL Elevation Elevation
(AC-FT) (FT) (FT) (FT)
0.047 4959.20 4960.00 4960.15
3. Proper maintenance of the drainage facilities designed with the proposed
development is a critical component of their ongoing performance and effectiveness.
The water quality pond may be easily accessed by maintenance staff via the gentle
slope provided to the bottom of the pond from the south side.
4. The drainage features associated with the proposed project are all private facilities,
located on private property with the exception of the water quality pond outfall pipe.
The outfall pipe is located within Aztlan Community Center property. A drainage
easement will be dedicated for said outfall pipe to ensure that the stormwater
conveyance outfall line is protected.
5. The proposed outfall pipe will require some form of a riprap rundown to the Cache La
Poudre River. There are no other facilities or upgrades needed off-site in order to
accommodate the developed runoff from the proposed development.
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 the Downtown River
District Final Design Report (Ayres, 2012).
3. There are no regulatory floodplains within the proposed development.
4. The drainage plan and stormwater management measures proposed with the
proposed development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
5. The proposed development is in compliance with Chapter 10 of City Code.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit any potential
damage associated with its stormwater runoff by providing an extended detention
water quality pond.
2. The drainage concept for the proposed development is consistent with the Downtown
River District Final Design Report (Ayres, 2012).
Legacy Senior Residences
Preliminary Drainage Report 10
References
1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities,
November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services.
2. Fort Collins Stormwater Criteria Manual, 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.
3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
6. Downtown River District Final Design Report, February 2012, Ayres Associates.
7. Geotechnical Engineering Report, Keifer Concrete Storage Yard, February 1, 2011, Terracon
Consultants, Inc.
APPENDIX A
HYDROLOGIC COMPUTATIONS
CHARACTER OF SURFACE: Runoff
Coefficient
Percentage
Impervious Project: 683-001
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
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
1 14612 0.335 0.000 0.080 0.029 0.000 0.227 0.48 0.48 0.60 29%
2 17857 0.410 0.000 0.000 0.410 0.000 0.000 0.95 0.95 1.00 90%
3 27892 0.640 0.447 0.023 0.000 0.000 0.170 0.76 0.76 0.96 73%
4 23429 0.538 0.447 0.039 0.000 0.000 0.051 0.88 0.88 1.00 90%
5 1549 0.036 0.000 0.022 0.000 0.000 0.014 0.68 0.68 0.85 55%
6 658 0.015 0.000 0.000 0.000 0.000 0.015 0.25 0.25 0.31 0%
Overall to Pond
(Basin 2-4) 69178 1.588 0.895 0.062 0.410 0.000 0.221 0.85 0.85 1.00 83%
OS1 5408 0.124 Utilized 95% imperviousness for offsite basins OS1 and OS2 per the 0.95 0.95 1.00 95%
OS2 56991 1.308 Downtown River District master drainage study (Ayres, 2012) 0.95 0.95 1.00 95%
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.
Overland Flow, Time of Concentration:
Project: 683-001
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
Rational Method Equation: Project: 683-001
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 0.34 6 6 6 0.48 0.48 0.60 2.67 4.56 9.31 0.4 0.7 1.9
2 2 0.41 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 1.1 1.9 4.1
3 3 0.64 14 14 13 0.76 0.76 0.96 1.95 3.34 7.04 1.0 1.6 4.3
4 4 0.54 5 5 5 0.88 0.88 1.00 2.85 4.87 9.95 1.4 2.3 5.4
5 5 0.04 5 5 5 0.68 0.68 0.85 2.85 4.87 9.95 0.1 0.1 0.3
6 6 0.02 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 0.01 0.02 0.05
3
Overall to Pond
(Basin 2-4) 1.59 14 14 13 0.85 0.85 1.00 1.95 3.34 7.04 2.6 4.5 11.2
OS1 OS1 0.12 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.3 0.6 1.2
OS2 OS2 1.31 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 3.5 6.1 13.0
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
4/23/12
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
Q C f C i A
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 – Storm Sewers (reserved for future
use)
B.2 – Inlets (reserved for future use)
APPENDIX B.1
STORM SEWERS (reserved for future use)
APPENDIX B.2
INLETS (reserved for future use)
APPENDIX C
WATER QUALITY DESIGN COMPUTATIONS
WATER QUALITY POND DESIGN CALCULATIONS
Water Quality Pond
Project: 683-001
By: ATC
Date: 4.26.12
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 1.960 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 73.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.7300 <-- CALCULATED
WQCV (watershed inches) = 0.289 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.047 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in
2
) = ** <-- 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 STAGE STORAGE TABLE
Project: 683‐001
Date: 4/26/12
By: ATC
ELEV AREA CONIC CONIC CONIC
INC. VOL. TOTAL VOL. TOTAL VOL.
(FT) (SF) (CF) (CF) (AC‐FT)
4958 63 0 0 0.000
4958.2 542 53 53 0.001
4958.4 1190 169 1243 0.029
4958.6 2037 319 3280 0.075
4958.8 2661 469 5941 0.136
4959 2882 554 8823 0.203
4959.2 3065 594 11888 0.273
4959.4 3258 632 15146 0.348
4959.6 3460 672 18606 0.427
4959 4959.8 3668 712 22274 0 0.511
4960 3927 759 26201 0.601
APPENDIX D
OFFSITE BASINS EXHIBIT
APPENDIX E
EROSION CONTROL REPORT
Regency Lakeview
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.
RegencyLakeview
PreliminaryErosionControlReport
MAP POCKET
C500 – DRAINAGE EXHIBIT
X X
X
X
X
X X
X
X
X
H
Y
D
M
F
E S
D
D
BLOCK 2
OWNER:
GODINEZ
JESSE
LOT 10
OWNER:
CIENFUEGOS
JOE C
LOT 12
OWNER:
JOHNSTON
JAMES R/
JANE A
OWNER:
SANNES
JILL MARIE
OWNER:
CITY OF FORT COLLINS
(AZTLAN COMMUNITY
CENTER)
CACHE LA POUDRE RIVER
PINE STREET
(100' ROW)
POUDRE STREET
(20' ROW)
LINDEN STREET
(100' ROW)
PROPOSED
BUILDING
FFE=65.25
4" W
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD RD
RD
RD
RD
RD
RD
RD
RD
1
0.34
2
0.41
3
0.64
4
0.54
6
0.02
OS2
1.31
OS1
0.12
5
0.04
1
2
3
5
4
6
OS1
OS2
No. Revisions:
By: Date:
REVIEWED BY:
R. Provencio
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
04/30/12
PROJECT:
683-001
Sheet
Of 7 Sheets
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NOT FOR CONSTRUCTION
REVIEW SET
200 S���� C������ A�����, S���� 010 04/30/12
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E N G I N E E R I N G
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PHONE: 970.221.4158 FAX: 970.221.4159
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C500
DRAINAGE EXHIBIT
K. Brazelton
K. Brazelton
1"=20'
NORTH
( IN FEET )
1 inch = ft.
20 0 20 Feet
20
40 60
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
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R
LEGEND:
NOTES:
Date
Date
Date
Date
Date
Date
APPROVED:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
City Engineer
Water & Wastewater Utility
Stormwater Utility
Parks & Recreation
Traffic Engineer
Environmental Planner
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
WATER QUALITY POND SUMMARY
VOLUME REQ'D (ac-ft) VOLUME PROVIDED (ac-ft) POND INVERT 100-YEAR WATER SURFACE POND SPILL ELEV.
0.05 0.11 4957.95 4959.20 4960.15
PROPOSED STORM SEWER
PROPOSED STORM DRAINAGE INLET
PROPOSED CONTOURS
80
79
EXISTING STORM SEWER
PROPERTY BOUNDARY
EXISTING MAJOR CONTOUR
EXISTING MINOR CONTOUR
5015
5013
EXISTING TREES
A
DESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
BASIN
DESIGNATION
BASIN
AREA (AC)
DRAINAGE BASIN BOUNDARY
B2
1.45 ac
EXISTING RIGHT-OF-WAY
EXISTING FLOODWAY
DRAINAGE SUMMARY TABLE
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(�����)
C10 C100
10-��
T�
(���)
100-��
T�
(���)
Q10
(���)
Q100
(���)
1 1 0.34 0.48 0.60 6.4 6.0 0.7 1.9
2 2 0.41 0.95 1.00 5.0 5.0 1.9 4.1
3 3 0.64 0.76 0.96 13.7 12.8 1.6 4.3
4 4 0.54 0.88 1.00 5.0 5.0 2.3 5.4
5 5 0.04 0.68 0.85 5.0 5.0 0.1 0.3
6 6 0.02 0.25 0.31 5.0 5.0 0.0 0.0
OS1 OS1 0.12 0.95 1.00 5.0 5.0 0.6 1.2
OS2 OS2 1.31 0.95 1.00 5.0 5.0 6.1 13.0
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
11No0.25 0.25 0.31 41 12.00% 4.4 4.4 4.1 0 0.00% N/A N/A 198 1.30% 1.71 1.9 6 6 6
22No0.95 0.95 1.00 42 0.50% 2.3 2.3 1.5 214 0.50% 1.41 2.5 0 N/A N/A N/A 5 5 5
33No0.25 0.25 0.31 141 3.20% 12.8 12.8 11.9 76 0.50% 1.41 0.9 0 N/A N/A N/A 14 14 13
44No0.95 0.95 1.00 62 2.50% 1.6 1.6 1.1 67 0.50% 1.41 0.8 0 N/A N/A N/A 5 5 5
55No0.95 0.95 1.00 33 4.50% 1.0 1.0 0.7 0 0.00% N/A N/A 0 N/A N/A N/A 5 5 5
6 6 No 0.25 0.25 0.31 20 8.00% 3.6 3.6 3.3 0 0.00% N/A N/A 0 N/A N/A N/A 5 5 5
3
Overall to
Pond
(Basin 2-
4) No 0.25 0.25 0.31 141 3.20% 12.8 12.8 11.9 76 0.50% 1.41 0.9 0 N/A N/A N/A 14 14 13
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point Basin
Overland Flow
ATC
4/23/12
Time of Concentration
(Equation RO-4)
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
OS1 OS1 No 0.95 0.95 1.00 187 0.90% 4.0 4.0 2.6 202 0.40% 1.26 2.7 0 N/A N/A N/A 7 7 5
OS2 OS2 No 0.95 0.95 1.00 94 1.60% 2.3 2.3 1.6 78 0.40% 1.26 1.0 0 N/A N/A N/A 5 5 5
10-year Cf = 1.00
4/23/12