HomeMy WebLinkAboutWOVENHEARTS MEMORY CARE - PDP/FDP - 5-97A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTLOCATION MAP
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APPENDIX A
MAPS AND FIGURES
7.0 REFERENCES
1.. City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards,"
(SDDCCS), dated May 1984.
2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated March 1969, and Volume 3 dated September
1992.
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6.4 Dust Abatement
During the performance of the work or any operations appurtenant thereto, the Contractor shall
carry out proper efficient measures wherever and as necessary to reduce dust nuisance, and to
prevent dust nuisance, and to prevent dust which has originated from his operations from
damaging crops, orchards, cultivated fields, and dwellings, or causing a nuisance to persons.
The Contractor will be responsible for any damage resulting from dust originating from his
operations.
6.5 Tracking Mud on City Streets
Wherever construction vehicles access routes or intersect paved public roads, provisions must
be made to minimize the transport of sediment (mud) by runoff' or vehicles tracking onto the
paved surface. Stabilized construction entrances are required per the detail shown on the Plan,
with base material consisting of 6" coarse aggregate. The contractor will be responsible for
clearing mud tracked onto city streets on a daily basis.
6.6 Maintenance
All temporary and permanent erosion and sediment control practices must be maintained and
repaired as needed to assure continued performance of their needed function. Maintenance
is the responsibility of the contractor.
6.7 Permanent Stabilization
A vegetative cover shall be established within one and one-half years on disturbed areas
and soil stockpiles not otherwise permanently stabilized. Vegetation shall not be
considered until a ground cover is achieved which is demonstrated to be mature enough to
control soil erosion to the satisfaction of the City and to survive severe weather conditions.
Erosion control calculations, cost estimate, and schedule is included in the appendix of this
report.
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design of structural Best Management Practices. A water quality riser pipe is incorporated into
the outlet structure on the south detention pond. A water quality capture volume (including
20% additional volume for sediment storage) of 0.06 Acre-ft has been provided.
Calculations for the riser pipe are included in the appendix of this report.
6. EROSION CONTROL
6.1 Introduction
This section represents the Erosion Control Report for Wovenhearts Memory Care and was
prepared to meet the regulatory requirements of the City of Fort Collins. This report was
prepared following the guidelines and regulations set forth in the SDDCCS Manual.
The proposed improvements cover approximately eighty percent of the site. No grading is
proposed in the northwest portion of the site.
The general topography of this site consists of undisturbed soil with native vegetative ground
cover. Slopes range from one-half to one percent.
6.2 Soil Description
In accordance with the Soil Conservation Service's (SCS) "Soil Survey of Fort Collins Area,
Colorado," the soils on -site consist of the following:
Rainfall Wind Hydrologic
Soil Designation Erodibility Zone Erodibility Zone Soil Group
Nunn Clay loam Moderate Moderate
6.3 Erosion and Sediment Control Measures
C
Erosion and Sedimentation will be controlled on -site by the use of silt fence, gravel
construction entrance, and straw bale filters.
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I
DESIGN
AREA
AREA
C10 C100 Tc (10)
Tc (100)
Q (10)
Q (100)
POINT
DESIG.
(ACRES)
(MIN)
(MIN)
(CFS)
(CFS)
A
2.13
0.58
0.73
12.5
10.4
10.01
11.00
1
E
0.02
0.50
0.63
5.0
5.0
0.09
0.11
2
A+E
2.15
0.58
0.73
12.5
10.4
10.11
11.11
B
0.14
0.20
0.25
11.8
11.8
0.19
0.24
3
C
0.64
0.20
0.25
11.5
11.5
0.88
1.10
D
0.51
0.20
0.25
12.6
12.6
0.68
0.85
F
0.13
0.20
0.25
9.4
8.9
0.20
0.25
4. RUNOFF DETENTION AND RELEASE
The site will contain two detention ponds, located on the southwest and northeast portion of
the site. Both ponds are designed to detain runoff from the 100-year storm from the site. The
south pond release rate will be controlled by a box -type grated outlet with an orifice on the
outlet pipe. The north pond release rate will be controlled by an orifice on an outlet pipe.
Details of the outlets are included on the Detail Sheet in the construction plans for the site.
The 2-3/4 orifice on the outlet pipe of the south pond will restrict flows to 0.35 cfs, and the
2-1/21, orifice on the outlet pipe of the north pond will restrict flows to 0.10 cfs. The on -site
release rate is equal to 0.5 cfs/acre in accordance with the Oak/Cottonwood Farm ODP master
drainage plan and reduced by the amount of runoff that will be released undetained from the
on -site basins. Detention and release calculations include the site only. The north half of Rule
Drive adjacent to the site was excluded from calculations because due to the existing
conditions along both Rule Drive and S. Lemay Avenue, taking these flows on -site would
require extensive modification of the roadways. Typically, in this situation, the allowable
release from the site would be decreased by the amount of runoff generated by the adjacent
half -street. In this case, reducing the allowable release from this site would effectively not
allow any release from this site. Therefore flows from Rule Drive and S. Lemay Avenue have
been allowed to continue to release as historically has occurred.
Calculations are included in the appendix of this report.
5. STORMWATER QUALITY
As per The City of Fort Collins' Stormwater Utility, stormwater quality was considered in the
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I
II
II
Manual.
As stated above, the Rational Method was used for all hydrologic analyses for the project site.
The Rational Method utilizes the equation:
Q = CJCIA (1)
where Q is the flow in cfs, C is the runoff coefficient, Cf is the storm frequency adjustment
factor, I is the rainfall intensity in inches per hour, and A is the total area of the basin in acres.
The frequency adjustment factor, Cf is 1.0 for the initial 10-year storm and 1.25 for the major
100-year storm.
The appropriate rainfall intensity information was developed based on rainfall intensity -
duration curves in Figure 3-1 of this Manual.
In order to utilize the rainfall intensitycurves, the time of concentration is required. The
following equation was used to determine the time of concentration:
tt=to+tt
(2)
where t. is the time of concentration in minutes, to is the initial or overland flow time in
minutes, and t, is the travel time in the ditch, channel, or gutter in minutes. The initial or
overland flow time is calculated with the equation:
to = [1.87(1.1- CCf)Lo.sJ/(S)0.33
(3)
where L is the length of overland flow in feet (limited to a maximum of 500 feet), S is the
average slope of the basin in percent, and C and Cf are as defined previously.
All hydrologic calculations associated with the sub -basins shown are attached in the Appendix
of this report. Table 3.1 provides a summary of the design flows for all Subbasins and Design
Points (DP's) associated with this site.
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II
installed on the existing 18" storm sewer and will receive flows from the south detention pond.
The Sterling House's detention pond adds 7.5 cfs during the 100-year storm and we are adding
0.35 cfs for a total of 7.85 cfs. Calculations in the appendix of this report show that the 18"
storm sewer flowing full can carry 10.08 cfs.
Sub -basin B is a small area on the north side of the site that will not be disturbed. Runoff from
Sub -basin B is conveyed by surface flow to the existing swale along the north property line.
This area historically flows to this swale and the discharge to this swale from this site will not
be increased by this development.
Sub -basin C is a native grassed area that will have very little impervious area. Runoff from
Sub -basin C is conveyed by surface flow to the north pond. This pond discharges into the
ditch on the east property line through a 15" RCP with a 2-1/2" orifice to restrict release to
0.10 cfs.
Sub -basin D is a small area on the east side of the site. Runoff from Sub -basin D is released
undetained to the ditch along S. Lemay Avenue. The slope on the west side of the ditch will
be flattened from approximately 1.5:1 to 6:1 on the north end and 4:1 on the south end. Flows
in the ditch will not be increased due to development.
Sub -basin E is the atrium interior to the building and will be open to the outside. Runoff from
Sub -basin E is conveyed by surface flow to an inlet and piped to the southpond.
Sub -basin F is a small area along the south property line. Runoff from Sub -basin F is released
undetained to the curb and gutter on the north side of Rule Drive.
The allowable release rate for the site was determined using 0.5 cfs/acre and then decreased
by the amount of runoff that will be released undetained from this site.
On -site drainage basins are shown on the Drainage and Erosion Control Plan included in
the rear pocket of this report.
3.4 Hydrologic Analysis of the Proposed Drainage Conditions
The Rational Method was used to determine both 10-year and 100-year peak runoff values for
each Sub -basin. Runoff coefficients were assigned utilizing Table 3-2 of the SDDCCS
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2.
3.
maximum allowable release rate is 0.5 cfs / acre for sites in the McClelland Basin.
EXISTING DRAINAGE SYSTEM
2.1 Major Basin
Along the north property line, historical drainage has been concentrated in a swale from west
to east at an approximate slope of one percent. Along the east property line, a ditch carries
flow from development from the north in a southerly direction at an approximate grade of
0.25% to an existing storm sewer system under Rule Road. Along the west property line sheet
flow from Sterling House is directed southerly to an existing detention pond at an approximate
grade of 1 %. The Sterling House detention pond releases 7.5 cfs during the 100-year storm,
to an existing 18" RCP storm sewer system on the south property line of the site. Flow
continues in an easterly direction until the storm sewer connects to the storm sewer under Rule
Drive at the intersection of S. Lemay Avenue. The site has historically drained by sheet flow
from the northwest towards the southeast at an approximate slope of 0.5 —1.0 %. The entire
drainage from the site eventually enters the City's storm sewer system at the intersection of
S. Lemay Avenue and Rule Drive.
DEVELOPED FLOWS
3.1 Criteria
The Rational Method was used to determine both the 10-year and 100-year flows for the sub -
basins indicated in this drainage report. A description of the hydrologic analysis is provided
in Section 3.6 of this report.
3.2 Off -site Flows
Drainage outside of the developed area does not flow onsite.
3.3 Onsite Flows
Drainage within the developed area will surface flow to inlets and detention ponds with the
exception of three basins, which will direct discharge. All grading has been designed to carry
flows in a positive direction away from structures to the proposed drainage facilities. A
qualitative summary of the drainage patterns within each developed sub -basin is provided in
the following paragraphs. Detention and release rates are described in Section 4, "Runoff
Detention and Release".
Runoff from Sub -basin A is conveyed by surface flow to the south pond. A manhole will be
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n
1. INTRODUCTION
1.1 Project Location
The proposed Wovenhearts Memory Care is located on a tract of land situated in the Northeast
Quarter of Section 1, Township 6 North, Range 69 West of the Sixth Principal Meridian, City
of Fort Collins; County of Larimer, State of Colorado.
The site is bounded on the west by an existing development, Sterling House, on the north by
the Evangelical Covenant Church, on the east by Lemay Avenue and on the south by Rule
Drive. (See FIGURE 1 - VICINITY MAP.)
1.2 Site Characteristics
The general topography of the site consists primarily of undisturbed soil with native
vegetation. In general the site slopes to the southeast at approximately one-half to one percent.
The Soil. Survey of Larimer County Area, Colorado indicates the soils for this site are
comprised of clay loam.
1.3 Purpose and Scope of Report
This report defines the proposed drainage and erosion control plan for the proposed
Wovenhearts Memory Care assisted care living facility, including consideration of all on -site
t and off -site runoff.
1.4 Design Criteria
This report was prepared to meet or exceed the submittal requirements established in the City
of Fort Collins' "Storm Drainage Design Criteria and Construction Standards" (SDDCCS),
dated May 1984. Runoff computations were prepared for the 10-year and 100-year storm
frequency utilizing the rational method.
Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual"
(UDFCD), 1984, developed by the Denver Regional Council of Governments, has been
utilized.
1.5 Master Drainage Basin
This site is in the Oak / Cottonwood Farm ODP — McClelland Basin. The master drainage plan
for the basin was prepared by the Sear -Brown Group. According to the master plan, the
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' TABLE OF CONTENTS
PAGE
TABLE OF CONTENTS
INTRODUCTION
1.1 Project Location..............................................................................I
1.2 Site Characteristics..........................................................................1
1.3 Purpose and Scope of Report ..............................................................I
'—
1.4 Design Criteria.............................................................................. I
1.5 Master Drainage Basin...................................................................................I
—
'
2.
EXISTING DRAINAGE SYSTEM............................................................................2
2.1 Major..........................................................................................2
3.
DEVELOPED FLOWS
3.1 Criteria.....................................................................................................................2
3.2 Off -Site Flows..........................................................................................................2
3.3 Onsite Flows............................................................................................................2
3.4 Hydrologic Analysis of the Proposed Drainage Conditions....................................3
4.
RUNOFF DETENTION AND RELEASE.......................................................5
5.
STORMWATER QUALITY.......................................................................5
6.
EROSION CONTROL..............................................................................6
7. REFERENCES.......................................................................................8
APPENDIX A MAPS AND FIGURES
' APPENDIX B
HYDROLOGIC CALCULATIONS
' APPENDIX C
DETENTION POND CALCULATIONS
APPENDIX D
OUTLET STRUCTURE CALCULATIONS
' APPENDIX E
STORMWATER QUALITY CALCULATIONS
No Text
FINAL DRAINAGE AND EROSION CONTROL
STUDY
WOVENHEARTS MEMORY CARE
Prepared for:
DELWEST CORPORATION
1211 S. Parker Rd., Suite 203
Denver, CO 80231
303-671-7151
Prepared by:
JR Engineering, Ltd.
2620 East Prospect Road, Suite 190
Fort Collins, Colorado 80525
(970) 491-9888
March 3, 1998
Job Number 9182.00