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APPENDIX A
MAPS AND FIGURES
9. 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.
3. "Fossil Creek Master Drainageway Planning Study", Simons Li & Associates, Inc.,
August 1992.
4. "Final Drainage and Erosion Control Study for Miramont Valley P.U.D., Fort
Collins, Colorado", RBD, Inc. Engineering Consultants, March 18, 1996.
5. "Draft Report: Fossil Creek Stability Study - Highway 287 to Lemay Avenue",
Lidstone & Anderson, Inc., October 4, 1995.
11
8. MISCELLANEOUS
8.1 Variances
There are no variances requested with the development of VENCOR Fort Collins - Nursing
Care Center.
8.2 Irrigation Ditches
There are no irrigation ditches impacted by the development of VENCOR Fort Collins -
Nursing Care Center.
8.3 Ditch Company Approval
There are no irrigation ditches impacted by the development of VENCOR Fort Collins -
Nursing Care Center. Therefore, Ditch Company approval is not required.
8.4 Maintenance Agreements
The developer will be responsible for the maintenance of all temporary and permanent
drainage structures.
10
2. Develop practical improvements for mitigating adverse stability conditions in the
stream."
In general, this report defined the 100-year floodplain and erosion buffer limits for this
portion of Fossil Creek. As the result of this study, it was determined that no construction
is to take place within the erosion buffer limits. However, it did leave open the option of
potential improvements to Fossil Creek in order to mitigate concerns and address issues
created as the result of future development. Therefore, as part of the final development of
this site, close coordination will be required between the Developer, Engineer, City of Fort
Collins, and Lidstone & Anderson, Inc. in order to take into account the stability of Fossil
Creek.
Note: The 100-year floodplain and erosion buffer limit information shown on the attached
plans were provided to JR Engineering, Ltd. (JR) by Lidstone & Anderson, Inc (LA).
(JR performed the field survey cross sections and provided topographic information
for the preparation of the Stability Study.)
6. 500-YEAR FLOODPLAIN FOR FOSSIL CREEK
In accordance with City criteria, as this site is a "critical care facility" and located adjacent
to a Fossil Creek, the 500-year floodplain limits are shown on the attached drainage plan.
The 500-year floodplain information was provided to JR Engineering, Ltd. (JR) by Lidstone
& Anderson, Inc (LA). The information provided by LA is included in the Appendix of this
report.
7. WATER QUALITY
There are two (2) water quality ponds proposed as part of the development of VENCOR Fort
Collins - Nursing Care Center. These ponds are located in the west central and southeast
portions of this site. These ponds have been designed based on the requirements of Volume
3 of the "Urban Storm Drainage Criteria Manual". (See Appendix for calculations and
details.)
0J
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 Erosion Control
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.
4.4 Maintenance
All temporary and permanent erosion and sediment control practices must be maintained and
repaired as needed to assure continued performance of their intended function. Straw bale
dikes or silt fences will require periodic replacement. Sediment traps (behind straw bale
barriers) shall be cleaned when accumulated sediments equal approximately one-half of trap
Istorage capacity. Maintenance is the responsibility of the developer.
4.5 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
established until a ground cover is achieved which is demonstrated to be mature enough to
control soil erosion to the satisfaction of the City Inspector and to survive severe weather
conditions.
1 4.6 Variances Requested
IThere are no variances requested for erosion control for VENCOR Fort Collins - Nursing
Care Center.
' S. FOSSIL CREEK STABILITY STUDY
This portion of Fossil Creek was included in the "Draft Report: Fossil Creek Stability Study
' - Highway 287 to Lemay Avenue", Lidstone & Anderson, Inc., October 4, 1995. As stated
in this study, "The purpose of this stability study is two -fold:
1. Characterize the stability of the Fossil Creek channel between Lemay Avenue and
IHighway 287 based on an evaluation of hydrologic, hydraulic, geomorphic and
sediment transport characteristics of the stream; and
8
3.9 Storm Sewer Design
There are two underground storm sewer systems proposed with the development of
VENCOR Fort Collins - Nursing Care Center. These storm sewer pipes are the outfall for
the above referenced drainage inlets. (See Appendix for Calculations.)
4. EROSION CONTROL
4.1 Erosion and Sediment Control Measures
Erosion and sedimentation will be controlled on -site by use of inlet filters, silt fences, straw
bale barriers, gravel construction entrances, and seeding and mulch. (See the attached
Erosion Control Plan for details). The measures are designed to limit the overall sediment
yield increase due to construction as required by the City of Fort Collins. During overlot and
final grading the soil will be roughened and furrowed perpendicular to the prevailing winds.
Straw bale dikes will be placed along proposed swales. A construction schedule and erosion
control effectiveness calculations are found in the Appendix.
4.2 Dust Abatement
During the performance of the work required by these specifications or any operations
appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the
contractor shall furnish all labor, equipment, materials, and means required. The Contractor
shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance,
and to prevent dust nuisance which has originated from his operations from damaging crops,
orchards, cultivated fields, and dwellings, or causing nuisance to persons. The Contractor
will be held liable for any damage resulting from dust originating from his operations under
these specifications on right-of-way or elsewhere.
4.3 Tracking Mud on City Streets
It is unlawful to track or cause to be tracked mud or other debris onto city streets or rights -of -
way unless so ordered by the Director of Engineering in writing. Wherever construction
vehicles access routes or intersect paved public roads, provisions must be made to minimize
7
tj _ [1.87(1.1 - CCf)L0.5]/(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 on the attached drainage
plan are included 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.
DESIGN
AREA
AREA
C2
C100
Tc (2)
Tc (100)
Q (2)
Q (100)
POINT
DESIG.
(ACRES)
(MIN)
(MIN)
(CFS)
(CFS)
A
3.43
0.45
0.56
12.6
12.4
3.52
12.57
1
B
0.17
0.91
1.00
5.0
10.0
0.49
1.21
C
0.43
0.74
0.93
5.0
10.0
1.00
2.83
D
0.40
0.65
0.81
6.6
10.0
0.75
2.31
E
3.78
0.43
0.54
12.8
12.4
3.69
13.25
F
2.11
0.20
0.25
11.2
11.2
1.01
3.58
OF-1
0.02
0.20
0.25
5.0
10.0
0.01
0.04
OF-2
0.28
0.20
0.25
8.8
10.0
0.15
0.50
2
A+OF-2
3.71
0.43
0.54
12.6
12.6
3.65
12.93
3
C+D+E
4.61
0.48
0.60
12.8
11.3
5.01
18.64
3.7 Allowable Street Flow Capacities
VENCOR Fort Collins - Nursing Care Center does not affect the flows on any existing or
proposed streets. Therefore, calculations for allowable street capacities for surrounding,
existing streets are not included.
3.8 Inlet Design
There are three (3) sump condition area inlets proposed with VENCOR Fort Collins -
Nursing Care Center. These inlets are located in Subbasins B, C and D.
IRunoff from Subbasin F consists of a portion of the site along the southerly
boundary of this site. The flows from this area are conveyed southerly to Fossil
ICreek via sheet flow.
I Runoff from the combination of Subbasin OF-1 and F is routed to Fossil Creek as
stated in the previous paragraphs.
3.6 Hydrologic Analysis of the Proposed Drainage Conditions
The Rational Method was used to determine both 2-year and 100-year peak runoff values for
each Subbasin. Runoff coefficients were assigned utilizing Table 3-2 of the SDDCCS
Manual.
As stated above, the Rational Method was used for all hydrologic analyses for the project
site. The Rational Method utilizes the SDDCCS equation:
Q = C,CIA
Iwhere Q is the flow in cfs, A is the total area of the basin in acres, Cf is the storm frequency
adjustment factor, C is the runoff coefficient, and I is the rainfall intensity in inches per hour.
The frequency adjustment factor, Cf, is 1.0 for the initial 2-year storm and 1.25 for the major
I100-year storm.
The appropriate rainfall intensity information was developed based on rainfall intensity
duration curves in the SDDCCS Manual.
In order to utilize the rainfall intensity curves, the time of concentration is required. The
following equation was used to determine the time of concentration:
tC=ti+tt
(2)
where t, is the time of concentration in minutes,;t 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 SDDCCS Manual equation:
R
The proposed drainage facilities for this site consist of two proposed area (sump condition)
inlets connected two a storm sewer (pipe) and two water quality ponds that outfall into Fossil
Creek.
3.5 Proposed Drainage Plan
A qualitative summarization of the drainage patterns within each sub -basin and at each
design point is provided in the following discussion paragraphs. Discussions of the detailed
design of drainage facilities identified in this section are included in Sections 3.7.
Runoff from Subbasin OF-2 is conveyed via sheet flow onto Subbasin A
Runoff from Subbasin A is conveyed via sheet flow, swale, and gutter flow to a
proposed water quality pond located in the westerly portion of this site. Said water
quality pond outlets the flows through a proposed pipe into Fossil Creek.
Runoff from the combination of Subbasin OF-2 and A is routed to Fossil Creek as
stated in the previous paragraphs.
Runoff from Subbasin B is conveyed to a proposed sump condition area inlet in the
atrium area of the west central portion of the building, and outletted through a
proposed pipe into a proposed water quality pond located in Subbasin E.
Runoff from Subbasin C is conveyed to a proposed sump condition area inlet in the
landscaped area in the north central portion of the proposed building, and outletted
through a proposed pipe into a proposed water quality pond located in Subbasin E.
Runoff from Subbasin D is conveyed to a proposed sump condition area inlet in the
landscaped area in the northeast portion of the proposed building, and outletted
through a proposed pipe into a proposed water quality pond located in Subbasin E.
Runoff from Subbasin E is conveyed to a proposed swale along the east side of the
proposed building, diverted southerly, and conveyed in said swale to a proposed
water quality pond in the southeast portion of this site. Said water quality pond
outlets the flows through a proposed pipe into Fossil Creek.
Runoff from the combination of Subbasin B, C, D and E is routed to Fossil Creek
as stated in the previous paragraphs.
Runoff from Subbasin OF-1 is conveyed via sheet flow onto Subbasin F
4
the development of VENCOR Fort Collins - Nursing Care Center. Therefore,
historic (existing) runoff calculations are not included as part of this report.
I DEVELOPED FLOWS
3.1 Method
The Rational Method was used to determine both the 2-year and 100-year flows for the sub -
basins indicated in this drainage report. A detailed description of the hydrologic analysis is
provided in Section 3.6 of this report.
3.2 Exterior Flows
As previously discussed, exterior flows enter this site in sheet flow from a small area north
of the northwestern portion of this site. The majority of the flows from the property to the
north (Miramont Valley P.U.D.), including the extension of Southridge Greens Boulevard
along the north property line of VENCOR Fort Collins - Nursing Care Center, are diverted
to a Water Quality Pond in the southeast portion of Miramont Valley P.U.D. and released
into Mail Creek.
3.3 Onsite Flows
Flows within this site will take the form of overlot, swale, street, and pipe flow. The existing
drainage patterns have been maintained where possible. All grading has been designed to
cant' flows away from structures to the proposed drainage facilities.
3.4 General Flow Routing
The fmal drainage pattern for this area has been developed to provide a drainage system that
is compatible with the surrounding area. This has been accomplished by utilizing existing
drainage patterns to the extent possible and routing flows to limit the amount of required
drainage facilities.
3
1.4 Purpose and Scope of Report
This report defines the proposed final drainage and erosion control plan for VENCOR Fort
Collins - Nursing Care Center, including consideration of all on -site and tributary off -site
runoff.
1.5 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 2-year minor and 100-year
major 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.
1.6 Master Drainage Basin
This site is included in the "Fossil Creek Master Drainageway Planning Study", prepared by
Simons Li & Associates, Inc., August 1992. The Simons Li report is a general overview of
the area with specific improvement recommendations for Fossil Creek.
2. HISTORIC (EXISTING) DRAINAGE
The historic (existing) flows for this site consist of the flows from the site itself and two
small basins north of the northwest portion of this site. The development of Miramont
Valley P.U.D. and Southridge Greens Boulevard to the north has accommodated the majority
of the runoff that historically entered this site from the north. Information for Miramont is
included in the "Final Drainage and Erosion Control Study for Miramont Valley P.U.D., Fort
Collins, Colorado", RBD, Inc. Engineering Consultants, March 18, 1996.
Note: Detention is not required within the Fossil Creek Basin nor is it provided as part of
2
1. INTRODUCTION
1.1 Project Location
VENCOR Fort Collins - Nursing Care Center is located in the northeast one -quarter of
Section 12, Township 6 North, Range 69 West of the Sixth Principal Meridian, in the City
of Fort Collins, Larimer County, Colorado. (See VICINITY MAP in Appendix.)
This site is bounded on the north by Southridge Greens Boulevard and Miramont Valley
P.U.D., on the east by Lemay Avenue, and on the south and west by Fossil Creek and Mail
Creek.
The total site contains approximately 10.31 acres.
1.2 Site Characteristics
The site is primarily covered with native grasses. The majority of the site drains in a
southerly direction at slopes ranging from 0.5 to 7 percent.
1.3 Soils
The soils for this site are comprised of Heldt clay loam (48) and Wiley silt loam (119). (See
FIGURE 2 - SOIL MAP.)
Heldt clay loam consists of nearly level soils on fans and valley sides. Pertinent
characteristics of this soil include medium runoff, a slight hazard of wind erosion, and a
slight to moderate hazard of water erosion. Heldt clay loam is categorized in Hydrologic
Group C.
Wiley Silt loam consists of gently sloping soils on uplands. Pertinent characteristics of this
soil include medium runoff and a moderate hazard of erosion. Wiley silt loam is categorized
in Hydrologic Group B.
The source for soil data is the "Soil Survey for Larimer County Area, Colorado", prepared
by the United States Department of Agriculture Soil Conservation Service.
8.2 Irrigation Ditches ................................................. 10
8.3 Ditch Company Approval .......................................... 10
8.4 Maintenance Agreements ........................................... 10
9. REFERENCES 11
.....................
APPENDIX A - MAPS AND FIGURES
APPENDIX B - HYDROLOGIC CALCULATIONS
APPENDIX C - INLET CALCULATIONS
APPENDIX D - OUTFALL PIPE CALCULATIONS
APPENDIX E - 500-YEAR FLOODPLAIN
APPENDIX F - WATER QUALITY PONDS
APPENDIX G - EROSION CONTROL
ii
TABLE OF CONTENTS
PAGE
TABLE OF CONTENTS........................................................ i
INTRODUCTION.......................................................I
1.1 Project Location...................................................1
1.2 Site Characteristics................................................. 1
1.3 Soils............................................................1
1.4 Purpose and Scope of Report .........................................2
1.5 Design Criteria .................................................... 2
1.6 Master Drainage Basin .............................................. 2
2. HISTORIC (EXISTING) DRAINAGE ....................................... 2
3. DEVELOPED FLOWS ................................................... 3
3.1 Method..........................................................3
3.2 Exterior Flows....................................................3
3.3 Onsite Flows.....................................................3
3.4 General Flow Routing .............................................. 3
3.5 Proposed Drainage Plan .............................................4
3.6 Hydrologic Analysis of the Proposed Drainage Conditions ................. 5
3.7 Allowable Street Flow Capacities' ............................... 6
3.8 Inlet Design......................................................6
3.9 Storm Sewer Design...............................................7
4. EROSION CONTROL ................................................... 7
4.1 Erosion and Sediment Control Measures ................................ 7
4.2 Dust Abatement ................................................... 7
4.3 Tracking Mud on City Streets ........................................ 7
4.4 Maintenance......................................................8
4.5 Permanent Stabilization ............................................. 8
4.6 Variances Requested...............................................8
5. FOSSIL CREEK STABILITY STUDY ...................................... 8
6. 500-YEAR FLOODPLAIN FOR FOSSIL CREEK ............................. 9
7. WATER QUALITY......................................................9
8. MISCELLANEOUS....................................................10
8.1 Variances.......................................................10
JREngineering, Ltd.
2620 E. Prospect Rd., Suite 190
Fort Collins, Colorado 80525
(970) 491-9888 • FAX (970) 491-9984
August 19, 1997
Mr. Basil Harridan
City of Fort Collins
Stormwater Utility
235 Mathews Street
Fort Collins, Colorado 80524
Re: Final Drainage and Erosion Control Report
Vencor Fort Collins - Nursing Care Center
Fort Collins, Colorado
Dear Basil:
4935 North 30th Street
Colorado Springs, Colorado 80919
(719) 593-2593 • FAX (719) 528-6613
6110 Greenwood Plaza Blvd.
Englewood, Colorado 80111
(303) 740-9393 • FAX (303) 721-9019
JR Engineering, Ltd. is pleased to submit the attached Final Drainage and Erosion Control Report
for Vencor Fort Collins - Nursing Care Center for your review and approval. The hydraulic and
hydrologic evaluation of the site was performed in accordance with the specifications set forth in the
City of Fort Collins' "Storm Drainage Design and Criteria Manual".
If you have any questions regarding the procedures, methodology, or results presented herein, please
do not hesitate to contact me at your convenience.
Sincerely,
JR Engineering, Ltd.
David W. Klockeman, P.E.
Project Manager
Attachment
D��9
Recycled
FINAL DRAINAGE AND
EROSION CONTROL REPORT
VENCOR FORT COLLINS
NURSING CARE CENTER
Prepared for:
META Associates
401 South Fourth Avenue
Ninth Floor, B&W Tower
Louisville, Kentucky 40202
Prepared by:
JR Engineering, Ltd.
2620 E. Prospect Road, Suite 190
Fort Collins, Colorado 80525
(970)491-9888
August 19, 1997
Job Number 9150.00