HomeMy WebLinkAboutTIMBERLINE VILLAGE - HARMONY SCHOOL SHOPS, 4TH FILING - PDP - 10-03 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTJ
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7. REFERENCES
1. Engineering Professionals, Inc., "Master Drainage Report for Timberline Farm
P.U.D." November 1989.
' 2. Farnsworth Group, "Final Drainage and Erosion Control Study; Harmony School
Shops Third Filing" July 31, 2001.
3. Resource Consultants, Inc., "Fox Meadows Basin (Basin H) Drainage Master
Plan" February 1981.
4. Roberson, Cassidy & Chaudry, Hydraulic Engineering. Boston, MA. 1988.
5. Sear Brown Group, The, "Final Drainage and Erosion Control Study for Harmony
Schools Shops P.U.D. Second Filing" June 1998.
6. "Storm Drainage Design Criteria and Construction Standards (SDDCCS)", May
1984, City of Fort Collins.
7. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated June 2001, and Volume 3 dated September,
1992.
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Timberline Village February 2003
5.3 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 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.
5.4 Maintenance
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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 hay
bale barriers) shall be cleaned when accumulated sediments equal about one-half of trap
storage capacity. Maintenance is the responsibility of the developer.
5.5 Permanent Stabilization
All soils exposed during land disturbing activity (stripping, grading, utility installations,
stockpiling, filling, etc.) shall be kept in a roughened condition by ripping or disking
along land contours until mulch, vegetation or other permanent erosion control is
installed. No soils in areas outside project street rights of way shall remain exposed by
land disturbing activity for more than thirty (30) days before required temporary or
permanent erosion control (e.g. seed/ mulch,landscaping, etc.) is installed, unless
otherwise approved by the Stormwater Utility. Vegetation shall not be considered
established until a ground cover is achieved which is demonstrated to be mature and
stable enough to control soil erosion as specified in paragraph 11.3.10 of the City of Fort
Collins Storm Drainage Construction Standards.
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Timberline Village February 2003
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calculated using methods outlined in the Urban Storm Drainage Criteria Manual. A
drain time of the brim -full capture volume of 40 hours was used. The 100-yr flood will
be detained above the water quality capture volume (WQCV) in Ponds 1. Calculations
for the water quality capture volumes and outlet sizing are included in Appendix F.
' S. EROSION CONTROL
5.1 Erosion and Sediment Control Measures
Erosion and sedimentation will be controlled on -site by use of inlet filters, silt fences,
straw bale barriers, and gravel construction entrances. (See the Drainage and Erosion
Control Plans for details.) These measures are designed to limit the overall sediment
yield increase due to construction as required by the City of Fort Collins. A construction
schedule showing the overall period for construction activities is included in Appendix E
and shown on the Drainage and Erosion Control Plans. Erosion control effectiveness
calculations and cost estimates are also included in Appendix E. The required erosion
control security deposit is $16,147.63. The proposed erosion control plan has. an
effectiveness of 89.8%, which is greater than the required rainfall performance standard
of 79.1 %.
tSilt fences or straw bale dikes will be utilized in limited areas adjacent to any stripping
stockpiles that are created during grading. They will also be used to slow runoff around
the perimeter of the site.
5.2 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.
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sub -basins are included in Appendix B of this report. Since the storm water structures
were designed to convey fully developed flows.
4. STORM WATER FACILITY DESIGN
4.1 Curb Inlets
Curb inlets, curb cuts or sidewalk culverts are proposed where sump conditions exist.
IInlet capacity reduction factors were used to account for inlet clogging. Inlets were sized
using the computer program UDINLET developed by James C. Y. Guo of the University
of Colorado at Denver. Results of UDINLET sizing is equivalent to using Figures 5-2 to
5-6 of the Fort Collins SDDCCS Manual. Computer output files for the inlet sizing are
provided in Appendix C of this report. All inlet locations and sizes are shown on the
Drainage Plan included in the pocket of this report.
' 4.2 Storm Sewer Pipe
Storm sewer pipes are sized to convey the peak 10-year flows calculated using the
Rational Method with peak 100-year overland flow. The computer program StormCAD,
developed by Haestad Methods, Inc., was used for the storm pipe design. StormCAD
considers whether a culvert is under inlet or outlet control and if the flow is uniform,
varied, or pressurized and applies the appropriate equations (Manning's, Kutter's, Hazen -
Williams etc). StormCAD has the capability to utilize the time of concentration and the
runoff coefficient for each basin along with the IDF curves for Fort Collins to determine
the maximum flows that a pipe will experience during a storm event. Therefore, the
flows that are shown on the StormCAD printouts in Appendix D may not match the flows
in the rational method calculations in Appendix B.
A flared end section and riprap is required at all storm sewer outfalls. Riprap is sized
I according to the pipe size and the flow conditions at the outlet. Guidelines from the
"Urban Storm Drainage Criteria Manual" (UDFCD) were used to design the riprap
outfalls. Calculations for storm pipe and riprap sizing can be found in Appendices D and
tE,respectively.
' 4.3 Water Quality
Water quality improvements with extended detention water quality ponds will be
provided for the proposed development. Required water quality capture volumes were
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Sub -basin 113 is that area behind and including building 1. The runoff from this
area is conveyed via overland, gutter flow, and loading dock pipe to a sump inlet
at design point 13.
Sub -basin 114 contains building 9 and the area directly behind it. The runoff
from this basin is conveyed to the regional detention pond north of building 9 via
roof drains and sheet flow.
Sub -basin 115 is the portion of Harmony Road east of the site entrance and the
berms that drain to Harmony Road. These flows are conveyed to a curb cut at the
southeast corner of the site. From here, runoff flows to the low point in sub -basin
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112.
Runoff from sub -basin OS-1 is conveyed via overland and sheet flow to
Milestone Drive where a sump inlet intercepts the flows and conveys them into
the regional detention pond.
Runoff from sub -basin OS-2 is conveyed via overland and gutter flow to a sump
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inlet at design point 3. These flows are piped to the regional detention pond.
Runoff from sub -basin OS-3 is conveyed via roof drains, overland flow, and
gutter flow to sub -basins 101 and 102 to be conveyed to the sump inlet at design
point 3.
Runoff from sub -basin OS-4 is conveyed via sheet flow and gutter flow to sub -
basin 106.
Runoff from sub -basin OS-5 is conveyed via the north gutter of Harmony Road
to the south entrance of the site and sub -basin 106. From here it is routed to
design point 7 and then to the regional detention pond.
3.3 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 as specified in the "City of Fort Collins Storm Drainage Design
Criteria and Construction Standards". All hydrologic calculations associated with the
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Timberline Village February 2003
Sub -basin 101 contains the area around the future building area number 6. The
runoff generated from this area is conveyed to the area inlet at design point 3 via
overland and gutter flow. From the inlet at design point 3, flows are routed to the
regional detention pond to the north.
Sub -basin 102 includes the parking area and drive area south of Building 7 and
east of building 6. Runoff from this basin is conveyed to the area inlet at design
point 3. These flows are routed to the regional detention pond to the north.
Runoff from sub -basin 103 is conveyed via sheet and gutter flow to the area inlet
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at design point 3. These flows are routed to the regional detention pond.
Runoff from sub -basin 104 sheet flows to Milestone Drive and then is routed to
Sub -basin 105 includes the area between buildings 8 and 9. The runoff from this
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area is conveyed to one of two sump inlets via sheet and gutter flow. This runoff
is then routed to the regional detention pond to the northeast.
' Sub -basin 106 includes that area around building 5. This basin's runoff is
conveyed via overland flow and gutter flow to sub -basin 107. The flows from
sub -basin 107 are joined by those from sub -basin 106 and are conveyed to a
' sump inlet in the parking lot at design point 7.
' Sub -basins 108 and 109 are those areas that lie in the front of buildings 7,8, and
9. The runoff from these areas is conveyed to the sump inlet at design point 9.
These flows are then piped to the regional detention pond to the north.
Sub -basin 110 includes the parking area in front of building 1. The flows from
this area are conveyed via overland and gutter flow to a sump inlet at design point
' 10 to be delivered to the regional detention pond.
Sub -basin 111 includes the area between buildings 1 and 9. The runoff from
this area is conveyed to the area inlet at design point 11 to be piped to the regional
detention pond.
Sub -basin 112 includes the area east of the entrance and south of building 1. The
runoff from this area is conveyed via overland and gutter flow to the sump inlet at
design point 12. These flows are piped to the north to the regional detention
pond.
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Local drainage facilities, including storm pipes and inlets, were designed to carry peak
100-year flows calculated using the Rational Method. The regional detention facility was
evaluated under the 100-year storm event using MODSWMM.
' 1.5 Vertical Datum
' Two benchmarks were used as a basis for all elevations, these benchmarks being the City
of Fort Collins vertical control benchmark #10-94 and benchmark #12-94. Benchmark
' #10-94 lays in the southeast corner of Timberline Road and Harmony Road on the north
end of the west concrete headwall over the irrigation ditch. This benchmark elevation is
4966.81. Benchmark #12-94 lays on the south side of east Harmony Road, 300 feet west
' of Corbett Drive on the top of a concrete wall of an irrigation drop structure. This
benchmark elevation is 4950.01.
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2. HISTORIC DRAINAGE
The Timberline Village project site includes approximately 15.9 acres of land. The
majority of the site is currently covered in native grasses. Generally, the site drains in a
northeasterly direction. Slopes vary from 0.5 to 5% on site.
Soils on site are predominately Nunn Clay Loams (Soil number 74). These soils are
characteristically known to have slow to medium runoff, wind erosion is slight and water
erosion is moderate. These soils belong to the Hydrologic group C.
3. LOCAL HYDRAULIC ANALYSIS FOR DEVELOPED CONDITIONS
3.1 General Flow Routing
The concept for the overall site drainage follows that outlined in the Conceptual Drainage
Analysis dated March 14, 2002. This report routed flows to the regional detention pond
in the northeast portion of the site for detention and water quality.
3.2 Proposed Sub -basin Descriptions
A summary of the drainage patterns within each sub -basin and at each design point is
provided in the following discussion. Details of the drainage facility design are included
in Section 4.
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Timberline Village February 2003
' 1. INTRODUCTION
1.1 Project Description
' Timberline Village is a proposed commercial development located in a portion of the
southwest quarter of Section 32, Township 7 North, Range 68 West of the Sixth Principal
' Meridian, in the City of Ft. Collins, Larimer County, Colorado. The site is bounded by
Timberline Road to the west and Harmony Road to the South. Sunstone Village 7th
' Subdivision is to the north and the Poudre Valley Hospital South Campus is to the south
of the site. A vicinity map is included in Appendix A.
' 1.2 Master Drainage Basin & Other Drainage Reports
The Master Drainage Basin for Timberline Village is the Fox Meadows Basin. The "Fox
Meadows Basin Drainage Master Plan" by Resource Consultants, Inc. dated February
1981 and the "Master Drainage Report for Timberline Farm P.U.D." by Engineering
' Professionals, Inc. dated November 1989 were both consulted during preparation of this
report.
1 1.3 Purpose and Scope of Report
This report describes the proposed drainage facilities for Timberline Village and includes
consideration of all on -site and tributary off -site runoff. Design calculations are included
' for all drainage structures including temporary detention facilities required for this Project
Development Plan.
r1.4 Design Criteria & Methods
I This report and associated calculations were prepared to meet requirements established in
the "City of Fort Collins Storm Drainage Design Criteria and Construction Standards"
(SDDCCS), dated May 1984 and updated January 1997. The new rainfall criteria as
' amended by Ordinance 42.199 was used for the 2, 10 and 100 year design storms. The
stormwater drainage design for Timberline Village also takes into account guidelines set
forth in the Timberline Farms P.U.D. Master Plan. Where applicable, the criteria
established in the "Urban Storm Drainage Criteria Manual" (UDFCD), developed by the
' Denver Regional Council of Governments, were also used.
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Timberline Village February 2003
TABLE OF CONTENTS
PAGE
TABLEOF CONTENTS...............................................................................................................
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1.
INTRODUCTION................................................................................................................I
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1.1 Project Description.....................................................................................................
1
1.2 Master Drainage Basin & Other Drainage Reports ....................................................
1
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1.3 Purpose and Scope of Report .....................................................................................
1.4 Design Criteria & Methods........................................................................................
1
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1.5 Vertical Datum...........................................................................................................
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2.
HISTORIC DRAINAGE..........................................................................................................
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3.
LOCAL HYDRAULIC ANALYSIS FOR DEVELOPED CONDITIONS .........................
3.1 General Flow Routing................................................................................................
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3.2 Proposed Sub -basin Descriptions...............................................................................
2
3.3 Hydrologic Analysis of the Proposed Drainage Conditions ......................................
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4.
STORM WATER FACILITY DESIGN..............................................................................
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4.1 Curb Inlets..................................................................................................................
4.2 Storm Sewer Pipe.......................................................................................................
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4.3 Water Quality.............................................................................................................
5
5.
EROSION CONTROL.........................................................................................................
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5.1 Erosion and Sediment Control Measures...................................................................
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5.2 Dust Abatement..........................................................................................................
6
5.3 Tracking Mud on City Streets....................................................................................
7
5.4 Maintenance...............................................................................................................7
5.5 Permanent Stabilization.............................................................................................
7
7.
REFERENCES.....................................................................................................................8
APPENDIX A MAPS AND FIGURES
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APPENDIX B HYDROLOGIC CALCULATIONS
APPENDIX C INLET CALCULATIONS
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APPENDIX D STORM PIPE CALCULATIONS
APPENDIX E EROSION CONTROL CALCULATIONS
APPENDIX F WATER QUALITY CALCULATIONS
APPENDIX G DETENTION POND DESIGN
APPENDIX H EXCERPTS FROM OTHER REPORTS
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Final Drainage and Erosion Control Report
Timberline Village
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February 2003
February 25, 2003
Mr. Basil Hamdan
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: Drainage and Erosion Control Report for Timberline Village
Dear Basil,
J•R ENGINEERING
A Subsidiary of Westrian
We are pleased to submit to you for your approval, this Drainage and Erosion Control Report
for Timberline Village. All computations within this report have been completed in compliance
with the City of Fort Collins Storm Drainage Design Criteria dated May 1984, revised January
1997.
We greatly appreciate your time and consideration in reviewing this submittal. Please call if
you have any questions.
Sincerely,
JR Engineering
Prepared by,
Amber Kauffman, E.I.
Design Engineer H
attachments
Reviewed by,
Alvin C. Duncan, P.E.
Senior Project Engineer
2620 Fan Prospect Road, Suite 190, Fort Collins, CO 80525
970-491-9888 • Fax. 970-491-9984 • w gxengineering.wrn
DRAINAGE AND EROSION CONTROL
REPORT FOR
TIMBERLINE VILLAGE
Prepared by
JR ENGINEERING
2620 E. Prospect Rd., Suite 190
Fort Collins, Colorado 80525
(970)491-9888
Prepared for
Miller Weingarten Realty, LLC
2 Inverness Drive East, Suite 200
Englewood, CO 80112
February 25, 2003
Job Number 39347.00