HomeMy WebLinkAboutTRAILHEAD - PDP - 43-02A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTalong the north side of East Vine Drive into a natural grass swale that flows into a sump inlet
which discharges into a detention pond on the Waterglen, P.U.D. The Rational Method
determined the 2-yr and 100-yr historic flows to be 3.66 cfs and 10.3 cfs, respectively.
Basin H-15 consists of 47.9 acres and is located in the northeastern portion of the site. This
basin corresponds to master drainage basin 15. However, flows in this basin first drain
southwest at slopes ranging from 0.2 to 1.9 percent to the Larimer and Weld Canal, where
they then drain east and north to design point 15 located in the upper northeast corner of the
basin. The Rational Method determined the 2-yr and 100-yr flows for this basin to be 4.34
cfs and 12.14 cfs, respectively.
The Waterglen P.U.D. combined these two basins as offsite basin OS-2 and sized the
detention pond in the Waterglen P.U.D. to include the flow from this combined basin as
offsite flows of 7.41 cfs. Therefore, when releasing from our pond to the Waterglen P.U.D.,
we will maintain a release rate of 7.41cfs.
Basin H-16, located in the southwestern portion of the site, consists of 27.4 acres and
corresponds with basin 16 in the master drainage plan. Flows from this basin travel
southwest at slopes of 0.3 to 2.9 percent to an old wooden culvert and RCP. These flows
travel under East Vine Drive and the railroad tracks to historic master basin 10. The Rational
Method determined the 2-yr and 100-yr flows for this basin to be 4.70 cfs and 13.21 cfs,
respectively.
3. LOCAL DEVELOPED DRAINAGE DESIGN
3.1 Method
The Rational Method was used to determine the 2-year and 100-year flows for the sub -basins
indicated in this drainage report. Drainage facilities were designed to convey the 100-year
peak flows. In most instances the flows were routed according to their time of concentration
so that the calculations in Appendix E will not just be adding maximum flows to each inlet.
They will be shown as the peak flow through that pipe with the routed flows. The hydrologic
calculations are found in Appendix B of this report.
Drainage and Erosion Control Report . Page 3
Trail Head Property November 25, 2003
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LEGEND
DRAINAGE BASIN BOUNDARY
MAJOR EXISTING CONTOUR
MINOR EXISTING CONTOUR
PROPERTY BOUNDARY
— — — — — OVERLAND FLOW
CHANNELIZED FLOW
Q= 2-YR HISTORIC STORM
FLOW DIRECTION
400 200 0 400 800
101 BASIN IDENTIFICATION
1.0 .80 RUNOFF COEFFICIENT
AREA IN ACRES
10 DESIGN POINT
HISTORIC BASINS
TRAIL HEAD PROPERTY
JOB NO. 39145.11
OCTOBER 03, 2003
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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 and revised in January 1997. Where applicable, the criteria established in
the "Urban Storm Drainage Criteria Manual" (UDFCD) dated 1984, developed by the
Denver Regional Council of Governments has been utilized. The rainfall criteria used was
the April 1999 amended criteria.
1.5 Master Drainage Basin
Trail Head Property lies in the Boxelder Creek/Cooper Slough Basin. The master study for
this area is the "Technical Documentation for the Hydrologic Modeling of the Boxelder
Creek/Cooper Slough Basin, Volume r' by Anderson Consulting Engineers, Inc., 2002,
henceforth referred to as the master drainage plan in this report. Another applicable report is
the "Final Drainage and Erosion Control Report Waterglen, P.U.D." by JR Engineering,
dated August 11, 1997. Trail Head Property is located in the master plan basin number 15,
and in portions of 14 and 16. The existing drainage patterns for this site, as identified in the
master drainage plan, are incorrect (refer to Figure B.2 in Appendix A). Two discrepancies
were noted. Basin 16 does not drain southwest to Basin 11 but drains south to Basin 10.
Basin 15 drains north via the Latimer and Weld Canal to Basin 14. Therefore, in order to
determine the correct 2-yr historic storm event, the historic flows for this site were
reanalyzed in this report.
2. HISTORIC (EXISTING) DRAINAGE
For this analysis, based on existing topography, the Trail Head Property was divided into
three historic drainage basins, H-14, H-15 and H-16 (refer to Figure 1). The Rational
Method was then used to determine the 2-year and 100-year historic flows for each basin.
Basin H-14 consists of 17.5 acres and is located in the southeast portion of the site. This
basin corresponds with the southwestern portion of master drainage basin 14. Flows in this
basin consist of on -site flows via overland flow in a southeasterly direction to design point 14
located in the southeastern corner of the basin at slopes that range from 0.5 to 5.8 percent.
Once these flows leave the Trail Head Property, they are conveyed easterly via gutter flow
Drainage and Erosion Control Report Page 2
Trail Head Property November 25, 2003
1. INTRODUCTION
1.1 Project Description
Trail Head Property is located in the Southeast One -Quarter and the Northeast One -Quarter
of Section 4, Township 7 North, Range 68 West of the Sixth Principal Meridian, in the -City
of Fort Collins, Larimer County, Colorado. The Trail Head Property is bounded on the south
by East Vine Drive, on the east by Waterglen, P.U.D. and on the northwest by the Colorado
and Southern (C & S) Railroad. A location map is provided in Appendix A.
1.2 Existing Site Characteristics
The project site includes approximately 88.8 acres of land. The majority of the Trail Head
Property is covered with native grasses. The southwest side of the property is currently being
farmed with alfalfa.
The soils in the area are reported in the Soil Survey of Larimer County Area, Colorado and
are identified as being predominately Fort Collins Loams (soil number 35), Nunn Clay
Loams (soil number 73) and Santana Loams (soil number 95). These soils belong to the
hydrologic group C and are known to have slight to moderate erosive characteristics and
slow to moderate runoff characteristics. Please refer to Appendix A for specifics on each
soil.
East Vine Drive is an existing two-lane road and is anticipated to be improved to a four -lane
arterial street in the near future. JR Engineering is currently designing an ultimate layout for
the portion of East Vine Drive directly south of the site from Elgin Court to about 1000 feet
west of the Trail Head Property boundary. This ultimate design is considered in the design of
Trail Head Property.
1.3 Purpose and Scope of Report
This report defines the proposed drainage and erosion control plan for Trail Head Property.
The plan includes consideration of all on -site and if applicable, tributary off -site runoff. The
plan addresses the hydrologic ramifications associated with the development of the Trail
Head Property and identifies the proposed storm facilities that will allow this project to
develop without impacting downstream properties. _
Drainage and Erosion Control Report Page t
Trail Head Property November 25, 2003
TABLE OF CONTENTS
PAGE
TRANSMITTAL LETTER.................................................................................. i
TABLE OF CONTENTS.............................................................................................................. ii
1. INTRODUCTION..................................................................................................................1
1.1 Project Description......................................................................................................... 1
1.2 Existing Site Characteristics........................................................................................... 1
1.3 Purpose and Scope of Report ......................................................................................... 1
1.4 Design Criteria................................................................................................................ 2
1.5 Master Drainage Basin................................................................................................... 2
2. HISTORIC (EXISTING) DRAINAGE................................................................................ 2
3. LOCAL DEVELOPED DRAINAGE DESIGN (To be submitted with First Final) .......3
3.1
Method............................................................................................................................3
3.2
General Flow Routing....................................................................................................
4
3.3
Proposed Drainage Plan.................................................................................................
4
3.4
Hydrologic Analysis of the Proposed Drainage Conditions ...........................................
8
4. HYDRAULIC ANALYSIS (To be submitted with First Final) .........................................
9
4.1
Allowable Street Capacity..............................................................................................
9
4.2
Inlet Sizing......................................................................................................................
9
4.3
Storm Sewer System.......................................................................................................
9
4.4
Pond Description..........................................................................................................10
5. MODSWMM AND EXTRAN (To be submitted with First Final)..................................11
6. EROSION CONTROL (To be submitted with First Final).............................................13
6.1 Erosion and Sediment Control Measures..................................................................... 13
6.2 Dust Abatement............................................................................................................13
6.3 Tracking Mud on City Streets...................................................................................... 13
6.4 Maintenance................................................................................................................. 14
6.5 Permanent Stabilization................................................................................................ 14
7. REFERENCES.....................................................................................................................15
Appendix A: Maps and Figures
Appendix B: Hydrologic Calculations
Appendix C: Street Capacity Calculations (To be submitted with First Final)
Appendix D: Inlet Calculations (To be submitted with First Final)
Appendix E: Storm Pipe and Swale Calculations (To be submitted with First Final)
Appendix F: Pond Sizing Calculations Including ModSwmm (To be submitted with First Final)
Appendix G: Erosion Control (To be submitted with First Final)
Appendix H: Reference Reports
DRAINAGE AND
EROSION CONTROL REPORT
Trail Head Property
Prepared for:
Hartshorn Properties, LLC
Mr. Ken Crumb, Manager
P.O. Box 337600
Greeley, Colorado 80633
(970)304-1392
Prepared by:
JR Engineering
2620 E. Prospect Road, Suite 190
Fort Collins, Colorado 80525
(970)491-9888
December 23, 2003
A SL':
o•
sr 37953
Timothy J. Halopoff, P.E. Exp. 10/31/2005
Job Number 39145.11
J•R ENGINEERING
A Westrian Company
December 23, 2003
Mr. Basil Hamdan
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: Trail Head Drainage and Erosion Control Report
Dear Mr. Hamdan:
We are pleased to submit to you for your review and approval this preliminary Drainage and Erosion
Control Report for Trail Head Property. All computations within this report have been completed in
compliance with the City of Fort Collins Storm Drainage Design Criteria. Since this submittal has
been deemed a preliminary submittal at 50% completion, JR Engineering has provided existing
condition rational hydrology calculations, preliminary developed condition hydrology calculations,
preliminary detention facility sizing calculations and anticipated plan view storm drain sizing on the
overall utility layout. Once the general drainage patterns and storm drain locations have been
preliminarily reviewed and accepted, we plan to fully analyze all hydrology, hydraulic and erosion
control aspects of drainage on this site. These analyses will be provided in this report with future
submittals.
We greatly appreciate your time and consideration in reviewing this preliminary submittal. Please,
feel free to contact me with any questions or comments that you may have.
Sincerely,
Timothy J. Halopoff, P.E.
Project Engineer
2620 Fast Prospect Road, Suite 190, Fort Collins, CO 80525
970-491-9888 • Fax: 970-491-9984 • w ..jrengineering.com